Recent sio items

Resolving abrupt frontal gradients in zooplankton community composition and marine snow fields with an autonomous Zooglider

Thu, 18 Jun 2026 00:00:00 +0000

Abstract An autonomous Zooglider navigated across the California Current Front into low salinity, minty waters characteristic of the California Current proper in both summers of 2019 and 2021. Diving to 400 m depth, Zooglider transited another near‐surface frontal gradient somewhat inshore. These frontal gradients were generally associated with changes in intensity, size composition, and Diel Vertical Migration responses of acoustic backscatterers. They were also associated with pronounced changes in zooplankton community composition, as assessed by a shadowgraph imaging Zoocam. Zoocam detected a decline in concentrations of copepods, appendicularians, and marine snow in the offshore direction, and an overall shift in community structure to a higher proportion of carnivorous taxa (and, in 2019, of planktonic rhizaria). No taxon was consistently elevated at all the peak frontal gradients, but appendicularians, copepods, and rhizarians sometimes showed front‐related increases in...

Diverse sampling programs highlight pulses of Velella velella along the US West Coast.

Thu, 18 Jun 2026 00:00:00 +0000

Sporadic mass strandings of the hydrozoan, Velella velella, along the US West Coast fascinate beachcombers and perplex oceanographers. Velella often arrive to the coast in the spring concurrent with a shift in onshore winds and after winters with warmer water temperatures. Understanding the factors that bring Velella to coastal waters provides new information about the ecological impacts of local and basin-scale environmental variability in the northeast Pacific. We summarize several compelling, non-exclusive hypotheses that could explain the recent increase in Velella, including increased population size, larger surface patches and enhanced coastward transport. We compiled a comprehensive dataset spanning planktonic larval to colonial adult life stages from 10 sources covering ~1900-2025. We highlight pulses of Velella and an unprecedented number of strandings and at-sea observations since 2014. We found that wind patterns in the central-east...

Fine scale zooplankton distribution across the North Balearic Front during late spring

Thu, 18 Jun 2026 00:00:00 +0000

Observations, models and theory have suggested that ocean fronts are ecological hotspots, generally associated with higher diversity and biomass across many trophic levels. Nutrient injections are often associated with higher chlorophyll concentrations at fronts, but the response of the zooplankton community is largely unknown. The present study investigates mesozooplankton stocks and composition during late spring, northeast of Menorca along two north-south transects that crossed the North Balearic Front (NBF) separating central water of the Northwestern Mediterranean Sea (NWMS) gyre from peripheral waters originating from the Algerian basin. During the BioSWOT-Med campaign, samples were collected using vertical triple net tows at three depths (100 m, 200 m, 400 m) with 200 μm and 500 μm mesh nets, processed with ZooScan, and the organisms assigned to eight taxonomic groups. Zooplankton distributions were analysed for the surface (0–100 m), intermediate (100–200 m), and deeper...

Relationships Between Plankton Size Spectra, Net Primary Production, and the Biological Carbon Pump

Thu, 18 Jun 2026 00:00:00 +0000

Abstract Photosynthesis in the surface ocean and subsequent export of a fraction of this fixed carbon leads to carbon dioxide sequestration in the deep ocean. Ecological relationships among plankton functional groups and theoretical relationships between particle size and sinking rate suggest that carbon export from the euphotic zone is more efficient when communities are dominated by large organisms. However, this hypothesis has never been tested against measured size spectra spanning the >5 orders of magnitude found in plankton communities. Using data from five ocean regions (California Current Ecosystem, North Pacific subtropical gyre, Costa Rica Dome, Gulf of Mexico, and Southern Ocean subtropical front), we quantified carbon‐based plankton size spectra from heterotrophic bacteria to metazoan zooplankton (size class cutoffs varied slightly between regions) and their relationship to net primary production and sinking particle flux. Slopes of the normalized biomass size spectra...

Beyond transfer learning: Leveraging ancillary images in automated classification of plankton

Thu, 18 Jun 2026 00:00:00 +0000

Abstract We assess whether a supervised machine learning algorithm, specifically a convolutional neural network (CNN), achieves higher accuracy on planktonic image classification when including non‐plankton and ancillary plankton during the training procedure. We focus on the case of optimizing the CNN for a single planktonic image source, while considering ancillary images to be plankton images from other instruments. We conducted two sets of experiments with three different types of plankton images (from a Zooglider , Underwater Vision Profiler 5, and Zooscan), and our results held across all three image types. First, we considered whether single‐stage transfer learning using non‐plankton images was beneficial. For this assessment, we used ImageNet images and the 2015 ImageNet contest‐winning model, ResNet‐152. We found increased accuracy using a ResNet‐152 model pretrained on ImageNet, provided the entire network was retrained rather than retraining only the fully connected...

