Survey of Small Coccoid Eukaryotic Algae in Open Oceans

Bigelow Laboratory For Ocean Sciences, East Boothbay ME

Investigators

Abstract

The open oceans cover 66% of the earth's surface, and the primary producers are primarily tiny coccoid organisms that are very abundant. At any one instant in time, these cells are so numerous that if they were arranged as a packed mass in the shape of a standard 1 x 12 board, this plank would stretch from the earth to the moon. Furthermore, these cells divide approximately once per day, thereby producing a new plank each day. Unlike forests, where dividing cells accumulate in the tree for 100 or more years, these tiny plants of the ocean are quickly eaten. That is, the phytoplankters directly or indirectly feed the fishes, shrimp, whales, etc., so that this amazing "plank to the moon" is produced and eaten daily. Consequently, the ocean waters appear transparent and no forest-like biomass accumulates. Of these tiny organisms, the eukaryotic algae are an important component. However, they have a very simple morphology and are nearly impossible to identify using either light or electron microscopy. Although very similar in appearance (little spherical cells), from DNA studies it is obvious that these organisms represent several very different evolutionary groups. It has only recently become apparent that molecular studies involving gene sequence analysis are needed to understand this biodiversity. Culture collections, especially the Provasoli-Guillard National Center for Culture of Marine Phytoplankton (CCMP) at the Bigelow Laboratory, hold numerous strains of unidentified tiny coccoid oceanic algae from the blue water regions of the Atlantic, Pacific and Indian Oceans. In this study by Dr. Robert Andersen, these cultures and additional samples will be examined to assess oceanic biodiversity. The proposed research will utilize nuclear ribosomal gene sequences to identify and classify these diverse organisms. Cryptic species complexes will be studied using additional gene sequences (for example, genes of photosynthetic enzymes). The species composition in different oceans, as well as for different regions of the same ocean, will be compared. At present, it is unknown whether the Atlantic, Pacific and Indian Oceans have similar or different species of these abundant tiny eukaryotic coccoid algae. The results of this study will contribute to our knowledge of ocean ecosystems and their productivity. Furthermore, preliminary studies have shown that some of these tiny algae produce compounds that are beneficial for human health. For example, the newly discovered oceanic pinguiophytes produce huge amounts of polyunsaturated fatty acids, which from medical research is known to reduce heart disease.