Changes In Marine Environment Research Articles

Organellar genome comparisons of Sargassum polycystum and S. plagiophyllum (Fucales, Phaeophyceae) with other Sargassum species

BackgroundSargassum polycystum C. Agardh and Sargassum plagiophyllum C. Agardh are inhabitants of tropical coastal areas, their populations are negatively influenced by global warming and marine environment changes. The mitochondrial and chloroplast genomes of these species have not been sequenced.ResultsThe mitochondrial genomes of S. polycystum and S. plagiophyllum were 34,825 bp and 34,862 bp, respectively, and their corresponding chloroplast genomes were 124,493 bp and 124,536 bp, respectively. The mitochondrial and chloroplast genomes of these species share conserved synteny, sequence regions and gene number when compared with the organellar genomes of other Sargassum species. Based on sequence analysis of 35 protein-coding genes, we deduced that S. polycystum and S. plagiophyllum were closely related with S. ilicifolium; these species diverged approximately 0.3 million years ago (Ma; 0.1–0.53 Ma) during the Pleistocene period (0.01–2.59 Ma). Rates of synonymous and non-synonymous substitutions in the mitochondrial genome of the Sargassum genus were 3 times higher than those in the chloroplast genome. In the mitochondrial genome, rpl5, rpl31 and rps11 had the highest synonymous substitution rates. In the chloroplast genome, psaE, rpl14 and rpl27 had the highest synonymous substitution rates.ConclusionsPhylogenetic analysis confirms the close relationship between the two sequenced species and S. ilicifolium. Both synonymous and non-synonymous substitution rates show significant divergence between the group of mitochondrial genomes versus the group of chloroplast genomes. The deciphering of complete mitochondrial and chloroplast genomes is significant as it advances our understanding of the evolutionary and phylogenetic relationships between species of brown seaweeds.

The effects of low pH and high water temperature on oxidative stress and cell damage in juvenile olive flounder Paralichthys olivaceus: comparison of single and combined environmental conditions.

The use of fossil fuels by anthropogenic activities causes ocean acidification and warming, and these changes in the marine environment can negatively affect the metabolism, growth, and survival of fish. In the present study, we evaluated the ability of olive flounder Paralichthys olivaceus to cope with future marine environmental changes by investigating the oxidative stress (cortisol, HSP70), antioxidant enzyme (superoxide dismutase; SOD, catalase; CAT) activity, and apoptosis (caspase-3) after exposure to control conditions (20°C and pH 8.1), warming (30°C) and acidification (pH 7.5) conditions, and a combined environment (30°C and pH 7.5) for 28days. Under warming conditions, increased oxidative stress, activity of antioxidant enzymes, and apoptosis were observed. Acidifying conditions showed negative effects at the beginning of exposure, but these effects were offset over time. Even in a combined environment of acidification and warming, negative effects were seen only at the beginning of exposure and were not sustained. In conclusion, the effects of acidification on oxidative stress, antioxidant response, and apoptosis in P. olivaceus did not exceed the effects of warming. These results suggest that P. olivaceus can cope with the predicted future acidifying environment.

Hybrid model navigation method for autonomous underwater vehicle

Accurate navigation and localization are essential for Autonomous Underwater Vehicles (AUVs). However, the unknown modeling errors and nonlinear errors will affect the AUV positioning accuracy. Meanwhile, the marine environment changes may not be accurately sensed by AUV. Therefore, this paper proposes a Hybrid Model (HM) navigation methodology for AUV to reduce the impact of unknown errors and better predict the future states simultaneously. Firstly, an error correction sub-model based on Sequence to Sequence (Seq2Seq) predicts AUV pseudo displacements. The pseudo displacements are augmented to the observation vector to correct the unknown errors in the state estimation. Secondly, a state regression sub-model based on Gaussian Process Regression (GPR) is utilized to capture the motion trends from the historical data and regress the state variation, which is used to resist the unknown disturbances in the changeable marine environment. The sub-models work parallel with the master model, benefiting from the Interacting Multiple Model (IMM). We compare the performance of the proposed HM to Extended Kalman Filter (EKF), Unscented Kalman Filter (UKF), and IMM-EKF by using the actual experimental data of Sailfish 210 AUV. The experimental results show that the proposed HM algorithm achieves superior navigation accuracy and good fault tolerance capability.

