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March 19, 2004
An Overview of Algal Toxins and Toxic Activity in Maryland Tidewaters

Maryland Department of Natural Resources, Department of the Environment and Department of Health and Mental Hygiene coordinate monitoring on the presence of algal toxins in tidal waters. Toxins represent a risk to human health but also the health of living resources in the Chesapeake and Coastal Bays. Advances in technology for toxin detection and the science surrounding algal toxins are, however, evolving rapidly. With new analytical techniques, toxins are being discovered in algal species previously considered non-toxic. As analytical techniques improve, algal toxins can be detected, identified and monitored in a more timely and accurate manner.

Monitoring of algae populations in Maryland has been conducted since the early 1980's and identified possibly-toxic species. Microscopy and newly developed genetic probes for monitoring have been the first steps used in assessing potentially toxic algal events. Since the findings on Pfiesteria associated with fish kills and human health effects in 1997 on the lower Eastern Shore of Chesapeake Bay, additional monitoring and surveillance of diverse algal toxins has been conducted. Table 1 lists the algal toxins detected and their concentrations. Table 2 presents additional toxic bioassays results that demonstrate toxic activity, however, the identity and composition of the specific toxins may not be completely known. Possibly-toxic algal species have been identified in Maryland's coastal bays but toxic activity has not been confirmed for any blooms.

Table 1. Algal toxins identified in Maryland tidewaters.
Toxin
Species
Toxin Concentration
Event year
Locations
Reference
Microcystin Microcystis aeruginosa 0.4 g/L -
~1200 g/L		 2000 & 2003 massive blooms, reports of human health effects (skin, eye, irritations, upset stomach) Sassafras R. Potomac R., Chester R. Magothy R. and Bush R. in Chesapeake Bay MD DNR unpublished data
Anatoxin-a Anabaena Low conc
0.009 g/L,
0.11 g/g dry wt		 2002 visual bloom. Poplar Island dredge project, Chesapeake Bay. MD DNR unpublished data
Domoic acid Pseudo-nitzschia seriata 0.08 pg DA-equl/cell to 0.438 pg DA/cell 2002 test sample Choptank River isolates Thessen et al 2003 abstract
Okadaic acid Dinophysis acuminata Present but below FDA standards for food 2002 bloom detected in water sample Potomac River Tango et al. 2002
Saxitoxin Cyanophytes 0.003 µg/L 0.009 µg/g dry wt 2003 - massive algal bloom Sassafras R. MD DNR unpublished data

Table 2. Toxic algal activity for species where only portions of the chemical composition and structure are known.
Toxic Activity
Species
Notes
Event year
Locations
Reference
Toxic shellfish larval bioassay Prorocentrum minimum Shellfish toxicity in the laboratory 1998 & 2000 blooms Choptank River isolates, Aquaculture events Hegaret and Wikfors 2004a,b,Tango et al. 2004
Cytotoxic, hemotoxic, ichthyotoxic bioassays Karlodinium micrum Karlotoxins KmTox1-6, 1996, 2002 & 2003 fish kill sites Multiple locations, HyRock farms, plus several fish kill sites Deeds et al, 2002, Goshorn et al. 2002, MD DNR and MDE 2003 unpublished data
Toxic fish bioassay    Pfiesteria piscicida    Positive toxic bioassays.Links with human health effects (Grattan et al. 1998).     1993 fish kill site Jenkins Crk, Choptank River in Chesapeake Bay, sediment sample Lewitus et al 1995
1991 analysis of samples from 1987 Indian River fish kill. Delaware inland Bays Burkholder et al. 1995
1994 Patuxent River in Chesapeake Bay Burkholder et al. 1995
1997 fish kill and human health events Pocomoke River, Chicamacomico R. MD DNR 1998 reportMagnien 2001 a,b, Burkholder and Glasgow 2001.

References

    Burkholder, J.M. and H.B. Glasgow. 2001. History of toxic Pfiesteria in North Carolina estuaries from 1991 to the present. BioScience 51 (10): 827-841.

