Marine Ecosystems Research Articles

Continuous warming drives the colonization dynamics of periphytic ciliate fauna in marine environments.

In order to evaluate the influence of global warming on the ecosystem processes in marine environments, the changes in colonization dynamics of periphytic microbiota were studied using the periphytic ciliate communities as the test organism fauna under a continuous warming gradient of 22℃ (control), 25℃, 28℃, 31℃, and 34 ℃. The results demonstrated that (1) the test ciliate communities generally showed a similar temporal pattern in within the colonization process under the water temperatures from 22 up to 28℃; however, (2) the colonization dynamics were significantly changed, and the fitness of colonization curves to the MacArthur-Wilson model equation was failed under the temperature increased by 6 ℃, and (3) the loading or assimilative capacity of the test aquatic ecosystem was decreased with the increase of water temperature. Therefore, this study suggests that continuous warming may significantly drive the colonization dynamics of periphytic ciliates in marine ecosystems.

Evaluating the influence of marine protected areas on surf zone fish.

Marine protected areas (MPAs) globally serve conservation and fisheries management goals, generating positive effects in some marine ecosystems. Surf zones and sandy beaches, critical ecotones bridging land and sea, play a pivotal role in the life cycles of numerous fish species and serve as prime areas for subsistence and recreational fishing. Despite their significance, these areas remain understudied when evaluating the effects of MPAs. We compared surf zone fish assemblages inside and outside MPAs across 3 bioregions in California (USA). Using seines and baited remote underwater videos (BRUVs), we found differences in surf zone fish inside and outside MPAs in one region. Inside south region MPAs, we observed higher abundance (Tukey's honest significant difference [HSD]=0.83, p=0.0001) and richness (HSD=0.22, p=0.0001) in BRUVs and greater biomass (HSD=0.32, p=0.0002) in seine surveys compared with reference sites. Selected live-bearing, fished taxa were positively affected by MPAs. Elasmobranchs displayed greater abundance in BRUV surveys and higher biomass in seine surveys inside south region MPAs (HSD=0.35, p=0.0003 and HSD=0.23, p=0.008, respectively). Although we observed no overall MPA signal for Embiotocidae, abundances of juvenile and large adult barred surfperch (Amphistichus argenteus), the most abundant fished species, were higher inside MPAs (K-S test D=0.19, p<0.0001). Influence of habitat characteristics on MPA performance indicated surf zone width was positively associated with fish abundance and biomass but negatively associated with richness. The south region had the largest positive effect size on all MPA performance metrics. Our findings underscored the variability in species richness and composition across regions and survey methods that significantly affected differences observed inside and outside MPAs. A comprehensive assessment of MPA performance should consider specific taxa, their distribution, and the effects of habitat factors and geography.

Group 2i Isochrysidales thrive in marine and lacustrine systems with ice cover

Global warming is causing rapid changes to the cryosphere. Predicting the future trajectory of the cryosphere requires quantitative reconstruction of its past variations. A recently identified sea-ice-associated haptophyte, known as Group 2i Isochrysidales, has given rise to a new sea-ice proxy with its characteristic alkenone distributions. However, apart from the occurrence of Group 2i Isochrysidales in regions with sea ice, and the empirical relationship between C37:4 alkenone abundance and sea-ice concentration, little is known about the ecology of these haptophyte species. Here, we systematically mapped the spatial and temporal occurrence of known Group 2i Isochrysidales based on environmental DNA in both marine and lacustrine environments. Our results indicate Group 2i is widely distributed in icy marine and lacustrine environments in both Northern and Southern Hemisphere, but is absent in warm environments. Temporally, Group 2i is part of the sea-ice algae bloom during the cold seasons, in contrast to other Isochrysidales that bloom in open waters during warm seasons. Our results indicate that ice is a prerequisite for the occurrence of the psychrophilic Group 2i haptophytes in marine and lacustrine ecosystems and further affirms its value for past ice reconstructions.

