Lagoon Ecosystem Research Articles

SEASONAL CHANGES OF TOTAL MERCURY IN A MANGROVE LAGOON ECOSYSTEM

In order to understand the variation of total mercury (THg) in a tropical mangrove lagoon ecosystem. THg concentration was seasonally analysed in the biota and surface sediments from Setiu lagoon, Terengganu, Malaysia. THg in sediments showed spatially the similar trend with higher concentrations in dry season compared to the rainy season, whereas most of the biota was found the opposite trend between seasons. Increased rainfall during the rainy season may be the main factor enhancing the bioavailability of THg to biota. Fishes are recorded the highest THg accumulation compared to other groups. However, the THg accumulation in carnivorous fishes suggests the need for a long-term THg monitoring programme in the mangrove lagoon.

Economic assessment of the ecosystemic recreation service of the lake of Chacas - Juliaca

The objective was to estimate the economic benefits of the eco-systemic resources of the Chacas-Juliaca lagoon, the contingent valuation method was applied based on the declared preferences of the users of the lagoon, these data were introduced in a logit econometric model, a recreational service, determining a willingness to pay. The results show an entrance fee of S /. 38 that users are willing to pay, this availability depends on social and economic variables, such as income and the degree of academic education. These benefits will serve to recover the lagoon, allowing to create a fund that allows to conserve and protect the natural resources of the lagoon, currently there is a biotic and abiotic degradation due to the contamination of activities such as fishing and agriculture. Self-sustaining financing is required to conserve this natural resource, preventing future deterioration of the lagoon's ecosystem, allowing it to conserve its natural resources.

Assessment of the heavy metal sources and concentrations in the Nador Lagoon sediment, Northeast-Morocco

This study investigates the heavy metals (HM) and sulfurs concentration, enrichment level and potential sources in the bottom sediments of Nador lagoon, North-East Morocco. 50 samples of sediments from Nador lagoon heavy metals were analyzed by ICP-MS, while their spatial distribution and source identification were evaluated by Enrichment Factor (EF), QGis Inverse Distances Weighted (IDW) interpolation models, multivariate statistical techniques (Principal Component Analysis - Agglomerative Hierarchical Clustering - Pearson correlation matrix), Positive matrix factorization (PMF model) and grain size/organic matter analysis. The average heavy metal concentrations in the sediments are in the decreasing order: Sr > Ba > V > Zr > Zn > Cr > Rb > La > Cu > Pb > Ni > Ce > Nd > Co > Sc > Nb > Ga > Th > Y > Hf, and the Sulfurs. The results showed that the average concentrations of the S, Sr, Pb, and Nd in bottom sediments were higher than their background contents. The EF values demonstrated that HM contents were enriched by anthropogenic activities, especially for Sr and S, and secondly for Th, V, Ce, Nd, and Pb. The potential HM and sulfurs identified sources showed that: 1) Ga, Y, Hf, Nb, Rb, Sc, Zr, Nb, Co, Zn, Th, Ni, V, Ba, Cr, and Cu were derived industrial activities related to stealing and mining; 2) Wastewater treatment station and lagoon watershed were the main sources of Sr in the lagoon; 3) Zn, Cu, and Pb also linked to sulfurs, mostly origin from agriculture inputs and mining activities; 4) Ce, Cr, and Ni linked to sulfurs, mainly origin form metallurgical activities and solid wastes. The results suggest that heavy metal concentrations were significantly affected anthropogenic activities. Severe enrichment of Sr was found in the lagoon ecosystem with no correlation with carbonates, with four sources of heavy metals apportioned by Geostatistics and Positive matrix factorization. Solid waste, water waste and industrial activities were the main anthropogenic source. Lutite fraction and organic matter show a high accord with heavy metals concentration distribution.

