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The Pacific oyster (Crassostrea gigas) is an important commercial species introduced to Mexico in the 1970s for aquaculture production. A purportedly infertile triploid variety of this species was authorized for farming in the El Vizcaino Biosphere Reserve (EVBR), to generate economic benefits for local residents while at the same time avoiding offsite propagation. Nevertheless, the presence of oysters at Ojo de Liebre lagoon, a core area of the reserve, has been observed. To test for the occurrence of C. gigas beyond its rearing areas, 240 oysters were collected from 10 sites in the lagoon and analyzed on the basis of its morphology and with the mitochondrial cytochrome oxidase subunit I; these approaches positively identified 95 and 70 C. gigas specimens respectively, corroborating the existence of individuals living outside the farming areas in the core zone of the reserve. Histological examinations discovered oysters with gonads in different stages of maturity (including spawning), verifying that the free-ranging specimens were reproductively active. We propose three hypotheses of how colonization of C. gigas took place at EVBR: the recruitment of larvae from unknown nearby populations, the inadvertent introduction of diploid organisms in the aquaculture facilities, and the possibility that triploid specimens growing in the local hatcheries have produced viable diploid gametes. Although C. gigas should be considered as an introduced species at the reserve, its population size is small, the specimens mostly settled on artificial substrata and do not cover large areas on the bottom, and there is no evidence of ecological damage or substitution of resident species. We suggest that the Pacific oyster is in the first stages of colonization in the EVBR, and that collaborative work of reserve managers and producers have the possibility to address the invasion and minimize potential negative effects on the local ecosystems, as well as possible dispersal to other areas. [ABSTRACT FROM AUTHOR]

More than 20 global marine extinctions and over 700 local extinctions have reportedly occurred during the past 500 years. However, available methods to determine how many of these species can be confidently declared true disappearances tend to be data-demanding, time-consuming, and not applicable to all taxonomic groups or scales of marine extinctions (global [G] and local [L]). We developed an integrated system to assess marine extinctions (ISAME) that can be applied to any taxonomic group at any geographic scale. We applied the ISAME method to 10 case studies to illustrate the possible ways in which the extinction status of marine species can be categorized as unverified, possibly extinct, or extinct. Of the 10 case studies we assessed, the ISAME method concludes that 6 should be categorized as unverified extinctions due to problems with species' identity and lack of reliable evidence supporting their disappearance (periwinkle—Littoraria flammea [G], houting—Coregonus oxyrinchus [G], long-spined urchin—Diadema antillarum [L], smalltooth sawfish—Pristis pectinata [L], and largetooth sawfish—P. pristis [L]). In contrast, ISAME classified the Guadalupe storm-petrel (Oceanodroma macrodactyla [G]) and the lost shark (Carcharhinus obsolerus [G]) as possibly extinct because the available evidence indicates that their extinction is plausible—while the largetooth sawfish [L] and Steller's sea cow (Hydrodamalis gigas [G]) were confirmed to be extinct. Determining whether a marine population or species is actually extinct or still extant is needed to guide conservation efforts and prevent further biodiversity losses. [ABSTRACT FROM AUTHOR]

A core challenge in ecology is identifying the factors that determine species distribution and functional diversity of species assemblages. Reef fish are the most diverse group of vertebrates, form taxonomically rich and functionally diverse communities and represent a key source of food for humans. We examine regional distribution patterns of reef fish species richness and functional diversity and investigate how these are determined by historical, biogeographic, energetic, and anthropogenic factors. We compiled data from 3,312 underwater visual censuses performed at 122 locations comprising rocky and coral reefs along the Eastern Tropical Pacific (ETP). We used generalized linear mixed‐effects models (GLMMs) implemented in a Bayesian framework to investigate whether distance from quaternary refugia, distance from mainland, shelf area, primary productivity, sea surface temperature (SST), human population gravity, and conservation status influence reef fish species richness and functional diversity in the ETP. Species richness and functional richness (FRic) peaked towards the center of the ETP and our null model suggests that FRic followed a spatial pattern that would be predicted by species richness. Additionally, functional evenness (FEve) was highest at higher latitudes whereas functional dispersion (FDis) was homogeneous throughout the ETP. Species richness was negatively influenced by shelf area and distance from mainland, but positively influenced by SST and conservation status. FEve was influenced by human population gravity and FDis by shelf area. Reef fish species richness and functional diversity in the ETP exhibited a strong division within the region mainly mediated by SST and human population gravity. Our results also suggest that dominant species within small shelf areas share more common traits than dominant species in large areas. This study uncovers previously unknown regional patterns of reef fish functional diversity and provides new insights into how historical, biogeographic, energetic, and anthropogenic factors influence complementary biodiversity facets. [ABSTRACT FROM AUTHOR]

