Sea Ecosystem Research Articles

Investigating ecosystem connections in the shelf sea environment using complex networks

Abstract. We use complex network theory to better represent and understand the ecosystem connectivity in a shelf sea environment. The baseline data used for the analysis are obtained from a state-of-the-art coupled marine physics–biogeochemistry model simulating the North West European Shelf (NWES). The complex network built on model outputs is used to identify the functional groups of variables behind the biogeochemistry dynamics, suggesting how to simplify our understanding of the complex web of interactions within the shelf sea ecosystem. We demonstrate that complex networks can also be used to understand spatial ecosystem connectivity, identifying both the (geographically varying) connectivity length-scales and the clusters of spatial locations that are connected. We show that the biogeochemical length-scales vary significantly between variables and are not directly transferable. We also find that the spatial pattern of length-scales is similar across each variable, as long as a specific scaling factor for each variable is taken into account. The clusters indicate geographical regions within which there is a large exchange of information within the ecosystem, while information exchange across the boundaries between these regions is limited. The results of this study describe how information is expected to propagate through the shelf sea ecosystem, and how it can be used in multiple future applications such as stochastic noise modelling, data assimilation, or machine learning.

New insights into the Weddell Sea ecosystem applying a quantitative network approach

Abstract. Network approaches can shed light on the structure and stability of complex marine communities. In recent years, such approaches have been successfully applied to study polar ecosystems, improving our knowledge on how they might respond to ongoing environmental changes. The Weddell Sea is one of the most studied marine ecosystems outside the Antarctic Peninsula in the Southern Ocean. Yet, few studies consider the known complexity of the Weddell Sea food web, which in its current form comprises 490 species and 16 041 predator–prey interactions. Here we analysed the Weddell Sea food web, focusing on the species and trophic interactions that underpin ecosystem structure and stability. We estimated the strength for each interaction in the food web, characterised species position in the food web using unweighted and weighted food web properties, and analysed species' roles with respect to the stability of the food web. We found that the distribution of the interaction strength (IS) at the food web level is asymmetric, with many weak interactions and few strong ones. We detected a positive relationship between species median IS and two unweighted properties (i.e. trophic level and the total number of interactions). We also found that only a few species possess key positions in terms of food web stability. These species are characterised by high median IS, a middle to high trophic level, a relatively high number of interactions, and middle to low trophic similarity. In this study, we integrated unweighted and weighted food web information, enabling a more complete assessment of the ecosystem structure and function of the Weddell Sea food web. Our results provide new insights, which are important for the development of effective policies and management strategies, particularly given the ongoing initiative to implement a marine protected area (MPA) in the Weddell Sea.

Diversity and dynamics of tintinnids communities from Romanian Black Sea, in 2021

Tintinnids are tiny ciliates from microzooplankton that are very important due to their implication in the microbial food web and for the fact that in the last two decades a considerable number of non-indigenous species have entered and acclimatized in the Black Sea basin. The paper presents the species diversity and dynamic of microzooplanktonic tintinnids’ abundance as a result of two cruises carried out in May-June and August-September 2021, along the Romanian Black Sea coast. We identified 23 tintinnid species in total, with a higher diversity in the surface layer compared to those of depth. The species Eutintinnus sp. and Salpingella decurtata were found eclusively in the 10 m layer. Tintinnopsis cylindrica represented 74% of the mean biomass of tintinnid’s community from May-June, the best quantitative representation recorded in the Romanian coast's northern sector. Amphorellopsis acuta represented 91% of the mean biomass of tintinnid’s community in August-September. The biotic component was also correlated with temperature and salinity to give more information regarding spatial and temporal variations from one area to the other. The findings contribute to the knowledge of microzooplankton communities in the Romanian Black Sea region. The data on species composition, abundance distribution, and environmental correlations enhance our understanding of the ecological dynamics and potential ecological implications of tintinnid communities. This study brings valuable information to the understanding of the microzooplankton component in the Black Sea ecosystem.