Influences of Dispersal and Environmental Selection on Zooplankton Distributions Across the Upper 1000 m of the North Pacific

Thu, 18 Jun 2026 00:00:00 +0000

ABSTRACT Aim Test the response of mesopelagic zooplankton community composition and distributional ranges to dispersal potential and environment, in comparison with the epipelagic zooplankton community. Location Epipelagic (0–200 m) and mesopelagic (200–1000 m) depth zones of the North Pacific Ocean. Taxon Multicellular zooplankton. Methods Metabarcoding of two molecular markers (18S and COI) in combination with a global ocean circulation model, analysed by General Dissimilarity Modelling. Results We found no significant difference in beta‐diversity across three depth strata (0–200, 200–500, and 500–1000 m), calculated from the nMDS dispersion of samples within each stratum. Similarity in beta‐diversity within the three depth strata indicates that epipelagic and mesopelagic zooplankton communities have similar levels of spatial turnover in species composition despite differences in the magnitude of environmental gradients and dispersal potential. There were no differences...

Disturbance ecology in a pelagic upwelling biome: Lagrangian frameworks for studying succession

Thu, 18 Jun 2026 00:00:00 +0000

Abstract Disturbance ecology is underdeveloped in marine pelagic ecosystems relative to terrestrial and aquatic benthic habitats, in part because, when measured relative to a fixed location, postdisturbance recovery involves the advection of entire communities in addition to biotic interactions. A Lagrangian frame-of-reference perspective alleviates this issue. Using results from the California Current Ecosystem, we highlight three approaches: in situ Lagrangian, synthetic Lagrangian, and simulated Lagrangian studies. Within a Lagrangian context, extratropical marine heatwaves and El Niños represent press disturbances or alterations to the disturbance regime. Individual upwelling events are more appropriately viewed as pulse disturbances. Upwelling disturbances stimulate rapid growth of pioneer species (diatoms), with herbivores (copepods) lagging these blooms by approximately 3 weeks. The climax community is an assemblage of small low-nutrient specialists with high Shannon diversity....

Elucidating the Role of Marine Benthic Carbon in a Changing World

Thu, 4 Jun 2026 00:00:00 +0000

Abstract The ocean plays a major role in controlling atmospheric carbon at decadal to millennial timescales, with benthic carbon representing the only geologic‐scale storage of oceanic carbon. Despite its importance, detailed benthic ocean observations are limited and representation of the benthic carbon cycle in ocean and Earth system models (ESMs) is mostly empirical with little prognostic capacity, which hinders our ability to properly understand the long‐term evolution of the carbon cycle and climate change‐related feedbacks. The Benthic Ecosystem and Carbon Synthesis (BECS) working group, with the support of the US Ocean Carbon & Biogeochemistry Program (OCB), identified key challenges limiting our understanding of benthic systems, opportunities to act on these challenges, and pathways to increase the representation of these systems in global modeling and observational efforts. We propose a set of priorities to advance mechanistic understanding and better quantify the...

CMIP7 data request: Earth system priorities and opportunities

Thu, 14 May 2026 00:00:00 +0000

Abstract. This paper presents a comprehensive overview of the Coupled Model Intercomparison Project Phase 7 (CMIP7) request for data pertaining to Earth systems science, and provides justification for the resources needed to produce this data. Topics within the CMIP7 Earth System (CMIP7-ES) theme centre around tracking of flows of energy, carbon, water and other fluxes across domains, and constraining feedbacks between these cycles and the climate system. These topics are summarized in this paper as scientific “opportunities” describing specific model intercomparison experiments and use cases for next-generation Earth System Model (ESM) output. These opportunities were submitted by modelling groups and scientific consortia following an extended public consultation process. Contained within each opportunity are requests for groups of Climate & Forecasting (CF) variables, which are bundled into variable groups representing all data required to address...

STREAMS guidelines: standards for technical reporting in environmental and host-associated microbiome studies

Wed, 6 May 2026 00:00:00 +0000

The interdisciplinary nature of microbiome research, coupled with the generation of complex multi-omics data, makes knowledge sharing challenging. The Strengthening the Organization and Reporting of Microbiome Studies (STORMS) guidelines provide a checklist for the reporting of study information, experimental design and analytical methods within a scientific manuscript on human microbiome research. Here, in this Consensus Statement, we present the standards for technical reporting in environmental and host-associated microbiome studies (STREAMS) guidelines. The guidelines expand on STORMS and include 67 items to support the reporting and review of environmental (for example, terrestrial, aquatic, atmospheric and engineered), synthetic and non-human host-associated microbiome studies in a standardized and machine-actionable manner. Based on input from 248 researchers spanning 28 countries, we provide detailed guidance, including comparisons with STORMS, and case studies that demonstrate...

Correction: A microbial survey of the International Space Station (ISS)

Tue, 21 Apr 2026 00:00:00 +0000

[This corrects the article DOI: 10.7717/peerj.4029.].

A Curious Marine Insect, Hermatobates

Mon, 16 Mar 2026 00:00:00 +0000

A Curious Marine Insect, Hermatobates

The Malayan Pond-Skaters

Wed, 11 Mar 2026 00:00:00 +0000

The Malayan Pond-Skaters

An Explicit Test of Kill the Winner: Protistan Grazing and Phage Lysis Differentially Impact Fast-Growing Bacterial Taxa in the Coastal Antarctic.

