Coastal Marine Ecosystems Research Articles

Influence of marine habitat on microplastic prevalence in forage fish and salmon in the Salish Sea

Microplastics are increasingly prevalent in marine systems and are a growing concern as a marine pollutant and contaminant with consequences for high trophic level consumers, including humans. Given evidence that links plastics to degraded ecosystem functioning and organismal health, there is increased interest in understanding the prevalence, fate and consequences of marine plastics. Microplastics contain and absorb harmful chemicals which may serve as endocrine disruptors and have negative implications for growth, reproductive health, and longevity. To expand current knowledge on microplastics in coastal marine ecosystems and the potential for biomagnification in marine food webs, we conducted stomach analyses of microplastics in Pacific salmon (Oncorhynchus spp.) and Pacific sand lance (Ammodytes personatus), an important prey for salmon. Prevalence of microplastics was substantial; 77 % of all salmon and 25 % of all sand lance stomachs contained at least one microplastic. Fish were sampled at multiple sites throughout the inland Salish Sea, including beaches and sediment bedforms for Pacific sand lance and open-water pelagic habitat for Pacific salmon. Pacific sand lance sampled at beach sites had more microplastics compared to those sampled in subtidal sediments and there were more plastics in sand lance at a protected beach site as compared to an exposed beach site. Prevalence of plastics in salmon differed according to species and included analyses of pink salmon (Oncorhynchus gorbuscha), Chinook (Oncorhynchus tshawytscha), and Coho salmon (Oncorhynchus kisutch); plastics were predominantly fibers in all species, though there were relatively higher rates of ingestion of films and particles in Chinook. Comparisons between plastic concentrations and stomach fullness indicated a slight negative trend, suggesting that plastics may be retained. Further investigation is needed to develop a more thorough understanding of the prevalence and fate of microplastics in coastal marine systems such as the Salish Sea, their concentration within marine food webs, and the implications for species targeted in fisheries.

Temporal change in phytoplankton diversity and functional group composition

One of the key challenges in managing eutrophication in coastal marine ecosystems is the harmonized cross-border assessment of phytoplankton. Some general understanding of the consequences of shifting nutrient regimes can be derived from the detailed investigation of the phytoplankton community and its biodiversity. Here, we combined long-term monitoring datasets of German and Dutch coastal stations and amended these with additional information on species biomass. Across the integrated and harmonized dataset, we used multiple biodiversity descriptors to analyse temporal trends in the Wadden Sea phytoplankton. Biodiversity, measured as the number of species (S) and the effective number of species (ENS), has decreased in the Dutch stations over the last 20 years, while biomass has increased, indicating that fewer species are becoming more dominant in the system. However, biodiversity and biomass did not show substantial changes in the German stations. Although there were some differences in trends between countries, shifts in community composition and relative abundance were consistent across stations and time. We emphasise the importance of continuous and harmonized monitoring programmes and multi-metric approaches that can detect changes in the communities that are indicative of changes in the environment.

Intercomparison of marine tracer and catchment-based submarine groundwater discharge estimates for a karst aquifer

Submarine groundwater discharge (SGD) is a major source of solutes to the ocean. Consequently, the accuracy of estimates of the magnitude and seasonal variability of SGD is critical for the management of coastal marine ecosystems. However, very few intercomparison studies between different conceptual approaches have been made to assess the reliability and consistency of SGD flow estimates while simultaneously gauging the applicability of underlying models and budget assumptions in real-world scenarios. To date, intercomparison efforts have focused on homogeneous aquifers, and less so on highly heterogeneous aquifers such as karst systems. Here we compare the results of tracer-based (salt mass balance, tidal prism and radon mass balances) and catchment-based methods (water balance, semi-distributed karst network model) to assess SGD at a data-rich coastal location. All approaches tested here reveal a positive relationship between SGD fluxes and groundwater level measured close to the preferential groundwater flow pathways in the phreatic karst aquifer (e.g. water-saturated conduits or fracture network). We use this finding to derive site-specific relationships between groundwater level and SGD flow rates. We derive these relationships from least square fitting of Darcian and Non-Darcian models and regression analysis. The relationships validate the findings derived independently from hydraulic/hydrogeological modelling of the complex karst networks. By combining various estimates made with distinct assumptions, this method produces robust estimates of the SGD seasonal variability, essential to develop optimal management strategies of SGD resources in coastal karstic regions. Where direct measurements of SGD are not possible, monitoring of coastal groundwater level close to preferential phreatic groundwater pathways can be thus used as a useful indicator to compare past groundwater flow measurements and derive site-specific relationships, particularly in settings where large flow rate changes are present such as karst aquifers.

