Lagoon Ecosystem Research Articles

Phthalate esters in baltic lagoons: Spatial distribution, ecological risks, and novel insights into their fate using transcriptomics.

Plasticizers such as phthalate esters (PAEs) are organic compounds widely used in various consumer and industrial products, raising strong environmental concerns due to their pervasive presence and potential adverse effects. Lagoon ecosystems are particularly vulnerable to PAE pollution as they are semi-enclosed and receive high loads of organic materials. The present study investigates the distribution of seven common PAEs in three large European lagoons (Curonian, Vistula and Szczecin) in the southern Baltic Sea. The concentration levels of PAEs in the water column, encompassing both the dissolved and particulate-bound phases, and in sediments were assessed to elucidate distribution patterns and potential ecological risks within these lagoon ecosystems. The average concentration of total PAEs in the water column ranged from 0.03 to 1.45 μg L-1, whereas sediment concentration varied from 0.008 to 1.06 μg g-1, levels comparable to or lower than those found in other European coastal areas. Distribution patterns of PAEs in sediment showed notable similarity across all three lagoons, whereas variations were observed in the water column. Notably, di(2-ethylhexyl) phthalate (DEHP), di-n-octyl phthalate (DOP) and dimethyl phthalate (DMP) emerged as the most concerning congeners in studied lagoons, all of which pose a moderate risk to aquatic organisms. This study applied shotgun transcriptomic analysis to field samples, revealing active microbial communities involved in PAEs degradation in the Baltic lagoons for the first time. The degradation of phthalic acid (PA) into intermediate compounds such as protocatechuate was not identified as a rate-limiting step in the studied environment. The degradation activity was primarily localized in the sediment layers, with Gram-negative bacteria playing a major role, while Gram-positive bacteria appeared incapable of degrading PA. These findings provide valuable insights into the distribution and transformation mechanisms of PAEs in estuarine environments.

Arrested development and increased incidence of sandprawn embryonic aberrations along an intertidal human recreation gradient.

Anthropogenic pressures are increasing in coastal ecosystems globally, yet identifying robust indicators of change and managing coastal resources can be complicated by phenotypic plasticity and differential life-history responses of key organisms. We illustrate this using biogeochemical and sandprawn (Kraussillichirus kraussi) response metrics along a human recreation gradient (trampling, sandprawn harvesting) in a South African lagoonal ecosystem. Benthic compaction, oxygen depletion and high porewater ammonia concentrations were associated with greatest recreation intensity. Sandprawn abundance was similar across the recreation gradient and body condition was counter-intuitively greater in areas with maximum recreation, but with higher frequencies of embryonic aberrations and arrested development. These findings suggest different vulnerabilities of life-history stages of sandprawns to recreation, with embryonic stages being highly susceptible. We suggest that embryonic aberrations and developmental changes in endobenthic crustaceans may be sensitive bioindicators of recreation-induced changes in sedimentary systems.

Pervasive Microplastic Ingestion by Commercial Fish Species from a Natural Lagoon Environment

Microplastics have emerged as a significant global environmental concern in the recent decade. The aim of this study was to elucidate microplastic contamination of commercial fish species in a natural lagoon environment. Microplastic contamination was examined in the gastrointestinal tracts and gills of 157 commercial fish from 18 species with varying feeding habits in a vital and sensitive lagoon ecosystem, which connects to the Indian ocean. Microplastics were extracted using digestion, followed by stereomicroscopic inspection using Nile Red stain, and identified via μ-FTIR analysis. Over half of studied fishes ingested microplastics (54.14%). Filaments (50%) and blue items (43%) were the most commonly ingested. Of all the fish species, Eubleekeria splendens had the highest average concentration of microplastics in GIT (1.41 ± 2.52 items/g w.w. tissues), although no statistically significant difference in amount of ingested microplastics (items/g w.w. tissues) was observed among species. The highest concentrations of inhaled microplastics were recorded in Sillago vincenti (1.38 ± 1.30 items/g w.w. tissues). The majority of the extracted microplastics (33%) belonged in the size class 500–1500 μm with rayon, polyethylene terephthalate, and polypropylene as the primary polymers. This study found no correlation between microplastic ingestion and fish species and feeding habits, but a positive correlation with fish size was observed. These findings reveal widespread microplastic contamination in edible fish, posing potential risks to commercially important species due to increasing pollution in lagoon ecosystems.