Pattern evolution and impact factor of Jiuduansha Wetland at the Yangtze Estuary during 1989-2020

Affected by the changes of drainage basin and marine environment and human activities, estuarine wetland is fragile, sensitive, and complex in evolution. Jiuduansha Wetland is the largest estuarine shoal wetland in the Yangtze Estuary, and is undergoing rapid changes due to the reduction of sediment inputs and the invasion of alien species Spartina alterniflora. In this study, the changes of Jiuduansha Wetland from 1989 to 2020 were analyzed through remote sensing interpretation, field investigation, and topographic data analysis. The impacts of watershed sediment reduction and S. alterniflora invasion on Jiuduansha Wetland were analyzed based on the hydrological data of Datong station and the invasion history of S. alterniflora. The results showed that the total area of Jiuduansha Wetland (above -5 m) first increased and then decreased since 1991, reaching its maximum in 2005 (421.16 km2). The area of tidal flat wetland (above 0 m) and wetland vegetation increased continuously from 1989 to 2020, with 1.5 times and 47.1 times increases, respectively. The decreases of sediment supply led to a decrease in the total area of Jiuduansha Wetland (above -5 m) and a decrease growth rate of tidal flat wetland area above 0 m and vege-tation area. The invasive species S. alterniflora had expanded rapidly, occupied the space of native species, and became the dominant species in Jiuduansha Wetland since it was introduced in 1997. Sediment reduction and S. alterniflora invasion had led to the rapid changes of Jiuduansha Wetland structure. In order to avoid the degradation of ecological service, wetland protection and restoration should be taken to maintain the stability and health of Jiu-duansha Wetland.

Stratigraphic and chronological characteristics of Shidao Island within the Xisha Islands, South China Sea, and its response to sea‐level changes since the Late Pleistocene

Sedimentological and chronological analyses of coastal dunes can determine their sedimentation processes and yield information that can reflect changes in local marine environments (e.g., information on climate, biology, and sea‐level changes in tectonically stable areas). In this study, Late Quaternary deposits on Shidao Island, one of the Xisha Islands, South China Sea, were analysed using techniques such as U/Th dating to obtain the following results: (1) Four lithofacies associations and two unconformities were identified from the deposits on Shidao Island. On this basis, the Shidao Island sediments can be divided into three stages of aeolian sediments and one stage of beach rock sediments. (2) U/Th dating revealed that the aeolian deposits on Shidao Island formed during three periods, namely, marine isotope stages 5.2, 5.1, and 4, and that the beachrocks were formed in the Holocene when the sea level rose to its present height. (3) The aeolianites on Shidao Island all formed in an environment in which the sea level was relatively stable or slowly falling. This study determined for the first time the specific sedimentary ages of the aeolianites on Shidao Island, and reconstructed the sedimentation process of the deposits on Shidao Island based on palaeo‐sea‐level changes. These results can provide more reliable geochronology data for the future study of Late Quaternary marine environments across the East Asian region.

Large-scale changes in marine and terrestrial environments drive the population dynamics of long-tailed ducks breeding in Siberia

Migratory animals experience very different environmental conditions at different times of the year, i.e., at the breeding grounds, during migration, and in winter. The long-tailed duck Clangula hyemalis breeds in the Arctic regions of the northern hemisphere and migrates to temperate climate zones, where it winters in marine environments. The breeding success of the long-tailed duck is affected by the abundances of predators and their main prey species, lemmings Lemmus sibiricus and Dicrostonyx torquatus, whose population fluctuation is subject to climate change. In the winter quarters, long-tailed ducks mainly eat the blue mussel Mytilus edulis. We examined how North-west Siberian lemming dynamics, assumed as a proxy for predation pressure, affect long-tailed duck breeding success and how nutrient availability in the Baltic Sea influences long-tailed duck population size via mussel biomass and quality. Evidence suggests that the long-tailed duck population dynamics was predator-driven on the breeding grounds and resource-driven on the wintering grounds. Nutrients from fertilizer runoff from farmland stimulate mussel stocks and quality, supporting high long-tailed duck population sizes. The applied hierarchical analysis combining several trophic levels can be used for evaluating large-scale environmental factors that affect the population dynamics and abundance of migrants from one environment to another.

