Elemental composition of particulate matter and nutrient dynamics in the Izmir Bay (Eastern Aegean)

Izmir Bay (38°41′–38°21′ N, 26°30′–27°08′ E) is one of the great natural bays of the Aegean Sea. Temporal variations and regional distribution of particulate organic matter, dissolved nutrients and chlorophyll-a were investigated seasonally in the bay. The data were collected during four cruises of R/V K. Piri Reis between March 2000 and January 2001 at selected sampling points within the framework of the “Izmir Bay Marine Research Project”. The composition of particulate matter was determined and evaluated together with physical parameters in Izmir Bay. Due to the atmospheric and land-based nutrient inputs, the levels of nutrients are lower in the outer part than the middle and inner parts of the bay. The particulate concentrations varied between 3.2 and 23 for POC, 0.32 and 2.1 for PON, 0.02 and 0.21 μM for PP in the outer and 12 and 197 for POC, 1.7 and 30 for PON, 0.11 and 1.9 μM for PP in the middle–inner bays. The elemental mean ratios of particulates (POC:PON:PP) from the individual measurements were 166:16:1 and 127:17:1 for the outer and middle–inner bays, respectively. The ratios, derived from the slopes of linear regressions, are quite comparable with the ratio from the preformed nutrient data. Atomic ratios of particulate matter from the regression equations were similar to off-shore Mediterranean Sea and lower than near-shore Black Sea in the outer bay. POC:PON:PP ratios were mostly greater than the Black Sea in the middle and inner bays. Mean DIN:DIP ratios in the water column were 14 and 3.5 in the outer and middle–inner bays, respectively, which are lower than the Redfield ratio.