Population Structure of an Invasive Parthenogenetic Gastropod in Coastal Lakes and Estuaries of Northern KwaZulu-Natal, South Africa

Abstract

BackgroundEstuaries and coastal lakes receive little attention despite being heavily invaded by non-indigenous invasive species (NIS). In these situations, studies of population dynamics in invaded habitats can provide valuable insights into how NIS interact with new environments. Tarebia granifera is a prosobranch gastropod from south-east Asia which has invaded other sub-tropical parts of the world. This study addresses whether a small number of key environmental factors influences gastropod communities, and specifically how the population density and size structure of T. granifera were influenced by environmental change in estuaries and coastal lakes in southern Africa.Methodology/Principal Findings T. granifera's density, number of brooded juveniles and size structure were measured at the St. Lucia Estuary, Mgobozeleni Estuary, Lake Sibaya and Lake Nhlange. Size structure was classified according to shell height (SH). All dissected individuals were found to be female and free from trematode infection. Salinity, water depth, temperature, and pH were the main factors correlated with population density of gastropod communities. T. granifera often reached densities well over 1000 ind. m−2, displacing indigenous gastropods and becoming a dominant component of the benthic community. T. granifera successfully invaded estuaries despite frequent exposure to high salinity and desiccation, which could together eliminate >97% of the population. The persistence of T. granifera was ensured due to its high fecundity and the environmental tolerance of large adults (20–30 mm SH) which carried an average of 158±12.8 SD brooded juveniles. Repeat introductions were not essential for the success of this parthenogenetic NIS.Conclusion/SignificanceThere is a need for a broader study on the reproductive biology of T. granifera (including the previously overlooked “brood pouch ecology”), which affects population dynamics and may be relevant to other parthenogenetic NIS, such as Melanoides tuberculata and Potamopyrgus antipodarum.

Stable Isotope Evidence for Dietary Overlap between Alien and Native Gastropods in Coastal Lakes of Northern KwaZulu-Natal, South Africa

“…Yet the spatial distribution of T. granifera can simultaneously overlap with that of several species at a time [26]. However, this study does not address the greater complexity of interactions between multiple gastropod species in the same area.…”

“…However, snails like T. granifera do not seem to be successfully predated upon by native species in iSimangaliso, although they can be attacked by birds, fish and invertebrates, such as crabs and leeches. Trematode parasites are also absent in T. granifera [26]. Predators and parasites could regulate populations of alien gastropods [45].…”

“…Tarebia granifera is parthenogenetic and ovoviviparous, giving birth to live juveniles and often reaching population densities of over 1000 ind. m −2 [26]. Tarebia granifera has been successfully used as a biological control of schistosomiasis in the Caribbean, since it is able to displace host native gastropods [27]–[29].…”

Chemical Cues Released by an Alien Invasive Aquatic Gastropod Drive Its Invasion Success

“…Tarebia granifera , a freshwater gastropod endemic to south-east Asia, has invaded many tropical and sub-tropical parts of the world [26] and has most recently become established at the expense of native species in areas of the iSimangaliso Wetland Park and many other shallow water ecosystems in KwaZulu-Natal, South Africa [27]. Generally it has been assumed that T. granifera displaces native gastropods through exploitative competition.…”

Struktur Komunitas Dan Distribusi Temporal Gastropoda Di Danau Situ Gintung, Tangerang Selatan, Banten

“…Hasil yang berbeda dijumpai di Situ Gede Bogor, dimana dua spesies tersebut ditemukan melimpah di musim hujan dan musim kemarau (Priawandiputra et al, 2017). Distribusi temporal populasi T. granifera di ekosistem danau dipengaruhi oleh temperatur, pH (Miranda et al, 2011), zonasi (Vadeboncoeur et al, 2011), salinitas, umur, kedalaman air, sumber makanan (Miranda & Perissinotto, 2012), karakteristik habitat danau (Lange et al, 2013), dan aktivitas manusia (Song et al, 2013).…”