Marine Organisms Research Articles

Updated Progress on Polysaccharides with Anti-Diabetic Effects through the Regulation of Gut Microbiota: Sources, Mechanisms, and Structure-Activity Relationships.

Diabetes mellitus (DM) is a common chronic metabolic disease worldwide. The disturbance of the gut microbiota has a complex influence on the development of DM. Polysaccharides are one type of the most important natural components with anti-diabetic effects. Gut microbiota can participate in the fermentation of polysaccharides, and through this, polysaccharides regulate the gut microbiota and improve DM. This review begins by a summary of the sources, anti-diabetic effects and the gut microbiota regulation functions of natural polysaccharides. Then, the mechanisms of polysaccharides in regulating the gut microbiota to exert anti-diabetic effects and the structure-activity relationship are summarized. It is found that polysaccharides from plants, fungi, and marine organisms show great hypoglycemic activities and the gut microbiota regulation functions. The mechanisms mainly include repairing the gut burrier, reshaping gut microbiota composition, changing the metabolites, regulating anti-inflammatory activity and immune function, and regulating the signal pathways. Structural characteristics of polysaccharides, such as monosaccharide composition, molecular weight, and type of glycosidic linkage, show great influence on the anti-diabetic activity of polysaccharides. This review provides a reference for the exploration and development of the anti-diabetic effects of polysaccharides.

Spatio-temporal connectivity and dispersal seasonal patterns in the Adriatic Sea using a retention clock approach

Hydrodynamic features play a key role in determining the dispersal and connectivity of fish populations, especially in highly energetic areas determined by currents, river flow, and meteorologically induced fluctuations. Understanding how species interact with these physical processes is essential for managing vulnerable populations and identifying areas that require effective conservation efforts. This study examines the hydrodynamics that regulate connectivity in the Adriatic Sea, a shallow and semi-enclosed basin that is widely recognized as one of the most important areas in the Mediterranean Sea for protection. A high-resolution hydrodynamic model coupled with a lagrangian tracking module serves as the numerical tool. Lagrangian particles, representing eggs and larvae with typical biological characteristics of generic marine organisms inhabiting the region, are released throughout the basin at different times during a test year to identify the most likely pathways of individual dispersal. The temporal component of connectivity is highlighted using a previously developed retention clock matrix over different larval durations. Seasonality is a critical factor in dispersal, with greater variability and reduced efficiency in winter compared to summer. The potential implications of the results for improved assessment and management of high value marine species in the basin are discussed.

Molecular control of cellulosic fin morphogenesis in ascidians

BackgroundThe tunicates form a group of filter-feeding marine animals closely related to vertebrates. They share with them a number of features such as a notochord and a dorsal neural tube in the tadpole larvae of ascidians, one of the three groups that make tunicates. However, a number of typical chordate characters have been lost in different branches of tunicates, a diverse and fast-evolving phylum. Consequently, the tunic, a sort of exoskeleton made of extracellular material including cellulose secreted by the epidermis, is the unifying character defining the tunicate phylum. In the larva of ascidians, the tunic differentiates in the tail into a median fin (with dorsal and ventral extended blades) and a caudal fin.ResultsHere we have performed experiments in the ascidian Phallusia mammillata to address the molecular control of tunic 3D morphogenesis. We have demonstrated that the tail epidermis medio-lateral patterning essential for peripheral nervous system specification also controls tunic elongation into fins. More specifically, when tail epidermis midline identity was abolished by BMP signaling inhibition, or CRISPR/Cas9 inactivation of the transcription factor coding genes Msx or Klf1/2/4/17, median fin did not form. We postulated that this genetic program should regulate effectors of tunic secretion. We thus analyzed the expression and regulation in different ascidian species of two genes acquired by horizontal gene transfer (HGT) from bacteria, CesA coding for a cellulose synthase and Gh6 coding for a cellulase. We have uncovered an unexpected dynamic history of these genes in tunicates and high levels of variability in gene expression and regulation among ascidians. Although, in Phallusia, Gh6 has a regionalized expression in the epidermis compatible with an involvement in fin elongation, our functional studies indicate a minor function during caudal fin formation only.ConclusionsOur study constitutes an important step in the study of the integration of HGT-acquired genes into developmental networks and a cellulose-based morphogenesis of extracellular material in animals.

