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This study investigates the biomass production and growth strategies of the relict seagrass Zostera marina, a species sensitive to high temperatures, within the Venice Lagoon (Italy). Monthly data collected from January to December 2019 and November 2020 to October 2021 in a single station in proximity of one lagoon port-entrance, along with seasonal data from 2018 and 2021 for the whole lagoon, were analyzed in conjunction with environmental parameters and macroalgal presence. The objective was to understand the impact of climate changes, particularly rising water temperatures, on the cover, standing crop and net primary production of Z. marina and the effect of the MoSE gate closures designed to protect Venice from high-water events. Despite expectations of a decline due to temperature increase and reduced water exchange, our findings reveal a notable adaptability of Z. marina, with increases in both cover and biomass. This resilience suggests that Z. marina can counteract environmental challenges, making this study relevant for broader ecological and conservation contexts beyond the Venice Lagoon. [ABSTRACT FROM AUTHOR]

An increase in water temperature is one of the main factors that can potentially modify biogeochemical dynamics in lowland rivers, such as the removal and recycling of nitrogen (N). This effect of climate change on N processing deserves attention, as it may have unexpected impacts on eutrophication in the coastal zones. Intact sediment cores were collected seasonally at the closing section of the Po River, the largest Italian river and one of the main N inputs to the Mediterranean Sea. Benthic oxygen fluxes, denitrification, and dissimilatory nitrate reduction to ammonium (DNRA) rates were measured using laboratory dark incubations. Different temperature treatments were set up for each season based on historical data and future predictions. Higher water temperatures enhanced sediment oxygen demand and the extent of hypoxic conditions in the benthic compartment, favoring anaerobic metabolism. Indeed, warming water temperature stimulated nitrate (NO3−) reduction processes, although NO3− and organic matter availability were found to be the main controlling factors shaping the rates between seasons. Denitrification was the main process responsible for NO3− removal, mainly supported by NO3− diffusion from the water column into the sediments, and much more important than N recycling via DNRA. The predicted increase in the water temperature of the Po River due to climate change may exert an unexpected negative feedback on eutrophication by strongly controlling denitrification and contributing to partial buffering of N export in the lagoons and coastal areas, especially in spring. [ABSTRACT FROM AUTHOR]

Supra‐permafrost submarine groundwater discharge (SGD) in the Arctic is potentially important for coastal biogeochemistry and will likely increase over the coming decades owing to climate change. Despite this, land‐to‐ocean material fluxes via SGD in Arctic environments have seldom been quantified. This study used radium (Ra) isotopes to quantify SGD fluxes to an Arctic coastal lagoon (Simpson Lagoon, Alaska) during five sampling periods between 2021 and 2023. Using a Ra mass balance model, we found that the SGD water flux was substantial and dependent on environmental conditions. No measurable SGD was detected during the spring sampling period (June 2022), when the lagoon was partially ice‐covered. During ice‐free periods, the main driver of SGD in this location is wind‐driven lagoon water level changes, not tides, which control surface water recirculation through sediments along the lagoon boundary. A combination of wind strength and direction led to low SGD fluxes in July 2022, with an SGD flux of (6 ± 3) × 106 m3 d−1, moderate fluxes in August 2021 and July 2023, which had an average flux of (17 ± 9) × 106 m3 d−1, and high fluxes in October 2022, at (79 ± 16) × 106 m3 d−1. This work demonstrates how soil and environmental conditions in the Arctic impact Ra mobilization, laying a foundation for future SGD studies in the Arctic and shedding light on the major processes driving Ra fluxes in this important environment. [ABSTRACT FROM AUTHOR]

Coastal lagoons are highly productive transitional water bodies threatened by human factors and vulnerable to global climate change effects. Monitoring biophysical parameters in these ecosystems is crucial for their preservation. In this work, we used Sentinel-2 and Landsat imagery combined with in situ data to (1) develop preliminary algorithms for retrieving the Chl-a concentration and water surface temperature of six lagoons located in the Ebro Delta (NE Mediterranean Sea, Spain), and to (2) compute maps and trend lines for analysing their spatiotemporal evolution from 2015 to 2022. Our findings showed that the algorithms' accuracy ranged from 72% to 78% and had limited potential under high Chl-a concentration regimes. Even so, they revealed the lagoons' trophic status, usual fluctuations, and deviations of both parameters attributed to seasonal (i.e., light and temperature) and short-term physical (i.e., winds) forcing, as well as valuable spatial patterns potentially useful for conservation efforts and land use planning. Future work will focus on the acquisition of a larger in situ data sample under a range of environmental conditions to improve the algorithms' robustness, which in turn will allow the investigation of natural and human factors controlling the dynamics of the two investigated parameters. [ABSTRACT FROM AUTHOR]

This study presents the environmental mapping of the Chilika Lake coastal lagoon, India, using satellite images Landsat 8-9 OLI/TIRS processed using machine learning (ML) methods. The largest brackish water coastal lagoon in Asia, Chilika Lake, is a wetland of international importance included in the Ramsar site due to its rich biodiversity, productivity, and precious habitat for migrating birds and rare species. The vulnerable ecosystems of the Chilika Lagoon are subject to climate effects (monsoon effects) and anthropogenic activities (overexploitation through fishing and pollution by microplastics). Such environmental pressure results in the eutrophication of the lake, coastal erosion, fluctuations in size, and changes in land cover types in the surrounding landscapes. The habitat monitoring of the coastal lagoons is complex and difficult to implement with conventional Geographic Information System (GIS) methods. In particular, landscape variability, patch fragmentation, and landscape dynamics play a crucial role in environmental dynamics along the eastern coasts of the Bay of Bengal, which is strongly affected by the Indian monsoon system, which controls the precipitation pattern and ecosystem structure. To improve methods of environmental monitoring of coastal areas, this study employs the methods of ML and Artificial Neural Networks (ANNs), which present a powerful tool for computer vision, image classification, and analysis of Earth Observation (EO) data. Multispectral satellite data were processed by several ML image classification methods, including Random Forest (RF), Support Vector Machine (SVM), and the ANN-based MultiLayer Perceptron (MLP) Classifier. The results are compared and discussed. The ANN-based approach outperformed the other methods in terms of accuracy and precision of mapping. Ten land cover classes around the Chilika coastal lagoon were identified via spatio-temporal variations in land cover types from 2019 until 2024. This study provides ML-based maps implemented using Geographic Resources Analysis Support System (GRASS) GIS image analysis software and aims to support ML-based mapping approach of environmental processes over the Chilika Lake coastal lagoon, India. [ABSTRACT FROM AUTHOR]

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Guanacache Lagoons is a system of wetlands, marshes and lagoons associated with the Desaguadero River in the Cuyo region, central-west Argentina. In the upper stretches of the basins of the main rivers that feed this lagoons system, there is a large consumption of water resources and a high degree of intervention through hydraulic infrastructure built for water management. This situation began at the end of the 19th century, with the consolidation of the National State and provincial states. The outcome is a fragmented and unequal territorial configuration, where the resulting artificial oases occupy 3% and concentrate more than 95% of the population. The consequences are the degradation of the Guanacache system, making it imperative to implement comprehensive regional policies for its restoration. Therefore, the objectives of the present work are to quantify the temporal variations in the streamflow and spatial extent of the water bodies of the lagoon system, to explore the relationship with climatic fluctuations that modulate the regional surface hydrology over the last few years, and to establish the role of the construction of various engineering infrastructures such as reservoirs and canals for water distribution in regional water variations. [ABSTRACT FROM AUTHOR]

