Benjamin Ruttenberg & Rikk Eriksen, Cal Poly San Luis Obispo

Several floating offshore wind (OSW) developments are in the planning stages in California. These OSW projects would be located in the highly dynamic California Current Large Marine Ecosystem (CCLME), where upwelling, mesoscale variability, and climate-driven change structure complex ecosystem processes. They would also use floating platforms instead of fixed bottom platforms and be further offshore and in much deeper waters than other OSW projects worldwide. To support environmentally responsible development, the California Marine Sanctuary Foundation (CMSF), along with California Polytechnic State University, San Luis Obispo (Cal Poly), have developed an Offshore Wind Environmental Monitoring Framework (Framework) in collaboration with a broad network of scientific experts for the State of California. This non-regulatory guidance integrates oceanographic and ecological considerations to inform consistent, scalable monitoring for sustainable OSW development off the CA coast. We present results, recommendations and lessons learned from the process of developing this Framework. Across taxa, several factors emerged as the most likely to produce impacts, including vessel traffic, underwater noise, and offshore infrastructure, and this work identified several key knowledge gaps. Analyses suggest that the magnitude of potential impacts was highly uncertain in many cases. Understanding the existing, preconstruction spatiotemporal variability in oceanographic processes as well as species abundances, distributions, and use of space will be critical to designing and/or repurposing monitoring in the CCLME to detect, minimize, and mitigate the environmental effects of OSW development in California. By making recommendations that contextualize oceanographic processes, the Framework provides a foundation for distinguishing OSW impacts from natural variability and advancing ecosystem-based management in California’s evolving offshore energy landscape.

Allison Dedrick, California Department of Fish and Wildlife

Larvae collected through CalCOFI sampling can be used to develop indices of abundance, potentially providing a source of fishery-independent data to stock assessments. To better understand the potential value of developing CalCOFI indices, particularly for data-limited species lacking other fishery-independent data, we review how CalCOFI larval indices have been modeled and used in assessments to date. CalCOFI indices have been used in a handful of existing assessments for both federally-managed (e.g. bocaccio and chilipepper rockfish) and state-managed species (e.g. southern California halibut and California sheephead). We compare the overlap of the CalCOFI sampling grid with the species’ ranges and assessment boundaries, as well as index modeling choices to explore questions of when CalCOFI data is sufficiently representative of a stock to be used as an index, how to handle data sparseness or gaps, and how best to include a CalCOFI index in an assessment (e.g. as indicative of spawning stock biomass or recruitment). We then turn toward the future to explore additional species with potential for CalCOFI larval indices and modeling techniques that could help expand the utility of CalCOFI larval data. By exploring what makes an index useful, we highlight the value of CalCOFI larval indices as a source of fishery-independent data at a life stage not often otherwise sampled.

Mark Morales, University of Virginia

Global environmental change is driving the redistribution of marine and terrestrial species through spatial differences in survival, reproductive success, and dispersal. Forecasting range shifts with correlative species distribution models (SDMs) generally overlooks the demographic and dispersal processes that determine a species range, often leading to unreliable forecasts in novel environmental conditions. Here, we developed and applied an age-structured dynamic range model (DRM) that allows for spatial- and time-varying survival and recruitment based on environmental conditions. We hypothesized that DRMs improve out-of-sample prediction skill when forecasting into no-analog conditions (i.e., marine heatwave). We applied the DRM to Dungeness crab (Metacarcinus magister), one of the U.S. West Coast’s most valuable commercial species, by using fisheries-independent data from a long-term bottom trawl survey. We evaluated out-of-sample prediction skill by retrospectively forecasting into novel oceanographic conditions characterized by a large marine heatwave. We found that forecast skill was higher for DRMs compared to correlative SDMs. Specifically, forecasts had the highest skill when they allowed recruitment to vary as a Gaussian function of surface seawater temperature and survival to vary as a log-linear function of bottom oxygen concentration. These findings suggest the dominant demographic mechanisms determining local population abundance for this species. More broadly, our results suggest that an explicit consideration of the mechanisms determining a species range will improve forecasts into novel environmental conditions and be able to highlight the abiotic and biotic factors most important to determining a species range. By gaining a better understanding of the processes driving species redistribution, conservation efforts and resource management can also more effectively make decisions in the context of no-analog climates. Broadening our approach to an ecosystem context, our model can be paired with spatial predictions of harmful algal blooms and the distribution of humpback whales to promote climate resilience in the California Dungeness crab fishery.

