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The Yucatán Peninsula, Mexico is a carbonate platform well-known for extensive karst networks of densely stratified aquifer ecosystems. This aquifer supports diverse anchialine fauna, including species of the globally distributed anchialine shrimp genus Typhlatya (Atyidae). Four species (T. campecheae, T. pearsei, T. dzilamensis and T. mitchelli) are endemic to the Peninsula, of which three are federally listed in Mexico. This first integrative evaluation (i.e., molecular, morphological, broad geographic and type locality sampling, and environmental data) of Yucatán Typhlatya reveals considerable species identity conflict in prior phylogenetic assessments, broad species ranges, syntopy within cave systems and five genetic lineages (of which two are new to science). Despite sampling from the type locality of endangered T. campecheae, specimens (and molecular data) were indistinguishable from vulnerable T. pearsei. Ancestral/divergence reconstructions support convergent evolution of a low-salinity ancestor for a post-Paleogene arc Yucatán + Cuba Typhlatya clade within the anchialine Atyidae clade. A secondary adaptation for the coastal-restricted euryhaline (2–37 psu), Typhlatya dzilamensis (unknown conservation status) was identified, while remaining species lineages were low-salinity (< 5 psu) adapted and found within the meteoric lens of inland and coastal caves. This study demonstrates the need for integrative/interdisciplinary approaches when conducting biodiversity assessments in complex and poorly studied aquifers. [ABSTRACT FROM AUTHOR]

The biodiversity and biogeographic affinity of benthic amphipods from the Yucatan continental shelf with the warm Northwest Atlantic ecoregions were analysed using species occurrence data from benthic marine habitats of the continental shelf (< 200 m). A comprehensive collection of distributional data (presence-only) was obtained from different sources and newly-sampled material and sorted according to 12 ecoregions from the Northwest Atlantic. Distribution of species richness, taxonomic distinctness, endemism, and spatial replacement was analysed across ecoregions. The faunal relationships among ecoregions were explored using a clustering analysis based on the Sørensen dissimilarity index, and a cladistic analysis of distributions and endemism based on parsimony. Results from the Yucatan shelf showed a representative species pool from the highly diverse Northwest Atlantic amphipod fauna (202 spp.), with intermediate levels of endemism and taxonomic distinctness. Results from dissimilarity and parsimony showed two groups of amphipod assemblages consistent with two of the main biogeographic provinces in the Northwest Atlantic: Carolinian and Caribbean. The incorporation of the Yucatan shelf species assemblage, as an ecoregion into the used classification scheme, had implications on the amphipods biogeographic affinity identification. The Yucatan ecoregion led to a latitudinal spatial replacement of amphipod species across ecoregions and provinces, revealing that the Yucatan ecoregion has a higher biogeographic affinity with tropical ecoregions of the Caribbean province. The spatial replacement of amphipods suggests that the Southern Gulf of Mexico ecoregion has a higher affinity with warm-temperate ecoregions of the Carolinian province and is proposed as a transitional zone between the identified provinces. [ABSTRACT FROM AUTHOR]

Marine amphipods are gaining attention in aquaculture as a natural live food alternative to traditional preys such as brine shrimps (Artemia spp.). The use of Artemia is convenient for the culture of many marine species, but often problematic for some others, such as seahorses and other marine ornamental species. Unlike Artemia, marine amphipods are consumed by fish in their natural environment and show biochemical profiles that better match the nutritional requirements of marine fish, particularly of polyunsaturated fatty acids (PUFA), including eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids. Despite their potentially easy culture, there are no established culture techniques and a deeper knowledge on the reproductive biology, nutritional profiles and culture methodologies is still needed to potentiate the optimization of mass production. The present study assessed, for the first time, the aquaculture potential of Parhyale hawaiensis and Elasmopus pectenicrus, two cosmopolitan marine gammarids (as per traditional schemes of classification) that naturally proliferate in the wild and in aquaculture facilities. For that purpose, aspects of the population and reproductive biology of the species were characterized and then a series of laboratoryscale experiments were conducted to determine amphipod productivity, the time needed to reach sexual maturity by hatchlings (generation time), cannibalism degree, the effects of sex ratio on fecundity and the effects of diet (shrimp diet, plant-based diet and commercial fish diet) on fecundity and juvenile growth. P. hawaiensis, unlike E. pectenicrus, was easily maintained and propagated in laboratory conditions. P. hawaiensis showed a higher total length (9.3±1.3 mm), wet weight (14.4±6.2 mg), dry weight (10.5 ± 4.4 mg), females/males sex ratio (2.24), fecundity (12.8 ± 5.7 embryos per female), and gross energy content (16.71 ± 0.67 kJ g-1) compared to E. pectenicrus (7.9 ± 1.2 mm total length; 8.4 ± 4.3 mg wet weight; 5.7 ± 3.2 mg dry weight; 1.34 females/males sex ratio; 6.5 ± 3.9 embryos per female; 12.86 ± 0.82 kJ g-1 gross energy content). P. hawaiensis juvenile growth showed a small, but significant, reduction by the use of a plant-based diet compared to a commercial shrimp and fish diet; however, fecundity was not affected, supporting the possible use of inexpensive diets to mass produce amphipods as live or frozen food. Possible limitations of P. hawaiensis could be their quite long generation times (50.9±5.8 days) and relatively low fecundity levels (12.8 ± 5.7 embryos per female). With an observed productivity rate of 0.36 ± 0.08 juveniles per amphipod couple per day, P. hawaiensis could become a specialty feed for species that cannot easily transition to a formulated diet such as seahorses and other highly priced marine ornamental species. [ABSTRACT FROM AUTHOR]

