1

The Management of Invasive Species in Marine & Coastal Environments

Module 1

Introduction to Marine and Coastal Invasive Species

2

TABLE OF CONTENTS

1. INTRODUCTION TO MARINE AND COASTAL INVASIVE SPECIES Objectives of the Module 3 1.1 What is an Invasive Alien Species? 3 1.1.1 Invasive and alien? 4 1.1.2 Related Terminology 5 1.1.3 What Types of Species Invade? 6 1.1.4 The Process of Invasion 7 1.1.5 Defining Pathways 8 1.2 IAS introductions in marine and coastal environments 11 1.2.1 Intentional introductions 12 1.2.1.1 Mariculture Industry 13 1.2.1.2 Aquaria Releases 16 1.2.1.3 Coastal Management/ Restoration 17 1.2.2 Unintentional Introductions 18 1.2.2.1 Ballast Water 19 1.2.2.2 Biofouling / Hull Fouling 22 1.2.2.3 Drifting Marine Debris 25 1.2.2.4 Canals, Seaways and Internal Waterways 26 1.2.2.5 Range Expansions in a Changing World 27 1.3 Impacts 28 1.3.1 Ecological Impacts 28 1.3.2 Economic Impacts 29 1.3.3 Public Health Impacts 32 1.4 Predicting Invasions 34 1.4.1 Species Characteristics 34 1.4.2 Environmental Conditions & Disturbance 35 1.4.3 Other Factors 36 1.4.4 Current Practice 36 1.5 The Need for IAS Management 37

3

Objectives of this module: • Define invasive species and related terminology • Describe the invasion process • Outline intentional and unintentional introductions • List the primary pathways of invasive marine & coastal species introduction • Describe the types of impacts associated with invasive marine species • List some of the characteristics of invasive marine species • Explain the impact of globalisation on the invasive marine species problem • Present case studies of marine and coastal invasive alien species

INTRODUCTION TO THE MANAGEMENT OF MARINE AND COASTAL INVASIVE SPECIES1

The spread of invasive alien species is one of the major threats to the ecological and economic well being of the planet (GISP)

1.1 What is an Invasive Alien Species? Invasive alien species are now generally recognised as one of the greatest threats to biodiversity globally. They also have serious economic, environmental and health impacts and, as a result, place major constraints on development. In marine and coastal environments, invasive species have been identified as one of the four greatest threats to the world’s oceans along with:

• Land-based sources of marine pollution • Over-exploitation of living marine resources • Physical alteration/destruction of marine habitats

However, the understanding and management of marine and coastal invasions is an immature, emerging science and its terminology continues to evolve and change. As a result, there is currently no widely accepted, comprehensive glossary of terms on the subject. Instead, there is widespread use of apparently interchangeable but often ambiguous and confusing terms, which can hinder understanding and progress.

4

The following definitions attempt to give clarity and context to some basic terms, while highlighting sources of ambiguity or overlap with synonymous or similar terms. Other important terms may be defined in subsequent sections and modules as appropriate. A comprehensive list of terms and definitions associated with marine invasive species can be found in Annex I to the Course Modules. 1.1.1 Invasive and alien? An Invasive Species is one which has established and spread – or has the potential to do so – outside of its natural distribution range, and which then threatens ecosystems, habitats and/or other species, potentially causing economic and/or environmental damage, or harm to human health. The majority of invasive species are alien, but it is important to note that native species may also become invasive, usually under altered environmental conditions. However, to date, these types of invasions – as far as is known – have been more common in terrestrial environments than in the marine realm. Alien species – a species that has been intentionally or unintentionally introduced to a location, area, or region where it does not occur naturally. According to the Convention on Biological Diversity (CBD) “Alien species” refers to a ‘species, subspecies or lower taxon, introduced outside its natural past or present distribution; including any part, gametes, seeds, eggs, or propagules of such species that might survive and subsequently reproduce’. Synonymous terms such as non-native species or non-indigenous species are more precise and may be used for increased clarity to replace such terms as introduced, exotic, feral, foreign, ornamental or weedy species. Invasive alien species (IAS) – an alien species that causes, or has the potential to cause, harm to the environment, economies, or human health. Because the majority of invasive species are alien, this term is widely used by practitioners in the field. There are various versions of the IAS definition. For example, the Convention on Biological Diversity (CBD) defines an IAS as an alien species whose establishment and spread threatens ecosystems, habitats or species with economic or environmental harm. An invasive alien species according to the IUCN - the World Conservation Union - is an alien species, which becomes established in natural or semi-natural ecosystems or habitat, is an agent of change, and threatens native biological diversity. The important point is that it is the invasiveness of a species which causes the problem. Alien species that do not become invasive may not be a serious threat, though they should be monitored in case they do start to spread.

5

Marine invasives are called by a variety of names including Introduced Marine Pests (IMPs) (Australia and New Zealand), Aquatic Nuisance Species (ANS) (United States), Harmful Marine Species (IMO Ballast Water Convention). Box1.1 Definitions in national laws Under South Africa’s National Environmental Management: Biodiversity Act (2004) an ‘‘alien species’’ is defined as: (a) a species that is not an indigenous species; or (b) an indigenous species translocated or intended to be translocated to a place outside its natural distribution range in nature, but not an indigenous species that has extended its natural distribution range by natural means of migration or dispersal without human intervention; while an ‘‘invasive species’’ is any species whose establishment and spread outside of its natural distribution range: (a) threatens ecosystems, habitats or other species or has demonstrable potential to threaten ecosystems, habitats or other species; and (b) may result in economic or environmental harm or harm to human health. The official US definition of an invasive species was provided in Executive Order 13112 signed by President Bill Clinton on February 3, 1999. It defines an invasive species as an alien species whose introduction does, or is likely to, cause economic or environmental harm or harm to human health. 1.1.2 Related Terminology Introduction - The movement by human action of a species from one area to another outside its native range. This movement can be either within or between countries. According to the CBD definition, ‘An introduction/translocation is the human-assisted movement of an organism to an area outside its natural range’ and ‘An introduced marine species is a marine species that’s movement has been assisted by human activities to an area outside its range’. To quote US Aquatic Nuisance Species (ANS) Executive Order 13112 (Clinton 1999): ‘"Introduction" means the intentional or unintentional escape, release, dissemination, or placement of a species into an ecosystem as a result of human activity’.

6

Cryptogenic species - A ‘cryptogenic species’ is simply “neither demonstratively native nor introduced" (Cohen & Carlton 1995, Carlton 1996). Many of the widespread and so-called ‘cosmopolitan’ marine species are cryptogenic because their original, natural distribution has been blurred by centuries of transfers via sailing ships, canals, barges, aquaculture, etc. In fact in some regions many historical introductions had been assumed part of the native marine community until recent studies invoked doubt. Examples include several common foulers and wood-borers, such as the infamous bivalve ‘shipworm’ (Teredo navalis), the ship or striped barnacle (Balanus amphitrite), both blue (Mytilus) and brown (Perna) mussel complexes and some oyster species. This term is of particular relevance to marine systems, as historical biogeographic records may not be available for many species. In the case of suspected but unproven harmful invasive species, terms such as ‘suspected harmful IAS’, ‘risk species’ or ‘potential marine pest’ may be used, especially when trying to identify potential ‘next pests’. Such terms are useful whenever feared or predicted impacts are not yet confirmed through observation or evidence. 1.1.3 What Types of Species Invade? In the marine realm, as well as on land, there are examples of invasive species from all different taxonomic groups, ranging from plants, to vertebrates and even microbes. Examples of most taxa can be found in the case studies which are described at other points in the modules. Although a wide variety of species have the potential to become invasive, those that are commonly associated with the major vectors are more likely to be introduced to new geographic regions. For example, organisms that attach themselves to hard surfaces, such as barnacles and tube worms, are commonly seen attached to the hulls of vessels, or other structures. These are often referred to as fouling organisms, or biofouling. Organisms that are introduced for specific purposes, such as fishing or mariculture may themselves become invasive. They may also carry parasites or bacterial and viral infections. Invasions of disease organisms introduced in this way have had serious impacts on local seafood industries. Almost any type of organism can be transferred in situations where water is transported from one ecosystem to another (e.g. ballast water in ships). This is because almost all marine species – including many fish - have a planktonic stage in their life cycle (see figure 1.6), and these free-floating larval forms are easily transported in a viable state.

