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The genus Urotrygon comprises small‐ to medium‐sized endemic round rays on the American continent and has undergone several synonymization processes. Here, we used an integrative taxonomic approach, including meristic, morphometric, and mtDNA analyses, to resolve the particularly intricate relationship among Urotrygon munda Gill, 1863, Urotrygon chilensis (Günther, 1872), and Urotrygon asterias (Jordan & Gilbert, 1883). The latter species is currently a synonym of U. munda but is also considered the U. chilensis “northern morphotype.” These taxonomic entities have historically been confounded, mainly due to their phenotypical resemblance along their geographic distribution in the eastern Pacific. We assessed 78 specimens (43 “northern” and 30 “southern morphotypes” of U. chilensis, as well as 5 U. munda) using 19 external variables for taxonomic and morphometric analysis. Distinct meristic patterns, including pectoral and pelvic ceratotrichia, vertebrae number, and thorn distribution along the dorsal midline, were observed in the series‐type specimens of the three taxonomic entities. Our multivariate morphometric analyses consistently differentiated the three groups as distinct taxonomic entities, with an overall classification accuracy of 66.7%. The meristic results also provided reliable information distinguishing the three entities. Based on the nicotinamide adenine dinucleotide (NADH2) and cytochrome oxidase subunit I (COI) genes, our phylogenetic analysis were consistent with the morphometric and meristic data, supporting these three entities as distinct species having their own evolutionary lineages. Our comprehensive approach confidently demonstrated that the northern U. chilensis morphotype matched and corresponded to the description of the Starry round ray, U. asterias, confirming its taxonomic resurrection as a valid species distinct from U. chilensis and U. munda. The geographic distribution of U. asterias spans from the tropical west coast of Mexico (including the Gulf of California) to Costa Rica, revealing that microevolutionary processes have well‐defined population clades within this range. Furthermore, U. chilensis is unequivocally established as the sole Urotrygon species occurring south of the Guayaquil marine ecoregion. In addition, the public COI and NADH2 sequences available for Urotrygon hosted in the ad hoc online databases were found to be misidentified, emphasizing the need for rigorous taxonomic scrutiny in this group. Finally, our research underscores the significance of an integrative approach that combines morphometric, meristic, and molecular techniques with historical data to disentangle the complexities of closely related taxa. [ABSTRACT FROM AUTHOR]

We present a meta-analysis of mangrove litterfall across 58 sites in the American Pacific, exploring its variability among geoforms, ecoregions, and provinces. This study contributes to filling the information gap on litter-based primary productivity in American mangroves at the ecoregional level and directly examines the effects of geomorphological and biogeographic factors on mangrove productivity. The objective was to evaluate how geoform, ecoregion, and province factors, along with eight environmental variables, influence litterfall-based primary productivity. Each site was categorized according to its landform through the analysis of satellite images obtained from various sensors on the Google Earth Pro v. 7.3.6 platform. Additionally, it was categorized according to its ecoregion and province by analyzing the occurrence of the sites on biogeographic unit coverage in ArcMap 10.4.1. We then analyzed the effect of each factor and the efficiency of categorization using multivariate methods. Our results showed significant differences in litterfall among the geoforms, with estuaries exhibiting higher litterfall production (11.90 Mg ha−1 year−1) compared to lagoons (7.49 ± 4.13 Mg ha−1 year−1). Differences were also observed among provinces, with the highest average in the Tropical Eastern Pacific (11.19 ± 3.63 Mg ha−1 year−1) and the lowest in the Warm Temperate Northeast Pacific (7.34 ± 4.28 Mg ha−1 year−1). Allocation success analyses indicated that sites classified by dominant species and province were more predictable (>60.34%) for litterfall production. Additionally, the maximum temperature and the precipitation of the wettest month and the driest month explained 34.13% of the variability in mangrove litter-based primary productivity. We conclude that mangrove litterfall production is influenced by coastal geomorphic characteristics and biogeography, which are, in turn, affected by latitude-induced climate variation. [ABSTRACT FROM AUTHOR]

The dynamics shaping the El Niño‐Southern Oscillation's (ENSO) response to present and future climate change remain unclear, partly due to limited paleo‐ENSO records spanning past abrupt climate events. Here, we measure Mg/Ca ratios on individual foraminifera to reconstruct east Pacific subsurface temperature variability, a proxy for ENSO variability, across the last 25,000 years, including the millennial‐scale events of the last deglaciation. Combining these data with proxy system model output reveals divergent ENSO responses to Northern Hemisphere stadials: enhanced variability during Heinrich Stadial 1 (H1) and reduced variability during the Younger Dryas (YD), relative to the Holocene. H1 ENSO likely intensified through meltwater‐induced changes to ocean/atmospheric circulation, a response observed in models, but the lack of a similar response during the YD challenges model simulations. We suggest the tropical Pacific mean state during H1 primed ENSO for larger fluctuations under meltwater forcing, whereas the YD mean state likely buffered against it. Plain Language Summary: The El Niño‐Southern Oscillation (ENSO) is one of the planet's largest and most influential recurring climate patterns. The fluctuation between warm (El Niño) and cold events (La Niña) every several years has a substantial impact on global weather patterns that carry important socioeconomic consequences. How the frequency and severity of ENSO events may change in response to present and future climate change is largely uncertain, although lessons from past abrupt climate events can help inform our projections of future ENSO. To that end, we analyzed the chemical composition of small, individual zooplankton shells buried in marine sediments to reconstruct "snapshots" of subsurface temperature variability in the eastern Pacific, a feature closely linked to ENSO, over the last 25,000 years. During this time, two abrupt climate events induced by melting glacial ice ("Heinrich Stadial 1" and the "Younger Dryas") were characterized by different ENSO responses (stronger and weaker, respectively). We suggest that the average climate conditions in the tropical Pacific (temperature, wind strength, etc.) played an important role by either priming the ENSO system for disruption by meltwater (Heinrich Stadial 1) or buffering against it (Younger Dryas). Key Points: Single‐shell foraminiferal trace element ratios reveal a deglacial history of El Niño‐Southern Oscillation's (ENSO) variability from the eastern equatorial PacificMeltwater‐induced changes to ocean and atmospheric circulation likely amplified ENSO during Heinrich Stadial 1A similar amplification during the Younger Dryas is not observed, suggesting mean state may mediate millennial‐scale ENSO variability [ABSTRACT FROM AUTHOR]

The interaction between the tropical Pacific and Atlantic at the decadal timescale has received widespread attention. This study evaluates the simulation of the interdecadal interaction of the tropical Pacific and Atlantic in 39 Coupled Model Intercomparison Project Phase 6 (CMIP6) models. Most of CMIP6 models have a positive correlation with the observations. The high-skill models reproduce well the temporal evolution of the lead–lag correlation. However, the low-skill models cannot reproduce the observed relationship between tropical Pacific decadal variability (TPDV) and tropical Atlantic multidecadal variability (TAMV) relationship, always incorrectly simulating the observed negative correlation when TAMV leads greater than 3 years as a positive correlation. We additionally demonstrate that the intermodel spread in the TPDV–TAMV relationship when TAMV leads is primarily linked to the persistence of TPDV and the background sea surface temperature (SST) in the northern tropical Atlantic. A relatively lower background SST in the north tropical Atlantic suppresses local convection and the remote response to TAMV-related SST anomalies. Consequently, the low-level circulation anomalies in the tropical Pacific connected to TAMV in the low-skill models are not primarily dominated by the observed easterly anomalies. Our research highlights the importance of background SST in the simulation of interbasin interaction and the necessity for model selection before applying CMIP models in relevant studies. [ABSTRACT FROM AUTHOR]

