Healthy Marine Ecosystems Research Articles

Declining population of Harlequin Duck (<i>Histrionicus histrionicus</i>) on the Bow River, Alberta, Canada: 25 years of monitoring

Harlequin Duck (Histrionicus histrionicus) is a small sea duck that winters in coastal waters and breeds on fast-movingmountain streams in western North America. Because of its dependency on streams and coastal near-shore habitat with healthy macroinvertebrate populations, population trends of this species can be used as an indication of healthy freshwater and marine ecosystems. From 1995 to 2020 we conducted roadside surveys for Harlequin Ducks on the Bow River in Banff National Park, Alberta. We calculated the population’s trend by modelling maximum annual count, which showed a population decline over the 25 years of 3.3% per year. The trajectory varied over time: a relatively stable population from 1995 to 2005, a steep decline until 2011, then stabilising at a much lower level with a slight rebound in recent years. The predicted number of ducks from our state-space model closely tracked the maximum number of ducks observed in annual counts. During stable or slightly increasing population estimates the male:female (M:F) ratio fluctuated considerably but stayed high (1.4:1 and 1.3:1, respectively), and during the period of steep population decline the M:F ratio was at its lowest (1.1:1). This declining population trend is concerning because it is occurring in a protected area, but it is similar to data from other studies in the Rocky Mountains and at the coastal wintering area, suggesting that causes may not be solely due to issues on the breeding streams.

PETRI-MED: Enhancing marine phytoplankton diversity monitoring in the Mediterranean

PETRI-MED: Enhancing marine phytoplankton diversity monitoring in the Mediterranean Preserving biodiversity is crucial for sustaining life on Earth. Unfortunately, it is facing growing threats. Marco Talone and the PETRI-MED Team discuss their objectives for the PETRI-MED project and explain why it is urgently necessary. Marine biodiversity is crucial for maintaining healthy and resilient ecosystems. The variety of life forms in our oceans—from microscopic plankton to giant whales—plays a key role in sustaining ecological balance. Each species contributes to ecosystem services such as oxygen production, carbon sequestration, and nutrient cycling, which are vital for the planet’s health. Marine biodiversity also supports the global food web, providing a primary source of protein for over three billion people. Additionally, it contributes to the blue economy through fisheries, tourism, and biotechnology. Lastly, healthy marine ecosystems are better equipped to withstand and recover from environmental changes and human impacts, such as climate change and pollution. Among the various life forms inhabiting our ocean, phytoplankton is one of the most important.

The answer, my friend, is blowin' in the wind: Blow sampling provides a new dimension to whale population monitoring.

Marine mammals play a fundamental role in the functioning of healthy marine ecosystems and are important indicator species. Studying their biology, distributions, behaviour and health are still technically and logistically demanding for researchers. However, the efforts and commitment have not been in vain, since we are witnessing constant and exponential advancement in the study of these animals, thanks to technological progress in numerous fields. These include miniaturization and performance of biologger tags, which are equipped with sensors for measuring physiological parameters, hydrophones, accelerometers, time-depth records and spatial locations; the use of high throughput 'Next Generation' Sequencing to gain genetic information about communities and individual species from nucleic acids in environmental samples at miniscule concentrations; through, to the possibility of monitoring species with autonomous aerial and underwater vehicles. In parallel advances in computing and statistical modelling frameworks support the analysis of increasingly large and complex data sets. In this issue, O'Mahony etal.(2024) draw from at least two of these innovations: (a) the collection of biological material retrieved from large whales' blows using a modified drone and (b) the use of the samples to infer a wide spectrum of genetic information (both nuclear and mitochondrial) about the target animal/population. The methodology is not completely novel, but the study shows an impressive advancement in the amount of data obtained compared to preceding studies using the same approach. In the wake of these promising results, future perspectives are evaluated in relation to alternative sampling methodologies currently in use. It is possible to speculate that, in the next few years, the combination of non-invasive molecular profiling and enhanced drone technology (e.g. assembling increasingly smaller components, thus expanding capacity for autonomous operation) will open up perspectives that were unimaginable at the beginning of this millennium.