Hypoxia extreme events in a changing climate: Machine learning methods and deterministic simulations for future scenarios development in the Venice Lagoon

Climate change pressures include the dissolved oxygen decline that in lagoon ecosystems can lead to hypoxia, i.e. low dissolved oxygen concentrations, which have consequences to ecosystem functioning including biogeochemical cycling from mild to severe disruption. The study investigates the potential of machine learning (ML) and deterministic models to predict future hypoxia events. Employing ML models, e.g. Random Forest and AdaBoost, past hypoxia events (2008–2019) in the Venice Lagoon were classified with an F1 score of around 0.83, based on water quality, meteorological, and spatio-temporal factors. Future scenarios (2050, 2100) were estimated by integrating hydrodynamic-biogeochemical and climate projections. Results suggest hypoxia events will increase from 3.5 % to 8.8 % by 2100, particularly in landward lagoon areas. Summer prediction foresee a rise from 118 events to 265 by 2100, with a longer hypoxia-prone season. This model is a valuable tool for developing hypoxia scenarios, aiding in identifying restoration hotspots for climate-threatened lagoons.

Tidal pumping and intertidal groundwater springs create pronounced spatiotemporal thermal variability in a coastal lagoon

AbstractIntertidal groundwater springs provide thermally stable, nutrient‐rich freshwater that causes fine‐scale variability in water temperature and salinity and promotes biodiversity in coastal estuaries and lagoons. In this study, we combined three thermal sensing techniques to elucidate summer water temperature patterns at the mouths of intertidal groundwater springs and the ambient coastal lagoon in Prince Edward Island, Canada. Thermal infrared imagery captured the spatiotemporal variability in relative temperatures of the lagoon channel and cold‐water plumes from the springs. Thermal anomalies due to the springs were detected at the surface throughout a tidal cycle, suggesting that the thermal plumes were buoyant. Fiber‐optic distributed temperature sensing paired with temperature loggers near the spring outlets recorded groundwater temperatures at low tide (~ 7°C) but ambient lagoon temperatures (up to 26°C) at high tide due to the vertical thermal gradient in the stratified water column. Calculated estuarine Richardson numbers throughout the study confirm intertidal spring buoyancy due to salinity differences. The fiber‐optic distributed temperature sensing results revealed pronounced variations in temperature as evidenced by spatial (3.7°C) and temporal (5.5°C) standard deviations over the cable length during the study and lower mean lagoon bed water temperatures at high tide (22.5°C) than low tide (24.3°C) due to heat advection from tidal pumping. Lagoon temperatures fluctuate at diurnal (solar) and semi‐diurnal (tidal) frequencies. The findings emphasize the efficacy of a multi‐technology approach to reveal fine‐scale and dynamic thermal processes that drive temperature patterns and habitat distribution in coastal lagoon ecosystems and highlight the thermal influence of intertidal springs.

Spatial Resilience of a Lagoon Ecosystem: The Case of the El Mellah Lagoon (Northeastern Algeria)

Spatial Resilience of a Lagoon Ecosystem: The Case of the El Mellah Lagoon (Northeastern Algeria)

Environmental DNA as Early Warning for Alien Species in Mediterranean Coastal Lagoons: Implications for Conservation and Management

Non-indigenous species (NIS) introduction notoriously threatens the Mediterranean Sea. In addition, Mediterranean coastal lagoons play a crucial role as nurseries for marine species, which new NIS arrivals can threaten. Therefore, monitoring and early warning of NIS presence is essential in preserving biodiversity. An innovative technique for rapid and accurate species identification and biodiversity screening is the application of environmental DNA (eDNA) metabarcoding. In this research, different Penaeidae (Arthropoda, Crustacea, Decapoda) NIS specimens were collected from a Mediterranean coastal lagoon after an early warning about a potentially invasive NIS arising from next-generation sequencing data. DNA barcoding of the DNA extracted from tissue samples and amplified with specifically designed primer pairs led to the recognition of Penaeus aztecus in this NATURA 2000 protected ecosystem for the first time. DNA barcoding from DNA isolated from the water where the living specimens were stored further validated the possibility of identifying P. aztecus starting from eDNA. This approach demonstrated the validity of environmental DNA analysis in the early screening of potentially invasive NIS presence in Mediterranean protected areas and ecosystems. This work describes an applicative example of the efficacy in improving the biomonitoring of lagoon ecosystems using molecular tools and it represents a guideline for the validation of eDNA metabarcoding data for the presence of potentially invasive species.