The NOAA NCEI marine microplastics database

Microplastics (<5 mm) pollution is a growing problem affecting coastal communities, marine ecosystems, aquatic life, and human health. The widespread occurrence of marine microplastics, and the need to curb its threats, require expansive, and continuous monitoring. While microplastic research has increased in recent years and generated significant volumes of data, there is a lack of a robust, open access, and long-term aggregation of this data. The National Oceanic and Atmospheric Administration (NOAA) National Centers for Environmental Information (NCEI) now provides a global open access to marine microplastics data on an easily discoverable and accessible GIS web map and data portal (https://www.ncei.noaa.gov/products/microplastics). The objective of this data portal is to develop a repository where microplastics data are aggregated, archived, and served in a user friendly, consistent, and reliable manner. This work contributes to NCEI’s efforts towards data standardization, integration, harmonization, and interoperability among national and international collaborators for monitoring global marine microplastics. This paper describes the NOAA NCEI global marine microplastics database, its creation, quality control procedures, and future directions.

Early Warning of Red Tide of Phaeocystis globosa Based on Phycocyanin Concentration Retrieval in Qinzhou Bay, China

Phaeocystis globose (P. glo) are the most frequent harmful algae responsible for red tides in Qinzhou Bay, Guangxi. They pose a significant threat to the coastal marine ecosystem, making it essential to develop an efficient indicator method tailored to P. glo outbreaks. In remote sensing water quality monitoring, there is a strong correlation between P. glo and cyanobacteria, with phycocyanin (PC) serving as an indicator of cyanobacterial biomass. Consequently, existing research has predominantly focused on remote sensing monitoring of medium to high PC concentrations. However, it is still challenging to monitor low PC concentrations. This paper introduced the BP neural network (BPNN) and particle swarm optimization algorithm (PSO). It selects spectral bands and indices sensitive to PC concentrations and constructs a PC concentration retrieval model, in combination with meteorological factors, offering a comprehensive exploration of the indicative role of low PC concentrations in predicting P. glo red tide outbreaks in Qinzhou Bay. The results demonstrated that the PC concentration retrieval model, based on the backpropagation neural network optimized by the particle swarm optimization algorithm (PSO-BPNN), demonstrated better performance (MAE = 0.469, RMSE = 0.615). In Qinzhou Bay, PC concentrations were mainly concentrated around 2~5 μg/L. During the P. glo red tide event, the area with undetectable PC concentrations (PC &lt; 0.04 μg/L) increased by 4.97 km2, with regions below 0.9 μg/L experiencing exponential growth. Considering the variations in PC concentrations along with meteorological factors, we proposed a straightforward early warning threshold for P. glo red tides: PC &lt; 0.9 μg/L and T &lt; 20 °C. This method, from a remote sensing perspective, analyzes the process of P. glo outbreaks, simplifies PC concentration monitoring, and provides a reasonably accurate prediction of the risk of P. glo red tide disasters.