Laboratory experiments were conducted to determine the thermal tolerance of the living ostracod Cyprideis sp. from a lagoon known as Murray's Pool on the east coast of Bahrain, in the western Arabian Gulf. Our experimental trials, run in duplicate using a semi-controlled thermal incubator, demonstrate the resilience of the ostracod community to elevated temperatures. We observed that ostracod specimens begin to enter an inactive condition or become comatose at about 39.4 °C, and with increase in temperatures, half of the specimens died or did not recover at 51.8 °C. At 53.5 °C, total mortality is observed with no indication of recovery. These observations have implications for climate change predictions in the western Gulf region, as water temperatures in the lagoon reach 42 °C in summer, while the substrate temperatures on mud flats exposed during low tide exceed the lethal limit of the ostracods during the summer months. [ABSTRACT FROM AUTHOR]

The impacts of climate change and the increasing occurrence of consequent extreme events in recent years have led to significant environmental, social and economic consequences in a fragile and highly vulnerable territory such as Venice. It is precisely in this perspective, which considers areas particularly vulnerable to the effects of climate, that the scientific research program Venezia2021, coordinated by CORILA - Consortium for Coordination of Research Activities concerning the Venice lagoon system, is inserted. The research in question involves a complex process of identification and integration of innovative tools, data processing and analysis and assessment of impacts, in order to contribute to the maintenance of a proper balance of the lagoon ecosystem in a perspective of increased climate resilience. The overall objective of the research was to build a strategic, accurate and shared vision with respect to the challenges that await the preservation of the city and its lagoon, (a World Heritage Site), in consideration of climate change scenarios. Specifically, this paper analyzes the research experience of thematic axis No. 5 that led to the drafting of the Climate Change Adaptation Plan for the Venice Lagoon. The operational path that led to the construction of the plan was guided by an in-depth spatial study and development of an integrated system of analysis, assessment, planning, management and monitoring of the Venetian area capable of supporting the city and the activities that operate in it, through coordinated adaptation actions aimed at increasing sustainability and resilience as a whole. [ABSTRACT FROM AUTHOR]

As part of a long-term study on the effects of nitrogen (N) loading in a shallow temperate lagoon, we measured rates of N2 fixation associated with seagrass (Zostera marina) epiphytes during the summer from 2005 to 2019, at two sites along a gradient from where high N groundwater enters the system (denoted SH) to a more well-flushed outer harbor (OH). The data presented here are the first such long-term N2 fixation estimates for any seagrass system and one of the very few reported for the phyllosphere in a temperate system. Mean daily N2 fixation was estimated from light and dark measurements using the acetylene reduction assay intercalibrated using both incorporation of 15N2 into biomass and a novel application of the N2:Ar method. Surprisingly, despite a large inorganic N input from a N-contaminated groundwater plume, epiphytic N2 fixation rates were moderately to very high for a seagrass system (OH site 14-year mean of 0.94 mmol N m−2 d−1), with the highest rates (2.6 mmol N m−2 d−1) measured at the more N-loaded eutrophic site (SH) where dissolved inorganic N was higher and soluble reactive phosphorus was lower than in the better-flushed OH. Over 95% of the total N2 fixation measured was in the light, suggesting the importance of cyanobacteria in the epiphyte assemblages. We observed large inter-annual variation both within and across the two study sites (range from 0.1 to 2.6 mmol N fixed m−2 d−1), which we suggest is in part related to climatic variation. We estimate that input from phyllosphere N2 fixation over the study period contributes on average an additional 20% to the total daily N load per area within the seagrass meadow. [ABSTRACT FROM AUTHOR]

The Lagoa Salgada is located in the Paraíba do Sul river delta plain on the coast of Rio de Janeiro state, Brazil, and is one of the few lagoons in the world that have well-developed recent stromatolites. Lagoa Salgada is a hypersaline lagoon formed in a very complex environmental system subjected to terrestrial and oceanic influences under different sea level regimes and climate variations. In addition, sediment and stromatolites are characterized by unusually positive inorganic δ13C VPDB values. For this reason, it has been the target of several geological and paleoenvironmental studies, which, in their great majority, require a geochronological technique in order to determine the changes in the environment over time. When radiocarbon (14C) dating is used, it is necessary to consider some details as the source of 14C in the environment and perform 14C ages calibration accordingly. In the present paper, a bibliographic survey was carried out in order to review the data treatment and improve the environmental evolution discussion based on accurate calibration. Using the Marine20 curve and an undetermined ΔR, we generated growth and depositional models to establish an overview of the formation of this lagoon. [ABSTRACT FROM AUTHOR]

Mediterranean coastal lagoons provide important ecological functions and nature's contribution to people, but they are particularly vulnerable to multiple pressures due to their location at the land-sea interface and the many activities they host. Numerous research and monitoring programs have been conducted to study the functioning of Mediterranean coastal lagoons and to improve their ecological and chemical status, especially since the 2000s with the EU Water Framework Directive. However, many coastal lagoons still had not achieved a good ecological status by 2018. The soft-bottom benthic ecosystem plays a crucial role in the functioning of shallow coastal lagoons, regulating among others nutrient and oxygen fluxes, and hosting a high biodiversity. The alteration of this compartment by anthropogenic pressures is therefore a major problem. Through a literature review, this paper aims to summarize information available on the impacts of the five main human-induced pressures — i.e. exploitation of natural resources, habitat destruction, climate change, pollution and alien invasive species — on the soft-bottom benthic ecosystem in Mediterranean coastal lagoons (period 2000—2022), and to identify perspectives for future research that can contribute to the improvement of monitoring programs. Our review shows that resource exploitation and nutrient pollution have been the two most studied pressures whereas research is still underdeveloped on the impacts of climate change, invasive alien species, and contaminants of emerging concern. We also found that the recording and quantification of pressures is still poor, and that their cumulative effect is poorly understood. In terms of indicators, the microbial and microphytobenthic compartments are being overlooked and functional approaches could be strengthened. This review could help scientists realign research on pressures of priority interest and thus better assist stakeholders in managing coastal lagoons in times of global changes. [ABSTRACT FROM AUTHOR]

The Baltic Sea faces prolonged eutrophication due to nutrient pollution, with the Nemunas River regulating nutrient input via the Curonian Lagoon. In this study, we aimed to assess the seasonal variations and changes over the past two decades in nutrient concentrations within the Curonian Lagoon–Baltic Sea transitional zone, and to identify the main factors affecting these trends. We observed slightly reduced nutrient levels in the lagoon and the Klaipėda Strait and increased nitrogen loadings in the Baltic Sea nearshore over time. Between 2007 and 2009, the average total nitrogen (TN) concentrations in the Klaipeda Strait and the Baltic Sea were 1.60 ± 0.25 and 0.54 ± 0.04 mg/L, respectively, while the average total phosphorus (TP) concentrations in the Klaipeda Strait and the Baltic Sea were 0.061 ± 0.04 and 0.03 ± 0.01 mg/L, respectively. Between 2018 and 2020, TN concentrations in the Strait and the Sea were 1.2 ± 0.36 and 0.65 ± 0.32 mg/L, respectively, while the average TP concentrations in the Klaipeda Strait and the Baltic Sea were 0.025 ± 0.002 and 0.021 ± 0.002 mg/L, respectively. The average annual amount of TN and TP entering the Curonian Lagoon from the sea was 2736 t and 162 t, respectively. Significantly higher nutrient influx to the Baltic Sea was recorded reaching 32,302 t for TN and 1278 t for TP. Nutrient concentrations correlated with water temperature, salinity, and dissolved oxygen, influenced by seasonal runoff patterns and climate change. Over time, there have been noticeable shifts in environmental conditions, including rising temperatures, decreasing oxygen levels, salinity changes, increased evaporation, and reduced precipitation. [ABSTRACT FROM AUTHOR]

