Decadal trends in marine reserves reveal differential\ud rates of change in direct and indirect effects

摘要

Decadal-scale observations of marine reserves suggest that indirect\udeffects on taxa that occur through cascading trophic interactions\udtake longer to develop than direct effects on target species.\udCombining and analyzing a unique set of long-term time series of\udecologic data in and out of fisheries closures from disparate\udregions, we found that the time to initial detection of direct effects\udon target species (±SE) was 5.13 ± 1.9 years, whereas initial detection\udof indirect effects on other taxa, which were often trait mediated,\udtook significantly longer (13.1 ± 2.0 years). Most target\udspecies showed initial direct effects, but their trajectories over time\udwere highly variable. Many target species continued to increase,\udsome leveled off, and others decreased. Decreases were due to\udnatural fluctuations, fishing impacts from outside reserves, or indirect\udeffects from target species at higher trophic levels. The average\udduration of stable periods for direct effects was 6.2 ± 1.2 years,\udeven in studies of more than 15 years. For indirect effects, stable\udperiods averaged 9.1 ± 1.6 years, although this was not significantly\uddifferent from direct effects. Populations of directly targeted\udspecies were more stable in reserves than in fished areas, suggesting\udincreased ecologic resilience. This is an important benefit of\udmarine reserves with respect to their function as a tool for conservation\udand restoration.