Preliminary hazard assessment of a new nature-inspired antifouling (NIAF) agent

A recently synthesized aminated 3,4-dioxygenated xanthone (Xantifoul2) was found to have promising antifouling (AF) effects against the settlement of the macrofouler Mytilus galloprovincialis larvae. Preliminary assessment indicated that Xantifoul2 has reduced ecotoxicological impacts: e.g., being non-toxic to the marine crustacea Artemia salina (<10 % mortality at 50 μM) and showing low bioconcentration factor in marine organisms. In order to meet the EU Biocidal Product Regulation, a preliminary hazard assessment of this new nature-inspired antifouling (NIAF) agent was conducted in this work. Xantifoul2 did not affect the swimming ability of the planktonic crustacean Daphnia magna, the growth of the diatom Phaeodactylum tricornutum, and the cellular respiration of luminescent Gram-negative bacteria Vibrio fischeri, supporting the low toxicity towards several non-target marine species. Regarding human cytotoxicity, Xantifoul2 did not affect the cell viability of retinal human cells (hTERT-RPE-1) and lipidomic studies revealed depletion of lipids involved in cell death, membrane modeling, lipid storage, and oxidative stress only at a high concentration (10 μM). Accelerated degradation studies in water were conducted under simulated sunlight to allow the understanding of putative transformation products (TPs) that could be generated in the aquatic ecosystems. Both Xantifoul2 and photolytic-treated Xantifoul2 in the aqueous matrix were therefore evaluated on several nuclear receptors (NRs). The results of this preliminary hazard assessment of Xantifoul2, combined with the high degradation rates in water, provide strong evidence of the safety of this AF agent under the evaluated conditions, and provide the support for future validation studies before this compound can be introduced in the market.

Marine sulfated glycans inhibit the interaction of heparin with S-protein of SARS-CoV-2 Omicron XBB variant.

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has caused a worldwide COVID-19 pandemic, leading to 6.8million deaths. Numerous variants have emerged since its outbreak, resulting in its significantly enhanced ability to spread among humans. As with many other viruses, SARS‑CoV‑2 utilizes heparan sulfate (HS) glycosaminoglycan (GAG) on the surface of host cells to facilitate viral attachment and initiate cellular entry through the ACE2 receptor. Therefore, interfering with virion-HS interactions represents a promising target to develop broad-spectrum antiviral therapeutics. Sulfated glycans derived from marine organisms have been proven to be exceptional reservoirs of naturally existing HS mimetics, which exhibit remarkable therapeutic properties encompassing antiviral/microbial, antitumor, anticoagulant, and anti-inflammatory activities. In the current study, the interactions between the receptor-binding domain (RBD) of S-protein of SARS-CoV-2 (both WT and XBB.1.5 variants) and heparin were applied to assess the inhibitory activity of 10 marine-sourced glycans including three sulfated fucans, three fucosylated chondroitin sulfates and two fucoidans derived from sea cucumbers, sea urchin and seaweed Saccharina japonica, respectively. The inhibitory activity of these marine derived sulfated glycans on the interactions between RBD of S-protein and heparin was evaluated using Surface Plasmon Resonance (SPR). The RBDs of S-proteins from both Omicrion XBB.1.5 and wild-type (WT) were found to bind to heparin, which is a highly sulfated form of HS. All the tested marine-sourced sulfated glycans exhibited strong inhibition of WT and XBB.1.5S-protein binding to heparin. We believe the study on the molecular interactions between S-proteins and host cell glycosaminoglycans provides valuable insight for the development of marine-sourced, glycan-based inhibitors as potential anti-SARS-CoV-2 agents.

