HPLC Photopigment Analysis as a Measure of Phytoplankton Community Composition
in Long Island Sound

Yaqin Li 1, Christine B. Olsen 1, Matt Lyman 1, Paul Stacey 1, Laurie Van Heukelem 2
and Senjie Lin 3

1 Connecticut Department of Environmental Protection, Hartford, Connecticut
2 Horn Point Laboratory, University of Maryland, Cambridge, Maryland
3 Unversity of Connecticut Avery Point, Avery Point, Connecticut

The Connecticut Department of Environmental Protection started high-performance liquid chromatography (HPLC) photopigment monitoring in 2002 with the funding from US EPA National Coastal Assessment Program. Seventeen stations throughout Long Island Sound were sampled monthly for photopigments in addition to other water quality parameters such as nutrients, oxygen, temperature, salinity and phytoplankton and zooplankton species and abundance.

Phytoplankton is an important component of marine ecosystems and understanding of phytoplankton dynamics is essential to developing effective hypoxia management programs for Long Island Sound. Microscopic examination is the typical method for phytoplankton identification and enumeration. However, the microscopic method is very labor intensive and requires high level of taxonomic skills thus it is practically difficult for a monitoring program covering large temporal and spatial scales. In addition, small phytoplankton and those hard to perverse species are often unidentifiable or missed by microscopic method. Alternately, phytoplankton groups can be characterized based on their pigment composition.

Total of 26 pigments including various chlorophylls and carotenoids were separated and quantified by HPLC. A preliminary analysis by using software CHEMTAX based on these pigments revealed that there were considerable amount of small flagellates in the family Cryptophyceae, Prasinophyceae and Haptophyceae in summer in addition to diatoms and dinoflagellates. The concurrent microscopic identification of phytoplankton indicated a large amount of small unidentifiable cells in the sample in addition to diatoms and dinoflagllates. The spatial and temporal dynamic of phytoplankton in Long Island Sound, and its role in hypoxia management, will be discussed as analyses continue.

Keywords: HPLC photopigments, phytoplankton composition, water quality, Long Island Sound