Marine reserves generally permit ecotourism within their boundaries as a source of income for local communities, but the impacts of ecotourism on wildlife are still poorly understood. The lockdown resulting from the COVID‐19 pandemic in 2020 provided a unique opportunity to evaluate wildlife diversity in the absence of human activity. In a marine reserve in Mexico, we monitored fish assemblages before, during, and immediately after the lockdown to examine ecotourism impacts on fish assemblages. Our results show that fish density rose 2.5‐fold during the lockdown, suggesting that ecotourism activities alter fish behavior. We suggest that the presence of divers and noise pollution generated by recreational vessels are important disturbance factors. In the absence of human activity, however, some fish may be more bold (hide less often) or may return to the reserve after having retreated to more tranquil (deepwater) areas. We hope that our findings spur efforts to improve the health of marine reserves through the establishment of effective management strategies to mitigate ecotourism impacts. [ABSTRACT FROM AUTHOR]

The flexibility to associate with more than one symbiont may considerably expand a host's niche breadth. Coral animals and dinoflagellate micro-algae represent one of the most functionally integrated and widespread mutualisms between two eukaryotic partners. Symbiont identity greatly affects a coral's ability to cope with extremes in temperature and light. Over its broad distribution across the Eastern Pacific, the ecologically dominant branching coral, Pocillopora grandis, depends on mutualisms with the dinoflagellates Durusdinium glynnii and Cladocopium latusorum. Measurements of skeletal growth, calcification rates, total mass increase, calyx dimensions, reproductive output and response to thermal stress were used to assess the functional performance of these partner combinations. The results show both host–symbiont combinations displayed similar phenotypes; however, significant functional differences emerged when exposed to increased temperatures. Negligible physiological differences in colonies hosting the more thermally tolerant D. glynnii refute the prevailing view that these mutualisms have considerable growth tradeoffs. Well beyond the Eastern Pacific, pocilloporid colonies with D. glynnii are found across the Pacific in warm, environmentally variable, near shore lagoonal habitats. While rising ocean temperatures threaten the persistence of contemporary coral reefs, lessons from the Eastern Pacific indicate that co-evolved thermally tolerant host–symbiont combinations are likely to expand ecologically and spread geographically to dominate reef ecosystems in the future. [ABSTRACT FROM AUTHOR]

Understanding how emergent ecological assemblages have diverged from natural states is fundamental in predicting future functioning and services of ecosystems. Coral reefs are of particular concern due to their high susceptibility to anthropogenic stressors. Yet, little is known about their pre‐disturbance ranges of natural states, and most reports of decline are based on a limited number of sites and high levels of uncertainty. Here, we used a novel approach to estimate the physical functionality of reefs across marine ecoregions based on habitat suitability and morpho‐functional traits for coral species. We calibrated ecological niche models for 49 reef‐building corals of the Greater Caribbean based on occurrence records and environmental predictors, which we combined with species‐specific functional coefficients derived from morpho‐functional traits reflecting their contribution to the reef three‐dimensional structure to estimate the reef functional potential (RFP). We then assessed the degree of divergence of western Caribbean reefs by comparing our physical functionality estimates against recent field data evaluations. We found spatial variability in RFP across the Caribbean, with the highest mean value in the western Caribbean and the lowest in areas with marginal environmental conditions. Hotspots of RFP exist along the coast of Belize and the southeast of Cuba. Overall, 84% of sites along the western Caribbean showed a substantial reduction in their physical functioning, with the highest reductions occurring within hotspots, implying that reefs displaying the greatest changes have high initial RFP. We conclude that combining niche models with species morpho‐functional traits is a valuable and promising approach to estimate the large‐scale functional potential of communities and the degree of change in the absence of ecological baselines. These findings have important implications and could be used to guide efforts to preserve coral reefs functionality and define priority conservation areas in the Caribbean. [ABSTRACT FROM AUTHOR]

