Download Potential Fishery Impacts to Alaska from a Marine Invasive Species: the Colonial Tunicate Didemnum vexillum

Potential Fishery Impacts to Alaska
from a Marine Invasive Species: the
colonial tunicate Didemnum vexillum
Klas Stolpe Juneau Empire
Linda Shaw, National Marine Fisheries Service
American Fisheries Society, Alaska Chapter
October, 2012
● 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
What is an “Invasive Species”? *
"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
Example: The Alien Monster
Not Native To Earth, i.e. from
Outer Space
+
Threat to Human Health
= Invasive Species
Impacts of 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
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
Photos: Puget Sound
Partnership, Paul Barter,
DVEX IS A PROBLEM
WORLDWIDE
Suffocating
mussels
In New Zealand,
Fouling mariculture
gear in British
Columbia
And Puget Sound
DISCOVERY COINCIDED WITH BREAK UP OF INFESTED DOCK
Photo Source: Marnie Chapman
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.
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
Dvex Strategy: Learn More about the biology
of Dvex In Whting Harbor
Potential for Explosive
Growth
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?
Toxic surface may reduce larval settlement.
Valentine et al. (2007)
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)
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 Dvex infested Whiting Harbor which is a
traditional subsistence harvest area.
Herring Spawn in Sitka Sound Photo: Courtesy Marnie Chapman
Potential Impacts to Herring
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).
What Are Implications to Alaska?
Scallops
Weathervane Scallop
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
What Are Implications to Alaska?
Pinto Abalone
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.
What Are Implications to Alaska?
Groundfish – Gulf of Alaska
Pregnant rockfish and glass sponge,
Photo Pat Malecha, NOAA
Complex of over 25 species including
walleye pollock, Pacific cod, sole and other
flatfish sp., rockfish sp., squid, octopus, etc.
What Are Implications to Alaska?
Groundfish – Gulf of Alaska
Pregnant rockfish and glass sponge,
Photo Pat Malecha, NOAA
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
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
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,myhop
emydreamsmylife.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
Original Artwork licensed to NMFS, © Ray Troll 2002, ©
Terry Pyles, colorization 2002.