Microplastics in a lagoon ecosystem of the Nicaraguan humid tropics and their impact on Crassostrea rhizophorae populations

Microplastics in a lagoon ecosystem of the Nicaraguan humid tropics and their impact on Crassostrea rhizophorae populations

Seagrasses on the move: Tracing the multi-decadal species distribution trends in lagoon meadows using Landsat imagery

Seagrass meadows play a vital role for lagoon ecosystems and their biota, sustaining multiple ecosystem services. Their distribution and functioning are closely tied to the environmental pressures induced by global changes. Long-term monitoring of seagrass species and communities is, hence, important to depict their response to past and future scenarios. The availability of long term open-access satellite data offers a new remote sensing perspective for monitoring seagrass communities dynamics in shallow waters, especially when combined with machine learning algorithms. In this study, seasonal multispectral images (from 1999 to 2019) were collected from Landsat 5 Thematic Mapper and 8 Operational Land Imager satellites to map the seagrass meadows, at the community and species levels, within the vast Grado and Marano lagoon (Northeast Italy) using a Random Forest (RF) algorithm. RF models were calculated using an extensive field training dataset collected in 2010 (n = 426) and reached an overall accuracy of 0.92 and 0.76 for the classification at the community and species levels, respectively. The change detection analysis revealed an increase of 14.16 km2 (+ 39%) of the whole seagrass community cover over the period, at a rate of 1.59 km2year−1. Despite the coarse spatial resolution (30 m) of the Landsat's images, the classification of seagrasses at species level achieved a good overall accuracy (0.76), evidencing Nanozostera noltei as the species with the highest cover increase (+13.87 km2 over the time period). The observed expansion is likely caused by an increase of the sea water influence that is radically modifying Adriatic brackish water bodies, emphasizing the connection between the ongoing environmental changes and the rapid responses of seagrass meadows.

Hydro-ecological modelling of a hypersaline lagoon ecosystem (Pulicat) in Southeast coast of India

Climate change impacts the coastal lagoons and can affect various species reproductive cycles, feeding habits, and survival. Due to natural factors, the ecosystem habitat at Pulicat Lagoon on the east coast of India is under severe stress. This study assesses the ecosystem using a numerical model and field-collected physical, chemical, biological, and meteorological data for 2018 and 2019. A coupled hydro-ecological model was used to analyze circulation features, biological and chemical interactions, and transformation processes. The study indicates that high abnormalities in the lagoon ecosystem are caused by less exchange of fresh/coastal water from river sources and sea mouths due to less rainfall during the study period. The model output depicts the salinity variation from 15 to 58 PSU in different seasons of 2018 and 2019. Furthermore, high concentrations of Chl-a ranged from 50 μg/L to 95 μg/L during the monsoon and post-monsoon seasons, triggering phytoplankton C (70–350 mg/m3) and zooplankton C (9–43 mg/m3) at the Lagoon, resulting in an algal bloom. The monsoonal shift of Chlorophyte (9.52%–9.68%), Cyanobacteria (13.22%–14.95%), Diatoms (66.08%–63.87%), and Dinoflagellates (11.18%–11.51%) is observed in the biological field, with Diatom showing the highest abundance (65%). As a result, appropriate scenario-based model studies were conducted to conserve and strengthen the ecosystem during such extreme events. The model studies suggest that widening the lagoon inlet (800m) with a depth of 5 m (3 km length) increases the optimal tidal exchange to the ecosystem. The model output demonstrates the optimal exchange that normalizes the salinity from 12 to 34 PSU from the inner Lagoon to the mouth region. This study will support environmental authorities in conserving the ecosystem through proper management adaptations.