A framework for assessing the blue equity of social-ocean systems in marine governance transformation

The equitable utilization of marine resources and the maintenance of healthy and sustainable marine ecosystems are essential to advancing the United Nations Sustainable Development Goals (SDGs) and promoting the well-being of all humanity. In this paper, we propose a Blue Equity Assessment Framework, which is based on a systematic literature review approach and takes into account the characteristics of Social-Ocean Systems (SOSs). The framework consists of Distributional Equity, Procedural Equity, Recognitional Equity, and Contextual Equity. The aim of this framework is to conduct equity analyses of policies or behaviors within SOSs in order to assess whether blue equity is explicitly implemented and practiced in these societal norms and policy mechanisms. The assessment framework reveals that blue equity has a positive synergy for the majority of the SDGs. This synergy is analyzed in terms of its influence on the assessment dimensions of distributional justice, procedural justice, recognitional justice, and contextual justice. The findings aim to enhance societal understanding of blue equity issues, thereby guiding policymakers in the prioritization of blue equity in the development and utilization of marine resources and in the transformation of global ocean governance.

Physical Experiments Of Wave Attenuation Over Submerged Shellfish Reefs

Globally and across Australia shellfish reef ecosystems have become critically endangered due to decades of overfishing, pollution and dredging (e.g., Beck et al., 2011). In response, the Australian federal government, in partnership with The Nature Conservancy, committed to restoring 60 shellfish reef ecosystems across Australia by building reefs from limestone and recycled shells scattered with juvenile oysters or mussels. Although the primary aim is to promote healthy marine ecosystems and biodiversity, there are strong indications that these restored shellfish reefs may also substantially dissipate ocean waves and provide protection against coastal flooding. Analogies have been drawn with conventional engineering structures (submerged breakwaters, e.g. Dattatri et al., 1978) as well as nearshore shellfish reefs increasingly considered as a nature-based method for coastal resilience against flooding (“living shorelines”, see e.g. Morris et al., 2021). Although the currently restored reefs do present clear similarities, they also have distinct differences that raise questions to whether they can be as effective in dissipating wave energy. Observational data from laboratory or field to verify this is currently lacking. This study aims to quantify the effectiveness of multiple parallel submerged reef structures in relatively deep water in dissipating wave energy. Experiments (1:10 scale) were carried out in a 54-m-long wave flume using 3 reef designs that vary in reef spacing, width and height, representative for shellfish reef ecosystems as recently restored and established across Australia and the US. All designs were subjected to two water depths (0.7 and 1 m on laboratory scale) and 8 (irregular) wave conditions covering 4 peak wave periods and significant wave heights ranging from 0.1 to 0.3 m (lab scale). For the cases with 0.7 m water depth, wave height reduction varied from 10 to 23%, while for the cases with 1 m water depth wave heights generally decreased slightly up to about 5%. The reefs were found to be particularly effective in reducing the largest waves within the timeseries that would have the highest potential of causing coastal impact (e.g., flooding or erosion). In addition, observations obtained with an Acoustic Doppler Velocimeter showed up to 45% reduction of near-bed orbital (rms) velocities, highlighting the potential for these structures to benefit seagrass restoration efforts. Overall, the results of this study show that restored shellfish reefs can reduce incident wave energy and orbital velocities considerably, in particular for relatively high waves in relatively shallow water, and have the potential to be considered in nature-based coastal defense strategies.