Population genomics of an Octopus species identify oceanographic barriers and inbreeding patterns

Coastal marine ecosystems are highly productive and important for global fisheries. To mitigate over exploitation and to establish efficient conservation management plans for species of economic interest, it is necessary to identify the oceanographic barriers that condition divergence and gene flow between populations with those species, and that determine their relative amounts of genetic variability. Here, we present the first population genomic study of an Octopus species, Octopus insularis, which was described in 2008 and is distributed in coastal and oceanic island habitats in the tropical Atlantic Ocean. Using genomic data, we identify the South Equatorial current as the main barrier to gene flow between southern and northern parts of the range, followed by discontinuities in the habitat associated with depth. We find that genetic diversity of insular populations significantly decreases after colonization from the continental shelf, also reflecting low habitat availability. Using demographic modelling, we find signatures of a stronger population expansion for coastal relative to insular populations, consistent with estimated increases in habitat availability since the Last Glacial Maximum. The direction of gene flow is coincident with unidirectional currents and bidirectional eddies between otherwise isolated populations. Together, our results show that oceanic currents and habitat breaks are determinant in the diversification of coastal marine species where adults have a sedentary behavior but paralarvae are dispersed passively, shaping standing genetic variability within populations. Lower genetic diversity within insular populations implies that these are particularly vulnerable to current human exploitation and selective pressures, calling for the revision of their protection status.

What do small cetaceans tell us about trace elements pollution on the Argentinean coast? Franciscana dolphin as a biomonitor

Trace elements (TEs) constitute the oldest emerging pollutants globally, most occur from natural sources, but a few are derived from anthropogenic sources. Marine mammals are considered bioindicators of ecosystem contamination. The aims of this review is compile reports on essential and nonessential TEs occurrence in small cetaceans from Argentinean waters; and to review the existing information on the concentration of TEs in the Franciscana dolphin, a biomonitor species of the Argentine coastal marine ecosystem. We searched reports where levels of TEs were present in small cetaceans from and eight species were analysed: Pontoporia blainvillei, Tursiops truncatus gephyreus, Kogia breviceps, Delphinus delphis, Lagenorhynchus obscurus, Lagenodelphis hasei, Cephaloryhchus commersonii and Ziphius cavirostris. Essential TEs like Zn, Cu, Mn, Cr, Fe, Co, Ni, Mo, Se, As, Au, Ag, Sn, and nonessential TE as Pb, Cd, Hg, As was considered. The reports compiled in this article analysed kidney, liver, muscle and occasionally brain, skin, lung and spleen, covering a temporal range of 30 years, from 1982 to 2016. Of data analysis, we identify knowledge gaps, species of small cetaceans for which the concentration of trace metals is not yet known and areas on the Argentine coast where there are no reports that analyse them. The most recent information corresponds to the 2010 decade, and in those subsequent publications, the samples were taken at that time. This emphasizes the importance of reviewing this data, in order to compare old and new datasets, create contamination timelines and evaluate possible increases or decreases of contaminants in different study areas. The information recopilated will serve as valuable baselines to detect the future impact of increasing human, even natural, activities on marine ecosystems in the South Atlantic Ocean.

Identification of seagrass beds using high-resolution satellite imagery to basic inventory data supporting coastal ecosystem management (Case study: Lancang Island)

Seagrass habitat is an important element of the coastal marine ecosystem, as it influences all major fields in the coastal environments. Due to anthropogenic and natural pressure, such identification of habitat distribution becomes crucial. Remote sensing can provide the best solution regarding time and cost to extract seagrass beds’ spatial and temporal information. When the low spatial resolution satellite image provides low accuracy and high uncertainty of seagrass distribution, we assess the high spatial resolution image product, the WorldView-2 image, to identify the seagrass bed distribution in Lancang Island. We confidently found that higher resolution images could leverage the mapping quality, especially on the seagrass beds, which could be highly sensitive to miss-detection. We can produce 83,75% overall accuracy using pixel-based classification; this is better among other low-resolution images for Instants, Landsat, and Sentinel. Our results suggest that the WorldView-2 image could perform better on seagrass beds identification, yet further improvement on more robust classification methods and algorithms could amplify the mapping and monitoring strategy. Based on this, it can be used as basic data to support future coastal ecosystem management on Lancang Island.