    Burkholder, J.M., H.B. Glasgow Jr. and C.W. Hobbs. 1995. Fish kills linked to a toxic ambush-predator dinoflagellate: distribution and environmental conditions. Mar. Ecol. Prog. Series 124:43-61.

    Deeds, J.R., D.E. Terlizzi, J.E. Adolf, D.K. Stoecker and A.R. Place. 2002. Toxic activity from cultures of Karlodinium micrum (=Gyrodinium galatheanum) (Dinophyceae) a dinoflagellate associated with fish mortalities in an estuarine aquaculture facility. Harmful Algae 16:1-21.

    Goshorn, D., J. Deeds, P. Tango, A. Place, M. McGinty, W. Butler, R. Magnien. 2002. (in press). occurrence of Karlodinium micrum and its association with fish kills in Maryland estuaries. in K. Steidinger (ed) Proceedings of the Xth International Harmful Algae, St. Petersburg, FL.

    Grattan, L. M., D. Oldach, T.M. Perl, M.H. Lowitt, D.L. Matuszak, C. Dickson, C. Parrott, R.C. Shoemaker, C. L. Kauffman, M.P. Wasserman, J.R. Hebel, P. Charache and J. G. Morris, Jr. 1998. Learning and memory difficulties after environmental exposure to waterways containing toxin producting Pfiesteria or Pfiesteria-like dinoflagellates. Lancet. 352:532-539.

    Hegaret, H. and Wikfors. G. 2004a. Time-dependent changes in hemocytes of Eastern oysters, Crassostrea virginica, and northern bay scallops, Agropectens irradians irradians, exposed to a cultured strain of Prorocentrum minimum. Harmful Algae (in review).

    Hegaret, H. and Wikfors. G. 2004b. Effects of natural and field-simulated blooms of the dinoflagellate Prorocentrum minimum upon hemocytes of Eastern oysters, Crassostrea virginica, from two different populations. Harmful Algae (in review).

    Lewitus, A., J. Hawkins, M. Dykstra, E. Noga, D. Moye, and R. Cone. 1995. Discovery of the "Phantom" dinoflagellate in Chesapeake Bay. Estuaries. 18:373-378.

    Magnien, R.E. 2001a. State monitoring activities related to Pfiesteria-like organisms. Env. Health. Persp. 109(suppl 5):711-714.

    Magnien, R.E. 2001b. The dynamics of science, perception and policy during the outbreak of Pfiesteria in Chesapeake Bay. BioScience 51:843-852.

    Maryland Department of Natural Resources.1998. Water quality, habitat and biological conditions of river systems affected by Pfiesteria or Pfiesteria-like organisms on the Lower Eastern Shore of Maryland:1997 Summary. 34 pp plus figures.

    Tango, P.J., W. Butler, R. Lacouture, R. Eskin, B. Michael, R. Magnien, D. Goshorn, W. Beatty, K. Brohawn, R. Wittman and S. Hall. (In press). An unprecedented bloom of Dinophysis acuminata in Chesapeake Bay. in K. Steidinger (ed) Proceedings of the Xth International Harmful Algae, St. Petersburg, FL.

    Tango, P.J., Magnien, R., Butler, W., Lacouture, R., Luckenbach, M., Poukish, C., and Luckett, C. 2004. (In review). Characterization of Impacts and Potential Effects of Prorocentrum minimum blooms in Chesapeake Bay. Harmful Algae.

    Thessen, A., D.K. Stoecker, P. Tango, S. Morton and D. Caron. 2003. Abstract. The presence of domoic acid in Pseudo-nitzschia from the Choptank River, A Chesapeake Bay tributary. Second Symposium on Harmful Marine Algae in the United States, Dec. 9-13, 2003, Woods Hole Oceanographic Institute, Woods Hole, MA.

    Unpublished data from Peter Tango, Maryland DNR.