Insights into carbonate environmental conditions in the Chukchi Sea

Abstract. Healthy Arctic marine ecosystems are essential to the food security and sovereignty, culture, and wellbeing of Indigenous Peoples in the Arctic. At the same time, Arctic marine ecosystems are highly susceptible to impacts of climate change and ocean acidification. While increasing ocean and air temperatures and melting sea ice act as direct stressors on the ecosystem, they also indirectly enhance ocean acidification, accelerating the associated changes in the inorganic carbon system. Yet, much is to be learned about the current state and variability of the inorganic carbon system in remote, high-latitude oceans. Here, we present time series (2016–2020) of pH and the partial pressure of carbon dioxide (pCO2) from the northeast Chukchi Sea continental shelf. The Chukchi Ecosystem Observatory includes a suite of subsurface year-round moorings sited amid a biological hotspot that is characterized by high primary productivity and a rich benthic food web that in turn supports coastal Iñupiat, whales, ice seals, walrus (Odobenus rosmarus), and Arctic cod (Boreogadus saida). Our observations suggest that near-bottom waters (33 m depth, 13 m above the seafloor) are a high carbon dioxide and low pH and aragonite saturation state (Ωarag) environment in summer and fall, when organic material from the highly productive summer remineralizes. During this time, Ωarag can be as low as 0.4. In winter, when the site was covered by sea ice, pH was <8 and Ωarag remained undersaturated under the sea ice. There were only two short seasonal periods with relatively higher pH and Ωarag, which we term ocean acidification relaxation events. In spring, high primary production from sea ice algae and phytoplankton blooms led to spikes in pH (pH > 8) and aragonite oversaturation. In late fall, strong wind-driven mixing events that delivered low-CO2 surface water to the shelf also led to events with elevated pH and Ωarag. Given the recent observations of high rates of ocean acidification and a sudden and dramatic shift of the physical, biogeochemical, and ecosystem conditions in the Chukchi Sea, it is possible that the observed extreme conditions at the Chukchi Ecosystem Observatory are deviating from the carbonate conditions to which many species are adapted.

Marine diseases and the Anthropocene: Understanding microbial pathogenesis in a rapidly changing world.

Healthy marine ecosystems are paramount for Earth's biodiversity and are key to sustaining the global economy and human health. The effects of anthropogenic activity represent a pervasive threat to the productivity of marine ecosystems, with intensifying environmental stressors such as climate change and pollution driving the occurrence and severity of microbial diseases that can devastate marine ecosystems and jeopardise food security. Despite the potentially catastrophic outcomes of marine diseases, our understanding of host-pathogen interactions remains an understudied aspect of both microbiology and environmental research, especially when compared to the depth of information available for human and agricultural systems. Here, we identify three avenues of research in which we can advance our understanding of marine disease in the context of global change, and make positive steps towards safeguarding marine communities for future generations.

The Ongoing Battle: Understanding the Population Trends of Green Turtles in Peninsular Malaysia

Sea turtles are crucial marine animals. They act as indicator to a healthy marine ecosystem. However, they are subjected to different challenges and threats which results of their declining population. This study looks at the population trends of sea turtles in Malaysia by examining the numbers of nests, eggs, and hatchlings in six states in Peninsular Malaysia which are Perak, Pahang, Melaka, Johor, Terengganu, and Negeri Sembilan. Statistical distribution, hatching success percentage, trend landing and hatching, and linear regression analysis are implemented. The results show that Terengganu, on the east coast, consistently has the highest numbers of nests, eggs, and hatchlings, highlighting its key role in sea turtle conservation. In contrast, Melaka has the lowest numbers, pointing where conservation efforts could be increased. This study provides valuable insights into the differences in green turtle populations across states and identifies critical areas for focused conservation strategies to better protect and help these endangered species recover in Malaysia.