Preparation of PEG-terminated polyurea thin films using vapor deposition polymerization

Antifouling coatings can address the significant challenges faced in water treatment, marine applications, and medical fields owing to the biofouling from proteins, bacteria, and marine organisms. The use of insoluble and non-melting polymers is necessary to improve the physical and chemical durability of antifouling coatings. However, the conventional wet processes for applying these coatings present significant challenges. In this study, we prepared thin films with improved antifouling properties and chemical durability using vapor deposition polymerization. After the co-deposition of isocyanate and amine monomers to form a polyurea film, polyethylene glycol (PEG), with a molecular weight of 600, was deposited to form a PEG-terminated polyurea film. The coverage of PEG was ∼80%, and the amount of protein adsorbed was reduced to ∼30% compared to that on unmodified polyurea. The polymerized polyurea thin films and PEG chemically bonded to polyurea exhibited high chemical resistance.

Nanoplastics impair growth and nitrogen fixation of marine nitrogen-fixing cyanobacteria

Nanoplastics pollution is a growing environmental problem worldwide. Recent research has demonstrated the toxic effects of nanoplastics on various marine organisms. However, the influences of nanoplastics on marine nitrogen-fixing cyanobacteria, a critical nitrogen source in the ocean, remained unknown. Here, we report that nanoplastics exposure significantly reduced growth, photosynthetic, and nitrogen fixation rates of Crocosphaera watsonii (a major marine nitrogen-fixing cyanobacterium). Transcriptomic analysis revealed that nanoplastics might harm C. watsonii via downregulation of photosynthetic pathways and DNA damage repair genes, while genes for respiration, cell damage, nitrogen limitation, and iron (and phosphorus) scavenging were upregulated. The number and size of starch grains and electron-dense vacuoles increased significantly after nanoplastics exposure, suggesting that C. watsonii allocated more resources to storage instead of growth under stress. We propose that nanoplastics can damage the cell (e.g., DNA, cell membrane, membrane-bound transporters, etc.), inhibit N2 and CO2 fixation, and hence lead to nutrient limitation and impaired growth. Our findings suggest the possibility that nanoplastics pollution could reduce the new nitrogen input and hence affect the productivity in the ocean. The impact of nanoplastics on marine nitrogen fixation and productivity should be considered when predicting the ecosystem response and biogeochemical cycling in the changing ocean.

A high throughput method to assess the hypoxia tolerance of abalone based on adhesion duration

To alleviate the economic losses induced by hypoxia, it is useful to accelerate genetic improvement in the aquaculture industry and breed hypoxia-tolerant varieties. An accurate phenotype assessment is fundamental to the study of hypoxia tolerance in marine organisms. In this study, a high-throughput assessment method, termed hypoxia adhesion duration (HYAD), was developed based on the change in the adhesion capacity of abalone under hypoxic exposure. To confirm the viability of the HYAD method, the hypoxia tolerance of Haliotis discus hannai and its hybrid with H. fulgens (H. discus hannai ♀ × H. fulgens ♂) was measured and compared. Enzyme activities associated with antioxidation and apoptosis, such as those of superoxide dismutase (SOD), catalase (CAT), and caspase-8, were detected to characterize the physiological status of abalone before and after the loss of adhesion capacity. The results highlighted greater hypoxia tolerance in hybrid abalone, possibly due to higher antioxidant capacity and cellular protection. The HYAD value increased with thermal acclimation duration (8 and 12 d), decreased with abalone age (9 and 33 months), and was not affected by abalone sex. The HYAD method is high-throughput, accurate, and easy to use, supporting individual and population detection. This method will allow the selection and retention of hypoxia-tolerant abalone individuals and populations for further genetic breeding.

Breathing in danger: Mapping microplastic migration in the human respiratory system

