One of our daily journeys across Flanders Bay nine years ago revealed a concentration of a red algae suspended near the surface of the estuary waters, so dense and wide-spread as to produce a visual effect of bands of reddish-colored water, distinctly patterning the surface of the bay from our distance perspective to a closer view under the pontoons of our tour boat as it sped along cutting across the bands in our path. We took a sample and brought it to Long Island Aquarium’s senior aquarist, Todd Gardner, for identification. Under the microscope, what appeared was a spiral chain of four cells with a flagellum. It was the dinoflagellate Cochlodinium polykrikoides, known in blooms around the world as Red Tide. Fortunately, this is not the same red alga organism that produces a neurotoxin that can kill large mammals through ingestion or aspiration. However, we learned subsequently through the work of Stony Brook SoMAS Professor, Dr. Chris Gobler, that blooms of C. polykrikoides have impacted NY waters with very disturbing outcomes of “complete mortality of captive finfish … as well as caged and wild shellfish.” (Gobler, C., “The cause, effects, dynamics, and distribution of Cochlodinium polykrikoides blooms and cells in the Peconic Estuary, Suffolk County, NY”, p.2)
Furthermore, this red tide appears toxic to other phytoplankton and zooplankton, as well as the different life stages of many fish, hard clams, oysters and bay scallops, and is able to grow rapidly in varied nutrient conditions. In 2008 and 2009, local fishermen and aquaculturists reported losses of harvest during red tide blooms; closer examination of effected species, exposed to concentrations of Cochlodinium, revealed loss of gill function directly related to the density of the algae.
As our tour boat season closes this October 2013, we have once again experienced red tide in Flanders Bay and recognize it now as an annual event that challenges the local fishing industry, perhaps with as grave repercussions on the productivity of these waters as felt with earlier assaults of brown tide (Aureococcus anophagefferens) in the Peconic Estuary and other bay systems surrounding Long Island. Although thought to be rare prior to this century, Cochlodinium blooms now occur annually and globally in estuaries that provide nursery habitat, food energy, and shelter for 70% of marine life that humans harvest from Earth’s one great Ocean.
Submitted by Ann Haskell, Blue Ocean Institute marine educator