Perspectives and Scenarios for Coastal Fisheries in a Social-Ecological Context: An Ecosystem Service Assessment Approach in the German Baltic Sea

Worldwide, fisheries have experienced change over time. An excess of exploitation for providing food has led to overfishing and the depletion of fish stocks. However, fishing communities are also part of the cultural heritage and contribute to the attractiveness of coastal areas to tourists. Our aim is to identify if ecosystem service assessments (ESA) can reflect the condition of fisheries and their economic and social aspects. We developed a tailored, expert-based ESA and applied it to two case studies in the eastern German Baltic Sea under different fishery management scenarios. The results show that reducing fishing pressure, actively restoring habitats, and improving their ecological status increase the provision of most ecosystem services. We discuss and conclude that ESAs allow for a holistic view on fisheries that goes beyond the economic importance of fisheries and shows both the interdependence between fisheries and healthy marine ecosystems, and their relevance for coastal communities. Such a holistic view is necessary for a sustainable approach to fisheries management. Our approach is easily transferable to other regions, and can be used to structure discussion on fisheries management scenarios, as well as to track and visualize societal changes.

Bycatch Mitigation Strategies in the Gulf of Alaska

Commercial fishing is a crucial industry in Alaska’s economy, but unsustainable fishing practices, especially bottom trawling, lead to excessive bycatch and economic discards. This poses a major threat to marine ecosystems and their biodiversity, which puts the resources within Alaska’s fisheries at risk of diminishing to a point where they cannot meet human demand. Through extensive research and evaluation of this issue and existing legislation that governs Alaska’s fisheries, we recommend the full implementation of two specific measures across all of Alaska’s fisheries. One is electronic monitoring on all vessels in the form of deep learning cameras, and the other is a “freeze the footprint” approach on bottom trawling, which protects key seafloor habitats within the existing area that has been damaged by previous trawling activity. These efficient methods are a safer alternative to on-site observation, and they will lead to a healthier seafloor ecosystem, which is essential for marine life. Alaskan communities rely on their fisheries, and maintaining healthy marine ecosystems is critical to economic stability.

Research on environmental management of domestic wasteincineration fly ash and high salt water discharge into the sea

In our comprehensive management proposal for fly ash washing wastewater discharge into the sea, we establishstringent control measures across four categories: general elements, nutrients, heavy metals, and organic pollutants. Ourapproach is rooted in respect for and compliance with national and international pollution control standards. We definethe acceptable parameters for pH, salinity, and the content of Chemical Oxygen Demand (COD), suspended solids, totalnitrogen, ammonia nitrogen, phosphates, various heavy metals, and organic pollutants. Our plan includes thoroughlytreating wastewater, emphasizing the removal of lead, desalination, effective precipitation, and filtering processes beforethe wastewater is discharged into the sea. We advocate for constant surveillance and stringent management practicesto maintain a healthy marine ecosystem. Moreover, we acknowledge the need for additional biological testing in actualwork to more scientifically and comprehensively understand the potential impact of the discharged wastewater onmarine ecology. Our overall goal is to ensure that the potential environmental effects of fly ash washing wastewater areminimized while adhering to the highest environmental management standards.

A review of new and existing non-extractive techniques for monitoring marine protected areas

Ocean biodiversity loss is being driven by several anthropogenic threats and significant efforts are required to halt losses and promote healthy marine ecosystems. The establishment of a network of Marine Protected Areas (MPAs) can help restrict damaging activities and have been recognised as a potential solution to aid marine conservation. When managed correctly they can deliver both ecological and socio-economic benefits. In recent times, MPA designations have increased rapidly while many countries have set future MPA targets for the decades ahead. An integral element of MPA management is adequate monitoring that collects data to assess if conservation objectives are being achieved. Data acquired by monitoring can vary widely as can the techniques employed to collect such data. Ideally, non-destructive and non-invasive methods are preferred to prevent damage to habitats and species, though this may rule out a number of traditional extractive sampling approaches such as dredges and trawls. Moreover, advances in ocean observation technologies enable the collection of large amounts of data at high resolutions, while automated data processing is beginning to make analyses more logistically feasible and less time-consuming. Therefore, developments to existing marine monitoring techniques and new emerging technologies have led to a diverse array of options when choosing to implement an MPA monitoring programme. Here, we present a review of new and existing non-extractive techniques which can be applied to MPA monitoring. We summarise their capabilities, applications, advantages, limitations and possible future developments. The review is intended to aid MPA managers and researchers in determining the suitability of available monitoring techniques based on data requirements and site conditions.