Background: Seagrass meadows provide valuable ecosystem services but are threatened by global change pressures, and there is growing concern that the functions seagrasses perform within an ecosystem will be reduced or lost without intervention. Restoration has become an integral part of coastal management in response to major seagrass declines, but is often context dependent, requiring an assessment of methods to maximise restoration success. Here we investigate the use of different restoration strategies for the endangered Zostera capensis in South Africa. Methods: We assessed restoration feasibility by establishing seagrass transplant plots based on different transplant source materials (diameter (ø) 10 cm cores and anchored individual shoots), planting patterns (line, dense, bullseye) and planting site (upper, upper-mid and mid-intertidal zones). Monitoring of area cover, shoot length, and macrofaunal diversity was conducted over 18 months. Results: Mixed model analysis showed distinct effects of transplant material used, planting pattern and site on transplant survival and area cover. Significant declines in seagrass cover across all treatments was recorded post-transplantation (2 months), followed by a period of recovery. Of the transplants that persisted after 18 months of monitoring (~58% plots survived across all treatments), seagrass area cover increased (~112%) and in some cases expanded by over >400% cover, depending on type of transplant material, planting arrangement and site. Higher bioturbator pressure from sandprawns (Kraussillichirus kraussi) significantly reduced transplant survival and area cover. Transplant plots were colonised by invertebrates, including seagrass specialists, such as South Africa's most endangered marine invertebrate, the false-eelgrass limpet (Siphonaria compressa). For future seagrass restoration projects, transplanting cores was deemed the best method, showing higher long-term persistence and cover, however this approach is also resource intensive with potentially negative impacts on donor meadows at larger scales. There is a clear need for further research to address Z. capensis restoration scalability and improve long-term transplant persistence. [ABSTRACT FROM AUTHOR]

Planktonic heterotrophic prokaryotes (HProks) are a pivotal functional group in marine ecosystems and are highly sensitive to environmental variability and climate change. This study aimed to investigate the short-term effects of increasing carbon dioxide (CO2), ultraviolet radiation (UVR), and temperature on natural assemblages of HProks in the Ria Formosa coastal lagoon during winter. Two multi-stressor microcosm experiments were used to evaluate the isolated and combined effects of these environmental changes on HProk abundance, production, growth, and mortality rates. The isolated and combined effects of increased CO2 on HProks were not significant. However, HProk production, cellular activity, instantaneous growth rate, and mortality rate were negatively influenced by elevated UVR and positively influenced by warming. Stronger effects were detected on HProk mortality in relation to specific growth rate, leading to higher HProk net growth rates and abundance under elevated UVR and lower values under warming conditions. [ABSTRACT FROM AUTHOR]

In this study, an ensemble of numerical simulations with a state-of-the-art hydrodynamic model for coastal applications is used to characterize, for the first time, the expected mid-21st-century changes in circulation and associated sea-level height inside the Venice lagoon induced by projected Mediterranean sea level rise and atmospheric circulation changes over the Adriatic Sea under the RCP8.5 emission scenario. Our results show that water transports through the three inlets connecting the Venice lagoon to the open sea are expected to change significantly, with consequent significant persistent alterations of the circulation and sea-level height inside the lagoon. The projected water mass redistributions motivate further studies on the implications of climate change for the lagoon environment. [ABSTRACT FROM AUTHOR]

Mediterranean coastal lagoons are particularly vulnerable to increasing direct anthropogenic threats and climate change. Understanding their potential responses to global and local changes is essential to develop management strategies adapted to these ecosystems. Salinity is a fundamental structuring factor for phytoplankton communities; however, its role under climate change is understudied. We hypothesized that salinity variations imposed by climate change and/or management actions could disturb Mediterranean lagoons' phytoplankton communities. To test our hypothesis, we performed two 5-day microcosm experiments in which natural phytoplankton assemblages from the Santa Giulia lagoon (Corsica Island) were subjected to three increasing (53–63–73) and decreasing (33–26–20) levels of salinity, to mimic strong evaporation and flash flooding, respectively. Results indicate that over-salinization inhibited growth and modified the assemblages' composition. Freshening, on the contrary, showed feeble effects, mainly boosting microphytoplankton abundance and depleting diversity at lowest salinity. In both experiments and under freshening in particular, initially rare species emerged, while photosynthetic activity was degraded by salinity increase only. We demonstrated that phytoplankton communities' structure and metabolism are strongly altered by the predicted implications of climate change. Such impacts have to be considered for future management of coastal lagoons (control of sea exchanges and watershed fluxes). This work constitutes a priority step towards the proactive adapted management and conservation of such as-yet-neglected ecosystems in the context of climate change. [ABSTRACT FROM AUTHOR]

The urban lagoons receive strong anthropic pressures and the tensions often coexist between the "urban" and the "natural," and this consequently generates pollution and risks to the environment and human health. Our main objective was to study the water quality and to assess the bacteriological and eutrophication risks in the temperate shallow urban lagoon of the Parque Unzué (Gualeguaychú, Argentina), and to predict these risks in climate change scenarios considering the temperature and the rains as indicators. This urban shallow lagoon is in a recreative multiuse park (Gualeguaychú city), in the floodplain of the Gualeguaychú river in the Center-East of Argentina (Neotropical region). Twenty-seven sampling in 3 sampling points (n = 81) were carried out during 2015–2019, and physicochemical and bacteriological parameters were measured. Phosphorus, organic matter, chlorophyll-a (Chl-a), and total coliforms (TC) frequently had a moderate and very high contamination factor (CF), and the pollution load index (PLI) indicated contamination with a frequency of 74.1 %. Moreover, the index (WQI) indicated poor (66.7 %) and good (33.3 %) water quality. Bacteriological and eutrophication predictive risk models showed an increase of the TC and the Chl-a concentration generating a current and future high risk of contamination of the lagoon under climate change scenarios that could generate ecosystemic function losses in the short-term. [ABSTRACT FROM AUTHOR]

Venice has a pluricentennial history of modifying the morphology of its lagoon and hydrographic basin. This uniqueness only partially relates to the cyclopean works that, since the early 17th century, led to the deviation of the mouths of all the main rivers from the lagoon (to prevent its filling) and the erection of dikes (to protect the littoral from erosion). The lagoon's most significant feature is the non-despotic, non-vexatious, public, bureaucratic, and conservationist water management system run by the Republic of Venice. The most tangible evidence of this unique system of water management is composed of a hundred humble markers that punctuate what used to be (and mainly still is) the conterminazione lagunare, the area under the control of the Magistrato alle Acque (the Venetian Magistracy for the Waterways). Comparing the borders of the lagoon today with the path traced by these defining markers allows for an appreciation of the enduring challenges that this complex environment faces and will continue to face. This globally relevant case study of Venice and its lagoon encourages timely reflection on the effects of climate change on cultural heritage. [ABSTRACT FROM AUTHOR]

The Indian River Lagoon National Estuary Program has determined the principal factors that have historically degraded water quality and ecosystem function can be mitigated by nine adaption actions focused on reducing nutrient pollution from surface- and storm-water runoff, on-site sewage treatment systems and waste-water treatment plants. If properly sited and designed, the resiliency of these projects under conditions of climate change will be enhanced, as will the probability they will perform as intended throughout their design life. Analysis of the predominate remediation strategies currently pursued within the IRL watershed suggests their environmental contribution and duration of performance is proportional location, scale, and cost. [ABSTRACT FROM AUTHOR]