Tue, 17 Feb 2026 00:00:00 +0000

Protists and bacteriophages exert top-down control on bacterial populations. Previous work in the coastal Antarctic demonstrates the potential for intra-seasonal variability of this top-down control driven by the extreme seasonal contrast in bacterial growth rates. We evaluated whether predators kill the winner wherein protists and phages preferentially impact the most abundant members of bacterial assemblages over an austral summer with weekly dilution experiments. Seawater from 10 m was divided into two serial dilutions with either 0.2 μm (to evaluate protist grazing) or 30 kDa (to evaluate protist grazing and lysis from bacteriophage) filtered water. We observed strong intra-seasonal change of bacteriophage and protistan contributions to mortality. A comparison of activity per ASV from amplicon sequencing over our dilution experiments to a predicted minimal doubling time indicates that kill the winner is occurring during the top-down control of only a few bacteria. As not all...

Incorporation of Cadmium into Drosophila

Sat, 7 Feb 2026 00:00:00 +0000

The purpose of this study was to determine the toxicity tolerance of Drosophila to cadmium in order to obtain flies with a high Cd body burden. CdCl₂ was added in various concentrations to the larval rearing medium. Development was normal in media containing less than 10²ug/g Cd (wet wt). Adult flies reared on a medium with 31 ug/g Cd (dry wt) contained an average of 73 ug/g Cd (dry wt). Much of the Cd incorporated into the body of the adult fly was located in the soft tissues and the haemolymph; only negligible amounts were found in the cuticle.

A New Rheumatobates from Costa Rica (Hemiptera: Gerridae)

Fri, 30 Jan 2026 00:00:00 +0000

The water strider described here was found in a mangrove swamp. The name is published so that it will be available for a forthcoming work on marine insects.

(Rheumatobates ornatus, n. sp.)

A New species of Hermatobates (Hemiptera: Heteroptera)

Fri, 30 Jan 2026 00:00:00 +0000

Hermatobates is a genus of rarely collected and little known marine insects. The first species, H. haddoni Carpenter was described in 1892. Several additional species were described subsequently (Coutière and Martin, 1901a, 1901b; China, 1956, 1957; Herring, 1965) and they were all assigned to the Gerridae although Matsuda (1960), in his review of the World Gerridae, excluded Hermatobates from that family. The status of this genus is thus still debatable; it will be discussed elsewhere (Andersen, Cheng & Polhemus, in preparation). A review of the relevant literature, with a list of the known species, their distributions and their biology, was published by Cheng (1976).

A Simple emergence trap for small insects

Thu, 29 Jan 2026 00:00:00 +0000

A Simple emergence trap for small insects

Cooperative Acoustic Monitoring of North Pacific Right Whales

Thu, 22 Jan 2026 00:00:00 +0000

Cooperative Acoustic Monitoring of North Pacific Right Whales

Acoustic Monitoring for Killer Whales in the Bering Sea

Thu, 22 Jan 2026 00:00:00 +0000

Acoustic Monitoring for Killer Whales in the Bering Sea

Studies on the Biology of the Gerridae (Hem., Heteroptera) II. The Life History of Metrocoris Tenuicornis Esaki

Thu, 22 Jan 2026 00:00:00 +0000

Studies on the Biology of the Gerridae (Hem., Heteroptera) II. The Life History of Metrocoris Tenuicornis Esaki

Studies on the Biology of the Gerridae (Hem., Heteroptera) I. Observations on the Feeding of Limnogonus Fossarum (F.)

Thu, 22 Jan 2026 00:00:00 +0000

Studies on the Biology of the Gerridae (Hem., Heteroptera) I. Observations on the Feeding of Limnogonus Fossarum (F.)

Observations of Sperm Whale Sounds from Great Depth

Thu, 22 Jan 2026 00:00:00 +0000

Observations of Sperm Whale Sounds from Great Depth

Skaters of the Seas – comparative ecology of nearshore and pelagic Halobates species (Hemiptera: Gerridae), with special reference to Japanese species

Sat, 17 Jan 2026 00:00:00 +0000

Skaters of the Seas – comparative ecology of nearshore and pelagic Halobates species (Hemiptera: Gerridae), with special reference to Japanese species

HALOBATES (Heteroptera: Gerridae) from the Seas Around Nosy Be, Magalasy

Sat, 17 Jan 2026 00:00:00 +0000

Three species are noticed: H. flaviventris, collected in light-samples at night on the continental shelf and slope; H. micans, collected on the shelf around Nosy Be, and in the Indian Ocean between north-Madagascar and equator; H. germanus collected off Nosy Be, generally not far from the continental slope. Almost all are sampled in the wet season (mai to november). Developmental stages and sex are identified.