Victor Mathos, Autonomus University of Baja California

Northern Baja California coast supports major upwelling that sustains highly productive ecosystems; however, the drivers of variability in phytoplankton community structure and the persistence of harmful taxa under contrasting oceanographic conditions remain poorly characterized. This study examines interannual variability in phytoplankton community structure and harmful taxa distribution based on two oceanographic campaigns conducted in July 2023 and June 2024, following an IMECOCAL-type sampling design across eight transects spanning major upwelling centers. Phytoplankton abundance and community composition were assessed through microscopic identification and pigment-based chemotaxonomic analysis (HPLC), complemented by nutrients and hydrographic data. In 2023, phytoplankton abundance ranged from ~ 2 x 103 to 9.1 x 105 cells L-1 (median ~5.3 x 104 cells L-1), with chlorophyll-a concentrations up to ~10 mg m-3 (mean ~1.66 mg m-3), indicating elevated biomass associated with active upwelling and nutrient-replete conditions. Northern transects were dominated by diatoms, particularly Pseudo-nitzschia, including domoic acid producer Pseudo-nitzschia australis and Eucampia zodiacus. In contrast, 2024 exhibited slightly lower median abundance (~4.0 x 104 cells L-1) and comparable chlorophyll-a (mean ~1.54 mg m-3), alongside moderate nutrient concentrations in the upper water column (NO3+NO2: ~0.5-8 µM; PO4: ~0.3-1.2 µM; SiO4: ~2-15 µM). These conditions coincided with a broader spatial distribution of Pseudo-nitzschia and increased relative contributions of nanoplankton, consistent with a shift toward more stratified, regenerated production regimes influenced by mesoscale circulation. The persistence of harmful diatoms across both contrasting years highlights their ecological plasticity and sustained HAB risk potential in this region. These results are consistent with climate-driven reorganization documented in the broader California Current System, where shifts in stratification and circulation restructure phytoplankton communities and promote harmful taxa. Linking regional oceanographic variability with local monitoring efforts provides a critical framework for improving early warning systems of harmful algal blooms in coastal aquaculture under ongoing climate-driven ocean change.

Itzel Mariana Salas Rodela, Universidad Autónoma de Baja California

The Southern California Current System (CCS), a highly productive eastern boundary upwelling regime, exhibits strong thermal variability that influences pelagic community structure. Zooplankton, a key component of marine trophic webs, is particularly sensitive to extreme events such as marine heatwaves. This study evaluates how thermal variability modulates zooplankton community structure across the coastal–oceanic gradient off Baja California, using samples collected during contrasting summer conditions (2023 vs 2024) following an IMECOCAL-type sampling design across eight transects. Satellite SST
anomalies revealed contrasting conditions, with warm extremes in 2023 (>+2.5 °C) and cooler, near-climatological conditions in 2024. The coastal–oceanic gradient was the primary driver of community structure (PERMANOVA: R²=0.156, p=0.001), exceeding interannual variability (R²=0.047, p=0.017). Copepods dominated across all conditions (>64% relative abundance), indicating stability in the main trophic component. However, interannual shifts were evident in secondary taxa: appendicularians ranked second under
warm conditions in 2023 (8.7% coastal, 6.5% oceanic), whereas cladocerans increased markedly during cooler conditions in 2024 (13% coastal; SIMPER contribution ~7%). Rare taxa (e.g., nauplii, ostracods, fish larvae) also increased in relative contribution (~2% to 8.6%), accompanied by higher richness (33 to 38 taxa). These results reveal a hierarchical community response, where dominant taxa remain stable while secondary and rare components are more sensitive to thermal variability, highlighting their potential as early indicators of ecosystem change in the CCS.

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