Seagrasses are globally acknowledged as crucial habitats as they provide a variety of ecosystem services. Mexico's legislation protects most of these marine plants; however, the protection often fails in application. The Gulf of California, despite being a biodiversity hotspot, has scant data on seagrasses. Here, human activity and climate change increasingly threaten these coastal ecosystems, with conservation and research efforts lacking coordination at a regional level. Our manuscript aimed to review and standardize existing data on Gulf of California seagrass species, ensuring open access for data updates; pinpointing conservation deficiencies; and guiding future research. We have added new records to the official public data, but we were able to recapture only 25% of the seagrass locations meaning a potential reduction in their historical distribution of 45.8%. Even though Mexico's legislation protects some species of seagrasses, it protection often fails in the application. We identified that only 6.1% of the seagrass locations are within protected areas that recognize their presence in their management plans (e.g., the Balandra Flora and Fauna Protected Area and the Upper Gulf of California and Colorado River Delta Biosphere Reserve). At least 55.9% of seagrass records are associated with potentially damaging activities like pollution, coastal modification or biological resources use, while 23% are exposed to higher frequency of marine heatwaves. Given the importance of seagrass meadows under Mexican law and their internationally recognized ecological value, sharing current information and guiding research is essential. Our study seeks to galvanize renewed research initiatives and raise more awareness on the conservation of the Gulf of California's seagrasses. [ABSTRACT FROM AUTHOR]

The Eastern Pacific Equatorial region is an important fishing ground for China, and there is a close relationship between mesoscale eddies and the distribution of fishing grounds. In this study, a vector geometry method based on flow field was used to identify mesoscale eddies in the Eastern Pacific Equatorial region （85°W-125°W, 5°S-5°N） using 2012-2018 meteorological satellite remote sensing data and filtering out vortices with a lifespan longer than one week. The spatial distribution, radius range, lifecycle, migration path, and velocity of mesoscale eddies in this region were analyzed. The relationship between the eddy and the fishing ground distribution was also discussed. The results showed that the number of anticyclonic eddies in the Eastern Pacific Equatorial region was greater than that of cyclonic eddies. The eddy lifecycle was relatively short, with the majority lasting no more than one week. The eddy radius was mainly concentrated in the range of 250-310 km, and the migration velocity was mainly concentrated at 6-18 m/s, with a migration distance of 25-50 km. There were two regions, called as "tropical regions," near the 5°N and 5°S, which exhibited more frequent eddy activity, while near the equator, there were almost no eddies present. Additionally, some characteristics of the eddies （period and radius） showed obvious interannual variations. These findings provide a basis for analysis of fishing ground formation, temporal and spatial distribution, and the development of fishing forecasts in the Eastern Pacific Equatorial region. [ABSTRACT FROM AUTHOR]

This study examines the distribution of Wedge-tailed Shearwater Ardenna pacifica along the northwest coast of South America. The species is well known in tropical waters distant from the coast, but it also appears to be a regular visitor to shelf-break waters off Colombia and northern Ecuador; there is no evidence indicating a similar presence within the exclusive economic zone (EEZ) of Peru, where waters are colder. About 50% of Wedge-tailed Shearwater sightings are associated with dolphins and/or large fish. More than 90% of the nearshore South American records are of pale-phase individuals. [ABSTRACT FROM AUTHOR]

Nematoda is the fourth most diverse animal phylum and is widely distributed. Marine nematodes are generally the most speciose group of meiofauna, yet there are relatively few studies on the taxonomy and biodiversity of free living marine nematodes. Here we present a review of the existing scientific literature and data in international databases on marine nematodes of Costa Rica. Most of the papers currently available mentioned Nematoda as the most abundant phylum in terms of the number of individuals within sand samples, nonetheless, only three publications included taxonomic data such as the description of new species or new records. Most publications are for the Pacific coast and we found only one paper for the Caribbean coast of Costa Rica. Large sections of the coasts and almost all the Exclusive Economic Zone remain unexplored in terms of nematode diversity, abundance and ecological role. Ten species, five free-living and five parasitic species, have been reported from the coasts of Costa Rica. Several reports indicate the presence of nematodes without further identification. More effort should be dedicated to the taxonomic identification of nematodes since, in addition to being the most abundant group, they can also be used as biological indicators. [ABSTRACT FROM AUTHOR]

The distribution range of the jumbo squid (Dosidicus gigas) has increased over the past few decades; it is now found in the entire Eastern Pacific Ocean and is considered an important species in the small and large fisheries of Chile, Perú, Ecuador, Costa Rica and Mexico but not in the Pacific region of Colombia. Three night-fishing campaigns were conducted over a year in the coastal Baudó-San Juan environmental unit, adjacent to the Bajo Baudó Encanto de Manglares Regional Integrated Management District in Chocó, at three locations 20 km, 35 km, and 45 km from the coastline to establish the availability and viability of jumbo squid as an alternative to the target species of artisanal fisheries in the Colombian Pacific. Night fishing sets were conducted at 60 m and 200 m depth at each sampling station to assess some of the biological parameters of the jumbo squid population (mantle length-ML, weight, growth and size at sexual maturity). Most catches were obtained in February and March. Growth was isometric, the average catch size was 24.3 cm ML, size at sexual maturity (L50) was 23.25 cm ML, estimated maximum size (L∞) was 39.9 cm ML, the growth constant (K) was 0.83, and mortality due to experimental fishing was 26 cm ML. According to our results, the jumbo squid fishery in the Colombian Pacific artisanal fishery would be viable during the first months of the year. [ABSTRACT FROM AUTHOR]

Isostichopus badionotus (Selenka, 1867) is distributed in the Atlantic Ocean. It has been recognized as a species with highly variable intraspecific coloration. To clarify taxonomic confusion and show the characters for correct identification of this valuable species, mitochondrial DNA (16S and COI), color patterns, external and internal morphology, ossicles, and habitat were examined in specimens from museum collections and from original sampling. As part of the revision, I. fuscus (Ludwig, 1875) from the Eastern Pacific Ocean and I. macroparentheses (Clark, 1922) from the Caribbean Sea, the only other two species currently recognized in the genus Isostichopus, were included. It was concluded that I. fuscus and I. macroparentheses are distinct and valid species, and that I. badionotus consists of two species: I. badionotus and I. maculatus (Greeff, 1882), previously synonymized as I. baqdionotus by Clark (1922). Isostichopus maculatus includes two subspecies, the nominal I. maculatus maculatus (Greeff, 1882) and I. maculatus phoenius (Clark, 1922), described as Stichopus badionotus var. phoenius Clark, 1922. Isostichopus maculatus maculatus, distributed in the East Atlantic, is very similar to I. maculatus phoenius, but differs in DNA characters, color pattern, and the size and shape of the tables in the dorsal papillae. Isostichopus maculatus phoenius, widely distributed in the Caribbean Sea and the Gulf of Mexico, is sympatric with I. badionotus, has similar ossicles but is clearly distinguished by its DNA sequences, color patterns, and habitat preferences. For the first time, ossicles from internal organs are described for Isostichopus, enhancing original species descriptions. Distribution maps, habitat, biology, conservation status, and a taxonomic key for distinguishing these species to aid their fishery management and aquaculture are presented.

In the American Museum of Natural History, New York, there is an old specimen labelled as “Holodromia harrisonwilliamsi Boone, MS name” that was collected from Cocos Island in 1925. This name has never been published. An examination of the specimen shows that it is a juvenile specimen of Homolodromia robertsi Garth, 1973, a species described from Peru, which has since been reported from Chile and off the coast of Ecuador. This paper reports on the specimen Homolodromia robertsi Garth found in Costa Rica for the first time, a discovery that extends the known range of this species northwards.