A Preliminary Assessment of Microalgal Diets for Echinopluteus Larvae Culture of the Sea Urchin Sphaerechinus granularis (Lamarck, 1816) (Echinoidea: Toxopneustidae)

Sea urchins play an important role in coastal marine ecosystems and are an economically valuable resource for their gonads (roe or uni). Increased demand by Asian and European countries caused overfishing of wild stocks resulting in a sharp decline of sea urchin populations. The increased efforts in developing cost-effective protocols are focused on larval development up to pre- and post-metamorphosis stages, as they are one of the main difficulties of echinoculture. This is a preliminary study to evaluate the influence of microalgal varying diet rationing on larval development, growth, and survivorship at pre-metamorphosis of Sphaerechinus granularis echinopluteus (30 days post-fertilization). Three microalgae diets based on Dunaliella tertiolecta and Rhodomonas marina and the combination of both species were tested. Each diet used three ration treatments: low ration (500–3000 cells⋅ml−1); medium ration (1000–6000 cells⋅ml−1); and high ration (4000–24,000 cells⋅ml−1), which were cell-density adjusted to larval development. Assays used three triplicated treatments in 8 L cylindrical–conical glass incubators. Results showed that the survival of S. granularis echinopluteus was positively influenced by diets of lower cellular densities and a combined microalgae diet. Adoption of this type of diet regime is expected to improve larval production and provide the groundwork for future research on S. granularis in aquaculture.

Do DOM quality and origin affect the uptake and accumulation of lipid-soluble contaminants in coastal filter feeders? An experimental simulation of teflubenzuron exposure to blue mussels

The increased export of terrestrial dissolved organic matter (terrDOM) to coastal marine ecosystems may affect local filter feeders and the local food web via the altered uptake of organic material and associated contaminants. To compare terrDOM to marine DOM (marDOM) as contaminant vectors to coastal biota, we exposed blue mussels (Mytilus sp.) to the different DOM types in combination with teflubenzuron, a widely applied lipophilic aquaculture medicine targeting salmon lice (Lepeophtheirus salmonis). A 16-day exposure of the blue mussels to DOM and teflubenzuron was followed by a depuration phase of 20 days without teflubenzuron. We calculated teflubenzuron adsorption rates and bioaccumulation factors (BAF) using a Bayesian model, expecting teflubenzuron uptake to be greater with terrDOM than marDOM due to the higher prevalence of large amphipathic humic acids in terrDOM. Humic acids have strong absorption properties and are able to envelope lipophilic molecules. Thus, humic acids can function as an efficient contaminant vector when taken up by filter feeders. Although there were varying degrees of overlap, the mussels tended to accumulate higher amounts of teflubenzuron in the DOM treatments than in the seawater control (bioaccumulation factor [BAF] in seawater: median 106 L/kg; 2.5 %–97.5 % percentile: 69–160 L/kg). Contrary to expectations, mussels exposed to marDOM showed a trend toward more bioaccumulation of teflubenzuron than those exposed to terrDOM (BAF marine 144 L/kg; 102–221 L/kg versus BAF terrestrial: 121 L/kg; 82–186 L/kg). The highest teflubenzuron accumulation was observed with the 50:50 mixture of marDOM and terrDOM (BAF mix: 165 L/kg; 117–244 L/kg). The slight difference in DOM-type accumulation rates observed in this experiment—especially the accumulation rate of terrDOM compared to that of the seawater-only treatment type—was not considered environmentally relevant. Further studies are necessary to see if the observed trends transfer to complex environmental systems.