Vulnerability of tidal morphologies to relative sea-level rise in the Venice Lagoon

The rise in sea level and land subsidence are seriously threatening the diversity of tidal morphologies that have made the Venice Lagoon such a distinctive landscape. Here, we assess the vulnerability of tidal morphologies to relative sea-level rise based on a new conceptual framework that accounts for both above- and below-sea-level zones, sedimentary architecture, and surface morphology. Around 80 % of the lagoon area will face moderate to severe vulnerability by 2050, doubling compared to the 1990s. While the subtidal zone may be relatively less threatened compared to past conditions, the drastic decline in intertidal morphologies is alarming. This contributes to the flattening and deepening of the lagoon topography and thus to the loss of lagoon landscape diversity, likely leading to a decrease in the ecosystem services the tidal morphologies provide. The interconnection of intertidal and subtidal morphologies is crucial for maintaining the overall health and functionality of the lagoon's ecosystem. Any disruption to one aspect can have ripple effects throughout the entire system.

Assessing the impact of the invasive ctenophore Mnemiopsis leidyi on artisanal fisheries in the Venice Lagoon: an interdisciplinary approach

AbstractThe sea walnut, Mnemiopsis leidyi, has invaded and expanded throughout the whole Mediterranean Sea basin. Large blooms were recorded also in the Venice Lagoon (Italy), an ecosystem rich with biodiversity which supports multiple services, including artisanal fishery production. To investigate M. leidyi impacts on lagoon artisanal fisheries, we combined fishers’ local ecological knowledge, fishery landing time series analysis, and field sampling. Firstly, we interviewed artisanal fishers to date the blooms of M. leidyi. Secondly, we analyzed long-term fishery landings records to detect whether changes in landings quantity and composition were related to the ctenophore invasion. Thirdly, we sampled catches of the lagoon fyke nets. This interdisciplinary approach overcame the weaknesses of single methodologies and allowed us to reconstruct the temporal phases of M. leidyi invasion in the Venice Lagoon. Moreover, our results indicate that the lagoon landings significantly declined with the blooms, paralleled by the increase of water temperature. Finally, we showed that the mechanical obstruction of the nets, caused by the massive ctenophore blooms, strongly impacts fishing activities. Our results are a first step in assessing the short and long-term impacts of this invasive species on lagoon ecosystems, including its socioeconomic consequences, whose better understanding is fundamental to inform mitigation and adaptation measures.

Boon and burden: economic performance and future perspectives of the Venice flood protection system

Sea-level rise (SLR) and flooding are among the climate change stressors challenging human society in the twenty-first century. Many coastal areas and cities are implementing innovative solutions to mitigate flood risks and enhance resilience. Venice has recently developed a system of storm surge mobile barriers, known as the MoSE (Modulo Sperimentale Elettromeccanico or Experimental Electromechanical Module). This study aims to investigate the economic viability of MoSE operations in light of the potential future evolution of SLR. To conduct a cost-benefit analysis, a system dynamics model is utilised to assess the impact of MoSE operations on economic and residential activities of Venice and its port. Simulations are conducted until the end of the century, considering two SLR scenarios. The results suggest that the economic benefits largely outweigh the combined costs of investment and foregone port revenues resulting from the MoSE closures. Nevertheless, the increasing number of closures due to SLR seriously challenges the viability of the infrastructure in the medium to long term. Even more importantly, very frequent closures will have serious impacts on the quality of the lagoon ecosystem. These findings suggest a revision and stronger integration of the city’s safeguarding strategies, including the increase of the MoSE closure level officially set at 110 cm, and other coordinated interventions, such as sewer system consolidation.

State of Surface and Vertical Salinity in Puttalam Lagoon during North-East Monsoon

Puttalam Lagoon which covers 226 km2 located in Sri Lanka‘s Northwest coast, plays an important role in aquaculture and lagoon capture fisheries. Kala oya and Mee oya are the major freshwater sources which empties into the Lagoon by eastern bank. Salinity variability is an important environmental variable in lagoon system that has an impact on aquaculture and aquatic resources. During the Northeast monsoon (NEM) in 2021, the spatial and vertical fluctuation of salinity in the lagoon was studied using SBE 19plus V2 CTD profiler. Field measurements show that the vertical salinity stratification in the lagoon was substantial during the study period. The lagoon has a significant spatial variability of salinity, ranging from 15 psu to 26 psu and Kala Oya river mouth has a salinity of 22 psu which impacted by freshwater and sea water circulation. The Salinity stratification in eastern section of the lagoon where the Kala Oya and Mee Oya streamflow reach is observed with surface salinity of 15 psu. During the NEM season, the average discharge of Kala Oya and Mee Oya to the lagoon was 10.8 m3/s and 9.4 m3/s, respectively, with a mean monthly precipitation of 48.89 mm. Fresh water from the Kala and Mee oya rivers flows into the lagoon during the season, while low evaporation and significant rainfall led the salinity to decline during the wet season, influencing the structure and function of lagoon ecosystems. The study reveals that a significant area of the lagoon is covered by the 20-30 psu salinity range, which is more appropriate for brackish water fisheries, particularly for shrimp and prawns during NEM. 
 Keywords: Salinity, CTD profiling, Northeast Monsoon, Freshwater