Evaluating potential changes to the US Chukchi Sea bottom trawl survey design via simulation testing

The US Chukchi Sea consists of the waters off the northwest of Alaska and is a naturally dynamic ice-driven ecosystem. The impacts from climate change are affecting the Arctic marine ecosystem as well as the coastal communities that rely on healthy marine ecosystems. In anticipation of increased ecosystem monitoring in the area, there is an opportunity to evaluate improved sampling designs for future ecological monitoring of the Chukchi Sea, an area that is sampled less comprehensively compared to other regions in Alaska. This analysis focused on standardized NOAA-NMFS-AFSC bottom trawl surveys (otter and beam trawls) and three types of survey designs: simple random, stratified random, and systematic. First, spatiotemporal distributions for 18 representative demersal fish and invertebrate taxa were fitted using standardized catch and effort data. We then simulated spatiotemporal taxon densities to replicate the three survey design types to evaluate design-based estimates of abundance and precision across a range of sampling effort. Modest increases in precision were gained from stratifying the design when compared to a simple random design with either similar or lower uncertainty and bias of the precision estimates. There were often strong tradeoffs between the precision and bias of the systematic estimates of abundance (and associated variance) across species and gear type. The stratified random design provided the most consistent, reliable, and precise estimates of abundance indices and is likely to be the most robust to changes in the survey design. This analysis provides a template for changing bottom trawl survey designs in the Chukchi Sea and potentially other survey regions in Alaska going forward and will be important when integrating new survey objectives that are more ecosystem-focused.

Science Priorities for Offshore Wind and Fisheries Research in the Northeast U.S. Continental Shelf Ecosystem: Perspectives from Scientists at the National Marine Fisheries Service

AbstractOffshore wind development (OWD) is set to expand rapidly in the United States as a component of the nation's effort to combat climate change. Offshore wind development in the United States is slated to begin in the Greater Atlantic region, where it is expected to interact with ocean ecology, human dimensions, fisheries data collections, and fisheries management. Understanding these interactions is key to ensuring the coexistence of offshore wind energy with sustainable fisheries and a healthy marine ecosystem. These anticipated interactions compelled the authors, all fisheries scientists or managers at National Oceanic and Atmospheric Administration (NOAA) Fisheries who are actively engaged in offshore wind science to identify scientific research priorities for OWD in the Northeast U.S. Continental Shelf ecosystem, specifically in support of NOAA Fisheries' role as the nation's leading steward of marine life. We extracted and analyzed OWD research needs from existing scientific documents and used this information as the basis to develop a list of priorities that align with five major OWD science themes that are of high interest to NOAA Fisheries. These NOAA Fisheries themes include supporting the regulatory process; mitigating the impacts to NOAA Fisheries' surveys; advancing science to understand interactions with NOAA Fisheries trust resources, the marine ecosystem, and fishing industries/communities; advancing the science of mitigation for NOAA Fisheries trust resources and fishing industries/communities; and advancing data management methods. The areas identified as research priorities will support the coexistence of offshore wind and sustainable fisheries and inform the development of NOAA Fisheries' science plan for offshore wind in the Northeast U.S. Continental Shelf ecosystem as well as cross‐sectoral science planning efforts at the regional, national, and international levels.