Spatiotemporal response of water quality in fragmented mangroves to anthropogenic activities and recommendations for restoration

Mangroves have received substantial attention for their pivotal role as ecological barriers between land and sea, owing to their capacity to effectively capture considerable quantities of terrestrial pollutants. Mangrove fragmentation has been a widespread global trend. There is limited information on the water quality status of these small scattered mangrove patches in coastal sub-developed areas, coupled with a paucity of efficient and intuitive assessment methodologies. To address this gap, the Water Quality Index (WQI) was introduced to evaluate the spatiotemporal characteristics of mangrove water quality. The major sources of pollution and anthropogenic activities that affect mangrove water quality were identified. The results revealed an average WQI value of 44.1 ± 13.3 for mangrove patches, consistently indicating a "low" water quality classification throughout all seasons. Both the size and natural conditions impact the water quality of mangroves. The large artificial patch (WQI: 56.4 ± 7.61) and the natural patch (WQI: 46.6 ± 13.6) exhibited relatively superior water quality, while the WQI value of a size-equivalent artificial patch compared with the natural patch is 38.6 ± 11.8. Aquaculture was the primary human activity that adversely affected the water quality of mangroves, and the potential sources of pollution were rainfall runoff and river discharge. These findings elucidate the unfavorable water quality characteristics and dominant pollution of fragmented mangroves, and validate the applicability of the WQI method for long-term evaluation of the water quality in mangrove patches. This study provides a basis for decision-making in water quality assessment and management of coastal wetlands and marine ecosystems. Scientific guidance to the management for mangrove protection and restoration was offered, such as regulating aquaculture activities, controlling non-point source pollution, implementing mangrove reforestation by using native species in historical mangrove sites.

Multi-biomarker approach for the (eco)toxicity of UV-filter environmental pollution on the Mediterranean mussel Mytilus galloprovincialis in a multiple stressor context. The case of 4-MBC under salinity shifts.

Marine-coastal ecosystems are rapidly transforming because of climate change (CC). At the same time, the impacts of emerging organic contaminants (i.e., organic UV-filters) on these ecosystems are intensifying. In the Mediterranean, the consequences of these disturbances are occurring at a fast pace making this area a potential sentinel site to be investigated. While singular effects of organic UV-filters or CC-related factors on marine biota have been relatively described, their combined impact is still largely unknown. Thus, the objective of this study was to assess the long-term responses of the Mediterranean mussel Mytilus galloprovincialis towards anticipated salinity changes (decreases-S20 or increases-S40) when exposed to environmentally relevant concentrations of the UV-filter 4-methylbenzylidene camphor (4-MBC). An integrated multi-biomarker approach was applied, featuring general and oxidative stress, antioxidant and biotransformation enzyme capacity, energy metabolism, genotoxicity, and neurotoxicity biomarkers. Results showed that both projected salinities, considered separately, exerted non-negligible impacts on mussels' health status, with greater biological impairments found at S 40. Combining both stressors resulted in an evident increase in mussels' susceptibility to the UV-filter, which exacerbated the toxicity of 4-MBC. The dominant influence of salinity in the climate change-contaminant interaction played a crucial role in this outcome. The most severe scenario occurred when S 20 was combined with 4-MBC. In this situation, mussels exhibited a decrease in filtration rate, metabolic capacity and deployment of energy reserves increased, with an upregulation of biotransformation and inhibition of antioxidant enzyme activities. This exposure also led to the observation of cellular and DNA damage, as well as an increase in AChE activity. Furthermore, salinity-dependent bioaccumulation patterns were evaluated revealing that the lowest values in contaminated mussels are found at S 20. Overall, the present findings provide evidence that projected CC/pollutant scenarios may represent high risks for mussels’ populations, with global relevant implications for the ecosystem level.

