Lagoon Estuarine System Research Articles

Variability of Dissolved Inorganic Carbon in the Most Extensive Karst Estuarine-Lagoon System of the Southern Gulf of Mexico

Coastal ecosystems with karstic geology have a unique characteristic where the dissolution of carbonate rocks can increase total alkalinity (TA) and dissolved inorganic carbon (DIC). This results in higher inorganic carbon budgets in coastal areas. One such ecosystem is the Terminos Lagoon, the most extensive tropical estuarine lagoon system in Mexico, located in the karstic aquifer of the Yucatan Peninsula and connected to the southern Gulf of Mexico (sGoM). We measured TA and DIC to evaluate the variability in Terminos Lagoon’s of the carbonate system. We also estimated pH, partial CO2 pressure (pCO2), and aragonite saturation (ΩAr) along two transects from the main lagoon tributaries (Palizada and Candelaria rivers) to the coastal zone during the dry and rainy seasons. During the dry season, TA and DIC concentrations were significantly higher (3092 ± 452 µmol kg-1 TA, 2943 ± 522 µmol kg-1 DIC) than during the rainy season (2533 ± 228 µmol kg−1 TA, 2492 ± 259 DIC µmol kg−1). Our calculations indicate that the rainy season pCO2 (2532 ± 2371 µatm) seems higher than in the dry season (1534 ± 1192 µatm). This leads to a reduction in pH (7.9 ± 0.3 to 7.8 ± 0.3). These significant changes indicate that rain increases the flow of unsaturated river water into the lagoon. The results of this work contribute toward a dissolved inorganic carbon variability baseline in the sGoM and can be helpful to Terminos Lagoon decision-makers.

Seasonal variations in residence time and water age in the Mundaú-Manguaba Estuarine Lagoon System, AL (Brazil)

The Characteristic Hydraulic Times (CHT), called Residence Time (RT) and Water Age (WA), were analyzed in the Mundaú-Manguaba Estuarine Lagoon System (MMELS – AL, Brazil), using the SisBaHiA® – Environmental Hydrodynamics Base System, for two scenarios: wet season, from May to July 2018; and dry season, from October to December 2018. The hydrodynamic modelings appropriately represented water level variations measured in the lagoons. The analysis of residual currents revealed how hydrodynamic circulation was affected by seasonal variations, and provided essential information to understand the results of the RT and WA simulations. This study deepened the knowledge regarding the RT of the water masses inside the lagoons, and reinforced how river discharges significantly influence their export, which resulted, considering the spatial scope, in much smaller RT in the wet season compared to the dry season. The WA analysis added new and significant knowledge about water renewal, from a different perspective, and as yet little-explored in the study region. Among the results obtained, the most relevant refer to the dry season, in which it was found that the “oldest” waters in the Mundaú L. occurred near the southeast region, while in the Manguaba L., in the vicinity of the central region. Both regions were confirmed as the places that present the most critical trophic state index in each lagoon, showing that WA is a CHT that indicates the regions most conducive to more critical trophic states.
 Keywords: Mundaú-Manguaba lagoons, residence time, water age.

Characterization of the organic matter produced by Atlantic Rainforest plants and its influence in the surface sediments deposited in a protected subtropical Estuarine–Lagoon system

The aim of the present study was to characterize the distribution and sources of terrigenous organic matter (OM) in surface sediments of a subtropical estuarine–lagoon​ system surrounded by the Atlantic Rainforest. n-Alkanes and their isotopic composition were evaluated in 20 surface sediment samples, as well as in leaves from nine representative plant species collected from the Cananéia–Iguape Estuarine–Lagoon​ System (CIELS; Brazil). According to the calculated n-alkanes indices, the analyzed plants could be grouped as monocotyledonous (aquatic productivity index [Paq] > 0.1; carbon preference index [CPI] < 6), dicotyledonous (Paq < 0.1; CPI > 10), mangrove (average chain length [ACL23−33] < 29; ratio of n-C31 over n-C29 concentration [Norm31] < 0.1) and riparian (ACL23−33 > 29; Norm31 > 0.2) vegetation. δ13C n-alkane values were higher (> −26‰) in the C4 aquatic macrophyte analyzed (Spartina alterniflora), with intermediate values (−30 to −27‰) for the pteridophyte (Pteridium aquilinum), and lower values for the C3 species (< −31‰). In sediment, total n-alkanes, total organic carbon, and total nitrogen concentrations ranged from 510 to 10,000 ng g−1 in dry sediment, 0.15 to 6.37% and not detected to 0.74%, respectively, being governed by the mud composition. ACL23−33 and the Norm31 values ranged from 29.0 to 30.4 and 0.39 to 0.57, respectively. Paq and CPI values ranged from 0.06 to 0.25 and 4.2 to 6.6, respectively. These indexes showed that the main terrigenous OM source to CIELS sediment was the riparian vegetation, coming from the rivers that discharge into the system. The n-alkanes δ13C composition, ranging from −36.0 ± 0.0 to −24.8 ± 0.3‰, also showed contributions of macrophytes input to the deposited OM. The influence of mangrove trees is not dominant but increases in the CIELS eastern region, where this kind of vegetation is more developed.

