The eastern Mediterranean is naturally highly oligotrophic, but urbanization along the Levant coast has led to raised organic and nutrient loads. This study tracks living foraminiferal assemblages at two sites near an activated sewage sludge outfall from 11/2003 to 5/2004. Oligotrophic site PL29 shows seasonal variations in O2, chlorophyll a, and organic carbon, and has an abundant, diverse benthic foraminiferal assemblage living at various in-sediment depths. At eutrophic site PL3, ∼16 years of sludge injection favor a depleted assemblage primarily of opportunist foraminifera. This site shows less seasonality, is subjected to organic matter overload, O2-stress, and periodic anoxia, foraminifera are less abundant and diverse, and live at shallower depths. The assemblages at both sites represent a common pool of species, with Ammonia tepida highly dominant. Benthic foraminifera were therefore found to be sensitive to trophic trajectories, respond on sub-seasonal time-scales, and track injection and dispersal of organic loads on the shelf.
Bibliographical noteFunding Information:
This project was funded by the Israel Science Foundation (Grant No. 145/02-13.0). At IOLR, the captain and crew of the R/V Shikmona are thanked for their expertise in the oceanographic sampling program. Z. Rosentraub, N. Kress and E. Shoam-Frider, with the technical assistance of E. Shefer, Y. Gertner, Y. Suari, L. Israelov and G. Feinstein of the Marine Chemistry department of IOLR, Haifa, performed sampling and laboratory chemical analysis. Y. Yacobi, IOLR Kinneret, introduced the Chl a measurement techniques. B. Schilman, with technicians M. Kitin, Y. Nahamias and Y. Lacatush of the GSI, assisted in the marine sampling program and in the laboratory procedures. Editor G. Sheppard and reviewer F. Frontalini are thanked for suggestions resulting in a significantly improved manuscript.
- Activated sludge
- Eastern Mediterranean
- Living benthic foraminifera
- Organic carbon