Angela Whitley

Coastal Environments: CIAM 6117

Oct 7 2015

What are Seagrasses? Seagrasses are flowering plants which evolved from

terrestrial plants and grow entirely in shallow marine/brackish environments.

They are categorized as vascular, with a network of xylem and phloem that transport nutrients and dissolved gases throughout their systems.

Seagrasses possess roots, leaves, and underground stems called rhizomes that hold them in place.

They produce flowers, seeds and fruit.

Seagrasses are not “Grasses” and are not to be confused with Seaweed (Macroalgae).

Seagrass vs Seaweed Seaweed/Algae are from the phylum Protista

a taxonomic group that includes protozoans, prokaryotes, fungi, sponges, and algae

More primitive and simpler than seagrass and do not have a true root system.

Holdfast anchors plant to a hard surface

Use diffusion to extract nutrients from the water

Seagrass vs Seaweed/Algae

Distribution

Where does seagrass grow?

Soft bottomed bays, lagoons, estuaries and coastal waters from the mid intertidal region to depths of 60 meters.

• Various combinations of temperature, salinity, waves, currents, depth, substrate and day length parameters determine success of growth.

• These meadows may be monospecific or may consist of multispecies communities.

Global Distribution

Local Distribution There are less than 60 known species of seagrass

worldwide

10 known species in the Caribbean

The most dominant in Puerto Rico are:

Turtle Grass (Thalassia testudinum)

Manatee Grass (Syringodium filiforme)

Factors Affecting Distribution Natural disturbances

waves, extreme tidal fluctuations, hurricanes, and animal foraging

Anthropogenic disturbances

eutrophication

urbanization

sedimentation

propeller scarring & anchoring

overfishing

Seagrass Functions Decrease wave action and reduce shoreline erosion Water quality: Filter the water and reduce sedimentation by trapping

suspended particles. Produce oxygen Filter nutrients that come from land-based industrial discharge and

storm water runoff before these nutrients are washed out to sea. Support high faunal and algal diversity Foraging grounds for several endangered marine species

Manatees, sea turtles and a few species of marine birds

Primary production Primary production is the production of chemical energy in organic

compounds by living organisms. The main source of this energy is sunlight.

Nursery/Habitat for many commercially important fish and invertebrates

The complexity of seagrass habitat increases when various species of seagrasses grow together.

Recruits diverse flora and fauna living within

Habitat and Nursery As a habitat, seagrasses act as nurseries and provide

food and shelter to many commercial and recreational fishery species, as well as numerous invertebrates that are produced within, or migrate there.

The dense network of

rhizomes discourage predators from digging up infaunal pray.

Epiphytic organisms and small macroalgae attach themselves to seagrass blades.

Contribute to food webs directly through organisms grazing on seagrasses or indirectly through death as detritus.

In some systems epiphytes account for up to 30% of ecosystem productivity (Penhale 1977, Morgan & Kitting 1984, Heijs 1984).

Nursery Seagrass communities make excellent nurseries for

commercial and recreational fishery species and many invertebrates by providing food and protection.

Seagrass leaves are also ideal for the attachment of eggs (mollusks).

Seagrass is used as an intermediate habitat for migrating fish from mangroves to coral reefs.

Many fish species (Snapper/Grunts) spend their juvenile life stages in seagrasses and move to coral reefs to complete their adult lives.

However, some fish (seahorses/lizardfish) can be found their entire lives there.

Habitat Loss Vessel Traffic

• Dredging, propeller scarring, anchoring which break rhizomes and destroys root systems

An example of the affects of physical damage Seagrass offers refuge from predators, and experiments

have shown that some shrimp species become more vulnerable when that cover is destroyed.

Why does that matter?

The scarring was found to modify species dominance for certain numerically abundant shrimp taxa (Alpheus normanni and Trachypenaeus sp.) who are associated with bare sand patches (Holmquist 1992).

It can take up to 5 years for seagrass communities to recover from propeller damage, if they recover at all.

Coastal Construction

The development of marinas and docks destroys seagrass beds and increases boat traffic.

Eutrophication

Through sewage pollution and/or topsoil runoff an increased amount of nutrients are introduced into the water.

This fosters epiphytic microalgae growth on seagrass leaves, reducing sunlight penetration and productivity of the seagrass.

Why Conserve Seagrass? Seagrass/algae beds are rated the 3rd most valuable

ecosystem globally (per hectare), only preceded by estuaries and wetlands. (www.seagrasswatch.org)

1 Hectare = 2.47105381 Acres

Within seagrass communities, a single acre of seagrass can produce over 10 tons of leaves per year and support as many as 40,000 fish and 50 million small invertebrates. (Smithsonian,www.sms.si.edu)

Due to such high productivity, biodiversity and sensitivity to changes in water quality, seagrasses have become important indicators of the overall health of coastal ecosystems. Some researchers compare them to tropical rainforests.

The Dollar Value of Seagrass

While nutrient cycling and primary production in seagrasses tends to be seasonal, annual production in seagrass communities rivals or exceeds that of terrestrially cultivated areas.

Example: Florida has 2.7 million acres of seagrass

Supports commercial and recreational fisheries which in turn benefits the state’s economy

In 2000 Florida’s Department of Environmental Protection reported that the seagrass communities supported commercial harvests of fish and shellfish valued at over 124 billion dollars.

The FDEP estimated that each acre of seagrass has an economic value of $20,500/yr which = 55.4 billion dollars annually.

In Fort Pierce, FL the 40 acres of seagrass within the Fort Pierce Inlet alone are valued at over $800,000 annually. When projected across St.Lucie County’s 80,000 acres of seagrass, this figure

increases to 1.6 billion dollars per year.