Coastal lagoons are recognized as specific and complex water bodies vulnerable to climate change. The focus of this study was the Curonian Lagoon, the largest freshwater lagoon in the Baltic Sea and the whole of Europe. The changes in the hydrometeorological parameters of the lagoon over six decades were evaluated using two periods of climatological standard normal: the most recent 30-year period, i.e., 1991–2020, and the period of 1961–1990. Before statistical analysis, data were checked for homogeneity, and breakpoints were determined by Pettitt and Buishand tests. The Mann–Kendall test was used to determine trends in the data series. The analysis revealed substantial changes in the hydrometeorological parameters of the lagoon during two climate normal periods. An exceptionally high rise in air temperature was detected. A considerable increase was identified in the lagoon water temperature and water level data series. The duration of permanent ice cover on the lagoon declined, as did the ice thickness, whereas the ice breakup advanced. A downward trend in wind speed data was detected, while the change in precipitation had a positive direction. Air and water temperatures were highly correlated with the Arctic Oscillation (AO) index and the water level with the Scandinavia pattern (SCAND). [ABSTRACT FROM AUTHOR]

The common cockle Cerastoderma edule is a widespread bivalve species inhabiting estuarine systems across the North East Atlantic, where it provides several ecosystem services, and represents a valuable fishery resource for local economies. However, anthropogenic pressure and more frequent extreme weather events threaten the resilience of the species. Spatially explicit information on species distribution is critical for the implementation of management and conservation practices. This study assessed the potential distribution of C. edule in the Ria de Aveiro by estimating the habitat suitability using an ensemble approach based on ecological niche modeling and recently developed hydrodynamic and water quality models to forecast both average and projected estuarine conditions. The models were developed for the summer of 2013 and spring of 2019 and potential range shifts in the species distribution were forecasted under projected environmental conditions: high and low estimates of freshwater discharge, a 2 °C increase in water temperature, and the combined effect of low freshwater discharge and increased water temperature. The results suggest that salinity, time of submersion, and current velocity play an important role in the distribution of cockles, and large areas were consistently classified with high habitat suitability. Increased freshwater discharge (both seasons) and low discharge coupled to increased temperature (spring) resulted in large decreases in suitable habitat. Conversely, low freshwater discharges and average (unchanged) temperatures increased the suitable habitat in the outermost regions of the Ria. The spatially explicit information provided contributes to a better understanding of the vulnerability of C. edule in the Ria de Aveiro to extreme weather events (e.g., droughts, river floods) and may support adaptive management strategies of the cockle fishery during these conditions. Moreover, this approach can be transferred to other estuarine ecosystems for which data describing the environmental conditions (e.g., derived from numerical models), and information about species presence are available (including data-poor species). [ABSTRACT FROM AUTHOR]

Cyanobacterial blooms are a potential threat to human communities and ecosystems. Since the late 1980s, researchers have reported harmful cyanobacterial colonies in Patos Lagoon (PL), the largest coastal lagoon in South America. Most studies concerning harmful blooms in PL have focused on its biology and on its southernmost estuarine region, with little information about its displacement inside the lagoon and the influence of physical forces on its dynamics. This study uses satellite-derived information (normalized difference chlorophyll-a index - NDCI), river discharge data, and meteorological data (wind speed and direction, rainfall, and air temperature) to analyze two bloom episodes in PL, during the austral summer of 2019/2020, specifically in its larger, limnic portion. A 30-year meteorological time series was used to contrast the same summer period. Two remote sensing images from Sentinel-2 were taken of PL margins, near their central portion. The summer of 2019/2020 was drier when compared with the historical data, characterizing low river discharge. This environmental condition was coupled with high temperature, which implies thermal stratification in summer even at 2-m depth sites, which might have promoted cyanobacterial growth and accumulation inside PL. Moreover, weak winds (<<6 m s-1) seemed to accumulate cyanobacterial patches on the water surface, including after vertical mixing caused by strong winds (>6 m s-1). The NDCI values represented the two days of blooms, with higher values occurring under higher water temperatures and low wind speeds. [ABSTRACT FROM AUTHOR]

The coastal plain of Cabo Frio is located in an area where natural elements coexist (lagoons, restinga vegetation, stationary and transgressive dunes, etc.) with the urban site of the municipality. By investigating the dynamics and behavior of the megaform parabolic, an asymmetry was observed in its displacement over the plain, with different migration rates: 12.2m/year along its central axis, and 7.3m/year on the avalanche face. In terms of area coverage, it experienced a loss of 9.4 ha, resulting in a decrease of 13.6%. In addition to human presence, coastal environments can also be sensitive to environmental changes such as climate change and wave climates, which may lead to a landscape transformation process in this área. [ABSTRACT FROM AUTHOR]

Lipid-biomarkers have been used to reconstruct environmental changes in lacustrine systems on a range of time scales. Lake sediments are excellent archives to apply these tools due to their rapid and amplified response to environmental pressures. For the past thirty years, the hypersaline lagoons of the Rio de Janeiro coastal plain have been studied as natural laboratories for the observation of the biogeochemical processes involved in modern dolomite precipitation. Here, we apply a multiproxy approach to characterize two depositional stages during the Holocene that may have triggered primary dolomite formation in these lagoonal environments. A first stage, with two sub-stages (1A − 6.1 to 4.2 kyr. BP; 1B − 4.2 to ∼3.6 kyr. BP) was deposited during the sea-level rise, with sediments containing an abundance of long-chain n -alkanes with 2H-depleted (δ2H n -alk) signatures indicating riverine inputs of terrestrial organic carbon during prevailing wet conditions. A second stage (<∼3.6 kyr. BP), comprising lacustrine facies, was characterized by high amounts of authigenic carbonate precipitates (calcite, Mg-calcite, Ca-dolomite, and dolomite). The carbonates are the result of physico-chemical changes in the water after the isolation of the lagoons from both the Atlantic Ocean and the neighboring Lagoa de Araruama due to a fall in sea level and aridification associated with intensification of the coastal upwelling after 2.2 kyr. BP. The n -alkanes deposited during this phase contain variable proportions of long and short-chain homologues indicating a mixed source of organic matter (terrestrial higher plants and microorganisms), as well as changes in vegetation associated with the driest conditions, inferred from the 2H-enriched n -alkane homologous. These results clearly demonstrate a climatic influence on dolomite formation in coastal hypersaline environments linked to sea-level change and coastal upwelling phenomena. With these observations, we hypothesize that the existence of similar palaeoceanographic and environmental conditions in the geologic past may have triggered the formation of extensive microbial dolomite deposits. This study provides new elements to interpret the formation of massive dolomite deposits in the geological record, for example, along the Late Triassic Tethys margin. [ABSTRACT FROM AUTHOR]

Global climate change is expected to affect precipitation patterns over Southeastern South America, increasing the number and intensity of heavy rainfalls. We aimed to identify short-term effects of very heavy rainfall events (VHREs) on abiotic and biological indicators of water quality in Rodrigo de Freitas Lagoon (RFL; Rio de Janeiro, Brazil). Our hypothesis is that VHREs alter water parameters reducing the overall quality of lagoon. A before-and-after effect design was applied by compiling mean weekly data of four abiotic and three biological indicators for 1st and 2nd weeks before and 1st and 2nd weeks after VHRE. One extreme and 15 VHREs were detected from 2018 to 2019, directly interfering on the stormwater input into RFL. Particular water conditions after VHREs were mainly related to increased Escherichia coli density and decreased dissolved oxygen and phytoplankton abundance. Moreover, shifts in relative contribution of phytoplanktonic groups were significantly detected. We successfully identified short-term effects of VHREs on biological and hydrological indicators of water quality in RFL, which have partially supported our hypothesis. Predictions of increased rainfall intensity and frequency of extreme events may lead to harsher and unpredictable changes in ecosystem functioning and lagoon conditions that may impair aquatic biodiversity and fisheries. [ABSTRACT FROM AUTHOR]

