Benthic macro-invertebrate fauna and "marine elements" sensu Annandale (1922) Highlight the valuable dolphin habitat of river Ganga in Bihar - India

Abstract

From the main channel of River Ganga 95 invertebrate taxa have been recorded in the endangered Gangetic Dolphin (Platanista gangetica) habitat over an observation period of ten years. Mollusks, Annelids and Arthropods are the dominating benthic groups that constitute the detritivores, filter-feeders and sediment feeders, scrapers/grazers and herbivores. The benthic sediment fauna is rich in diversity and high in abundance. This enables carnivores to occupy a large variety of specialized ecological niches. The qualitative faunal composition of Ganga resembles in general large European rivers with similar representation of taxa. Twelve taxa of marine-originated families were identified, but none of them can be classified as invasive or non-indigenous species. Only two taxa are certainly recognized as non-indigenous neozoans, whereas the remaining fauna shows pristine and stable ecological conditions. In this aspect River Ganga differs from regulated large rivers, where faunal change has largely replaced the original species inventory. Despite the heavy pollution in parts of the river, the original composition of biological diversity is still persisting in the middle reaches of the Ganga. This provides hope for the survival of the Gangetic Dolphin.

Discovery of a silicate rock-boring organism and macrobioerosion in fresh water

“…Our discovery of a freshwater rock-boring assemblage in the Kaladan is in agreement with numerous occurrences of marine-derived groups in rivers of the Oriental Region, which have attracted the attention of scientists for many decades 27 , 30 , 42 – 45 . Fossil freshwater shark assemblages were discovered from the Late Jurassic and Early Cretaceous deposits of the Khorat Plateau in Thailand 46 , 47 indicating that the colonization of Asian river systems by marine animals started as early as the mid-Mesozoic.…”

“…In contrast, at least one member of the rock-borer’s assemblage, the sponge C. ultima , is an entirely freshwater species that is not known from brackish water bodies 28 . The freshwater fauna of the lower and middle reaches of the Kaladan and Lemro River systems appears to be rather a derivative of the Indian fauna (e.g., indicator taxa such as N. gangetica 29 , 30 , Lamellidens aff. marginalis 31 , 32 , and C. ultima 28 ), but the lack of comparable molecular data from India precludes any final biogeographic conclusion.…”

Discovery of Novaculina myanmarensis sp. nov. (Bivalvia: Pharidae: Pharellinae) closes the freshwater razor clams range disjunction in Southeast Asia

“…This barrier could have existed during most of the Cenozoic Epoch 34 , although it may have occasionally been incised, but not breached, at the Isthmus of Kra 33 . Our statistical biogeographic modeling strongly supports the hypothesis 4 , 6 , 18 that the genus Novaculina is a relict, marine-derived freshwater clade. Similar examples of such secondary freshwater lineages are known among a variety of other taxa, e.g.…”

“…Ganges River and its tributaries in India and Bangladesh ranging from the delta to at least 1,500 km upstream 7 , 8 , 17 , 18 , Buriganga and Pashur river systems in Bangladesh 19 , 20 , and Kaladan and Lemro rivers in Myanmar 4 .…”

Mieniplotia scabra (Müller, 1774), another gastropod invasive species in Europe and the status of freshwater allochthonous molluscs in Greece and Europe

“…Mieniplotia scabra (Müller, 1774) is a freshwater gastropod belonging to the Thiaridae Troschel, 1857, a family that in Europe includes another alien invasive species: Melanoides tuberculata (Müller, 1774). The original distribution includes a large area of the Indo-Pacific coasts and adjacent islands, from central-east Africa to south Asia and north-east Australia (Davis & Yamaguchi, 1969;Pace, 1973;Brandt, 1974;Starmühlner, 1976Starmühlner, , 1979Brown, 1980;Burch, 1980;Starmühlner, 1982Starmühlner, , 1983Starmühlner, , 1984Subba Rao, 1989;Nesemann et al, 2007;Glaubrecht et al, 2009;Dunga et al, 2010;Nesemann et al, 2011;Budha, 2012;Glöer & Pešić, 2012;GBIF, 2014). In Africa, the species lives in eastern South Africa, Kenya, Tanzania (Wami and Kingani rivers, Zanzibar, Pemba Island), Madagascar, Comore Islands, Seychelles Islands, Reunion, Mauritius (Rodriguez Island included).…”