Smithsonian Marine Station at Fort Pierce: http://www.sms.si.edu/IRLSpec/Seagrass_Habitat.htm

Conservation Efforts in Puerto Rico The Puerto Rico Seagrass Fund was established to implement

seagrass conservation projects in Puerto Rico. With the support of a Fund-awarded grant, an Initial Assessment was completed in December 2014 identifying seagrass protection and restoration opportunities based on observed anthropogenic impacts to seagrass and recommending priority y conservation locations and strategies.

The Navigation and Aquatic Safety Law (2000) and Regulation 6979 of 2005 Established measures to protect marine flora and fauna from

recreational and other human activities. Article 24 of Regualtion 6979 prohibits mooring any vessel in

mangroves, coral reefs, or seagrass beds. Law 147 of 1999 prohibits the removal, mutilation, or destruction of

coral reefs and associated systems including mangroves.

Violations of these laws result in fines between $250-$10,000 per infraction.

Unfortunately, the absence of regulation, enforcement and the general public’s deficiency of understanding has resulted in increases in seagrass damage despite the existence of laws and regulations protecting them.

Discussion Like Florida, could Puerto Rico possibly profit from

seagrass communities?

What could be some possible outcomes of having less manatees and sea turtles along the coasts of Puerto Rico due to seagrass habitat loss?

Does the reduction of seagrass areas have a huge impact on the deep or open ocean?

What are some creative ways to get people involved and more knowledge about seagrass ecosystems and conservation?

References

Amy V. Uhrin1, Jeff G. Holmquist (2003) Effects of propeller scarring on macrofaunal use of the seagrass Thalassia testudinum. Mar Ecol Prog Ser Vol. 250: 61–70 F. Short, T. Carruthers, W. Dennison, M. Waycott (2007) Global seagrass distribution and diversity: A bioregional model. Journal of Experimental Marine Biology and Ecology Vol 350: 3–20. Alfonso Aguilar-Perera, Richard S. Appeldoorn (2007) Variation in juvenile fish density along the mangrove–seagrass–coral reef continuum in SW Puerto Rico. Mar Ecol Prog Ser Vol. 348: 139–148 Nagelkerken, S. Kleijnen, T. Klop, R. A. C. J. van den Brand, E. Cocheret de la Morinière, G. van der Velde (2001) Dependence of Caribbean reef fishes on mangroves and seagrass beds as nursery habitats: a comparison of fish faunas between bays with and without mangroves/seagrass beds. Mar Ecol Prog Ser Vol. 214: 225–235 Robert J Orth, Tim J. B. Carruthers, William C. Dennison, Carlos M. Duarte, James W. Fourqurean, Kenneth L. Heck Jr., A. Randall Hughes, Gary A. Kendrick, W. Judson Kenworthy, Suzanne Olyarnik, Frederick T. Short, Michelle Waycott, Susan L. Williams (2006) A Global Crisis for Seagrass Ecosystems. BioScience Vol. 56 (12): 987-996 Brigitta I. van Tussenbroek, Jorge Corte´ s, Rachel Collin, Ana C. Fonseca, Peter M. H. Gayle, Hector M. Guzma´n, Gabriel E. Ja´come, Rahanna Juman, Karen H. Koltes, Hazel A. Oxenford, Alberto Rodrı´guez-Ramirez, Jimena Samper-Villarreal, Struan R. Smith, John J. Tschirky, Ernesto Weil (2014) Caribbean-Wide, Long-Term Study of Seagrass Beds Reveals Local Variations, Shifts in Community Structure and Occasional Collapse. PLOS ONE Vol 9: Issue 3 Jorge García-Sais, Richard Appeldoorn, Tim Battista, Laurie Bauer, Andy Bruckner, Chris Caldow, Lisamarie Carrubba, Jorge Corredor, Ernesto Diaz, Craig Lilyestrom, Graciela García-Moliner, Edwin Hernández-Delgado, Charles Menza, Julio Morell, Anthony Pait , Jorge Sabater, Ernesto Weil, Ernest Williams, Stephanie Williams (2014) The State of Coral Reef Ecosystems of Puerto Rico Ernesto Otero, Lisamarie Carrubba (2006) Characterization of Mechanical Damage to Seagrass Beds in La Cordillera Reefs Natural Reserve. Task CRI-10 Conservation and Management of Puerto Rico’s Coral Reefs Final Report Jose Gonzalez Liboy (2005) An Examination of the Present Condition of Seagrass Meadows in La Parguera, Puerto Rico. Library Caribbean Fishery Management Council. Ernesto Otero, Yasmín Detrés, Roy Armstrong, Stacey Williams, William J. Hernández López (2015) Puerto Rico Seagrass Fund – Initial Assessment Integration of Field, Aerial Photography and Water Quality Measurements for the Assessment of Anthropogenic Impacts and Stressors in Southern Puerto Rico Final Report I. Nagelkerken, C.M Robers, G. van der Velde, M. Dorenboch, M.C. van Riel, E. Cocheret de la Moriniere, P.H. Nienhuis (2002) How important are mangroves and seagrass beds for coral-reef fish? The nursery hypothesis tested on an island scale. Mar Ecol Prog Ser Vol. 244: 299–30 K. L. Heck Jr., G. Hays, R. J. Orth (2003) Critical evaluation of the nursery role hypothesis for seagrass meadows. Mar Ecol Prog Ser Vol. 253: 123–136 Seagrass Watch: http://www.seagrasswatch.org/seagrass.html Smithsonian Marine Station at Fort Pierce: http://www.sms.si.edu/IRLSpec/Seagrass_Habitat.htm National Fisheries and Wildlife Foundation: http://www.nfwf.org/seagrassfund/Pages/initial-assessment-rfp.aspx