The abundance of air pollutants over the last few years, including the concentration of microplastics, has become an alarming concern across the world. Initially discovered in marine life, these toxic and inflammatory particles have recently been found in human lung tissues. When inhaled, these harmful particles settle down in the lung airways and, over time, lead to respiratory failures. A recent study analyzed the microplastic transport behavior in the mouth–throat airways. However, the knowledge of the microplastic migration in bifurcating tracheobronchial airways is missing in the literature. Therefore, this first-ever study analyzes in detail the transport behavior and settling patterns of microplastic particles of different sizes and shapes at different respiratory intensities in the tracheobronchial lung airways. A numerical technique based on discrete phase modeling is employed to simulate the flow of microplastic particles in a three-dimensional realistic lung geometry. The numerical model results indicate low velocity and turbulence intensity magnitudes with smooth flow in the trachea compared to the airways of left and right lobes, which experience higher velocities and generate secondary vortices. Lower lung lobes are the deposition hotspots for the harmful microplastic particles at a lower flow rate. These hotspots shift to upper lung lobes at a higher flow rate for the same particle size. Moreover, microplastic particle size and shape influence the overall deposition rate in the tracheobronchial lung airways. The results of the current study, including microplastic accumulation regions at different breathing intensities, will contribute to the updated knowledge of pollutant inhalation and facilitate relevant treatment measures.

Extended ozone depletion and reduced snow and ice cover-Consequences for Antarctic biota.

Stratospheric ozone, which has been depleted in recent decades by the release of anthropogenic gases, is critical for shielding the biosphere against ultraviolet-B (UV-B) radiation. Although the ozone layer is expected to recover before the end of the 21st century, a hole over Antarctica continues to appear each year. Ozone depletion usually peaks between September and October, when fortunately, most Antarctic terrestrial vegetation and soil biota is frozen, dormant and protected under snow cover. Similarly, much marine life is protected by sea ice cover. The ozone hole used to close before the onset of Antarctic summer, meaning that most biota were not exposed to severe springtime UV-B fluxes. However, in recent years, ozone depletion has persisted into December, which marks the beginning of austral summer. Early summertime ozone depletion is concerning: high incident UV-B radiation coincident with snowmelt and emergence of vegetation will mean biota is more exposed. The start of summer is also peak breeding season for many animals, thus extreme UV-B exposure (UV index up to 14) may come at a vulnerable time in their life cycle. Climate change, including changing wind patterns and strength, and particularly declining sea ice, are likely to compound UV-B exposure of Antarctic organisms, through earlier ice and snowmelt, heatwaves and droughts. Antarctic field research conducted decades ago tended to study UV impacts in isolation and more research that considers multiple climate impacts, and the true magnitude and timing of current UV increases is needed.

Exploring the Hawaiian Ala Wai Watershed with Zebrafish.

The Ala Wai Canal is an artificial waterway in the tourist district of Waikiki in Honolulu, HI. Originally built to collect runoff from industrial, residential, and green spaces dedicated to recreation, the Ala Wai Canal has since experienced potent levels of toxicity due to this runoff entering the watershed and making it hazardous for both marine life and humans at current concentration, including Danio rerio (zebrafish). A community of learners at educations levels from high school to postbaccalaureate from Oahu, HI was connected through the Consortium for Increasing Research and Collaborative Learning Experiences (CIRCLE) distance research program. This team conducted research with an Investigator and team from Mayo Clinic in Rochester, MN, with the Ala Wai Canal as its primary subject. Through CIRCLE, research trainees sent two 32 oz bottles of Ala Wai- acquired water to a partnered laboratory at the Mayo Clinic in which zebrafish embryos were observed at differing concentrations of the sampled water against a variety of developmental and behavioral assays. Research trainees also created atlases of developmental outcomes in zebrafish following exposure to environmental toxins and tables of potential pesticide contaminants to enable the identification of the substances linked to structural defects and enhanced stress during Ala Wai water exposure experiments.

Exploring Alternatives for Marine Toxicity Testing: Initial Evaluation of Fish Embryo and Mysid Tests.

