BGU Foram's Lab
Dr. Sigal Abramovich
Foraminifera as a model for thermal stress
The eastern most part of the Mediterranean is characterized by extreme oligotrophy and high salinity and temperature values that show a gradual rise over the past few decades. This study follows a similar one conducted in 2007 in a unique natural experimental laboratory setting of the Hadera power plant thermal plume using benthic foraminifera as a model system to investigate the effects of temperature changes. Since that study was conducted a desalination plant started working near the power plant so that in addition to the temperature, salinity is also slightly elevated. This research is now renewed with a new collaboration with Michal Kucera from Marum, Bremen, Barak Herut (IOLR, Israel) and Ahuva Almogi Labin (GSI). The new study is aimed to investigate the physliological and ecological response of key species living inside the heat plume by combining field and laboratory experience.
Temperature and foraminiferal records from Hadera plume and the control station in Nachsholim The temperature in the plume is significantly higher than of the natural ambient water, reaching 36 ºC and 24 ºC in summer and winter, respectively, compared to 29 ºC and 17 ºC in the control station. The numerical abundances of foraminifera in the plume vary from high values in spring of ~ 300 specimens/g compared to ~ 70 specimens/g in February and July.
Benthic foraminiferal response to the removal of fishcages
Worldwide, a significant part of the fish industry is based upon rearing fish in cages, usually at areas close to shore. Those facilities have a significant influence on the immediate environment and the benthic organisms beneath them due to the release of organic material and nutrients that can cause eutrophication in the water column and hypoxic-anoxic conditions in the sediment.For about 18 years, fish cage aquaculture facilities were located at the northern end of the Gulf of Eilat, about 300 m offshore and very close to the Israeli-Jordanian border. Rising concerns about the potential damage inflicted on the gulf’s ecological system and littoral environment was the center of a heated scientific, legal and public debate that ended with the National Council of Planning and Construction ordering their complete removal, which occurred in June 2008. The cessation of open water fish cage aquaculture operations in the Gulf of Eilat has created a unique opportunity to monitor the process and assess the time that is required for the benthic environment to rehabilitate. The goal of this research was to monitor the changes in the benthic foraminiferal assemblages in the area where the fish cages were located, and use these data as a measure for the rehabilitation of the benthos.
The active fish cages severely impacted the sediment underneath, resulting in a benthic environment without living foraminifera. Living foraminifera first appeared in the sediment in January 2009, progressively increasing in abundance thereafter. A clear difference in the rate of the rehabilitation process was observed on a spatial scale, related to distance from the point source of the organic enrichment. The growth of the seagrass H. stipulacea in the previously impacted sediments indicates environmental recovery in general, and supplies a substrate for epiphytic foraminifera.
Department of geological and Environmental Sciences