Composition and spatial distribution of floating plastic debris along the estuarine ecocline of a subtropical coastal lagoon in the Western Atlantic

With the objective of characterizing the composition and spatial distribution of plastic fragments in a subtropical lagoon system, five sample areas affected by various anthropogenic impacts were chosen in the southern part of the Estuarine Lagoon System in Laguna, Santa Catarina, Brazil. The total density of the floating meso- and microplastics encountered was 7.32/m3, with the greatest density in the access channel and external area of the lagoon. Plastic filament was the most abundant and mainly comprised polyester (PET), polypropylene (PP) and polyethylene (PE) from 0.05 to 0.71 mm2. Fishing and urbanization were the main sources of the meso- and microplastics in the environment. This is the first study to evaluate contamination by meso- and microplastics in the southern part of the Estuarine Lagoon System and provides information about the nature and extent of contamination by plastics in this estuarine ecosystem.

A Trophic Model for a Periodically Closed Coastal Lagoon System in the Southern Mexican Pacific

Carretas-Pereyra is an estuarine lagoon system located in the southern Mexican Pacific coast. Its connection to the sea is intermittent, because the mouth of the system closes seasonally under natural conditions, but it is often opened artificially for artisanal fishery purposes. In order to know the degree of development, structure, and functioning of this system, under intermittent communication with the sea, a trophic model was built using software Ecopath. The model was composed of 32 functional groups: one for birds, one for crocodylians, 18 for fishes, 9 invertebrates, 2 plankton, and detritus. The pedigree index of the model was 0.62, which mean it is an acceptable model. The results are consistent with findings for lagoon systems with permanent connection to the sea. Some of the ecosystemic mechanisms probably used to face the abrupt changes induced by the opening of a sea inlet are: system omnivory, elevated overhead, efficient metabolism in phytoplankton, species replacement, and species adaptability to dominant environmental conditions. These elements provide stability to the ecosystem and help in its recovery. Detritus, zooplankton, and phytoplankton were important components for the resiliency of the system. In spite of the biological and environmental changes induced by the intermittent opening of an inlet, Carretas-Pereyra has the necessary elements to absorb the impacts and function adequately.

Primer registro de Branchiostoma californiense (Cephalochordata: Branchiostomatidae), en un sistema estuarino-lagunar de Chiapas, México

Background. Amphioxi (Cephalochordata), are a group of marine organisms of great relevance and interest in evolutionary studies, due to their phylogenetic position; inhabit the sandy bottoms of coastal waters around the world. Two species Branchiostoma elongatum and B. californiense are widely distributed throughout the Tropical Eastern Pacific. Objectives. The objective of this work is to document the occurrence of Branchios- toma californiense, in a lagoon-estuarine system from Chiapas, Mexico. Methods. The specimens were collected from the sandy bottom between 50 and 90 cm deep, using a stainless-steel sieve in the estuarine channel of the estuarine-lagoon system La Joya-Buenavista. Results. A total of 19 specimens of B. cali- forniense were collected. The specimens collected were juvenile stages less than 10mm in length (3.1-5.9 mm). Conclusions. These records indicate the first record of this species in the inland waters of Chiapas and represent the southernmost records of this species in the Mexican Pacific.