A Dramatic Marine Environment Change in the Beibu Gulf of the South China Sea around 3.2 kyr BP

Abstract The profile geochemical characteristics of a seafloor sediment core, collected from the Beibu Gulf of the South China Sea, have been investigated in terms of the sediment grain size, the content of major and trace elements, the total organic carbon (TOC) and organic nitrogen (TN), and the carbon isotopic composition of organic matter (δ13Corg) and AMS 14C dating. These results show that the core sediments were deposited since 11.3 kyr BP and the profile could be clearly divided into the lower and upper sediment section based on geochemical characteristics. The lower section covers the depth of 86 cm to 200 cm and was deposited from 3.2 to 11.3 kyr BP, while the upper section is at the depth of 4 to 86 cm and represents sediments from 0.2 to 3.2 kyr BP. The upper section sediments are charcteristized by a much finer grain size and a clearly positive deviation of the δ13Corg value. Obviously, the overall profile geochemical characteristics indicate that the upper section was deposited under a significantly deeper seawater depth associated with a relatively weaker hydrodynamic and a better preservation condition for organic matter, while the low section was deposited under a relatively shallow seawater depth with the relatively stronger hydrodynamic condition and a relatively poor preservation condition for organic matter. Finally, it is suggested that the transition between the lower section and the upper section occurring around 3.2 kyr BP was mostly likely due to a dramatic marine environmental change caused by the rapid seafloor subsidence associated with the further expansion of the Qiongzhou Strait. And further multidisciplinary studies are needed to better reveal and understand different aspects of the significance of this marine environment change in the Beibu Gulf of the South China Sea.

A framework for mapping and monitoring human-ocean interactions in near real-time during COVID-19 and beyond

The human response to the COVID-19 pandemic set in motion an unprecedented shift in human activity with unknown long-term effects. The impacts in marine systems are expected to be highly dynamic at local and global scales. However, in comparison to terrestrial ecosystems, we are not well-prepared to document these changes in marine and coastal environments. The problems are two-fold: 1) manual and siloed data collection and processing, and 2) reliance on marine professionals for observation and analysis. These problems are relevant beyond the pandemic and are a barrier to understanding rapidly evolving blue economies, the impacts of climate change, and the many other changes our modern-day oceans are undergoing. The “Our Ocean in COVID-19″ project, which aims to track human-ocean interactions throughout the pandemic, uses the new eOceans platform (eOceans.app) to overcome these barriers. Working at local scales, a global network of ocean scientists and citizen scientists are collaborating to monitor the ocean in near real-time. The purpose of this paper is to bring this project to the attention of the marine conservation community, researchers, and the public wanting to track changes in their area. As our team continues to grow, this project will provide important baselines and temporal patterns for ocean conservation, policy, and innovation as society transitions towards a new normal. It may also provide a proof-of-concept for real-time, collaborative ocean monitoring that breaks down silos between academia, government, and at-sea stakeholders to create a stronger and more democratic blue economy with communities more resilient to ocean and global change.

Changes in phytoplankton size structure in the East Sea 2018-2020 due to marine environment change

Changes in phytoplankton size structure in the East Sea 2018-2020 due to marine environment change

Marine Environmental Change Induced by Anthropogenic Activities – From a Viewpoint of Aquatic Palynomorph Assemblages Preserved in Sediment Cores of Beppu Bay, West Japan