In the American Museum of Natural History, New York, there is an old specimen labelled as "Holodromia harrisonwilliamsi Boone, MS name" that was collected from Cocos Island in 1925. This name has never been published. An examination of the specimen shows that it is a juvenile specimen of Homolodromia robertsi Garth, 1973, a species described from Peru, which has since been reported from Chile and off the coast of Ecuador. This paper reports on the specimen Homolodromia robertsi Garth found in Costa Rica for the first time, a discovery that extends the known range of this species northwards. [ABSTRACT FROM AUTHOR]

While some previous studies examined the contribution of Eastern Pacific (EP) hurricanes toward precipitation in the arid Southwest US (SWUS), their potential to influence wildfires in that region has not been explored. Here we show, using observations and simulations from the Energy Exascale Earth System Model (E3SM), that recurving EP hurricanes modulate the wildfire environment in the SWUS by increasing precipitation and soil moisture, and reducing the vapor pressure deficit. This is especially the case during late season months of September–October when the likelihood of storms to recurve and make landfall increases. Further, analysis of burnt area observations reveals that for the months of September–October, recurving EP hurricanes may significantly reduce the prevalence of wildfires in the SWUS. Finally, E3SM simulations indicate that late season EP hurricanes have been on the decline, with important implications for wildfires in the SWUS. Plain Language Summary: A majority of Eastern Pacific (EP) hurricanes form and traverse westwards away from the North American coastline. Therefore, compared to tropical cyclones in some other basins, EP hurricanes have historically received less attention. However, some previous studies have shown that recurving EP hurricanes can contribute significantly to precipitation in the arid Southwest US (SWUS) region. Here, we build on these studies and demonstrate that recurving EP hurricanes significantly modulate the SWUS wildfire environment. During years with recurving EP hurricanes, the precipitation and soil moisture are enhanced, and the vapor pressure deficit is reduced, over the SWUS region. Therefore, during late season months of September–October, when recurving EP hurricanes occur, they make the environment less favorable for wildfires in the SWUS region. With climate models showing a long‐term decline in recurving EP hurricanes and the precipitation associated with them over the SWUS region, our study has substantial implications for autumn wildfires of that region. Key Points: Eastern Pacific (EP) hurricanes that recurve tend to enhance precipitation and reduce vapor pressure deficit in the Southwest US regionDuring September–October, recurving EP hurricanes may make the environment less favorable for wildfires in the Southwest USClimate model simulations suggest that Southwest US precipitation associated with recurving EP hurricanes has decreased [ABSTRACT FROM AUTHOR]

Aim: The poleward range expansion of tropical species, and range contraction of temperate species (known as tropicalisation) has mainly been studied from an ecological perspective, with little research on its genetic consequences. Here, we used distributional and genetic data to document the consequences of tropicalisation in rocky shore gastropods and assess more broadly the future implications of tropicalisation on phylogeographic patterns. Location: Nineteen sampling sites along >3000 km of the eastern Pacific rocky intertidal zone, from the tip of the Baja California Peninsula to southern California. Taxon: Temperate gastropods: Lottia conus, L. strigatella, Fissurella volcano and Tegula gallina. Tropical gastropods: Fissurella rubropicta, Nerita funiculata and N. scabricosta. Methods: We determine historical and modern distributions of tropical and temperate species by combining historical records with current field surveys. Using a section of the cytochrome oxidase subunit I gene, we utilised comparative phylogeography, analysis of molecular variance, FST pairwise comparison, mismatch distributions of haplotype differences and neutrality tests to detect genetic signatures of tropicalisation and to better understand its consequences. Results: We identified range contractions in two temperate species and range expansion in all three tropical species. We detected genetic signatures of range expansion in the tropical species through unimodal distributions of pairwise haplotype differences and strongly negative values for the Fu and Li D and F* statistics. We found population subdivision and phylogeographic breaks in three temperate species, although the geographic location of the breaks differed among species. Main Conclusions: Genetic signatures and field surveys indicate recent range expansions in tropical species, supporting tropicalisation along the studied coastline. Conversely, we found phylogeographic breaks in temperate species, suggesting that tropicalisation may cause genetic erosion of evolutionary distinct lineages with range‐contraction. The different locations of the phylogeographic breaks among temperate species suggests that some barriers are species specific. [ABSTRACT FROM AUTHOR]

A new labrid fish species, Halichoeres sanchezi n. sp., is described from eight specimens collected in the Revillagigedo Archipelago in the tropical eastern Pacific Ocean, off the coast of Mexico. The new species belongs to the Halichoeres melanotis species complex that is found throughout the region, differing by 2.4% in the mtDNA cytochrome c oxidase I sequence from its nearest relative, H. melanotis from Panama, and 2.9% from Halichoeres salmofasciatus from Cocos Island, off Costa Rica. The complex is distinguished from others in the region by having a black spot on the opercular flap and a prominent black area on the caudal fin of males. The juveniles and initial phase of the new species closely resemble those of H. salmofasciatus and Halichoeres malpelo from Malpelo Island of Colombia, differing in having an oblong black spot with a yellow dorsal margin on the mid-dorsal fin of initial-phase adults as well as on juveniles. In contrast, the terminal-phase male color pattern is distinct from other relatives, being vermilion to orangish brown with dark scale outlines, a white patch on the upper abdomen, and a prominent black band covering the posterior caudal peduncle and base of the caudal fin. The new species adds to the list of endemic fish species for the isolated archipelago and is an interesting case of island endemism in the region. The discovery was made during the joint 2022 collecting expedition to the archipelago, which featured a pioneering collaborative approach to an inventory of an island ichthyofauna, specifically including expert underwater photographers systematically documenting specimens in situ, before hand-collection, and then photographed fresh, tissue-sampled, and subsequently vouchered in museum collections. [ABSTRACT FROM AUTHOR]

The starfish Luidia magnifica (Asteroidea: Paxillosida: Luidiidae) is a multiradiate starfish that occurs throughout the Indo-Pacific. Since the description of L. magnifica in 1906 by Fisher, very few observations of this species have been documented. We present new shallow-water records for L. magnifica in the Tropical Eastern Pacific obtained between 2017 and 2021. We collected a total of 15 specimens of L. magnifica in the bay of Manzanillo, Colima, in the central nearshore Mexican Pacific. We provide morphological description of specimens collected and additional ecological data. We used molecular techniques to verify species identification. This record represents a considerable expansion of the known distribution range of L. magnifica and provides the first evidence of the presence of this species in the Tropical Eastern Pacific. The presence of L. magnifica larvae from the Caribbean coast of Panama was also identified from DNA sequencing of larvae left unindentified in previous reports. This result indicates that it is possible that the L. magnifica also occurs in the Carribbean. Because observations of the starfish in the Mexican Pacific have been recent, the presence of larvae in the Caribbean could be a recent introduction through the Panama Canal from the Eastern Pacific to the Western Atlantic. [ABSTRACT FROM AUTHOR]

In the Tropical Eastern Pacific dolphinfish (TEP) Corypahena hippurus is part of commercial, recreational, and artisanal fisheries and is also caught incidentally by the tuna purse-seine and longline fisheries. Defining the existence of differenced populations in exploited species for being considered independent management units is crucial for conservation plans. However, there is a great uncertainty about the species population genetic structure across the TEP. To investigate it and to identify possible management units for conservation purposes this study was carried out, based on two SNPs datasets of 3867 and 3220 SNPs for young of the year (YOY) and adult individuals, respectively, obtained through NGS protocols. Sampling covered the species' range distribution in the Tropical Eastern Pacific and was structured into YOY and adult individuals in order to discard the effects of migrating individuals into sampled locations. Our results revealed slight but significant differences among locations occupying the latitudinal limits of the species distribution at transitional areas between tropical and subtropical waters. These areas are characterized by strong seasonal variations in sea surface temperature and limit the prevalence of populations in these extremes. Genetic differences also seem to be related to spatial separation of locations as the northernmost (Los Cabos) and southernmost (Peru) locations including a set of oceanic samples, showed the highest levels of genetic differentiation. Whereas were detected barriers to gene flow among spatially separated locations for YOY individuals probably related to site fidelity, clear limitations to gene flow between Mexico and Central America locations were observed probably related to oceanic circulation in the area. Design management strategies in countries where the dolphinfish is explored is of primary interest to preserve genetic resources. It is necessary to define the existence of genetic differences of populations for species that are highly dependent on environmental factors limiting its distributional range as is the case of the dolphinfish. [ABSTRACT FROM AUTHOR]

