Long-Term Shifts in Coastal Biodiversity, Monterey Bay, California

Developing a clear understanding of how marine biodiversity has changed over time is critical in the face of both local and global pressures from human activities. However, observations and scientific studies of marine life are often episodic and limited to a few years. As a result, records of basic changes to biodiversity and the environment are often missing. When baseline data are absent, the long-term local ecological knowledge of scientists, naturalists, and others can provide a powerful opportunity to understand the past. In an on-going project to reconstruct ecosystem changes in Monterey Bay, CA, we interviewed approximately 50 people who were students or researchers in Monterey Bay from 1938 to 2019. We document a marked change in the abundance of several species, including a shift in dominance from bull kelp (Nereocystis luetkeana) to giant kelp (Macrocystis pyrifera) and declines in the once common black abalone (Haliotis Cracherodii). This shift in the dominant kelp species and in abalone populations occurred in the 1960s, following the return of sea otters to Monterey Bay.