Stratigraphic cluster analysis using aquatic palynomorphs preserved in the core sediments revealed a rapid eutrophication due to anthropogenic activities from the mid 1960s in Beppu Bay, East Kyushu, Japan. These assemblages were divided into three major units: BP-I, BP-II and BP-III, and also only dinoflagellate cyst assemblages were divided into the following four units in Beppu Bay: BP-A, BP-B, BP-C, and BP-D. Unit boundaries based on aquatic palynomorphs and dinoflagellate cysts were different except in the upper part, BP-III and BP-D, both of which clearly indicated anthropogenic eutrophication in both sea water and bottom sediments. On the other hand, in dinoflagellate cyst assemblages, Unit BP-A was characterized by stable occurrence of Spiniferites bulloideus and Spiniferites hyperacanthus, Lingulodinium machaerophorum of Gonyaulacales, and reduction of heterotrophic Peridinioid Brigantedinium spp. In Unit BP-C there was a clear decrease of L. machaerophorum. Unit BP-B was characterized by decreases of S. bulloideus, S. hyperacanthus, and L. machaerophorum, and little increase of Spniferites bentori. Unit BP-C was characterized by an increase in S. bulloideus and heterotrophic Peridinioid Echinidinium spp. Unit BP-D was subdivided into Subunit BP-D1 where dinoflagellate cysts showed a marked increase in S. bulloideus accompanied by the appearance of L. machaerophorum and Tuberculodinium vancampoae, and Subunit PB-D2 where there was a decrease of total dinoflagellate cysts. From the dinoflagellate cyst assemblages, the marine environment of the period of BP-A Unit was suggested to be warm and stable. However, L. machaerophorum started to decrease in BP-B. The clear decrease of L. machaerophorum suggest that the marine environment became cooler than that of Unit BP-A. Significant increases of S. bulloideus, S. hypearcanthus, L. machaerophorum, T. vancampoae, Brigantedinium spp., and Polykrikos kofoidii were characteristic of Unit BP-D. The increase in total dinoflagellate cyst density and the increase of the ratio of heterotrophic dinoflagellate cysts in Subunit BP-D1 are manifestations of the Oslo fjord Signal and Heterotroph Signal, respectively. In addition, the decrease in microforaminiferal lining that continued from Unit BP-C to Unit BP-D might indicate deterioration of the bottom sediment environment.

Geochemical characteristics and paleoclimate implication of Middle Jurassic coal in the Ordos Basin, China

Coals are highly enriched in critical elements (rare earth elements, etc.), containing much information of paleoenvironmental and paleoclimatic during deposition. The Jurassic period is a significant coal-forming period in the world. The Yan’an Formation in the Ordos Basin in north China is among the largest Middle Jurassic coal fields of the world. The purpose of this study is to investigate the geochemical characteristics of Middle Jurassic Aalenian coals of Ordos Basin and their paleoclimate significance. Sixty-two coal samples were collected from two coal mines in the Dongsheng area in the northeast Ordos Basin. The major and trace elements in the coal samples were analyzed using X-ray fluorescence (XRF) and inductively coupled plasma-mass spectrometry (ICP-MS). The main oxides in the Yan’an coals are SiO2 and CaO. In comparison with average values for China, the coals from the Ordos Basin have a slight enrichment of CaO and MgO. Strontium and Mo values are also slightly enriched. Yttrium and rare earth elements are depleted in the coals, with a range of 8–269 μg/g (average = 48.5 μg/g; on an ash basis). The coals in the Yan’an Formation have a negative Eu anomaly, suggesting that the peat bog had a stable terrigenous material supply during the coal-forming period. The continental saline water system and oxygen-suboxygenic environment were inferred from the Sr/Ba, U/Th, Ni/Co, Sr/Cu. The Sr/Cu and Sr/Ba data of Yan’an Formation coal seams in the Ordos Basin also indicate climate change from a relatively arid condition to a more humid climate, which is consistent with change of marine environment during the Aalenian. Global cooling during the Aalenian may have triggered strengthened moisture transport by westerlies in mid-latitude inland Asia, and therefore a humid climate in the Ordos Basin.

Effects of Miniaturization of the Summer Phytoplankton Community on the Marine Ecosystem in the Northern East China Sea

After the construction of the Three Gorges Dam (Changjiang River), the northern East China Sea has been exposed to major environmental changes in the summer due to climate change and freshwater control. However, little is known regarding phytoplankton in this area. Here, we investigated differences in the summer phytoplankton-community structure as a consequence of marine-environment changes from 2016 to 2020. In the 2000s, the key dominant species in the summer phytoplankton community in the northern East China Sea were diatoms and dinoflagellates. In this study, however, nanoflagellates of ≤20 µm were identified as the dominant species throughout the survey period, with abundances ranging from 43.1 to 69.7%. This change in the phytoplankton-community structure may be ascribed to low nutrient concentrations in the area, especially phosphate, which was below the detection limit, seriously hampering phytoplankton growth. The relative contribution of picophytoplankton to the total chlorophyll a biomass was highest in the surface mixed layer with low nutrient concentrations. Spatially, higher percentages were observed along the east-side stations than the west-side stations, where nutrient concentrations were relatively high. Conclusively, decreased nutrients led to phytoplankton miniaturization. Accordingly, as the dominance of picophytoplankton increases, energy transfer is expected to decrease at the upper trophic level.

