EAT-SLE-2023

Along the California Current Ecosystem (CCE), Point Conception is an important transition zone between the central and southern biogeographic regions in this eastern boundary current. Within the CCE, there are five National Marine Sanctuaries (NMS), or regions designated as cultural and/or ecological importance, however the productive transition zone around Point Conception is a large gap in the NMS system. The proposed Chumash Heritage NMS (CHNMS) would encompass Point Conception and connect to Monterey Bay NMS in the North, down to the Santa Barbara Channel in the South and extend offshore to include ecologically important deep sea habitats including Santa Lucia Bank. CHNMS is currently going through public comment and review by NOAA’s Office of NMS. This region is also under negotiations for offshore wind energy, which will likely lead to a compromise in shifting CHNMS boundaries to accommodate these wind farms. Our proposed sampling location is the northern Santa Lucia Escarpment, which is in one of these regions that is under consideration for removal from the CHNMS designation. Although there has been heavy sampling in the southern part of the Santa Lucia Bank and southern section of the escarpment (e.g. CalCOFI, buoys), the northern part has had limited exploration. We were alerted to this region by using historic seabird data (1980-2017), where we found that the northern section of the escarpment captures higher seabird relative abundance (# of birds per km 2 surveyed) and diversity (Shannon Index and Simpson’s Index) compared to the southern section and other offshore regions surrounding this area. On a recent mini-CalCOFI cruise to this region (October 2022), we recorded high numbers of both minke and humpback whales within a 20 km longitudinal transect, which supports the hypothesis that this area has enhanced marine predator presence. These observations led to the question of what could be the drivers of these patterns and are these observations of abundant marine predators an indicator of an underlying productive region that has yet to be identified? To answer this, we need a better understanding of the bottom-up processes in this region, and to characterize other components of this offshore food web. We propose to revisit the northern Santa Lucia Escarpment and survey along and across this slope from the Santa Lucia Bank to its depth (~4,000 m). Along this slope, we will gather data on local water masses and currents, chlorophyll patterns, the abundance and community of lower trophic level organisms, and collect additional data on seabirds and marine mammals to investigate this potential ecological hotspot. In addition to our focus on this region, we will also collect seabird, mammal, and water mass data from transects around the escarpment to further understand ecological patterns in this region and put our focused results in the context of the surrounding region. This cruise will not only fulfill our goals of understanding of the bottom-up processes in this region and characterizing other components of this offshore food web, but will also assist with some of the participants PhD research.