Micheli Duarte de Paula Costa

Long-term assessment of temporal variability in spatial patterns of early life stages of fishes to facilitate estuarine conservation

ABSTRACT Estuaries are among the most productive coastal ecosystems, supporting a wide variety of marine fishes and their early stages. High spatial and temporal variability in estuaries implies that management strategies must incorporate dynamic features to be efficient. In our study, we analysed 13 years of data on ichthyoplankton from the Patos Lagoon estuary (Brazil) to assess whether temporal variability can show distinct spatial patterns of fish eggs and larval distribution and to discuss how these results can be helpful to conservation planning. Spatial patterns of fish egg and larval assemblages were evaluated using cluster analysis. Indicator taxa for each group were also calculated as a product of the relative frequency and relative average abundance in each group. In addition, we used generalized linear models to analyse fish egg and larval abundance in relation to environmental variables. Results showed that fish eggs and larvae exhibit high variability among months, years and sampling stations in the time series. Temporal occurrence and spatial distribution were mainly associated with salinity. We found distinct spatial patterns for fish eggs and larvae in the Patos Lagoon estuary. Groups identified were different among years and indicated by a distinct genus. Our results can be considered as a first exploratory step to help managers to decide which species and temporal scale should be studied in detail and incorporated in management plans. Spatial conservation planning incorporating fluctuations in abundance and assemblage structure over time may help to ensure conservation for biodiversity persistence in highly dynamic ecosystems such as the Patos Lagoon estuary.

Efficiently enforcing artisanal fisheries to protect estuarine biodiversity

Artisanal fisheries support millions of livelihoods worldwide, yet ineffective enforcement can allow for continued environmental degradation due to overexploitation. Here, we use spatial planning to design an enforcement strategy for a pre-existing spatial closure for artisanal fisheries considering climate variability, existing seasonal fishing closures, representative conservation targets and enforcement costs. We calculated enforcement cost in three ways, based on different assumptions about who could be responsible for monitoring the fishery. We applied this approach in the Patos Lagoon estuary (Brazil), where we found three important results. First, spatial priorities for enforcement were similar under different climate scenarios. Second, we found that the cost and percentage of area enforced varied among scenarios tested by the conservation planning analysis, with only a modest increase in budget needed to incorporate climate variability. Third, we found that spatial priorities for enforcement depend on whether enforcement is carried out by a central authority or by the community itself. Here, we demonstrated a method that can be used to efficiently design enforcement plans, resulting in the conservation of biodiversity and estuarine resources. Also, cost of enforcement can be potentially reduced when fishers are empowered to enforce management within their fishing grounds.