Morphological analysis of resorption and degenerative processes in gonads of fishes — representatives of different families in reservoirs Dagestan part of the Middle Caspian Sea

In recent decades, the vulnerability of the Caspian Sea ecosystem has been observed due to large-scale anthropogenic impact. Due to the limited number of studies on resorption and degenerative processes in fish gonads, it was important to evaluate these regularities in commercial fish species — representatives of different families in the water bodies of the Dagestan part of the Middle Caspian Sea. In the process of our own research and analyzed literature data, the peculiarities and character of resorption passage when it is of mass character were revealed and the reasons causing it were established. In addition, the phases (stages) and conditions necessary for this process, its duration and irreversibility were studied. The biological significance of resorption has been established. Disturbances revealed in the external morphology of germ cells may be a predictor of profound changes in their structure and function. To clarify and elucidate the possibility of participation of individuals of the analyzed fish species in the spawning process with abnormal types of gonads, it is necessary to conduct a more detailed study of the sex glands at different levels of their organization, including cellular, tissue and organ levels. All the obtained factual data, regularities and revealed peculiarities in the reproductive processes in the studied species with different biology provide an opportunity for further scientific knowledge of all parts of the reproductive cycle in fish in different ecological conditions. We consider the revealed peculiarities of functioning of reproductive systems, mechanisms of adaptation of fishes to different conditions of existence as significant and necessary for solving many theoretical questions — in the field of morphofunctional and ecological analyses of evolutionary process, as well as such urgent practical problems as obtaining artificially full-fledged eggs and milk for fish breeding in pond conditions; for biologically justified exploitation of fish resources in natural reservoirs, which provide fish with high fecundity.

A chlorophyll a, non‐photochemical fluorescence quenching correction method for autonomous underwater vehicles in shelf sea environments

AbstractAutonomous underwater vehicles provide water column observations of phytoplankton biomass using chlorophyll a (Chl a) fluorometers. However, under high incident light, phytoplankton fluorescence yield decreases in a process known as non‐photochemical quenching, resulting in a reduced Chl a fluorescence signal. Methods have been developed to identify and remove the quenched signal from observations by autonomous underwater vehicles. These existing methods rely on assumptions of the homogeneity of the system, both in terms of time (i.e., between day and night observations) and space (i.e., within the water column or between neighboring profiles). These assumptions are not valid in shallow shelf seas or when sampling across different water masses. Thus, we evaluate six new quenching correction methods based on an existing ocean‐based method, but adapted for a continental shelf sea environment where the water mass changes between night and day observations. We have included two main changes to the existing method. First, we interpolate the unquenched, nighttime signal across the daytime observations and use this as a reference for correcting the quenched, daytime signal. Second, we explore the inclusion of a fluorescence quenching depth limit. By interpolating nighttime observations across daytime periods, the diel changes in non‐photochemical quenching were separated from the phytoplankton population changes. The proposed methods all show improved performance compared to existing approach. The methods presented here, and the approach used to evaluate them, are applicable in other shelf sea environments, enabling studies using autonomous Chl a fluorescence data across shelf sea ecosystems.

Critical periods in the marine life history of juvenile western Alaska chum salmon in a changing climate

Recent precipitous declines in western Alaska chum salmon Oncorhynchus keta returns followed unprecedented warming in the northern Bering Sea ecosystem. To better understand the role of anomalous events on the early marine ecology of juvenile chum salmon in the northern Bering Sea, we utilized time-series observations over a 17 yr period (2003-2019) of sea surface temperature (SST) and juvenile chum salmon size (length and weight), diet, energy density, and relative abundance. Particular attention was paid to more recent (2014-2019) years in which there was unprecedented loss of sea ice in the northern Being Sea in comparison to previous warm (2003-2005) and cold (2006-2013) periods. Our findings indicate significant correlations between SST and juvenile chum salmon relative biomass (positive) and energy density (negative). We found that juvenile chum salmon were larger during warm periods than during cold periods; however, there was no significant difference in their length and weight between the warm periods. Juvenile chum salmon fed on lower quality prey during warm periods than during cold periods, with an increase in the proportion of lower quality prey during the recent warm period. Consequently, the energy density of juvenile chum salmon was also lower during warm periods than during cold periods, with the lowest values occurring during the recent warm period (2014-2019). These results identify a shift in energy allocation and/or prey quality of juvenile chum salmon with temperature and illustrate how marine ecosystems have altered the nutritional condition of juvenile chum salmon prior to winter, when energy reserves are considered critical to survival.

