Oceanic Species Research Articles

Sub Aquatic Image Correction with Oceanic Species Eye Mechanism using MATLAB

Abstract: Our work is based on the idea of improving underwater images based on the structure and function of the subaquatic ocean species retina. Our goal is to solve image degradation problems caused by blurry and uneven colors. Our design also compares various image enhancement techniques using different filters and contrasts and compares the results. Fishes have retinas with rods and cones that help them to see images clearly under the water. Color contrast is specially corrected using the red correction line and feedback from the horizontal line. Because a single image is used, this method does not require special equipment or knowledge of underwater structures or the underwater environment. Higher contrast, sharper edges and better visibility in the dark means better photos and videos. The algorithm is mostly independent of camera settings. Index: Underwater Imaging, White Balance, Color Correction

Biogeography and evolution of social parasitism in Australian Myrmecia bulldog ants revealed by phylogenomics

Studying the historical biogeography and life history transitions from eusocial colony life to social parasitism contributes to our understanding of the evolutionary mechanisms generating biodiversity in eusocial insects. The ants in the genus Myrmecia are a well-suited system for testing evolutionary hypotheses about how their species diversity was assembled through time because the genus is endemic to Australia with the single exception of the species M. apicalis inhabiting the Pacific Island of New Caledonia, and because at least one social parasite species exists in the genus. However, the evolutionary mechanisms underlying the disjunct biogeographic distribution of M. apicalis and the life history transition(s) to social parasitism remain unexplored. To study the biogeographic origin of the isolated, oceanic species M. apicalis and to reveal the origin and evolution of social parasitism in the genus, we reconstructed a comprehensive phylogeny of the ant subfamily Myrmeciinae. We utilized Ultra Conserved Elements (UCEs) as molecular markers to generate a molecular genetic dataset consisting of 2,287 loci per taxon on average for 66 out of the 93 known Myrmecia species as well as for the sister lineage Nothomyrmecia macrops and selected outgroups. Our time-calibrated phylogeny inferred that: (i) stem Myrmeciinae originated during the Paleocene ∼ 58 Ma ago; (ii) the current disjunct biogeographic distribution of M. apicalis was driven by long-distance dispersal from Australia to New Caledonia during the Miocene ∼ 14 Ma ago; (iii) the single social parasite species, M. inquilina, evolved directly from one of the two known host species, M. nigriceps, in sympatry via the intraspecific route of social parasite evolution; and (iv) 5 of the 9 previously established taxonomic species groups are non-monophyletic. We suggest minor changes to reconcile the molecular phylogenetic results with the taxonomic classification. Our study enhances our understanding of the evolution and biogeography of Australian bulldog ants, contributes to our knowledge about the evolution of social parasitism in ants, and provides a solid phylogenetic foundation for future inquiries into the biology, taxonomy, and classification of Myrmeciinae.

Genetic diversity, distribution, and structure of Bemisia tabaci whitefly species in potential invasion and hybridization regions of East Africa.

Outbreaks of whitefly, Bemisia tabaci species in East and Central Africa, have become increasingly prevalent during the previous 25 years and are responsible for driving the spread of plant-virus diseases, such as cassava mosaic disease and cassava brown steak disease. Epidemics of these diseases have expanded their ranges over the same period, spreading from Uganda into other sub-Saharan African countries. It was hypothesised that a highly abundant 'invader' population of B. tabaci was responsible for spreading these diseases from Uganda to neighbouring countries and potentially hybridising with the resident cassava B. tabaci populations. Here, we test this hypothesis by investigating the molecular identities of the highly abundant cassava B. tabaci populations from their supposed origin in Uganda, to the northern, central, eastern and coastal regions of Tanzania. Partial mitochondrial cytochrome oxidase I (mtCOI) barcoding sequences and nuclear microsatellite markers were used to analyse the population genetic diversity and structure of 2734 B. tabaci collected from both countries and in different agroecological zones. The results revealed that: (i) the putative SSA1 species is structured according to countries, so differ between them. (ii) Restricted gene flow occurred between SSA1-SG3 and both other SSA1 subgroups (SG1 and SG2), even in sympatry, demonstrating strong barriers to hybridization between those genotypes. (iii) Not only B. tabaci SSA1-(SG1 and SG2) was found in highly abundant (outbreak) numbers, but B. tabaci SSA1-SG3 and the Indian Ocean (IO) species were also recorded in high numbers in several sites in Tanzania. (iv) The SSA1-(SG1 and SG2) species was distributed in both countries, but in Tanzania, the B. tabaci IO and SSA1-SG3 species predominated. These data confirm that multiple, local Tanzanian B. tabaci species produce highly abundant populations, independent of the spread of the putative invasive B. tabaci SSA1-(SG1 and SG2) populations.