The coastlines of the southwestern Pacific are dynamic environments that have been repeatedly reshaped by tectonic forces as well as changing global climate and sea level. It has been theorized that much of the north coast of New Guinea was sparsely inhabited until stabilization of coastal flats fallowing the Mid-Holocene Thermal Maximum and resulting marine high stand. We report on environmental proxy indicators measured in core samples taken near modern day Aitape, Papua New Guinea. These cores record the formation of a large lagoonal system on the modern coastal flats by 5800 cal BP. This lagoon infilled over the next several 1000 years as sea level dropped, with the modern coastal flats stabilizing by 1400 cal BP. A charcoal record spanning the period between 6200 and 1400 cal BP documents substantial increases in influx between ~6200 and 6000 cal BP and particularly from ~3000 to 2600 cal BP. Comparison to regional charcoal and ENSO records suggests that increasing aridity and ENSO intensity may drive regional patterning in fire records, however, localized charcoal records are also heavily influenced by human activity. Between 3000 and 2600 cal BP, forest management practices in the Aitape area, currently focused on tree crops and horticulture characterized by long fallowing and limited burning, shifted to a regime characterized by large scale forest clearance and shorter fallowing. We hypothesize that increasing population driven by abundant Mid-Holocene lagoonal resources may have been difficult to maintain as lagoons infilled and climate became more variable, leading to horticultural intensification. [ABSTRACT FROM AUTHOR]

Precipitation changes in the East Asia are closely linked to the monsoonal climate in this region and the hydrothermal processes in the western tropical Pacific. However, trends of reconstructed precipitation records for the past millennium are inconsistent and the influencing factors are in dispute. Here we reconstruct a 700-year precipitation record for the northern South China Sea (SCS) using grain size of lagoon sediments. Our data revealed that precipitation increased in the early to middle Little Ice Age, possibly modulated by tropical cyclones and the Walker Circulation. The East Asian Summer Monsoon and Pacific Decadal Oscillation had the major influence on the precipitation changes in the northern SCS. This study provides new insight into the processes and the underlying mechanisms of climate changes in the SCS. • Providing a 700-year record of precipitation in the northern South China Sea (SCS) based on lagoon sediments. • The precipitation increased in the early to middle LIA, which may have been influenced by TCs and the Walker Circulation. • Our reconstruction shows that the EASM and tht PDO have a major influence on precipitation in the northern SCS. [ABSTRACT FROM AUTHOR]

In California (USA), seasonal lagoons provide important oversummer rearing habitat for juvenile steelhead trout (anadromous Oncorhynchus mykiss). However, key water quality parameters such as temperature and dissolved oxygen concentration can periodically approach or exceed the physiological tolerances of steelhead during the protracted dry season. A field study employing distributed temperature sensing technology, water quality monitoring, habitat mapping, and mark-recapture sampling was conducted to examine how shifting environmental conditions affected the performance and behavior of juvenile steelhead in the Scott Creek estuary/lagoon (Santa Cruz County). Abiotic conditions were driven by episodic inputs of seawater to the typically freshwater lagoon. During midsummer, the water column was vertically stratified which reduced suitable lagoon rearing habitat by approximately 40%. Nevertheless, steelhead abundance, growth, and condition factor were high during the summer and decreased in autumn following lagoon destratification and cooling. Unlike previous work, this study identified limited emigration from the lagoon to riverine habitat during the summer. Instead, juvenile steelhead exhibited crepuscular movement patterns within the lagoon, with peaks in upstream (to upper lagoon habitat) and downstream (to lower lagoon habitat) movement occurring at dawn and dusk, respectively. This study underscores that habitat complexity and connectivity are critical for juvenile steelhead production and persistence and provides insight into steelhead habitat use and behavior in seasonal lagoons. [ABSTRACT FROM AUTHOR]

Khor Al-Zubair lagoon is a vital water body in southern Iraq. Despite the existence of a number of environmental studies in this region, it lacks searches related to the diversity of diatoms especially benthic forms, in light of global climatic changes and their impacts on aquatic ecosystems. Therefore, this research was designed to document diatom species that began to colonize this lagoon. The present study was carried out during the period from January to November 2020 in two selected stations at Khor Al-Zubair lagoon, where five species of diatoms were documented and described, including Amphora acuta, Biremis ambigua, Cyclotella litoralis, Lyrella lyra var. subcarinata, and Progonoia musca. The species, C. litoralis is a new record for Iraqi diatom flora. [ABSTRACT FROM AUTHOR]

Coastal wetlands are declining globally, and although wetland restoration looks to offset these losses, its success relies on anticipating environmental response to external forces. The purpose of this study is to investigate the sedimentological record of Los Peñasquitos Lagoon to determine the processes that drive environmental transitions in a Southern California coastal wetland. For this project, we analyze three sediment cores from the wetland for grain size, total organic matter, and shell assemblages to reconstruct environmental change over the past ~4000 years. From the results, we find that the lagoon was initially an open embayment that persisted for >2000 years; however, at ~1000 cal yrs BP, a short-lived wet climatic period triggered a fluvial deltaic progradation at the head of the lagoon. As the wet period ended and drier conditions returned, the delta began to retreat, and the lagoon infilled as the estuarine mouth bar was permanently established. The permanent establishment of the mouth bar resulted in a transition to a marsh-dominated environment throughout the wetland. Ultimately, these environmental transitions were driven by climate variability, although evidence of human impacts was observed more recently in the record. Therefore, future restoration efforts must consider both natural climatic variability and anthropogenic influences if they intend to sustain coastal wetlands. [ABSTRACT FROM AUTHOR]

The modern Nile delta developed in the Middle and Late Holocene, and at its most northern-central point is situated at the Burullus Lagoon, which is environmentally diverse, including salt marshes, mudflats, and sand plains, and separated from a sea by a sand barrier overtopped with high sand dunes. The lagoon has been fed since the Middle Holocene by the Sebennitic branch of the Nile and marine intrusions through the Bughaz inlet. A sediment core (BO-1) was collected at the northeastern shore of the lagoon and sampled at centennial scale resolution in order to reconstruct the development of the lagoon. The results show that an initial and limited lagoon had developed at the end of the Early Holocene, but after a dry period ca. 7.2 cal ka BP it has been progressively transformed into a marshy area, with occasional inflows of sea water. Lower water level and higher salinity of the Burullus Lagoon at 6.0-5.5 and 4.8-4.2 cal ka BP reflected droughts in the Nile catchment. Thereafter, the river reactivated in the Burullus Lagoon area, and since 2.8 cal ka BP was accompanied by occasional inflows of sea water. Since ca. 0.8 cal ka BP, increased fluvial activity occurred in this part of the Nile delta, which terminated after construction of the Aswan dams in the twentieth century. [ABSTRACT FROM AUTHOR]