The complementary relationship between illegal fishing and maritime piracy: A case study of the Gulf of Guinea

This research paper investigates the interrelationship between maritime crime, specifically sea piracy, and illegal fishing. Existing studies primarily focus on the link between piracy and illegal fishing activities carried out by foreign trawlers, drawing evidence from Somali piracy cases. A causal narrative in past works highlights the detrimental effects of foreign trawlers on local marine resources, ecosystems, and livelihoods, thereby driving local fishers to turn toward piracy and prompting coastal states to address the key issue of illegal fishing by foreign vessels.However, this emphasis on external perpetrators can lead states to pay less attention to local actors involved in illegal fishing and maritime piracy. Therefore, this study redirects our attention to local perpetrators who engage in illegal fishing and maritime piracy. It explores the complementary relationship between these two types of crimes. Our findings indicate that reducing illegal fishing activities in a local area enhances the likelihood of maritime piracy occurrence. By shedding light on the complementarity between illegal fishing and maritime piracy, this research provides valuable insights for policymakers and law enforcement agencies involved in combating maritime crime. It underscores the importance of locally addressing illegal fishing and piracy using a more holistic approach.

Temperature-driven dynamics: unraveling the impact of climate change on cryptic species interactions within the Litoditis marina complex

Anthropogenic climate change and the associated increase in sea temperatures are projected to greatly impact marine ecosystems. Temperature variation can influence the interactions between species, leading to cascading effects on the abundance, diversity and composition of communities. Such changes in community structure can have consequences on ecosystem stability, processes and the services it provides. Therefore, it is important to better understand the role of species interactions in the development of communities and how they are influenced by environmental factors like temperature. The coexistence of closely related cryptic species, with significant biological and ecological differences, makes this even more complex. This study investigated the effect of temperature on species growth and both intra- and interspecific interactions of three species within the free-living nematode Litoditis marina complex. To achieve this, closed microcosm experiments were conducted on the L. marina species Pm I, Pm III and Pm IV in monoculture and combined cultures at two temperature treatments of 15 °C and 20 °C. A population model was constructed to elucidate and quantify the effects of intra- and interspecific interactions on nematode populations. The relative competitive abilities of the investigated species were quantified using the Modern Coexistence Theory (MCT) framework. Temperature had strong and disparate effects on the population growth of the distinct L. marina species. This indicates temperature could play an important role in the distribution of these cryptic species. Both competitive and facilitative interactions were observed in the experiments. Temperature affected both the type and the strength of the species interactions, suggesting a change in temperature could impact the coexistence of these closely related species, alter community dynamics and consequently affect ecosystem processes and services.

Jellyfish in Hong Kong: a citizen science dataset

The Hong Kong Jellyfish Project is a citizen science initiative started in early 2021 to enhance our understanding of jellyfish in Hong Kong. Here, we present a dataset of jellyfish sightings collected by citizen scientists from 2021 through 2023 within local waters. Citizen scientists submitted photographs and other data (time, date, and location) using a website, iNaturalist project, and social media. Sightings were validated using references from the literature. A total of 1,020 usable observations are included in this dataset, showing the occurrence and distribution of jellyfish in Hong Kong in 2021–2023. This dataset is now publicly available and discoverable in the Global Biodiversity Information Facility database and is available for download. This data can be used to enhance our understanding of the biodiversity of local marine ecosystems.

Ultraviolet Filters: Dissecting Current Facts and Myths

Skin cancer is a global and increasingly prevalent issue, causing significant individual and economic damage. UV filters in sunscreens play a major role in mitigating the risks that solar ultraviolet radiation poses to the human organism. While empirically effective, multiple adverse effects of these compounds are discussed in the media and in scientific research. UV filters are blamed for the disruption of endocrine processes and vitamin D synthesis, damaging effects on the environment, inducement of acne and neurotoxic and carcinogenic effects. Some of these allegations are based on scientific facts while others are simply arbitrary. This is especially dangerous considering the risks of exposing unprotected skin to the sun. In summary, UV filters approved by the respective governing bodies are safe for human use and their proven skin cancer-preventing properties make them indispensable for sensible sun protection habits. Nonetheless, compounds like octocrylene and benzophenone-3 that are linked to the harming of marine ecosystems could be omitted from skincare regimens in favor of the myriad of non-toxic UV filters.