7

1.1.4 The Process of Invasion There are three main phases in the invasion process as follows:

1. Introduction of the species Species must survive during and after the journey. Many species fail to survive unless they are cared for (e.g. intentional imports) because of unsuitable environmental conditions such as light, temperature, salinity, nutrient levels, etc.

1. Introduction

3. Spread The established species begins to multiply and spread, sometimes after a substantial time lag (or lag phase) i.e. of a few years, or even decades. This is the explosion phase (i.e. they become invasive).

2. Establishment and reproduction of tintroduced species

he

The survivors must persist and reproduce successfully until they naturalise i.e. establish a self-sustaining ‘founder population.’

2. Establishment

3. Spread

The founder population is the initial group of organisms of the same species that establishes in the new environment. A minimum number of individuals, referred to as a minimum viable population, is usually necessary for such a population to expand successfully. The size of a minimum viable population will vary depending on the species and also on environmental conditions. Observations have shown that all invasive species, including marine species, tend to have a lag phase during which they are low in abundance and their impacts are not noticeable. However, over time the population increases rapidly (explosion phase) and the impacts become apparent. The lag phase is unpredictable in duration. Following the explosion phase, the population levels out as it reaches the carrying capacity of the environment (Figure 1.1).

8

Time

Popu

latio

n si

ze

Lag phase

Carrying capacity

Figure 1.1 Invasion process

Explosion phase

Although a time lag is a general feature of the invasion process, there are some organisms, which have virtually no time lag at all and the effects of their invasiveness can be seen almost immediately (e.g. some parasites, diseases, algal blooms). It is also important to note that many introduced alien species will not experience a population explosion, and will therefore not become invasive. 1.1.5 Defining Pathways and Vectors Species introductions may be intentional or unintentional, and occur through a variety of pathways. Table 1.1 lists examples of known pathways for marine and coastal invasives, but there may be others that have not yet been identified. Knowledge and understanding of invasion pathways will enable countries to take appropriate action to prevent them from delivering harmful species to their doorsteps. A pathway is broadly defined as the means (e.g. aircraft, vessel or person), purpose or activity (e.g. mariculture, shipping or aquarium trade), or a commodity (e.g. fisheries) by which an alien species may be transported to a new location, either intentionally or unintentionally. The more specific mechanism for species transfer, within each pathway is referred to as a vector. An example demonstrating this distinction is that within the shipping pathway, ballast water, biofouling and cargo each act as independent vectors, with different approaches to management. Pathways can also be divided into primary and secondary categories (Figure 1.2). Primary pathways refer to those vectors and routes which move species to new regions or provinces across major oceanic, landmass or climatic barriers (i.e. trans-oceanic and intercontinental pathways), while secondary pathways help spread and disperse invasive marine species between points within or between neighboring regions (e.g. the routes used by domestic and local ‘hub’ shipping, fishing vessels or trailered boats).

9

‘Secondary’ pathways include all ‘within-region’ activities and circumstances, which can facilitate the local spread of an invasive marine species after its founder population has established. These secondary range expansions may start quickly or require several years or even decades before eventual removal of some internal or external constraining factor/s provides the impetus (e.g. genetic acclimation, an improved waterway, new trading route, removal of a weir or barrage or favourable shift in temperature/salinity regime, etc). Note that species can also expand their range through natural means. For example, species can swim or drift on currents to new locations. Some species or fragments of them can be moved to new locations by wind, currents and in or on animals. This is referred to as natural dispersal and not an introduction. Natural dispersal may play a significant role in the secondary spreading of an alien species once introduced to a new region or country.

Figure 1.2 Primary and secondary pathways.

10

Ships Planktonic and nektonic organisms in ballast water Attached and free-living fouling organisms on hull, on rudder, on propeller and propeller shaft, in sea-water systems, seachests, in ballast tanks, and in ballasted cargo holds Organisms associated with anchors, anchor chains, and anchor chain lockers Organisms associated with cargo, such as logs that have been floated for loading

Drilling Platforms Attached and free-living fouling organisms Planktonic and nektonic organisms in ballast water

Dry Docks Attached and free-living fouling organisms Planktonic and nektonic organisms in ballast water

Navigation Buoys and Marina Floats Attached and free-living fouling organisms

Amphibious Planes, Seaplanes Attached and free-living fouling organisms Organisms in pontoon water

Canals Movement of species through sea level, lock, or irrigation canals

Public Aquaria Accident or intentional release of organisms on display Accidental or intentional release of organisms accidentally transported with target display species

Research Movement and release of invertebrates, fish, sea-weeds (algae) and seagrasses used in research (intentional or accidental escape) Organisms associated with research and sampling equipment, including SCUBA and other diving or swimming gear

Floating Marine Debris Transport of species on human-generated debris, such as floating nets and plastic detritus

Recreational Equipment Movement of small recreational craft, snorkelling and SCUBA gear, fins, wetsuits, jet skis, and similar materials

Fisheries, including Marine Aquaculture (Mariculture) Transplantation or holding of shellfish, such as oysters, mussels, clams, crabs, lobster, and other organisms; fish; or seaweed (algae) in the open sea for growth or freshening (rejuvenation); and other organisms associated with dunnage and containers Intentional release of shellfish, fish, and seaweed (algae) species, either as part of an official governmental introduction attempt, or as an illegal private release Stock enhancement, often ongoing, as well as accidentally transported associated organisms Movement of live seafood intended for sale but then released into the wild Processing of fresh or frozen seafood and subsequent discharge of waste materials to environment, which may include associated living or encysted organisms Movement of live bait subsequently released into the wild Discarding of packing materials - such as seaweed and associated organisms - used with live bait and seafood Movement, relocation, or drifting of fisheries gear, such as nets, floats, traps, trawls, and dredges Release of organisms as forage food for other species Organisms transported intentionally or accidentally in "live well" water, vessel scuppers, or other deck basins Release of transgenic stocks - genetically modified organisms (GMOs) Movement of algae and associated organisms as substrate for fish egg deposition

Aquarium Pet Industry Movement and release of invertebrates, fish, seaweeds (algae) and seagrasses used in the aquarium industry (intentional or accidental escape)

Restoration Movement of marsh, dune, or seagrasses as well as associated organisms Reestablishment of locally extinct or decimated populations of native species, and accidentally transported associated organisms

Education Release of species from schools, colleges, and universities following classroom use

Table 1.1 Pathways of aquatic invasion (extracted from Carlton, 2001).

