aers fall 2012
TRANSCRIPT
Phytoplankton consumption and Microcystin accumulation by fishes of the Tidal Fresh
James RiverJoe Wood and Paul Bukaveckas, VCU
Outline
• Background on the James River CHLa Study• What is Microcystin?• Research Questions• Methods & Results• Conclusions & Questions
James River CHLa Study• EPA takes over CB
clean up, mandates quantitative CHLa standards to reduce nutrient loads
• DEQ requests 3 years to ensure CHLa standards are scientifically defensible
The Tidal Fresh James is extremely productive
relative to other regions of the Chesapeake Bay
Study Site
This high productivity occurs due to release from light limitation and assimilation of large anthropogenic
nutrient loads
156 (Richmond)
0 (Chesapeake Bay)
Bukaveckas et al 2011, Estuaries and Coasts
Km 169: Deep& Narrow
Km 118: Wide & Shallow
Impairments associated with Eutrophication in the Upper James
Hypoxia, Dead zones not a concern in this system
What is Microcystin?• Secondary
Metabolite produced by several bloom forming- cyanobacteria
• Increased Probability of Detection in Eutrophic Systems
Cyanobacteria
Contains Microcystin
producing gene
Gene Active Gene Inactive
Lacks Microcystin producing gene
Poste et al 2011
Toxicity
Impacts of Microcystin on Biota
Muscle Loss, increased
abnormalities, reduced fertility
in Threadfin Shad (Acuna et
al 2012)
Increased Apoptic Cell
death, Tumors and Liver
Cancer in Trout (Fischer et al
2011)
Mortality, Liver Hemorrhaging
and tumor formation in Sea Otters, (Miller et al
2010)
Mortality and Hematological
Lesions in Flamingos
(Miller et al 2010)
WHO Drinking Water Standard
Microcystin in the James
2011Research Questions1. What fish consume phytoplankton in this system?2. Is Microcystin assimilated by Fish in the Tidal Fresh James
River?3. What factors increase vulnerability to toxin exposure?
Methods
• Fish collection & Species Background• Gut Contents analysis• Microcystin Extraction techniques
Specimen Collection• 75 Fish sampled via Electroshocking monthly
(May-October 2012) Benthic feeders:• Blue Catfish (0-20 cm)• Blue Catfish (20-40 cm)• Adult Gizzard Shad
Pelagic Feeders: • YOY Gizzard Shad• Threadfin Shad• Atlantic Menhaden
Threadfin Shad
Gizzard Shad
Atlantic Menhaden
Blue Catfish
YOY Gizzard
Gut Content Analysis• Fish digestive tracts emptied, weighed and
analyzed for CHLa, POC & PON
• CHLa extracted with 90% acetone and measured with a TD-700 Fluorometer• C&N measured
on a Perkin-Elmer CHN analyzer.
Microcystin Extractions• Livers and Muscle dried, ground with a mortar and pestle.• Material was extracted in 75% Methanol, centrifuged and
supernatant sampled. (Wilson et al 2008, Garcia et al 2010)• Supernatant is then diluted to < 5% Methanol• Samples processed with Abraxix© ELISA Microcystin Kit • Recovery efficiency was estimated at (80%-Muscle,75% Liver) which is
comparable to literature values 50-114%. All blanks returned 0.
Results: Fish Diet
Summary
Diet Quality (CHLa)
CHLa per Fish
CHLa per fish, normalized to fish size
Pelagic Filter feeding Fish consume higher concentrations of CHLa, and more CHLa when normalized for fish size
Conclusions
• Pelagic Consumers diet contains a higher proportion of CHLA, these fish consume more CHLa per g Fish
• Microcystin accumulates in liver and muscle tissues at levels that may cause impairment
• Pelagic feeding fish may be more vulnerable to Microcystin exposure
Future Work
• Do algiviorous fish have any role as top down control on phytoplankton? Do they Exacerbate Algal blooms?
• How far does Microcystin move up the food web? Piscivorous Birds?
• What are the physiological impairments associated with this level of Toxin accumulation?
• How far does this toxin spread geographically?
Acknowledgements• Mac Lee• Ryan Weaver• Aaron Porter• Dave Hopler • Chuck Fredrickson• Jamie Brunkow• Geoff Austin• James River Association• DEQ• City of Richmond• VCU Rice Center