When the “best available science” is not good enough: The need for supporting scientific research in the United Nations treaty to protect biodiversity beyond national jurisdiction

The distant ecosystems of the high seas are growing closer every year as humans create and deploy novel technologies to harvest resources from the open ocean. A new international agreement, the treaty for Biodiversity Beyond National Jurisdiction (BBNJ), is intended to ensure the conservation and sustainability of such ecosystems. Among other issue areas, the BBNJ agreement establishes requirements for conducting Environmental Impact Assessments (EIAs) for activities within (or impacting) Areas Beyond National Jurisdiction. This short communication argues that the EIA process created by the BBNJ treaty will not be effective at achieving the goals of conservation and sustainable use of marine biodiversity beyond national jurisdiction without strong scientific support. The basic problem is that EIAs require more information than what is available for even the most accessible marine ecosystems in Areas Beyond National Jurisdiction. We consider three cases of ocean uses – plastic cleanups, deep seabed mining, and mesopelagic fisheries – to demonstrate that available scientific knowledge is insufficient to conduct and evaluate informative EIAs. We suggest three ways that the Scientific and Technical Body established by the BBNJ agreement could be augmented by the Conference of Parties in order to help avoid dysfunction in the EIA process, support scientific discovery, and increase environmental protection.

Automated identification of invasive rabbitfishes in underwater images from the Mediterranean Sea

Abstract Coastal ecosystems of the Mediterranean Sea are among the richest in non‐indigenous species, mostly due to the establishment of species coming from the Red Sea through the Suez Canal. Two herbivorous rabbitfishes, Siganus rivulatus and Siganus luridus, are already invasive in the south‐eastern part of the Mediterranean Sea where they cause ecological damage by overgrazing algae. The early detection and the counting of these non‐indigenous species in the rest of the Mediterranean Sea is thus a major challenge for scientists and ecosystem managers. However, analysing images from divers or remote cameras is a demanding task. Here, a dataset of 31,285 images of Siganus spp. and of six common native fishes to the Mediterranean Sea was built from 40 underwater videos recorded at three reef habitats. A deep learning algorithm was then trained to identify Siganus spp. on images containing the eight Mediterranean species. Finally, the algorithm and a post‐processing filtering were tested with an independent dataset of 2024 images. The model had a recall of 0.92 for the Siganus genus (i.e., two Siganus species combined). After a confidence‐based post‐processing, the recall increased to 0.98 with only 4 out of 272 images of Siganus spp. being misclassified. Accuracy reached a score of 0.61 meaning that experts would have to discard false positives. Images of five native species not present in the training dataset yielded similar false positive rates than species present in the training dataset. Overall, the automatic processing of images by the model and then the checking of putative Siganus images by experts required up to five times less effort than a full processing by experts. The algorithm can help to efficiently detect these two invasive fishes in underwater images to evaluate progress towards conservation objectives and accelerate citizen‐based monitoring of coastal ecosystems.