Marine biodiversity can be surveyed using underwater visual censuses and recently with eDNA metabarcoding. Although a promising tool, eDNA studies have shown contrasting results related to its detection scale and the number of species identified compared to other survey methods. Also, its accuracy relies on complete reference databases used for taxonomic assignment and, as other survey methods, species detection may show false‐negative and false‐positive errors. Here, we compared results from underwater visual censuses and simultaneous eDNA metabarcoding fish surveys in terms of observed species and community composition. We also assess the effect of a custom reference database in the taxonomic assignment, and evaluate occupancy, capture and detection probabilities, as well as error rates of eDNA survey data. We amplified a 12S rRNA fish barcode from 24 sampling sites in the gulf of California. More species were detected with eDNA metabarcoding than with UVC. Because each survey method largely detected different sets of species, the combined approach doubled the number of species registered. Both survey methods recovered a known biodiversity gradient and a biogeographic break, but eDNA captured diversity over a broader geographic and bathymetric scale. Furthermore, the use of a modest‐sized custom reference database significantly increased taxonomic assignment. In a subset of species, occupancy models revealed eDNA surveys provided similar or higher detection probabilities compared to UVC. The occupancy value of each species had a large influence on eDNA detectability, and in the false positive and negative error. Overall, these results highlight the potential of eDNA metabarcoding in complementing other established ecological methods for studies of marine fishes. [ABSTRACT FROM AUTHOR]

Aim: Mesophotic ecosystems, found at the limit of light penetration in the ocean, are rich in biodiversity and harbour unique ecological communities. However, they remain among the least studied habitat zones on earth due to the high costs and technological limitations. Here, we characterize mesophotic communities in two marine reserves across a range of habitat types, depths and temperatures using submersible technologies, with the goal of understanding the processes that structure these communities across biogeographical regions. Location: The Bay of La Paz and the Revillagigedo Archipelago, Mexico. Taxa: Fish and algal species. Methods: We used a small and inexpensive remotely operated vehicle (ROV) to conduct roving‐swim surveys of major habitat types in depths from 12 to 94 m. With the resulting binary data on the presence of fish species, we used generalized linear mixed models and canonical correspondence analysis to determine whether biogenic habitat, depth and/or temperature best explained species richness and community structure across reef and non‐reef substrate. Results: We identified 72 species or genera, including new depth records for nine fish species and a new geographical record for one fish species. Our surveys included large undocumented rhodolith beds (free‐living coralline algae) and mesophotic algal communities, in addition to diverse communities of soft corals and sponges. Fish species richness was positively associated with rocky substrate and warmer water, and reef fish communities differed significantly by depth, temperature and biogenic habitat. Main conclusion: Our results highlight the importance of biogenic habitat in structuring communities across gradients of depth and temperature. We also demonstrate the effectiveness of a small and economical ROV for conducting mesophotic surveys in remote regions. Our methods and results provide a framework that can be used to greatly increase the biogeographical and taxonomic scope of mesophotic research, especially for readily identifiable taxa such as fish. [ABSTRACT FROM AUTHOR]