Current regulations require that toxicity assessments be performed using standardized toxicity testing methods, often using fish. Recent legislation in both the European Union and United States has mandated that toxicity testing alternatives implement the 3Rs of animal research (replacement, reduction, and refinement) whenever possible. There have been advances in the development of alternatives for freshwater assessments, but there is a lack of analogous developments for marine assessments. One potential alternative testing method is the fish embryo toxicity (FET) test, which uses fish embryos rather than older fish. In the present study, FET methods were applied to two marine model organisms, the sheepshead minnow and the inland silverside. Another potential alternative is the mysid shrimp survival and growth test, which uses an invertebrate model. The primary objective of the present study was to compare the sensitivity of these three potential alternative testing methods to two standardized fish-based tests using 3,4-dichloroaniline (DCA), a common reference toxicant. A secondary objective was to characterize the ontogeny of sheepshead minnows and inland silversides. This provided a temporal and visual guide that can be used to identify appropriately staged embryos for inclusion in FET tests and delineate key developmental events (e.g., somite development, eyespot formation, etc.). Comparison of the testing strategies for assessing DCA indicated that: (1) the standardized fish tests possessed comparable sensitivity to each other; (2) the mysid shrimp tests possessed comparable sensitivity to the standardized fish tests; (3) the sheepshead minnow and inland silverside FET tests were the least sensitive testing strategies employed; and (4) inclusion of sublethal endpoints (i.e., hatchability and pericardial edema) in the marine FETs increased their sensitivity. Environ Toxicol Chem 2024;00:1-15. © 2024 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Causes and effects of sampling bias on marine Western Atlantic biodiversity knowledge

AbstractAimKnowledge gaps and sampling bias can lead to underestimations of species richness and distortions in the known distribution of species. The goal of this study is to identify potential gaps and biases in marine organisms sampling at the Western Atlantic Ocean, determine their causes and assess its effect on biodiversity metrics. We tested the potential interference of this bias with the representation of environmental conditions, potentially affecting biodiversity model predictions.LocationWestern Atlantic Ocean.MethodsThis study compiled data of marine species in online and institutional databases. The analysis of sampling effort and bias was conducted by mapping the density of records. A spatial autoregressive model (SAR) was employed to investigate the influence of accessibility as a determinant factor of the sampling bias. We tested whether the effect of the sampling bias could result from environmental bias in the samples, contrasting the environmental variables of the study area with those present in the biodiversity records. We examined the correlation between sampling effort in species richness and endemism.ResultsThe USA has the highest number of records and density of records. There was a low correlation between the vertebrates, invertebrates and algae sample density patterns. Accessibility was identified as one of the main causes of sampling bias. The analysis of environmental bias indicated that the records do not represent all conditions present in the environment. Sampling density showed a strong relationship with endemism and a weaker relationship with species richness.Main ConclusionsWe have identified a strong sampling bias related to ease of access that equally affects vertebrates, invertebrates and algae, resulting in a skewed sampling of the environmental conditions where species occur. Sampling patterns differ among the groups. The intensity of sampling effort significantly impacts measures of richness and endemism, potentially undermining the accurate recognition of real biological diversity patterns.

Antibacterial potential of marine organisms and coastal plants in combating antibacterial resistance: A review

Antibacterial potential of marine organisms and coastal plants in combating antibacterial resistance: A review

Cuvier's beaked whale (Ziphius cavirostris) detection through surface-sourced eDNA: A promising approach for monitoring deep-diving cetaceans

Among cetaceans, the Cuvier’s beaked whale is considered an extreme diver, thus not one of the easiest cetacean species to be studied due to its elusive behaviour and a preference for deep offshore waters. Although dedicated cetacean surveys have increased our knowledge on the distribution of Cuvier’s beaked whales in the Mediterranean Sea, knowledge gaps still remain where the study effort is non-existent. In this context, the use of new molecular methodologies capable of intercepting small traces of DNA left in the environment (eDNA) by marine organisms represents a valid approach to infer species’ occurrence. Moreover, the collection of water from the superficial layer is suitable for targeting marine mammals, as the constraints imposed by their nature implies periodic and frequent surfacing in order to breathe, releasing exhalants rich in their epithelial cells. Therefore, we designed and tested a taxon-specific primer set to infer Cuvier’s beaked whale presence, with the aims of 1) examining the effectiveness of the eDNA technique to detect the presence of a deep-diving cetacean in open waters, using the Cuvier’s beaked whale as case study; 2) providing data on the occurrence of this species within the Canyon of Caprera over a six-months study period and 3) assessing the species presence in adjacent waters in the central northern Mediterranean Sea based on the analysis of samples collected in a Citizen Science campaign. Results from this study demonstrated that superficial waters may retain biological traces of this cetacean despite the fact that it mostly inhabits deep waters. Specifically, this study provides evidence of the regular presence of Cuvier’s beaked whale in the Canyon of Caprera, with a preference for bathymetry in the range of 700–1000 m. Molecular traces’ distribution suggests a potential inshore movement of this species during Fall, which might be related to migration of its cephalopod prey or a shift in prey preferences, although this aspect requires further investigation. Overall, this study showed that the stronger positive signals were recorded in sampling stations located on surfaces above submarine canyon systems, demonstrating the importance of these areas as elective habitats for the Cuvier’s beaked whale, thus the pivotal priority to their conservation.