Documenting historical changes in shark fisheries near Islas Marías, Mexico, using fishers' local ecological knowledge

Many shark species and populations are threatened globally due to human actions. Protecting these top predators is crucial to maintaining healthy marine ecosystems; however, for many habitats, long-term, historical datasets necessary to track population changes are lacking. In Islas Marías, Mexico, where shark fishing has occurred for decades, data on landings by species remain unavailable and the presence of a prison in the archipelago from 1905 to 2019 has hindered monitoring efforts. We used a synthesis of fishers’ local ecological knowledge (LEK) to address this knowledge gap about changes in shark populations near Islas Marías. Using LEK documented from interviews with 82 fishers, we cataloged shark species diversity, catch, and perceived relative abundance in the region. Fishers reported the presence of 15 species and one genus of sharks near Islas Marías. Overall, catch sizes and perceived relative abundance trends derived from interviews suggest that populations of sharks near Islas Marías have been in decline since at least the 1960 s. Interview participants attributed shark declines to environmental, social, and market factors. These results highlight the importance of fishers’ expert knowledge in reconstructing species population trends.

Blue economy investment and sustainability of Ghana’s territorial waters: an application of structural equation modelling

ABSTRACT Despite the fact that Blue Economy Investment (BEI) contributes immensely towards sustainable use of marine resources for economic growth, improved livelihoods, employment and healthy marine ecosystem, little efforts have been made to encourage sustainable investment in this area. In Ghana, the Marine Pollution Act 2016 (Act, 932) was promulgated to prevent, regulate and control pollution within Ghana’s territorial waters. Meanwhile, the health of Ghana’s oceans keeps deteriorating. This paper aims to develop an integrative model to enhance BEI through Sustainable Supply Chain Performance (SSCP) by integrating competing theories to attract sustainable investment to conserve and make sustainable use of marine resources. We anchored our study on quantitative research approach and a cross-sectional survey data. Our hypotheses have been tested using variance-based Structural Equation Modeling and SMART-PLS version 3.3.1. The study has revealed that organisational factors, technological factors, supply chain risk, green environmental awareness, perceived cost and regulatory environment are significant determinants of BEI. Moreover, BEI significantly drives SSCP. Again, BEI significantly mediates the relation between its determinants and SSCP. The implications include the emergence of an integrated model which could be used to improve marine resources investment and the realisation of Sustainable Development Goals 3, 13 and 14.

Assessing and managing charismatic marine megafauna in Palau: Bumphead parrotfish (Bolbometopon muricatum) and Napoleon wrasse (Cheilinus undulatus)

Abstract Bumphead parrotfish (Bolbometopon muricatum) and Napoleon wrasse (Cheilinus undulatus) are large, charismatic species with high economic and cultural value in Palau and are important for ecosystem function. As a result of intense fishing pressure, landings in Palau for both species declined dramatically in the 1990s and, in response, national legislation was enacted in 2006 that imposed a total ban on the extraction, possession, and sale of both species. In 2013 and 2021, fisheries‐independent stock assessments were conducted and found that the spawning potential ratios (SPRs) for bumphead parrotfish increased slightly from 30% to 34%. Conversely, the SPRs for Napoleon wrasse declined from 12% in 2013 to 4% in 2021. Despite the fishery being closed since 2006, these data suggest the likelihood of significant poaching, resulting in low SPR values, particularly for Napoleon wrasse. Prior to the COVID‐19 pandemic, marine tourism played a central role in the economic and social life of Palau. A willingness‐to‐pay survey found that divers would pay $1.27 million (2020 USD) more for strictly managed catches of both species, and nearly $3.00 million more if the fishery remained closed. The total market value for bumphead parrotfish peaked in 1995 at $112,190. The peak total market value for Napoleon wrasse was $66,434 in 2002. The welfare gain/loss for diver tourism is an order of magnitude greater than the fishery market gain/loss, and healthy marine ecosystems are essential for the post‐COVID‐19 economic recovery of Palau. However, because of the cultural importance of these species, there is a desire to manage this fishery for customary use. Opening a general subsistence harvest season is not recommended ecologically; however, the results suggest that if the SPR of bumphead parrotfish can recover to 40%, a limited quota of individuals with a total length of >95 cm could be sustained, which could be allocated via lottery. However, the fishery for Napoleon wrasse should remain closed given the extremely low SPR values and limited number of large adults in the population.

