Aureococcus anophagefferens clone 1984


Photo: Thin-section TEM by Roger Anderson, Columbia University

Aureococcus anophagefferens  is a 2-3 um spherical, non-motile pelagophyte which has caused destructive ‘brown tide’ blooms in northeast and mid-Atlantic US estuaries for two decades. The first Aureococcus blooms occurred simultaneously in the summer of 1985 in several estuaries in the northeastern US, including Narragansett Bay, Rhode Island, Great South Bay and the Peconic Estuary on Long Island, NY, and putatively in Barnegat Bay, NJ.  Blooms returned to Long Island bays in 1986-88 and have since occurred sporadically in these waters. In recent years, blooms have expanded south along the US east coast into bays in New Jersey, Delaware, Maryland and Virginia.  Aureococcus blooms have also recently occurred in Saldanha Bay, South Africa.  Low abundances of Aureococcus cells have been observed along the entire eastern seaboard of the US from Maine to Florida, indicating the potential for these blooms to continue to spread north and south of their current range.

During initial Aureococcus blooms in eastern and southern Long Island bays, high cell concentrations substantially increased light attenuation, which caused a large-scale die-off of seagrass beds of Zostera marina, a critical habitat for scallops, larval fish, and other species. The bloom caused mass mortality and recruitment failure in populations of Argopecten irradians, which resulted in the collapse of the multi-million dollar bay scallop industry in eastern Long Island. The Aureococcus blooms also appear to have negatively impacted populations of clams (Mercenaria mercenaria) in Great South Bay, which was formerly the largest clam fishery in the state of New York. Subsequent research has established that Aureococcus adversely impacts the growth and survival of many algal grazers, including juvenile and adult hard clams (M. mercenaria), larval and adult bay scallops (A. irradians), adult blue mussels (Mytilus edulis), and micro- and mesozooplankton. Although a toxin has never been isolated from Aureococcus, there is evidence for toxic activity, most likely within the extracellular polysaccharide (EPS) sheath surrounding the cells. This putative toxin deters feeding in bivalves by causing the cessation of cilia movement.

A coastal microalgae species, A. anophagefferens is capable of growing to extremely high densities (> 10E9 cells L-1) and can enzymatically degrade complex forms of dissolved organic matter as a source of cellular carbon and nitrogen.  This species is also known to be well adapted to low light, is associated with annually elevated water temperatures, can rapidly reduce trace metals, and sequesters substantial amounts of carbon during bloom events.   

The Aureococcus genome will be the first sequenced for any Harmful Algal Bloom (HAB) species.   HABs are blooms of phytoplankton cells resulting in conditions that are unhealthy for humans, animals or ecosystems causing by decrease in light attenuation or oxygen levels, or by production of toxins.  HABs may cause marine life poisoning and/or death.  Through analysis of the Aureococcus genome, we hope to glean information regarding mechanisms involved in HAB bloom formation and cessation.

Strain: CCMP1984 isolated from Great South Bay, Long Island, New York.

Publication: Niche of harmful alga Aureococcus anophagefferens revealed through ecogenomics.. Proc Natl Acad Sci U S A. 2011 Feb 23.