The Venice lagoon (Italy) is particularly vulnerable to the impact of subsidence and sea level rise driven by climate change. Some structural measures have been adopted over time to protect Venice from flooding, among which a system of flap gates (Experimental Electromechanical Module, Mo.S.E., system) has been operational in the testing phase since October 2020. However, relative sea level rise and wind set-up pose relevant management challenges, as a frequent closing of the lagoon would have negative impacts on flushing capacity, the fishing industry, and port activities. Here, the focus is on the hydrodynamic effects of a partial closure of the Mo.S.E. barriers that, compared to closing all the three inlets of the lagoon, could play a role in reducing the economic and environmental impacts of the Mo.S.E. system. The main goal is to identify the flooding events that can be counteracted by closing only the Lido inlet, which is the closest to the city of Venice. Based on the tidal and meteorological dataset collected in the period 2000–2019, a robust modelling exercise identifies a linear relationship between tidal range and reduction of the sea level peaks, which results in the protection of all urban settlements within the lagoon from two-thirds of the flooding events up to a relative sea level rise of + 0.4 m. [ABSTRACT FROM AUTHOR]

This paper provides an analysis of climate change's impact on small businesses in the Madang Lagoon area. The study used quantitative methodology. The quantitative data were collected using a self-administered questionnaire. The study used non-probability sampling which combined convenience and snowball sampling that are popular sampling techniques. The completed questionnaires were retrieved and coded on an ordinal scale of 1 to 5 manually on the questionnaire and entered the codes into a specially designed excel spreadsheet and raw data were transferred to the Scientific Package for Social Science (SPSS) software and generated the reports. The study found that majority of the small businesses were affected by climate change and some businesses have had to close operations and others diversify into other small businesses. About 78% of businesses were owned and operated by women who support their family to meet the daily needs. All the small businesses were classified as being in the informal sector. The study also found that the environmental impact of climate change is evident in the study areas but little or nothing is done to prevent further damage caused by coastal erosion. As per responses from respondents, there is a plan, but nothing has been done so far to mitigate and adapt to climate change challenges. The study provides a better understanding of climate change impacts on the natural environment and small businesses. [ABSTRACT FROM AUTHOR]

The carbonate chemistry was investigated in the semiarid eutrophic Araruama Lagoon (Brazil), one of the largest hypersaline coastal lagoons in the world. Spatial surveys during winter and summer periods were performed, in addition to a diurnal sampling in summer. The hypersaline waters have higher concentrations of total alkalinity (TA) and dissolved inorganic carbon (DIC) than the seawater that feed the lagoon, due to evaporation. However, TA and DIC concentrations were lower than those expected from evaporation. Calcium carbonate (CaCO3) precipitation partially explained these deficits. The negative correlation between the partial pressure of CO2 (pCO2) and chlorophyll a (Chl a) indicated that DIC was also consumed by primary producers. The uptake by photosynthesis contributes to 57–63% of DIC deviation from evaporation, the remaining credited to CaCO3 precipitation. Marked pCO2 undersaturation was prevalent at the innermost region with shallow, confined, and phytoplankton-dominated waters, with a strong enrichment of heavier carbon isotope (δ13C-DIC up to 5.55‰), and highest pH (locally counter-acting the process of ocean acidification). Oversaturation was restricted to an urbanized region, and during night-time. The lagoon behaved as a marked CO2 sink during winter (− 15.32 to − 10.15 mmolC m−2 day−1), a moderate sink during summer (− 5.50 to − 4.67 mmolC m−2 day−1), with a net community production (NCP) of 93.7 mmolC m−2 day−1 and prevalence of net autotrophic metabolism. A decoupling between CO2 and O2 exchange rate at the air–water interface was attributed to differences in gas solubility, and high buffering capacity. The carbonate chemistry reveals simultaneous and antagonistic actions of CaCO3 precipitation and autotrophic metabolism on CO2 fluxes, and could reflect future conditions in populated and semiarid coastal ecosystems worldwide. [ABSTRACT FROM AUTHOR]

Macrophytes play an important role in providing habitat structure, nutrient cycling and improvement of water quality in freshwater ecosystems. However, increasing human population and the industrial revolution during past several centuries have increased the utilization of natural resources and have caused strong changes in the structure and function of the environment, such as high sedimentation that decreases light penetration. This study investigated the effects of in situ experimental shading on photosynthetic performance of submerged Elodea canadensis macrophytes and identified the level of light that is critical for growth and photosynthesis of this species. Photosynthetic performance, chlorophyll a and b concentrations, organic and carbon contents, percentage cover, and morphology were estimated in E. canadensis from middle of Songkhla lagoon under 4 treatments (25, 50, 75, and 100% of natural light) for 10 weeks. The results show that there were no differences in growth and photosynthesis among the treatments, but low light led to changes in chlorophyll concentration, Fv/Fm, and Ik, suggesting adaptations to a low light regime. This study provides an understanding of physiological tolerance and response to shading and shows how species of aquatic macrophytes respond to future climatic and anthropogenic changes, thereby supporting development of sustainable lagoon management plans. [ABSTRACT FROM AUTHOR]

Macrophytes play an important role in maintaining high physical and biological diversity in freshwater ecosystems. However, during the past several centuries since the industrial revolution, human activities and climate change have caused significant changes in the structure and function of aquatic environments, for example via increased temperature or high sedimentation that reduces light penetration. This study investigated the combined effects of elevated temperature and low light on growth and photosynthetic performance of submerged macrophytes Ceratophyllum demersum and Elodea canadensis and identified temperature and light thresholdsfor these species. Photosynthetic performance, chlorophyll a and b concentrations, organic and carbon contents, and growth rates were estimated in these two dominant macrophytes sampled from the middle of Songkhla lagoon, subjected to 9 treatments (3 light intensities and 3 temperatures) for 9 weeks. The results show that photosynthetic performance according to the indicators EQY, α and rETRmax was inhibited by low light in both species. C. demersum was more tolerant to temperature and light stresses. This study provides an understanding of physiological tolerance and response to light and temperature stresses, and improves the understanding of how aquatic macrophytes respond to future climatic and anthropogenic changes, supporting the development of sustainable lagoon management plans. [ABSTRACT FROM AUTHOR]

Estuaries are especially sensitive to climate change because they are located at the landsea interface and therefore water quality, habitat value, and ecosystem function are largely determined by what is being input to the basin from the adjacent terrestrial and marine environments. As climate changes, estuarine resilience is likely to be compromised as upland rainfall and river flow patterns change, air and water temperatures rise, intensity and frequency of tropical storm and hurricane landfalls increase, pH declines, and sea-level rises. Here, we demonstrate that future risks to the biodiversity of the Indian River Lagoon, Florida, caused by climate change can be effectively mitigated by implementing nine adaptation actions. Each was designed to reduce septic, wastewater, and surface water pollutant loadings that are expected to increase in response to one or more of the three principle climate change stressors identified during this evaluation: changes in precipitation, increasing storminess, and sea-level rise. By reducing pollutant loadings from these three sources, impairments to water quality and their deleterious effects on biodiversity will be ameliorated. Implementation and management of these plans will require a substantial increase in funding that is coherently managed for decades. Strengthened collaboration between local, state, and federal programs will be necessary to enhance the probability of success. [ABSTRACT FROM AUTHOR]