New Zealand's media and the crisis in the ocean: News norms and scientific urgency

Abstract To date, no studies have analysed New Zealand's media coverage of ocean‐related threats, potential harms, or sources used for their coverage. This is concerning given that marine media coverage is linked to public support, awareness of conservation issues, and policymaking. This research helps fill this gap, examining all ocean‐related articles 2 weeks before and after the 2019 Intergovernmental Panel on Climate Change (IPCC) report's release on the oceans and cryosphere. It first analyses the media's reporting of threats, potential harms arising from the threats, and the sources on whom journalists relied and gave voice, then it tests a report of global significance for influence on reportage. Second, it examines whether the threats covered by media align with scientists' main concerns (from the IPCC report and a survey of New Zealand scientists). In contrast to previous studies on media sources for environmental conservation, this study found that journalists in New Zealand relied considerably on scientists as key sources. However, it found that coverage of ocean‐related threats did not match scientists' main concerns. Finally, the research found that the IPCC report appeared to influence coverage in two areas: reporting on threats to island nations, and multiple potential harms. Otherwise, New Zealand's media covered the IPCC report as any other news item, reporting on it and then shifting to other matters. The lack of coverage on primary scientific concerns and that a globally significant momentous report did not dramatically impact the marine media landscape is problematic for conservation of ocean habitats, species, and broader environmental and societal outcomes owing to poor understandings by policymakers and the public, which can lead to inaction and policy failures. The potential reasons and solutions to advance communication of marine conservation issues for a more educated and mobilized public are explored.

The high ventricular function in the shortfin mako shark (Isurus oxyrinchus)

The shortfin mako sharks ( Isurus oxyrinchus) belongs to the family Lamnidae, which is a group of high performance regional endothermic elasmobranch fishes that has metabolic rates (47.4±8 ml/kg/min) higher than ectothermic elasmobranchs, and also rivals that of mammals. As in all elasmobranchs, the mako sharks do not possess direct cardiac sympathetic innervation to elevate cardiac performance, but it still retains an ancient design of a capacious semi-rigid pericardium (5.4±0.6 ml/kg) likely to accommodate its large atrial diastolic volume. This study test the hypothesis that the increase in cardiac output in the mako is influenced by a strong positive lusitrophic effect that serves to increase stroke volume, which in turn invokes the Frank-Starling’s effects. The objectives is to show differences in the physiology and biochemical properties between mako (Is) and an ectothermic blue shark ( Prioance glauca, Pg), both are oceanic species and share similar life history. Echocardiography showed a higher early to late filling velocity ratio (p=0.036) in the Is (0.92±0.16, [n=15]) than in Pg (0.45±0.04, [9]). The early time velocity integral is also greater in Is (8.8±2.4 cm, [15]) vs Pg (6.8±0.8 cm [9]) indicating a stronger conduit filling imparted by the energy from previous systole in Is. However, basal cAMP (Is: 31±12 [7] vs Pg: 31±1 [3] fmol/min/μg) and stimulated cAMP with isoproterenol+GTPγS (Is: 65±21 [7] vs Pg: 59±7 [3] fmol/min/μg) activity are similar in both groups. This suggests that the differences in ventricular contractility are not through the classic adrenergic signaling pathway involving adenylyl cyclases, but likely through the mechanical stretching of the myofibrils from diastole. Caveolin distribution of the ventricular tissues following sucrose density gradient shows a higher degree of Caveolin-1/3 in the buoyant fraction and little in the in the heavy fraction in both shark species indicating an absence of t-tubules. However, Is shows a remarkably high amount of buoyant Cav-1/3 fraction compared to Pg. We posit that the high fraction abundance of Cav-1/3 provides a gateway for corticotropin-releasing factor, such as urotensin I or possibly an ancestral precursor of urocortin, which has been shown to elevate heart function in mammals. The study is supported by NSF IBN93-16621. No disclosure. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Fish otolith record reveals possible tropical-subtropical fish community in temperate Japan during the exceptionally warm Last Interglacial period