11

1.2 IAS introductions in marine and coastal environments Over past millennia, aquatic species have dispersed freely throughout the world’s oceans by natural means such as ocean currents, climatic conditions, ocean surface winds, attached to floating logs, etc. The only barriers to their spread have been natural biological and environmental factors such as temperature, salinity, landmasses and natural predators. Nowadays, however, human activities enable species to cross these barriers. Many marine and coastal species have therefore been able to establish new populations outside of their native range and potentially threaten native species and/or cause major ecological and environmental damage, pose a threat to humans and in many cases, have a serious effect on the economy. These incursions have shown a dramatic increase in frequency, extent and damage over the last half a century or so and there is every indication of this trend continuing. There is little doubt that this is due largely to the increased reliance upon shipping and fisheries in the world market. Arguments that all marine species capable of introduction have now established in all possible areas (because vectors such as hull fouling, solid ballast, water ballast and aquaculture have not been managed until recently) have been widely rejected. There are many cases where species must have been translocated for many decades but did not establish until recent times, and these have been related to the concept of increased ‘propagule pressure’ (see Section 1.5). Propagule pressure increases whenever improvements to the pathway cause the founding population to be larger, fitter and/or introduced more frequently. Other factors explaining the rise in marine introduction and spread rates since the 1960s are the anthropogenic changes that have made many aquatic receiving environments more ‘invader friendly’. As described in Section 1.6.2, these changes include increased amounts of disturbed, artificial and/or eutrophic habitats, plus cases where either diversion of freshwater discharges to public supply/irrigation schemes, river water ionisation from industrial outfalls and urban run-off and/or regional climate change, have reduced the incidence of low salinity and temperature extremes. Local selection pressures operating on IAS founder populations may also help their offspring retain or gain more pre-adaptations facilitating better chances of further translocation than their native counterparts. The deliberate introduction of species beyond their natural range is closely linked to the historical and present day movement of humans across the globe. Wherever humans have travelled, they have introduced species to new locations for food, social or economic purposes. This type of introduction is referred to as an intentional introduction. Many more species have been accidentally transported around the world as the consequence of human activities such as trade, travel and transport. These are called unintentional introductions (Figure 1.3).

12

Marine Alien Species Introductions

Unintentional

Intentional

Authorised/ Legal

Unauthorised Non-Shipping Shipping Related

Directly released into wild Ballast water Associated with fisheries/mariculture

Associated with Aquariums (private, public, research)

Released into captivity Biofouling

Escaped or intentionally released

Figure 1.3 Types of alien species introductions

1.2.1 Intentional introductions Intentional introductions may be authorised as part of a legal process, or unauthorised and therefore illegal. Authorised introductions include the following:

• Deliberate introduction of various species of macroalgae, molluscs, crustaceans and fish for restocking and/or mariculture for recreational and commercial purposes;

• The importation of various macroalgae, molluscs, crustaceans and fish for use in domestic, public or research aquaria or facilities;

• The deliberate introduction of coastal species for coastal management or restoration purposes e.g. dune stabilisation, re-introduction of locally extinct or depleted populations.

The majority of these authorised introductions are intended to be introductions into captivity, whether to cages or onshore facilities (for mariculture species), or to aquaria or other facilities. However, these species may subsequently be either intentionally or accidentally released (these constituting unauthorised introductions to the wild). Moreover, all introduced species may carry pathogens, or parasites with them – these being unintentional introductions. These facts need to be taken into consideration when permits for intentional introductions are issued.

13

Box 1.2 Historical context of intentional introductions Historically, most intentional releases into the wild comprised various attempts by individuals from Europe or North America settling in new parts of the world to establish wild stocks of various prized shellfish and finfish species. The objectives of such attempts were to énrich’ local stocks for sentimental, commercial and/or recreational purposes. For example, deliberate introductions of commercial and recreational European marine species were attempted in Australia, New Zealand, North America and South America following their European colonisation. Similarly, there were deliberate introductions into the Hawaiian Islands in the 1950s-1960s.These introductions included a wide range of biota including seaweeds, crustaceans, molluscs, diadromous salmonids and true marine fishes. Shipments of seed stock for rearing and release were organised by government agencies, so-called 'Acclimatisation’ societies and wealthy individuals. However, the majority of these deliberate attempts at wild stock introductions of marine species were relatively unsuccessful, particularly when compared to euryhaline or obligate freshwater fishes and some freshwater crayfishes that have been deliberately introduced into inland watersheds. However one of the earliest known deliberate introductions was the Pacific oyster Crassostrea gigas, which brought to south-west Europe. Various batches were brought from Japan by Portuguese traders during the 16th Century and released into Portuguese waters, where they established and later became named as Ostrea angulata until genetic studies in 1998 confirmed their true origin. Tens of millions of Crassostrea gigas spat were subsequently imported during the 20th Century into North America, Europe and Australia to establish various closed and open water mariculture operations. Other deliberate introductions of molluscs, which met with varying success, included shipments of European oysters (Ostrea edulis) and blue mussels (Mytilus edulis and M. galloprovincalis) to South America, Australia, South Africa and New Zealand. Some of these introductions lead to invasions, such as the spread of Mytilus galloprovincialis in South Africa. This species has now spread into Namibia replacing the native mussels in rocky intertidal habitats. 1.2.1.1 Mariculture Industry Mariculture is the aquaculture or farming of marine species. The UN’s Food and Agriculture Organization (FAO) defines aquaculture as the “farming of aquatic organisms including fish, molluscs, crustaceans and aquatic plants. Farming implies some sort of intervention in the rearing process to enhance production, such as regular stocking, feeding, protection from predators, etc. Farming also implies individual or corporate ownership of the stock being cultivated…”

14

As the world’s wild fishery stocks continue to decline, aquaculture is one the fastest growing sectors of the global food economy, increasing by more than 10% per year and currently accounting for over 30% of all consumed finfish and shellfish. The majority of mariculture operations are based on introduced species. Most farmed marine fish, including the salmonids, are kept in cages or pens, and fed on pellets manufactured from wild caught forage or bait fish such as anchovies and herring, which are released directly into the pens. Mussels, oysters, clams and scallops do not require feeding (they filter-feed plankton and organic particles in the water column), and are grown on the bottom or on long suspended ropes or racks. Introductions for mariculture purposes should be subject to stringent risk and environmental impact assessments before they are authorised. Such assessments must consider not only the risk and impacts of the introduced species itself, but those of other species associated with it (diseases, parasites and other hitchhikers), and with the food and equipment required. These inadvertent introductions via mariculture operations can occur four ways:

• Escape of pathogens, parasites, commensals or other hitchhikers imported within shipments of crustacean, mollusc or fish seed-stocks which are not subjected to adequate screening and quarantine procedures;

• Self-dispersal of spawn and larvae from unconfined facilities that culture non-native stocks of sessile filter-feeding molluscs (e.g. oysters, blue mussels);

• Escape of the farmed species themselves from open water cages and pens (typically salmonids);

• Introduction of foreign pathogens in frozen or processed fish product, imported to feed ranched tuna, salmonids or other carnivorous fishes.

The level of risk associated with mariculture introductions varies not only with the species, but with the type of operation as summarised in Table 1.2 below. Table 1.2 Concerns related to various types of mariculture facilities. System Typical Species IAS-related Issues Level of Impact Coastal water culture, open and semi-enclosed systems, including onshore facilities.

Oysters, mussels, scallops, clams, abalone, seaweeds

Introduction of non-native spp. (incl. the stock + pathogens, parasites,and various hitch-hikers). Movement of gear can transfer diseases and pests along secondary pathways

Varies with the level of planning and management, particularly seed stock quarantine and gear cleaning.

Net-pens or cages Salmon, sea bass, sea bream, tuna, grouper, snapper

Escapes. Introduction of non-native species and disease agents

Considered High

15

Coastal brackish water ponds

Penaeid prawns and shrimp

Introduction of non-native species, spread of diseases

Considered High

Box 1.3 Case study – Wakame Seaweed The Japanese ‘wakame’ kelp (Undaria pinnatifida) was originally established accidentally in the Mediterranean when it was brought in with oyster shipments in 1971. It was subsequently deliberately brought to the French north-west Atlantic coast for farming in 1983. This mariculture venture ultimately failed but the weed was not removed and began spreading. It was found on the United Kingdom’s south coast in 2000, and has since arrived on the shores of other North European countries.

