PHYTOPLANKTON BIOMASS CONTRIBUTION IN A PAMPEAN POND

CANO MG,; CASCO MA,; SOLARI, L. C.; MACDONAGH, M. E.; CLAPS, M. C.

Joao Pessoa, Brasil

Simposio; Plankton Symposium IV; 2007

Association for Plankton Research

Generally, algal biomass assessments in wetlands include the phytoplankton community not considering the contribution of the rest of the algal associations to the total algal production. This prevents making a complete evaluation of the former community as part of the system. In the present work, biomass contributions (chlorophyll expressed per m2 of pond) of phytoplankton, epiphyton on submerged and emergent macrophytes and epipelon were measured in arheic Lacombe pond with the purpose of, (1) establishing the relative importance of the phytoplankton, (2) evaluate this contribution in the context of the Goldsborough and Robinson´s conceptual model. Sampling was carried out monthly along a year in representative sites with different conditions according to depth and type of macrophytes. Physico-chemical analyses of water were performed following standard methods. Plankton was collected making a five level profile in deeper stations and in the shallow one, subsuperficially samples were taken. Corers of sediment were collected for epipelon sampling and segments of plants were cut at different levels, obtaining the epiphytes by scrapping. Pigment extraction was performed using acetone and calculations were made with Lorenzen´s equation. According to G. & R. model, a lake state developed during the first three months phytoplankton maxima: 150 mg chl. a.m-2). Later, due to submerged macrophytes growth, an open state was observed characterized by epiphyton maxima and  ower levels of phytoplankton biomass. Epipelon biomass varied between 50 and 252 mg chl. a.m-2, recording a considerable contribution from the phytoplanktonic community above.