California Sea Grant College Program

El propósito de este documento es compartir una visión estratégica para mejorar la resiliencia costera en la región de San Diego-Baja California a través de la colaboración binacional basada en una evaluación de necesidades liderada por California Sea Grant y Climate Science Alliance.La visión de este documento identifica oportunidades clave y estrategias accionables que integran la investigación científica, el conocimiento tradicional y prácticas innovadoras para apoyar a las comunidades y ecosistemas costeros. Al fomentar asociaciones transfronterizas, expandir las capacidades de investigación y comprometer a diversos actores, este documento tiene como objetivo guiar los esfuerzos hacia un futuro más resiliente para nuestra costa compartida.

The purpose of this document is to outline a strategic vision for enhancing coastal resilience in the San Diego-Baja California Region through binational collaboration. It draws from a needs assessment led by California Sea Grant and the Climate Science Alliance. This vision document identifies key opportunities and actionable strategies that integrate scientific research, traditional knowledge, and innovative practices to support resilient coastal communities and ecosystems. By fostering cross-border partnerships, expanding research capabilities, and engaging diverse stakeholders, this document aims to guide efforts towards a more resilient future for our shared coastline.

Approximately 91% of the seafood products sold in the United States are imported, and roughly

half of those imports are produced by aquaculture.5 These seafood imports total 2.45 million

metric tons, 89,000-90,500 metric tons of which is comprised of molluscan shellfish (e.g. oysters,

mussels, clams, and scallops).6 These imports have contributed to a significant seafood trade

deficit, which ballooned to $14 billion in 2016.7 Increased domestic aquaculture production has 

the potential to reduce this reliance on seafood imports, which could result in an estimated

additional 50,000 full-time and part-time jobs8 if United States “offshore” aquaculture production

is doubled.9 Furthermore, it has been suggested by some as a way to reduce the carbon footprint

associated with imported seafood.10

While the potential for increased domestic molluscan shellfish marine aquaculture production11

has been the subject of high-level discussion at federal and state levels, it is not without policy

challenges. Development of commercial marine aquaculture in federal waters of the Exclusive

Economic Zone (EEZ)12 has been constrained for decades by an unclear regulatory process and 

by the technical challenges of operating in an offshore environment.13 These uncertainties have

resulted in limited commercial investment, which federal and state regulatory agencies,

academia, and the industry have partnered to address. An additional challenge faced by the

aquaculture industry is the potential for user conflict in the growing area, such as competition

for space between aquaculture facilities and commercial and recreational fishing,14 which can

arise both during the permitting and operations phases of shellfish aquaculture production.

Though a common problem in both state and federal waters, user conflicts are often more

pronounced in state waters due to the host of recreational (e.g., SCUBA diving and boating) and

commercial uses (e.g., fishing and shipping) that are more prevalent.15 Despite these challenges,

the aquaculture industry continues to explore the option of operating facilities in the federal

waters of the EEZ. One example is Catalina Sea Ranch (CSR), a farm based in Southern

California, that currently farms mussels in the federal waters of the EEZ.

particularly in urban ecosystems. The project site, Manzanita Canyon, is located in the heart of a

“disadvantaged” community in San Diego, California. In urban watersheds such as this, ecosystems

provide services disproportionate to their size, yet are also highly vulnerable to climate change hazards

because of the heavy reliance on services and the relatively degraded state. This two-year project

improved water quality and climate resilience of an urban ecosystem and an underserved community by

engaging 2,253 community members in stewardship activities; restoring 7.56 acres of native coastal

scrub ecosystem, including planting, maintaining and monitoring 1,536 natives; and removing 22 metric

tons (758 m3) of invasive plants and trash. Findings from this project formed the basis of the following

stewardship recommendations:

1. Community engagement was most effective when community-based leaders or organizations

were involved in the motivation and recruitment of volunteers. Further, local recruitment was

effective, with 64% of volunteer effort contributed by neighbors, and 59% of effort contributed

by youth (through clubs and schools.)

2. Trash cleanup efforts should be focused on areas of illegal dumping and abandoned homeless

camps, with added effort near storm drains during the rainy season. Solutions closer to the

source of these inputs are also needed, such as improved social and housing programs for the

homeless; stricter enforcement and education surrounding illegal dumping; expansion of free

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large-item curbside pickup and drop-off location services; improved clean street strategies (e.g.,

more efficient street sweeping, neighborhood-driven litter reduction and cleanup strategies);

and collaboration with businesses and industry to improve incentives for reducing use of

common trash items, especially plastics.

3. Establishment of native plants requires not only native plantings, but also invasive plant

removal, and slope stabilization measures (e.g., closing renegade trails, use of erosion control

barriers). Planting in diverse clusters that include nearby well-established plant species; and

watering, weeding and fencing, especially in times of drought, should decrease planting

mortality due to stress, competition and herbivory.

4. Ecosystem restoration takes time. After two years of restoration efforts, restored plant

communities and substrates were on a trajectory of resembling reference plots, but were still

significantly different. Continued maintenance such as weeding and watering should facilitate

system development as native plantings establish and grow, and increasingly confer benefits

such as provision of year-round complex habitat, reduction of fire fuel (annual plants), and

resistance and resilience of the community to fire and drought.

This project strengthened the climate resilience of this urban community and section of watershed

by alleviating common urban stresses, namely non-native plant cover and trash pollution, known to

increase the vulnerability of an area to climate change impacts, such as increased intensity and

frequency of fire, drought, and flooding that results from more intense but less frequent storms.

