windows. Differences in the response of the two species to environmental forcing and possible interactions between the two species, either direct through competition, or indirect through the food web, also became apparent.
Phytoplankton assemblages in a productive Mediterranean coastal wetland: Kalloni solar saltworks, Greece.
Evagelopoulos A1, Spyrakos E2 &
1Department of Marine Sciences, University of the Aegean, 81100, Mytilene, Greece
2Applied Physic Department. 2 Biochemistry, Genetic and Immunology Department, 3Aquatic Ecology,University of Vigo. Spain.
Nutrient rich water from the productive Kalloni Gulf enters Kalloni solar saltworks almost year-round and nutrients are concentrated in the brine, sequestered in the bottom sediment of the ponds or assimilated by phytoplankton, microphytobenthos and macrophytes. The net result has been a continuous accumulation of organic matter in the bottoms of the ponds over the past few years. The aim of this study is to describe the spatial structure and seasonal variations of the phytoplankton assemblages (nano- and microphytoplankton) at the low salinity (<100 psu) ponds of the saltworks and to identify important controlling factors. A combination of phytoplankton descriptors (taxonomic composition, cell density, biomass) and environmental parameters (physical, chemical, biological, meteorological) were measured by means of two seasonal samplings that were carried out at seven sites along the salinity gradient. Phytoplankton assemblages consisted of estuarine and coastal species belonging mostly to Bacillariophyceae, Dinophyceae, Cryptophyceae, Euglenophyceae, Prasinophyceae and Cyanophyceae. The assemblages were found to be spatially heterogeneous and seasonally variable: Blooms of Euglena acusformis and Myrionecta rubra (an autotrophic ciliate) were recorded at the lower salinity ponds in autumn, whereas a bloom of prasinophycean algae was documented at the higher salinity ponds in summer. Phytoplankton is apparently an important component of the primary producers in the study area and its spatial structure and seasonal dynamics are seemingly controlled by factors such as the salinity gradient, the distance from the sea and the considerable but seasonally variable inputs of new nutrients from the sea and nutrients regenerated within the ponds.