INSECTA - Hemiptera: Heteroptera Gerridae Genus Halobates

Fri, 16 Jan 2026 00:00:00 +0000

INSECTA - Hemiptera: Heteroptera Gerridae Genus Halobates

Scholarly discussion of issues raised in Paulin's 1995 article: Electroreception and the Compass Sense of Sharks

Thu, 8 Jan 2026 00:00:00 +0000

Scholarly discussion of issues raised in Paulin's 1995 article: Electroreception and the Compass Sense of Sharks

Genome-resolved biogeography of Phaeocystales, cosmopolitan bloom-forming algae

Wed, 10 Dec 2025 00:00:00 +0000

Phaeocystales, comprising the genus Phaeocystis and an uncharacterized sister lineage, are nanoplanktonic haptophytes widespread in the global ocean. Several species form mucilaginous colonies and influence key biogeochemical cycles, yet their underlying diversity and ecological strategies remain underexplored. Here, we present new genomic data from 13 strains, including three high-quality reference genomes (N50 > 30 kbp), and integrate previous metagenome-assembled genomes to resolve a robust phylogeny. Divergence timing of P. antarctica aligns with Miocene cooling and Southern Ocean isolation. Genomic traits reveal metabolic flexibility, including mixotrophic nitrogen acquisition in temperate waters and gene expansions linked to polar nutrient adaptation. Concordantly, transcriptomic comparisons between temperate and polar Phaeocystis suggest Southern Ocean populations experience iron and B12 limitation. We also identify signatures of horizontal gene transfer and endogenous...

Green genes from blue greens: challenges and solutions to unlocking the potential of cyanobacteria in drug discovery

Tue, 9 Dec 2025 00:00:00 +0000

Cyanobacteria are prolific producers of biologically active compounds that are important in influencing ecology, behavior of interacting organisms, and as leads in drug discovery efforts. Here we discuss the challenges faced by all natural product researchers, especially those that focus on cyanobacteria, and then describe progress that has been made in these areas. We also propose some solutions, paths forward, and thoughts for consideration on these challenges.

How are the impacts of climate change on pesticide use incorporated into policy and regulation? A case of almond production in Fresno, California.

Mon, 8 Dec 2025 00:00:00 +0000

How are the impacts of climate change on pesticide use incorporated into policy and regulation? A case of almond production in Fresno, California.

Cadmium and Other Heavy Metals in Sea-Skaters (Gerridae: Halobates, Rheumatobates)

Fri, 5 Dec 2025 00:00:00 +0000

Exceptionally high concentrations of Cd (100 to 200 ppm dry weight) were found in samples of Halobates collected off Baja California. In contrast, no detectable Cd was found in Rheumatobates collected from mangrove lagoons in the Gulf of California. Concentrations of five other heavy metals in the two marine insects are also presented.

Ocean conditions drive interannual variability in juvenile albacore tuna (Thunnus alalunga) muscle energy content in the California Current System

Fri, 5 Dec 2025 00:00:00 +0000

Juvenile albacore tuna (Thunnus alalunga) undertake long migrations across the North Pacific that they fuel by feeding in the California Current System (CCS) during the summer. The CCS is a highly dynamic system, which can lead to differences in foraging success that may be indicated by differences in body condition. Assessed through stomach content analysis, albacore diet composition by mean proportional weight showed high interannual variability including some years characterized by large increases in consumption of anchovy (2011 = 81%, 2017, 2022) and sardine (Sardinops sagax, 2022). We used a generalized additive model (GAM) to investigate the impact of albacore length, month of collection, diet composition, and environmental conditions on albacore muscle energy content. Two proxies for muscle energy content, the carbon to nitrogen ratio (C:N) and ash free dry weight (AFDW), were positively but weakly correlated. Albacore C:N increased with month, body size, and upwelling...

Osmolyte chemical diversity in Lingulaulax polyedra red tides: a critical overlooked factor to respiratory irritations?

Thu, 4 Dec 2025 00:00:00 +0000

The detrimental effects on human health sometimes observed during blooms of Lingulaulax polyedra have been formerly attributed to the yessotoxin analogs this species produces. In this paper we show that natural concentrations of yessotoxin analogs present in seawater and sea spray aerosols during an unprecedented L. polyedra bloom in 2020 in Southern California did not induce inflammation in mammal macrophage cells, questioning the role played by yessotoxin in causing respiratory irritations. This bloom was associated with unprecedented levels of particulate dimethylsulfoniopropionate (2.74 ± 1.63 to 10.11 ± 1.39 µM), gonyol and several new structural analogs ofgonyol . We profiled the metabolic content of dinoflagellate cells and recorded increasing amounts of quaternary amines of the betaine family (carnitine, actinin, ectoine) as the bloom progressed. Being precursors of sulfur and nitrogenous small volatile compounds, we hypothesize that, in addition to their recognized role...

Extremophile hotspots linked to containerized industrial waste dumping in a deep-sea basin

Thu, 20 Nov 2025 00:00:00 +0000

Decaying barrels on the seafloor linked to DDT contamination have raised concerns about the public health implications of decades old industrial waste dumped off the coast of Los Angeles. To explore their contents, we collected sediment cores perpendicular to five deep-sea barrels. The concentration of DDT and its breakdown products were highly elevated relative to control sites yet did not vary with distance from the barrels, suggesting that they were not associated with the contamination. Sediment cores collected through white halos surrounding three barrels were enriched in calcite and had elevated pH. The associated microbial communities were low diversity and dominated by alkalophilic bacteria with metagenome-assembled genomes adapted to high pH. A solid concretion sampled between a white halo and barrel was composed of brucite, a magnesium hydroxide mineral that forms at high pH. Based on these findings, we postulate that leakage of containerized alkaline waste triggered...