SOME FEATURES OF THE SPECIES, SPATIAL AND TROPHIC STRUCTURE OF SUBLITTORAL AND LOWER LITTORAL MACROBENTHOS COMMUNITIES IN COASTAL LAGOON ECOSYSTEMS (KANDALAKSHA BAY, WHITE SEA)

The species composition, diversity, spatial and trophic structure of macrobenthic communities of the sublitoral and lower littoral zones were studied in several lagoon ecosystems (Kandalaksha Bay, White Sea). Surveys detected 52 species of benthic invertebrates and 6 species of seaweeds and algae in the investigated ecosystems. In the sublittoral zone, the greatest species diversity, total density and biomass of species populations were found in the lagoon least closed off from the sea, located at the exit from Kislaya Inlets’ head, where marine less euryhaline species were found more. The smallest species diversity was found in the most fenced and silted lagoons of the Nikolskaya Inlet and Zelyoniy Cape, where brackish water and marine euryhaline species prevailed. An intermediate position was occupied by the lagoon of Yermolinskaya Inlet and the lagoon near Lake Yershovskoe. In the littoral zone, as opposed to the sublittoral, common indicators of the macrobenthos community structure (total density, biomass, and less so the species diversity) increased from less regulated and open ecosystems to more enclosed ones. The exception was the lagoon of Nikolskaya Inlet, where significant overregulation and siltation led to a significant reduction in species diversity, total density and, especially, biomass of the macrobentos community. The trophic structure of macrobenthic communities of the studied lagoon ecosystems is characterized by a similar structure – the group of collector detritivores prevailed in the sublittoral zone, with an upward tendency from more open lagoons to lagoons sheltered off from the sea. In the lower littoral zone, which is more exposed to tidal impact, there was a greater amount of immobile sestonivores (Mytilus edulis), as well as scraper grazers (Littorina littorea) with the group of immobile sestonivores (M. edulis) tending to increase towards lagoons that are moderately sheltered off from the sea (the lagoon near Lake Yershovskoe lake and the lagoon of Yermolinskaya Inlet).

Spatial and seasonal distribution of Ostracoda in a lagoonal environment along the northeastern coast of India: Implications to assess coastal ecology and paleoenvironment

Variable seasonal interaction of both fresh and marine waters in lagoon ecosystems generally creates salinity gradients, which significantly impact the microhabitat of the benthos. This study assessed the spatial-seasonal abundance and diversity of ostracods along the salinity gradient of Chilika Lagoon (India) by seasonally collecting substrate sediment from twenty-two fixed stations along with the environmental parameters of lagoon-bottom water in Asia's largest brackish water lagoon. The samples were analyzed for living and dead ostracod species abundance, diversity and correlated with environmental parameters. The river mouth proximal region having sandy silt substrate under low energy conditions and high total organic carbon, had a higher abundance of low salinity tolerant ostracod species. The interior region of the lagoon showed a high abundance and diversity of variable salinity tolerant brackish water species, with a high proportion of dead specimens. In the region proximal to the sea mouth that is influenced by high energy conditions and sandy substrate, ostracod abundance and diversity are low, and only a few very high salinity tolerant ostracod species are found. Canonical correspondence analysis in addition to environmental preferences of living ostracod species and articulated valve abundance suggest environment-specific ostracod assemblages, consistent with the traditional use of ostracod species as a proxy to reconstruct paleo coastal ecology and paleoenvironment.

Empang Parit as Silvofishery Model to Support Conserving Mangrove and Increasing Economic Benefit of Social Community

Mangrove, estuary and lagoon ecosystem can be used as the aquatic organism habitat. These ecosystems also have good suitability to support activity of silvofishery system. Empang parit as a model of silvofishery using the integrating between the conservation activity of mangrove and aquatic ecosystem with increasing of benefit income for fisherman. This research aimed to analyze the model and pattern of empang parit, environment factor of empang parit and benefit cost analysis of empang parit. The research used vegetation analysis, water quality analysis, cash flow analysis, satellite image analysis, and geographical information analysis. The research explained that empang parit required water temperatur between 29 – 32.6oC, water brightnes between 30 – 60 cm, water salinity between 15 -32 ppt, pH between 7 – 81 and dissolve oxygen between 3.9 – 8.3 mg/L.The empang parit also need Bruguiera gymnorrhiza, Heritiera littoralis and Excoecaria agallocha, Rhizophora mucronata and Rhizophora apiculate to cover empang parit system. And empang parit gave postive economic value based on value of NPV between 2.754.703–3.871.542 IDR, IRR between 21–48 and R/C between 2.26–2.32.Keywords : Empang parit; silvofishery system; economic valuation; water quality; mangrove coverage

Resisting the Tourist Gaze. Art Activism Against Cruise Ship Extractivism in the Venice Lagoon