SPATIO-TEMPORAL DYNAMICS OF ARSENIC CONTAMINATION OF SEDIMENTS IN IVORIAN COASTAL LAGOONS: THE CASE OF THE ABY LAGOON SYSTEM (ABYNORTH, TENDO)

Arsenic present in various components of lagoon ecosystems. This study aims at characterizing its distribution and identifying the factors influencing its mobility and bioavailability. Sediment samples were collected, prepared, and analyzed according to standardized protocols. Arsenic concentrations, measured by ICP-MS, were subjected to statistical analyses (ANOVA, t-test, correlation, etc.). The results revealed significant variability in arsenic concentrations in the sediments of the studied lagoons, with averages ranging from 9.13 mg/g in Tanoe lagoon to 27.16 mg/g in the bays of Tendo lagoon. They also showed seasonal and spatial variations in arsenic contamination, linked to the hydrological, geological and anthropogenic conditions of each site. Significant correlations were found between arsenic concentrations and environmental parameters such as salinity, transparency, conductivity and pH. These results contribute to a better understanding of the processes governing arsenic dynamics in coastal lagoons and underline the importance of considering seasonal variations and environmental conditions in sediment contamination studies.

Subtropical coastal microbiome variations due to massive river runoff after a cyclonic event

BackgroundCoastal ecosystem variability at tropical latitudes is dependent on climatic conditions. During the wet, rainy season, extreme climatic events such as cyclones, precipitation, and winds can be intense over a short period and may have a significant impact on the entire land‒sea continuum. This study focused on the effect of river runoff across the southwest coral lagoon ecosystem of Grand Terre Island of New Caledonia (South Pacific) after a cyclonic event, which is considered a pulse disturbance at our study site. The variability of coastal microbiomes, studied by the metabarcoding of V4 18S (protists) and V4–V5 16S (bacteria) rDNA genes, after the cyclone passage was associated with key environmental parameters describing the runoff impact (salinity, organic matter proxies, terrestrial rock origin metals) and compared to community structures observed during the dry season.ResultsMicrobiome biodiversity patterns of the dry season were destructured because of the runoff impact, and land-origin taxa were observed in the coastal areas. After the rainy event, different daily community dynamics were observed locally, with specific microbial taxa explaining these variabilities. Plume dispersal modeling revealed the extent of low salinity areas up to the coral reef area (16 km offshore), but a rapid (< 6 days) recovery to typical steady conditions of the lagoon's hydrology was observed. Conversely, during the same time, some biological components (microbial communities, Chl a) and biogeochemical components (particulate nickel, terrigenous organic matter) of the ecosystem did not recover to values observed during the dry season conditions.ConclusionThe ecosystem resilience of subtropical ecosystems must be evaluated from a multidisciplinary, holistic perspective and over the long term. This allows evaluating the risk associated with a potential continued and long-term disequilibrium of the ecosystem, triggered by the change in the frequency and intensity of extreme climatic events in the era of planetary climatic changes.