Undaria pinnatifida Apart from these introductions to west European coastal waters, Undaria has also been unintentionally introduced via hull fouling and/or ballast water to the coastal waters of Argentina, Australia, New Zealand and North America, where it was first discovered in California in the spring of 2000. By 2001 its fertile sporophytes were present in many Californian locations from San Francisco to Monterey Bay harbour (i.e. over a 500 km range and depths from the waterline to 25 m). The ability of Undaria to spread and establish so rapidly can be attributed to its remarkable reproductive and dispersal features. Both the visible seaweed, and the microscopic filamentous gametophytes of this species can readily attach to hard surfaces, including ship’s hulls. In addition, the zoospores are able to delay development in the darkness, and can therefore survive in ballast water tanks for at least several days. These features also explain why almost all eradication and control attempts have been unsuccessful. Once established, this species infests subtidal areas, becoming an ecological pest, and significantly altering the habitats that it dominates.

16

1.2.1.2 Aquaria Releases

pecies are imported for various types of aquarium use. Public aquariums often display

he aquarium pet trade is a worldwide business, with international mail parcels

lthough importation for aquarium purposes does not intend that the species should be

Sspecies from all over the world. Scientific aquariums often make use of foreign species for research purposes. And the aquarium pet industry is based on ornamental species from various seas and oceans, though usually focussed on tropical reef species. Tcontaining aquarium stocks increasing by over 30% in recent years. Small parcels rapidly shipped by express courier companies have provided new pathways. The sources have also increased, particularly with the growth of internet mail ordering services where many types of marine organisms have become widely available (e.g. the invasive aquarium strain of C. taxifolia remains available to aquarium owners via the internet), although several nations are moving to restrict this trade. Aintroduced to the wild, such introductions do occur, either as a result of deliberate releases by owners who no longer want them, or by accidental escapes. The most famous escapes from aquaria have involved the so-called ‘death weed’, which are aquarium-selected, cool tolerant and unusually vigorous strains of the normally tropical green alga Caulerpa taxifolia. The case study below describes an escape from a public aquarium, where the water is circulated / exchanged directly with the sea.

Example

Caulerpa was introduced to the

Caulerpa (Caulerpa taxifolia)

Mediterranean around 1984. Although difficult to prove, it is suspected that it originated in discharges from the Monaco Aquarium. Small fragments of this strain can readily survive to grow into new plants vegetatively. Translocations of escaped plants living in open coastal waters can occur via ballast water, hull fouling and uncleaned fishing, mariculture and SCUBA diving equipment. It continues to spread throughout the northern Mediterranean and has reached the coast of North Africa. It has had a devastating impact on the local native species. It smothers habitats such as the beds of native sea grass that serve as nurseries for many species.

17

The issue of genetically modified organisms (GMO) in the aquaria fish trade has also surfaced, with the recent announcement of ‘red-glowing’ zebra fish. This has been accepted by some American States (e.g. Florida) but rejected for purchase by agencies in others (e.g. California). The issue of future accidental release or discard of GMO fishes into the wild (including transgenic salmonids) is one of growing concern in aquarium management. 1.2.1.3 Coastal Management/ Restoration Coastal management projects often introduce plants or other species for restoration, dune stabilisation or other purposes. Species are often selected for their ability to grow fast and dominate a landscape. These same characteristics may lead to certain species outperforming the original intention, and becoming invasive across beaches and coastlines. The east coast of the U.S. has experienced several problems with coastal invasives, including Giant Salvinia (Salvinia molesta), a small floating fern that invades coastal wetlands, Beach Vitex (Vitex rotundifolia) on coastal dune environments, and Australian Pines (Casuarina obtusifolia) on barrier islands in southern Florida. These and other species can have serious impacts on native flora and fauna, replacing valuable and ornamental coastal species, inhibiting beach use by native species (e.g. turtle nesting) and clogging waterways.

Beach Vitex is a woody vine, native to Korea. It was first introduced by North Carolina State University into the Carolinas in the late 1980s as an ornamental and dune stabilization plant. After being planted on coastal dunes for 10 years, it appears to be the ‘1 in a hundred’ introduced plants that causes problems. It interferes with sea turtle nesting, and forms a monoculture that crowds out sea oats and other native dune species. Moreover, it does not prevent dune erosion, as shown by the under wash of front dunes.

Beach Vitex at DeBordieu Beach, Georgetown County, South Carolina.

Example

18

1.2.2 Unintentional

Most of the known invasive invertebrates have been introduced unintentionally.

Unintentional introductions are those that occur in an unplanned, unpremeditated manner and that enter new geographic areas as hitchhikers or stowaways through pathways involving human activities such as trade, travel and transport. Sometimes unintentional introductions occur in association with intentional introductions, such as the earlier example of Wakame kelp introduced into the Mediterranean via oyster shipments. Similarly parasites and diseases may be associated with translocations of commercial species. The recent rapid growth of world trade, travel and transport has greatly increased the rate of unintentional introductions by effectively breaching natural barriers such as currents, land masses and temperature gradients that once limited the movement of species. Shipping – including other moveable structures such as barges, and oil-rigs - is the dominant pathway amongst unintentional vectors in the marine environment. Various parts of a vessel can function as vectors for marine species transfers (Figure 1.4). Figure 1.4 Vectors associated with a bulk carrier. Ballast water and biofouling/hull fouling are the most significant

pathways for marine bioinvasions.

19

1.2.2.1 Ballast Water Ships are designed and built to move through the water carrying cargo, such as oil, minerals, containers etc. Therefore, if the ship is travelling either without cargo, or with only a portion of its cargo, it does not have sufficient weight to keep it down in the water. Ballast must be taken on board to add the extra weight to keep it stable, and thereby enable the ship to operate effectively and safely. This includes keeping the ship deep enough in the water to ensure efficient propeller and rudder operation, to avoid the bow coming out of the water and to avoid stresses and strains on the hull, especially in heavy seas, which potentially can cause the ship to break up and/or sink. Box 1.4 What is Ballast Water? The International Convention for the Control and Management of Ships' Ballast Water and Sediments 2004, developed under the auspices of the International Maritime Organization (IMO), defines ballast water as follows: “Ballast Water” means water with its suspended matter taken on board a ship to control trim, list, draught, stability or stresses of a ship” Closely associated with the ballast water problem is ballast sediment. When a ship takes on ballast water it also takes on material contained in the water. In turbid or shallow waters this will include solid material. When this material enters the ballast tank it settles to the bottom as ‘sediment’ and may become the host and breeding ground for a variety of aquatic life. The Convention describes ballast sediments as: “Sediments means matter settled out of ballast water within a ship”.

