California Sheephead
Newswise — (Santa Barbara, Calif.) – Escalating sea temperatures are engulfing the oceans, shattering records and generating troublesome circumstances for aquatic creatures. In contrast to land heatwaves, episodes of sudden ocean warming can persist for extended periods, spanning months or even years. Globally, these 'marine heatwaves' have resulted in widespread species fatalities and migrations, economic downturns, and habitat degradation. Recent findings indicate that even fishing-restricted zones in the ocean remain susceptible to these severe occurrences intensified by climate change.
A report released today in Global Change Biology, spearheaded by UC Santa Barbara researchers, discovered that although California's array of marine protected areas (MPAs) yield numerous social and ecological advantages, they lack resilience against the consequences of ocean warming. MPAs are designated oceanic regions where human activities, such as fishing, are restricted to safeguard and preserve marine ecosystems, habitats, species, and cultural resources. As part of a decade-long evaluation of California's MPA network conducted at UCSB's National Center for Ecological Analysis & Synthesis (NCEAS), the study revealed that marine heatwaves impact ecological communities irrespective of whether they are safeguarded within MPAs.
"MPAs in California and globally offer numerous advantages, including heightened fish abundance, biomass, and diversity," stated Joshua Smith, the lead researcher of the study during his tenure as a postdoctoral researcher at NCEAS. "However, they were not originally intended to mitigate the consequences of climate change or marine heatwaves."
Smith and a team of co-authors from various locations worldwide collaborated as part of an NCEAS working group specifically established to synthesize extensive long-term ecological monitoring data encompassing California's diverse marine habitats. The group, jointly led by Jenn Caselle, a researcher at UCSB's Marine Science Institute, and Kerry Nickols, a professor formerly affiliated with Cal State University Northridge and currently associated with the non-profit organization Ocean Visions, aimed to deliver actionable scientific findings to California's policymakers and natural resource managers as part of the statewide Decadal Evaluation of the MPA network. Their analysis encompassed the largest marine heatwave ever recorded, which unfolded in the Pacific Ocean and reached California from 2014 to 2016. This formidable marine heatwave resulted from a dual environmental impact – an unusual ocean warming event known as "The Blob," followed by a significant El Niño occurrence that extended the duration of elevated sea temperatures. The marine heatwave engulfed the West Coast, spanning from Alaska to Baja, and triggered a cascade of consequences, including disrupted food webs, depleted fisheries, and shifts in marine life populations, among other impacts.
With the rising frequency of climate-related disturbances, MPA managers worldwide are confronted with the pressing issue of whether MPAs can effectively mitigate the impacts of such events. Consequently, the scientific team from the working group embarked on a crucial inquiry: How did the ecological communities within California's protected areas respond to an extreme and prolonged heatwave? Did these communities undergo significant shifts, and if so, what were the nature of these shifts? Could they "bounce back" once the marine heatwave dissipated? Moreover, was it possible for marine protected areas to safeguard vulnerable populations or aid in the recovery process? These questions sought to shed light on the capacity of MPAs to provide resilience and support in the face of climate-related challenges.
In their quest for answers, the researchers synthesized more than ten years' worth of data gathered from 13 no-take MPAs situated in diverse ecosystems along the Central Coast of California. These MPAs encompassed rocky intertidal zones, kelp forests, as well as shallow and deep rocky reefs. The team focused on analyzing the populations of fish, invertebrates, and seaweed both within and outside these designated areas, utilizing data collected prior to, during, and after the occurrence of the heatwave. By examining these comprehensive datasets, the researchers aimed to gain insights into the dynamics and responses of various marine species and communities to the marine heatwave event.
Additionally, the researchers specifically emphasized two habitats, rocky intertidal zones and kelp forests, within a total of 28 MPAs spanning the entire statewide network. The objective was to assess whether these specific locations facilitated a specific type of climate resilience, namely the preservation of both population and community structure. By delving into the dynamics of these habitats across the extensive MPA network, the researchers aimed to gain insights into the potential of these areas to sustain the integrity and functioning of marine populations and ecological communities in the face of climate-related challenges.
"We utilized no-take MPAs as a means of comparison to determine whether the protected ecological communities exhibited better resilience to the marine heatwave compared to areas where fishing activities took place," explained Smith, who currently serves as an Ocean Conservation Research Fellow at the Monterey Bay Aquarium. By contrasting the outcomes between the MPAs and non-protected areas, the researchers aimed to assess the effectiveness of these conservation measures in mitigating the impacts of the marine heatwave on ecological communities.