Perception and Awareness of Marine Plastic Pollution in Selected Tourism Beaches of Barobo, Surigao del Sur, Philippines

Tourism is a significant economic activity in coastal communities, but when badly managed, it degrades the health of the marine-coastal ecosystem, increasing litter pollution and repels beach visitors. This study aims to assess the tourism impact on litter pollution on four growing tourism beaches of Barobo, Surigao del Sur, Philippines. Plastic litters were sampled from four tourism sites (Cabgan Island, Turtle Island, Dapdap Beach, Panaraga Beach) of Barobo by establishing transect lines with quadrats. Those who agreed to participate in perception and knowledge tests about marine debris were interviewed at the aforementioned beaches. Respondents was generally aware of marine pollution problems, specifically marine pollution relating to human and ecological health. Respondents identified tourism as a main litter source and plastic packaging as the most common litter type, which is true based on macrolitter collection. Because tourism causes plastic pollution on all of the beaches studied, stronger regulations, educational, and awareness efforts are crucial to reduce litter pollution and avert ecological and socioeconomic consequences.&#x0D; Structured Abstract: Purpose: Tourism plays a big role in the economic status of a country. It provides livelihood to the community and helps in poverty elevation. But tourism also brings pollution, i.e., plastic pollution, if not properly managed. The primary objective of this study is to evaluate the perception and awareness of tourists on plastic pollution and its impacts on tourism. &#x0D; Design/methodology/approach: The study was limited to surveys and key informant interviews (KII) since fora and assemblies are not allowed due to pandemic health protocols. Survey sampling was done simultaneously with the macroplastic collection from July 10 to August 12, 2021. Convenience sampling design was used, and data was collected on willing individuals present in the area. The awareness questionnaire used the Likert Scale method, while the individual perception used multiple choice or open-ended questions. Statistical data analysis was performed using SPSS and Microsoft excel.&#x0D; Findings: A total of 105 willing individuals were legally part of this study. Of the 105 respondents surveyed, 70 of which are tourists from island beaches and 35 are from mainland beaches. Respondents were generally aware of most issues presented to them. The top issues that the respondents relate the most are related to plastic effects on health and environment. The majority of the surveyed tourists on island beaches perceived high macrolitter pollution, while those on mainland beaches perceived low pollution. This perception of respondents agrees with the litter quantities registered and collected. Furthermore, the perception of plastic packaging as the most common type of litter has been found out to be true based on sampling collections. Tourists on the beaches of Barobo are aware of the problem of marine litter and see the tourism sector as a source of waste, notably plastics.&#x0D; Originality: This research paper submitted by us is an outcome of our independent and original work. We have duly acknowledged all the sources from which the ideas and extracts have been taken. The paper is free from any plagiarism and has not been submitted elsewhere for publication.&#x0D;

Influences of habitat and seasonal changes on gonadal maturation of Echinometra mathaei (Echinodermata: Echinoidea) and Tridacna squamosa (Mollusca: Bivalvia) in the Red Sea, Egypt

The present work is aimed at investigating the effects of seasonal changes and habitat conditions on reproductive state and gonadal development of two macrobenthic fauna. Echinometra mathaei and Tridacna squamosa were collected seasonally (summer and winter) in July 2019 and January 2020 from three sites along the Red Sea coast, Egypt: Hamraween, Sedy Malek, and Porto Ghalb. Sexual differences and gonadal maturation in the two species were determined by performing biopsies of their gonads followed by morphologic analyses. Hematoxylin and eosin–stained gonadal sections were examined and analyzed. In E. mathaei, reproductive behavior was more active in the summer than in the winter; in T. squamosa, reproductive behavior was active almost all the year, especially during the winter. The reproductive activity and gonadal maturation of both species were affected by environmental factors. The results indicated that temperature is a vital factor affecting the reproductive activity of both species. This study concluded that temperature fluctuations may pose significant challenges to coastal marine ecosystems.

Marine coastal biodiversity and services in Ireland in a three-dimensional context: Scientific, news media, and legislative