20

When ships were first built by man hundreds of years ago, they carried solid ballast, in the form of rocks, sand or metal. Since around 1880, ships have used water as ballast principally because it is more readily available, much easier to load on and off a ship, and is therefore more efficient and economical than solid ballast. When a ship is empty of cargo, it fills with ballast water. When it loads cargo, the ballast water is discharged. Ballast water is distributed throughout the ship in tanks. These tanks are strategically placed in a variety of formations depending on the structure of the ship. The tanks are generally situated along the side and bottom of the hull (Figure 1.5). Ballast water is taken up through sea chests located on the side and/or the bottom of the ship, with the aid of ballast pumps or by gravity feed. The sea chest intakes are covered with grates or strainer plates preventing large foreign objects from entering the ship’s ballast tanks. However, small organisms and plankton can pass freely through the sea chest. Each ship may carry from several hundred litres to more than 150,000 tonnes of ballast water, depending on the size and purpose of the vessel. It is estimated that up to 12 billion tonnes of ballast water are transported around the world each year. From this it has been calculated that ballast water is responsible for the transfer of between 7,000 and 10,000 different species of marine microbes, plants and animals globally each day. Figure 1.5 Cross-section of cargo vessel showing arrangement of ballast tanks and process

of species transfer While the quantity of ballast water carried by different ships varies considerably, the volume is only one component of risk, as studies have shown that just one cubic metre of

21

ballast water may contain up to 50,000 zooplankton individuals and/or 10 million phytoplankton cells which may potentially establish and become invasive in another part of the world. Most major and several minor phyla have been shown to survive voyages in ballast tanks, and a wide variety of marine species has been introduced by this vector. In fact, most marine species have a planktonic stage in their life cycle and can therefore easily be taken up into ballast tanks (see Figure 1.6 below).

uch as frequency of ship visits and the igin and discharge may be more important.

oinvasions have occurred at ports that receive some very major ports that receive huge

olumes have not been invaded, due to environmental matching and other factors.

allast water was first recognised as a vector for inadvertent marine species introductions 1908, and was occasionally reported and discussed by various workers until the 1985

ated to ne-way’ delivery voyages (requiring more frequent use of large quantities of ballast

too warm or oily for marine fauna to survive, and many countries actively enforce rules

Figure 1.6 Prawn and clam life cycles Other than the volume of ballast, risk factors senvironmental similarity of the ports of orSome of the most spectacular aquatic birelatively small volumes of ballast while v Binpublication of Carlton’s seminal review of trans- and interoceanic ballast discharges. The review highlighted several factors about the rising importance of the ballast water vector, including the progressive increase in the number and speed of trans-oceanic voyages, the additional reduction in journey times owing to the Suez, Panama and other canals, and the increasing use of larger, purpose-built dry and liquid cargo bulk carriers dedic‘owater for the return journey). Since then, the management effort and public attention on ship-mediated bioinvasions have been focussed largely on the primary and secondary pathways provided by this vector. Bilge water, which is water that collects in the bottom (bilge) compartments of a vessel, is usually linked to the suspected translocation of pathogens such as Vibrio cholera strains but is often included with the ballast water for convenience. It may act as a vector for marine plants and animals in some types of fishing vessels, barges and cruising yachts. However the bilge spaces of most types of conventional motor vessel are often

22

constraining the discharge of bilge water into coastal or inland waters as a component of anti-pollution measures. Table 1.3 Examples of marine invasive species introduced via ballast water. The European Zebra Mussel (Dreissena polymorpha) introduced to North America.

Forms dense mats and clusters, covering structures of all types and blocking pipes and ducts associated with industries.

The Comb Jelly Mnemiopsis leidyi

Depleted plankton of the Black Sea leading

introduced to the Black Sea. to collapse of fisheries. The micro-algae Aureococcus anophagefferens introduced to South Africa, and which causes Brown Tide.

Impacts growth rates of cultured mussels and oysters during blooming periods.

1.2.2.2 Biofouling / Hull Fouling

he attachment of organisms to the outside (i er) parts of a vessel, commonly known des sea chests y

test riskw locations without cleaning. The movements of

aller private yachts through regions have also become a serious contributor to this ector for species transfers.

face or to another species during any of its life stages a likely candidate for transfer (e.g. algae, sponges, molluscs, tube worms). Similarly, as

from collecting on their hulls. Journey times were longer an they are for fast modern vessels, allowing for easier attachment of marine

eved by containerisation and modern bulk handling quipment.

T n-watas hull fouling (but which incluof marine invasive species. The greaover long periods and then moved to ne

, anchors etc), is also a significant pathwa is from ships and machinery kept in port

smv Any species that can adhere to a suriswith ballast water, species that land in waters that are suitable for their survival can ultimately establish and become invasive. Examples of species introduced via this pathway are shown in Table 1.4. Historically hull fouling was a prominent vector, as both wooden and steel vessels struggled to keep organisms thorganisms. However, during the 1980s hull fouling was widely assumed to no longer be a significant vector. Arguments in support of this view were the retirement of most wooden hulled trading ships by the 1940s, the development of more efficient anti-fouling systems using tributyltin (TBT), the fast speeds of modern ships and their much shorter turn-around times in port - as achie

23

Table 1.4 Examples of marine invasive species introduced via hull fouling

The Japanese brown alga (Sargassum muticum,) into the Pacific coast of America.

The Japanese brown alga displaces eelgrass beds, which are important nurseries for marine native species.

Th

e black striped mussel

MytAustralia.

Smothers anchors, pylons, buoys, panels ( ilopsis sallei) into northern and chokes water pipes.

Asian kelp (Undaria pinnatifidainto the Mediterranean, Au

) stralia

nd New Zealand.

log

rowth of mussels, and foul fin fish cages, yster racks, scallop bags and mussel

a

Heavy infestations of Undaria can cmarine farming machinery, slow the goropes, which impact upon marine industries.

However du l a significan d ading vessels where the need for smooth hulls (fue drilling platforms and artisanal fishing craf lers, cruising yachts and recreational launches. Eve provided a hull fouling vector by connecting isolated aterways in North America. Many of these vessels are also relatively stationary, whereas modern anti-fouling hull oatings rely on a ‘self-polishing’ action, where species in relatively small abundance are

ept off the hull as the ship moves through the water. Long stationary periods constrain

• filamentous green algae (often Enteromorpha spp.) and turfing red and brown

worms, barnacles, bivalve molluscs, bryozoans and sea squirts (all of which

, it became increasingly apparent t vector in both primary and secon

ring the 1990s that hull fouling was stilary pathways - particularly for non-trl efficiency) is not critical, such as barges,t, as well as many commercial trawn trailered recreational boats have lakes and w

cswthis, as there is greater opportunity for thick biofilms to develop, and for copper- and/or TBT-resistant taxa to colonise leached or damaged coating areas. Moreover, the recent IMO Anti-fouling Convention bans the use of the more toxic anti-fouling hull coatings, such as those containing TBT. Though this may have a positive effect in terms of marine pollution, it also may increase the biofouling problem, at least in the short-term until other acceptable anti-fouling systems are developed. Biofouling communities generally containing species from the following groups:

• biofilms developed by bacteria, cyanobacteria and diatoms

algae • sessile animals including sponges, hydroids, corals, sea anemones, tube-building

24

adhere to suitable substrates and spread via broadcast spawning, with varying durations of larval life)

• mobile benthic and epibenthic animals, including errant polychaete worms, ids and

territorial fishes (esp. Gobiidae and similar forms). This group avoids dislodgment

clinging and grasping to other fouling species or the sheltered parts of the

In dintimatstrongl The diversity of a fouling community typically increases on surfaces which are subject to long perio odecommissioned vessels), and it can include a range of foliaceous green and brown seaweeds, o on location.

ns rough this pathway. There is also growing pressure for regional and/or global

here does fouling occur?

e the ship is under way at sea. When ships remain in harbours or at anchor r prolonged periods, the fouling communities can get a foothold into such hidden

reas, and can be very hard to remove.

ay also occur on a variety of other structures, on fishing and diving gear, and

skeleton shrimps, amphipods, isopods, crabs, nudibranchs, whelks, crino

by either:

- hull

- nestling in microspaces amongst established or dead encrusting species - sheltering within hull apertures and pipework (includes small fishes).

ad ition, there may be a range of commensal species, parasites and pathogens ely accompanying members of the above biota. Many fouling species can adhere y, grow quickly and reach sexual maturity before their eventual dislodgement.

ds f immobility (e.g. drilling rigs, barges, floating docks and laid-up or

sp nges, sea anemones, soft corals and even hard corals depending

In comparison with ballast water, hull fouling as a pathway for invasives has had far less attention dedicated to it. However a few countries (in particular Australia and New Zealand) are slowly putting in place measures to reduce alien species introductiothregulation. Box 1.5 W Fouling on ships does not only occur on the hull but also in sea chests (intakes or discharges for a ship’s cooling system), on propellers, docking block locations, in free flood spaces and pipework systems. These areas can offer protected habitat for some species whilfoa Fouling mfloating debris.