The essay situates Venice’s struggles against the cruise ship industry within a larger framework of resistance against planetary extractive capitalism, emphasising the role of local art-activist initiatives in denouncing the social and the ecological degradation caused by the cruise ship presence in Venice. In the first part, the concept of extractive tourism is introduced and analysed in relation to the case of Venice and the cruise companies’ economic model. The operations and infrastructure of cruise tourism produce extractive relations that entangle and exploit tourists, local communities and the natural environment. The Author examines how mass tourism has aggravated the environmental and social issues of the city of Venice and its lagoon. In the second part, the essay presents a number of artistic projects, specifically by visual artists Eleonora Sovrani, Gli Impresari, Banksy, and Elena Mazzi. These artworks can help us visualise the failures of the current urban development model of the tourist economy, while also exposing the nefarious effects of extractive capitalism on the well-being of the lagoon ecosystem and the human and non-human subjects cohabiting in it.

Temporal changes in water quality index of polluted lagoon ecosystems: a case study on the Küçükçekmece Lagoon.

For lagoon ecosystems, it is crucial to conduct long-term monitoring of the water quality parameters and predict their potential effects. This study aimed to analyse the changes in the water quality index (WQI) profile of the Küçükçekmece Lagoon in Istanbul, Turkey, which has been facing ecological problems, and determine the increased stress in aquatic biota due to different pollutants. To begin, the sampling data were obtained from the Küçükçekmece Lagoon throughout a 13-month period in 2018-2019. The estimated WQI values were compared to studies conducted in the same study area within the last 20years. Then, the relationship between the acute toxicity of surface waters, which is the recommended parameter for analyses in this field, and the WQI was determined. Although the water class has generally been defined as 'good quality' (WQI = 86), the study found it to be 'very poor quality' (WQI = 112 and 97, respectively) with bloom events and toxicity effects in spring and autumn. When compared with the WQIs calculated from the last 20years, a significant improvement in water quality at station L1 (decreased from WQI = 288 to WQI = 161) and a deterioration at station L2 (increased from WQI = 71 to WQI = 100) were observed. The acute toxicity and water quality classes were highly positively correlated (r = 0.773; p < 0.01). The method, used for the first time in this area, was able to interpret the acute toxicity of lagoon surface waters and WQI data. Furthermore, the use of this method was recommended for rapid analysis of the increased stress in aquatic biota.

Current status and unique attributes of Indian Chilika buffalo for adaptation to brackish water ecology.

Chilika buffalo is native to the Eastern coast of India and well adapted to the largest coastal brackish water lagoon of Asia, Chilika Lake. We present here a report on the Chilika buffalo breed emphasizing the conservational urgency based on unique biochemical and molecular evidence related to liver and kidney functions while comparing it with tropically adapted other water buffalo breeds (Bubalus bubalis) of India. It is found that the Chilika buffalo breed has a better ability to withstand a long dehydration period as evident from its better glomerular filtration and higher expression of the ion transport channel. Mitochondrial D-loop sequencing results have shown these buffaloes being closer to swamp-type buffaloes of Bangladesh and northeast India and represent a unique "hybrid zone" on the eastern coast of India. Conservation of such uniquely adapted germplasm is crucial owing to the current global trend, where the introduction of exotic breeds has negatively impact "sui-generis" germplasm and they require higher managerial resource consumption for maintaining higher productivity. Further, the introduction of unconventional fisheries activities has proved detrimental to the lagoon ecosystem, potentially causing more threat to the buffalo's population.

Identifying fish assemblages in tropical lagoon ecosystem: First record from Luang Island, South-west Maluku Indonesia

The aim of this study was to record demersal species from lagoon in Luang Island, a small and remote island in Maluku, Indonesia. Quantitative and qualitative methods were employed with the assistance of the local fishers using 4 different methods of fishing: gillnets, spear guns, traps, and handlines. Fisher knowledge informed fish abundance and frequency of occurrence. A total of 348 individual fish distributed across 53 species were recorded from the catch of 4 gear types. Bray-Curtis similarity scores of fish assemblages at different habitats was ranged from 7.19% to 10.35%. The nMDS bi-plot visualized a distinct dimension with which to allocate 3 habitats separately from the sand-seagrass habitat. Significant similarity of species at 4 different habitats (ANOSIM R2 = 0.124, P = 0.002) suggested that the habitat parameter was not able to predict different communities of fish. This paper is the first contribution on the composition of lagoon ichthyofaunal in Southwest Maluku Regency. Wise attitude towards marine resource exploitation such as traditional conservation, less fishing pressure and marine culture will maintain the healthy ichthyofaunal assemblages in a tropical lagoon ecosystem.

