Assessment of harmful algae bloom species in the Maryland Coastal Bays

Thirteen potentially harmful algae taxa have been identified in the Maryland Coastal Bays: Aureococcus anophagefferens (brown tide), Pfiesteria piscicida and P. shumwayae, Chattonella spp., Heterosigma akashiwo, Fibrocapsa japonica, Prorocentrum minimum, Dinophysis spp., Amphidinium spp., Pseudo-nitzchia spp., Karlodinium micrum, and two macroalgae genera (Gracilaria and Chaetomorpha). The greatest number of species occurred in the polluted tributaries of the St. Martin River and Newport Bay. Approximately five percent of the phytoplankton species identified in the Maryland Coastal Bays represent potentially harmful algal bloom (HAB) species. The HABs are recognized for their potentially toxic properties and, in some cases, their ability to produce large blooms capable of negatively affecting light and dissolved oxygen resources. Brown tide (A. anophagefferens) has been the most widespread and prolific HAB species in the area in recent years, producing growth impacts to juvenile clams in test studies and potential impacts to seagrass distribution and growth (see Chapter 7.1). Macroalgal fluctuations may be evidence of a system balancing on the edge of a eutrophic (nutrient-enriched) state. No evidence of toxic activity has been detected among the Coastal Bays phytoplankton. However, species such as Pseudo-nitzschia seriata, Prorocentrum minimum, Pfiesteria piscicida, Dinophysis acuminata and Karlodinium micrum have produced positive toxic bioassays or generated detectable toxins in Chesapeake Bay. Pfiesteria piscicida was retrospectively considered as the likely causative organism in causing a large historical fish kill on the Indian River, Delaware. Similarly Chattonella cf. verruculosa was implicated in a large fish kill and persistent brevetoxins detected in Delaware’s Rehoboth Bay during 2000. Tracking potential HAB species diversity, abundance, distribution and toxic activity through time provides important indicators of environmental change within the Coastal Bays. Maryland’s Coastal Bays: Ecosystem Health Assessment Chapter 7.2