Development of a New Aggregation Method to Remove Nanoplastics from the Ocean: Proof of Concept Using Mussel Exposure Tests

The overproduction and mismanagement of plastics has led to the accumulation of these materials in the environment, particularly in the marine ecosystem. Once in the environment, plastics break down and can acquire microscopic or even nanoscopic sizes. Given their sizes, microplastics (MPs) and nanoplastics (NPs) are hard to detect and remove from the aquatic environment, eventually interacting with marine organisms. This research mainly aimed to achieve the aggregation of micro- and nanoplastics (MNPs) to ease their removal from the marine environment. To this end, the size and stability of polystyrene (PS) MNPs were measured in synthetic seawater with the different components of the technology (ionic liquid and chitosan). The MPs were purchased in their plain form, while the NPs displayed amines on their surface (PS NP-NH2). The results showed that this technology promoted a significant aggregation of the PS NP-NH2, whereas, for the PS MPs, no conclusive results were found, indicating that the surface charge plays an essential role in the MNP aggregation process. Moreover, to investigate the toxicological potential of MNPs, a mussel species (M. galloprovincialis) was exposed to different concentrations of MPs and NPs, separately, with and without the technology. In this context, mussels were sampled after 7, 14, and 21 days of exposure, and the gills and digestive glands were collected for analysis of oxidative stress biomarkers and histological observations. In general, the results indicate that MNPs trigger the production of reactive oxygen species (ROS) in mussels and induce oxidative stress, making gills the most affected organ. Yet, when the technology was applied in moderate concentrations, NPs showed adverse effects in mussels. The histological analysis showed no evidence of MNPs in the gill’s tissues.

Seasonal Prevalence of Skin Lesions on Dolphins across a Natural Salinity Gradient

Bottlenose dolphins (Tursiops truncatus) inhabit waters across a broad natural salinity gradient and exhibit changes in skin condition based on the quality of their environment. Prolonged exposure to low salinities (≤10–20 ppt) degenerates the epidermal barrier and causes cutaneous lesions in dolphins, while the role of high salinity exposure (&gt;35 ppt) in lesion development remains unknown. We assessed seasonal lesion prevalence in three free-ranging dolphin stocks inhabiting coastal Gulf of Mexico (GoM) waters of different salinities (0–30 ppt, 22–35 ppt, and 36+ ppt) using images of dolphin bodies. Lesions were documented on 44% of the dolphins photographed (n = 432), and lesion occurrence was significantly related to cold seasons and water temperatures but not salinity. Cold water temperatures may heighten dolphin susceptibility to infectious pathogens and disease and compound the effects of anthropogenic pollutants in the GoM. As dolphins are a bioindicator species of marine habitat welfare, natural studies assessing dolphin skin may reveal environmental degradation with potential impacts on marine ecosystems and human health.

Diversity and biogeography of dinoflagellates in the Kuroshio region revealed by 18S rRNA metabarcoding

Dinoflagellate is one of the most diverse and pervasive protists and a fundamental player in the marine food web dynamics and biogeochemical cycles. While possessing different nutritional strategies from purely autotrophy or heterotrophy to mixotrophy, some of them are also known as toxic harmful algal bloom (HAB) formers over the world. Despite their ordinariness, their diversity and biogeography are understudied in the open ocean compared with coastal region. As the first metabarcoding survey covering the Kuroshio current region from the offshore of Okinawa to the south of Honshu, we investigated the distribution of free-living dinoflagellates using the hypervariable V4 and V9 regions on 18S rRNA and their relation to ambient environments influenced by this oligotrophic but highly productive current in the northwest Pacific Ocean. We observed community structures differentiated by depth and nutrient concentrations. Most species annotated are autotrophic or mixotrophic and had a distribution correlated to warmer surface water, whereas heterotrophic species correlated to high nutrient levels or deeper layer. Our results also confirmed the overall high genetic diversity of dinoflagellates that decreased with depth and onshore. Most species present at stations offshore, and the relative abundance of HAB assemblages was lower at nutrient-rich stations on the continental shelf than stations influenced by the Kuroshio current, exhibiting the role of the Kuroshio transporting dinoflagellates including HAB species. To fully understand the dynamics of dinoflagellate communities in marine ecosystems, further seasonal monitoring is foremost for correlating dinoflagellates and environmental factors while completing the reference genomic database.

