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

2012 Microcystin Results

2012 Tissue Microcystin Concentrations

Literature observed physiological impairments

Estimated Daily Intake

Scenario: 60 kg person, consuming 75 g serving of tissue (Garcia et al 2010)

Water Column MC vs. Tissue MC

Interspecific Microcystin accumulation

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

Questions ?