•ENM/SDM in marine systems predominates at local scales and in the North Atlantic Ocean.•Most studies use correlative approaches to answer ecological or biogeographic questions.•Most studied groups ...have been fish, molluscs, and marine mammals.•There is a lack of clarity regarding the definitions of ENMs versus SDMs.•A third dimension is required to add precision and utility to marine models.
In recent years, the use of ecological niche models (ENMs) and species distribution models (SDMs) to explore the patterns and processes behind observed distribution of species has experienced an explosive growth. Although the use of these methods has been less common and more recent in marine ecosystems than in a terrestrial context, they have shown significant increases in use and applications. Herein, we provide a systematic review of 328 articles on marine ENMs and SDMs published between 1990 and 2016, aiming to identify their main applications and the diversity of methodological frameworks in which they are developed, including spatial scale, geographic realm, taxonomic groups assessed, algorithms implemented, and data sources. Of the 328 studies, 48 % were at local scales, with a hotspot of research effort in the North Atlantic Ocean. Most studies were based on correlative approaches and were used to answer ecological or biogeographic questions about mechanisms underlying geographic ranges (64 %). A few attempted to evaluate impacts of climate change (19 %) or to develop strategies for conservation (11 %). Several correlative techniques have been used, but most common was the machine-learning approach Maxent (46 %) and statistical approaches such as generalized additive models GAMs (22 %) and generalized linear models, GLMs (14 %). The groups most studied were fish (23 %), molluscs (16 %), and marine mammals (14 %), the first two with commercial importance and the last important for conservation. We noted a lack of clarity regarding the definitions of ENMs versus SDMs, and a rather consistent failure to differentiate between them. This review exposed a need to know, reduce, and report error and uncertainty associated with species’ occurrence records and environmental data. In addition, particular to marine realms, a third dimension should be incorporated into the modelling process, referring to the vertical position of the species, which will improve the precision and utility of these models. So too is of paramount importance the consideration of temporal and spatial resolution of environmental layers to adequately represent the dynamic nature of marine ecosystems, especially in the case of highly mobile species.
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.
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.
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.
Useful indicators of anthropogenic impacts on the function and structure of marine communities are needed. Traditionally, changes in marine biodiversity have been evaluated using ecological indices ...such as species richness and evenness. However, these indices overlook potential ecological differences. Indeed, these differences are more accurately reflected using functional diversity, which is likely more representative of key ecosystem processes, including resilience and resistance. However, calculating functional diversity is complex due to a lack of available information on the natural history of many marine species. To address this problem, we used the information on Echinoidea and Asteroidea in the Mexican Pacific to examine the relationship between the Rao's quadratic entropy index (FDQ), a commonly used functional diversity index, and indicators of community and taxonomic structure: richness (S), abundance (N), Shannon-Wiener diversity (H′), Pielou evenness (J'), taxonomic distinctness (Δ*), and average taxonomic distinctness (Δ+). We generated a set of equations to determine if these commonly used indices could be used as proximal indicators of FDQ. We obtained good correlations between functional diversity and structural diversity, although the significant correlations were between FDQ and J' (r = 0.975) and H′ (r = 0.965). These two ecological indices are very good indirect indicators of the local functional diversity of Echinoidea and Asteroidea in the Mexican Pacific and can be used as simple, inexpensive, and powerful tools to assess the complex effects of human-induced or natural perturbations in rocky reef ecosystems.
•Diversity and evenness are useful predictors of functional diversity.•Functional diversity is more representative of ecosystem processes.•These indices are inexpensive tools for management and conservation.
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.
Antipathes galapagensis
, Deichmann (Smithson Misc Collect 9:1–18, 1941), has been the object of intensive fishing in the Eastern Tropical Pacific due to its large and arborescent colonies and dense ...forests. Despite its importance as a habitat-forming species, little information exists about its basic biology. Thus, the objective of this study is to describe its reproductive cycle. Samplings were performed in Espiritu Santo Archipelago (La Paz Bay, Gulf of California, Mexico) over 22 months. Histological analyses were conducted on 197 coral samples collected to assess their reproductive strategy from 2018 to 2019. For the first time, male and female gametogenic development stages are described for the species, determining the mean diameter and size range of oocytes and spermatocysts for each gametogenesis sub-stage. The black coral
A. galapagensis
is an external spawner, adopting a partial spawning strategy, showing evidence of sequential hermaphroditism, and this latter representing the first documentation for the order Antipatharia. The estimated colony sexual maturity height is 102 and 93 cm for females and males, respectively. Gametogenesis begins in June and reaches the reproductive peak in September–October, where the highest frequency is observed of mature females and males and partial spawning. The reproductive cycle shows a correlation with seawater surface temperature increase in the study area, which reaches its maximum from September–October. The results provide the first knowledge contribution to the species biology, essential for its protection and conservation management.
Antipathes galapagensis and Myriopathes panamensis are black coral species (Order Antipatharia) distributed in the Eastern Pacific from the Gulf of California to the coasts of Peru, at depths from ...-10 m to -200 m for A. galapagensis and to -50 m for M. panamensis. Antipatharians have great ecological importance as engineer species and major constituents of "coral forests," which are recognized as vulnerable marine ecosystems. Antipathes galapagensis has been a target of fisheries in several countries and has frequently been overexploited. Thus, the aim of this study was to compile a database of georeferenced records of A. galapagensis and M. panamensis, and use distribution data and environmental variables to construct habitat suitability models with Maxent software, in order to better understand black coral environmental requirements and potential distributions in the Eastern Tropical Pacific. The models showed good fit and performance (AUC > 0.9); key variables that drive the potential distribution of both species were chlorophyll a, nutrient concentration, and seawater temperature. The models did not predict occurrences beyond the recognized distribution range limits of the species; notwithstanding, they indicated that the Pacific coast of the Baja California Peninsula and the central and southern coasts of the Mexican Pacific have areas of high suitability for the presence of these corals. To our knowledge, no black coral records from these sites exist in the literature to date; thus, field validations are needed to verify the model predictions. With these results, it is possible to offer suggestions of new conservation sites for black corals based on the areas with the highest probability of occurrence of the species. Keywords: Maxent, cold-water corals, Antipatharia, habitat suitability, Eastern Tropical Pacific
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
ZnAl2O4 nanoparticles were synthesized employing a colloidal method. The oxide powders were obtained at 300 °C, and their crystalline phase was corroborated by X-ray diffraction. The composition and ...chemical structure of the ZnAl2O4 was carried out by X-ray and photoelectron spectroscopy (XPS). The optical properties were studied by UV-vis spectroscopy, confirming that the ZnAl2O4 nanoparticles had a direct transition with bandgap energy of 3.2 eV. The oxide’s microstructures were microbars of ~18.2 nm in size (on average), as analyzed by scanning (SEM) and transmission (TEM) electron microscopies. Dynamic and stationary gas detection tests were performed in controlled propane atmospheres, obtaining variations concerning the concentration of the test gas and the operating temperature. The optimum temperatures for detecting propane concentrations were 200 and 300 °C. In the static test results, the ZnAl2O4 showed increases in propane response since changes in the material’s electrical conductance were recorded (conductance = 1/electrical resistance, Ω). The increases were ~2.8 at 200 °C and ~7.8 at 300 °C. The yield shown by the ZnAl2O4 nanoparticles for detecting propane concentrations was optimal compared to other similar oxides categorized as potential gas sensors.
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.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
PDF
