The Abundance, Distribution and Diversity of Benthic Invertebrates of Lake Malombe | Chapter 04 | Advances in Agriculture and Fisheries Research Vol. 1
The benthic zone of Lake Malombe was
sampled for invertebrates, fungi and bacteria using an Ekman Grab measuring
15.2 cm by 15.2 cm. Thirty-six stations were surveyed for macro-invertebrates
which were identified to the lowest taxa and enumerated to estimate abundance
for the lake. The biomass of macro-fauna is being reported here for the first
time and coincides with a decline in fish catches on Lake Malombe. Snails were
the most dominant macro fauna, belonging to four genera Melanoides, Bellamya,
Bulinus and Lanistes with the mean densities of 177.5, 34.7 and 4.3 and 0.1 m-2
individuals, respectively. Blood worms and Tubifex were also present. Although
there are few such studies in Malawi, it was generally postulated that
dominance of snails is a recent phenomenon following previous studies which
showed the invasion of a form of Melanoides of Asian origin; its success might
be responsible for its proliferation. The benthic substrate was mainly composed
of mud, clay granules, sand and bedrock. The prevalence of Melanoides species
and other high pollution tolerance species suggests that there is high ecosystem
modification due to anthropogenic activities including sediment and nutrient
loading from agricultural practices in the surrounding area. Compared to Lake
Malawi and Upper Shire, Lake Malombe is by far the most productive. There were
significantly higher (P<0.5) densities of aerobic, anaerobic bacteria and
fungi, demonstrating the importance of the detrital food chain. Therefore,
future programs aimed at enhancing fish restoration in Lake Malombe would be
advised to include a suite of bottom feeding fish species. The state of benthos
found in Lake Malombe is an indication of confounding impacts of over-fishing,
climate change and catchment-wide activities. Thus, use of QIIME software could
unravel microbiome characteristics, including climate change signatures.
Similarly, further studies on food webs could contribute to a better
understanding of the Lake Malombe trophic functions.
Author(s) Details
Dr. Orton V. Msiska [Ph.D.]
Fisheries Consultant, P.O.
Box 833, Mzuzu, Malawi.
James Banda
Fisheries Research Unit,
P.O. Box 27, Monkey-Bay, Malawi.
Barnett Kaphuka
Fisheries Research Unit,
P.O. Box 27, Monkey-Bay, Malawi.
View Volume: http://bp.bookpi.org/index.php/bpi/catalog/book/138
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