Title: The Presentlatest Holocene zoobenthos foraminifera records in Lake Qarun, Egypt
1The Present-latest Holocene zoobenthos
(foraminifera) records in Lake Qarun, Egypt
Ramadan Abu-Zied1, K. Keatings2, A. Zalat3 and R.
Flower2 1 Geology Department, Faculty of Science,
Mansoura University 2 ECRC, University College
London 3 Geology Department, Faculty of Science,
Tanta University
2Location of the studied sediments
Q5
Map of Lake Qarun with the location of all coring
and surface-sediment sampling sites.
3Objectives
- Discover the structure, composition of the
benthic foraminiferal ecosystem in sediments of
the lake. - Compare each species of these ecosystem with the
prevailing ecological variables salinity
changes, organic matter (anthropogenic
materials), dissolved oxygen and water depth. - Reconstruction the paleoecological changes in the
studied core, based on the modern analogue.
4Results
- About 15 species recorded in the surface sediment
samples of the lake, then this number decline in
the core materials to three species - Ammonia tepida, Quinqueloculina lata, and
Elphidium excavatum are the most abundant taxa in
the surface and core materials - There is no much deformation in the foraminiferal
shells - All ontogenetic stages of the species present and
tests are mostly intact indicating no signs of
significant transport or sorting.
5The Island
East
West
Census data of benthic foraminifera from the
surface samples, Lake Qarun.
6Favorable ecosystem
Sample 3 (east of the Island)
7Favorable ecosystem
Sample 11 (near the Island)
8Stressed ecosystem
Sample 6 (west of the Island)
9Background about the species
- All the recorded species present today all over
the world in hypo-to hypersaline lagoons,
shallow-normal marine waters or in shallow
brackish marine waters. - Ammonia tepida is euryhaline cosmopolitan
species, tolerant for a wide range of salinity
variations. Laboratory experiments indicated that
such species reproduce only between 13 and 40 .
10- Ammonia tepida never found in an ephemeral lake
subjected to complete dryness during summer as
does Elphidium (Cann and Deckker, 1981). - Occurrence of Brizalina striatula in our records
is interesting, as it occurs today in
Mediterranean Sea under areas of high organic
matter flux. It occupies different levels in the
sediments tracking the summer stratification.
11(No Transcript)
12Conclusion and future work
- The presence of Ammonia tepida in the lake
sediments (grab samples and core) indicate that
the interval scanned by the core (140 cm) must
have had saline water no less than 10, then
increases gradually reaching the present-day
levels (35-40 ). - Absence of Elphidium excavatum from the surface
sediments of the western side (deepest parts)
could be related to the development of dysoxic
environments there as indicated by the presence
of Brizalina striatula.
13- Occurrence of Rosalina bradyi (epiphytic taxon)
in the present-day sediment and the upper part of
the core could be related to the presence of
seagrasses and phytal remnants. - Future Work
- Increase the resolution of the studied materials.
- Find out any ecophenotypes (formae) variations
within each predominant species. Such variations
could be useful for any paleo-environmental
inferences.
14Thank you