Impact of substrate and the presence of adults on recruitment of the red sea urchin Strongylocentrotus franciscanus in Baja California

Several authors have studied the protection that adult red sea urchins (Strongylocentrotus franciscanus) offer their juveniles and have found that post-settlement mortality due to the absence of adults can diminish recruitment to adult populations. It is also well documented that adult sea urchin densities are low in overexploited populations, reducing the protection adults can offer juveniles. When adults are absent, habitat structure plays a key role in the protection of juveniles against predation. In this study we analyze the spatial variation in S. franciscanus recruitment and assess the impact of substrate availability (percentage of crevices) and adult sea urchin density on recruitment along the west coast of Baja California. Recruit and adult red sea urchin densities were estimated at 10 sites by scuba diving. Habitat structure was assessed by the analysis of digital video images. Temporal variation in red sea urchin recruitment as well as its relation to substrate availability and adult density were analyzed at two sites during three consecutive years. There were significant differences in recruit density among sites and substrate structure was the main factor that explained these differences. Adult densities did not explain recruitment differences among sites; however, the temporal analysis results showed that both substrate structure and adult densities were important in explaining recruit densities at both sites. The absence of a clear spatial pattern suggests that other factors such as harvesting and larval retention may explain the differences observed in the density of recruits among sites.

Evaluation of tuna fishing zones in the eastern Pacific using a multicriteria method

A multicriteria assessment of fishing zones was carried out using the utility function (U) technique, considering three management objectives (maximizing tuna yield, minimizing dolphin mortality, and minimizing bycatch) and seven different weights among them. The Mexican purse-seine tuna fishery in the eastern Pacific Ocean was used as case study, based on data obtained between 1998 and 2003 by the Mexican Tuna-Dolphin Program. The fishing zones were classified by trimester according to U, and 64% were identified as conflictive (U > 0.666 for some weights, but U < 0.333 for others); hence, two of every three trimestral quadrants require negotiation among the decision makers given the complex nature of the fishery. Quadrants with specific characteristics were identified in cases where, for instance, some particular sets explained the high bycatch values, or the targeting of bluefin tuna explained their classification as excellent. Even though the weights used provided a good proxy, in view of the great variability in space and time of the pelagic resources, actual preferences (weights) should be differentiated in space and time in order to be useful in the decision-making process. Particularly noteworthy is that wellstructured and efficient management schemes have already been implemented for two of the objectives (maximizing tuna yield and minimizing dolphin mortality), but not for the third (minimizing bycatch).

Integrating climate adaptation and transboundary management: Guidelines for designing climate-smart marine protected areas

Climate change poses an urgent threat to biodiversity that demands societal responses. The magnitude of this challenge is reflected in recent international commitments to protect 30% of the planet by 2030 while adapting to climate change. However, because climate change is global, interventions must transcend political boundaries. Here, using the California Bight as a case study, we provide 21 biophysical guidelines for designing climate-smart transboundary marine protected area (MPA) networks and conduct analyses to inform their application. We found that future climates and marine heatwaves could decrease ecological connectivity by 50% and hinder the recovery of vulnerable species in MPAs. To buffer the impacts of climate change, MPA coverage should be expanded, focusing on protecting critical nodes for the network and climate refugia, where impacts might be less severe. For shared ecoregions, these actions require international coordination. Our work provides the first comprehensive framework for integrating climate resilience for MPAs in transboundary ecoregions, which will support other nations’ aspirations. © 2023 The AuthorsOpen access articleThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

Harnessing cross-border resources to confront climate change

The US and Mexico share a common history in many areas, including language and culture. They face ecological changes due to the increased frequency and severity of droughts and rising energy demands; trends that entail economic costs for both nations and major implications for human wellbeing. We describe an ongoing effort by the Environment Working Group (EWG), created by The University of California's UC-Mexico initiative in 2015, to promote binational research, teaching, and outreach collaborations on the implications of climate change for Mexico and California. We synthesize current knowledge about the most pressing issues related to climate change in the US-Mexico border region and provide examples of cross-border discoveries and research initiatives, highlighting the need to move forward in six broad rubrics. This and similar binational cooperation efforts can lead to improved living standards, generate a collaborative mindset among participating universities, and create an international network to address urgent sustainability challenges affecting both countries

Integrating climate adaptation and transboundary management:Guidelines for designing climate-smart marine protected areas

Climate change poses an urgent threat to biodiversity that demands societal responses. The magnitude of this challenge is reflected in recent international commitments to protect 30% of the planet by 2030 while adapting to climate change. However, because climate change is global, interventions must transcend political boundaries. Here, using the California Bight as a case study, we provide 21 biophysical guidelines for designing climate-smart transboundary marine protected area (MPA) networks and conduct analyses to inform their application. We found that future climates and marine heatwaves could decrease ecological connectivity by 50% and hinder the recovery of vulnerable species in MPAs. To buffer the impacts of climate change, MPA coverage should be expanded, focusing on protecting critical nodes for the network and climate refugia, where impacts might be less severe. For shared ecoregions, these actions require international coordination. Our work provides the first comprehensive framework for integrating climate resilience for MPAs in transboundary ecoregions, which will support other nations’ aspirations.</p