ABSTRACT Glacial-interglacial cycles are characteristic of the large-scale reorganisation of global climate during the Quaternary. Therefore, records of warmer-than-present periods, such as the Marine Isotope Stage (MIS) 5e, draw particular interest as they may aid scientists to predict how marine ecosystems may change in the future. However, fish fossil records during such warming periods are less clear. Here, we aim to reconstruct local fish fauna during the MIS 5e by describing fossil otoliths from two localities in central Japan belonging to the Otsu Sand and Mud Member of the Yokosuka Formation. A total of 544 otoliths were analysed, revealing the presence of at least 35 taxa. The fish assemblages reflect a mixture of coastal to oceanic epi-mesopelagic species. In addition, the remarkable occurrences of two present-day tropical species and its species composition demonstrate a possible complex tropical to subtropical-like fish fauna in the higher latitude Palaeo-Tokyo Bay during the warmer-than-present last interglacial period.

Metabarcoding of ichthyoplankton communities associated with a highly dynamic shelf region of the southwest Indian Ocean.

Drifting fish eggs and larvae (ichthyoplankton) can be identified to species using DNA metabarcoding, thus allowing for post hoc community analyses at a high taxonomic resolution. We undertook a regional-scale study of ichthyoplankton distribution along the east coast of South Africa, focused on the contrasting environments of the tropical Delagoa and subtropical Natal Ecoregions, and on exposed and sheltered shelf areas. Zooplankton samples were collected with tow nets at discrete stations along cross-shelf transects (20-200 m depth) spaced along a latitudinal gradient that incorporates a known biogeographical boundary. Metabarcoding detected 67 fish species, of which 64 matched prior distribution records of fishes from South Africa, with the remaining three known from the Western Indian Ocean. Coastal, neritic and oceanic species were present, from epi- and mesopelagic to benthopelagic and benthic adult habitats. By family, Myctophidae (10 species), Carangidae, Clupeidae, Labridae (each with 4 species) and Haemulidae (3 species) were most speciose. Ichthyoplankton community composition varied significantly with latitude, distance to coast, and distance to the shelf edge. Small pelagic fishes had the highest frequency of occurrence: Engraulis capensis, Emmelichthys nitidus and Benthosema pterotum increased in frequency towards the north, whereas Etrumeus whiteheadi increased towards the south. Chub mackerel Scomber japonicus accounted for most variability related to distance from the coast, whilst African scad Trachurus delagoa correlated with distance to the shelf edge. Dissimilarity between communities in the Delagoa and Natal Ecoregions was 98-100%, whereas neighbouring transects located within the sheltered KwaZulu-Natal Bight had lower dissimilarity (56-86%). Onshore transport of ichthyoplankton by Agulhas Current intrusions plausibly explained the abundance of mesopelagic species over the shelf. Metabarcoding followed by community analysis revealed a latitudinal gradient in the ichthyoplankton, associations with coastal and shelf-edge processes, and evidence of a spawning area in the sheltered KwaZulu-Natal Bight.

Ophryotrocha (Dorvilleidae, Polychaeta, Annelida) from deep-sea hydrothermal vents, with the description of five new species

Dorvilleids belonging to Ophryotrocha Claparède & Mecznikow, 1869 are known from deep-sea hydrothermal vents in the Pacific, Atlantic, Indian and Southern Oceans. However, how they colonized and diversified in these ecosystems has not been assessed in detail. Here, a collection of Pacific hydrothermal vent Ophryotrocha was examined using morphology and DNA markers (COI, 16S and H3). Five new species were revealed, largely expanding the diversity of the group at this habitat type. They are Ophryotrocha charlottae sp. nov., O. kailae sp. nov., O. marinae sp. nov., O. pruittae sp. nov. from eastern Pacific, and O. bohnorum sp. nov. from the western Pacific. Phylogenetic analyses based on the concatenated alignments of all three genes suggest vent habitants have been colonized several times independently within Ophryotrocha. One clade of six vent species was recovered, indicative of diversification following a colonization of hydrothermal vents, likely in the eastern Pacific. An Indian Ocean species, O. jiaolongi, was nested inside this clade and was closely related to one of the new species from the Gulf of California, diverging from it by less than 4% on COI.

