STATUS OF AQUATIC NON-INDIGENOUS SPECIES IN THE DULUTH-SUPERIOR HARBOR Anett Trebitz, Greg Peterson, Joel Hoffman, John R. Kelly, Corlis West U.S. Environmental Protection Agency, Mid Continent Ecology Division, Duluth MN MN WI Invasive Species Conference St. Paul MN, Nov. 2010. UNITED STATES ENVIRONMENTAL AGENCY PROTECTION
Goal: Develop a generalized approach to early detection monitoring for aquatic non-indigenous species (NIS) in vulnerable coastal ecosystems Technical Challenge: Finding rare before it becomes common, doing so efficiently without knowing what to look for (not targeting particular species or pathways) Objectives of This Presentation: - Report on NIS found - Describe their abundance & distribution - Examine habitats and sampling gears they occurred in - Discuss challenges in determining invasion status
Duluth-Superior Harbor (St. Louis R. Estuary) as case study GL s largest shipping port, known invasion hotspot Large, open, ecotone system with substantial habitat diversity and range in anthropogenic impacts. Introduction Vectors Shipping - ballast water, tank-residue, cargo hitchhikers Recr. boating & fishing - bilge, bait-bucket, hull & trailer fouling Population center - sewer, aquarium dumping, transport. nexus
Data collection approach Extensive sampling to amass data with which to evaluate alternative strategies. Two designs for covering space: random, targeted.
Data types and sources (sampling in 2005, 2006, 2007) electrofishing Fish 239 separate samples bottom trawl sweep net (vegetation) fyke net benthic sled beach seine Benthos 207 separate samples colonization plates (littoral) ponar Habitat (fish & benthos stations) depth, vegetation, substrate water quality geospatial context
19 benthic NIS detected - 8% of total taxa quagga mussel* Lumholtz waterflea* Henslow s pea clam* hump-backed pea clam* 2 oligochaete worms** Ischium sideswimmer New Zealand mud snail newly detected *new to L. Sup. ** new to G. Lks. zebra mussel most abundant benthos NIS a colonial hydrozoan Asian clam 3 oligochaete worms zebra mussel European valve snail Moitessier s pea clam tiger sideswimmer greater European pea clam fasciatus sideswimmer detected in 10 yrs prior to our study present >10 yrs Joint press releases by U.S. EPA, Sea Grant, U.S. FWS, MN-DNR, WI-DNR
Example distributions for benthic NIS USGS adult size ~2.5 cm USGS adult size up to 5 cm Zebra mussel Native to Eurasia. First detected 1989. Very abundant in lower & middle system. Asian Clam Native to Asia first detected ~1999 Restricted, but abundant in unique environment. USACE widespread, extremely abundant spatially restricted, but abundant in unique habitat common although not abundant adult size 8-11 mm Ischium sideswimmer Native to Eurasia. First detected 2005. Scattered throughout system.
10 fish NIS detected 24% of total taxa round goby & eurasian ruffe most abundant fish NIS tubenose goby round goby 3-spine stickleback brook silverside white perch Eurasian ruffe freshwater drum rainbow smelt common carp alewife present <10 yrs present 10-20 yrs present >50 yrs We did not catch any NIS salmonids, which are seasonal users of DSH
Example distributions for fish NIS U.S. EPA adult size: 3.5 to 6.5 cm (max 8 cm) adult size 10 to 15 cm (max 23 cm) Threespine stickleback Native to east and west coasts of N. America including Lake Ontario. First detected 1994. Relatively rare. Eurasian ruffe Native to Eurasia. First detected 1986. Abundant throughout system. localized, not abundant widespread, very abundant widespread, moderately abundant adult Size: 12 to 20 cm (max 26 cm) White perch Native to Atlantic slope. First detected 1986. Abundant throughout system.
Varied Places of Origin & Modes of Arrival Eurasia 2 dreissenid mussels 4 peaclams 1 amphipod 3 oligochaetes colonial hydrozoa European valve snail -- common carp 2 gobies eurasian ruffe Africa/Pacific Rim Lumholtz waterflea N. Zealand mudsnail Asian clam N. America 2 oligochaetes 2 amphipods -- brook silverside freshwater drum alewife rainbow smelt threespine stickleback white perch carp? 2 d Deliberate Introduction Unintentional direct delivery (shipping implicated) Natural dispersal (range expansion, barriers removed)
Taxonomy & Historic Records as Challenge Benthic surveys often not to best attainable taxonomic resolution (expensive, unnec. for biotic assessment). Can render otherwise thorough surveys uninformative w.r.t. NIS. Ex: Extensive 1995 EMAP-type survey of DSH reported NO benthic NIS, but had IDs only to genus and only to class for oligochaetes. Lack of historic records makes arrival date and even NIS status of some taxa unclear. Ex: historic range of oligochaetes poorly documented; unclear if first finding of circumboreal species is range expansion or not.