Haminoea are herbivorous, coastal snails occurring in temperate and tropical waters of the Atlantic and Eastern Pacific oceans, with one species present in temperate South Africa (Indian Ocean). The genus is taxonomically difficult as several available nominal species were introduced based on shell descriptions alone, or described based on subtle differences in morpho‐anatomical features, without a phylogenetic molecular framework. Fifteen species are currently accepted as valid in recent scientific literature and field guides (eight Eastern Atlantic, one temperate Indian Ocean, four Western Atlantic and three Eastern Pacific). Here we generate the first complete phylogeny (Bayesian and Maximum Likelihood) of this genus based on multilocus molecular data (COI, 12S rRNA, 16S rRNA, 28S rRNA) using a taxon set accumulated over a period of 15 years, coupled with species delimitation analyses methods (ABGD, ASAP, bPTP) and morpho‐anatomical studies. The goal of this study is to provide insights into the taxonomy, phylogenetic relationships and geographical distributions of species while generating a framework for future systematic reviews of the genus, as well as to study speciation and historical biogeography. Our results rendered four possible hypotheses of species diversity: with 14, 15, 19 and 20 candidate species and point to the fact that several taxa presently regarded as valid might be conspecific (e.g. H. orteai–H. templadoi–H. exigua; and H. alfredensis–H. antillarum–H. orbignyana), while highlighting the existence of a complex of four or five species often identified as H. elegans. Pervasive nomenclatural problems in the genus, including with the type species H. hydatis, are highlighted and discussed. [ABSTRACT FROM AUTHOR]

Marine heatwaves (MHWs) have been recognized as a serious threat to marine life, yet, most studies so far have focused on the surface only. Here, we investigate the vertical dimension and propagation of surface MHWs in the Eastern Pacific (EP) using results from a high‐resolution hindcast simulation (1979–2019), performed with the Regional Ocean Modeling System. We detect MHWs using a seasonally varying percentile threshold on a fixed baseline and track their vertical propagation across the upper 500 m. We find that nearly a third (∼29%) of the MHWs extend beyond the surface mixed layer depth (MLD). On average, these deep‐reaching MHWs (dMHWs) extend to 110 m below the MLD and last five times longer than MHWs that are confined to the mixed layer (184 vs. 36 days). The dMHWs can cause stronger temperature anomalies at depth than at the surface (maximum intensity of 5.0 vs. 1.9°C). This general subsurface MHW intensification even holds when scaling the temperatures with the respective local variability. A clustering of dMHWs reveals that 41% of them are block‐like, that is, continually remain in contact with the sea surface, 24% propagate downward, 20% propagate upward, while 15% appear at the surface multiple times. Although the water column MHW duration, intensity and severity are only moderately correlated with their corresponding surface‐based MHW characteristics, dMHWs have the potential to be detected from the surface. Our study can help to augment the remote sensing‐based monitoring of upper ocean exposure to MHWs. Plain Language Summary: Periods of extremely warm water temperatures, referred to as marine heatwaves (MHWs), pose a serious threat to marine life. While many studies have analyzed MHW properties at the sea surface, little is known about their subsurface nature. We here use a new approach to define MHWs throughout the water column and study the vertical structure and propagation behavior of MHWs in the Eastern Pacific based on a high‐resolution numerical hindcast simulation (1979–2019). We find that nearly a third of MHWs that are discernible at the sea surface reach below the layer of well‐mixed waters near the sea surface, the so‐called mixed layer (ML). These deep‐reaching MHWs (dMHWs) last on average longer than ML confined MHWs (184 vs. 36 days) and are marked by larger temperature threshold exceedances (maximum intensity of 5.0 vs. 1.9°C). We furthermore identify four distinct vertical propagation patterns associated with the dMHWs: 41% continually affect the sea surface, 24% propagate downwards, 20% propagate upward, while 15% appear at the surface multiple times. Overall, these analyses show that MHWs can affect the water column to a larger degree than diagnosed based on the sea surface only. Key Points: About a third of marine heatwaves (MHW) in the Eastern Pacific extend below the mixed layer. Ten percent of MHWs extend on average deeper than 150 m59% of deep‐reaching MHWs (dMHWs) are partly invisible at the surface, as they either deepen, shoal or exhibit multi‐surfacing behaviorAs initial tests indicate that the surface‐based detection of dMHWs seems feasible, dMHWs might be detectable using remote sensing data [ABSTRACT FROM AUTHOR]

Abstract The dynamics shaping the El Niño‐Southern Oscillation's (ENSO) response to present and future climate change remain unclear, partly due to limited paleo‐ENSO records spanning past abrupt climate events. Here, we measure Mg/Ca ratios on individual foraminifera to reconstruct east Pacific subsurface temperature variability, a proxy for ENSO variability, across the last 25,000 years, including the millennial‐scale events of the last deglaciation. Combining these data with proxy system model output reveals divergent ENSO responses to Northern Hemisphere stadials: enhanced variability during Heinrich Stadial 1 (H1) and reduced variability during the Younger Dryas (YD), relative to the Holocene. H1 ENSO likely intensified through meltwater‐induced changes to ocean/atmospheric circulation, a response observed in models, but the lack of a similar response during the YD challenges model simulations. We suggest the tropical Pacific mean state during H1 primed ENSO for larger fluctuations under meltwater forcing, whereas the YD mean state likely buffered against it.

Seagrasses are globally acknowledged as crucial habitats as they provide a variety of ecosystem services. Mexico’s legislation protects most of these marine plants; however, the protection often fails in application. The Gulf of California, despite being a biodiversity hotspot, has scant data on seagrasses. Here, human activity and climate change increasingly threaten these coastal ecosystems, with conservation and research efforts lacking coordination at a regional level. Our manuscript aimed to review and standardize existing data on Gulf of California seagrass species, ensuring open access for data updates; pinpointing conservation deficiencies; and guiding future research. We have added new records to the official public data, but we were able to recapture only 25% of the seagrass locations meaning a potential reduction in their historical distribution of 45.8%. Even though Mexico’s legislation protects some species of seagrasses, it protection often fails in the application. We identified that only 6.1% of the seagrass locations are within protected areas that recognize their presence in their management plans (e.g., the Balandra Flora and Fauna Protected Area and the Upper Gulf of California and Colorado River Delta Biosphere Reserve). At least 55.9% of seagrass records are associated with potentially damaging activities like pollution, coastal modification or biological resources use, while 23% are exposed to higher frequency of marine heatwaves. Given the importance of seagrass meadows under Mexican law and their internationally recognized ecological value, sharing current information and guiding research is essential. Our study seeks to galvanize renewed research initiatives and raise more awareness on the conservation of the Gulf of California’s seagrasses.

We present a meta-analysis of mangrove litterfall across 58 sites in the American Pacific, exploring its variability among geoforms, ecoregions, and provinces. This study contributes to filling the information gap on litter-based primary productivity in American mangroves at the ecoregional level and directly examines the effects of geomorphological and biogeographic factors on mangrove productivity. The objective was to evaluate how geoform, ecoregion, and province factors, along with eight environmental variables, influence litterfall-based primary productivity. Each site was categorized according to its landform through the analysis of satellite images obtained from various sensors on the Google Earth Pro v. 7.3.6 platform. Additionally, it was categorized according to its ecoregion and province by analyzing the occurrence of the sites on biogeographic unit coverage in ArcMap 10.4.1. We then analyzed the effect of each factor and the efficiency of categorization using multivariate methods. Our results showed significant differences in litterfall among the geoforms, with estuaries exhibiting higher litterfall production (11.90 Mg ha−1 year−1) compared to lagoons (7.49 ± 4.13 Mg ha−1 year−1). Differences were also observed among provinces, with the highest average in the Tropical Eastern Pacific (11.19 ± 3.63 Mg ha−1 year−1) and the lowest in the Warm Temperate Northeast Pacific (7.34 ± 4.28 Mg ha−1 year−1). Allocation success analyses indicated that sites classified by dominant species and province were more predictable (>60.34%) for litterfall production. Additionally, the maximum temperature and the precipitation of the wettest month and the driest month explained 34.13% of the variability in mangrove litter-based primary productivity. We conclude that mangrove litterfall production is influenced by coastal geomorphic characteristics and biogeography, which are, in turn, affected by latitude-induced climate variation.