Microscopic Image Dataset with Segmentation and Detection Labels for Microplastic Analysis in Sewage: Enhancing Research and Environmental Monitoring

We introduce a novel microscopic image dataset augmented with segmentation and detection labels specifically designed for microplastic analysis in sewage environments. Recognizing the increasing concern over microplastics—particles of synthetic polymers smaller than 5 mm—and their detrimental effects on marine ecosystems and human health, our research focuses on enhancing detection and analytical methodologies through advanced computer vision and deep learning techniques. The dataset comprises high-resolution microscopic images of microplastics collected from sewage, meticulously labeled for both segmentation and detection tasks, aiming to facilitate accurate and efficient identification and quantification of microplastic pollution. In addition to dataset development, we present example deep learning models optimized for segmentation and detection of microplastics within complex sewage samples. The models demonstrate significant potential in automating the analysis of microplastic contamination, offering a scalable solution to environmental monitoring challenges. Furthermore, we ensure the accessibility and reproducibility 12 of our research by making the dataset and model codes publicly available, accompanied by detailed 13 documentation on GitHub and LabelBox.

Sustainable Enzymatic Production of Omega-3 Oil from Squid Viscera

Fish oils are widely consumed around the world to increase omega-3 fatty acid intake. Due to negative impacts on marine resources and ecosystems from an increasing demand for fish, alternative sustainable sources are under investigation. Squid viscera contains up to 10% oil by mass and is available as a byproduct from squid processing. Squid viscera oil is a source of EPA and DHA and contains the xanthophyll carotenoid astaxanthin, known for its significant anticancer, antioxidant, antidiabetic, and cardiovascular properties. In the raw form, squid viscera oil has a high free fatty acid (FFA) content, so conventional alkaline refining results in low yield and loss of astaxanthin. As a higher-yielding alternative, the current study optimized lipase-catalyzed glycerolysis of squid viscera oil to convert FFA into acylglycerol using a custom-built one-liter immobilized enzyme reactor. To monitor the reaction progress and assess its impact on the oil, we analyzed lipid classes, fatty acid composition and astaxanthin levels. Under optimized conditions, FFA was reduced from 40% to 2.7% in 10 h and 1.7% in 24 h, with no significant effect on EPA and DHA levels, and astaxanthin being retained. Squid viscera presents a safe and sustainable additional source of marine-derived EPA and DHA oil.

Microplastic Contamination of the Seawater in the Hamsilos Bay of the Southern Black Sea

The marine ecosystem is severely threatened by microplastics. The entire marine environment of the Black Sea is contaminated with both macro- and microplastics but the contamination of the water column with this pollutant has received less attention. This study aims to obtain data on the microplastic abundance, and vertical and temporal distribution of the microplastics in the water column of Hamsilos Bay which is a natural protected area, and an important area for fishery and tourism on the Sinop coast in the Black Sea. This study was carried out for 12 months in 7 stations. Microplastic abundance varied among 5.58 ± 6.12–8.12 ± 9.17 pieces/m3 in and 1.74 ± 0.80–21.07 ± 3.84 pieces/m3 in stations. The dominant microplastics were fibre by shape (73.92%), 1–2 mm (28.35%) by size class, and blue (37.98%) by colour. The synthetic polymers in the examined microplastic samples of this study were PET (47%), PE (34%), HDPE (10%), PVC (7%) and PS (2%). The results of this study show that the coastal area is widely contaminated with microplastics. Microplastic pollution is an increasingly significant environmental issue that poses a threat to the Black Sea which is particularly vulnerable to microplastic pollution. The region is an important ecological hotspot in the Black Sea and this study can provide valuable insights into the extent of microplastic pollution and will contribute to the literature on the evaluation of microplastic pollution in marine ecosystems. These types of investigations; efforts to address the environmental challenges facing the Black Sea, including the development of programs to reduce pollution, increase sustainability, and support the protection of the region's natural resources, are crucial to its continuity.

