Sevim Polat

Abundance and biomass of picoplanktonic Synechococcus (Cyanobacteria) in a coastal ecosystem of the northeastern Mediterranean, the Bay of İskenderun

Abstract Changes in abundance and biomass of Synechococcus were studied during five cruises carried out between November 2004 and September 2005 in the İskenderun Bay, northeastern Mediterranean. In addition, spatial and temporal variations in physico-chemical factors and Chl a were measured. Abundance ranged from 0.2×104 to 23.09×104 cells ml−1, whereas the biomass ranged from 0.19 1 to 23.01 µgC l−1 in the bay. Synechococcus was found most numerous during September 2005 in the shallower part of the bay while the population was observed least during November 2004 and January 2005. The contribution of <3 µm size fraction to total Chl a ranged between 48% and 74%, being low during the cold period and higher during the warm period. The observed spatial and temporal fluctuations in abundance seemed to be closely related to environmental conditions in the area. Small-sized phytoplankton dominated the bulk of biomass, at least for the summer period.

SPATIAL AND TEMPORAL DISTRIBUTION OF MARINE CLADOCERAN SPECIES IN THE SURFACE WATERS OF ISKENDERUN BAY

Cladocerans are important member of pelagic ecosystem and they serve as good sources of food for fish and fish larvae during the warm periods. The aim of this study was to determine species composition of marine cladocerans and their temporal and spatial distribution in the surface waters of coastal and offshore waters of Iskenderun Bay. The study was conducted at the four stations in Iskenderun Bay between November 2005 and August 2006. The samples were collected horizontally with WP-2 net (200 mesh size). Six species of cladocerans ( Penilia avirostris, Evadne spinifera, Pseudoevadne tergestina, Evadne nordmanni, Pleopis polyphamoides and Podon intermedius ) were found. Among these, Evadne nordmanni was observed for the first time in Iskenderun Bay. With regard to annual abundance of cladoceran species, Evadne spinifera was the most abundant and followed by P. avirostris and P. tergestina . While the maximum abundance of cladoceran was observed in May-06, the minimum abundance was in November-05. It can be concluded that results of this study could provide a significant contribution to the future studies on cladoceran diversity in the region.