Seasonality of dissolved organic matter in lagoon ecosystems along the Alaska Beaufort Sea coast

AbstractSeasonal variations in dissolved organic matter (DOM) fluxes from land to sea have been well documented in the Arctic, yet remarkably little is known about how DOM varies seasonally within Arctic coastal waters. This is particularly true for shallow inshore environments. Here we document seasonality of DOM in lagoons along the eastern Alaska Beaufort Sea coast during the spring ice break‐up (June), summer open‐water (August), and late winter ice‐covered (April) periods. We measured dissolved organic carbon (DOC) concentrations, C:N ratios, and chromophoric DOM (CDOM) characteristics (SUVA254 and S275–295). On average, lagoon DOC was highest during spring (~200 μM) and lowest during winter (~120 μM). C:N and SUVA254 also differed markedly between spring (C:N ~ 28; SUVA254 ~ 3.5 L mg C−1 m−1) and winter (C:N ~ 16; SUVA254 ~ 2.2 L mg C−1 m−1). Average S275–295 values (~14–17 × 10−3 nm−1) were not significantly different among seasons, but variability in S275–295 was much lower in spring. This was attributed to terrestrial runoff based on its relatively uniform composition during the spring freshet. Seasonal variations in lagoon DOM were broadly correlated with variations in salinity (i.e., lagoon water transitioned from largely fresh in spring to hypersaline in winter), but a mixing analysis revealed strong evidence of processing and net DOC generation in summer. We also found evidence of DOC processing and build‐up under the ice over the winter. This baseline understanding of DOM seasonality in Arctic lagoons is essential for evaluating climate‐linked impacts on Arctic coastal ecosystems and broader feedbacks associated with carbon cycling.

The application of game theory-based machine learning modelling to assess climate variability effects on the sensitivity of lagoon ecosystem parameters

The extent of changes at the ecosystem level due to external dynamics from year to year of meteorological conditions is one of the basic determinants of climate change. The object of the study is the sensitivity of a set of environmental and planktonic factors shaping the ecosystem of a temperate shallow lagoon (the Vistula Lagoon, South Baltic) to weather fluctuations from year to year. The specific question concerned the short-term advantage of the sequence of environmental changes related to the impact of wind or those caused by the air temperature. The average speed in the prevailing westerly winds in the first summer research season was 3.05 m/s, while in the second it was 3.84 m/s. Simultaneously, the air temperature changed on average from 16.8 to 17.3 °C. The accuracy of the division of the two-year data set of ecosystemic parameters into the first colder and less windy and the second, warmer and windier summer was analyzed. For this purpose, several machine learning models were used. Next, the model with the highest accuracy was selected for the explanatory modelling based on game theory metrics Shapley Value. The analysis based on the interactions among ecological factors shows that the dynamics of the climate on a year-to-year scale can bring significantly more environmental changes in the shallow lagoon by an increase in wind speed rather than by an increase in air temperature. More windy weather in the summer in the subsequent year caused higher wind action, suspended solids, silicates and diatoms concentration. Simultaneously, the same conditions resulted in lower concentrations of dissolved organic carbon and nitrogen forms in water, accompanied by a reduction of Cyanobacteria biomass. The procedure presented in the study can be used for environmental prognostics of the environmental effects of climate change.

Relict inland mangrove ecosystem reveals Last Interglacial sea levels

Climatic oscillations during the Pleistocene played a major role in shaping the spatial distribution and demographic dynamics of Earth's biota, including our own species. The Last Interglacial (LIG) or Eemian Period (ca. 130 to 115 thousand years B.P.) was particularly influential because this period of peak warmth led to the retreat of all ice sheets with concomitant changes in global sea level. The impact of these strong environmental changes on the spatial distribution of marine and terrestrial ecosystems was severe as revealed by fossil data and paleogeographic modeling. Here, we report the occurrence of an extant, inland mangrove ecosystem and demonstrate that it is a relict of the LIG. This ecosystem is currently confined to the banks of the freshwater San Pedro Mártir River in the interior of the Mexico-Guatemala El Petén rainforests, 170 km away from the nearest ocean coast but showing the plant composition and physiognomy typical of a coastal lagoon ecosystem. Integrating genomic, geologic, and floristic data with sea level modeling, we present evidence that this inland ecosystem reached its current location during the LIG and has persisted there in isolation ever since the oceans receded during the Wisconsin glaciation. Our study provides a snapshot of the Pleistocene peak warmth and reveals biotic evidence that sea levels substantially influenced landscapes and species ranges in the tropics during this period.