Abundance and demography of common bottlenose dolphins (Tursiops truncatus truncatus) in the Indian River Lagoon, Florida: A robust design capture-recapture analysis.

Common bottlenose dolphins (Tursiops truncatus truncatus) inhabiting the Indian River Lagoon (IRL) estuarine system along the east coast of Florida are impacted by anthropogenic activities and have had multiple unexplained mortality events. Given this, managers need precise estimates of demographic and abundance parameters. Mark-recapture photo-identification boat-based surveys following a Robust Design were used to estimate abundance, adult survival, and temporary emigration for the IRL estuarine system stock of bottlenose dolphins. Models allowed for temporary emigration and included a parameter (time since first capture) to assess evidence for transient individuals. Surveys (n = 135) were conducted along predetermined contour and transect lines throughout the entire IRL (2016–2017). The best fitting model allowed survival to differ for residents and transients and to vary by primary period, detection to vary by secondary session, and did not include temporary emigration. Dolphin abundance was estimated from 981 (95% CI: 882–1,090) in winter to 1,078 (95% CI: 968–1,201) in summer with a mean of 1,032 (95% CI: 969–1,098). Model averaged seasonal survival rate for marked residents was 0.85–1.00. Capture probability was 0.20 to 0.42 during secondary sessions and the transient rate was estimated as 0.06 to 0.07. This study is the first Robust Design mark-recapture survey to estimate abundance for IRL dolphins and provides population estimates to improve future survey design, as well as an example of data simulation to validate and optimize sampling design. Transients likely included individuals with home ranges extending north of the IRL requiring further assessment of stock delineation. Results were similar to prior abundance estimates from line-transect aerial surveys suggesting population stability over the last decade. These results will enable managers to evaluate the impact of fisheries-related takes and provide baseline demographic parameters for the IRL dolphin population which contends with anthropogenic impacts and repeated mortality events.

Atmospheric and sunglint correction for retrieving chlorophyll-a in a productive tropical estuarine-lagoon system using Sentinel-2 MSI imagery

Remote monitoring of chlorophyll-a (chla) has been widely used to evaluate the trophic state of inland and coastal waters, however, there is still much uncertainty in the algorithms applied in different optical water types. The influence of different atmospheric correction (AC) processors, which can also provide correction for sunglint and adjacency effects, on the retrieved chla is poorly understood. In this study, state-of-the-art atmospheric correction and chla algorithms are evaluated using Sentinel-2 MSI imagery in the Mundaú-Manguaba Estuarine-Lagoon System (MMELS), a productive tropical system that consists of two turbid lagoons of different optical water types (OWT). We compared the performance of six AC processors, with the addition of sunglint correction for two of them, with field measured water reflectance. There was difficulty in correcting for the atmospheric effects, especially for bands 2, 3 and 8A. Overall, C2X showed the best performance over MMELS, but with sunglint correction, ACOLITE and GRS provided the most consistent water reflectance (ρw). Sunglint correction might be essential for retrieving accurate ρw in most low-latitude water bodies. We also found that in Mundaú, the dense urban area surrounding it likely caused heavy adjacency effects in the satellite-retrieved reflectance, and thus correction for it is necessary. We also compared the performance of six chla algorithms recommended for the OWTs present in MMELS in addition to a widely applied and a global chla algorithm in retrieving this variable using both field and satellite reflectance, in this case corrected with the three best performing processors. For the in situ data, most algorithms performed well in Manguaba lagoon, while in Mundaú lagoon the semi-analytical NIR-red ratio (2SAR) algorithm was the most consistent model, and in both cases the locally calibrated algorithms outperformed the global algorithm. When retrieving chla with the satellite-derived ρw, considerably poorer results were produced, especially in Mundaú lagoon. The global algorithm was found to be especially sensitive to the atmospheric effects. We also found that the quality of AC provided by the algorithms is not a general predictor of the performance of the chla models, even when analysing individual bands separately, while the relationship between chla concentration and the ratio of bands used by most algorithms can be. Despite containing distinct water characteristics, chla can be modelled using a single algorithm, 2SAR, calibrated for MMELS as a whole, with r2 of 0.77 and nRMSE of 38.7%, and we consider that 2SAR has the potential to be a global algorithm for these OWTs, provided that it is recalibrated for a large dataset of satellite-derived BOA reflectance. We recommend that further studies explore the impacts of AC, sunglint and adjacency effects on the performance of chla algorithms, in order to delineate the most suitable combinations of AC + chla algorithms for the variable OWTs, in an effort to provide the basis for global-scale retrievals of this pigment using medium-resolution sensors such as MSI and OLI.

