Abstract
The estuarine pipefish, Syngnathus watermeyeri, is one of the rarest animals in Africa. It currently occurs in only two estuaries on South Africa’s south coast, the Kariega and Bushmans estuaries. The estuarine pipefish was declared extinct in 1994 but was later rediscovered and is currently listed as a critically endangered species. A conservation programme was launched in 2017, whose aims include the re-introduction of captive-bred pipefishes into estuaries where the species was historically present, which requires knowledge of the species’ dietary preferences. In the present study, we used metabarcoding of faecal DNA to identify prey species consumed by wild S. watermeyeri, and compared the species’ diet with that of the longsnout pipefish S. temminckii, which shares its habitat but is very common along much of the South African coastline. Compared to the longsnout pipefish, which consumes a wide variety of prey items, it was found that the estuarine pipefish is much more specialised. Calanoid crustaceans make up 64% of its diet, with mollusc larvae and insects being less important. Our finding supports the hypothesis that population declines and localised extinctions during previous decades may have been the result of reductions in the abundance of their main food source. Calanoid zooplankters rely on freshwater pulses to thrive, but such events have become rare because both estuaries suffer from excessive freshwater abstraction for urban and agricultural use.
M.Sc. (Zoology)