Köyceğiz-Dalyan Lagün Ekosistemi Kefal Populasyonlarının Büyüme Performans İndeksleri

As it is common in tropical and temperate zones, mullet species constitute the most important fish species caught along the coast and estuaries of Turkey. In terms of ecology, tourism and and fish productivity (52 kg/ha), Koycegiz-Dalyan Lagoon Ecosystem (KDLES) is the most important lagoon, with a 5500 ha surface area, is the Mediterranean Coast of Turkey. In the dalyan (barrier fish trap) systems; approximately 225 tons (80-405 tons) of mullets are caught to obtain 5 tons of dried fish eggs per year. Seventy percent of fish production in the lagoon is composed of mullets. The mullet samples were collected monthly between October 1992 and September 1994 from eight stations (one of them is a marine station) by trammel nets. The ages were determined using by scales anda ge composition varied form 0 to 6 ages. Species composition of 1159 sampled individuals were proportionally determined as Mugil cephalus 45%, Liza aurata 35%, Liza saliens 14%, Liza ramada 12%, Chelon labrasus 6%. The growth performance indices calculated from von Bertalanffy growth parameters using by all individuals for the M. cephalus, L. aurata, L. saliens, L. ramada and C. labrasus were determined as 2.957, 2.866, 2.692 and 2.719, respectively. The highest growth performance index was calculated for M. cephalus. The growth performance indeces of mullet species in Köyceğiz-Dalyan Lagoon Ecosystem were found around the world averages.

Sea-level rise in Venice: historic and future trends (review article)

Abstract. The city of Venice and the surrounding lagoonal ecosystem are highly vulnerable to variations in relative sea level. In the past ∼150 years, this was characterized by an average rate of relative sea-level rise of about 2.5 mm/year resulting from the combined contributions of vertical land movement and sea-level rise. This literature review reassesses and synthesizes the progress achieved in quantification, understanding and prediction of the individual contributions to local relative sea level, with a focus on the most recent studies. Subsidence contributed to about half of the historical relative sea-level rise in Venice. The current best estimate of the average rate of sea-level rise during the observational period from 1872 to 2019 based on tide-gauge data after removal of subsidence effects is 1.23 ± 0.13 mm/year. A higher – but more uncertain – rate of sea-level rise is observed for more recent years. Between 1993 and 2019, an average change of about +2.76 ± 1.75 mm/year is estimated from tide-gauge data after removal of subsidence. Unfortunately, satellite altimetry does not provide reliable sea-level data within the Venice Lagoon. Local sea-level changes in Venice closely depend on sea-level variations in the Adriatic Sea, which in turn are linked to sea-level variations in the Mediterranean Sea. Water mass exchange through the Strait of Gibraltar and its drivers currently constitute a source of substantial uncertainty for estimating future deviations of the Mediterranean mean sea-level trend from the global-mean value. Regional atmospheric and oceanic processes will likely contribute significant interannual and interdecadal future variability in Venetian sea level with a magnitude comparable to that observed in the past. On the basis of regional projections of sea-level rise and an understanding of the local and regional processes affecting relative sea-level trends in Venice, the likely range of atmospherically corrected relative sea-level rise in Venice by 2100 ranges between 32 and 62 cm for the RCP2.6 scenario and between 58 and 110 cm for the RCP8.5 scenario, respectively. A plausible but unlikely high-end scenario linked to strong ice-sheet melting yields about 180 cm of relative sea-level rise in Venice by 2100. Projections of human-induced vertical land motions are currently not available, but historical evidence demonstrates that they have the potential to produce a significant contribution to the relative sea-level rise in Venice, exacerbating the hazard posed by climatically induced sea-level changes.

Distribution patterns and seasonal variations in phytoplankton communities of the hypersaline Pulicat lagoon, India.