Defense and Protection of the Marine Coastal Areas and Human Health: A Case Study of Asbestos Cement Contamination (Italy)

Pivotal environmental geology research was carried out in the protected area of Cape Peloro (Messina, NE Sicily, Italy). The main aims were the ascertainment of the presence of Asbestos Cement Materials (ACMs), their mapping, and, consequently, an estimation of the potential risk for human health and marine coastal environments. The beaches surveyed covered 4500 m of coastline. Through high-resolution photographic surveys, over 520 fiber cement fragments were documented on the beaches as well as in beach deposits. The materials, after microscope, SEM-EDS, and FTIR analyses, were found to be composed of Portland cement with chrysotile and crocidolite fibers. Fragments of ACMs showed typical corrugated forms with centimeter-to-decimeter sizes and prevailing well-rounded, platy, and sub-elongate shapes. In a few localities, some fragments were found to be angular or friable. Furthermore, some fragments found on the beach were covered by conspicuous encrustations of marine organisms, testifying to their long staying in shallow-water marine environments. Illicit landfills and abandoned materials were identified in natural sections on the coastal plain. Most of the rounded ACMs were characterized by their surface texture, with mm-size asbestos fibers exposed on the surface due to significant weathering and abrasion. Notably, new fragments appeared after storms. Significant criticisms have been made related to the ACMs, analogously to what was reported for other Italian marine beaches. Possible intervention and reclamation activities cannot limit themselves to removing the fragments on the beach, as fragments are immersed in the coastal sediments at different depths and are also found in the marine deposits. Here, it is underlined that any asbestos removal and reclamation activities, if not designed and based on a multidisciplinary approach and knowledge of local coastal dynamics and the meteo-marine climate, will be very expensive and ineffective.

Ecological potential of giant clams in Ambon Island waters, Eastern Indonesia

Giant clams are protected marine organisms universally, thus information on giant clams is important for management purposes. This research was conducted in July to August 2021 in Morella and Suli, Ambon Island Maluku Province to get information on ecological potential which consist of species composition, density, occurrence frequency and diversity of giant clams. Sample was collected by using linear quadrat transect line. As many as 25 quadrants (10x10m) were used in both locations. Every individual of giant clams found in the quadrant was identified, photographed and counted. There were three species of giant clams found in Morella namely Tridacna crocea, T. maxima, and T. squamosa while four species were found in Suli i.e. those three species mentions earlier and Hippopus Hippopus. Totally, T. crocea had more individuals followed by T. squamosa and then T. maxima while the lesser belonged to H. Hippopus with one individual. Density of giant clams in Morella (428 ind./ha) was much higher than density of giant clams in Suli (48 ind./ha). Giant clams in Morella can be found in 16 - 19 quadrants of 25 quadrants used while in Suli only found in 1 - 6 quadrants. Ecological indexes for diversity, evenness and dominance showed that giant clams in Morella and Suli had moderate diversity, high evenness and low dominance.

Beauty in the beast - Placozoan biodiversity explored through molluscan predator genomics.