Halobates from the Coastal Water of China

Wed, 19 Nov 2025 00:00:00 +0000

Article is in Chinese, Abstract in English is included below and at the end of the article.

Little is known about the Halobates around the coasts of China. This study is based on samples collected from Bohai Sea, East China Sea and South China Sea.

Three species of oceanic Halobates, H. micans, H. sericeus and H. germanus, were collected from the East China Sea, but H. germanus was found in the South China Sea samples. Samples from Bohai Sea consisted of land insects blown out to sea. Adults as well as nymphs of all three Halobates species were collected. The biology and adaptations of these unique oceanic insects are discussed.

Ocean Striders from Melanesia (Hemiptera: Gerridae, Halobates SPP.)

Thu, 13 Nov 2025 00:00:00 +0000

The Halobates samples collected during the cruises "Bora", "Saint Vincent" and "Cyclone" were identified to species, sex and developmental stage. A list of stations from which each species was collected is presented, together with a map of their localities. A brief discussion on the distribution and biology of each species is appended.

Complete Species Phylogeny of the Marine Midge Pontomyia (Diptera:Chironomidae) Reveals a Cosmopolitan Species and a New Synonym

Tue, 4 Nov 2025 00:00:00 +0000

Pontomyia (Diptera: Chironomidae) is an exclusively marine and flightless insect genus with four described species from the Indo-Pacific and one undescribed taxon known only by its larvae, pupal skins and females from the western Atlantic. A previous study of relationships among three of the Indo-Pacific species reported each of them to be monophyletic, with high genetic diversity within P. natans Edwards, the type species, and P. pacifica Tokunaga. The evolutionary affinities of the Australian endemic P. cottoni Womersley that resembles P. natans, as well as the putative Atlantic species are hitherto undetermined. A complete molecular phylogeny of the genus based on two nuclear and two mitochondrial DNA markers indicates that P. cottoni and a Puerto Rican (Atlantic) larval population are nested within the P. natans clade. Furthermore, P. natans and P. cottoni are inseparable in all morphological characters used previously to distinguish them. Therefore, we synonymize...

Phytoplankton dynamics in nearshore regions of the western Antarctic Peninsula in relation to a variable frontal zone in the Gerlache Strait

Tue, 28 Oct 2025 00:00:00 +0000

The Gerlache Strait is a narrow channel that separates the western coast of the Antarctic Peninsula (WAP) from the Palmer Archipelago. This area is characterized by the presence of interconnected fjords, bays, islands, and channels that serve as a refuge for megafauna during summer. Through the framework of FjordPhyto – a citizen science collaboration with the International Association of Antarctica Tour Operators (IAATO) vessels – we assessed phytoplankton biomass and composition in surface waters of six under-explored nearshore areas connected to the Gerlache Strait (between 64° and 65° S) during three consecutive seasons, from November to March (2016–2019). During the first two seasons, we found significant differences in the phytoplankton community distribution and successional patterns to the north and south of the sampling area; the greatest differences were evidenced mainly in the months of high biomass, December and January. During December, cryptophytes bloomed in the...

An undescribed species within the Gymnodinium sensu stricto group found responsible for an exceptional bloom in the Southern Ocean

Tue, 28 Oct 2025 00:00:00 +0000

Naked dinoflagellates are a regular component of the Antarctic phytoplankton but remain poorly studied. In December 2016, the first massive bloom (9.5 × 10⁶ cells · L^-1) of small (~15 μm) naked dinoflagellates was recorded in the western Antarctic Peninsula. To identify these organisms, we performed Illumina next-generation sequencing analysis on field samples to obtain genetic information (SSU rDNA 18SV9 and 16SV4-V5). In addition, we performed polymerase chain reaction (PCR) amplification and Sanger sequencing using dinoflagellate-specific primers (LSU rDNA D1-D3 and ITS/5.8S), as well as traditional light and scanning electron microscopy observations. Phylogenetic analyses revealed that these organisms belonged to the Gymnodinium sensu stricto group and may represent an undescribed species. These analyses also indicated that the observed organisms were closely related to the species Gymnodinium dorsalisulcum, G. impudicum, Barrufeta bravensis, and B. resplendens,...

Can a citizen science project enrich travellers’ experience in Antarctica? Case study of a preliminary evaluation of the FjordPhyto project

Tue, 28 Oct 2025 00:00:00 +0000

Expedition cruise vessels travelling to Antarctica offer several educational opportunities, with Citizen Science (CS) projects being the most prominent way to engage participants in polar science. FjordPhyto is a CS project where travellers onboard expedition cruise vessels gather data and samples for five months (from November to March) during the Antarctic summer season to help researchers understand changes in microalgae communities in response to melting glaciers. Since its inception in 2016, FjordPhyto has involved over 8,000 Antarctic travellers. To understand travellers’ perceptions engaging with the program during its first two years, 81 voluntary feedback surveys were collected from participants during 2017–2018 and 2018–2019 seasons. When analysing open-ended questions, three main themes associated with participant experience emerged: educational, enjoyable, and motivational. Results showed that ‘educational’ was the most frequent category in responses when describing...