The results are somewhat sobering, though not altogether unexpected.
Caselle noted, "The MPAs did not exhibit resistance or aid in the recovery of habitats or communities, regardless of the habitat type or taxonomic group." She further explained that in the face of the unprecedented marine heatwave, substantial and comparable changes occurred in both the MPAs and non-protected areas. The notable aspect of this study was the observation of similar outcomes across diverse habitats and taxonomic groups, encompassing deepwater and shallow reefs, as well as various marine organisms ranging from fishes to algae. This finding highlighted the widespread impact and magnitude of the marine heatwave on ecological communities, irrespective of protection status within MPAs.
According to Smith, the implications of these findings are that every corner of the ocean is vulnerable to the impacts of climate change. While MPAs have proven effective in fulfilling their designated objectives, the research indicates that relying solely on MPAs is inadequate to mitigate the effects of climate change. The study suggests that additional measures and strategies beyond MPAs are necessary to address the broader challenges posed by climate change and its consequences on marine ecosystems. These findings emphasize the urgency of comprehensive and holistic approaches to combat climate change and protect the ocean's delicate balance.
The critical question now revolves around the future outlook. As of the time of this study, which employed data until 2020, the ecological communities had not yet returned to their pre-heatwave state. The research revealed that these communities experienced significant shifts characterized by a notable decline in the relative proportion of cold-water species and an increase in warm-water species. A specific example highlighted in the paper is the rise in abundance of the señorita fish (Oxyjulis californica), a subtropical species with a preference for warm water that was previously uncommon in central California. The influence of such species on community dynamics was substantial. However, whether these species will persist in their new locations and how the overall ecological communities will evolve in the long term remain uncertain. Future observations and research are needed to understand the persistence and consequences of these ecological shifts.
Caselle emphasized the crucial importance of long-term monitoring of California's MPAs in light of the study's findings. She highlighted that certain monitoring time series have already exceeded 25 years, providing invaluable data for comprehending and preparing human communities for the ongoing changes in marine ecosystems. Sustained research efforts will enable the examination of whether future shifts in marine communities transpire at varying rates or towards different ecological states within MPAs compared to areas where fishing activities occur. Such investigations will contribute to a more comprehensive understanding of the dynamics and impacts of climate change on marine communities, facilitating informed decision-making and management strategies to mitigate future challenges.
Despite the limitations in their ability to withstand the impact of marine heatwaves, MPAs still offer valuable benefits, particularly in terms of studying the intricate effects of climate change in areas unaffected by fishing. By serving as areas with minimal human interference and regular monitoring, MPAs provide unique opportunities to investigate how marine ecosystems respond to changing conditions. These studies can potentially inform tailored management strategies to address climate change impacts effectively. Furthermore, as Smith emphasized, MPAs continue to protect ecological communities, even if they undergo changes due to heatwaves. Considering that marine heatwaves are projected to become more frequent and severe in the future, urgent climate action and nature-based solutions are necessary to bolster the health and resilience of our oceans. By embracing multiple pathways, including swift climate action and the implementation of nature-based solutions, we can enhance the ability of MPAs to cope with these challenges and protect marine ecosystems.
Kerry Nickols emphasizes the need for transparency and honesty regarding climate solutions in the face of the already evident and devastating impacts of climate change. It is crucial to acknowledge that as long as we continue to burn fossil fuels and contribute to global warming, marine ecosystems will remain vulnerable to risks, even if they are safeguarded from fishing activities. This statement underscores the inextricable link between climate change and the health of marine ecosystems, emphasizing the urgent need to address the root causes of climate change to effectively protect and preserve these delicate environments.
This paper serves as the initial installment in a series of articles spearheaded by the NCEAS working group. Subsequent publications will delve into various aspects related to the California MPA network. These forthcoming articles will explore topics such as human engagement within the MPA network, the impact of MPAs on fish populations and fisheries, and a comprehensive synthesis of MPAs that effectively balance the needs of both people and nature. Together, these subsequent studies aim to provide a comprehensive understanding of the dynamics, effectiveness, and potential improvements of MPAs in California, shedding light on the complex interactions between human activities, ecological conservation, and sustainable resource management.
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