Biological observations on the crater lakes of Jebel Marra, Sudan

Abstract

With 6 figures in the text)Two lakes lie in a caldera at the top of Jebel Marra. One is shallow and highly saline, with a dense bloom of planktonic blue-green algae and a zooplankton consistingentirely of rotifers.The other is over 100 metres deep, is less saline, with a sparse phytoplankton of diatoms, and the dominant zooplankter is Eucyclops gibsoni. The marginal fauna of the deep lake includes a number of widespread insects, but is unusual in that it includes an aquatic glowworm (Family Lampyridae).In the shallow lake there is a superabundance of oxygen in the upper two metres, but no oxygen below six metres, except when strong winds mix the lake so that there is then about 40% saturation throughout the water column. In the deep lake it was found that after strong winds there was only about 12% saturation in the top 30 metres of water. The restricted fauna of these lakes appears to be a result of the combined effects of isolation, salinity and a variable oxygen regime.

Seasonal dynamics of zooplankton in a shallow eutrophic, man-made hyposaline lake in Delhi (India): role of environmental factors

“…Similarly, no definite pattern of seasonal variations in the population of zooplankton was observed and the zooplankton community was dominated by rotifers, mostly B. plicatilis. Similar observations have also been made from the other saline lakes (e.g., Green et al, 1979;Green & Mengistou, 1991;Pejler, 1995). In addition, the relative contribution of crustaceans to the zooplankton was low, except during spring.…”

The Assess of Pools and Small Lakes as Wetland Sites in Zalingei Area, Darfur, Sudan

“…Seasonal lakes: These are found in different regions and include UmBadir, ElFula, RasAmir, UmBaggara [12]. Craterlakes: Two volcanic lakes are found in JebelMarra (Dariba) and Malha in the Medob Hills [4]. HotSprings: Perhaps Akasha hotsprings, at the tail of Lake Nubia are the most accessible [4].…”

“…Craterlakes: Two volcanic lakes are found in JebelMarra (Dariba) and Malha in the Medob Hills [4]. HotSprings: Perhaps Akasha hotsprings, at the tail of Lake Nubia are the most accessible [4]. Others are found in Quella (JebelMarra), elHarra (wadiAzoom) and in the Meidoub Hills [4].…”

“…HotSprings: Perhaps Akasha hotsprings, at the tail of Lake Nubia are the most accessible [4]. Others are found in Quella (JebelMarra), elHarra (wadiAzoom) and in the Meidoub Hills [4]. Oasis: Nukhaila Oasis, Selima Oasis, Atroun Oasis, elBashiri Oasis [4].…”

“…Others are found in Quella (JebelMarra), elHarra (wadiAzoom) and in the Meidoub Hills [4]. Oasis: Nukhaila Oasis, Selima Oasis, Atroun Oasis, elBashiri Oasis [4]. Mayaas: They are either fed from rivers or by sheet flow or both.…”