Abstract
Benrhic foraminifera (Protista: Sarcodina) are ol1l'-ceUed organisms that are widely spread over the
worlds' oceans. Most of the species can be distinguished by the morphology of their sheJl, and the
high preservation potential of these shells makes them a lIseful tool to date sediment layers and
reconstruct ancient environments. The latter, however, reqUires
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sufficient insight in the t'cology.
After decades of research on the ecology of benthic foraminifera, stiLi more questions than answers
exist. Nevertheless, the last fn-v years we seem to have come closer to some answers through
experimental and monitorIng studies. Whereas experiments are useful because of the possibility to
standardise environmental parameters, monitoring studies are valuable because of repetitive sampling
during one or several years. These time seriL's provide us with knowledge on how foraminiteral
communities change during the seasons, and develop over the years. With tile repetitive sampling of
several s[;l.tions situated within one region we also gain insight in diffcrencn in foraminiferal
community structures OVLT distance.
In a monitoring study of the- northern Adriatic Sea. BannawicUap et a1. (1992) found large seasonal
changes in foraminiferal abundance<; and in-sediment distribution. The combination of food flux and
especially oxygenation of the sediment, was found to playa major role in the foraminiferal
community structures. In 1995, Jorissen et aJ. prese-nted the TROX-model. which describes the
foramjniferal assemblages in the light of these two major controlling f.1ctors. food and oJo,:ygen.
To further unravel the importance of food and oxygen in benthic foraminiferal communities, a
rather large-scale monitoring project was starred in 1996. This project regarded two completely
different regions within the Mediterranean Sea, the eutrophic Adriatic Sea and the oligotrophic
Levantine Basin. [n the Levantine basin, where nutrient levels are known to be low. tht' stability of
the environment was expected to be relatively high. This in contrast with the Adriatic Sea, from
which \vc knew that environmenl,d circuITI<tances change drastically throughout the year, which is
re{Ject by the foraminiferal abundances (Barrnawidjaja et aJ. (992). In order to srudy <;easonal changes
in the foraminiferal communities both study areas were monitored bi-monthly between June '<,16 and
June '98.
In the Levantine basin, Wt' >tudied a down-slope transect perpendicular to the Israeli coast trom 40
to '7oom water depth. Several oceanographic properties (chlurophyll-a, temperature, salinity, and
dissolved oxygen) ,,-c-rc mc-~sllrC'd <illllliunrolldy wirh rhf' samphng of sedirnents. The sediment
oxygenation was measured in detail and hVlllg (Rose Bengal stained) benthic foraminifera were
collected.
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