Phytoplankton composition

The composition of the phytoplankton can firstly be described by the different size fractions. 

The < 3 µm phytoplankton

As it was evidenced in most water masses, 

The taxonomic composition of phytoplankton is still poorly known. The picophytoplankton (was mainly composed of Synechococcus whereas Prochlorococcus constituted only 5% of this size class (Charpy and Blanchot 1998).

The >= 3 µm phytoplankton

Very few data are available on the composition of phytoplankton of size higher than 3 µm. The taxonomic composition of the nano and the microphytoplankton of Takapoto atoll lagoon (table) given by Sournia and Ricard (1976) reveals a predominance of three major groups (diatoms, dinoflagellates and coccolithophorids). The diatoms were the most diversified group whereas the dinoflagellates were the most abundant. 

Twenty years later, observations made in the same atoll by Loret (1999); Sakka (2000); Loret et al (2000) and Sakka et al (2000) show a drastic change in the phytoplankton composition. Indeed, mostly pico and nanophytoplankton were observed, the latter being small phytoflagellates (table). The HPLC pigment analysis outlined the predominance, in term of chlorophyll a, of picocyanobacteria and prymnesiophytes whereas chlorophytes, diatoms and cryptophytes were the secondary groups. The dinoflagellates were mostly heterotrophic as their specific pigment, the peridinin, was not detected by the HPLC method.  

Obviously, investigation methods changed between 1976 and 1996. However, 

This page was based on :

Charpy L, Blanchot J (1998) Photosynthetic picoplankton in French Polynesian atoll lagoons: estimation of taxa contribution to biomass and production by flow cytometry. Marine Ecology-Progress Series 162: 57-70

Delesalle B, Sakka A, Legendre L, Pages J, Charpy L, Loret P (2001) The phytoplankton of Takapoto Atoll (Tuamotu Archipelago, French Polynesia): time and space variability of biomass, primary production and composition over 24 years. Aquatic Living Resources 14: 175-182

References

L Charpy (1996) Phytoplankton biomass and production in two Tuamotu atoll lagoons ( French Polynesia ). Mar. Ecol. Prog. Ser. 145 (1996), pp. 133_¯142

L Charpy and J. Blanchot (1998) Photosynthetic picoplankton in French Polynesian atoll lagoons: estimation of taxa contribution to biomass and production by flow cytometry. Mar. Ecol. Prog. Ser. 162 (1998), pp. 57_¯70.

P. Loret (1999) Le régime alimentaire et la sélection des particules chez l'huître perlière Pinctada margaritifera dans le lagon de Takapoto (Tuamotu, Polynésie française). Thèse de doctorat. , Université de Polynésie française, Papeete (1999).

P. Loret, A. Pastoureaud, C. Bacher and B. Delesalle (2000) Phytoplankton composition and selective feeding of the pearl oyster Pinctada margaritifera in the Takapoto lagoon ( Tuamotu Archipelago , French Polynesia ): in situ study using optical microscopy and HPLC pigment analysis. Mar. Ecol. Prog. Ser. 199 (2000), pp. 55_¯67.

A. Sakka (1999), Structure et dynamique de la communauté planctonique dans le lagon de l'atoll de Takapoto (Archipel des Tuamotu, Polynésie française). Thèse de doctorat. , Université Laval, Québec (1999).

A Sakka, L. Legendre, M. Gosselin and B. Delesalle (2000) Structure of the oligotrophic planktonic food web under low grazing of heterotrophic bacteria: Takapoto atoll, French Polynesia . Mar. Ecol. Prog. Ser. 197 (2000), pp. 1_¯17.

A. Sournia and M. Ricard (1976) Données sur l'hydrobiologie et la productivité du lagon d'un atoll fermé (Takapoto, îles Tuamotu). Vie Milieu 26 (1976), pp. 243_¯279.