“If the mangroves disappear, so will San Crisanto — that’s how big the risk is”: Wetlands of a Coastal Lagoon Ecosystem and Local Adaptation to Climate Change

The Yucatan coast (Mexico) contains Ramsar sites of socioecological importance, but also faces problems, such as hurricanes, that increase its vulnerability. The frequency and magnitude of these threats increased, partly due to climate change, necessitating strengthened local adaptation strategies that incorporate the socioecological context and needs of wetland inhabitants. Thus, this study’s objective was to analyze responses to climate change by members of the port town San Crisanto (Yucatan) to learn about their perceptions and the actions they take when faced with hurricanes and their impacts. The study used a qualitative phenomenological methodology, working with 23 participants who witnessed three intense hydrometeorological events. As an ejido (unit of communal land tenure) in possession of land and resources, its members maintain the mangroves and manage them as a strategy of Ecosystem-based Adaptation (EbA). They support their actions with local socioecological knowledge of their territory and place-based attachment to the lagoon ecosystem that provides their livelihoods, but there also persist several practices requiring attention, such as filling floodable areas with waste, which damages the local population and ecosystem. We conclude that the ejido collective is relevant to ecosystem protection and recommend that EbA strategies be documented and strengthened in order to tend to the human population and the wetlands themselves in the face of climate change.

Sediment and Water physicochemical characterization of Marchica Lagoon (Oriental Rif, Morocco)

This study primarily focuses on the environmental assessment of the Marchica lagoon ecosystem. The objective of this research was to determine the ecological effects associated with the development, especially the opening of a new inlet, of the Marchica lagoon on the physicochemical parameters of its liquid phase, geochemical characteristics, as well as the distribution and content of sedimentary substrates. Two sampling campaigns were conducted in February 2023 and May 2023 within the Marchica lagoon to perform a detailed characterization of water physicochemical parameters, including temperature, pH, salinity, turbidity, dissolved oxygen, and chlorophyll. Additionally, a sedimentological and geochemical analysis of collected sediment samples was performed. The results highlight significant variations in these parameters, both in terms of location and temporal variations. Results of the sedimentological and geochemical study of the sediments are also included for a comprehensive understanding of the impact of management development on the lagoon's ecosystem.

SWOT analysis of the integrated coastal zone management (ICZM) in Marchica Lagoon Ecosystem, Morocco

This study consists to conduct an environmental SWOT analysis to assess Marchica lagoon and its watershed within the framework of Integrated Coastal Zone Management (ICZM). Recognized as a Ramsar site since 2005, the lagoon is located on the eastern Mediterranean coast of Morocco and offers a variety of ecosystem services. In response to substantial anthropogenic stress, the Moroccan government initiated a restoration plan since 2010 aimed at safeguarding these ecosystem services. Our analysis reveals that, despite restoration efforts, the lagoon is still adversely impacted by its watershed, including the discharge of wastewater, sometimes untreated. A significant environmental limitation identified is the inadequate integration of the “watershed-lagoon” spatial dimension in the lagoon’s management. Consequently, we recommend for the implementation of restoration measures upstream, especially in regions that exert influence on the lagoon. These actions are crucial to ensuring compliance with the spatial integration principles of the ICZM Protocol under the Barcelona Convention, promoting a more holistic and effective approach to ecosystem management.

A multibiomarker approach in clams (Ruditapes philippinarum) for a toxicological evaluation of dredged sediments

The Lagoon of Venice is often dredged for channel maintenance. To avoid harmful consequences to the ecosystem, a proper disposal of bottom sediments requires a preliminary evaluation of its potential toxicity before excavation. Here we evaluated the effects of polluted sediments on clams (Ruditapes philippinarum) using a multibiomarker approach. Bivalves were exposed for 3 and 14 days to five sediment samples collected along a navigation canal between Venice historical centre and the industrial area of Porto Marghera. Immunological, antioxidant, detoxification, and neurotoxicity biomarkers were analysed in haemolymph, gill, and digestive gland. As a control, sediment collected far from pollution sources was used. Two experiments were performed to assess potential seasonal/gametogenic influence in clam sensitivity. A different response of clam biomarkers was observed during the two experiments and among sampling sites. Clams’ digestive gland resulted to be the most sensitive tissue analysed showing significant differences among sites in all biomarkers analysed. Greater differences were present due to seasonality rather than exposure. The concentrations of metals and organic pollutants increased from the city centre to the industrial area, highlighting the influence that industrial activities had on the lagoon ecosystem. However, bioaccumulation in clams did not follow the same clear pattern, suggesting low bioavailability of compounds due to relatively high organic matter content. Biomarkers modulation was mainly driven by metals, both present in sediments and bioaccumulated. In comparison, effects of organic pollutants on the biomarkers tested were negligible. Other sources of contamination not investigated (e.g. pesticides) were suggested by neurotoxicity biomarkers alteration.