The abundance of an invasive freshwater snail Tarebia granifera (Lamarck, 1822) in the Nseleni River,South Africa

The invasive freshwater snail Tarebia granifera (Lamarck, 1822) was first reported in South Africa in 1999 and it has become widespread across the country, with some evidence to suggest that it reduces benthic macroinvertebrate biodiversity. The current study aimed to identify the primary abiotic drivers behind abundance patterns of T. granifera, by comparing the current abundance of the snail in three different regions, and at three depths, of the highly modified Nseleni River in KwaZulu-Natal, South Africa. Tarebia granifera was well established throughout the Nseleni River system, with an overall preference for shallow waters and seasonal temporal patterns of abundance. Although it is uncertain what the ecological impacts of the snail in this system are, its high abundances suggest that it should be controlled where possible and prevented from invading other systems in the region.     

Studies on the breeding habits and development of the brood-pouch of a viviparous prosobranch; Melania scabra

Studie son the breeding habits and development of the brood-pouch of a freshwater prosobranch, Melania scabra, have revealed that the snail is ovoviviparous, showing parthenogenetic reproduction. The embryos complete their development in a special incubatory pouch called the brood-pouch or brood chamber, and hatch out in a form completely resembling that of the adult. The snail was found to be a continuous breeder, showing gravid condition throughout the year. General structure, development and functions of the brood-pouch were studied in detail. The brood-pouch was found to contain a slightly alkaline albuminous fluid with a pH 7.2, Qualitative and histochemical studies of the brood-pouch revealed the presence of glycogen, fat and protein as the major constituents. These probably play an important role in the nutrition of embryos.