We present a continuous ∼7000-year sedimentary record from Lashmars Lagoon, Kangaroo Island (Karti/Karta), southern Australia, a region heavily impacted by drought and bushfires in recent decades. Records such as this are vital to contextualise current climatic and environmental shifts, particularly regarding the interplay between hydroclimate and fire-related disturbances in this ecologically sensitive area. We use high-resolution μX-ray fluorescence core scanning, complemented by bulk organic geochemistry and X-ray diffraction mineralogy of catchment soil and lake sediments to reconstruct past climate and catchment processes. Phases of elevated sediment organic matter content (inferred from high Br and total organic carbon) suggest increased lake freshening and productivity, and coincide with increased chemical weathering (inferred from high Al/K and kaolinite/illite and feldspars), likely reflecting the influence of wetter climates. Conversely, periods of high Ca correlate with biogenic carbonate inputs typical of brackish conditions, which we attribute to drier climates or a marine influence. From 7.0 ka, at the mid-Holocene sea level highstand, until 5.7 ka, we suspect Lashmars Lagoon was under virtually continuous influence from the sea. At 5.7 ka, we interpret the abrupt increase in sediment total organic carbon to reflect the severance of the connection to the sea, allowing organic material to accumulate. This, coupled with evidence of high inferred chemical weathering, suggests the climate was relatively wet at the time. After 5.4 ka, our data point to the establishment of drier conditions until the commencement of wetter climates again at 4.5 ka. From 2.5 ka, however, drier climates prevailed again until present. Notably, the climate changes recorded in the sedimentary sequence at Lashmars Lagoon seem to be linked to the strength of the Leeuwin Current, a current that brings warm tropical waters to southern Australia and demonstrates a teleconnection with the El Niño Southern Oscillation, and may well have been an important driver of rainfall on Kangaroo Island (Karti/Karta) over the past ∼7000 years. • Our record archives ∼7000 years of climate and catchment change in South Australia • Geochemical analyses are used to infer past hydroclimate and marine influence • We infer a distinctive wet period on Kangaroo Island (Karti) from 4.5 to 2.5 ka • We find evidence for a late Holocene dry period commencing at ∼2.5 ka • The strength of the Leeuwin Current may explain patterns of rainfall at our site [ABSTRACT FROM AUTHOR]

Results of a vulnerability assessment of the Indian River Lagoon to climate change indicate future risks to water quality can be mitigated through adaptation actions targeting anticipated increases in pollutant loads from wastewater treatment plants, on site treatment and disposal systems, and surface water storage and conveyance infrastructure. Nine adaptation actions are recommended and if successfully implemented could reduce risks caused by climate change by fifty percent. The mitigating benefits of these actions are expected to cascade into other elements of the Lagoon, like living resources and habitats. The results and recommendations of this investigation are novel because they are based upon site-specific data and anticipated risks prioritized using a repeatable and defensible methodology. Furthermore, the focus and deliverables were informed by stakeholder involvement to facilitate utility to and implementation by resource practitioners. The next challenge is to implement, monitor, and revise each adaptation action as warranted. This will require a substantial increase in funding dedicated to the Lagoon's restoration and coherently managed for decades. Strengthened collaboration between local, state, and federal programs is necessary to enhance the probability of successfully reducing future climate-related water quality impairments and facilitating the emergence of a more resilient, climate-ready estuary. [ABSTRACT FROM AUTHOR]

The Chelonian lineage has been exposed to several climate change events along its evolutionary history, but the rapid contemporary change in climate patterns has the potential to erode turtle populations. This study focuses on (1) evaluating the climatically suitable area available for 15 species of mud turtles of the genus Kinosternon, and on (2) assessing whether or not these species retain their ancestral climate niche. Occurrence data was collected for these species and, using the Maxent algorithm and WorldClim bioclimatic variables, suitable present and future climatic niche areas were modeled. In addition, we also carried out climatic niche similarity analyses between pairs of species to evaluate whether these conserve their climatic niche. Our models suggest that most species of Kinosternon will lose a high proportion of their suitable habitat in the future. Most mud turtle species seem to conserve their climatic niche, suggesting the prevalence of niche conservatism in the group. Our results indicate that several mud turtle species could be at severe risk of disappearing over the next few decades due to the loss of climatically suitable areas and of the conservation of their climatic niches. [ABSTRACT FROM AUTHOR]

This paper discusses the impacts of Climate Change and anthropogenic activities on coastal lagoons in Ghana. Ghana's coastal lagoons provide unique ecosystem services. However, they are highly fragile and vulnerable to natural processes and anthropogenic activities. Climate Change impacts, such as increased temperatures, sea-level rise, storm surge and increased precipitation are likely to have ecological damage to lagoon ecosystems as a result of erosion, submergence of lagoon barriers, flooding and drying of the surrounding wetlands. Field observation, Geographic Information System modeling were among the methodology applied. The paper identified that anthropogenic activities and Climate Change would combine to have a serious future impact on lagoon ecosystems. Particularly, increased rainfall-induced flooding from the hinterland may be very injurious to the lagoon ecosystem, since the flood water may carry not only nutrients but also various contaminants and solid plastic waste generated by human activities around lagoons catchment into the lagoon channels. Besides, due to the barriers across most lagoon inlets, such polluted runoff water may not be able to flush out to sea, thus impacting negatively on the water quality of the lagoons. The paper proposes some adaptation strategies and recommends the early implementation of Climate Change adaptation strategies, coastal lagoon management measures to prevent potential future destructive impacts. [ABSTRACT FROM AUTHOR]

Ecosystems in shallow micro-tidal lagoons are particularly sensitive to hydrologic changes. Lagoons are complex transitional ecosystems between land and sea, and the signals of direct human disturbance can be confounded by variability of the climate system, but from an effective estuary management perspective, the effects of climate versus direct human engineering interventions need to be identified separately. This study developed a 3D finite-volume hydrodynamic model to assess changes in hydrodynamics of the Peel–Harvey Estuary, a large shallow lagoon with restricted connection with ocean; this was done by considering how attributes such as water retention time, salinity and stratification have responded to a range of factors, focusing on the drying climate trend and the opening of a large artificial channel over the period from 1970 to 2016, and how they will evolve under current climate projections. The results show that the introduction of the artificial channel has fundamentally modified the flushing and mixing within the lagoon, and the drying climate has changed the hydrology by comparable magnitudes to that of the opening of the artificial channel. The results also highlight the complexity of their interacting impacts. Firstly, the artificial channel successfully improved the estuary flushing by reducing average water ages by 20–110 d, while in contrast the reduced precipitation and catchment inflow had a gradual opposite effect on the water ages; during the wet season this has almost counteracted the reduction brought about by the channel. Secondly, the drying climate caused an increase in the salinity of the lagoon by 10–30 PSU (Practical Salinity Unit); whilst the artificial channel increased the salinity during the wet season, it has reduced the likelihood of hypersalinity (>40 PSU) during the dry season in some areas. The opening of the artificial channel was also shown to increase the seawater fluxes and salinity stratification, while the drying climate acted to reduce the salinity stratification in the main body of the estuary. The impacts also varied spatially in this large lagoon. The southern estuary, which has the least connection with the ocean through the natural channel, is the most sensitive to climate change and the opening of the artificial channel. The projected future drying climate is shown to slightly increase the retention time and salinity in the lagoon and increase the hypersalinity risk in the rivers. The significance of these changes for nutrient retention and estuary ecology are discussed, highlighting the importance of these factors when setting up monitoring programmes, environmental flow strategies and nutrient load reduction targets. [ABSTRACT FROM AUTHOR]