Tech-Business Analytics in Blue Economy

Purpose: Utilising cutting-edge technologies, data analytics, and entrepreneurial strategies to promote innovation, develop resilience, and drive sustainable growth are the main goals of Tech-Business projects in the Blue Economy for industries associated to the marine sector. Design/Methodology/Approach: A methodical approach that combines cutting-edge technologies, analytical techniques, and commercial strategies is used to implement Tech-commercial initiatives in the Blue Economy. Findings/Result: The results highlight the revolutionary effect of Tech-Business endeavours in propelling eco-friendly expansion, stimulating creativity, and fortifying the Blue Economy. Stakeholders can open up new possibilities and build a more affluent and sustainable future for coastal communities and marine ecosystems by embracing data-driven initiatives and utilising technology. Originality/Value: The uniqueness of Tech-Business endeavours in the Blue Economy is found in their creative methods of resolving persistent issues and opening up fresh doors in the maritime sector. Paper Type: Exploratory Research on Technology Management.

From molecules to morphology: How food supply influences the larvae of sea urchins across all levels of biological organization.

An important goal of many studies in molecular ecology is to utilize molecular tools to elucidate how critical traits like metabolism and growth are affected by environmental stressors and how organisms offset these stresses by adaptive molecular-level responses. Stress from food deprivation may be critical for early developmental stages that require a continued supply of substrates for energy metabolism and growth if development is to be completed. In a 'From the Cover' article in this issue of Molecular Ecology, Li etal.(2023) examined the effects of withholding food (unicellular algae) on 10 traits of larvae of the purple sea urchin (Strongylocentrotus purpuratus), ranging from the molecular level (gene expression) to morphology. Overall, this study sheds new light on the plasticity of larval development and the tight linkages that exist among traits as they respond to changes in food availability. Importantly, shifts in the sources of food utilized under different dietary treatments show the plasticity of these larvae to alter reliance on endogenous energy stores and dissolved organic matter (DOM) as algae deprivation continues. The effects of global change on the amounts and phenology of productivity in the seas make this type of integrated, multi-level analysis an important tool for predicting the future states of marine ecosystems.

Microbial Detoxification of Sediments Underpins Persistence of Zostera marina Meadows

Microbial Detoxification of Sediments Underpins Persistence of Zostera marina Meadows

Deploying a Computer Vision Model Based on YOLOv8 Suitable for Drones in the Tuna Fishing and Aquaculture Industry

In recent years, the global tuna fishing and aquaculture industry has encountered significant challenges in balancing operational efficiency with sustainable resource management. This study introduces an innovative approach utilizing an advanced computer vision model, PA-YOLOv8, specifically adapted for drones, to enhance the monitoring and management of tuna populations. PA-YOLOv8 leverages the capabilities of YOLOv8, a state-of-the-art object detection system known for its precision and speed, tailored to address the unique demands of aerial surveillance in marine environments. Through comprehensive modifications including downsampling techniques, feature fusion enhancements, and the integration of the Global Attention Module (GAM), the model significantly improves the detection accuracy of small and juvenile tuna within complex aquatic landscapes. Experimental results using the Tuna dataset from Roboflow demonstrate marked improvements in detection metrics such as precision, recall, and mean average precision (mAP), affirming the model’s effectiveness. This study underscores the potential of integrating cutting-edge technologies like UAVs and computer vision in promoting sustainable practices in the aquaculture sector, setting a new standard for technological applications in environmental and resource management. The advancements presented here provide a scalable and efficient solution for real-time monitoring, contributing to the long-term sustainability of marine ecosystems.

Environmental impacts from large-scale offshore renewable-energy deployment

Abstract The urgency to mitigate the effects of climate change necessitates an unprecedented global deployment of offshore renewable-energy technologies &amp;#xD;mainly including offshore wind, tidal stream, wave energy, and floating solar photovoltaic. To achieve the global energy demand for terawatt-hours, the infrastructure for such technologies will require a large spatial footprint. Accommodating this footprint will require rapid landscape evolution, ideally within two decades. For instance, the United Kingdom has committed to deploying 50 GW of offshore wind by 2030 with 90--110 GW by 2050, which is equivalent to four times and ten times more than the 2022 capacity, respectively. If all were 15-MW turbines spaced 1.5 km apart, 50 GW would require 7,500 km2 and 110 GW would require 16,500 km2. This review paper aims to anticipate environmental impacts stemming from the large-scale deployment of offshore renewable energy. These impacts have been categorised into three broad types based on the region (i.e., atmospheric, hydrodynamic, ecological). We synthesise our results into a table classifying whether the impacts are positive, negative, negligible, or unknown; whether the impact is instantaneous or lagged over time; and whether the impacts occur when the offshore infrastructure is being constructed, operating or during decommissioning. Our table benefits those studying the marine ecosystem before any project is installed to help assess the baseline characteristics to be considered in order to identify and then quantify possible future impacts.