Understanding the effects and benefits provided by the design and management of Marine Protected Areas (MPAs) is crucial for developing cost‐effective management actions. We characterized the management and design of no-take zone (NTZ) networks of eight Mexican Caribbean MPAs. To determine protection effectiveness, we followed a two-step approach. First, we evaluated the effect of the level of protection (NTZ, partial and unprotected areas), habitat structure and local human threats on four fish community metrics: total biomass, commercial fish biomass, mean trophic level and commercial fish mean size. If the protection afforded by the NTZ was significant, a second model was developed to evaluate design and management effectiveness. Total biomass, commercial fish biomass and mean trophic level were correlated significantly and positively with no-take protection; and, partially protected areas showed a significant and positive correlation with commercial fish biomass and mean trophic level. MPA age was the only significant and positive design and management characteristic that explained the variation in commercial fish biomass. This might be in part due to the suboptimal design of the MPA network that has mostly resulted from economic and social opportunities with little consideration for ecological guidelines and management capacities. Our findings suggest that to increase reef fish protection it would be necessary to include reef habitats with high coral cover and structural complexity inside NTZs. However, the effectiveness of an MPA network not only requires ecological considerations but also factors that include compliance, enforcement and true community participation to achieve greater benefits. Policymakers must ensure adequate design and management of MPAs in order to improve the effectiveness of marine resource protection, promoting both sustainable use and long-term biodiversity conservation. [ABSTRACT FROM AUTHOR]

Multi-use marine protected areas (MUMPAs) are a commonly applied tool for marine conservation in developing countries, particularly where large no-take reserves are not socially or politically feasible. Although MUMPAs have produced benefits around the world, the persistence of moderate fishing pressure reduces the likelihood of achieving the primary objective of these areas, which is the conservation of ecosystems. In this study we used traditional and functional metrics to evaluate how fish assemblages changed through time in a MUMPA, including shifts in species responses and in ecological processes. We conducted visual censuses of fishes at Espíritu Santo Island, México (MUMPA; N= 320; 240 N, 1100 W) from 2005 to 2017 to assess fish richness, size-distribution and density. Three functional indices were calculated using six traits (size, mobility, period of activity, aggregation, position in water column and diet): functional richness (volume occupied by species), dispersion (complementarity between species) and originality (inverse of functional redundancy). We compared fish diversity among three management zone types (sustainable fishing, traditional fishing and no-take zones), through a 13-year period, assessing which species increased or decreased in occurrence, density, and biomass, and how indices respond over time. Despite a general increase in biomass and stability in density and originality, we detected a reduction in fish biodiversity in the form of declines in species and functional richness, which could imply the risk of local extinction and decrease in certain ecosystem processes. In addition, changes in functional dispersion showed that some functions are losing representation through time. Although no single cause is apparent, such factors as competitive interactions, habitat loss and persistence of fishing pressure potentially explain these decreases. The rise in biomass was associated with a general increase in the average size, rather than increased biomass of commercial species, as the latter remained stable during the study period. Expansion of no-take areas, enforcement of fishing regulations, and surveillance in core zones, should be implemented to reverse the decline in particular species and to promote conservation of fish functional diversity in this MUMPA. [ABSTRACT FROM AUTHOR]

Copyright of Western Birds is the property of Western Field Ornithologists and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Climate change, mismanaged resource extraction, and pollution are reshaping global marine ecosystems with direct consequences on human societies. Sustainable ocean development requires knowledge and data across disciplines, scales and knowledge types. Although several disciplines are generating large amounts of data on marine socio-ecological systems, such information is often underutilized due to fragmentation across institutions or stakeholders, limited standardization across scale, time or disciplines, and the fact that information is often not searchable within existing databases. Compiling metadata, the information which describes existing sets of data, is an effective tool that can address these challenges, particularly when metadata corresponding to multiple datasets can be combined to integrate, organize and classify multidisciplinary data. Here, using Mexico as a case study, we describe the compilation and analysis of a metadatabase of ocean knowledge that aims to improve access to information, facilitate multidisciplinary data sharing and integration, and foster collaboration among stakeholders. We also evaluate the knowledge trends and gaps for informing ocean management. Analysis of the metadatabase highlights that past and current research in Mexico focuses strongly on ecology and fisheries, with biological data more consistent over time and space compared to data on human dimensions. Regional imbalances in available information were also evident, with most available information corresponding to the Gulf of California, Campeche Bank and Caribbean and less available for the central and south Pacific and the western Gulf of Mexico. Despite existing knowledge gaps in Mexico and elsewhere, we argue that systematic efforts such as this can often reveal an abundance of information for decision-makers to develop policies that meet key commitments on ocean sustainability. Surmounting current cross-scale social and ecological challenges for sustainability requires transdisciplinary approaches. Metadatabases are critical tools to make efficient use of existing data, highlight and address strengths and deficiencies, and develop scenarios to inform policies for managing complex marine social-ecological systems. [ABSTRACT FROM AUTHOR]