Removal of 138 m3 (13 metric tons) of trash from urban waterways improved channel flow thereby

reducing risk of flooding, and reduced risk of contamination on site and downstream. Removal of

620 m3 (8.62 metric tons) of invasive plant material reduced risk of wildfire, by reducing fire fuel

levels, and lessened competition with fire- and drought-resistant natives. Planting of 1,537 native

perennials, totaling 73 m3 of native plant biomass by the end of the project, increased the

ecosystem’s carbon storage capacity, and added the complex and stable habitat that is associated

with plants that have diverse morphologies, perennial life cycles, and evolved resistance to drought

and fire. Further, community engagement not only provided needed help, but also increased public

awareness of the value of and threats to local coastal ecosystems, and the ways in which everyday

actions, such as planting natives and picking up trash, can influence the health of our environment

now and into the future.

While many studies have established the importance of streamflow as a driver of fish population dynamics, few have examined relationships between survival of juvenile salmonids and flow-related variables in intermittent streams. With predictions for higher frequency of drought conditions due to climate change, and the associated increasing human demand for water during the dry season, understanding fish­­­–flow relationships is becoming increasingly important for the protection of sensitive aquatic species. To examine the effects of low streamflow on juvenile salmonids rearing in small intermittent streams, we estimated survival and collected environmental data in four coastal California watersheds from 2011 to 2013. We used an individual-based mark-recapture modeling approach to evaluate the influence of flow-related variables on oversummer survival of PIT-tagged juvenile Coho Salmon stocked into eight stream reaches. Survival was positively associated with streamflow magnitude, wetted volume, and dissolved oxygen, and negatively associated with days of disconnected surface flow (days of disconnection), and temperature. Days of disconnection best explained survival, though the relationship varied by geomorphic reach type. Survival was lower in alluvial reaches as compared to bedrock and clay reaches, and showed a faster rate of decline with increasing days of disconnection and drought condition. In all reaches, the onset of pool disconnection represented a turning point at which water quality, water quantity, and survival declined. For this reason, we suggest that days of disconnection (or the flow magnitude at which pools become disconnected) is a useful metric for identifying flow-impaired reaches, informing streamflow protection strategies, and prioritizing streamflow enhancement efforts designed to benefit sensitive salmonid populations in intermittent streams.

Ocean acidification (OA) increasingly threatens marine systems, and is especially harmful to calcifying organisms. One important question is whether OA will alter species interactions. Crustose coralline algae (CCA) provide space and chemical cues for larval settlement. CCA have shown strongly negative responses to OA in previous studies, including disruption of settlement cues to corals. In California, CCA provide cues for seven species of harvested, threatened, and endangered abalone. We exposed four common CCA genera and a crustose calcifying red algae, Peyssonnelia (collectively CCRA) from California to three pCO₂ levels ranging from 419–2,013 µatm for four months. We then evaluated abalone (Haliotis rufescens) settlement under ambient conditions among the CCRA and non-algal controls that had been previously exposed to the pCO₂ treatments. Abalone settlement and metamorphosis increased from 11% in the absence of CCRA to 45–69% when CCRA were present, with minor variation among CCRA genera. Though all CCRA genera reduced growth during exposure to increased pCO₂, abalone settlement was unaffected by prior CCRA exposure to increased pCO₂. Thus, we find no impacts of OA exposure history on CCRA provision of settlement cues. Additionally, there appears to be functional redundancy in genera of CCRA providing cues to abalone, which may further buffer OA effects.

This document provides scientific guidance to the California Department of Fish and Wildlife (CDFW) regarding the potential impacts of climate change on California fisheries and recommendations for building resilience to buffer climatic forces. At CDFW’s request, the California Ocean Protection Council (OPC) provided funding to the Ocean Science Trust (OST) to convene an OPC Science Advisory Team (OPC-SAT) Working Group with relevant ecological, social science, and governance expertise. This guidance was prepared by OST and the OPC-SAT Working Group in partnership with CDFW, in adherence with the requirements in the OPC Staff Recommendation: “California State Fisheries Management: Current Efforts and Future Needs.” This project was developed for consideration by the California Department of Fish and Wildlife (CDFW) to help inform the state’s process to amend the Marine Life Management Act (MLMA) Master Plan. Products from this project have been submitted to CDFW for review and may be integrated, in full or in part, into a draft Master Plan Amendment. In addition, given the broad potential ecological, social and economic impacts from climate change, we hope the document provides useful guidance for other government agencies and departments, funders, affected individuals and communities, and non-governmental organizations engaging in action on this issue. Additional information about the Master Plan amendment process, including key resources and opportunities for stakeholder engagement, is available at https://www.wildlife.ca.gov/Conservation/Marine/Master-Plan.

The intensity and frequency of climate-driven disturbances are increasing in coastal marine ecosystems. Understanding the factors that enhance or inhibit ecosystem resilience to climatic disturbance is essential. We surveyed 97 experts in six major coastal biogenic ecosystem types to identify “bright spots” of resilience in the face of climate change. We also evaluated literature that was recommended by the experts that addresses the responses of habitat-forming species to climatic disturbance. Resilience was commonly reported in the expert surveys (80% of experts). Resilience was observed in all ecosystem types and at multiple locations worldwide. The experts and literature cited remaining biogenic habitat, recruitment/connectivity, physical setting, and management of local-scale stressors as most important for resilience. These findings suggest that coastal ecosystems may still hold great potential to persist in the face of climate change and that local- to regional-scale management can help buffer global climatic impacts.