Assessing the effects of swimming net material on populations of an endangered seahorse

Abstract

The endangered seahorse Hippocampus whitei has declined in abundance as a result of natural habitat loss, and inhabits copper-braided protective swimming nets in Sydney Harbour, Australia. This study tested whether the use of copper-free seahorse-friendly net material has any effect on populations of H. whitei. The effects of net material on seahorse density and population abundance, as well as the effects on fouling epibiota and the abundance of epifaunal seahorse prey, were tested on pre-existing swimming nets as well as installed panels of each net material type. Material type had no effect on the density or population abundance of seahorses on pre-existing or installed panels of swimming net, with no difference in fouling epibiotic growth or mobile epifauna. Because seahorse-friendly nets were not worse than standard nets in these respects, it is recommended that managers take a precautionary approach and deploy nets of seahorse-friendly material to minimise anthropogenic copper entering coastal systems.

Assessing the Effectiveness of Conservation Stocking for the Endangered White’s Seahorse Hippocampus whitei

“…Whilst habitats have declined across its range, H. whitei has shown an ability to adapt by utilising artificial habitats such as protective swimming nets (Hellyer et al, 2011;Simpson et al, 2021a;Simpson et al, 2021b) and purposefully designed artificial habitats known as seahorse hotels (Simpson et al, 2020). It was recently shown that adult H. whitei select artificial habitats over natural habitats (Simpson et al, 2019), similar to that of the only other Endangered seahorse species, Hippocampus capensis in South Africa (Claassens et al, 2018).…”