The Revillagigedo Archipelago, located in the Eastern Pacific Ocean, stands out for its unique biological richness and endemism. These islands remained uninhabited until the second half of the twentieth century, allowing a better conservation status than on other oceanic islands. However, the continuous introduction of potentially invasive alien plant species, and the lack of adequate control or eradication actions, jeopardize the conservation and restoration of these islands' fragile ecosystems. We present the most complete vascular plant species inventory and an updated list of alien plant species of the Revillagigedo Archipelago, which was compiled through an extensive review of national and international plant collections and other sources. Our 272 species list includes 106 alien plant species (39.3%; 104 in Socorro, and 16 in Clarion): 67 (24.8%) are naturalized, 14 (5.2%) are casual aliens, and 25 (9.3%) subsist under cultivation. The documented alien species belong to 73 families. Annual and perennial herbs are the prevailing life forms in the alien flora, while naturalized species are primarily native to North America. The number of introduced species has increased significantly since the islands became inhabited. Many of the recently introduced species pose a major invasion risk like on other islands of the world. [ABSTRACT FROM AUTHOR]

Abstract While some previous studies examined the contribution of Eastern Pacific (EP) hurricanes toward precipitation in the arid Southwest US (SWUS), their potential to influence wildfires in that region has not been explored. Here we show, using observations and simulations from the Energy Exascale Earth System Model (E3SM), that recurving EP hurricanes modulate the wildfire environment in the SWUS by increasing precipitation and soil moisture, and reducing the vapor pressure deficit. This is especially the case during late season months of September–October when the likelihood of storms to recurve and make landfall increases. Further, analysis of burnt area observations reveals that for the months of September–October, recurving EP hurricanes may significantly reduce the prevalence of wildfires in the SWUS. Finally, E3SM simulations indicate that late season EP hurricanes have been on the decline, with important implications for wildfires in the SWUS.

A new labrid fish species, Halichoeres sanchezi n. sp., is described from eight specimens collected in the Revillagigedo Archipelago in the tropical eastern Pacific Ocean, off the coast of Mexico. The new species belongs to the Halichoeres melanotis species complex that is found throughout the region, differing by 2.4% in the mtDNA cytochrome c oxidase I sequence from its nearest relative, H. melanotis from Panama, and 2.9% from Halichoeres salmofasciatus from Cocos Island, off Costa Rica. The complex is distinguished from others in the region by having a black spot on the opercular flap and a prominent black area on the caudal fin of males. The juveniles and initial phase of the new species closely resemble those of H. salmofasciatus and Halichoeres malpelo from Malpelo Island of Colombia, differing in having an oblong black spot with a yellow dorsal margin on the mid-dorsal fin of initial-phase adults as well as on juveniles. In contrast, the terminal-phase male color pattern is distinct from other relatives, being vermilion to orangish brown with dark scale outlines, a white patch on the upper abdomen, and a prominent black band covering the posterior caudal peduncle and base of the caudal fin. The new species adds to the list of endemic fish species for the isolated archipelago and is an interesting case of island endemism in the region. The discovery was made during the joint 2022 collecting expedition to the archipelago, which featured a pioneering collaborative approach to an inventory of an island ichthyofauna, specifically including expert underwater photographers systematically documenting specimens in situ, before hand-collection, and then photographed fresh, tissue-sampled, and subsequently vouchered in museum collections.

In the Tropical Eastern Pacific dolphinfish (TEP) Corypahena hippurus is part of commercial, recreational, and artisanal fisheries and is also caught incidentally by the tuna purse-seine and longline fisheries. Defining the existence of differenced populations in exploited species for being considered independent management units is crucial for conservation plans. However, there is a great uncertainty about the species population genetic structure across the TEP. To investigate it and to identify possible management units for conservation purposes this study was carried out, based on two SNPs datasets of 3867 and 3220 SNPs for young of the year (YOY) and adult individuals, respectively, obtained through NGS protocols. Sampling covered the species’ range distribution in the Tropical Eastern Pacific and was structured into YOY and adult individuals in order to discard the effects of migrating individuals into sampled locations. Our results revealed slight but significant differences among locations occupying the latitudinal limits of the species distribution at transitional areas between tropical and subtropical waters. These areas are characterized by strong seasonal variations in sea surface temperature and limit the prevalence of populations in these extremes. Genetic differences also seem to be related to spatial separation of locations as the northernmost (Los Cabos) and southernmost (Peru) locations including a set of oceanic samples, showed the highest levels of genetic differentiation. Whereas were detected barriers to gene flow among spatially separated locations for YOY individuals probably related to site fidelity, clear limitations to gene flow between Mexico and Central America locations were observed probably related to oceanic circulation in the area. Design management strategies in countries where the dolphinfish is explored is of primary interest to preserve genetic resources. It is necessary to define the existence of genetic differences of populations for species that are highly dependent on environmental factors limiting its distributional range as is the case of the dolphinfish.

The hawksbill sea turtle Eretmochelys imbricata is categorized as Critically Endangered on the IUCN Red List and its population has declined by over 80% in the last century. The Eastern Pacific population is one of the most threatened hawksbill populations globally. Western Mexico is the northern distribution limit for hawksbill sea turtles in the Eastern Pacific and recent research indicates that the Mexican Pacific portion of the population is a separate management unit because of the restricted movements of these turtles. Here we use the most complete database of sighting records in the north-west Pacific of Mexico to identify sites where hawksbill turtles are present. We also develop a conservation index to determine the conservation status of hawksbill turtle sites. Our results demonstrate the importance of this region for juveniles and the relevance of rocky reefs and mangrove estuaries as habitats for hawksbill turtles. We identified 52 sites with records of hawksbill turtles. Most of these sites (71%) are not protected; however, sites with high conservation value included islands and coastal sites along the Baja California peninsula that are established as marine protected areas. Reefs and mangrove estuaries relevant for hawksbill turtles are probably also significant fish nursery areas that are important for local fishing communities, creating opportunities for conservation strategies that combine science, local engagement and policy to benefit both local fishing communities and hawksbill sea turtle conservation.

Climate change impacts are projected to shift the distribution and abundance of global fisheries, affecting revenues and livelihoods worldwide (Barange et al., 2018; Lam et al., 2016). The creation of climate-resilient fisheries requires knowledge of how culturally and economically valuable species will be impacted by rising sea surface temperatures, ocean deoxygenation, and climatic variability. Two Western Pacific fisheries, the Pacific bluefin tuna (PBF; Thunnus orientalis) and Japanese anchovy (JA; Engraulis japonicus), may be particularly vulnerable to the impacts of climate change due to overfishing, sub-tropical spawning grounds, and declining prey availability (FAO, 2020; ISC, 2020). Chasing catch may become the new reality for commercial fleets around the world as PBF and JA inhabit new waters away from historic fishing grounds. In order to promote sustainable management of major global fisheries, policymakers must have the best tools and information available for how climate change will affect fisheries distribution and abundance through the 21st century.This study is aimed at improving the scientific basis for creating fisheries that are resilient to climate change by using climate change projections, species-specific life history traits, and ecological information to project potential fish stock distribution in response to changing coastal and oceanic conditions. Current projections focus on the use of suitable thermal habitat as a proxy for future species distribution and abundance (Morley et al., 2018). The aim of this study is to improve on these projections by evaluating the potential effects of changes in ocean mixing, nutrients, and other factors in addition to temperature as well as by incorporating information on how the target species (PBF and JA) are likely to respond to these changes using life history characteristics. Based on a decision tree provided by the Environmental Defense Fund, climate change is expected to impact every life stage of PBF and JA and centered around changes in sea surface temperature, ocean deoxygenation, and climatic variability. Future abundance of both species’ hinges on the survival of larval stages, recruitment success, and conservation measures to prevent the depletion of young age classes. Northward shifts in distribution are anticipated for both species into the next century, raising concerns about future international management. The entrance of new players into the PBF and JA fisheries may require international agreements based on the shift in distribution of each stock. International cooperation and adaptive management measures must be adopted by fisheries management entities to maintain productive fisheries that continue to generate social and economic benefits associated with PBF and JA.