Phytoplankton structure and patterns are key components to forecast the net result of the gain and loss process that outline the resilience of the lagoon ecosystem. In order to understand the phytoplankton community structure and its relationship with the environmental variables in the shallow hypersaline Pulicat lagoon, east coast of India, observations were carried out during August 2018-January 2019 covering the three seasons: premonsoon (PrM), monsoon (M), and postmonsoon (PoM). The salinity of the lagoon varied with a minimum of 12.1 for the M and a maximum of 81.65 during the PoM. The clustering analysis performed on the phytoplankton abundance data separated the lagoon into three sectors: north sector (NS), central sector (CS), and south sector (SS). A total of 59 taxa/morphotypes from four taxonomic classes (Bacillariophyceae, Chlorophyceae, Cyanophyceae, and Dinophyceae) were recorded during the study period. The class Bacillariophyceae was dominant in the lagoon both spatially and temporally by 44.06% with Chaetoceros borealis as dominant species. Presence of characteristic species like Dunaliella sp. was observed in the higher salinity, whereas Pediastrum duplex and Scenedesmus sp. were dominant in the freshwater influx areas. The individual-based functional approach allowed grouping these taxa into 11 functional entities based on the derived 4 functional trait values (cell size, trophic regime, mobility, and coloniality). Formation of algal blooms of Protoperidinium sp. (3.3×105ind L-1) and Odentella sp. (2.8×105ind L-1) was observed in the SS during PoM as a result of reduced water exchange in the lagoon. During the same period, toxin-producing strains like Anabaena sp. and Nostoc sp. of Cyanophyceae were also recorded. Correlating the three sectors of the lake (NS, CS, and SS), it is observed that the physical, chemical, and biological properties of the lake varied continuously depending on the season and freshwater availability. Seasonal nutrient stoichiometry played a significant role in regulating the community structure and distribution pattern of phytoplankton communities of the lagoon.

Comparative Cr and Mn speciation across a shore-to-reef gradient in lagoon sediments downstream of Cr-rich Ferralsols upon ultramafic rocks in New Caledonia

Ferralsols upon ultramafic rocks are among the most Cr-enriched soils at the Earth surface. Weathering and erosion of these soils represents a major source of Cr for coastal sediments downstream of ultramafic settings. Although Cr mainly occurs as Cr(III)-bearing chromite and Fe-(hydr)oxides in Ferralsols upon ultramafic rocks, several evidences of oxidized Cr(VI) in relation with Mn-oxides have been reported. Regarding the high solubility and toxicity of this latter Cr species, a thorough characterization of Cr and Mn crystal-chemistry in tropical sedimentary settings downstream of Ferralsols upon ultramafic rocks is needed to evaluate the potential threat towards the biodiversity of these coastal environments. In this study, we determined Cr and Mn speciation across a shore-to-reef gradient in lagoon sediments downstream of one of the largest lateritized ultramafic regolith in New Caledonia that contains up to 5 wt% Cr2O3. Chromium K-edge XANES data emphasized the absence of Cr(VI) and indicated a major hosting of Cr by chromite and clay minerals close to the shore, whereas Cr-bearing goethite dominated Cr speciation close to the reef. Manganese K-edge XANES data indicated a major hosting of Mn by clay minerals close to the shore, whereas Mn‑carbonates dominated Mn speciation close to the reef. The lack of Mn-oxides detection was considered to explain the absence of Cr(VI) in the studied sediments. This result thus suggests that, despite their shallow character that can favor occasional re-oxidation of the top-layer sediments upon re-suspension events, lagoon sedimentary settings downstream of Cr-rich Ferralsols upon ultramafic rocks appear rather favorable to Cr sequestration as the less mobile and less toxic Cr(III) form. However, the reverse trends observed from the shore to the reef between the chromite and goethite contributions to Cr speciation, as well as the decrease of the Cr/Ti ratio, suggest that a fraction of Cr could have been released towards the water column upon partial weathering of chromite to goethite during sediments transport across the shore-to-reef gradient. This latter point emphasizes the potential hazard that could still represent Cr for the exceptional biodiversity of tropical lagoon ecosystems downstream of Cr-rich Ferralsols, despite the absence of detectable Cr(VI). It thus calls for further studies aimed at better evaluating the stability of Cr(III)-bearing mineral phases upon early diagenesis in these shallow sedimentary settings.