Population Genomics Reveals Panmixia in Pacific Sardine (Sardinops sagax) of the North Pacific

Fri, 12 Sep 2025 00:00:00 +0000

The spatial structure and dynamics of populations are important considerations when defining management units in organisms that are harvested as natural resources. In the Eastern Pacific, Pacific Sardine range from Chile to Alaska, the northernmost state of the United States (U.S.), and once supported an expansive and productive fishery. Along its North American range, it is hypothesized to comprise three subpopulations: a northern and southern subpopulation, which primarily occur off the coast of the U.S. and Baja California, Mexico (M.X.), respectively, and a third in the Gulf of California, M.X. We used low coverage whole genome sequencing to generate genotype likelihoods for millions of SNPs in 317 individuals collected from the Gulf of California, M.X., to Oregon, U.S., to assess population structure in Pacific Sardine. Differentiation across the genome was driven by variation at several putative chromosomal inversions ranging in size from ~21 MB to 0.89 MB, although none...

Seasonal changes in physical oceanography modulate cetacean predator-prey dynamics in the San Diego Trough

Thu, 28 Aug 2025 00:00:00 +0000

In marine ecosystems, cetaceans are large mobile predators that depend on maximizing foraging efficiency. Their presence within a habitat can therefore be strongly related to the modulation of local prey by oceanographic conditions. Understanding how cetaceans are impacted by prey responses to the physical environment is challenging due to the difficulty of collecting presence data of cetaceans and their prey over long, comparable time periods. We used passive and active acoustic recordings collected from moorings within the San Diego Trough, along with physical oceanographic sampling (i.e. in situ, satellite-derived, and ocean general circulation model measurements), to elucidate relationships between cetaceans, their prey, and the physical environment. Our results show that the predator-prey dynamics of some cetaceans within the San Diego Trough are influenced by seasonal changes in the physical oceanographic conditions and processes that shape their prey resources. Specifically,...

Cyanobacteria Join the Kahalalide Conversation: Genome and Metabolite Evidence for Structurally Related Peptides

Thu, 28 Aug 2025 00:00:00 +0000

Kahalalide F is a cyclic depsipeptide with notable anticancer properties, initially discovered from the green alga Bryopsis sp. and its molluscan predator Elysia rufescens. Recent studies have pinpointed a bacterial endosymbiont of the green alga, Candidatus Endobryopsis kahalalidefaciens, as the true producer of kahalalide F. In the present work, we characterize a closely related kahalalide F analog, kahalalide Z₅, from the marine cyanobacterium Limnoraphis sp. collected in the Las Perlas Islands, Panama, and propose the structures of several related compounds by detailed MS analysis. To uncover novel metabolites and prioritize them for targeted isolation from this organism, we employed a robust metabolomics strategy combining LC-MS/MS with SMART NMR and DeepSAT, artificial intelligence platforms trained to infer chemical structures from ¹H-¹³C HSQC NMR data. This integrated approach annotated a compound with structural...

Open Ocean Versus Upwelling Regimes: Air‐Sea CO2 Fluxes and pCO2 Inter‐Annual Variability in the Southern California Current System

Thu, 28 Aug 2025 00:00:00 +0000

Abstract Two moorings equipped with autonomous air‐sea CO 2 instrumentation located in the Southern California Current System were used to examine the seasonal and interannual variability of the surface partial pressure of carbon dioxide in seawater ( p CO 2,sw ) and the air‐sea CO 2 flux between 2008 and 2022. These two moorings are in two distinct oceanographic regimes: offshore, centered in the California Current (CCE1), and nearshore within the coastal upwelling regime (CCE2). The offshore seasonal cycles of the surface p CO 2,sw and CO 2 flux are driven by sea surface temperature (SST) seasonality and at the nearshore site by dissolved inorganic carbon (DIC) concentration changes linked with seasonal upwelling. The resulting net annual CO 2 flux at CCE1 is −0.52 molC m −2 year −1 (sink), while at CCE2, the best estimate for the long‐term CO 2 flux mean is 0.23 molC m −2 year −1 (source). The interannual variability at the offshore site is mainly controlled by...

Assessment of Submarine Groundwater Discharge (SGD) as a Source of Dissolved Radium and Nutrients to Moorea (French Polynesia) Coastal Waters

Mon, 11 Aug 2025 00:00:00 +0000

Previous work has documented large fluxes of freshwater and nutrients from submarine groundwater discharge (SGD) into the coastal waters of a few volcanic oceanic islands. However, on the majority of such islands, including Moorea (French Polynesia), SGD has not been studied. In this study, we used radium (Ra) isotopes and salinity to investigate SGD and associated nutrient inputs at five coastal sites and Paopao Bay on the north shore of Moorea. Ra activities were highest in coastal groundwater, intermediate in coastal ocean surface water, and lowest in offshore surface water, indicating that high-Ra groundwater was discharging into the coastal ocean. On average, groundwater nitrate and nitrite (N + N), phosphate, ammonium, and silica concentrations were 12, 21, 29, and 33 times greater, respectively, than those in coastal ocean surface water, suggesting that groundwater discharge could be an important source of nutrients to the coastal ocean. Ra and salinity mass balances...