Eurythenes sigmiferus and Eurythenes andhakarae (Crustacea: Amphipoda) are sympatric at the abyssal Agulhas Fracture Zone, South Atlantic Ocean, and notes on their distributions

Cryptic species in the deep ocean are rapidly being identified with molecular evidence and as a result, new species are being described. Consequently, our understanding of distributions among the revised landscape of species needs to be reassessed. A model example is the large scavenging amphipod, Eurythenes gryllus (Lichtenstein in Mandt, 1882), which historically was thought to have a eurybathic and cosmopolitan distribution. Molecular evidence has since led to the separation of E. gryllus into ten named species and truncating its range to bi-polar bathyal depths. This study focuses on two species; Eurythenes sigmiferus and Eurythenes andhakarae d'Udekem d'Acoz and Havermans, 2015, and presents new records of both species from 5,493 m in the previously unsampled Agulhas Fracture Zone, South Atlantic Ocean (42.77°S, 10.05°E). We paired morphology with DNA barcoding at two mitochondrial regions to achieve robust identification and assessed their wider geographic range by reassessing historical records. Their overlapping presence at the Agulhas Fracture Zone expands their known ranges to the non-polar South Atlantic Ocean. Specifically, for E. sigmiferus, the data suggests this species has a multi-ocean tropical to temperate distribution from abyssal to shallow hadal depths (3,410–6,097 m). Eurythenes andhakarae is not restricted to the Southern Ocean but is distributed across the Antarctic Polar Front to the temperate South Atlantic Ocean between abyssal and hadal depths (3,069–7,099 m), with a presence at bathyal depths requiring molecular confirmation. This study highlights that pairing new expeditions with a re-inspection of rich historical collections exploration can fill in data gaps across species ranges and, ultimately, biogeography.

Assemblage Distribution of the Larval and Juvenile Myctophid Fish in the Kuroshio Extension Region: Winter 2020

Myctophids are an ecologically important mesopelagic species in the eastern Pacific Ocean. Due to the wide distribution, great diversity and variable biological characteristics of the species, there is a lack of reliable information regarding their spawning and nursery grounds in the Kuroshio extension region. In this study, we identified a total of 110 myctophid individuals using DNA barcoding and morphological techniques, among which, the dominant genus was Ceratoscopelus, comprising 37.27% of the entire catch. The abundance of each sampling station was calculated, and its relationship with environmental variables was analyzed. Tweedie-Generalized Additive Model (GAM) analysis showed that copepod density, oceanic dynamic processes, and sea surface temperature were the primary factors influencing the distribution pattern of larvae and juvenile myctophid fish. The results further indicate that the Kuroshio extension plays a dominant role in the biological processes of these fish in this region. These findings provide crucial dynamic information for the scientific conservation and exploitation of myctophids, which could have significant implications for the management of these fish populations.

Summer Habitat and Fishing Ground of <i>Ommastrephes bartramii</i> Related with the North Pacific Subarctic Frontal Zone Using Long-term Field Research Data

The neon flying squid, Ommastrephes bartramii, is an economically important oceanic squid species that has been harvested commercially in the North Pacific by Japan, Korea, China, and Taiwan. The Fisheries Research Agency (FRA) of Japan conducted long-term research for this species from 1980 to 2009 using commercial vessels to clarify the resource ecology and it obtained a total dataset of approximately 9,000 days, where following from this and to better clarify the relationship between habitat preference and oceanographic conditions, a generalized additive model was applied and mapped onto the Simple Ocean Data Assimilation ocean/sea ice reanalysis (SODA) data. The resultant habitat map of the squid showed an area of high abundance at the Subarctic Frontal Zone (SAFZ), with abundance areas increasing the squid abundance from April to August. The SAFZ extends from 40°N to 43°N separating the cold, low-salinity, subarctic water to the north from the waters of the North Pacific Transition Zone to the south. This high abundance area intersects between subarctic area and temperate area. It has characteristic nutrient regimes, productivity cycles, and nektonic faunal compositions. This paper suggests that the SAFZ thus plays an important role in North Pacific ecosystems by providing an optimal balance between environmental temperature and food density for the neon flying squid.