25

Biofouling on vessels: 1

Pipework

Docking Block

Propellers Sea Chests Free Flood Spaces

Hull

.2.2.3 Drifting Marine Debris Marine debris ll known to pose environmental threats due to wildlifnd ingestion, as well as being an unaesthetic factor that influences tourism. The role of uoyant marine debris as a rafting vector for fouling species has been raised by several viewers of the marine litter pro field evidence remains in the infant age. Floating plastic, packing cases and other artificial debris can form surrogate bstrates for natural debris (seaweed rafts, mats of terrestrial vegetation, logs and slow oving whales, turtles and whale sharks). Floating plastic debris may also function in a milar way to ships hulls to transport organisms. Fishing nets which drift ashore after

cific Ocean have been found covered with many marine rganisms, and these may represent a significant drift mechanism in the Pacific Ocean.

is we e entanglement abre blem, but solid stsumsibeing abandoned or lost in the Pao A survey of marine debris in northern New Zealand waters found 60 bryozoan species, 28 of which had not previously been recorded, while other studies have confirmed that plastics and other persistent materials can support various encrusting fouling organisms and associated epibiota, and can also attract a relatively diverse mobile fauna.

26

A 10-year study of stranded shoreline litter (jetsam) confirmed that plastic is the most durable type of litter, is typically more colonized than other debris material and is the dominant component of floating rubbish in most places. It also indicated the marine debris vector can threaten remote islands around the globe such as the Galapagos, as well s the Antarctic, where the amount of available floating material has quintupled due to

marine waters rovide significant pathways for range expansions – not only for distant marine species

the introduction of regional barge traffic, and the facilitation of self-ediated range extensions.

ox 1.6

through permanent fresh to brackish water lakes, the Suez as no locks. Within 30 years of its opening, a number of Red Sea crustaceans and fishes ere found to have transited the canal.

re that the canal has caused the influx of some 300 tropical Indo-acific species into the oligotrophic waters of the Eastern Mediterranean. This

aincreased dumping of litter. The study also found that fouling marine species are capable of entering Antarctic waters by this vector, particularly as barriers such as the water temperatures and the circumpolar divergence (a natural and abrupt sea surface temperature barrier) continue to change due to the global warming trend. Reducing the prevalence of synthetic materials entering the oceans requires changes in the awareness and attitudes of coastal communities and industries, plus better implementation of existing international marine pollution (MARPOL) regulations by Port and Flag States. 1.2.2.4 Canals, Seaways and Internal Waterways Canals and other navigable waterways which link otherwise unconnectedpbut also for regional natives which had not reached previously isolated water bodies. Although more common in freshwater systems, the opening of new canals and seaways has led to various waves of marine introductions as a result of shortened international shipping routes, m BLessepsian Migrations Some of the most famous canal-induced introductions are the so-called ‘Lessepsian migrations’ into the Eastern Mediterranean via the Suez Canal (named after the French engineer who designed and managed construction of the canal). The opening of the Suez Canal in 1869 connected the Red Sea with the Mediterranean. Unlike the Panama Canal which has locks and passes hw More recent estimates aPnorthward migration has been associated with the canal’s predominant northerly current, the ability of the Red Sea taxa to tolerate winter conditions in the Levantine basin and the relatively low biodiversity of the Eastern Mediterranean. Not all introductions into the Mediterranean are due to the canal. For example, some 5% of the Mediterranean’s current inventory of molluscs comprise non-native species introduced to its western half by ballast water, hull fouling and other vectors.

27

Completion of the Welland Canal between Lake Ontario and Lake Erie provided a bypass

freshwater discharge as ell as climate variations, is considered to have assisted the survival of these species.

s’ ulls, this link has still significantly contributed to the increased rate of marine

.2.2.5 Range Expansions in a Changing World

inese mitten crab in German coastal areas during the 0th Century.

in native populations, including the opulation booms of the Northern Pacific seastar (Asterias amurensis) within its endemic

readily promote high levels of larval survivorship, settlement and cruitment success. Several studies have shown how small climate fluctuations may

around Niagara Falls, allowing the anadromous sea lamprey and other marine invaders to expand their spawning and feeding areas into many parts of the upper lakes and river systems. Adult sea lampreys are large (60-90 cm) and voracious blood suckers of many native fish including salmonids. They rapidly established and decimated local populations of lake trout and other species by this feeding behaviour. The Great Lakes seaway also provided the route for other brackish and marine biota, of which the most well known is now the zebra mussel, Dreissena polymorpha. Increasing salinity of the Great Lakes from the 1940s to 1970s, in part due to decreasedw Other canals which have caused significant invasions include those forming the Euro-Asian waterways (e.g. the Dnepr and Volga-Dom systems), and the Parana-Tocantis-Amazonas river links in South America. The opening of the Panama Canal in 1914 connected the West Atlantic/Caribbean with the East Pacific. This canal has a system of locks and passes through permanent fresh to brackish water lakes, thereby reducing the ability of species to successfully transit through natural range expansion. However, by significantly reducing inter-ocean travelling times, and thereby increasing survival of species in ballast tanks and on shiphintroductions of the 20th Century. 1 Natural fluctuations and cycles in solar intensity, planetary tilt, ocean currents and weather systems, together with human activities such as urbanisation and fossil fuel burning, combine to cause regional and global climate variations and change over scales of decades and longer. It has been speculated that regional cycles in rainfall and thermal extremes help explain why some introduced species have undergone ‘boom-bust’ cycles in local populations, such as the Ch2 Sudden changes in abundance are not uncommonprange, and the Crown of Thorns starfish (Acanthaster planci) in the tropical Indo-Pacific. Overfishing of groupers, the natural predator of Acanthaster larvae, also contributes to these population booms. These major but apparently natural swings in population size have been related to fluctuations in weather patterns, water currents, nutrients and other planktonic conditions, as these may re

28

generate large changes in marine communities through alteration of predation rates and food-chain structure. In the case of natural range expansions associated with the marked global warming trend over the past century, these have been reported for the Ligurian Sea in the Mediterranean,

e English Channel and the coastal waters off North Carolina, California and Western

) off south-east Australia, with net southward retreat being ccelerated by infill of Undaria pinnatifida.

in the world’s oceans. Though the global arming trend may be tied to human activities, the management of this phenomenon is

.3 Impacts

uman health.

al impacts

remove.

thAustralia. Recent (20th Century) poleward expansions of subtropical and tropical marine and coastal species are well documented (including corals, molluscs, fishes, seabirds and coastal plants) and often linked to other evidence for global greenhouse gas warming. Conversely, there has been a retreat of native cold water forms as coastal water temperatures rise. This includes the southward displacement of the giant kelp beds (Macrocystis pyriferaa The fossil record shows the marked tendency for major marine species radiations to involve movement and dispersal of warm-water forms to cooler water regions, rather than vice versa. As with many terrestrial biota, these radiations have occurred on many occasions, the last being the rapid Holocene re-invasion and infill of temperate and boreal regions by taxa which had been compressed into narrow temperate and subtropical belts during the last ice age. All such natural, non-human-mediated range expansions are considered part of the ongoing evolution of biogeographic patternswoutside the scope of this course. However, the facilitation role played by global warming in marine species invasions should be taken into consideration when researching species’ invasiveness and new species records, and when making management decisions to intentionally introduce new species. 1 The introduction of alien organisms into a new environment can have serious negative consequences for the environment and local biodiversity, for industries and users of natural resources, and also for the health and welfare of those associated with the affected marine systems. While there can be many direct and indirect impacts of invasive marine species, the principal consequences can be grouped into three main categories - ecological, economic and social and h

1.3.1 Ecologic Ecological impacts occur when the local biodiversity of the area and/or the ecological processes are altered by the invasive species. While the initial impacts may be minor and near-invisible, as the population increases over time, the impacts will increase in severity. Moreover, once a species has been introduced, it is very difficult if not impossible to

29

Ecological impacts may include:

• Competing with native species for space and food

Preying upon native species

• Displacing native species, reducing native biodiversity d even causing local extinctions

v on society. These include both losses as a on of reduced productivity, and costanagement of invasive species. For example, it is estimated that the costs of controlling

ll invasive species (marine and terrestrial) in the USA alone exceeds 138 billon dollars nnually.

