TRACKING AQUATIC INVERTEBRATES IN AN URBANIZED ESTUARY - KEEPING AN EYE ON OAKLAND'S LAKE MERRITT IN 2022-2023

From 1962-1972, James Carlton carried out detailed studies of Lake Merritt’s marine and estuarine life providing an extensive description of species and communities present at that time. A re-survey of the lake was conducted in 2016 by James Carlton of Williams College MA and Andrew Chang of the Smithsonian Environmental Research Center (SERC) Tiburon CA, and an additional SERC team, to determine how the lake communities had changed in 50 years. They reported shifts in community composition, new non-native species, and a notable increase in species common to higher salinity environments. Recently, Lake Merritt has been subjected to 1) a harmful algal bloom (HAB) that decimated fish and many invertebrate populations and 2) a historic series of atmospheric river events causing prolonged freshening and shoreline flooding. The detailed scientific surveys provided by Carlton and Chang provide a baseline from which to view changes occurring after these recent ecological catastrophes.

Rotary Nature Center Friends, an educational non-profit, has involved the local community – local students (K-college, public and private) and interested adults of all ages - in recording the presence of invertebrates on the iNaturalist.org platform. We were making observations, as part of a public outreach event on the day of the fish kill.

Since October 2022, we continue to track invertebrate species at Lake Merritt under a broad citizen-science umbrella: an iNaturalist.org project, Harmful Algal Bloom in Lake Merritt: Are There Any Survivors?, California Academy of Sciences sponsored City Nature Challenge and Snapshot CalCoast events and Biodiversity Days. Preliminary results indicate that recovery of ecological communities in the lake has been surprisingly quick but uneven. We have recruited iNaturalist.org enthusiasts among teens and college students, an under-represented demographic, and encouraged the next generation of naturalists, nature-lovers, and science professionals.