Egyptian Mediterranean coast hosts five shallow lagoons which play a vital role in the national economy. Lake Burullus is the second largest one that is located in the Nile Delta and is connected to the Mediterranean by a narrow outlet. This lagoon faces various anthropogenic-induced implications that threat its ecosystem and biodiversity. The prime objective of this study is investigating the impacts of future climate change (CC) on its characteristics. A 2-D hydro-ecological modeling for the lagoon was implemented, using MIKE21FM. The proposed model was calibrated and validated against the collected water quality records, for two successive years (2011–2013), at twelve monitoring stations throughout the lagoon. The simulations were executed for various parameters, including water depth, salinity, DO, BOD, and nutrient components. Six simulations from different regional climate models (RCMs) were obtained and examined to extract the most accurate climatic projections for the lagoon coordinates. These climatic estimates cover three Representative Concentration Pathways (RCPs) scenarios according to the IPCC's Fifth Assessment Report (AR5). A moderate sea level rise (SLR), locally projected offshore from the Nile Delta coast, was obtained. The validated model was forced with the climatic and SLR projections of 2 years representing the mid and long-term future of the twenty-first century. The model results showed that the developed model is an efficient tool to simulate the lagoon characteristics. The results of the modified model showed that CC has the potential to radically alter the physical and chemical structure of Lake Burullus. The results emphasized that the lagoon is expected to be warmer and more saline. The risk of oxygen depletion is firmly predictable with significant spatial differences of DO decreasing. A prolonged residence time is expected, accompanied by an increasing trend of phosphate and chlorophyll-a and a decreasing trend of nitrate. CC impacts on Lake Burullus should be considered in its urgently required management plan. [ABSTRACT FROM AUTHOR]

Coastal wetlands and lagoons are under pressure due to competing demands for freshwater resources and climatic changes, which may increase salinity and cause a loss of ecological functions. These pressures are particularly high in Mediterranean regions with high evaporative demand compared to precipitation. To manage such wetlands and maximize their provision of ecosystem services, their hydrologic balance must be quantified. However, multiple channels, diffuse surface water exchanges, and diverse groundwater pathways complicate the quantification of different water balance components. To overcome this difficulty, we developed a mass balance approach based on coupled water and salt balance equations to estimate currently unknown water exchange fluxes through the Gialova lagoon, southwestern Peloponnese, Greece. Our approach facilitates quantification of both saline and freshwater exchange fluxes, using measured precipitation, water depth and salinity, and estimated evaporation rates over a study period of 2 years (2016–2017). While water exchanges were dominated by evaporation and saline water inputs from the sea during the summer, precipitation and freshwater inputs were more important during the winter. About 40 % and 60 % of the freshwater inputs were from precipitation and lateral freshwater flows, respectively. Approximately 70 % of the outputs was due to evaporation, with the remaining 30 % being water flow from the lagoon to the sea. Under future drier and warmer conditions, salinity in the lagoon is expected to increase, unless freshwater inputs are enhanced by restoring hydrologic connectivity between the lagoon and the surrounding freshwater bodies. This restoration strategy would be fundamental to stabilizing the current wide seasonal fluctuations in salinity and maintain ecosystem functionality but could be challenging to implement due to expected reductions in water availability in the freshwater bodies supporting the lagoon. [ABSTRACT FROM AUTHOR]

Climate change is projected to have large impacts on natural capital and ecosystem services under scenarios of the IPCC. In the summer of 2016, elevated seawater temperatures triggered mass coral bleaching in Sekisei Lagoon, southern Japan. Based on data from field surveys and relevant websites, we mapped potential stocks of four major ecosystem services (fisheries production, aquarium fish production, recreational diving, and seaweed control) supplied by coral reef fishes before and after the bleaching event and predicted the possible future state of socio-ecological systems in the lagoon under climate change. We also evaluated whether current management options had mitigated the negative effects of extreme heating and coral bleaching on the potential stocks. Before the coral bleaching, the potential stock of recreational diving was estimated as 41.44 billion Japanese yen per year for the entire lagoon, while those of fisheries and aquarium fish productions were 2.10 billion and 15.03 billion yen, respectively. After bleaching, the four potential stocks including seaweed control decreased. The marine park zone and the extermination area of crown of thorns starfish mitigated changes in fish species richness and the value of recreational diving following coral bleaching. Extreme heating and coral bleaching are considered to be representative of a possible future state under global warming, and the results suggest that even management for local disturbances can mitigate the interactive effect of climate change on the potential stocks. Additional integrative management accounting for climate change and local stressors would be necessary for protecting ecosystem services in Sekisei Lagoon. [ABSTRACT FROM AUTHOR]

Climate change is impacting ecosystems worldwide. Estuaries are diverse and important aquatic ecosystems; and yet until now we have lacked information on the response of estuaries to climate change. Here we present data from a twelve-year monitoring program, involving 6200 observations of 166 estuaries along >1100 kilometres of the Australian coastline encompassing all estuary morphologies. Estuary temperatures increased by 2.16 °C on average over 12 years, at a rate of 0.2 °C year−1, with waters acidifying at a rate of 0.09 pH units and freshening at 0.086 PSU year−1. The response of estuaries to climate change is dependent on their morphology. Lagoons and rivers are warming and acidifying at the fastest rate because of shallow average depths and limited oceanic exchange. The changes measured are an order of magnitude faster than predicted by global ocean and atmospheric models, indicating that existing global models may not be useful to predict change in estuaries. Estuaries are diverse and important aquatic ecosystems, yet we lack information on their response to climate change. Here, the authors show that east Australian estuaries are warming and acidifying faster than predicted by ocean or atmospheric models; a trend that is magnified in shallow estuaries. [ABSTRACT FROM AUTHOR]

The identification and quantification of natural carbon (C) sinks is critical to global climate change mitigation efforts. Tropical coastal wetlands are considered important in this context, yet knowledge of their dynamics and quantitative data are still scarce. In order to quantify the C accumulation rate and understand how it is influenced by land use and climate change, a palaeoecological study was conducted in the mangrove‐fringed Segara Anakan Lagoon (SAL) in Java, Indonesia. A sediment core was age‐dated and analyzed for its pollen and spore, elemental and biogeochemical compositions. The results indicate that environmental dynamics in the SAL and its C accumulation over the past 400 years were controlled mainly by climate oscillations and anthropogenic activities. The interaction of these two factors changed the lagoon's sediment supply and salinity, which consequently altered the organic matter composition and deposition in the lagoon. Four phases with varying climates were identified. While autochthonous mangrove C was a significant contributor to carbon accumulation in SAL sediments throughout all four phases, varying admixtures of terrestrial C from the hinterland also contributed, with natural mixed forest C predominating in the early phases and agriculture soil C predominating in the later phases. In this context, climate‐related precipitation changes are an overarching control, as surface water transport through rivers serves as the "delivery agent" for the outcomes of the anthropogenic impact in the catchment area into the lagoon. Amongst mangrove‐dominated ecosystems globally, the SAL is one of the most effective C sinks due to high mangrove carbon input in combination with a high allochthonous carbon input from anthropogenically enhanced sediment from the hinterland and increased preservation. Given the substantial C sequestration capacity of the SAL and other mangrove‐fringed coastal lagoons, conservation and restoration of these ecosystems is vitally important for climate change mitigation. [ABSTRACT FROM AUTHOR]

Record drought from 2012 to 2016 followed by rainfall in the winter of 2017 provided an opportunity to examine how changing climate conditions may affect migration opportunities for the endangered southern steelhead trout (Oncorhynchus mykiss). This study examined how intermittently open estuary-ocean interfaces in the Santa Monica Bay that have historically supported steelhead evolved temporally and volumetrically. All seven lagoons in the study area breached by January 2017 after five years of drought and nearly exclusively closed conditions. Duration of breach was affected by the size of the lagoon, with smaller lagoons remaining breached longer than larger lagoons. Conversely, volume capacity persisted longer in larger lagoons. Lagoon condition was quantified by presence/absence of breach and passibility, coupled with daily rainfall. This study provides important lagoon planning, restoration and management information needed to support recovery of southern steelhead trout populations in the face of climate change. [ABSTRACT FROM AUTHOR]