Управление инфраструктурным обеспечением развития арктических территорий

The article considers global and regional levels of management of infrastructure support for the development of Arctic territories. It reveals the most pressing issues of joint exploitation of the Arctic territories in the interests of the Arctic Council countries. The Arctic Council, as a representative body at the international level of economic relations, acts as a management entity declaring the boundaries and priorities of the use of resources, opportunities and immediate territories of the Arctic zones. The presented article reflects the main priorities of the development of the Arctic regions at the international level. The priorities of management and individual management functions in the development of business relations in the Arctic Zone are determined. The article systematizes a number of scientific and practical tasks, the solution of which is necessary for the development of transport channels, but somehow affects the conservation of marine ecosystems of the Arctic seas. Priorities have been set in the use of marine resources, based on the systematization of international proposals for the joint use of Arctic territories. The method of induction is used to classify the subjects of management in the study. Management entities at the international level have been grouped. The international priorities of cooperation research at the macroeconomic level have been determined. The key results of international cooperation of states in the Arctic are presented. Possible sectors of combining domestic and foreign interests in the development of Arctic territories are identified. The difficulties in the implementation of management of the Arctic regions on the territory of the Russian Federation are substantiated. The key differences between the Southern Sea and Northern Sea transport infrastructures serving the development of East–West relations are identified. Priorities in the use of the Northern Sea Route are identified. The prospects of integration of Russian economic activities into promising directions of international transport communication development in the Arctic territories are revealed.

Diverse foraging strategies of breeding Swinhoe's Storm-petrel in the productive marginal sea of the Northwest Pacific

Understanding the foraging behavior is essential for investigating seabird ecology and conservation, as well as monitoring the well-being of the marine environment. Breeding seabirds adopt diverse foraging strategies to maximize energy gains and cope with the intensified challenges of parenting and self-maintenance. Such trade-off may stem from the heterogeneity of food resources and the constraints of central place foraging. Nevertheless, abundant marine productivity could alleviate the energy limitation for seabirds, resulting in a consistent foraging approach. Here, we investigated the foraging strategy during the breeding season of a cryptic small-sized seabird, Swinhoe's Storm-petrel (Hydrobates monorhis), in the Yellow Sea, a productive marginal sea of the Northwest Pacific. Using GPS tracking, we evaluated habitat preference, quantified the foraging strategy, and tested if environmental conditions and individual traits influence foraging trips. We found that Swinhoe's Storm-petrels preferred nearshore areas with shallow water and engaged in primarily short foraging trips. Distinctive southeastward and southwestward strategies emerged when combining trip metrics, including foraging direction, duration, and maximum distance. The bathymetry, proximity to the coastline, and sea surface temperature differed in two foraging strategies. Foraging strategies exhibited flexibility between individuals, potentially explained by wing morphology, in which longer-winged birds are more likely to embark on longer-distance foraging trips. These findings highlight the impact of environmental factors and individual traits on seabirds' foraging decisions in productive marginal sea ecosystems. Our study also provides valuable insights into the foraging ecology of this Asian endemic storm-petrel.

Phylogeny and ultrastructure of Elthusa raynaudii (Isopoda, Cymothoidae) firstly recorded from the invasive silver cheeked toadfish (Lagocephalus sceleratus) (Gmelin 1789) in eastern Mediterranean Sea coast

With the opening of the Suez Canal in 1869, many changes have occurred in the Mediterranean Sea ecosystem so became a home to many invasive Lessepsian marine species that have migrated from the Red Sea. About 500 marine species including pufferfish have immigrated and rapidly established a population in the Mediterranean Sea causing significant impact on its ecosystem and fisheries sector. The parasitic fauna of these pufferfish has scarcely been studied in the Mediterranean Sea and also in their native habitat. During this surveillance study on the invasive pufferfish species from the Egyptian Mediterranean coast, the female cymothoid isopod Elthusa raynaudii was detected from the branchial cavity and also in the buccal cavity of 23.9% of the examined Lagocephalus sceleratus. The isolated isopod species was firstly identified and described through electron microscopy and molecular phylogeny based on the sequences of mitochondrial 16S rRNA gene. Additionally, the description of eggs, embryonic stage, and manca of E. raynaudii was firstly provided. The pathological impact on the infested fish tissues was investigated and revealed curling and loss of secondary gill lamellae in addition to mucous exudates in between the gill filaments and granuloma formation in the gill arch. The study provided the first report of L. sceleratus as a new host for the isopod E. raynaudii collected from the Egyptian Mediterranean coast as a new locality record. The role of the Lessepsian invasive pufferfish in transmitting parasites to the native fish species was discussed.Graphical

Marine litter and plastic detection on Black Sea beaches by using unmanned aerial vehicle (UAV)

