Potential Fishery Impacts to Alaska from a Marine Invasive Species: the

colonial tunicate Didemnum vexillum

Linda Shaw, National Marine Fisheries Service

American Fisheries Society, Alaska Chapter October, 2012

Klas Stolpe Juneau Empire

● What are Invasive Species and their Impacts? ● What are Risk to Alaska Fishery Resources? A Current Example for Alaska: Didemnum vexillum The organism and its discovery in Alaska What are its Fishery Impacts Elsewhere Alaska Scallops, Herring, Abalone, Groundfish ● Where could Dvex infest Alaska? Habitat Suitability Model Maps

"Invasive species" means an alien species whose introduction does or is likely to cause economic or environmental harm or harm to human health.

"Alien species" means, with respect to a particular ecosystem, any species, including its seeds, eggs, spores, or other biological material capable of

propagating that species, that is not native to that ecosystem.

*Executive Order 13112 signed by President William Clinton on February 3, 1999

What is an “Invasive Species”? *

Example: The Alien Monster Not Native To Earth, i.e. from Outer Space + Threat to Human Health = Invasive Species

● Out-Compete, Predate On and Avoid Predation by Native Organisms ● Often Tolerate and Thrive in Disturbed or Polluted Habitats ●May be present for years in a Lag Phase before an environmental “trigger” explodes their populations

Impacts of Invasive Species

Lovett-pinetum.org

A CURRENT EXAMPLE FOR ALASKA: Didemnum vexillum

aka Glove Leather Tunicate/Rock Vomit/Dvex *A Colonial Tunicate (aka Sea Squirts): animals, hemichordate * Cellulose tunic covers body of membrane sac containing gills,

heart, nervous system * Reproduce by budding (asexual) and larvae (sexual) adults settle and filter food (incurrent and excurrent siphons)

“A bit like a balloon over a balloon that has an innie and outie” Stephanie Roscoe, Natural History Magazine

Individual Zoids combine to form colony and share excurrent siphons

Sea peach: solitary tunicate native to Alaska

Didemnum vexillum or Glove Leather Tunicate/Rock Vomit

Discovered In Whiting Harbor, Sitka, Alaska in June, 2010 as part of a marine invasive species “Bioblitz” event.

Genetic Confirmation of species by Sarah Cohen, SFSU, August, 2010: Suspected source is Japan through British Columbia

Puget Sound Diver Demonstrating Origin of Name “Rock Vomit” www.pnwscuba.com

Didemnum vexillum or Glove Leather Tunicate/Rock Vomit •  First Known Location in AK

Whiting Harbor, Site #10

Whiting Harbor Sitka, Alaska

Dvex in Sitka discovered fouling both an abandoned oyster farm (dock structures and hanging lantern nets)

Fouling oyster cage in Whiting Harbor Sitka

And on natural “hard” surfaces

rock, brown algae and intertidal

Photos Courtesy Alaska Department of Fish and Game and Marnie Chapman

DVEX IS A PROBLEM WORLDWIDE

Fouling mariculture gear in British Columbia

Suffocating mussels In New Zealand,

Photos: Puget Sound Partnership, Paul Barter,

And Puget Sound

DISCOVERY COINCIDED WITH BREAK UP OF INFESTED DOCK

Photo Source: Marnie Chapman

Interested Parties: ADF&G Lead, UAS-Sitka, Sitka Sound Science Center, Smithsonian Environmental Research Center, NOAA, USFWS, Sitka Tribe, SFSU-Tiburon, AmeriCorps, US Coast Guard, City of Sitka

First contain, then eradicate. ADF&G has removed much of the docks and lantern nets from the abandoned aquafarm for upland disposal in the fall of 2011. (USFWS funding) ADF&G is continuing to survey Dvex distribution in Whiting Harbor and has 500K in funding from the Legislature to continue control and eradication.

Interested Parties: ADF&G Lead, UAS-Sitka, Sitka Sound Science Center, Smithsonian Environmental Research Center, NOAA, USFWS, Sitka Tribe, SFSU-Tiburon, AmeriCorps, US Coast Guard, City of Sitka

Reduce possibilities for reintroduction Source may have been dock material from British Columbia. Use Permitting and Education to Manage movement of infested docks and aquaculture equipment.