Western Gull Foraging Behavior as an Ecosystem State Indicator in Coastal California

With accelerating climate variability and change, novel approaches are needed to warn managers of changing ecosystem state and to identify appropriate management actions. One strategy is using indicator species—like seabirds as ecosystem sentinels—to monitor changes in marine environments. Here, we explore the utility of western gulls (Larus occidentalis) breeding on Southeast Farallon Island as a proxy of ecosystem state in coastal California by investigating the interannual variability in gull foraging behavior from 2013 to 2019 in relation to upwelling conditions, prey abundances, and overlap with humpback whales (Megaptera novaeangliae) as gulls frequently feed in association with whales. Western gulls have a flexible diet and forage on land and at-sea. We combined gull GPS tracking data during the incubation phase, ecosystem survey data on multiple predator and prey species, and derived oceanographic upwelling products. When foraging at sea, gulls overlapped with cool upwelled waters. During 2015–2017, 25% more gull foraging trips visited land than in other years, where land trips were on average ∼8 h longer and 40% further than sea trips, which coincided with high compression of coastally upwelled waters (habitat compression) in 2015–2016. Gull foraging behavior was related to local prey abundances, where more foraging occurred near shore or on land when prey abundances were low. However, visual surveys indicated that ∼70% of humpback whale observations co-occurred with gulls, and the year with the most foraging on land (2017) corresponded to regionally low relative whale abundances, suggesting gull movement patterns could be an indicator of whale presence. Further, both whales and gulls forage near-shore under high upwelling habitat compression and low krill abundance. Hence, the deployment of year-round tags on gulls with the capability of near real-time data accessibility could provide important fine-scale metrics for conservation and management of the threatened yet recovering eastern Pacific humpback whale population between infrequent and coarse surveys. Entanglement in fishing gear and ship strikes are major inhibitors to whale recovery and have increased concomitantly with human use of ocean resources. Moreover, as climate variability and change increase, novel indicators should be explored and implemented to inform marine spatial planning and protect species across multiple scales from new risks.

Two cetacean species reveal different long-term trends for toxic trace elements in European Atlantic French waters

Cetaceans have been naturally exposed to toxic trace elements (TEs) on an evolutionary time scale. Hence, they have developed mechanisms to control and/or mitigate their toxic effects. These long-lived species located at high trophic positions and bioaccumulating toxic elements are assumed to be good biomonitoring organisms. However, anthropogenic emissions have strongly increased environmental levels of toxic TEs in the last decades, questioning the efficiency of the detoxication mechanisms in cetaceans. In this context, temporal trends of mercury (Hg), cadmium (Cd) and lead (Pb) concentrations were studied through the analysis of 264 individuals from two cetacean species the common dolphin (Delphinus delphis) and the harbour porpoise (Phocoena phocoena) and belonging to two different Management Units (MUs) for the latter. These individuals stranded along the French Atlantic coasts from 2000s to 2017. All the trends presented were age- and sex-corrected and stable isotope ratios of carbon (δ13C) and nitrogen (δ15N) were measured as proxies of their feeding ecology. Results showed that Pb concentrations clearly decreased over time in both species and MUs. This decrease agrees with the lead petrol regulation after 2000s, supporting the use of these species as valuable bioindicators of changes for TE levels in the marine environment. A significant long-term increase of total Hg concentrations was only observed in common dolphins. Cadmium concentrations also revealed different trends over the period in both species. The different Hg and Cd trends observed in the two species, probably reflected a contrasted contamination of habitat and prey species than a global increase of the contamination in the environment. These results highlight the necessity and gain of using different species to monitor changes in marine environments, each of them informing on the contamination of its own ecological niche. Lastly, the Se:Hg molar ratios of species suggested a low risk for Hg toxicity over time.