Variation in size distribution of juvenile pink shrimps Farfantepenaeus brasiliensis and F. paulensis in the estuarine-adjacent ocean area of Cananéia, south-eastern coast of Brazil

AbstractThe study characterized the structure of juveniles and sub-adults of Farfantepenaeus brasiliensis and F. paulensis in the Cananéia-Iguape estuarine lagoon system and its adjacent coastal area by evaluating the period of juvenile recruitment, sex ratio, growth, longevity, natural mortality, and development time until the late juvenile phase. Samples were collected from July 2012 to June 2014. Shrimps were identified by species and sex, and measured (carapace length – CL mm); 889 individuals of F. brasiliensis and 848 of F. paulensis were analysed. Females were more abundant than males for both species. The growth parameters of F. brasiliensis were: CL∞ = 45.5 mm, k = 1.8 year−1 for males and CL∞ = 55.2 mm, k = 1.6 year−1 for females; longevity of 2.52 years (males) and 2.88 years (females); and natural mortality of 1.71 (males) and 1.55 (females). For F. paulensis, the following values were observed: CL∞ = 40.7 mm, k = 2.3 year−1 for males and CL∞ = 56.5 mm, k = 1.9 year−1 for females; longevity of 2.04 years (males) and 2.37 years (females); and natural mortality of 2.39 (males) and 2.05 (females). The juvenile recruitment of both species peaked in January 2014. The development time until late juvenile phase was ~7 months (F. brasiliensis) and ~5 months (F. paulensis). Even though the highest abundance of juveniles did not occur in the closed season, fishing is forbidden in the estuarine area and the migration towards the adult population occurred close to or even during the closed season.

Interaction of Suspended Particulate Material with Cd2+ and Pb2+ in a Brazilian Lagoon Estuarine System

The suspended particulate material (SPM) present in waters has fundamental importance for a better understanding of environmental behaviors of aquatic pollutants. This work determined the physicochemical parameters (pH, temperature, conductivity, total organic carbon and metals concentration) in water samples from Mundau-Manguaba estuarine-lagoon system, Alagoas, Brazil. This work extracted and characterized the organic matter present in SPM in this estuary and studied the interaction of this organic matter with potentially toxic metals (Cd2+ and Pb2+). The results of the physical-chemical parameters evaluated showed influence of the tide and also of anthropic contributions close to the estuary. In fact, the lead concentrations determined (0.10-1.32 mg L-1) are well above that allowed by Brazilian legislation (< 0.010 mg L-1). The organic matter present in the SPM showed a high degree of humification being similar to the organic matter extracted from water and showed strong interaction by Pb2+ ions.

Active mechanisms controlling morphodynamics of a coastal barrier: Ilha Comprida, Brazil

Abstract The Cananeia-Iguape lagoon-estuarine system, where the Ilha Comprida barrier (IC) is located, is one of the most dynamic coastal areas on the southeastern Brazilian coast. IC island is a 63 km-long barrier and it is limited by the Icapara inlet to the north, and the Cananeia inlet to the south. This system has been affected by intense changes in its morphology since the opening of the Valo Grande artificial channel in 1852 A.D., connecting the nearby Ribeira de Iguape river to the Mar Pequeno lagoon. In this context of anthropogenic disturbance on the coastal systems, the objective of this study is to understand the active mechanisms, both natural and anthropogenic, controlling the morphological changes of the northeastern portion of the IC, from monthly as well as centenary timescales. We analyzed successional addition and erosion of beach ridges using a multi-temporal dataset obtained by Optically Stimulated Luminescence, aerial photos (1962 and 2000), satellite images (1980-2016) and GNSS surveys (2015-2017). The results were compared to climatic (rainfall and waves) data. Northeastward migration rates of the IC ranged from 15.5 m/y, on the GNSS surveys, to 154 m/y, calculated based on OSL rates. Changes on rates on the northeastward inlet migration barrier are related to anthropogenic interference, mainly the Valo Grande opening and climate changes. Sediment accumulation occurred mainly during the summer on the baymouth spits. This depositional scheme is consistent with the highest values of Ribeira de Iguape river flow and the low synergy of waves coming from the South. By contrast, the retrogradation of the coastline occurs in the winter, when the wave power is stronger than in the summer. This seasonal configuration is controlled both by the bidirectional longshore drift and by the fluvial discharge.