Potential for Explosive Growth

Dvex Strategy: Learn More about the biology of Dvex In Whting Harbor

6/24/11

9/1/11 (10 weeks later)

Some Concerning Characteristics: Smothers marine life and aquaculture gear by

overgrowing them. Acidic tunic and secretes cytotoxins from

commensal bacteria. Toxins and acidity may prevent other life from growing on it.

“Ecosystem Engineer” that glues pebble and

cobble together to change seafloor from a 3D to 2D environment

Creates a water flow barrier to sediment Mercer et al. (2009)

Potential Fishery Impacts Elsewhere: Case Study Georges Bank

Infested New England’s intertidal in the 1980s, then jumped to Georges Bank in 2002 By 2007 has expanded to over 230 square miles of seabed at water depths of 45-65 m (148 to 213 feet) with 50 – 90% coverage of the bottom (Valentine et al. 2009).

Potential Fishery Impacts Elsewhere: Case Study Georges Bank

Map of Infestation on Georges Banks: 2003

Above: Area of First invasion when discovered in November, 2003, ve tunicate (yellow-shaded polygon) . Map based on NOAA National Ocean Service (NOS) Chart 13200, depths in fathoms. Source USGS Sound Waves Monthly Newsletter Water depth 40 -65 meters, currents 50-100 cm/s 6 square nmiles in 2003

Map of Infestation on Georges Banks: 2004

Above: Area of invasive tunicate (yellow-shaded polygon) surveyed in November 2004. Map based on NOAA National Ocean Service (NOS) Chart 13200, depths in fathoms. Source USGS Sound Waves Monthly Newsletter 40 square nmiles in 2004

Map of Infestation on Georges Banks: 2005

Above: Area of invasive tunicate (yellow-shaded polygon) as of August, 2005. Map based on NOAA National Ocean Service (NOS) Chart 13200, depths in fathoms. Source USGS Woods Hole Website 67 square nmiles in August, 2005 (Valentine et al., 2007)

Implications from Georges Banks Infestation:Groundfish?

Dvex mats barrier to groundfish access to benthic prey underneath. Worms increase in numbers from lowered predation by groundfish. (Valentine et al. 2007) Dvex not a substitute for that prey. Fragments found in groundfish stomachs but provide only 10% of their nutritional value when eaten.

Atlantic Cod

Implications from Georges Banks Infestation:Groundfish?

The acidic tunic could kill any fish eggs or larval fish settling on Didemnum sp. (Osman and Whitlatch 1995a, Cohen 2005, Pederson et al. 2005). Concern that species with juvenile life cycle connection to pebble gravel substrate (Atlantic cod and Haddock) could be negatively affected. (Lengyel et al. 2009).

Haddock

Implications from Georges Banks Infestation:Groundfish?

However, may benefit Winter Flounder Dvex has a positive effect on two species of polycheate worms and a cancer crab. Winter flounder have increased numbers of these as prey where Dvex occurs (Smith 2010). They have small mouths that slurp food like people slurp spaghetti and may be able to penetrate mats.

Winter Flounder

Implications from Georges Banks Infestation:Scallops?

Larval bay scallops avoid settling on Dvex colonies, possibly deterred by the low pH (5.9) of the tunic surface. Widespread colonization of substrata by Dvex could reduce recruitment. Morris et al. (2009) Dredging of scallops may serve to spread Dvex through fragmentation. Lengyel et al. (2009) Overgrowth of scallops may reduce survivability and increase time to shuck (J. Pederson)

Toxic surface may reduce larval settlement. Valentine et al. (2007)

Scallop and Substrate Infested on Georges Banks

Colonies of the tunicate genus Didemnum (probably the species D. vexillum) encrusting pebble gravel habitat and a sea scallop 5 inches in diameter. November 2003. Northern Georges Bank. Water depth 48 m. (157 ft). 41 deg 57.149min N lat, 67 deg 30.891 min W lon. Photo by USGS.

What Are Implications to Alaska? Pacific Herring

Herring Spawn in Sitka Sound Photo: Courtesy Marnie Chapman

Herring Spawn in Dvex infested Whiting Harbor which is a traditional subsistence harvest area.

Herring could avoid spawning on Dvex Dvex could reduce quality of eelgrass and kelp as spawning substrate by overgrowth. Carman and Grunden (2009) Herring eggs that settle on Dvex could die or become impaired from low pH (5.9) or elevated toxins Sewall et al. (2009) found reduced pH depressed the growth and protein synthesis rates of developing Pacific herring embryos and increased mortality to 88% at the lowest pH levels (6.54).