Abstract Plastic and marine litter is one of the current growing issues worldwide, affecting the unique Black Sea ecosystem as well. Litter is yearly monitored for assessing ecological status across the Romanian beaches. We tested aerial drone-inspection or UAV method versus visual census for efficiency of litter monitoring on two Black Sea beaches, located in the Danube Delta area. The detection probability varied between size-category of items, with 71 – 100% accuracy of visual screening of drone images. Our pilot study showed the successful combination of the traditional visual census method with the new emerging UAV techniques for marine litter monitoring in the selected areas. To the best of our knowledge, this is the first study evaluating the UAV method for fast-screening of not-easily accessible sites at the Romanian coast of the Black Sea.

European research project on the state of pollution in the Black Sea «Black Sea SIERRA»: mission and partic ipation of Ukrainian oceanographers

The destruction of civil and industrial objects in Ukraine caused by a decade-long armed conflict, especially since February 2022, has led to extensive environmental pollution within the country, particularly in the waterways of the Black Sea basin.
 The consequences of these actions have also affected the state of the Black Sea, causing concern for the European Union and the global scientific community. Therefore, within the framework of the European program «Horizon Europe», funds were allocated for scientific research into the consequences of pollution in coastal water bodies and the Black Sea as a whole. In the 2023 «Horizon Europe» project competition, a proposal by an intergovernmental consortium of 7 scientific organizations from 5 countries was awarded the grant, including the State Institution «Scientific Hydrophysical Center of the National Academy of Sciences of Ukraine».
 The project aims to create effective monitoring and quality control strategies for water, as well as the implementation of innovative technologies to reduce the impact of pollutants on the ecosystems of the Black Sea. The application of research results is planned for the development of environmentally sound recommendations and strategies for the conservation of the marine environment. The project involves collaboration between countries to address pollution issues and study the Black Sea, as well as the development of scientific approaches to water resource management in the region. Special attention is given to the development of educational programs regarding the impact of military pollution on the water ecosystems of the Black Sea region.
 This article describes the localization, factors, and types of pollution in waterways and the Black Sea basin, the project’s structure, types of activities, and the investigated water bodies in Ukraine, as well as the participation of SI «Scientific Hydrophysical Center of NAS of Ukraine» as a project participant.

Assessment of the Impact of Pacific Inflow on Sea Surface Temperature Prior to the Freeze-Up Period over the Bering Sea

Warm water inflow from the Northeast Pacific has always been considered a crucial factor in early winter freeze-up in the Bering Sea. There is a strong correlation between changes in sea surface temperature (SST) on the eastern Bering Sea shelf and sea ice area in December. However, there is still limited research on the impact of Pacific inflow on SST on the eastern Bering Sea shelf, resulting in insufficient measurements of the impact of Pacific inflow on early freeze-up. In this article, the definition of marine heatwaves (MHW) is used to extract warm events (with a threshold of the 70th percentile) and cold events (with a threshold of the 30th percentile) from the eastern Bering Sea shelf in November. Self-organizing map (SOM) technology is utilized to classify extracted cold and warm events and the mixed-layer heat budget is ultimately used to explore the factors that generate and maintain these cold and warm events. Between 1993 and 2021, a total of 12 warm and 12 cold events are extracted and their cumulative intensity is found to be strongly correlated with the interannual variation in SST by 99.8%, indicating that these warm and cold events are capable of characterizing the interannual variation in SST. Among the 12 warm events, 9 of them can be attributed to abnormal warming of seawater before November and only 3 events are attributed to warm water inflow from the Northeast Pacific. During the development of warm events, there are only two events in which the warm inflow from the Northeast Pacific has a more profound regulatory effect on warm events in November. Moreover, both generation and regulatory factors of cold events are the net air–sea heat flux. Statistics indicate that the warm water inflow from the Northeast Pacific has a limited effect on SST on the eastern Bering Sea shelf during the early freeze-up period. Changes in local SST are more influenced by the residual heat before November and by local net air–sea heat flux. However, we highlight that long-term ocean heatwaves occurring in the Northeast Pacific can enlarge the residual heat of seawater in the eastern Bering Sea shelf before November, thereby impacting early freeze-up. The frequency of such events has significantly increased in the past decade, causing notable changes in the climate and ecosystem of the Bering Sea. Therefore, it is crucial to continue closely monitoring the occurrence and development of such events in the future.