Life History and Biology of the Riffle Bug Rhagovelia obesa Uhler (Heteroptera: Veliidae) in Southern Ontario

Mon, 4 Aug 2025 00:00:00 +0000

The life history of Rhagovelia obesa (Heteroptera: Veliidae) was investigated using field collected and laboratory reared material. The nymphal instars and adults are described and figured. This is the first life-history study of Rhagovelia or its related genera Tetraripis and Trochopus. These genera together have almost a worldwide distribution and are characterized by a unique swimming plume beating underwater. Four nymphal instars occur instead of the usual five. The overwintering stage is the egg, another unusual feature for aquatic Hemiptera. The site(s) of egg laying have not been located. For the first time Rhagovelia has been raised in the laboratory from first instar to adult.

Link to article from publisher: https://cdnsciencepub.com/doi/10.1139/z71-067

Potential impacts of marine carbon dioxide removal on ocean oxygen

Thu, 17 Jul 2025 00:00:00 +0000

Abstract: Global warming is a main cause for current ocean deoxygenation. A deployment of marine carbon dioxide removal (CDR) for mitigating global warming could therefore also be viewed as a measure for mitigating ocean deoxygenation if, and only if, the respective CDR measure itself does not lead to a larger oxygen loss than the reduction in atmospheric CO2 would prevent. We here review the current state of knowledge regarding the potential impacts of various marine CDR (mCDR) options onto ocean oxygen, a key ocean state variable and an essential element for all higher forms of marine life. Using results from global model simulations, we show that biotic approaches, such as ocean fertilization, macroalgae cultivation and sinking, and placement of organic matter that is prone to remineralization, can lead to a loss in seawater dissolved oxygen that is 4–40 times larger than the oxygen gain that would result from the CDR-induced reduction in global warming only....

Deep Fjords Are Excellent Natural Infrastructure for Climate Impact Studies

Thu, 17 Jul 2025 00:00:00 +0000

ABSTRACT: Fjords provide valuable research opportunities for marine scientists. They are excellent natural infrastructure for climate impact studies associated with hypoxic episodes and consequences for mesopelagic and deep‐sea ecosystems involving oceanographic circulation processes and basin water renewals. Repeated sampling from the same populations is possible, making fjords excellent systems for developing time series of data for climate impact studies. We provide an overview of the 14 years of data from Norwegian West Coast fjords, focusing on Masfjorden, and report major findings from Oslofjorden in Eastern Norway, exhibiting recurrent hypoxia in the basin waters. We document that the oxygen levels in Masfjorden decreased rapidly by over 60% at 450 m depth in < 8 years, which is much faster than the average rate of deoxygenation in the global ocean. We also discuss the increase in the deep‐sea and low‐light‐adapted coronate jellyfish Periphylla periphylla in view of...

Illuminating deep-sea considerations and experimental approaches for mCDR proposals

Thu, 17 Jul 2025 00:00:00 +0000

Illuminating deep-sea considerations and experimental approaches for mCDR proposals

Methane-powered sea spiders: Diverse, epibiotic methanotrophs serve as a source of nutrition for deep-sea methane seep Sericosura

Thu, 17 Jul 2025 00:00:00 +0000

Methane seeps harbor uncharacterized animal-microbe symbioses with unique nutritional strategies. Three undescribed sea spider species (family Ammotheidae; genus Sericosura) endemic to methane seeps were found along the eastern Pacific margin, from California to Alaska, hosting diverse methane- and methanol-oxidizing bacteria on their exoskeleton. δ¹³C tissue isotope values of in situ specimens corroborated methane assimilation (-45‰, on average). Live animal incubations with ¹³C-labeled methane and methanol, followed by nanoscale secondary ion mass spectrometry, confirmed that carbon derived from both compounds was actively incorporated into the tissues within five days. Methano- and methylotrophs of the bacterial families Methylomonadaceae, Methylophagaceae and Methylophilaceae were abundant, based on environmental metagenomics and 16S rRNA sequencing, and fluorescence and electron microscopy confirmed dense epibiont aggregations on the sea spider...

Why aquatic deoxygenation belongs in the planetary boundary framework

Thu, 17 Jul 2025 00:00:00 +0000

Why aquatic deoxygenation belongs in the planetary boundary framework

Nighttime-Accentuated Heatwaves in California: An Application of Spatial Epidemiology to Inform Policy

Tue, 15 Jul 2025 00:00:00 +0000

Extreme heat events (EHEs) are the deadliest climate-related hazard in the United States, with California bearing the highest burden of heat-related hospitalizations. While daytime heat is dangerous, climate change is increasingly driving extreme nighttime temperatures, with minimum temperatures rising more rapidly than maximums. Yet most adaptation policies focus solely on daytime conditions, overlooking the distinct health risks of sustained overnight heat. This mixed-methods study integrates spatial epidemiological mapping with stakeholder interviews to assess the health impacts and policy challenges associated with nighttime-accentuated EHEs in California. Quantitative findings show that hospitalizations linked to minimum temperature EHEs were spatially diffuse but concentrated in marginalized communities, particularly in the Southern Deserts and coastal urban areas. Interviews with state, county, and NGO stakeholders highlighted systemic gaps in policy attention, infrastructure...

