Spatial datasets for Victorian kelp dynamics

<p class="MsoNormal"><strong><span>Aim:</span></strong><span> Kelp forests throughout temperate regions of the world serve as foundation species that play a critical role in sustaining the health and function of marine ecosystems but are experiencing declines in abundance due to loss in resilience as the ocean clim</span><span>ate changes. Ocean warming along southeast Australia</span> has already been linked to dramatic losses of kelp species and is contributing to the range expansion and population increases of two species of sea urchin. The purpose of this research is to understand the impact of multiple stressors on the decline in kelps in this region.</p> <p class="MsoNormal"><strong>Location:</strong> Coastal waters off Victoria, Australia</p> <p class="MsoNormal"><strong>Methods:</strong> <span>In this study, we use long-term (&gt; 20 years) datasets on biological observations across Victorian waters to determine trends in coverage and the impact of multiple environmental variables (temperature, habitat, currents, waves, connectivity, urchin abundances) on two important kelps that serve as foundation species (<em>Phyllospora comosa</em> and <em>Ecklonia radiata) </em>using boosted regression trees. These models were then used to develop predictive distribution models for each species and also to predict areas of future risk. </span></p> <p class="MsoNormal"><strong><span>Results:</span></strong><span> We found that both kelp species are decreasing in percent coverage over time and multiple environmental variables, including increasing temperatures, intensifying wave energy, changes in currents and recruitment patterns, and increases in urchin populations are all contributing to the declines of kelps. Additionally, future projections of temperature and wave energy show that these species will likely continue to decrease across 71% of Victorian waters. </span></p> <p><strong><span>Main Conclusions:</span></strong><span><strong> </strong>This information can help to better manage these important foundation species by providing maps of their current and past distributions, along with projections of climate change, to target different areas for urchin culling or macroalgae restoration to reduce future losses.</span></p>