Nursery function of mangrove creeks in temperate climates for estuarine fish

Coastal habitats are recognised for their role as nurseries for fish. However, there are conflicting results on whether fish are using mangrove habitats primarily for shelter or feeding grounds, making it challenging to generalise their ecological value for fish. The objective of this study was to investigate whether fish communities use mangroves in temperate climates as feeding grounds. Fyke nets were set during an outgoing tide to assess the fish communities found within mangrove creeks at high tide in the Austral spring and summer. Gut content analyses were conducted to assess diet, and samples were collected for prey availability (i.e. plankton, macroinvertebrates, and meiofauna). The mangrove creeks were used by small-bodied fish, including adults of small species or juveniles of larger species, which occurred in greater abundances in spring than summer. Feeding intensity (GFI) of fish was low, reflecting the low abundances of potential prey found in the mangrove creeks. This suggests that small-bodied fish may not use the mangrove creeks as potential feeding grounds. There is a possibility of fish using mangrove habitats at high tide for shelter while they rely on adjacent habitats (e.g. seagrass meadows) to feed, highlighting the relevance of habitat heterogeneity of tidal wetlands for ecosystem services.