The diatom Fragilariopsis cylindrus: A model alga to understand cold-adapted life.

Diatoms are significant primary producers especially in cold, turbulent, and nutrient-rich surface oceans. Hence, they are abundant in polar oceans, but also underpin most of the polar food webs and related biogeochemical cycles. The cold-adapted pennate diatom Fragilariopsis cylindrus is considered a keystone species in polar oceans and sea ice because it can thrive under different environmental conditions if temperatures are low. In this perspective paper, we provide insights into the latest molecular work that has been done on F. cylindrus and discuss its role as a model alga to understand cold-adapted life.

Distribution and densities of fish larvae species with contrasting life histories as a function of oceanographic variables in the deep-water region of the southern Gulf of Mexico.

We describe the larval occurrence and density of six fish species with contrasting life histories and examine their relationships with oceanographic variables during two seasons in the deep-water region (> 1000 m) of the southern Gulf of Mexico based on 12 cruises (2011-2018). Given that Caranx crysos adults are neritic, larval presence close to the continental shelf indicates offshore cross-shelf transport to oceanic waters, which likely leads to mortality. Generalized additive models indicated that C. crysos density was not related with oceanographic variables, while Auxis spp. (with neritic and oceanic adults) was related to wind speed, sea surface temperature, sea surface height, and surface chlorophyll a. The mesopelagic Benthosema suborbitale, Notolychnus valdiviae and Bregmaceros atlanticus were more abundant and broadly distributed, and higher density was found in conditions indicative of higher nutrient availability and productivity, suggesting greater feeding success and survival. The distribution of the epi- and mesopelagic Cubiceps pauciradiatus extended through the southern Gulf of Mexico, and was related to wind speed, sea surface temperature, stratification and chlorophyll a. Our results suggest that the density of the neritic species in oceanic waters could be mediated by regional cross-shelf transport, while for oceanic species is linked with productivity.

Quantifying the feeding behavior and trophic impact of a widespread oceanic ctenophore

Oceanic ctenophores are widespread predators on pelagic zooplankton. While data on coastal ctenophores often show strong top-down predatory impacts in their ecosystems, differing morphologies, prey capture mechanisms and behaviors of oceanic species preclude the use of coastal data to draw conclusion on oceanic species. We used high-resolution imaging methods both in situ and in the laboratory to quantify interactions of Ocyropsis spp. with natural copepod prey. We confirmed that Ocyropsis spp. uses muscular lobe contraction and a prehensile mouth to capture prey, which is unique amongst ctenophores. This feeding mechanism results in high overall capture success whether encountering single or multiple prey between the lobes (71 and 81% respectively). However, multiple prey require several attempts for successful capture whereas single prey are often captured on the first attempt. Digestion of adult copepods takes 44 min at 25 °C and does not vary with ctenophore size. At high natural densities, we estimate that Ocyropsis spp. consume up to 40% of the daily copepod standing stock. This suggests that, when numerous, Ocyropsis spp. can exert strong top-down control on oceanic copepod populations. At more common densities, these animals consume only a small proportion of the daily copepod standing stock. However, compared to data from pelagic fishes and oceanic medusae, Ocyropsis spp. appears to be the dominant copepod predator in this habitat.

Diatom distribution in Holocene sediments from the northern West Caroline Basin (western equatorial Pacific) and their environmental significance

Diatoms are an important component of submarine biogenic sediments and often used for carrying out palaeoceanographical reconstructions. To understand the relationship between diatoms and environment in the western equatorial Pacific, diatoms from the Holocene sediments in the northern West Caroline Basin were selected for analysis. We made quantitative statistics on diatoms and divided diatom assemblages through cluster analysis. A total of 53 species or varieties of diatoms belonging to 22 genera were identified. The range of diatom abundance was 0-88,373 valves/g. The diatoms found were mainly oceanic warm-water species. Overall, Azpeitia nodulifera was the species with the highest contribution, followed by Hemidiscus cuneiformis and Thalassiosira pacifica with these three species together accounting for approximately 80% in this area. We identified four diatom groupings and divided the study area into three regions. Diatom assemblage I in the West Caroline Basin was mainly affected by the North Equatorial Counter Current (NECC), Antarctic Intermediate Water (AAIW) and upwelling, and the supply of nutrients was relatively high. Assemblage II in the West Caroline Ridge was less influenced by currents, and thus had lower abundance and species diversity than assemblage I. The complex diatom assemblages in the Yap Trench were probably controlled by Upper Circumpolar Deep Water (UCPW) and Lower Circumpolar Deep Water (LCPW).