Potential Impacts to Herring

What Are Implications to Alaska? Scallops

Rock scallops attach to rocks. Bay and weathervane scallops prefer sand or gravel ocean bottom from 50-200meters (middle to outer shelf). The only commercial scallop fishery in Alaska is for weathervane scallops on the outer coast from Cape Spence to Yakutat. Rock scallops are being considered a potential native mariculture species for Alaska.

Weathervane Scallop

Potential Impacts to Scallops Dvex could impact all species if growing on gravel, rocks or other hard surfaces by habitat alteration and growing on their shells. Larval settlement could be deterred or larval survival reduced by Dvex infested surfaces due to low pH and toxicity of tunic. Dredging of sea floor with nets to harvest could be a vector for spread

Weathervane Scallop

What Are Implications to Alaska? Pinto Abalone

NMFS Species of Concern since 2002. Occur intertidal to subtidally from 30 to 100m on rocky exposed shorelines in the southern and western portions of Southeast Alaska. Graze on marine algae. Potential mariculture species for Alaska.

Pinto Abalone

Potential Impacts to Abalone Could impact abalone on rocky shorelines where they might overlap. Could impact abalone by growing on marine algae that pinto abalone feed on and by growing on their shells. Deter larval settlement survival due to low pH and toxicity of tunic, Or smothering of the encrusting red algae, Lithothamnion, which releases a chemical that induces larval settlement.

Pinto Abalone

What Are Implications to Alaska? Groundfish – Gulf of Alaska

Complex of over 25 species including walleye pollock, Pacific cod, sole and other flatfish sp., rockfish sp., squid, octopus, etc.

Pregnant rockfish and glass sponge, Photo Pat Malecha, NOAA

What Are Implications to Alaska? Groundfish – Gulf of Alaska

Many adult species occur on the shelf or slope, many associated with pebbly/gravel habitat at similar depths To Georges Banks Juveniles species nearshore? Pacific cod associated with eelgrass in Prince William Sound (Laur and Haldorson 1996, Dean et al. 2000) MULTIPLE IMPACTS POSSIBLE TO MANY SPECIES CLUES TO IMPACTS FROM GEORGES BANKS

Pregnant rockfish and glass sponge, Photo Pat Malecha, NOAA

Where Could Dvex Infest Alaska? PRELIMINARY MAPPING by Allen Butner, Steve Lewis and Linda Shaw of NOAA AKR Used parameters of the Shorezone Coastal Inventory and Mapping Project georeferenced digital imagery of biology and geology of Alaska’s coast INCLUDED: Gravel, Rock and Anthropogenic Hard Surfaces Very Protected, Protected and Semi-Protected Coastal Features

Where Could Dvex Infest Alaska?

EXCLUDED: Sand, Silt and Mud (even where mixed with the hard surfaces listed above) Freshwater Deltas, Rivers and Marshes (prefers salinity above 25 ppt)

Where Could Dvex Infest Alaska?

LIMITATIONS: Does not include temperature (Dvex survives -2°C to 24°C, dormant/die below 9°C ) Some disagreement on wave energy in literature, chose conditions similar to Whiting Harbor (very protected to semi-protected) Proxy of freshwater sources not a direct measure of salinity Assumes Human Vector Transmission – larvae do not disperse far

Original Artwork licensed to NMFS, © Ray Troll 2002, © Terry Pyles, colorization 2002.

Photo/Image Credits: ADF&G, G. Ashton, CSRIO, Robert Chadwick, Gary Freitag, Heather Mueret- Woody, Linda Shaw, Whitney Rapp, en.academic.ru,

trailershut.com,alaskaharvest.com,yukonnews.com,outdoorswebshots.com,myhopemydreamsmylife.blogspot.com, www2.ucsc.edu, divernet.com, pznow.co.uk, dailykos.com, myclassiclyrics.com, gpsinformation.org, simonsanctuary.org,

ehow.com, njscuba.net,winterfoundenhancement.blogspot.com References: Available Upon Request

Thank You: Greg Ruiz and Linda McCann of Smithsonian Environmental Research Center

C. Sarah Cohen, San Francisco State University Tammy Davis, Alaska Department of Fish and Game

Heather Meuret-Woody, Sitka Tribe Marnie Chapman, UAS-Sitka

Gary Freitag, Sea Grant and UAS-Ketchikan Grant Miller, Whiting Harbor Aquafarm

Lynn Wilbur, Sitka Sound Science Center