Califrapana n. gen., is proposed for California late Oligocene to early Miocene muricids attributed previously to the possibly Paleocene to modern western Pacific and Indian oceans genus Rapana. Four fossil species have been assigned to Rapana in the eastern Pacific. One of these species, R. perrini Clark and Arnold (1923), should be placed in another genus, the other species Purpura vaquerosensis Arnold (1907), R. imperialis Hertlein and Jordan (1927), and R. serrai Wiedey (1928) are synonymized here with the morphologically variable species Califrapana vaquerosensis n. comb. We confirm C. vaquerosensis is an index fossil for the lower and middle “Vaqueros” California provincial molluscan stage of late Oligocene to early Miocene age in southern California and Bája California, México, although the lack of numerical dating and the misuse of lithostratigraphic and biostratigraphic names had made that difficult to determine. Califrapana is distinguishable from similar genera by 1) its heavier shell, 2) an aperture that is pointed at its anterior and posterior ends, 3) more numerous fine to coarse spiral cords on the ultimate whorl, 4) less numerous nodes at the top of the ultimate whorl, which are commonly larger and more pronounced, and 5) the siphonal fasciole, which is large and broad, with a large, open channel.

The distribution range of the jumbo squid (Dosidicus gigas) has increased over the past few decades; it is now found in the entire Eastern Pacific Ocean and is considered an important species in the small and large fisheries of Chile, Perú, Ecuador, Costa Rica and Mexico but not in the Pacific region of Colombia. Three night-fishing campaigns were conducted over a year in the coastal Baudó-San Juan environmental unit, adjacent to the Bajo Baudó Encanto de Manglares Regional Integrated Management District in Chocó, at three locations 20 km, 35 km, and 45 km from the coastline to establish the availability and viability of jumbo squid as an alternative to the target species of artisanal fisheries in the Colombian Pacific. Night fishing sets were conducted at 60 m and 200 m depth at each sampling station to assess some of the biological parameters of the jumbo squid population (mantle length-ML, weight, growth and size at sexual maturity). Most catches were obtained in February and March. Growth was isometric, the average catch size was 24.3 cm ML, size at sexual maturity (L50) was 23.25 cm ML, estimated maximum size (L∞) was 39.9 cm ML, the growth constant (K) was 0.83, and mortality due to experimental fishing was 26 cm ML. According to our results, the jumbo squid fishery in the Colombian Pacific artisanal fishery would be viable during the first months of the year.

Climate change research on sea turtles has focused on the impact of rising temperatures on sex ratios, while the thermal ecology of natural nesting grounds has received less attention. Many nesting beaches are highly affected by vegetation loss and urbanization which in turn may affect their thermal profile, particularly at beaches with dark volcanic sand. We studied the sand temperatures on two urban-developed volcanic sea turtle nesting beaches in Guatemala for two years, and their potential effect on the thermal ecology of sea turtle nests by using the olive ridley as model species. We hypothesized that local weather, type of cover at surface, and season (dry vs rainy) will have a pronounced effect on sand temperatures, potentially affecting the hatching success of sea turtles. Average sand temperatures at nesting beaches were almost always above the pivotal temperature (87% of days), and either close to or above the thermal maximum tolerance of sea turtle embryos over longer periods (78% of days). We found that higher air temperatures led to higher sand temperatures, and high relative humidity and precipitation led to lower sand temperatures. As expected, sand temperatures in plots covered by vegetation were lower (32.5 ± 2.8°C) than those without vegetation cover (33.1 ± 2.6°C). Plots close to concrete structures showed the highest sand temperatures (34.0 ± 3.2°C). Our results highlight the relevance of vegetation in buffering the effects of high sand temperatures, which will have profound implications for the resilience of olive ridleys to global warming.

The genus Metamysidopsis W. M. Tattersall is currently represented by two species in the eastern Pacific: M. elongata (Holmes, 1910) in California, U.S.A., and M. pacifica (Zimmer, 1918) in Peru and Panama. The distribution and some morphological details of both species are presented and discussed and a new species is described from the southern Gulf of California, western Mexico. Commonly used diagnostic characters for the species of Metamysidopsis are analysed based on data available in the literature. A diagnosis is provided for the three species occurring in the eastern Pacific and a key to the 10 currently known species of the genus is provided. [ABSTRACT FROM AUTHOR]

The hawksbill sea turtle Eretmochelys imbricata is categorized as Critically Endangered on the IUCN Red List and its population has declined by over 80% in the last century. The Eastern Pacific population is one of the most threatened hawksbill populations globally. Western Mexico is the northern distribution limit for hawksbill sea turtles in the Eastern Pacific and recent research indicates that the Mexican Pacific portion of the population is a separate management unit because of the restricted movements of these turtles. Here we use the most complete database of sighting records in the north-west Pacific of Mexico to identify sites where hawksbill turtles are present. We also develop a conservation index to determine the conservation status of hawksbill turtle sites. Our results demonstrate the importance of this region for juveniles and the relevance of rocky reefs and mangrove estuaries as habitats for hawksbill turtles. We identified 52 sites with records of hawksbill turtles. Most of these sites (71%) are not protected; however, sites with high conservation value included islands and coastal sites along the Baja California peninsula that are established as marine protected areas. Reefs and mangrove estuaries relevant for hawksbill turtles are probably also significant fish nursery areas that are important for local fishing communities, creating opportunities for conservation strategies that combine science, local engagement and policy to benefit both local fishing communities and hawksbill sea turtle conservation. [ABSTRACT FROM AUTHOR]

Abstract Background The first successful application of implanted archival tags on striped marlin showed great potential in obtaining long-term tracks for an improved understanding of movement ecology, which is important for informing fisheries management decisions. Ten tags were physically recovered from fish tagged in the Eastern Pacific between 2008 and 2016, but unfortunately due to the failure of the external sensor stalk which houses the light sensor, full records of daily fish position could not be attained. Results Depth-based geolocation, which exploits the diel swimming patterns of striped marlin, was applied to derive position estimates for archival tagged fish up to 7.7 years. Reconstructed tracks revealed tagged striped marlin remained in the Eastern Pacific throughout the tracked duration. Trans-equatorial movements were also documented for the first time for striped marlin in this region, as were extended occupancy of > 1 year in pelagic waters. Conclusions Striped marlin connected both coastal and offshore habitats with seasonal runs, likely in fulfillment of their life history requirements from foraging to reproduction. Circadian rhythms in billfish and other pelagic fishes are well-established, and could provide a viable, alternative means to position an individual in a low or no light environment, and situations with sub-optimal or limited bio-logging capabilities. Depth-based geolocation, however rudimentary, has revealed variability in striped marlin horizontal movements over the multi-year observation period, and offered a unique spatiotemporal perspective that was unavailable to scientists and fisheries managers until now.