Biodiversity is a key indicator of ecosystem health and plays an important role in providing ecosystem services that are essential for economic development and social well-being. In Ireland, climate change and anthropogenic pressures have led to biodiversity loss and habitat degradation, which in turn affects the provision of ecosystem services. The aim of this study was to determine how marine coastal biodiversity and ecosystem services in the Republic of Ireland are portrayed in the scientific literature, news media, and current legislation in order to identify knowledge gaps and priority areas of intervention for policymakers and other decision-making stakeholders. A review of the scientific literature based on the Scopus database suggests a lack of stakeholder involvement in the scientific-based approach. Up to 2022 research on marine coastal biodiversity focused primarily on species richness and diversity, especially in the context of climate change, while research on ecosystem services focused primarily on ecosystem function. Analysis of the news media found that coverage of biodiversity and ecosystem services has increased over the past decade, but opportunities are being missed to raise public awareness of the multiple benefits, not just economic, of marine coastal ecosystems, their biodiversity, and the services they provide. The terms “biodiversity” and “ecosystem services” have only been introduced into Irish legislation in recent years. The legislative context at the national level is rather fragmented at diverse levels and mainly corresponds to the transposition of European Directives while national specific legislation is less developed. The interconnection between these three domains: scientific, news media and legislative was not evident in this study, especially in the case of the scientific field. Efforts to promote science-based knowledge, communication, collaboration, and transparency between these domains are crucial to support informed decision-making and promote public engagement while conserving biodiversity. Addressing the information gaps identified in this work could help advance the implementation of Nature-based Solutions (NbS), key cost-effective measures to mitigate and adapt to the impacts of climate change while protecting biodiversity and ecosystem services.

Management approaches to conserve Australia's marine ecosystem under climate change.

Australia's coastal marine ecosystems have a deep cultural significance to Indigenous Australians, include multiple World Heritage sites, and support the nation's rapidly growing blue economy. Yet, increasing local pressures and global climate change are expected to undermine the biological, social, cultural, and economic value of these ecosystems within a human generation. Mitigating the causes of climate change is the most urgent action to secure their future; however, conventional and new management actions will play roles in preserving ecosystem function and value until that is achieved. This includes strategies codeveloped with Indigenous Australians that are guided by traditional ecological knowledge and a modeling and decision support framework. We provide examples of developments at one of Australia's most iconic ecosystems, the Great Barrier Reef, where recent, large block funding supports research, governance, and engagement to accelerate the development of tools for management under climate change.

Marine heatwave temperatures enhance larval performance but are meditated by paternal thermal history and inter-individual differences in the purple sea urchin, Strongylocentrotus purpuratus.

Marine heatwave (MHW) events, characterized by periods of anomalous temperatures, are an increasingly prevalent threat to coastal marine ecosystems. Given the seasonal phenology of MHWs, the full extent of their biological consequences may depend on how these thermal stress events align with an organism's reproductive cycle. In organisms with more complex life cycles (e.g., many marine invertebrate species) the alignment of adult and larval environments may be an important factor determining offspring success, setting the stage for MHW events to influence reproduction and development in situ. Here, the influence of MHW-like temperatures on the early development of the California purple sea urchin, Strongylocentrotus purpuratus, were explored within the context of paternal thermal history. Based on temperature data collected during MHW events seen in Southern California from 2014-2020, adult urchins were acclimated to either MHW or non-MHW temperatures for 28days before their sperm was used to produce embryos that were subsequently raised under varying thermal conditions. Once offspring reached an early larval stage, the impact of paternal and offspring environments were assessed on two aspects of offspring performance: larval size and thermal tolerance. Exposure to elevated temperatures during early development resulted in larger, more thermally tolerant larvae, with further influences of paternal identity and thermal history, respectively. The alignment of paternal and offspring exposure to MHW temperatures had additional positive benefits on larval thermal tolerance, but this tolerance significantly decreased when their thermal experience mismatched. As the highest recorded temperatures within past MHW events have occurred during the gametogenesis of many kelp forest benthic marine invertebrate species, such as the purple sea urchin, such parental mediated impacts may represent important drivers of future recruitment and population composition for these species.

