Evaluating Temporal Consistency in Marine Biodiversity Hotspots

Abstract

With the ongoing crisis of biodiversity loss and limited resources for conservation, the concept of biodiversity hotspots has been useful in determining conservation priority areas. However, there has been limited research into how temporal variability in biodiversity may influence conservation area prioritization. To address this information gap, we present an approach to evaluate the temporal consistency of biodiversity hotspots in large marine ecosystems. Using a large scale, public monitoring dataset collected over an eight year period off the US Pacific Coast, we developed a methodological approach for avoiding biases associated with hotspot delineation. We aggregated benthic fish species data from research trawls and calculated mean hotspot thresholds for fish species richness and Shannon’s diversity indices over the eight year dataset. We used a spatial frequency distribution method to assign hotspot designations to the grid cells annually. We found no areas containing consistently high biodiversity through the entire study period based on the mean thresholds, and no grid cell was designated as a hotspot for greater than 50% of the time-series. To test if our approach was sensitive to sampling effort and the geographic extent of the survey, we followed a similar routine for the northern region of the survey area. Our finding of low consistency in benthic fish biodiversity hotspots over time was upheld, regardless of biodiversity metric used, whether thresholds were calculated per year or across all years, or the spatial extent for which we calculated thresholds and identified hotspots. Our results suggest that static measures of benthic fish biodiversity off the US West Coast are insufficient for identification of hotspots and that long-term data are required to appropriately identify patterns of high temporal variability in biodiversity for these highly mobile taxa. Given that ecological communities are responding to a changing climate and other environmental perturbations, our work highlights the need for scientists and conservation managers to consider both spatial and temporal dynamics when designating biodiversity hotspots.

Continental‐scale hotspots of pelagic fish abundance inferred from commercial catch records

“…A natural way of quantifying the consistency of hotspots through time is to determine the frequency with which a given site exceeds a chosen hotness level. Piacenza et al () proposed a ‘universal’ threshold in the form of a mean value across years, whereas Santora and Veit () recommended that one standard deviation above a grand regional mean (> 1SD) be used as a common cut‐off to align with previous work on remotely sensed patterns in ocean colour (Suryan, Santora, & Sydeman, ) and krill and whale distributions (Santora & Reiss, ). Although pragmatic, neither approach was feasible in the present study, and future efforts should be made to characterize hotspot variability based on finer‐scale time‐series data.…”

Marine Threats Overlap Key Foraging Habitat for Two Imperiled Sea Turtle Species in the Gulf of Mexico

“…These results provide guidance for conservation of GoM habitats. By identifying these turtle-and threat-co-occurrence hot spots, optimization of limited conservation resources is possible (Piacenza et al, 2015).…”

Joint dynamic species distribution models: a tool for community ordination and spatio‐temporal monitoring

“…Finally, there is great need for determining whether 'hotspots' in species richness or density change substantially over time. Hotspots are frequently used in conservation efforts when planning spatial protection of harvested or imperilled species, and changes over time in the location of hotspots have substantial implications for the usefulness of these spatial protections (Piacenza et al, 2015).…”