Timing and pattern of the Devonian Nehden event: Implication for the biotic recovery following the F–F extinction event

The biotic recovery process following the Frasnian–Famennian (F–F) mass extinction played an important role in reestablishing the late Palaeozoic marine ecosystem. The Nehden event is assumed as the global biotic recovery process in the aftermath of the F–F mass extinction, but the timing and pattern of this event is still in dispute due to lack of consistent geological records. In order to recognize the Nehden event and elucidate its timing and pattern, a newly refined conodont biostratigraphic framework spanning the Palmatolepis minuta minuta Zone to the Pa. rhomboidea Zone (370.8–367 Ma) has been established in the Yangdi section, Guangxi, South China. Based on a detailed analysis of microfacies and carbon isotope of carbonates (δ13Ccarb), the start of the Nehden event has been placed at the upper part of the Pa. m. minuta Zone, marked by deposition of calcareous shales and proliferation of palmatolepid conodonts and ostracods. Two episodes of the Nehden event are recognized in this study according to integrated palaeontological, sedimentological, and geochemical data from South China and other continents. The first phase of the Nehden event is assigned at the upper part of the Pa. m. minuta Zone, characterized by radiation of conodonts, ostracods, and brachiopods, which is coincident with the minimum value of negative δ13Ccarb excursion and climate warming. The second phase is placed at the Pa. termini to Pa. glabra pectinata zones, documented by biodiversification of cheiloceratid ammonoids and phacopid trilobites, which is concurrent with climate warming and the maximum transgression during the early Famennian. The extensive development of microbial bindstone in the lower Famennian succession at Yangdi demonstrates that microbial communities occupied the vacant ecological niches left behind by metazoans after the F–F biotic crisis. The expansion of ecological niches of microbial communities and depauperation of metazoan reefs implies the bioconstructor turnover from metazoan to microbial communities following the F–F extinction. The time equivalence of biotic radiation, climate change and sea-level fluctuation in two episodes of the Nehden event indicates the early Famennian biotic recovery was favored by climate warming and transgression. The results in this study not only offer important data to constrain the timing of the Nehden event, but also provide an insight on the process of biotic recovery following the F–F mass extinction event.

Regional comparison of the structure of human well-being related to ecosystem services in coastal areas of Japan: possible effect of anxiety unique to the ria coast

AbstractPeople living in coastal areas have the advantage of accessing a high level of ecosystem services, but are also exposed to the dangers inherent in living by the sea in an area prone to natural disasters. To achieve sustainable utilization of the high ecosystem services of coastal areas, establishment of an effective marine policy based on regional characteristics of human–nature interactions is essential. We compared the structure of perceived satisfaction for five components of human well-being (‘Security’, ‘Basic material for a good life’, ‘Good social relations’, ‘Health’, and ‘Freedom of choice and action’) derived from coastal ecosystem services among three sites in Japan (Wakasa, Sanriku, and Shima) that share the same natural and social backgrounds: highly dependent on fisheries industry, located in the same climate regime (temperate zone), and have similar topographical features (ria coast). Structural equation modeling using the results from questionnaire surveys showed that the three sites shared a common basic structure of the interactions among the five components of human well-being. However, the intensity of interactions among components differed among the three sites. Questionnaire surveys on anxiety about natural disasters and future access to marine ecosystem services were simultaneously conducted at the three sites. The site-specific anxieties were responsible for the difference in the interactions among the five components of human well-being. We propose a method that quantitatively evaluates both positive (satisfaction) and negative (anxiety) aspects of respondents’ subjective assessment as a useful tool for understanding the diversity of human–nature interactions caused by the region-specific natural and social backgrounds of coastal areas.