Ocean conservation and management requires understanding spatially-structured community dynamics for tens or hundreds of interacting vertebrate species in a highly variably environment. Recent advances in multispecies spatio-temporal models provide a unified analysis of population, habitat, climate, and ecosystem status. As case studies for spatio-temporal community analysis, I discuss two models available in a spatio-temporal fisheries toolbox, www.FishStats.org. Specifically, I first use a joint dynamic species distribution model (JDSDM) to estimate the multidecadal variance in site-specific biomass for numerically dominant species in each of seven marine ecosystems. I then demonstrate how aggregate variance is buffered by asynchronous fluctuations in biomass among species and locations, and examine changes in buffering among decades. I also demonstrating using a vector-autoregressive model (VAM) of species interactions to estimate the impact of recovering grey seals on prey fishes in the Gulf of St. Lawrence, including symmetric responses to environmental drivers and asymmetric impacts of density changes for each species on per-capita productivity of other species.
Preliminary results using the JDSDM for seven marine ecosystems suggests that these ecosystems include areas with relatively greater or lesser buffering due to species asynchrony. Importantly, synchrony (aggregating across species and areas) has increased in the Celtic Sea and Eastern Bering Sea – this increased synchrony was possible in the Celtic Sea because spatial synchrony was already high, resulting in a higher mathematical limit for total synchrony across species and sites. Meanwhile, the VAM for the Gulf of St. Lawrence suggests that grey seals have strongly impacted prey including thorny skate, particularly near haul-outs with greatest local increases in seal density. Notably, this community shows “partial regulation”, where the axis of community covariation associated with recovering seals is indistinguishable from unregulated dynamics. Both case studies illustrate the potential for synoptic analysis of spatially-structured dynamics for marine vertebrate communities worldwide. I hypothesize that the unified analysis of population, habitat, climate, and ecosystem impacts will allow for improved scientific communication among diverse ocean stakeholders.