Natural oligotrophy vs. pollution-induced eutrophy on the SE Mediterranean shallow shelf (Israel): environmental parameters and benthic foraminifera.
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 O(2), chlorophyll a, and organic carbon, and has an abundant, diverse benthic foraminiferal assemblage living at various in-sediment depths. At eutrophic site PL3, approximately 16 years of sludge injection favor a depleted assemblage primarily of opportunist foraminifera. This site shows less seasonality, is subjected to organic matter overload, O(2)-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.
Hyams-Kaphzan
Orit
O
Department of Geological and Environmental Sciences, Ben Gurion University of the Negev, Beer Sheva 84105, Israel. orith@ocean.org.il
Almogi-Labin
Ahuva
A
Benjamini
Chaim
C
Herut
Barak
B
D002244:Carbon / Q000032:analysis; D002734:Chlorophyll / Q000032:analysis; D000077194:Chlorophyll A; D004784:Environmental Monitoring; D005068:Eutrophication; D056908:Foraminifera / Q000145:classification* / Q000254:growth & development; D005843:Geography; D007557:Israel; D008522:Mediterranean Sea; D010100:Oxygen / Q000032:analysis; D012621:Seasons; D012623:Seawater / Q000737:chemistry*; D014876:Water Pollution / Q000032:analysis*
D002734:Chlorophyll; D002244:Carbon; D010100:Oxygen; D000077194:Chlorophyll A