Atmospheric Rivers and West Antarctic Sea Ice Variations

Tue, 15 Jul 2025 00:00:00 +0000

Atmospheric rivers (ARs) are intense, narrow corridors of water vapor transport that play a critical role in the exchange of heat and moisture between the atmosphere and the ocean. In the Antarctic, ARs are capable of carrying large amounts of latent and sensible heat to otherwise cold and dry environments, with immense impacts on surface energy budgets and sea ice dynamics. This study investigates the relationship between extreme turbulent heat flux events defined as the top 5% of latent and sensible heat flux anomalies and sea ice variability in the West Antarctic Peninsula during January and June, representing austral summer and winter, respectively. Events are classified as “AR” and “non-AR” using the tARget version 4 AR catalog. Using ERA5 reanalysis data, we analyze sea ice concentration alongside surface temperature, wind speed, and integrated vapor transport (IVT). Our findings aim to clarify the distinct roles that ARs play in modulating Antarctic sea ice, especially...

Multi‐Trophic Level Responses to Marine Heatwave Disturbances in the California Current Ecosystem

Mon, 14 Jul 2025 00:00:00 +0000

Marine heatwaves (MHWs) caused by multiple phenomena with days to months duration are increasingly common disturbances in ocean ecosystems. We investigated the impacts of MHWs on pelagic communities using spatially resolved time-series of multiple trophic levels from the Southern California Current Ecosystem. Indices of phytoplankton biomass mostly declined during MHWs because of reduced nutrient supply (excepting Prochlorococcus) and were generally more sensitive to marine heatwave intensity than duration. By contrast, mesozooplankton (as estimated by zooplankton displacement volume) were somewhat more strongly correlated with MHW duration than intensity. Zooplankton anomalies were also positively correlated with fucoxanthin (diatom) anomalies, highlighting possible bottom-up influences during MHWs. Mobile consumers (forage fish) showed more complex responses, with fish egg abundance declining during MHWs but not correlating with any MHW characteristics. Our findings provide...

Assessing Ecological Outcomes of Blue Carbon Restoration in Australia: A focus on Tasmanian Salt Marshes

Mon, 14 Jul 2025 00:00:00 +0000

Tidal salt marshes are among Australia’s most important blue carbon ecosystems, offering essential services such as carbon sequestration, coastal protection, and critical habitat for fish and wildlife. Yet many remain degraded, and restoration efforts are constrained by limited guidance on how to effectively monitor ecological outcomes. This capstone project evaluates the utility of imaging sonar as a non-invasive tool to assess fish abundance, behavior, and habitat use in restored tidal wetlands across Tasmania.

The study contributes to the development of a standardized methodology for applying imaging sonar in salt marsh environments—habitats where turbidity and shallow water limit the effectiveness of optical or diver-based surveys. Results show that while imaging sonar is well-suited for detecting fish in these challenging conditions, it must be used alongside traditional gear-based methods, such as pop, fyke, and seine nets, to ensure representative sampling across...

Metagenomic Identification of Brominated Indole Biosynthetic Machinery from Cyanobacteria

Mon, 14 Jul 2025 00:00:00 +0000

Halogenated indole natural products have been isolated from a variety of organisms, including plants, marine algae, marine invertebrates, and bacteria. Aquatic cyanobacteria, in particular, are rich producers of brominated indoles, but their cognate biosynthetic enzymes have only been successfully linked in a limited number of natural products, such as the eagle-killing toxin aetokthonotoxin (AETX). The biosynthetic pathway for AETX involves five enzymes, two of which were previously undescribed due to incomplete annotations as hypothetical proteins. Our recent elucidation of AETX biosynthesis established functions of the two previously unknown proteins as enzymes responsible for tryptophan halogenation (AetF) and nitrile synthesis (AetD). Given their sequence novelty, we queried metagenomic data sets for these two enzymes and identified two new cyanobacterial haloindole biosynthetic gene clusters (BGCs) from marine sediment in Moorea, French Polynesia, and soil-derived samples...

Promiscuity in Nature Extends to Central Protein Biosynthetic Machinery

Mon, 14 Jul 2025 00:00:00 +0000

Thioesters, rather than oxo-esters, can be tolerated and processed during translation to incorporate unnatural monomers.

Storytelling for a Species - The White Abalone Story

Thu, 10 Jul 2025 00:00:00 +0000

The White Abalone (Haliotis sorenseni) is functionally extinct in the wild. The only thing standing between this species and complete extinction is a dedicated group of individuals working tirelessly to save it. In a time of uncertain funding for many disciplines, particularly in science, it is crucial to effectively communicate the efforts of scientists, volunteers, and everyday citizens who are striving to protect a species on the brink of extinction due to human-caused impacts. Storytelling for a Species – The White Abalone Story aims to tell the story of the White Abalone and its recovery efforts, helping to illuminate, illustrate, and educate others about the importance of saving this humble creature.

Please see media created for this project here:

https://youtu.be/bC0xbSREATg?si=...

Stakeholder Valuation of CalCOFI Data usage for Improved Decision Making