Endocrine patterns associated with ovarian development in female Pacific halibut (Hippoglossus stenolepis)

The Pacific halibut (Hippoglossus stenolepis) is a large migratory demersal flatfish species that occupies a top trophic role in the North Pacific Ocean and Bering Sea ecosystems, where it also supports various fisheries. As a first attempt to characterize the endocrine mechanisms driving sexual maturation in this important species, we collected pituitary, ovarian and blood samples from Pacific halibut females captured in the wild that were classified histologically into various female developmental stages. We conducted gene expression analyses of gonadotropin beta subunits in the pituitary and observed that mRNA expression levels of fshb gradually increased throughout vitellogenesis, remained elevated until before ovulation and declined after spawning. In contrast, the mRNA expression levels of lhb markedly increased during oocyte maturation and remained elevated until after spawning. Ovarian mRNA expression levels of the gonadotropin receptor genes fshr and lhr peaked during oocyte maturation and before spawning, respectively, immediately following the developmental stage at which pituitary fshb and lhb mRNA expression first reached maximum levels. The ovarian gene expression patterns of steroidogenic enzyme genes cyp19a1 and hsd20b2 paralleled those of fshr and lhr, respectively. Testosterone and 17β-estradiol (E2) plasma levels increased concomitantly with fshr and cyp19a1 mRNA expression levels, and vitellogenin plasma levels increased throughout vitellogenesis and reached maximum levels prior to spawning. These results are consistent with the notion that in female Pacific halibut, as in other teleosts, vitellogenesis and oocyte maturation and ovulation are likely under the control of pituitary gonadotropic hormones Fsh and Lh, respectively.

Summer monsoon promotes the energy transfer efficiency of the zooplankton community in northern South China sea

The summer monsoon shows a fundamental influence on the pelagic ecosystem of the South China Sea. Zooplankton are a major link for energy transfer between primary producers and upper trophic levels. Therefore, evaluating the energy transfer efficiency (ETE) of zooplankton is crucial to understand the function of pelagic ecosystem under the influence of monsoon. In this study, field surveys were conducted during May (intermonsoon) and August 2021 (summer monsoon) focusing on the variation of zooplankton size and trophic structures across the shelf and slope. The result showed that the summer monsoon reinforced the gradient of abundance, biovolume, and biomass from slope to shelf, and greatly intensified the role of environmental factors in driving spatial variation in most taxa. Both the results of size and trophic structures indicated that the ETE of zooplankton decreased from slope to shelf. The size structure also indicated that the ETE of zooplankton significantly increased under the influence of summer monsoon. These results were consistent with previous studies by different methods, suggesting that these approaches of size and trophic structures had important potential value in assessing changes in the function of marine pelagic ecosystem, especially when compared with sufficient historical data or reanalyzing historical samples.

The role of community-based tourism for mangroves conservation in Banten, Indonesia

Mangroves provide multiple ecological functions such as connectors and balancers of land and sea ecosystems. The presence of mangroves in coastal areas is very important for reducing the impact of tsunamis and tidal flooding. The role of local communities in the form of community-based tourism models, in conserving mangrove forests has not been extensively studied. This study aims to fill the gap in evaluating local communities’ involvement, particularly under the tourism-based communities’ model, in conserving mangroves and, at the same time, gaining economic benefits. This study was conducted in the mangrove villages of “Patikang,” Citeureup Village, and Pandeglang Regency. This study applied mixed methods that combine both quantitative and qualitative approaches. Primary data were obtained directly from the local community through using questionnaires, interviews, and field observations. Secondary data collection was carried out through a literature review of mangrove conservation and community development in coastal areas. Our study found that local community-based tourism namely “Putri Gundul” played a very important role in increasing community awareness to conserve mangrove forests. The community has gained more knowledge on the biology of mangrove species and the ecology of mangroves for mangrove restoration. Furthermore, the involvement of local communities in mangrove conservation and restoration can increase the economy of communities by producing various products from mangroves.