Structure and function of ABC transporters in oceanic species.

The pollution of the world's oceans is a mounting problem that threatens the safety and well-being of our planet. Many marine organisms and ecosystems are exposed to pollutants with currently unknown toxicity and consequences. Membrane proteins that act as xenobiotic - foreign molecule - exporters are an important line of defense against pollutants in the organisms’ environment. One of the most ubiquitous membrane transporter proteins are the ATP binding cassette transporters (ABC). Found in organisms across all domains of life and in many tissue types, ABC transporters selectively export many different small molecules from within the cell, preventing the toxic accumulation of xenobiotics within the organism. Many of the small molecules exported by ABC transporters are pollutants. However, some small molecule pollutants may act as inhibitors of ABC transporters by interacting with their binding site and impeding transport. For example, a study conducted on one transporter - ABCB1 or P-glycoprotein - in mice found that transport activity was significantly reduced in the presence of DDD, DDE, and DDT. In the case of ABC transporters in oceanic species, many reagents found polluting the ocean may inhibit ABC transporters’ ability to export their wide range of substrates. This would lead to detrimental effects to the health of organisms in the oceanic food chain (e.g. yellowfin tuna) and to embryonic development (e.g. purple sea urchin). A thorough molecular and structural investigation of these transporters expressed in marine species is necessary to determine which chemicals inhibit transport. Using cryo-EM and x-ray crystallography, we intend to study the structure of the ABC transporter active site and the differences between activating and inhibiting molecular transport.

Spatial and temporal dynamics of whalewatching in Península Valdés, Patagonia, Argentina

Península Valdés (Patagonia, Argentina) is considered one of the best places in the world to watch southern right whales (Eubalaena australis) due to the large number of animals as well as to their predictability and proximity to the coast. The present study describes the spatial and temporal dynamics of whalewatching, and the different groups of whales that were the focus of this activity in Península Valdés during six reproductive seasons (from 2005 to 2008 and from 2012 to 2013). The aim was to generate useful tools to improve whalewatching activity in this area. Data were recorded from 1,816 whalewatching trips operated from Puerto Pirámides. Every trip had several stopovers to watch whales, defined as ‘sightings’. At the beginning of the season, most sightings occurred near Puerto Pirámides port, while at the end of the season, sightings were farther from the port. During the first half of the whale season, trips tended to be coastal and shorter but the groups of whales sighted were more varied, including solitary animals, mating groups and mothers with their recently born calves. In the second half of the season, trips tended to be further from the coast and longer, but the whales sighted were mainly mother-calf pairs, the last group of whales to leave the area. This difference in the characteristics of the sightings as the whale season progressed could be the basis to generate different recreational experience opportunities. Whalewatching has a major impact on the regional economy and whalewatching regulations, if correctly applied, could improve the quality of a conservation plan, considering that both gulfs of Península Valdés (San José and Nuevo) are the main calving areas for this species in the South Atlantic Ocean.

A century of mercury: Ecosystem-wide changes drive increasing contamination of a tropical seabird species in the South Atlantic Ocean