Design and implementation of a low-cost multiparameter probe to evaluate the temporal variations of water quality conditions on an estuarine lagoon system.

The measurement of physicochemical variables to infer water quality is important since they help determine the distribution and abundance of aquatic organisms or pollution-related problems. Recently, the development of low-cost probes is a suitable alternative for continuous monitoring of these variables rather than the use of expensive instruments. In this work, a low-cost multiparameter probe (LCMP) has been developed to monitor water quality in an estuary located in Northwestern Mexico during a 3-month period. The LCMP integrates different sensors to an Arduino Nano microcontroller allowing to measure electrical conductivity, dissolved oxygen, pH, salinity, water temperature, and tide level. Data files were stored in a data logger system consisting of a secure digital (SD) card module and a real-time clock module coupled to the Arduino microcontroller. To ensure continuous operation, the system was powered by four 3.7V, 10,000mAh rechargeable LiPo batteries. All LCMP components were encapsulated in a polyvinyl chloride pipe. The results show that the LCMP had a good agreement with a commercial-grade multiparameter probe and was able to monitor continuously in hourly time steps. Finally, the LCMP proved to be an alternative for the establishment of coastal observatories, which has been deficient due to limited funding.

Ecosystem-level carbon stocks and sequestration rates in mangroves in the Cananéia-Iguape lagoon estuarine system, southeastern Brazil

Mangroves fringe the coastlines of 54% of the world’s nations but convey ecosystem services, such as carbon sequestration, that span administrative boundaries. Despite their high carbon sequestration efficiency and long-term storage capacity, few countries have assembled detailed mangrove carbon inventories. For example, Brazil, which detains the second largest mangrove area in the world, still lacks a detailed inventory on its blue carbon resources, largely due to the scarcity of integrated ecosystem-level (that is, carbon stored in biomass and soil combined) carbon assessments. Here we combine published and unpublished data to derive an inventory on ecosystem-level carbon stocks and carbon sequestration rates in the Cananéia-Iguape lagoon estuarine system, southeastern Brazil. We find that mangroves in the study area have the largest per-unit-area ecosystem-level carbon stocks at 380 MgC ha−1 when compared to other Brazilian mangroves. Soil organic carbon stocks (top meter) account for 70% of this total. Annual carbon sequestration in mangrove soils and woody biomass combined with carbon fluxes via litterfall total 0.16 TgC yr−1. Degradation of mangrove ecosystems in this region could lead to CO2e emissions up to 1,395 MgCO2 ha−1 and reduce annual carbon sequestration in soil and biomass combined, and carbon flux via litterfall by 27 and 12 MgCO2 ha−1 yr−1, respectively. Our results provide coastal wetlands managers and scientists with novel information on mangrove carbon stocks and sequestration rates in the study area, which is useful to strengthen regional blue carbon and potential CO2e emission inventories. These estimates can also be used to establish performance measures to inform restoration targets as well as to serve as a baseline for comparison with current and future measurements of carbon stocks and fluxes in response to environmental change.

The influence of habitat on the spatio-temporal dynamics of fish assemblages in a lagoon-estuarine system of the Mexican Pacific

Fish assemblages change significantly with physical and chemical characteristics of water; however, their response to the variability of geomorphic habitats has been rarely evaluated in lagoon-estuarine in one of these systems of the Mexican Pacific. Spatio-temporal variation of fish assemblage structure was assessed for three habitats: lagoon, estuarine, channel and inlet. The hypothesis was that sheltered areas support comparatively higher richness and abundance of fish species, with more small-sized specimens than the most exposed areas. We found that the ichthyofauna differed significantly among habitats. Several species were smaller in the lagoon compared with the other habitats, suggesting a use of the lagoon as a nursery ground. Moreover, dominant species for the lagoon were rarely found or absent in the inlet, whereas others were found only present or with higher abundance in the inlet. Although seasonal differences in richness and composition were detected, the evidence of fish-habitat associations for many species was noticeable regardless of seasonality, probably due to a high percentage of resident species during the annual cycle. The lagoon supports a greater abundance and species richness, due to a more sheltered and structured habitat, evidencing habitat-driven segregation in fish assemblages, and an aspect that should be incorporated for management of coastal ecosystems.