Monitoring Alaskan Arctic Shelf Ecosystems Through Collaborative Observation Networks

Ongoing scientific programs that monitor marine environmental and ecological systems and changes comprise an informal but collaborative, information-rich, and spatially extensive network for the Alaskan Arctic continental shelves. Such programs reflect contributions and priorities of regional, national, and international funding agencies, as well as private donors and communities. These science programs are operated by a variety of local, regional, state, and national agencies, and academic, Tribal, for-profit, and nongovernmental nonprofit entities. Efforts include research ship and autonomous vehicle surveys, year-long mooring deployments, and observations from coastal communities. Inter-program coordination allows cost-effective leveraging of field logistics and collected data into value-added information that fosters new insights unattainable by any single program operating alone. Coordination occurs at many levels, from discussions at marine mammal co-management meetings and interagency meetings to scientific symposia and data workshops. Together, the efforts represented by this collection of loosely linked long-term monitoring programs enable a biologically focused scientific foundation for understanding ecosystem responses to warming water temperatures and declining Arctic sea ice. Here, we introduce a variety of currently active monitoring efforts in the Alaskan Arctic marine realm that exemplify the above attributes.

Ecosystem Services Research Trends: A Bibliometric Analysis from 2000–2020

The study of ecosystem services (ES) is becoming increasingly popular, as it plays an important role in human wellbeing, economic growth, and livelihoods. The primary goal of this research is to investigate the global trend in ES research using a rigorous systematic review of highly cited articles. The articles for this study were extracted from Science Citation Index Expanded (SCI-E), Emerging Sources Citation Index (ESCI), and Social Sciences Citation Index (SSCI) databases of Web of Science Core Collection (WoSCC) covering the period from 2000 to 2020. This study was limited to SCI-E, ESCI, and SSCI databases of the Web of Science. The term “ecosystem service/s” has been used as a research term to filter the study sample and eliminate other databases from the analysis. A citation level equal to or greater than 200 was used to further filtration of articles. This query could restrict to 128 articles that are highly cited in the selected period. Bibliometric analysis results show that, according to the author’s keywords, the “ecosystem service/s” keyword is highly connected to the “biodiversity”, “valuation”, “marine spatial planning”, and “conservation planning”. The U.S.A., Canada, China, France, and Australia are the leading countries in the cumulative number of highly cited articles and networks of co-authors. The U.S.A. is a strong contributor to ES research with China, Canada, and France. The most productive universities linked to the United States were the University of Minnesota, the University of California-Santa Barbara (UC Santa Barbara), and the Chinese Academy of Science. The most significant and compelling author is Halpern S Benjamin, who represents UC Santa Barbara. He has earned international recognition for a model he developed to analyze global data sets of anthropogenic drivers of ecological change in marine environments. The most accessed and studied fields in the ES are terrestrial, urban, and marine environments.

Microfacies evidence for the evolution of Miocene coral-reef environments in Cyprus

Cyprus is one of the few areas of the Mediterranean where lower and upper Miocene coral-reefs occur in close proximity and is thus well suited to investigate how environmental and geological changes affected the reefs and their associated shallow-marine facies. The prevailing environmental conditions of the lower Miocene Terra Member and of the upper Miocene Koronia Member are reconstructed here, using detailed microfacies comparisons of the skeletal, foraminiferal and calcareous algal assemblages. The lower Miocene reefs are characterised by a higher biodiversity of coralline algae, large benthic foraminifera and corals, and mainly developed in slightly deeper water (20–40 m, lower euphotic zone) than the upper Miocene reefs (< 15 m; upper euphotic zone). The reduced late Miocene biodiversity was probably caused by changes in the Mediterranean marine environment (e.g. increased seasonality), possibly in response to global cooling, increased latitudinal gradients and progressive isolation of the basin. The observed shift of the reef environment towards the upper euphotic zone could be explained as a response to late Miocene physical oceanographic setting, notably temperature changes, which could have made the upper euphotic zone more favourable for certain hermatypic corals. Similarities between the Miocene carbonate facies of Cyprus and the Eratosthenes Seamount directly to the south, and elsewhere in the Mediterranean region (e.g., Corsica; Italy; Spain), suggest that the environmental changes inferred for the Miocene of Cyprus operated on a Mediterranean or even wider scale. • The skeletal assemblages of Miocene neritic carbonates of Cyprus are analysed. • Lower Miocene coral-reefs are highly biodiverse and developed between 20 and 40 m of water depth. • Upper Miocene coral-reefs display a low biodiversity and developed <15 m of water-depth. • Biodiversity decreased in response to less favorable conditions in the late Miocene.