Mercury (Hg) is a highly toxic metal that adversely impacts human and wildlife health. The amount of Hg released globally in the environment has increased steadily since the Industrial Revolution, resulting in growing contamination in biota. Seabirds have been extensively studied to monitor Hg contamination in the world's oceans. Multidecadal increases in seabird Hg contamination have been documented in polar, temperate and subtropical regions, whereas in tropical regions they are largely unknown. Since seabirds accumulate Hg mainly from their diet, their trophic ecology is fundamental in understanding their Hg exposure over time. Here, we used the sooty tern (Onychoprion fuscatus), the most abundant tropical seabird, as bioindicator of temporal variations in Hg transfer to marine predators in tropical ecosystems, in response to trophic changes and other potential drivers. Body feathers were sampled from 220 sooty terns, from museum specimens (n = 134) and free-living birds (n = 86) from Ascension Island, in the South Atlantic Ocean, over 145 years (1876–2021). Chemical analyses included (i) total- and methyl-Hg, and (ii) carbon (δ1³C) and nitrogen (δ15N) stable isotopes, as proxies of foraging habitat and trophic position, respectively, to investigate the relationship between trophic ecology and Hg contamination over time. Despite current regulations on its global emissions, mean Hg concentrations were 58.9% higher in the 2020s (2.0 μg g−1, n = 34) than in the 1920s (1.2 μg g−1, n = 107). Feather Hg concentrations were negatively and positively associated with δ1³C and δ15N values, respectively. The sharp decline of 2.9 ‰ in δ1³C values over time indicates ecosystem-wide changes (shifting primary productivity) in the tropical South Atlantic Ocean and can help explain the observed increase in terns' feather Hg concentrations. Overall, this study provides invaluable information on how ecosystem-wide changes can increase Hg contamination of tropical marine predators and reinforces the need for long-term regulations of harmful contaminants at the global scale.

VoluModel: Modelling species distributions in three‐dimensional space

Abstract Ecological niche modelling (ENM), species distribution modelling and related spatial analytical methods were first developed in two‐dimensional (2‐D) terrestrial systems; many common ENM workflows organize and analyse geographically structured occurrence and environmental data based on 2‐D latitude and longitude coordinates. This may be suitable for most terrestrial organisms, but pelagic marine species are distributed not only horizontally but also vertically. Extracting environmental data for marine species based only on latitude and longitude coordinates may result in poorly trained ENMs and inaccurate prediction of species' geographical distributions, as water conditions may vary strikingly with depth. We developed the voluModel R package to efficiently extract three‐dimensional (3‐D) environmental data for training ENMs (i.e. presences and absences/pseudoabsences/background). voluModel also provides tools for 3‐D ENM projection visualization and estimation of model extrapolation risk. We present the main features of the voluModel R package and provide a simple modelling workflow for Luminous Hake, Steindachneria argentea, as an example. We also compare results from 2‐D and 3‐D spatial models to demonstrate differences in how the modelling methods perform. The use of 3‐D environmental data generates more precise estimates of environmental conditions for training ENMs. This method also improves inference of species' suitable abiotic ecological niches and potential geographic ranges. 3‐D niche modelling is important step forward for marine macroecology and biogeography, as it will yield more accurate estimates of ocean species richness and potential past and future changes in the horizontal and vertical dimensions of species' geographic ranges. The latter is particularly relevant considering ongoing climate change that may cause redistribution of species in environmental space (both in latitude and depth) over time.

Trends and gaps in marine mammal research from Mexico during 1998 – 2021

Marine mammals are very diverse because of the oceanographic conditions of Mexican waters (where 36% of the current species worldwide are found); however, scientific research on many of these taxa is still at the basic stages. The goal of this study was to assess the scientific information available for these species and to determine research priorities through a GAP (from the acronym "Good", "Average", and "Poor”) analysis. Information from the abstracts of the meetings held by the Mexican Society of Marine Mammalogy (SOMEMMA) and online databases (SCOPUS and Web of Science) between 1998 and 2021 was analyzed using temporal (years), geographic (oceans or states), taxonomic (species), and thematic (topics) classifications. On average, of the 44 species included in the Mexican legislation, only 16 - included in 14 families (with most of the records) - are studied every year, Delphinidae (n = 500; 25.9%), Balaenopteridae (n = 335; 17.4%), and Otariidae (n = 316; 16.4%). The Gulf of California was the most studied region (35.4%), followed by the Northeast Pacific (19.3%), the Gulf of Mexico (15.5%), and the Caribbean Sea (6.9%). The most frequent topics were population ecology (32.9%), conservation (16.7%), and animal health (10.4%). A significant decrease in the taxonomic and thematic diversity of such studies has been noted since SOMEMMA meetings began to be held on a biennial basis. It is noteworthy that marine mammals are protected by Mexican Federal laws. However, stock assessments are not mandatory, therefore biological aspects and trends of several (mostly oceanic) species remain unknown in many places, especially in regions where academic and scientific institutions are not involved in marine science.