Trophic dynamics in two South American estuaries encompassing industrial development and a biodiversity hotspot

Abstract Estuaries are critical to the life histories and development of many marine species, and support some of the most productive aquatic ecosystems. However, owing to their geographic accessibility, many estuaries face considerable anthropogenic threats, which can be exacerbated in developing nations. Understanding the ecological implications of anthropogenic activities as a precursor to dedicated conservation activities requires comprehensive assessments of baseline trophic relationships. This study addresses a shortfall in such information for two tropical, coastal ecosystems globally identified as priority areas for biodiversity conservation: the Paranaguá estuarine complex; and the Cananéia–Iguape estuarine lagoon system in southern Brazil. Ecological relationships were investigated through carbon and nitrogen stable isotope (δ13C and δ15N) determination in sediments, plant fragments and the muscle tissues of marine species occupying different trophic levels, including benthic invertebrates, ichthyofauna (Stellifer rastrifer, Paralonchurus brasiliensis, and Isopisthus parvipinnis), and delphinids (Sotalia guianensis and Pontoporia blainvillei). Isotope ratios facilitated distinguishing plant fragments, sediments (which were terrestrially influenced) and biota (predominantly marine influenced). However, despite variation among anthropogenic stressors, isotope ratios did not vary between the studied estuaries, implying similar impacts on trophic relationships which might reflect some inter‐estuary mixing. All ichthyofauna and the delphinids had similar generalist diets and shared the same trophic niche, which may reflect their consistent spatio‐temporal distributions and habitat patterns in the estuaries. The data illustrate the utility of isotopically characterizing biodiversity‐hotspot estuaries as a mechanism for rapidly assessing ecological relationships between key species and regional habitats. Such an approach can be used to evaluate ecological connectivity as a baseline for management and might be applied more broadly, embracing multiple regions as part of estuarine and coastal biome conservation efforts.

Environmental quality survey of an industrialized estuary and an Atlantic Forest Biosphere Reserve through a comparative appraisal of organic pollutants

An evaluation of the concentrations, bioavailability and sources of polycyclic aromatic hydrocarbons (PAHs) and persistent organic pollutants (POPs) was performed in the industrialized estuary of Santos-São Vicente and in the Cananéia-Iguape estuarine lagoon system, considered an Atlantic forest biosphere reserve, using different approaches. Semipermeable membrane devices (SPMDs) and bivalves (Crassostrea brasiliana) were deployed in both estuarine systems. Samples of water, suspended particulate material (PM), and sediments were also collected in these regions. The concentrations of PAHs in the water and in the PM from both estuarine systems were similar. In the sediment, the concentrations of PAHs and POPs were higher in the estuary of Santos-São Vicente than in the Cananéia-Iguape estuarine lagoon system. The accumulation of PAHs and POPs by the SPMD and C. brasiliana revealed that in both regions the bioavailability of contaminants was similar. Because of the hydrophobicity of the organic compounds, each matrix responded in a different manner to the source of the contaminants; C. brasiliana and sediment were primarily associated with 4–5 ring-PAHs that represent pyrolytic sources of hydrocarbons, whereas water and the SPMDs were correlated with the 2–3 ring-PAHs, which represent petrogenic sources. The PM produced an intermediated concentration among these compartments and was related to the concentration of POPs. Because no significant differences between the mean concentrations of contaminants in both studied regions were observed, anthropogenic effects currently impact the Cananéia-Iguape lagoon system, which was initially considered a pristine area.