Gear/habitat differs by NIS - benthos bottom samples (ponars, benthic sled) littoral samples (sweep net, coln z. plates) 4 oligochaetes 4 peaclams Asian clam NZ mudsnail valve snail 2 dreissenids 1 oligochaete 3 amphipods NIS gear/habitat pattern doesn t necessarily match related native taxa; unwise to assume you know where to look. * single instance of D. lumholtzi & colonial hydrozoa not enough to establish pattern
Gear/habitat differs by NIS - fish Newest Eurasian invader, tubenose goby, is not vulnerable to the gear (trawls) that formed backbone of ruffe invasion monitoring. beach seine (shoreline, very shallow) 3spine stickleback brook silverside tubenose goby round goby eurasian ruffe common carp trawling (open water, deepest) freshwater drum rainbow smelt white perch electrofishing, fyke nets (interm. depth)
Increasing rel. abundance Invasion status varies among NIS Invasion stage framework of Colautti & MacIsaac (2004) Benthos 100 10 1 0.1 0.01 local dom. oligo oligo NZmudsnail valvesnail juv. Dreissena zebra m. oligo E.ischnus Corbicula P.henslow. G.fasciatus oligo oligo P.moitess G.tigrinusquagga m. oligo widespread local rare hydrozoa, peaclam, daphnia rare 0.001 0 20 40 60 80 100 Increasing % occurrence widespread dom. Fish 100 80 60 40 20 0 local dom. silverside alewife drum carp smelt 3sp.stickleback local rare wh.perch tuben.goby ruffe round goby widespread dom. widespread rare 0 20 40 60 80 100 - Some life histories more likely problematic than others, but also depends on habitat match, competition/predation, etc. - We don t yet know path a given NIS will take when it is newly arrived - Ideally we want detection at the localized, rare stage
Percent occurrence (best gear) Invasion status only weakly related to time 80 Fish r.goby ruffe 100 Benthos zebra m. 60 t.n.goby 80 G.fasciatus 40 20 0 silverside wh.perch 3sp stickleback drum alewife smelt carp 0 20 40 60 80 120 Years since earliest record (back from 2006) 60 40 20 0 E.ischnus P.henslowanum quagga m. NZ mudsnail oligo valve snail oligo peaclam oligo oligo Corbicula hydrozoa oligo daphnia P.Moitess. G.tigrinus EU peaclam 0 5 10 15 20 25 - Whether a NIS expands over time is highly variable. - NIS not necessarily rare when first detected. - Benchmark for monitoring effectiveness should be finding rare species.
Taxa accumulated It takes substantial effort to find some species Probability of detection (%) Widely-distributed species are detected quickly...... rare species take many samples to detect (reliably) Effort = cost, and can mean both in the field and in the lab (taxonomy) 150 100 zebra mussel, pygmy peaclam 100 72 % 86 % 100 % 50 new zealand mud snail 3 peaclams an amphipod european valve snail 1 oligochaete 50 1 amphipod lumholtz waterflea asian clam 0 0 20 40 60 80 Number of samples taken 0 0 20 40 60 Number of samples taken Benthos - 2006 ponars
Impression of invasion depends where you look Fish Exotic richness 0 1 2 3 5 less riverine more riverine - More NIS in lower system Disturbance? Vector proximity? Hydro. gradient? - 2005 gave different impression than 2006 Oligochaetes P. moldaviensis P. vejdovskyi both
Richness % NIS by number Impression of invasion depends on endpoint and gear used Richness % NIS by number Benthos Fish 150 100 50 native NIS 6-9% NIS 35 25 15 native NIS 25-29% NIS 0 5 90 60 Dreissena other NIS 50 30 other NIS ruffe tubenose goby round goby 30 10 0 ponar bottom sled sweep net coloniz. plates electrofish fyke nets seine bottom trawl - Richness: % NIS similar among gear despite total richness differences. - Abundance: dramatic differences in % NIS by gear
Impression of invasion depends on impact on native species
Summary Duluth-Superior Harbor remains invasion hotspot - 19 benthos NIS, 10 fish NIS, 8 new detection records - Plethora of NIS from Eurasia implicates shipping as vector - Degree of invasion varies widely among NIS A complete & nuanced picture takes a thorough and multi-faceted sampling strategy - Sufficient effort to reliably detect rare species - Sufficient taxonomic resolution and thoroughness - Sampling design that enforces spatial coverage - Covering multiple habitats with multiple gear types - Examining multiple endpoints (e.g., richness & abundance) - Status of natives gives context (so sample those too) Work informs ongoing & planned efforts by partners
More Info Kelly et al. Early detection monitoring for vulnerable Great Lakes coastal ecosystems. TOMORROW 11:30. Trebitz et al., 2010, Status of non-indigenous benthic invertebrates in the Duluth-Superior Harbor and the role of sampling methods in their detection. JGLR, in press. Trebitz et al., 2009. Exploiting habitat and gear patterns for efficient detection of rare and non-native benthos and fish in Great Lakes coastal ecosystems. Aq. Inv. 4:651-67. Grigorovitch et al., 2008. The quagga mussel invades the Lake Superior basin. JGLR 34: 342-350. UNITED STATES ENVIRONMENTAL AGENCY PROTECTION Acknowledgements Trawling - Gary Czypinski and crew (U.S. FWS) Field work - Charlie Butterworth, Tim Corry, Brian Sederberg, Jon Van Alstine, Sam Miller, Mario Picinich. Sampling design - Tony Olson (U.S. EPA - Corvallis) GIS - Jesse Adams, Roger Meyer, Tatiana Nawrocki, Matt Starry (CSC Corp). Invertebrate sample processing - Wilson Env. Lab Taxonomy Mary Balcer, Kurt Schmude (UW-Superior), Gerry Mackie (U. Guelph), Brett Nagle (U. Minn.), Igor Grigorovich, John Sandberg, Kevin Stroom (Wilson) Genetic analyses - John Darling (U.S. EPA - Cincinnati)