This study is the first inventory of ascidians from shallow waters (0-25 m) of coastal and reef habitats in the southern Gulf of Mexico where ascidian diversity is poorly known. Sampled environments in 14 locations (38 sites) with 134 samples collected from 2015 to 2017 included coral reefs, coastal lagoons, mangroves, seagrass, ports, and artificial platforms. The 31 identified species comprise 19 genera and 13 families. Ten species are newly reported in the Gulf of Mexico: Ascidia panamensis Bonnet & Rocha, 2011; Ecteinascidia styeloides (Traustedt, 1882); Cystodytes roseolus Hartmeyer, 1912; Eudistoma aff. amanitum Paiva & Rocha, 2018; Eudistoma recifense Millar, 1977; Euherdmania fasciculata Monniot, 1983; Euherdmania aff. vitrea Millar, 1961; Polycarpa cartilaginea (Sluiter, 1885); Botrylloides magnicoecum (Hartmeyer, 1912) and Didemnum granulatum Tokioka, 1954. Two new species will be described separately (Clavelina sp. and Pyura sp.). This study provides the first records for 26 species ascidians for the region as well as describes increased distributions of ten Atlantic species. Thus, our data provide a starting point for future ecological, experimental and taxonomic studies of ascidians of the Gulf of Mexico. [ABSTRACT FROM AUTHOR]

This study represents the first comprehensive chiton study from Alacranes Reef, the largest reef system in the Gulf of Mexico. Nine chiton species were found in seven localities within the area, in the intertidal and subtidal to 12 m depth. SEM examination of C. janeirensis, A. hemphilli, T. schrammi and C. floridanus, showed variations in the sculpture and radular teeth morphology when compared to specimens of the same species from Florida Keys, Bahamas and Puerto Rico. The distribution ranges of T. schrammi, L. liozonis and S. floridana are extended into the south-western area of the Gulf of Mexico. Altogether, combining previous literature and the present survey, reports eleven chiton species which have now been recorded within the Alacranes reef area. [ABSTRACT FROM AUTHOR]

We present 52 new geographic location records for the peracarid crustacean Antromysis cenotensis Creaser, 1936, endemic in cenotes of the Yucatan Peninsula, Mexico. This species is currently considered threatened and, therefore, is protected by Mexican law. These results arise from several expeditions carried out between 2017 and 2020 in 75 locations within the cenote-ring, the interior, and coastal plains of the peninsula. A comprehensive literature review provided 84 geographic location records since the species was described in 1936. A map with 136 geographic location records that better describe the current species distribution is also included. With this information, plus some notes on the ecology of the species, a comprehensive literature and data review, and a brief analysis regarding the possible factors associated with the confirmed absence of the species in some locations in the state of Yucatan, we provide a brief and condensed summary of the actual knowledge on this particular species. The data in Darwin Core format can be retrieved in Zenodo. [ABSTRACT FROM AUTHOR]