The marine animal phylum Placozoa is characterized by a poorly explored cryptic biodiversity combined with very limited knowledge of their ecology. While placozoans are typically found as part of the epibenthos of coastal waters, known placozoan predators, namely small, shell-less sea slugs belonging to the family Rhodopidae (Mollusca: Gastropoda: Heterobranchia), inhabit the interstitium of seafloor sediment. In order to gain further insights into this predator-prey relationship and to expand our understanding of placozoan ecological niches, we screened publicly available whole-body metagenomic data from two rhodopid specimens collected from coastal sediments. Our analysis not only revealed the signatures of three previously unknown placozoan lineages in these sea slug samples but also enabled the assembly of three complete and two partial mitochondrial chromosomes belonging to four previously described placozoan genera, substantially extending the picture of placozoan biodiversity. Our findings further refine the molecular phylogeny of the Placozoa, corroborate the recently established taxonomic ranks in this phylum, and provide molecular support that known placozoan clades should be referred to as genera. We finally discuss the main finding of our study - the presence of placozoans in the sea floor sediment interstitium - in the context of their ecological, biological, and natural history implications.

Historical fragmentation and stepping-stone gene flow led to population genetic differentiation in a coastal seabird.

Understanding the forces that shape population genetic structure is fundamental both for understanding evolutionary trajectories and for conservation. Many factors can influence the geographic distribution of genetic variation, and the extent to which local populations differ can be especially difficult to predict in highly mobile organisms. For example, many species of seabirds are essentially panmictic, but some show strong structure. Pigeon Guillemots (Cepphus columba; Charadriiformes: Alcidae) breed in small colonies scattered along the North Pacific coastline and feed in shallow nearshore waters year-round. Given their distribution, gene flow is potentially lower and population genetic structure is stronger than in most other high-latitude Northern Hemisphere seabirds. We screened variation in the mitochondrial control region, four microsatellite loci, and two nuclear introns in 202 Pigeon Guillemots representing three of five subspecies. Mitochondrial sequences and nuclear loci both showed significant population differences, although structure was weaker for the nuclear loci. Genetic differentiation was correlated with geographic distance between sampling locations for both the mitochondrial and nuclear loci. Mitochondrial gene trees and demographic modeling both provided strong evidence for two refugial populations during the Pleistocene glaciations: one in the Aleutian Islands and one farther east and south. We conclude that historical fragmentation combined with a stepping-stone model of gene flow led to the relatively strong population differentiation in Pigeon Guillemots compared to other high-latitude Northern Hemisphere seabird species. Our study adds to growing evidence that Pleistocene glaciation events affected population genetic structure not only in terrestrial species but also in coastal marine animals.

Enhancing green sea turtle (Chelonia mydas) conservation for tourists at Little Liuqiu island, Taiwan: Application of deep learning algorithms

Observing marine life has emerged as a pivotal catalyst for the growth of the Blue Economy. Yet, overzealous and recurrent observations may exert undue stress on marine creatures, thereby complicating the sustainable management of marine assets. After the easing of Covid-19 pandemic restrictions, a notable influx of tourists to Little Liuqiu Island, Taiwan puts considerable stress on its green sea turtle population. This surge intensified incidents of illegal harassment, triggering concerns from both the local community and administrative bodies. The prevailing challenge is to ensure tourists observe these turtles with respect, refraining from behaviors such as touching or pursuing them. Addressing this, our study harnesses deep learning algorithms to equip ecotourism operators and tourists with tools to detect green sea turtles across diverse coastal terrains, reinforcing conservation efforts. Our analysis scrutinized object detection AI models, namely YOLOv3, YOLOv5s, and YOLOv5l. Fieldwork was undertaken on the island to gather ample training images, capturing elusive green sea turtles in various settings, from coastline strolls to drone imagery. Supplemental images sourced from local social media platforms were later added. Contrary to expectations, we found that merely expanding the training dataset did not guarantee improved outcomes. Instead, the variance in image content, considering distances, angles, and turtle appearances, played a pivotal role in enhancing model precision. Through our experimentation, the streamlined YOLOv5s model consistently eclipsed its more complex counterparts in performance. An AI service, underpinned by the YOLOv5s model, has been launched to distinguish between green sea turtle types for tourist-focused conservation initiatives. Future iterations will incorporate user feedback to refine accuracy. Our research breaks new ground, spotlighting the intricacies of gathering natural environment data, pinpointing optimal AI models, and evaluating their practical implications for green sea turtle conservation.