Copernicus Sea Level Space Observations: A Basis for Assessing Mitigation and Developing Adaptation Strategies to Sea Level Rise

It is essential to monitor accurately current sea level changes to better understand and project future sea level rise (SLR). This is the basis to support the design of adaptation strategies to climate change. Altimeter sea level products are operationally produced and distributed by the E.U. Copernicus services dedicated to the marine environment (CMEMS) and climate change (C3S). The present article is a review paper that intends to explain why and to which extent the sea level monitoring indicators derived from these products are appropriate to develop adaptation strategies to SLR. We first present the main key scientific questions and challenges related to SLR monitoring. The different processing steps of the altimeter production system are presented including those ensuring the quality and the stability of the sea level record (starting in 1993). Due to the numerous altimeter algorithms required for the production, it is complex to ensure both the retrieval of high-resolution mesoscale signals and the stability of the large-scale wavelengths. This has led to the operational production of two different sea level datasets whose specificities are characterized. We present the corresponding indicators: the global mean sea level (GMSL) evolution and the regional map of sea level trends, with their respective uncertainties. We discuss how these products and associated indicators support adaptation to SLR, and we illustrate with an example of downstream application. The remaining gaps are analyzed and recommendations for the future are provided.

Insights into drivers of population declines offer a ray of hope for migratory fishes in the temperate rainforest.

Effective conservation of migratory species depends on understanding how their populations are influenced by conditions across multiple ecosystems. In this issue, Wilson et al. link changes in freshwater and marine environments to declines of salmonid fishes in a river flowing from the coastal temperate rainforest of British Columbia. Quantifying the factors influencing these fish declines provides insight into policy actions that might aid recovery, such as changes in forest management.

Marine and freshwater regime changes impact a community of migratory Pacific salmonids in decline.

Marine and freshwater ecosystems are increasingly at risk of large and cascading changes from multiple human activities (termed “regime shifts”), which can impact population productivity, resilience, and ecosystem structure. Pacific salmon exhibit persistent and large fluctuations in their population dynamics driven by combinations of intrinsic (e.g., density dependence) and extrinsic factors (e.g., ecosystem changes, species interactions). In recent years, many Pacific salmon have declined due to regime shifts but clear understanding of the processes driving these changes remains elusive. Here, we unpacked the role of density dependence, ecosystem trends, and stochasticity on productivity regimes for a community of five anadromous Pacific salmonids (Steelhead, Coho Salmon, Pink Salmon, Dolly Varden, and Coastal Cutthroat Trout) across a rich 40‐year time‐series. We used a Bayesian multivariate state‐space model to examine whether productivity shifts had similarly occurred across the community and explored marine or freshwater changes associated with those shifts. Overall, we identified three productivity regimes: an early regime (1976–1990), a compensatory regime (1991–2009), and a declining regime (since 2010) where large declines were observed for Steelhead, Dolly Varden, and Cutthroat Trout, intermediate declines in Coho and no change in Pink Salmon. These regime changes were associated with multiple cumulative effects across the salmon life cycle. For example, increased seal densities and ocean competition were associated with lower adult marine survival in Steelhead. Watershed logging also intensified over the past 40 years and was associated with (all else equal) ≥97% declines in freshwater productivity for Steelhead, Cutthroat, and Coho. For Steelhead, marine and freshwater dynamics played approximately equal roles in explaining trends in total productivity. Collectively, these changing environments limited juvenile production and lowered future adult returns. These results reveal how changes in freshwater and marine environments can jointly shape population dynamics among ecological communities, like Pacific salmon, with cascading consequences to their resilience.