World Congress of Malacology Antwerp ... - Unitas Malacologica

The impact of urbanisation on freshwater gastropods of L. Jipe, Kenya
Lange, Charles N. 1 ; Kristensen, Thomas K. 2
1. Department of Invertebrate Zoology, National Museums of Kenya, P. O. Box, 40658 – 00100,
Nairobi, Kenya,
Email: Nzavi2001@yahoo.com
2. DBL-Institute of Health Research and Development, Jaegersborg Alle 1D, 2920 Charlottenlund,
Denmark,
Email: tkkristensen@dblnet.dk
The Lake Jipe of southeastern Kenya, is an important freshwater biodiversity conservation centre in
Eastern Africa. It is a hot-spot and centre of endemism for several species of flora and fauna. Despite
the lake biodiversity conservation significance, it is currently experiencing increasing anthropogenic
disturbances mainly assciated with creation of small urban centers mainly to serve the local fishery
activities. Despite the ensuing urbanisation associated with numerous anthropogenic disturbances no
detailed freshwater gastropds studies have ever been executed at the lake. Only one incidental
collection was conducted at the lake nearly over two decades ago. Studies elsewhere suggests the
potential for major impact on gastropods diversity following anthropogenic influences with likely
crucial conservation and medical implications. The present study was thus implemented to
investigate the impact of the urbanisation along L. Jipe on freshwater gastropods diversity patterns.
Snail sampling was carried out at sites around the small urban centers and protected sites within a
nearby national park for comparison using a standard scoop. Fieldwork for the study is just
completed and data processing is ongoing to be completed in a months time then the final report
compilied by end of April, 2007. A complete synthesis of the project findings including the
recommendations will be presented in form of a poster during the forthcoming world congress on
malacology, Antwerpen, Belgium. The study I being implemented with financial support from
International Foundation for Science(IFS).
The molluscan fauna of a deep-water coral community at Rockall Bank (NE Atlantic)
Lavaleye, Marc; Duineveld, Gerard; Schulting, Sanne
Netherlands Institute for Sea Research, Postbox 59, 1790 AB Den Burg, The Netherlands,
Email: lava@nioz.nl
Deep-water coral reef communities occur patchy along the European continental margin, commonly
between depths of 200-1000 m. One of the workpackages within the HERMES project (Hotspot
Ecosystem Research on the Margins of European Seas, 2005-2009) funded by the EU is designated
for research on deepsea coral reefs. One of the goals within this project is to measure the importance
of the benthos within a coral community in respect to biodiversity, density and biomass, and the role
of the different species within this ecosystem.
The living benthos including Mollusca from 6 boxcores taken at and near a coral mound at the SE
slope of the Rockall Bank (500-800m) was identified, counted and weighed. Besides, the trophic
structure of the community was mapped by analysis of the stable isotope(δ15N) signatures of the
most common animals Additionally, the dead shell material from quantitative boxcore samples was
also sorted, identified and counted, to get a time-integrated idea of the biodiversity and density of
molluscs.
Densities and biomass of molluscs are much higher (>20x) within the coral area than in nearby area's
without corals, while biodiversity is 5 times higher. Biodiversity of the dead material (shell gravel)
within the coral area was about 2 times higher than that of the living material. The isotopic signature
of the molluscs was at about the same level as corals, tunicates and crinoids, suggesting that they all
live on the same material by filter-feeding. In conclusion molluscs are important within the corals
because of a high biodiversity, but especially so because of their high relative density and biomass.
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