Effects of anthropogenic and environmental stressors on the current status of red mullet (Mullus barbatus L., 1758) populations inhabiting the Bulgarian Black Sea waters

The red mullet (Mullus barbatus Linnaeus, 1758) is a keynote species for the Bulgarian Black Sea ecosystem and fisheries; nevertheless, existing knowledge on population status is very scarce. The present study was intended to assess the health status and adaptive potential of M. barbatus populations inhabiting the Bulgarian waters of the Black Sea. Our findings revealed that populations of M. barbatus are exposed to a variety of anthropogenic and environmental stressors. The species’ status was assessed using representative genetic, morphological, biochemical and chemical biomarkers from specimens obtained in the research area’s northern and southern regions. Based on mtDNA markers, genetic analysis revealed low haplotype and nucleotide diversity, typically observed in overexploited or “threatened” populations. Examining the morphology of the specimens revealed no discernible pattern of differentiation. Except for aluminium and chrome, metal and PAH concentrations in fish were below the regulatory thresholds. The specimens from the southern region ingested more microplastics than those from the northern region. The majority of specimens collected from the southern region also exhibited elevated levels of oxidative stress and decreased antioxidant defence, which can be interpreted as an early indication that they had reached the limits of their adaptive potential. Further research on the composite effects of the stressogenic environment on the Black Sea biota are critically needed, as well as the introduction of new indicators and thresholds at molecular and cellular levels for adequate monitoring of both the ecological state of the marine environment and its biota.

Sunscreens and micro(nano)plastics: Are we aware of these threats to the Egyptian coral reefs?

During a snorkeling trip to Marsa Alam and Hamata (southern Red Sea Riviera, Egypt) I explored the coral reefs and the diverse marine habitats of fish and invertebrate species. The area invites recreational diving and snorkeling, but the beaches are littered with all sorts of solid waste (mainly fragmented plastics). Also, there are no local restrictions on sunscreen use. The development of tourism to the area raises questions about the environmental impact and how its further growth will have on coral reefs. Every year, 1.2 million tourists visit the Red Sea coast (about 3287 tourists per day) and release about 1.7 tons/month of sunscreen into the Red Sea. As an ecologist and editorial board member of Science of the Total Environment, I ask myself how we as scientists can increase public awareness and call for prompt actions to protect the coral reefs. The discussion underlines two major threats to the Egyptian coral reefs: sunscreen use and micro(nano)plastics waste. The discussion closes with possible solutions, future perspectives, and recommendations to protect the coral reefs ecosystem of the Egyptian Red Sea.

Manifestation of internal waves in the Southern Caspian Sea using satellite imagery

Iran's South Caspian coast is an important agricultural hotspot and densely populated area that attracts about 20 million domestic tourists in summer. Therefore, not only the coastal area ecosystem of the South Caspian Sea (SCS) but also their marine ecosystem is exposed to different environmental pollution. The ecosystem of the SCS especially in the onshore area strongly affected by Internal Waves (IWs) dynamics. IWs can capture, concentrate and transport, floating plastic debris, larvae, contaminants, and toxic pollutants in this basin. Therefore, detecting and zoning the SCS for IWs is critical to the management and protection of this enclosed basin. Measured data obtained from CTD and satellite imagery archives from Landsat 7, 8, and Sentinel-2 have been used to analyze and manifest IWs. Analysis and comparison of different satellite images reveal that the maximum wavelength of the IWs packet was about 400 m with a crest length of 18,000 m. However, the minimum packet had a wavelength of about 20 m with a crest length of 360 m. Based on the occurrence of IWs extracted by edge-finding algorithms on satellite images, the SCS can be divided into six original zones. Four zones of them located near the coastal line where freshwater rivers discharge to the sea in the rainy season and two other zones are in the deep water, which form under the dominant sea surface wind regime and sharp changing of bathymetry.