Statistical Analysis of Local Oceanographic Variability Relative to Abalone Habitats at Isla Natividad

Abalone are an economically and ecologically important marine organism along the Pacific coast. The growth and survival of these species are sensitive to water quality parameters, particularly temperature and dissolved oxygen (DO) concentration. However, climate change is causing ocean warming and deoxygenation. When these large scale trends are combined with natural storm and upwelling events, the frequency, intensity, and duration of temperature and low DO events may affect abalone population persistence at local scales. Here, we undertake a first-pass analysis of the oceanographic conditions of two locations in Baja California as a part of a larger effort to forecast the persistence of spatial refuges. Oceanographic condition data from 2013 to 2018 was provided by a multi-institutional collaboration from two moorings. One mooring off Morro Prieto faces offshore towards the Pacific Ocean; the other, off Punta Prieta, faces the Baja mainland. We used time series analysis methods implemented within R and RStudio to identify extreme values, long-term and short-term variability, as well as the relationship between temperature and dissolved oxygen. In addition to time series analysis, we compared DO and temperature parameters with published observations of stress and mortality in abalone within the two sites. Our results suggest that differences in oceanographic conditions can manifest on a local scale: the total duration of time above the preferred temperature of green abalone in Morro Prieto was roughly 500 hours compared to 156 hours in Punta Prieta, while the time below the threshold of DO was approximately 3756 hours in Morro Prieto compared to 237 hours in Punta Prieta, implying that the environment in Punta Prieta may pose more adaptational challenges compared to conditions in Morro Prieto.