Preliminary study of shark microbiota at a unique mix-species shark aggregation site, in the Eastern Mediterranean Sea.

Sharks, as apex predators, play an essential ecological role in shaping the marine food web and maintaining healthy and balanced marine ecosystems. Sharks are sensitive to environmental changes and anthropogenic pressure and demonstrate a clear and rapid response. This designates them a "keystone" or "sentinel" group that may describe the structure and function of the ecosystem. As a meta-organism, sharks offer selective niches (organs) for microorganisms that can provide benefits for their hosts. However, changes in the microbiota (due to physiological or environmental changes) can turn the symbiosis into a dysbiosis and may affect the physiology, immunity and ecology of the host. Although the importance of sharks within the ecosystem is well known, relatively few studies have focused on the microbiome aspect, especially with long-term sampling. Our study was conducted at a site of coastal development in Israel where a mixed-species shark aggregation (November-May) is observed. The aggregation includes two shark species, the dusky (Carcharhinus obscurus) and sandbar (Carcharhinus plumbeus) which segregate by sex (females and males, respectively). In order to characterize the bacterial profile and examine the physiological and ecological aspects, microbiome samples were collected from different organs (gills, skin, and cloaca) from both shark species over 3 years (sampling seasons: 2019, 2020, and 2021). The bacterial composition was significantly different between the shark individuals and the surrounding seawater and between the shark species. Additionally, differences were apparent between all the organs and the seawater, and between the skin and gills. The most dominant groups for both shark species were Flavobacteriaceae, Moraxellaceae, and Rhodobacteraceae. However, specific microbial biomarkers were also identified for each shark. An unexpected difference in the microbiome profile and diversity between the 2019-2020 and 2021 sampling seasons, revealed an increase in the potential pathogen Streptococcus. The fluctuations in the relative abundance of Streptococcus between the months of the third sampling season were also reflected in the seawater. Our study provides initial information on shark microbiome in the Eastern Mediterranean Sea. In addition, we demonstrated that these methods were also able to describe environmental episodes and the microbiome is a robust measure for long-term ecological research.

Risk assessment of the extraordinary pollution in the Adriatic Sea as an economically important area for the Republic of Croatia

Risk assessment links the likelihood of adverse events occurring to their consequences. Such assessment is used in labour management and trade-off determination to identify the safety and impacts associated with a particular interest. In the maritime sector, it is mainly used to raise safety standards, prevent pollution, and maintain a healthy marine ecosystem. Risk control itself is traditionally focused on the relationships between individual actions and consequences, which are later considered in groups to assess their acceptability in accordance with safety requirements. Therefore, the risk assessment for the extraordinary pollution of the Adriatic Sea as an economically important area for the Republic of Croatia are described in this paper. First, the area of analysis is defined, and a meteorological description of the eastern Adriatic coast is provided. The risk assessment is carried out in three steps. The first step is a description of waterways, and the analysis of traffic density, regulations, and types of vessels in individual areas. The second step is a detailed analysis of statistical data on accidents in the Adriatic Sea. Finally, the most probable and the most undesirable extraordinary pollution events and their impact on the Croatian economy are analysed. In addition, examples and procedures for determining risk acceptability and its control in a part of the Croatian coast are presented.

Eutrophication, contaminants, litter and climate change: Baltic Sea under threat

Abstract The Baltic Sea is still impacted by numerous pressures. More efforts are needed to reduce them for achieving healthy and resilient marine ecosystems and their sustainable uses. This can only be reached through the cooperation of Baltic Sea states and strong regional governance. The HELCOM Baltic Sea Action Plan 2021 is the promising instrument to implement these efforts for the Baltic Sea and to advance the global objectives of marine protection.