Simple Summary: Understanding the mechanisms of predation dynamics in a sea turtle nesting beach is important in order to design a proper beach management plan and a valuable conservation strategy when working on sea turtle solitary nesting sites. We evaluated natural nest predation upon solitary Olive Ridley nesting events in Corozalito beach, a solitary and nascent arribada nesting beach on the Pacific in Costa Rica. Our results show a noticeable increase in predation rates close to 30% of nests predated throughout a 13-year study period. This could be an indicator of the increasing number of nesting events in this important nesting site. We suggest continuing to monitor the nesting activity at Corozalito, including the predation rates from other sea turtle species and mass nesting events to give a complete report of the threats that these species are facing in Corozalito and the impact on their population, combined with potential alternatives to manage predators' impact. In Corozalito beach, Costa Rica, Olive Ridley turtles (Lepidochelys olivacea) nest both solitarily and in arribadas. The predation of solitary nests was monitored from 2008 to 2021, recording date, time, sector of the beach, zone, status of nest (predated or partially predated) and predator when possible. We recorded 4450 predated nests in total (N = 30,148 nesting events); predation rates showed a fluctuating trend, with recent percentages reaching up to 30%, with four distinctive dips in 2010, 2014, 2016 and 2017. The spatial distribution of predated nests along the beach showed significant differences among the sectors regardless of the seasons (Friedman test, chi-squared = 14.778, df = 2, p-value = 0.000), with most predated nests (47.62%) occurring in the northern sectors of the beach. Predators were identified by their tracks and/or direct observations (N = 896, 24.08%). The most conspicuous predators identified were raccoons (55.69%) and black vultures (22.77%). As seen in Corozalito, predation rates have increased in recent years despite established conservation efforts. A comprehensive assessment of all threats towards the overall hatching success for clutches is needed, considering predation during mass nesting events, poaching and beach erosion, among other factors, to fully understand the nesting dynamics occurring in this beach. [ABSTRACT FROM AUTHOR]

Simple Summary: This paper presents important aspects of the life history of the black sea turtle (Chelonia mydas agassizii) population nesting on the beaches of Michoacan, Mexico. Information on morphometric and reproductive traits related to the life history of black sea turtles (body size, clutch size, egg size, fecundity, remigration interval, age at sexual maturity, and growth rate) was studied. An analysis of interannual variations in the life history traits of the species is also carried out, and the results obtained indicate that C. m. agassizii differs from the information reported for other populations of Chelonia mydas mydas distributed pantropically. Sea turtles present strategies that have allowed them to survive and reproduce. They spend most of their lives in the sea, except when they emerge as hatchlings from the nest and when the adult females return to nest. Those moments of their life cycle are vital for their reproductive success, conservation, and knowledge of their biology. This study reports the life history traits exhibited by female black sea turtles from Colola Beach, Mexico using morphometric and reproductive data obtained during 15 sampling seasons (1985–2000, n = 1500). The results indicate that nesting females have a mean body size of 85.7 cm and reach sexual maturity at 24 years old at a minimum size of 68 cm. Females deposit a mean of 69.3 eggs per clutch, and the mean fecundity was 196.4 eggs per female per season. The remigration intervals of 3 and 5 years were the most frequent registered. The life history traits found in the black sea turtle population present the lowest values reported with respect to studies conducted in the Atlantic and Indo-Pacific green turtle populations, which supports the hypothesis that this population is recovering, since morphometric and reproductive data represent young nesting turtles. [ABSTRACT FROM AUTHOR]

A new species of parasitic copepod, Lepeophtheirus mondacolasp. nov. (Siphonostomatoida; Caligidae), is described based on female and male specimens obtained from the shortjaw leatherjacket Oligoplites refulgens (Actinopterygii; Perciformes; Carangidae), captured in the southeastern Gulf of California off northwestern Mexico. The new species can be separated from its congeners by a combination of characters that includes: adult female with a subquadrate genital complex bearing slightly protruded posterolateral corners, two indistinct somites on the abdomen which, when combined together, is about two times longer than wide, a caudal ramus that is twice as long as it is wide, a postantennal process comprising a stout base and short claw, a dentiform process of the maxillule with two unequal tines, a maxilliped with a stout protopod and subchela, a sternal furca with a pair of bifurcated tines, a leg 3 exopod composed of 2 segments, five setae on the distal endopodal segment of leg 3 and a leg 4 exopod composed of three segments and armed with one long and two short apical spines on the distal exopodal segment; adult male with a suborbicular genital complex, an abdomen composed of one short and one long, indistinctly separated somites, a caudal ramus that is twice as long as it is wide, a stout postantennal process, a small triangular process at the base of the inner tine of the maxillulary dentiform process and a 3-segmented exopod on leg 4. Lepeophtheirus mondacolasp. nov. represents the first record of a species of Lepeophtheirus from a member of Oligoplites and the second caligid species reported from O. refulgens. [ABSTRACT FROM AUTHOR]

This work documents the first record of Anthias noeli Anderson & Baldwin, 2000 in Peru. Between 2016 and 2019, fifteen specimens were captured from the littoral of the Tumbes Department, located in the northernmost of Peru. Fresh photographs were taken of the specimens and meristic and morphometric analyses were conducted for species identification. Additionally, muscle tissue was extracted from five individuals to determine COI gene sequences. Phylogenetic analyses confirmed the specimens' identity as A. noeli, and the sequences were deposited in the public database BOLD Systems, representing the first deposited sequences for this species. This record expands the southern distribution of A. noeli.

Garden eels are known to form large single-species colonies on the sandy bottom of tropical nearshore areas throughout the world's oceans. Passing divers are met by areas full of almost identical snake-like creatures, with their upper bodies protruding out of their burrows, in which they retract quickly as intruders approach. However, during a 15-day expedition to the Gorgona Island, in the Pacific Ocean of Colombia, it was discovered that the garden eels might not be so identical after all in that area. Between August and September 2019, individuals of both Heteroconger klausewitzi and Heteroconger pellegrini were observed co-existing in the same colony, which was previously believed to be exclusively comprised of the species H. klausewitzi. Photo and video evidence of this co-existence was obtained, and three individuals of H. pellegrini were collected. A ratio of 95.9% of H. pellegrini and 4.1% of H. klausewitzi was obtained from counting individuals appearing in the obtained videos. Heteroconger klausewitzi was found at depths greater than 12 m, while H. pellegrini was present from 5 to 12 m depth. This appears to be the first report of the existence of multi-species colonies in garden eels, suggesting it is a new case of inter-species colony association in fishes, which opens a new window for ecological and social behavior studies. In addition to multi-species coexistence, this work also is the first report of H. pellegrini in South America (i.e., Colombia), extending its distribution range southward by approximately 550 km. [ABSTRACT FROM AUTHOR]

The bonnethead Sphyrna tiburo is a wide-spread, small species of coastal hammerhead shark with a long history of taxonomic uncertainty, including, according to some authors, disjoint subspecies in the western Atlantic and eastern Pacific oceans. The present study investigates the level of morphometric and genetic variation within the Sphyrna tiburo complex throughout most of its distributional range including the western Atlantic, the Gulf of Mexico, the Caribbean, and the eastern Pacific. A morphometric study, including a comparison of ampullary densities, and a molecular analysis of two mitochondrial genes, was performed. We analyzed variation in cephalofoil shape between and within lineages, based on landmarks and Fourier analysis of the silhouettes. All tests delineated discrete morphological groups, including differences of ampullae density for those lineages in which this information could be unambiguously assessed. Both morphometric and molecular analysis support the existence of three different evolutionarily significant units (two in the Atlantic: one northern and one south-central, and a third in the eastern Pacific) that deserve specific taxonomic status. We urge a deep taxonomic review of this complex to gather biological data on each lineage and develop adequate independent conservation strategies and actions to protect the various evolutionary units. [ABSTRACT FROM AUTHOR]

The Revillagigedo Archipelago, located in the Eastern Pacific Ocean, stands out for its unique biological richness and endemism. These islands remained uninhabited until the second half of the twentieth century, allowing a better conservation status than on other oceanic islands. However, the continuous introduction of potentially invasive alien plant species, and the lack of adequate control or eradication actions, jeopardize the conservation and restoration of these islands’ fragile ecosystems. We present the most complete vascular plant species inventory and an updated list of alien plant species of the Revillagigedo Archipelago, which was compiled through an extensive review of national and international plant collections and other sources. Our 272 species list includes 106 alien plant species (39.3%; 104 in Socorro, and 16 in Clarion): 67 (24.8%) are naturalized, 14 (5.2%) are casual aliens, and 25 (9.3%) subsist under cultivation. The documented alien species belong to 73 families. Annual and perennial herbs are the prevailing life forms in the alien flora, while naturalized species are primarily native to North America. The number of introduced species has increased significantly since the islands became inhabited. Many of the recently introduced species pose a major invasion risk like on other islands of the world.

