Ecophysiology and population dynamics of the alien invasive gastropod Tarebia granifera in the iSimangaliso Wetland Park, South Africa.
Miranda, Nelson Augusto Feranandes.
MetadataShow full item record
Tarebia granifera is a prosobranch freshwater gastropod from south-east Asia which has invaded other sub-tropical parts of the world. This snail has recently also invaded the iSimangaliso Wetland Park, often reaching population densities of over 20000 ind.mˉ2 and dominating benthic invertebrate communities. A multiple method approach was used to address several aspects of the biology and ecology of this non-native invasive species (NIS). The tolerance of T. granifera to salinity and temperature was investigated through the experimental manipulation of these factors. T. granifera survived exposure to temperatures between 0 ºC and 47.5 ºC. More remarkably, this snail was able to survive a salinity of 30 for 65 - 75 days. Population density and size structure were monitored in estuaries and coastal lakes. T. granifera successfully invaded estuaries despite frequent exposure to high salinity and desiccation. The persistence of T. granifera was largely ensured due to the wider environmental tolerance of adults (20 - 30 mm shell height) which carried an average of 158 ± 12.8 SD brooded juveniles. Multiple introductions were not essential for the success of this parthenogenetic NIS. Using gut fluorescence and carbon budget techniques it was estimated that T. granifera consumes 0.5 - 35% of the total available microphytobenthic biomass per day, or 1.2 - 68% of the daily primary benthic production. The carbon component estimated from the gut fluorescence technique contributed 8.7 - 40.9% of the total gut organic carbon content. A stable isotope mixing model was used together with gut content analysis to estimate the diet of T. granifera and dominant native gastropod species, potentially competing for resources. Results were used in the formulation of an index of isotopic dietary overlap (IDO, %). This approach yielded detailed information both on general changes in ecosystem functioning and specific species interactions. Before/After-Control/Impact (BACI) logic was used in a multivariate approach to separate human perturbations from natural spatio-temporal variability displayed by communities, and to further separate perturbations due to NIS. Human intensification of drought negatively affected biodiversity and T. granifera may exacerbate this problem by displacing native species from critical refugia and contributing towards biotic homogenization. The present findings constitute a contribution to the scientific knowledge on biological invasions and a useful tool towards adaptive management in the iSimangaliso Park.
Showing items related by title, author, creator and subject.
Remote sensing of wetland tree species in the iSimangaliso Wetland Park, KwaZulu-Natal, South Africa. Deventer, Heidi Van. (2016)The impact of global change is expected to result in changes in the distribution and composition of species. Coastal swamp and mangrove forests are some of the most threatened forest types in the world. Remote sensing is ...
Towards an architecture that facilitates research and education in a World Heritage Site : an environmental research facility for the iSimangaliso Wetland Park. Bellingan, Mark Lloyd. (2008)The purpose of this research document was to determine a relevant, responsible and appropriate architecture for the design of an Environmental Research Facility for the iSimangaliso Wetland Park World Heritage Site in ...
Impact of turbidity on pseudodiaptomus stuhlmanni, a dominant copepod in Lake St Lucia, iSimangaliso Wetland Park. Jones, Salome. (2015-10-16)Although the St Lucia Estuary is a Ramsar Wetland of International Importance, it has historically been subjected to human-accelerated ecological stressors. One of these is high turbidity resulting from excessive sediment ...