Copyright of Revista Mexicana de Biodiversidad is the property of Universidad Nacional Autonoma de Mexico, Instituto de Biologia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

No-take marine reserves can be powerful management tools, but only if they are well designed and effectively managed. We review how ecological guidelines for improving marine reserve design can be adapted based on an area’s unique evolutionary, oceanic, and ecological characteristics in the Gulf of California, Mexico. We provide ecological guidelines to maximize benefits for fisheries management, biodiversity conservation and climate change adaptation. These guidelines include: representing 30% of each major habitat (and multiple examples of each) in marine reserves within each of three biogeographic subregions; protecting critical areas in the life cycle of focal species (spawning and nursery areas) and sites with unique biodiversity; and establishing reserves in areas where local threats can be managed effectively. Given that strong, asymmetric oceanic currents reverse direction twice a year, to maximize connectivity on an ecological time scale, reserves should be spaced less than 50-200 km apart depending on the planktonic larval duration of target species; and reserves should be located upstream of fishing sites, taking the reproductive timing of focal species in consideration. Reserves should be established for the long term, preferably permanently, since full recovery of all fisheries species is likely to take > 25 years. Reserve size should be based on movement patterns of focal species, although marine reserves > 10 km long are likely to protect ~ 80% of fish species. Since climate change will affect species’ geographic range, larval duration, growth, reproduction, abundance, and distribution of key recruitment habitats, these guidelines may require further modifications to maintain ecosystem function in the future. [ABSTRACT FROM AUTHOR]

The brown sea cucumber Isostichopus fuscus is the most important commercial holothurian in the eastern Pacific, and its high market value caused overfishing and sharp declines of its populations and catches in several Latin American countries. In Mexico, the fishery has been intense in the northern Gulf of California since the 1990s, and it is currently under strong regulation. To evaluate the current status of the organisms, we measured the size, weight and estimated the relative condition index (Kn) of 702 specimens sampled in 86 rocky reefs of that region in 2016, at depths from 3 to 22 m. Mean length ± SD was 22.32 ± 5.23 cm, lower than average in the northern Gulf, but nevertheless, the average weight was 420.61 ± 192.48 g, among the highest recorded in the eastern Pacific; this is presumably due to the high primary production of the region that favors the presence of well-nourished organisms. The weight (W)-length (L) relationship was W = 3.27 L1.56, and condition index ranged from 0.045 to 2.13 (mean Kn = 0.96 ± 0.29), a figure that did not differ to that reported along the Mexican Pacific. There were differences in the value of Kn among sites, being higher in areas that are subject to the low fishing effort. [ABSTRACT FROM AUTHOR]

The coral Porites sverdrupi is the only scleractinian endemic to the Gulf of California. Over the last 2 decades its populations have been restricted to 3 areas, La Paz Bay, Loreto Bay, and Concepción Bay. As this species faces a high risk of extinction, there is an urgent need for biological, ecological, and genetic information for the guidance of conservation efforts. This is the first study on genetic diversity and connectivity in the species. For this, we analyzed coral colonies from Loreto Bay and Concepción Bay. Our results show that there is high genetic diversity in P. sverdrupi at both sites, with significant genetic structure between them. This condition is caused by a combination of short pelagic larval duration, low dispersal potential between the populations, and local adaptation. Our results emphasize the need for more research in order to establish adequate conservation strategies. [ABSTRACT FROM AUTHOR]