A new species of the true anemone genus Edwardsia, E. isimangaliso sp. nov., is described from th... more A new species of the true anemone genus Edwardsia, E. isimangaliso sp. nov., is described from the St Lucia Estuary, Africa’s largest estuarine lake. The species differs from its closest relatives in anatomy and cnidom and is the only species of the genus found in hypersaline waters. Its current distribution appears to be restricted to a narrow region in the middle reaches of the estuary (lower South Lake), where it has been recorded at salinity levels ranging from 21 to 55.6 psu. The species is also limited to substrata dominated by fine to very fine sand and does not occur in areas with either high silt or coarse sand content. Population densities appear to have decreased over time, with maxima over 1500 ind. m2 recorded in 2005, but only 20 ind. m2 in 2010. Prey items identified in its stomach include the snail Assiminea ovata and ostracods. However, stable isotope analysis showed that the main carbon sources for the anemone are the filamentous macroalga Cladophora sp. and benthic microalgae. The presence of zooxanthellae in tissues of E. isimangaliso sp. nov. suggests that the species may combine heterotrophic and autotrophic feeding modes in response to fluctuations in resource availability.
The date of first introduction of the North-East Pacific acorn barnacle Balanus glandula to South... more The date of first introduction of the North-East Pacific acorn barnacle Balanus glandula to South Africa is unknown, but it is depicted in photographic records dating back to at least 1992. Its present range and population density were determined by surveying 24 sites on the west and south coasts of South Africa. B. glandula occurred over approximately 400 km of coastline, from Elands Bay in the north-west to Misty Cliffs on the west coast of the Cape Peninsula. The abundance of B. glandula was affected by site, zone, prevalence of upwelling, and orientation of the shore. Its distribution was very patchy, both on macro- and microscales, with Bloubergstrand and Moullie Point having the highest abundances of 28 445 and 24 500 individuals m–2 respectively. B. glandula was the dominant barnacle at all West Coast sites where it was recorded, comprising 78.5% of all barnacles found. The successful invasions of B. glandula in South Africa, Argentina and Japan suggest that this species poses a potential threat to intertidal communities in cool, temperate waters.
A new species of the true anemone genus Edwardsia, E. isimangaliso sp. nov., is described from th... more A new species of the true anemone genus Edwardsia, E. isimangaliso sp. nov., is described from the St Lucia Estuary, Africa’s largest estuarine lake. The species differs from its closest relatives in anatomy and cnidom and is the only species of the genus found in hypersaline waters. Its current distribution appears to be restricted to a narrow region in the middle reaches of the estuary (lower South Lake), where it has been recorded at salinity levels ranging from 21 to 55.6 psu. The species is also limited to substrata dominated by fine to very fine sand and does not occur in areas with either high silt or coarse sand content. Population densities appear to have decreased over time, with maxima over 1500 ind. m2 recorded in 2005, but only 20 ind. m2 in 2010. Prey items identified in its stomach include the snail Assiminea ovata and ostracods. However, stable isotope analysis showed that the main carbon sources for the anemone are the filamentous macroalga Cladophora sp. and benthic microalgae. The presence of zooxanthellae in tissues of E. isimangaliso sp. nov. suggests that the species may combine heterotrophic and autotrophic feeding modes in response to fluctuations in resource availability.
The date of first introduction of the North-East Pacific acorn barnacle Balanus glandula to South... more The date of first introduction of the North-East Pacific acorn barnacle Balanus glandula to South Africa is unknown, but it is depicted in photographic records dating back to at least 1992. Its present range and population density were determined by surveying 24 sites on the west and south coasts of South Africa. B. glandula occurred over approximately 400 km of coastline, from Elands Bay in the north-west to Misty Cliffs on the west coast of the Cape Peninsula. The abundance of B. glandula was affected by site, zone, prevalence of upwelling, and orientation of the shore. Its distribution was very patchy, both on macro- and microscales, with Bloubergstrand and Moullie Point having the highest abundances of 28 445 and 24 500 individuals m–2 respectively. B. glandula was the dominant barnacle at all West Coast sites where it was recorded, comprising 78.5% of all barnacles found. The successful invasions of B. glandula in South Africa, Argentina and Japan suggest that this species poses a potential threat to intertidal communities in cool, temperate waters.
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