Biomonitoring of Benthic Organisms for Coastal Protection: A Checklist Study from Pantai Remis and Blue Lagoon on the West Coast of Peninsular Malaysia

The objective of the study was to provide an updated checklist of benthic marine organisms in Pantai Remis (Selangor) and Blue Lagoon (Negeri Sembilan) in November 2022. The research areas comprised a total of 26 species of marine benthic organisms, which were divided into 12 orders, 18 families, and 22 genera. Benthic macrophytes formed the largest group (11 species), followed by other benthic macrofauna (molluscs, with eight species). In addition, three coral species, two gastropods, and two crabs were also recorded. The findings revealed that both sites are fertile and suitable habitats for marine benthic organisms. The established checklist of benthic organisms can serve as an ongoing basis for future reference as part of our efforts to develop coastal marine ecosystem management and conservation on the west coast of Peninsular Malaysia. In summary, the checklist of benthic organisms provides the basic information that is much needed for the protection of coastal ecosystems.

Silicon composition and stoichiometric ratios with other nutrients in the lower Minjiang River, Southeast China.

Over the past decades, rivers have delivered imbalanced nutrient loads to coastal marine ecosystems due to human activities, which leads to serious regional or global eutrophication problems. The Minjiang River is heavily influenced by human activities. To understand the changing characteristics of nutrient transport ratios in the Minjiang River waters, we measured the seasonal variations of carbon, nitrogen, phosphorus and silicon nutrients in the lower surface waters of the Minjiang River between July 2019 and July 2020. The results showed that the annual average contents of dissolved silicon (DSi), lithogenic silicon (LSi) and biogenic silicon (BSi) in the surface waters of the lower Minjiang River were 5.30, 4.58 and 2.37 mg·L-1, respectively. There were large seasonal differences among these parameters, with higher content of DSi than LSi and BSi in summer, higher content of DSi than BSi and LSi in autumn and higher content of LSi than DSi and BSi in winter. The proportions of DSi in total silicon tended to decrease gradually from land to sea, while the proportion of BSi was on the contrary. In term of stoichiometric ratios, the Minjiang River mostly presented carbon or phosphorus limitation and was unlimited by silicon or nitrogen. About 1.03×1010 mol DSi and 0.46 ×1010 mol BSi were delivered via the Minjiang River to the ocean yearly, showing a decreasing trend year by year. Based on the data in recent years, the nutrient loads of carbon, nitrogen, and phosphorus transported by Minjiang River showed an increasing trend. The imbalanced nutrient loads may lead to changes in the structure and function of the river, estuary, and offshore ecosystems. The study of nutrient stoichiometric ratios can provide a theoretical basis for solving the problems in structural balance of nutrients and eutrophication in Minjiang River estuary and adjacent marine waters.

Positive effects of two decades of passive ecological restoration in a historically polluted marine site

The Mediterranean Sea is one of the most exploited regions of the world’s oceans. Here industrial activities have determined either acute or long-term impacts on coastal marine ecosystems. In this study, we investigated macrofauna distribution and diversity, and food-web functioning in a coastal area of the Mediterranean Sea facing an industrial chemical plant abandoned in the ‘90s to assess benthic ecosystem health. This area has been identified as a Site of National Interest (SNI) since 2002 and has been closed to any human activity awaiting to be remediated according to national laws. Our results indicate that, two decades after the SNI declaration (a decade after the plant decommissioning), there is no longer any sign of the impact of historical contaminations on macrofauna and benthic food web functioning. Overall, all the thirty-six sites showed high/good ecological quality according to the score assigned by AMBI and M-AMBI indexes, reflecting the absence of chronic impacts. Our findings reveal, for the first time, the positive effects of passive restoration (i.e., unassisted, or spontaneous recovery following cessation of anthropogenic impacts) on historically impacted coastal ecosystems since their health conditions, in terms of both abiotic (environmental variables and contaminant concentration) and biotic (macrofauna diversity and community composition, and benthic food-web structure) factors, were indistinguishable from surrounding non-impacted areas. These findings also suggest that other effective area-based conservation measures (OECMs) could be useful not only for biodiversity conservation of vulnerable and priority habitats in larger ocean sectors but also to promote the passive recovery of historically contaminated ecosystems.