Shark & MPA WatchMarch 7 2017
Shark Watch is an ongoing research and citizen scientist project assessing shark & ray populations and critical marine habitat in the San Francisco bay and coastline on iNaturalist. We also survey eelgrass habitat for elasmobranchs and fishes by dive survey & using the Trident ROV for applied restoration and protection. The MPA Watch component applies the Trident to documenting species and assemblages in our State Marine Protected Areas for species, ID, populations, presence absence and change over time.
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With a National Geographic team, we explored Kiel Cove to search for eelgrass habitat and sharks on the Tiburon Peninsula using the Trident drone. On a cool, sunny day with a brisk North wind, we arrived in the sheltered cove off the Tiburon peninsula known to have healthy eelgrass beds. There was evidence of a recent herring spawn with active seal ions, harbor seals, grebes and cormorants foraging. We deployed the Trident and had a successful documentation of eelgrass beds (Zostera marina). The buzz along the bottom gave me great confidence we can document sharks although we did not see any this trip.
Hound sharks and rays use eelgrass as a preferred habitat to forage, so we will keep looking for them at herring spawns with the Trident. Eelgrass is also critical habitat for many species and is in great decline globally. It is preferred spawning habitat for Pacific herring and refuge for invertebrates like Dungeness crab, and other species. We did see epiphytic algae and Isopods (Corophium sp.) on the blades, but no signs of Phyllaplysia taylori, the Zebra sea hare or Taylor's Sea Hare, that uses eelgrass habitat grazing on the epiphytic growth. The Trident should be a good tool for scanning for this tiny endemic nudibranch- thought to have been impacted by the heavy flows of freshwater flowing into the San Francisco Bay in 2017. Our youngest intern Luca came along and adeptly piloted the drone. We will continue in Aquatic Park and Richardson Bay during the winter season in anticipation of the hound shark and ray pupping season. Late spring we will re-launch our vessel after a refit and begin exploring and documenting our coastal MPAs.
Our team of marine science graduate students have dived the Aquatic Park Cove to look for presence of eelgrass and map it. Using the Trident we were able to verify some eelgrass although the heavy influx of freshwater appears to have greatly reduced the abundance.
Although in very low visibility- and difficulty navigating along the bottom in the current, we were able to identify several invertebrates and three species of marine algae using the drone. These will go into the species list we are collecting and onto the iNaturalist platform already started by our Bio Blitz this year.
We plan to use the ROV in clearer water this winter. We have seen several species of small sharks and hope to verify presence absence using the drone, fishermen interviews and direct observation. Last year we did recover one moribund leopard shark and provided the sample to the Dept. Fish and Wildlife pathologist (which came up positive with M avidus, the ciliated protozoan associated with the shark die off in 2017.)
We are hoping to potentially restore and protect eelgrass beds in the Aquatic Cove Park and continue monitoring for the health of sharks and rays and benthic habitat.
As co-chair of the Golden Gate MPA Collaborative we will apply the Trident to survey eelgrass habitat inside the San Francisco Bay in comparison to areas inside MPAs currently surveyed using snorkel survey at Drakes Estero. Our collaborative team will also use the ROV as a survey and monitoring tool for marine habitats outside the Golden Gate in the State MPA network.
Shark Stewards is collaborating with the National Park Service at the San Francisco Maritime National Historic Park to assess marine species and habitat in Aquatic Cove and develop new opportunities for youth and public education. This program will include cataloguing marine species from invertebrates to sea birds, on pilings, the municipal pier, in the cove including subtidal habitat using a Trident ROV by Open Explore.
Eelgrass beds will be mapped in the cove using the ROV along transect lines in a baseline survey. Using the mounted camera species will be recorded and identified both along the bottom and on pilings. to compile a list of marine life in the Park.
Eelgrass, Zostera marina, is a foundation species critical for the health of the Bay, sequesters carbon, and provides critical foraging, nesting and habitat for many species including the endemic nudibranch Phyllaplysia taylori. Eelgrass beds have been greatly impacted inside the San Francisco Bay. Aquatic Park provides ideal habitat for eelgrass beds and the plant has been identified visually, yet no mapping has occurred.
Viktoria Kuehn, a masters student in the Department of Environmental Sciences at the University of San Francisco will conduct the initial survey in the cove. This baseline survey will provide invaluable information and will be repeatable over time to determine change in the marine ecosystem.
Through subtidal survey we are surveying key eelgrass (Zostera marina) habitat in distinct areas of the San Francisco Bay, critical for many species of invertebrates, fish and marine animals. Applying data acquired by LIDAR and direct survey we will evaluate changes in densities of eelgrass densities and direct impact as a measure of benthic health and changes in Bay and ocean conditions.
A combined public outreach and education project with the National Park Service and Romberg Tiburon Center will help communicate the importance of benthic ecosystems in the Bay, and better understand elasmobranch natural history and movements inside the estuary.