Deep-sea chemosynthesis-based ecosystems support unique biological communities, but human impacts are an increasing threat. Understanding the life-history traits of species from deep-sea chemosynthesis-based ecosystems can help to develop adequate management strategies, as these can have impacts on ecological responses to changes in the environment. Here we examined the occurrence of sexual dimorphism in the yeti crab Kiwa puravida, an endemic species from the Costa Rican Pacific margin that aggregates at active methane seeps and depends on chemosynthetic bacteria for nutrition. The two morphological features examined included the claws, suspected to be under sexual selection and used for defense, and the carpus of the second pereopod not suspected to be under sexual selection. A total of 258 specimens, 161 males, 81 females, 16 juveniles, were collected from Mound 12 at 1,000-1,040 m depth in 2017 and 2018 and analyzed. We found that males have larger and wider claws than females, while there were no differences in carpus length. These results suggest that claw weaponry is under sexual selection in K. puravida, which is probably related to the mating system of this deep-sea species. This is the first attempt to study the reproductive biology of K. puravida, and additional observations will be necessary to shed more light on this matter.

Abstract Thoe Bell, 1836 is amphi-American in distribution and includes small spider crabs with cryptic habits and rare records in the literature and carcinological collections. The taxonomy of the three recent and two fossil species currently known in the genus has been revised. A phylogenetic reconstruction conducted here based on the mitochondrial markers COI and 16S rRNA supports the monophyletic status of Thoe. The resulting phylogeny suggests a western Atlantic to eastern Pacific radiation of the genus.

Clipperton, an uninhabited and remote coral atoll from the Eastern Pacific, is an important steppingstone area that harbors a high marine biodiversity. Despite its biogeographic importance, little information on the ecological status of its coral reefs is available from the last decade. Herein, we characterized the benthic coral community and health status among four different shallow reef-zones (North to South) of Clipperton during the Tara Pacific expedition in 2018. The benthic composition (expressed as coverage percentage), as well as occurrence of potential disease-like phenotypes, in particular a pink-spotted coral phenotype was assessed. Average live coral cover on Clipperton reefs was 66% (range 55–85%), differing between sites, with massive Porites and branching Pocillopora corals dominating the benthic community with an average 48% (32–66%), and 15% (3–21%), respectively. While Clipperton reefs exhibited significant live coral cover overall, and no other disease-like phenotypic were observed, the pink-spotted coral phenotype was common, with a higher occurrence in massive corals (Porites 27%, and Pavona 31%). This observation may be related to the combined effects of previously heatwaves, and local inputs of guano-derived nutrients discharged during storms and hurricanes, which may suggest that even highly remote reefs supporting high coral cover can be subject to local and global threats. An alternative hypothesis is that the observation of a healthy reef with high coral cover and high incidence of pink-spotted coral phenotype in the absence of other diseases might reflect potential infection with the parasitic trematode Podocotyloides stenometra. While this hypothesis will have to be confirmed by histological and molecular analysis, it may be possible that larvae of this trematode may experience favorable conditions due to periodic nutrient input frorm the nutrient-rich lagoon or via guano run-off of Clipperton Island. [ABSTRACT FROM AUTHOR]

A time‐series analysis of Easterly Wave (EW) activity, based on dynamical and convective variance measures, was carried out over the tropical northeastern Pacific (EPAC). A significant interdecadal change in EW‐activity was identified shifting from reduced activity in 1980–1997, to increased activity during 1998–2015. The changes in EW‐activity are modulated on interdecadal timescales by the Atlantic Multidecadal Oscillation (AMO) and the Pacific Decadal Oscillation (PDO). EW‐activity is increased when there is a positive AMO index and, to a lesser extent, a negative PDO index. The opposite occurred with a negative AMO index and positive PDO index. This relationship can be understood in terms of how the AMO and PDO impact sea surface temperatures (SSTs) in the EPAC. Warmer SSTs tend to be associated with more EW‐related convection and associated vorticity generation in the EW troughs and vice versa. These results suggest potential predictability of EW‐activity in the EPAC on interdecadal timescales. Plain Language Summary: Easterly Waves (EWs) are westward‐propagating synoptic disturbances found over many tropical regions. They are an important source of rainfall for continental regions, and can be a precursor for tropical cyclones. Over the tropical northeastern Pacific, this research has highlighted a significant interdecadal change on Easterly Wave activity, shifting from reduced activity during 1980–1997 to increased activity in 1998–2015. This is linked with anomalies in the sea surface temperatures (SSTs), with warm values resulting in more Easterly Wave related convection and enhanced vorticity, and vice versa. Interdecadal variability of SSTs in this region is related to the Atlantic Multidecadal Oscillation (AMO) and the Pacific Decadal Oscillation (PDO). Enhanced Easterly Wave activity is favored in the positive phase of the AMO, and to a lesser extent, with the negative phase of the PDO, both associated with warm SSTs. Key Points: Easterly Waves (EWs) over the tropical northeastern Pacific vary on interdecadal timescales, modulated by sea surface temperatures (SSTs)SSTs are modulated by the Atlantic Multidecadal Oscillation (AMO) and the Pacific Decadal Oscillation (PDO)Increased EWs activity is associated with positive AMO and negative PDO [ABSTRACT FROM AUTHOR]

Aim: Biogeographic history and variation in modern environmental conditions can greatly influence local and regional community structure and, more generally, ecosystem functioning. This is clearly exemplified at the Isthmus of Panama where marine communities and environments from the Caribbean Sea and the Tropical Eastern Pacific Ocean differ despite ancient connections during the Miocene and Pleistocene. Here, we compare the functional (implied from traits) and isotopic structure of mangrove fish communities from those two biogeographic regions, which have been separated by the Isthmus of Panama for ~3 my. Location: Caribbean and Pacific coasts of Panama (Eastern Pacific and Caribbean Sea). Methods: We gathered data on five functional traits (salinity preference, body mass, diet, position in the water column and lifespan) of mangrove fishes from the sampled regions. We also analysed δ13C and δ15C isotopic values and calculated functional isotopic metrics of the most abundant fish species inhabiting mangroves of these two regions. Results: The taxonomic composition and functional and trophic diversity differed between the mangrove fish communities of the Caribbean and the Eastern Pacific. Although the species richness of both assemblages was similar, there was very little taxonomic overlap between them: Snooks (Centropomidae) numerically dominated in the Eastern Pacific, whereas grunts (Haemulidae) and snappers (Lutjanidae) dominated in the Caribbean Sea. Functional divergence (FDiv) and isotopic richness (IRic) were higher in the Caribbean than in the Eastern Pacific, indicating differences in the way fishes use mangroves in these areas. Main conclusions: Taxonomic and functional characteristics of mangrove fish assemblages across biogeographic realms can be strongly influenced by local environmental factors (e.g. tidal regimes, the presence of adjacent coastal ecosystems and productivity), and these can override similarities that recent historical connections of faunas might be expected to produce. All such aspects need to be considered when seeking generalizations about ecosystem functioning. [ABSTRACT FROM AUTHOR]

Background: The first successful application of implanted archival tags on striped marlin showed great potential in obtaining long-term tracks for an improved understanding of movement ecology, which is important for informing fisheries management decisions. Ten tags were physically recovered from fish tagged in the Eastern Pacific between 2008 and 2016, but unfortunately due to the failure of the external sensor stalk which houses the light sensor, full records of daily fish position could not be attained. Results: Depth-based geolocation, which exploits the diel swimming patterns of striped marlin, was applied to derive position estimates for archival tagged fish up to 7.7 years. Reconstructed tracks revealed tagged striped marlin remained in the Eastern Pacific throughout the tracked duration. Trans-equatorial movements were also documented for the first time for striped marlin in this region, as were extended occupancy of > 1 year in pelagic waters. Conclusions: Striped marlin connected both coastal and offshore habitats with seasonal runs, likely in fulfillment of their life history requirements from foraging to reproduction. Circadian rhythms in billfish and other pelagic fishes are well-established, and could provide a viable, alternative means to position an individual in a low or no light environment, and situations with sub-optimal or limited bio-logging capabilities. Depth-based geolocation, however rudimentary, has revealed variability in striped marlin horizontal movements over the multi-year observation period, and offered a unique spatiotemporal perspective that was unavailable to scientists and fisheries managers until now. [ABSTRACT FROM AUTHOR]