•

• Altering habitat of other species

• Altering environmental conditions (e.g. decreased water clarity)

• Altering of the food web

an

1

Example

Asian or ‘wakame’ Kelp (Undaria pinnatifida)

Native to Northern Asia, it asSouthern Australia, New Zealand, the West Coast of USA, Europe and rgand spreads rapidly, both vegetativelythrough dispersal of spore t dalgae and marine life, alters haecosystems and the food web. It may affect commercial shellfish stocks through space competition and alteration of habitat. (See also Box 1

w introduced to

A entina. It grows and

s. I isplaces native bitat,

.3)

.3.2 Economic impacts

asive species have major economic impacts sequence

Inc s incurred for the prevention and maa

30

More specific examples of economic impacts include:

jelly (see Box Example on next page)

• Impacts on aquaculture (including closure of local facilities), especially from introduced harmful algal blooms and diseases of cultured species (eg. white spot disease on shrimp)

oastal infrastructure, facilities and

•

monitoring, testing, diagnostic and

•

costs.

• Reductions in fisheries production (including potential collapse of the fishery) due to competition, predation and/or displacement of the fishery species by the invading species, and/or through habitat/environmental changes caused by the invading species Eg. the comb

• Physical impacts on cindustry, especially by fouling species, and secondary impacts through coastal erosion e.g. the zebra mussel (see Box Example on next page)

Reduction in the economy and efficiency of shipping due to fouling species;

• Impacts or even closure of recreational and tourism beaches and other coastal amenity sites due to invasive species (e.g. physical fouling of beaches and severe odours or health impacts from algae blooms )

• Costs associated with coastal management activities necessitated by invasive species eg. stabilisation of coastal dunes, and restoration of locally extinct or depleted biodiversity;

• Secondary economic impacts from human health issues associated with introduced pathogens and toxic species, including increasedtreatment costs, and loss of social productivity due to illness and even death in affected persons;

Secondary economic impacts from ecological impacts and biodiversity loss;

• The costs of responding to the problem, including research and development, monitoring, education, communication, regulation, compliance, management mitigation and control

31

Example

The comb jelly, Mnemiopsis leid , ithe North American Atlantic coast.recorded in the Black Sea was 1

yi s endemic to It was first

in 982, where it became well established, occ gnumbers and changing the whole peweb. It also had a devastating effect ofisheries of the Black and Azov

sheries target zooplanktivorous fish species such anchovy, Mediterranean horse mackerel and rat (Black Sea) and in the Sea of Azov, the Azov chovy and Azov kilka. Mnemiopsis also feeds on oplankton, and its presence lead to a massive

ailability of food for the fish. As a sult, t eries, collectively worth proximately $500 million per year, all collapsed.

urin in massive lagic trophic n the pelagic Seas. These

fiasspanzodecline in the av

he fish

reap

Comb jelly (Mnemiopsis leidyi) Landings of anchovy dropped to one-third of their previous levels, and many fishermen abandoned fishing. The situation has improved in recent years as a result of another accidental introduction – a second species of comb jelly which preys on Mnemiopsis, and which has lead to a decline in its numbers.

Example

Zebra mussel (Dreissena polymorpha) Photo: S. Olenin

Native to Eastern Europe (Black Sea), the zebra mussel was introduced to western and northern

urope, including Ireland and the Baltic Sea andEt

to e eastern half of North America (Great Lakes). It an encrusting species that forms large clumps of ussels grouped tightly together fouling all ailable hard surfaces in mass numbers. It splaces native aquatic life and alters habitats, food ebs, and ecosystem functions. It causes severe uling problems on infrastructure and vessels and

hismavdiwfoblocks water intake pipes (Figure 1.8), sluices and

rigat Economic costs for attempting to ear els from industrial facilities in the SA alone are estimated around US$ 750 million to

illion between 1989 and 2000 (O’Neil, 2000).

ir ion dikes. zebra musscl

U1 bThis invasion and its costs are ongoing and escalating, and now threatening the west coast of North America where massive prevention programs have been put in place.

32

Figure 1.8 Zebra mussels clogging a pipe

.3.3 Public Health Impacts

iven the magnitude of ongoing ballast water transfers, the large-scale movement of icro-organisms by ships has commanded the attention of both epidemiologists and vasion biologists.

ome cholera epidemics have been directly associated with ballast water discharges. hile Vibrio cholerae and other potential pathogens may be norma

igh enough concentrations to cause uman health problems. However, with expanding world trade and an increasing number f ships moving among international ports, the transfer of microbes could well be the

most insidious threat related to ballast water discharge.

addition to bacteria and viruses, ballast water can also transfer a range of species of

isoning, which can cause severe illness and even death in humans. he threat of health impacts also forces the closure of mariculture facilities rearing filter-

1 Gmin SW

l constituents of coastal waters, they do not ordinarily occur in hho

Inmicroalgae, including toxic species that may form harmful algal blooms such as ‘red tides’. The public health impact of these outbreaks is well documented and includes paralytic shellfish poTfeeding shellfish species which tend to accumulate the micro-algae and associated toxins.

33

Example

Cholera (Vibrio cholerae) Photo: G. Casale

In 1991 a freighter from South Asia emptied its bilges off the coast of Peru, introducing a strain of cholera that reproduced well in the unusually warm coastal waters with abundant pollution. This lead to an epidemic which began simultaneously at three

parate seaports. The bacterium made its way into ellfish and through this, to humans, and spread in epidemic killing a reported 5,000 people. The chlorinated water supply in Peru’s cities then rried the cholera strain and delivered it into

seshanuncapeople’s houses (Dimijian, 1999). The epidemic

ten outh America affecting more than millio reportedly killing more than n thousand by 1994.

ex ded along Sn people anda

te

Example

Toxic algae (red/brown/green tides) Photo: Y. Fukuyo

Several species of toxic algae have been transferred o new areas in ship’s t

aballast water and sediments

d have established in the new environments. They ay form harmful algal blooms (HABs). epending on the species, they can cause massive

f marine life through oxygen depletion, lease of toxins and/or mucus. They can foul

nmDkills orebeaches and impact heavily on tourism and

creation. Some species may contaminate filter-eding shellfish and cause fisheries to be closed. uma an be affected because HABs can use ning (ciguatera) and/or shellfish isoning.

refeH n health c

fish poisocapo The health and ecological effects of HABs usually have economic costs, either to prevent a HAB from occurring or responding where a HAB has taken place. In the period 1987-1992, the average economic costs of HABs to human health in the United States alone was estimated at $22 million per annum; shellfish poisoning costing $1 million and ciguatera poisoning $21 million.