Impacts of urbanization and land transitions on seagrass beds in tropical lagoon in central Vietnam

Socio-economic development activities have significantly affected biodiversity of seagrass beds in the coastal lagoon areas in central Vietnam. This study was carried out to investigate the major past and potential impacts on seagrass changes in Lang Co lagoon. In this study, historical satellite remote sensing data and GIS technology were used to evaluate the variation of seagrass beds during the period of 1998 to 2020. Bottom Reflectance Index (BRI) was employed with the correlation coefficient between the band pairs and the depth, which fluctuated between 0.76 and 0.90 with the bottom reflectance of the bands including bands 1, 2 and 3 ranging between 0.59 to 3.10, 0.66 to 2.35 and 0.45 to 1.95, respectively. Two coefficients were used to evaluate the accuracy of underwater objects including Kappa coefficient (K) and overall accuracy (OA) which ranged from 0.78 to 0.88 and 83.78 to 91.22, respectively. The classification results of terrestrial layers recorded Kappa coefficients and overall accuracies ranging from 0.76 to 0.90 and 85.35 to 99.27, respectively. The change in the area of seagrass beds and other land use types around Lang Co lagoon was studied during the period of 22 years. In the period of 1998–2004, seagrass was not clearly affected by socio-economic development activities, while the period of 2006–2012 witnessed significant impacts of socio-economic activities on seagrass beds. The period of 2014–2020 revealed the most apparent impacts of economic development on seagrass beds. The results of analyzing land use transitions indicated that while water, sand and artificial layers were stable over time; bare soil, forest and agricultural soil layers combined with plantation areas tended to change continuously over the years. The study results provide a scientific database for sustainable management of the Lang Co lagoon ecosystem in particular and coastal area in central Vietnam in general.

Fish species richness in the Terminos Lagoon: An occurrence data compilation of four sampling campaigns along a multidecadal series.

BackgroundHere we present an occurrence dataset that contributes to the knowledge of tropical fish distribution in coastal habitats from the Terminos Lagoon Flora and Fauna Protection Area, one of the largest lagoon ecosystems in the Gulf of Mexico. Fish are high biomass keystone species in the Terminos Lagoon which provide socio-economic and ecosystem services. An initiative in 1980 was carried out to systematically sample the fish community of Terminos Lagoon for an annual cycle; the effectiveness of its results led to replicate in the lagoon the same sampling design for three more campaigns in 1998, 2010 and 2016. Constituted as a Flora and Fauna Protection Area in 1994, the Terminos Lagoon has received many efforts to inventory its biodiversity, particularly on the fish community since the 70s; however, these studies did not have consistent survey protocols, nor the longevity of the present study, which was over four decades.New informationA total of 141 fish species, belonging to 90 genera, 49 families, 20 orders and two classes are presented in this study. Information on fish species occurrence data is provided corresponding to the Terminos Lagoon coastal ecosystem, southern Gulf of Mexico, assembled from four time periods at 1980, 1998, 2010 and 2016. The records form part of a consistently homogeneous database compilation, mostly derived from the research programme's sampled material on tropical fishery resources of the “Instituto de Ecologia, Pesquerias y Oceanografia del Golfo de Mexico (EPOMEX)”. The current dataset represents the first and most comprehensive online open-access source of information concerning the fish community occurring along and wide of the Terminos Lagoon ecosystem, with 1,249 data records and a total count of 48,717 organisms. Data are available through the Ocean Biodiversity Information System (OBIS).

How long the Mo.S.E. barriers will be effective in protecting all urban settlements within the Venice Lagoon? The wind setup constraint

The last IPCC report highlights that, along the present century, sea level rise driven by climate change will exacerbate the flooding frequency in coastal areas. Among others, the Venice Lagoon is one of the most vulnerable because of the presence of worldly famous historical urban settlements. To face this, a mobile flap gate system (Mo.S.E.) is nearly completed and has already raised across the lagoon inlets under testing phase to protect Venice from flooding. However, relative sea level rise and the wind setup effect during the closure of the lagoon, pose relevant management challenges such as timing and frequency to operate the barriers. In the present work, we first highlight some issues related to the management protocol currently adopted. We suggest a new strategy that optimizes the gate operation by identifying the shortest duration of closure that simultaneously prevents the flooding of all urban settlements within the lagoon. The new strategy is then used to estimate the Mo.S.E. management considering the last 20-year-long tidal record, but also for investigating different scenarios of relative sea level rise. The analysis we propose proves that the enhanced wind setup constraint will lead the Mo.S.E. system to fail in controlling all flood events starting from a relative sea level rise of +0.40 m. In addition, wind setup will increasingly often produce long and repeated closures, requiring further measures to combine flood protection, port and industrial activities and the conservation of the lagoon ecosystem.