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Description
Detailed methods are described in the associated manuscript (Hydrology-mediated ecological function of a large wetland threatened by an invasive predator) and publications cited within. Long-term monitoring sites were established across the Everglades as part of the Modified Water Deliveries to Everglades National Park project. From July 1996 through February 2022 fish and invertebrates were collected using 1-square meter, 2-mm mesh, throw traps following standardized protocols at three sites in Taylor Slough; sampling also occurs in Shark River Slough, Water Conservation Area 3, and the C-111 Panhandle regions. The southernmost, longest hydroperiod site (CP) in Taylor Slough consisted of three 1-ha plots, while the upstream sites (TS, MD) consisted of five plots per site with two of the five plots having shorter hydroperiods. Seven throw-trap samples were collected at each plot during each sampling period except when sites were only accessible by helicopter and five throw-trap samples were collected; our analyses here are on plot-level mean densities of small fishes and decapods. Samples were collected during five months of each year, starting after the onset of the wet season (begins in June), with wet-season samples collected in July and October, transition period samples collected in December, and dry-season samples collected in February and April. Animals were removed from throw traps following a standard protocol using bar seines and dip nets; vertebrates were euthanized using MS-222 and all animals were fixed in formalin before being transferred to ethanol and identified. From 1997–2021, the nine central/deeper plots in Taylor Slough were sampled with an airboat-mounted electrofisher for three transects of five minutes (pedal time) to assess large fishes (>8 cm standard length) providing catch-per-unit-effort (CPUE) relative abundance values. Native fishes were released and non-native fishes were euthanized following each electrofishing transect. Electrofishing CPUE data were used to assess predator effects in supporting analyses. This electrofishing dataset included only nine plots in Taylor Slough because four of the thirteen plots in Taylor Slough were not sampled by electrofishing, while dry-season electrofishing sampling is limited most years because airboats cannot access sites (throw-trap sampling continues when accessed by helicopter). To partially overcome limitations of missing dry-season sampling, we created indices of annual predator CPUE caught via electrofishing by averaging the total number of fish caught across all electrofishing transects during both wet-season sampling periods (July, October).