34

Example

Figure 2.9: Dense carpet of Caulerpa taxifolia on the Mediterranean seafloor (Alexandre Meinesz)

The green seaweed (Caulerpa taxifolia) is a good example of an IAS with multiple types of impacts. It has rapidly spread through the Mediterranean Sea including the North African coast, causing ecological and economic devastation. It is reported to have harmed tourism and pleasure boating, devastated recreational diving, and had a costly impact on commercial fishing, both by altering the distribution of fish as well as creating a considerable obstacle to net fisheries. The dense carpet that this species can form on the bottom could also stop the establishment of juveniles of many reef species.

1.4 Predicting Invasions

he ability to predict invasions would offorts to prevent and manage them. Coying to get a better understanding of the f

cies introducti

T bviously have major advantages in terms of

nsiderable effort has therefore been put into actors,

on, which contribute to the suhese factors include the characteristics of the nd also the state of the ceiving environment.

.4.1 Species Characteristics

mpiled various lists of species’ traits and characteristics in hich are likely to spread and cause harm if introduced.

Duration and toughness of the dispersal stages. Species that can grow and mature rapidly, and reach reproductive age quickly will have an advantage in establishing

le niche.

etr other than the strength of the vectors of

ccess of a potential invading species. speT species itself are 1 Invasion biologists have coheir attempts to predict wt

Characteristics which are considered to be indicative of invasiveness include:

• A widespread distribution and abundance in their native range. • Reproductive mechanism/s and fecundity. Broadcast spawners, or species with

high reproductive capacities are able to build populations quickly, increasing the chance for establishment in their new habitat.

•

a population in an availab

35

• High capacity for tolerance and adaptability of environmental conditions. Species able to tolerate or adapt to local ranges in temperature, salinity and other physical factors will be more likely to survive and proliferate in new environments.

• Effective dispersal mechanisms. Species that can spread quickly once established

How vdisplayenviron ays available. Therefore predictions versus outcomopinion The nnot the of water temperature/ sali y is because

any marine and estuarine species have wide thermal/salinity tolerances. On the other and, the ability for marine species to occupy divergent habitats is constrained by the

.4.2 Environmental Conditions & Disturbance

orted from a range f areas such as the north-west Black Sea, San Francisco Bay, Port Phillip Bay Melbourne) and Mediterranean localities, including the Berre, Thau (Hérault) and

relatively low native marine biodiversity, such as the Hawaiian Islands, Eastern

in a new environment are more likely to become invasive. • The ability to use a wide range of sources to meet their dietary needs.

e er the characteristics exhibited by a species in its native range can differ to those ed by its populations in invaded areas. In addition, key life cycle and mental tolerance data are not alwes have not been reliable, and assessments which rely heavily on subjective expert can generate a false sense of security.

o e factor which has shown good correlation with predicted outcomes is whether or species in question has been invasive elsewhere. Matches

nit ranges are also useful, but by themselves are not as reliable. Thismhpowerful hydrodynamic, sedimentary and physico-chemical processes that operate in marine environments. Therefore environmental matching methods can also be useful tools in predicting the marine bioinvasion potential of certain species. 1 There is also increasing support for the concept of ‘invader friendly’ receiving environments, since the highest numbers of marine introductions are typically associated with estuaries, harbours or bays dominated by artificial, disturbed and/or eutrophic habitats. Reduced native biodiversity and increased vacant niche space due to eutrophication, over-fishing (which also increases nutrient availability via reduced grazing pressure and standing biomass), land reclamation/urbanisation, river damming, etc, have been linked to the invasion ‘hot-spots’ and ‘meltdowns’ repo(Venice lagoons. Two other features of the receiving environment have been associated with an increased propensity for both aquatic and terrestrial introductions:

• The degree of biogeographic isolation and associated percentage of endemic species. Marine environments with low biogeographic connectivity and high endemicity include those in the Ponto-Caspian, Eastern Mediterranean, Laurentian Great Lakes, southern Australia, New Zealand, Hawaii and parts of the American Pacific coast. Biogeographically isolated regions which also have

36

Propagule - a part of an organism/species from

which another organism/species can be

Propagule pressure – The likelihood of the blishment of an alien species increases with the ber of individuals introduced and the frequency

ntroductions.

produced (including seeds, roots, rhizomes for plants

and eggs, larvae, pupae for animals.

h facilitate successful marine introductions.

both sides of the Australian continent. Although some reasons have been put forward, it is still unclear why

1.4.3 Other f

- estanumof i

- ack of natural enemies (e.g. pathogens,

iseases, predators or competitors) - When a ed to a new location outside its

native range the predators, diseases or other species

Cur marine i stly likely to establish, spread and cause harm may be ranked as follows:

erest i d e that s

rological characteristics and region and those of the natural and other

introduced ranges of the species of interest. • The degree of ‘invader friendliness’ of the waters where the inoculations occur.

The number of recently established marine invasive species

ive assemblages o The presence of depauperate native communities owing to eutrophication,

pollution, over-fishing, river dams or other disruptive processes

Mediterranean and Baltic Sea, have also been considered to provide vacant niche space whic

• Latitude. The rise in marine invasive species numbers per increment of latitude

has been noted globally, and specifically along

temperate regions may be more prone to marine bioinvasions than tropical and polar coasts.

Other factors

actors, which may help alien species to establish in new ranges, include:

Ldspecies is transferr

that help control it may be left behind. 1.4.4 Current Practice

rent best predictors for identifying which and where ntroductions are mo

s potentially invasive anthe species of interest ha

• Existing evidence for suspecting the species of int

capable of causing harm (e.g. documented evidencinvaded and caused demonstrable harm).

• The degree of similarity between the climate, hydmarine habitats of the receiving

For example: oo The percentage of artificial, heavily modified or disturbed habitats that

offer vacant niches due to absence or immaturity of nat

37

• The range of secondary pathways available (i.e. number and frequency of local vectors and their routes that can assist regional spread) The presence of biogeographically isolate• d marine communities containing a high

• spect to tropical/polar latitudes (20-

However th There are also factors tha fpredict. For x ch controls pothese reason t species of con n

rade liberalisation is a relatively recent phenomenon that has transformed the way in hich the world economy operates. Exports from distant countries are now quickly and

fficiently tra re in the world in quantities unheard of a century go. For exa o 6.2 trillion at the globae advent of

cross the gumbers and m ing under increasing human pressure. This rapid rowth in the movement of people and their goods are facilitating the transportation of ousands of organisms around the world.

ecognition of these facts, and of the impacts caused by invasive species, has led to the

percentage of endemic taxa and/or offering naturally vacant niche space owing to relatively low biodiversity The location of the receiving waters with re60o)

ere is insufficient evidence to adequately quantify these trends. t in luence invasiveness on a more ‘case by case’ basis which are difficult to e ample, the absence of one or more pathogens, parasites or predators whipulations in the native range by reducing fitness, fertility and/or longevity. For s here remains no substitute for careful biological research on any

cer , both in its natural and invaded habitats.

1.5 The Need for IAS Management

Precautionary approach

the potential impacts; every alien species should be considered as potentially invasive until convincing evidence indicates that it presents no such threat or

Given the uncertainty associated with predicting species invasiveness and

more simply, every alien species must be considered “guilty” of invasiveness until proven otherwise.

Twe nsported to almost anywhea mple, the value of worldwide exports grew from US$192 billion in 1965 t

in 2000. As the primary mode of transport for these goods, it is estimated l shipping industry will more than double by the year 2020. Moreover, with the internet, even private individuals can easily order almost anything from lobe. Similarly, people are moving around the world in ever-increasing

ore remote places are com

$ththangth Rdevelopment of a variety of strategies for their prevention and control. These strategies will be the focus of the next modules.

38

igure 1.12: People and vehicles are moving around the globe more than ever.

F

As trade, travel and transport grow, so too, are the number of IAS introductions.

Figure 1.13: World shipping routes. Most used routes are shown in yellow with least used in white.