Kelp and Shallow-Reef Ecosystems: Baseline Data and Long-Term Trends Using Historical Data for the South Coast

Our approach to creating a baseline characterization of kelp and shallow (less than 30-meters depth) rock ecosystems in the South Coast Study Region involved (1) new surveys of targeted elements of kelp forest and rocky reef ecosystems using SCUBA and (2) analyses of existing historical datasets on rocky reef ecosystems. To characterize kelp forests inside and outside of the recently established MPAs of the Southern California Bight, we used visual SCUBA surveys to assess habitat characteristics of the rocky substrate and the major players in the kelp forest community, including fishes, mobile and sessile invertebrates, and algae. Depending on the morphology and lifestyle of each species, abundance was estimated using swath surveys that count individuals within a defined area, or uniform point contact surveys that estimate the percent cover of colonial and other species for which distinguishing individuals is challenging. These baseline surveys allow us to understand the initial condition of the kelp forest communities inside and outside of MPAs at the time of MPA implementation and will provide a valuable reference point for interpreting any changes to these communities in the future. The scope of what is being accomplished is unprecedented for a habitat in a single study region associated with the MLPA and its implementation in California. The SCSR consists of as much coastline (1197.2 km) as the rest of the state. In addition, this spatial challenge extends to the number of MPAs: 41 of 50 MPAs in the SCSR have rocky reefs and excluding special closures (15 MPAs), this is nearly half of the MPAs in California (N = 109). We systematically surveyed 94 of the 122 nearshore rocky reefs in the SCSR. This synoptic baseline survey was conducted at 75 individual sites in 2011 and 88 sites in 2012. In addition, we incorporate two similar ‘historical’ data sets from 59 sites in 2004 and 79 sites in 2008.