Here, we show a spatially explicit assessment of the vulnerability of benthic communities from the Yucatan Continental Shelf (YCS) to multiple pressures: fishing activities, shipping traffic, storms and hurricanes, and marine acidification. The vulnerability index was obtained by combining benthic biological traits with exposure and sensitivity and recovery capacity; this was then represented in a spatially explicit model. Moreover, we estimated a cumulative vulnerability index using three different scenarios that were based on 1) equal weight for each vulnerability layer to each stressor, 2) results of expert consultation and 3) a linear reduction in the weight of the pressures. By comparing scenarios, the synergistic and antagonistic effects of the multiple stressors were determined. The main results showed that, independent of the considered scenario, approximately 90% of the YCS presented moderate to high vulnerability to cumulative pressures, while areas with high recovery and high potential impact on a particular stressor showed low or moderate vulnerability to the pressures. Meanwhile, areas classified as having medium impact levels and low recovery capacities of benthic fauna showed moderate to high vulnerability to the same threats. Our findings also showed that ship traffic and marine acidification were the threats that contributed to the greatest vulnerability. The paired comparison of scenarios allows for the identification of areas with higher probabilities of synergistic effects. No antagonistic effects were detected. Overall, our results constitute the first effort to understand the ecological status of the benthic communities of the YCS and their potential vulnerability to the multiple pressures they face. • Vulnerability assessment to multiple pressures identify areas with high potential impact. • Marine traffic and ocean acidification are the main threats for the benthos. • The inclusion of benthic recovery traits improves the vulnerability assessment. • Synergistic and antagonistic impacts can be identified using pressures weighting scenarios. [ABSTRACT FROM AUTHOR]

The coast of the Yucatan Peninsula (Mexico) has undergone numerous changes over the last century as a result of population growth, shifts in land use, establishment of industries, and storm impacts. To understand how the mollusc fauna responded to these changes over time, paleoecological studies were conducted to compare historical and modern data, and to reveal information on past environmental conditions. We analyzed mollusc assemblages in sediment cores from Río Lagartos coastal lagoon, which span the last ∼70 years. Mollusc assemblages in the sediment cores were compared to a modern inventory of Mollusca fauna, which was compiled to assess species distributions associated with multiple environmental variables. Mollusc assemblages from the sediment cores (17,089 specimens), which represent 19 bivalve and 43 gastropod species, and modern inventory datasets possess the same ubiquitous species and the same feeding guilds, i.e., groups that exploit the same food resources. Nearly twice as many species were identified in the sediment cores as in the modern inventory. This finding probably reflects the fact that the mollusc community changed through time at the core sites in response to shifting environmental conditions. Nevertheless, we encountered a number of taxa in the modern survey samples, which were absent from the sediment cores. This was probably a consequence of the limited spatial coverage of the cores and small diameter of the core barrels, which precluded sampling of large taxa. We report differences in mollusc abundance and taxonomic composition in the cores across space and time, which may be related to salinity changes in the lagoon and modifications of the nearby terrestrial environment. • Mollusc identified in sediment cores from Río Lagartos coastal Lagoon increased the total number of taxa previously registred • The number of mollusc species in sediment cores is nearly double that from the present-day inventory of taxa. • Stratigraphic shifts in sedimented molluscs assemblages revealed past environmental changes. • Mollusc species composition in sediment cores revealed differences across space and through time. [ABSTRACT FROM AUTHOR]

Amphipod species collected during three oceanographic campaigns (2010–2012) were analyzed to describe their spatiotemporal community distribution trends and their relationships with bottom water and sediment variables. The results show that the species richness (117 spp.) did not reach its maximum value according to the species accumulation curve (up to 187 spp.). Multivariate analyses and constrained ordinations techniques detected three main amphipod assemblages along the longitudinal gradient (i.e., Western Caribbean, Mid-Yucatan, and West-Yucatan) and during two temporal hydrographic scenarios (i.e., upwelling in 2010–2011 and non-upwelling in 2012). In 2010–2011, low values in species richness and abundance from the Western Caribbean and eastern Mid-Yucatan assemblages were associated with relatively low bottom-water temperatures from the upwelling systems. In 2012, the absence of upwelling and the occurrence of a warm-core anticyclonic eddy seemed to cause an increase in species richness and abundance in the three assemblages. The hydrographic variability and sediment characteristics are suggested as the major environmental drivers that shapes the soft-bottom amphipod community structure and diversity in the Yucatan continental shelf. • Three species assemblages were identified along the longitudinal gradient. • Depth gradient influence the species richness, abundance, and species composition. • The upwelling systems influence the temporal variability of the species assemblages. • Hydrographic and sedimentary variability induces major changes in the distribution and diversity of amphipods. [ABSTRACT FROM AUTHOR]