Polychaete diversity patterns along an environmental gradient in Términos Lagoon, a tropical lagoon-estuarine system in the southern Gulf of Mexico

In this study we analyze the faunal changes along 2 transects (5 stations each) across Terminos Lagoon. We also examined the role of the environmental gradients in controlling the number and composition of the polychaete species, and evaluated the spatial changes of beta-diversity. In total, 299 individuals from 51 species and 24 families were identified. Salinity was the most important factor to define the environmental gradients ( r2 > 0.83), but the variations in the number of species did not follow this spatial trend. The highest species richness was found in the eastern transect (mean: 12 spp./station, 78.0 ind./0.1 m2), while the western transect harbored a less diverse (mean: 6 spp./station) and less abundant fauna (mean: 21.67 ind./0.1 m2). A high similarity value (0.70) was found between the transects, but the distribution of each species was very irregular, which in turn caused a decrease in the similarity among stations at each transect (< 0.54). Except among the middle stations of the western transect, where the nestedness component represented all the beta-diversity value (βnes: 0.80 to 0.88), the species turnover (βsim: 0.38-1.0) was the dominant factor of the total dissimilarity among the polychaetes inhabiting Terminos Lagoon.

Young does not mean unstable: a trophic model for an estuarine lagoon system in the Southern Mexican Pacific

A trophic model is presented for the coastal lagoon system Chantuto-Panzacola, Southern Pacific Mexico, with the aim of estimating its degree of development and functionality. Thirty-four functional groups (one for birds, one crocodilians, 20 fishes, nine zoobenthos, two plankton, one detritus) were analyzed using Ecopath’s approach, with species biomass, diet composition, and data of species’ production and consumption. Diet was examined from stomach contents for the 39 most abundant fish species, the rest being determined from literature. Detritus was the most important component of the ecosystem in terms of biomass and flows, whereas diverse groups of zoobenthos linked detritus to upper functional groups. Consumers’ trophic level fluctuated between 2.00 and 4.08, with crocodilians as top predators. The size of the system, in terms of matter flows, was 7,133 g m−2 year−1; this value was greater than those recorded in other estuarine systems. Chantuto-Panzacola has a short geological age and is in an intermediate development stage; however, its youth and immaturity are accompanied by attributes which confer stability and environmental health, such as high productivity, high omnivory, and a great reserve potential that the system uses to face disturbances (overhead). The quality of the model was relatively high with respect to others.

Anthropogenic Impacts on Biochemical Processes in a Tropical Estuarine Lagoon

Estuaries play an invaluable role in the transformation and cycling of materials as they move between land and sea; including anthropogenic materials. Increasingly, human land use is delivering material loads that risk overwhelming the normal functions that these ecosystems provide. In this context, the objective of this study is to assess key biogeochemical processes to understand the connections of anthropogenic activities on ecosystem performance in a tropical estuarine lagoon system. This research focuses on a case study area, Dong Ho lagoon in Vietnam, which exemplifies the anthropogenic impacts and management issues facing most of the Mekong coastline and other similar areas in Vietnam. Located at the south-western edge of the Mekong delta, the Dong Ho estuary is subject to material inputs from both local and more remote sources; making it vulnerable to degradation and functional loss. This paper summarises the key findings from an assessment of the Dong Ho estuarine functions and highlights potential risks it is currently facing.

A Multivariate Analysis Framework to Detect Key Environmental Factors Affecting Spatiotemporal Variability of Chlorophyll-a in a Tropical Productive Estuarine-Lagoon System

Here, we demonstrate how a combination of three multivariate statistic techniques can identify key environmental factors affecting the seasonal and spatial variability of chlorophyll-a (Chl-a) in a productive tropical estuarine-lagoon system. Remote estimation of Chl-a was carried out using a NIR-Red model based on MODIS bands, which is highly consistent with the in situ measurement of Chl-a with root mean square error (RMSE) of 15.24 mg m−3 and 13.43 mg m−3 for two independent datasets used for the model’s calibration and validation, respectively. Our findings suggest that the river discharges and hydraulic residence time of the lagoons promote a stronger effect on the spatial variability of Chl-a in the coastal lagoons, while wind, solar radiation and temperature have a secondary importance. The results also indicate a slight seasonal variability of Chl-a in Mundaú lagoon, which are different the from Manguaba lagoon. The multivariate approach was able to fully understand the relative importance of key environmental factors on the spatiotemporal variability of Chl-a of the aquatic ecosystem, providing a powerful tool for reducing dimensionality and analyzing large amounts of satellite-derived Chl-a data.