Coastal Ponds Research Articles

Tracking the seasonal calcification of Cyprideis torosa (Crustacea, Ostracoda) using Mg/Ca-inferred temperatures, and its implications for palaeotemperature reconstruction

Abstract Ostracod shell chemistry data are widely used for palaeoenvironmental reconstruction. Despite this, there has been little systematic research into the implications of the timing of calcification or the duration of each moult stage. Consequently, it is unclear whether palaeoenvironmental reconstructions are recording restricted (inter-seasonal) time periods or reflect the mean annual conditions. The seasonality of shell formation can therefore have implications for palaeoenvironmental reconstructions based on geochemical signatures, especially palaeotemperature, particularly in environments that show large inter-annual variations in water conditions. Cyprideis torosa is a geographically widespread and eurytopic species that has great potential for a range of palaeoenvironmental reconstructions, but inhabits environments with large seasonal and inter-annual variation. Using hourly water and air temperature data, ostracod shell and surface water chemistry from a shallow coastal pond in SE UK, we improve knowledge of the timing of Cyprideis torosa calcification, and thus our understanding of the potential seasonality of signals in palaeotemperature datasets. We suggest seasonal calcification in spring and autumn, with persistence at the adult life stage for up to 12–18 months. Sr/Ca values of C. torosa appear to reflect a Sr/Cawater control on calcification timing and have no temperature dependence. For Mg/Ca, we show a minimum temperature control on calcification of 7 °C, with C. torosa Mg/Ca-inferred temperatures broadly tracking spring and autumn temperatures.

Evaluation of Marsh Terraces for Wetland Restoration: A Remote Sensing Approach

Marsh terracing is a wetland restoration technique that is being implemented in the northern Gulf of Mexico. Marsh terraces are segmented berms of soil built within shallow coastal ponds, designed to increase marsh area and reduce wave energy. Approximately 980 linear km of marsh terraces have been constructed over almost 30 years in Louisiana and Texas to combat subsidence and sea-level rise; however little research has been conducted to determine their effectiveness. The objective of this study was to assess marsh terrace performance. The change in marsh terrace areas was measured over time through remote sensing. This analysis was conducted using one-meter resolution imagery from the National Agriculture Imagery program (NAIP) from 2003 until 2017 from five Louisiana coastal parishes. Twenty terrace fields of study between 10 and 14 years old were randomly selected within each parish. Results show more predominant deposition (55%) than erosion (45%) in marsh terraces. Terrace fields with high channel density and thereby an external sediment supply show more deposition compared to low channel density fields. This is the first study assessing multiple marsh terrace fields performance. Results are promising, especially considering the current rate of sea level rise and subsidence in Louisiana.

Abnormal test growth in Larger Benthic Foraminifera from hypersaline coastal ponds of the United Arab Emirates

The larger benthic foraminifera (LBF) assemblage from shallow hypersaline coastal ponds located in the intertidal area of theUnitedArab EmirateWestern Region was investigated. The studied coastal ponds are located between a lagoonal areawith carbonate sedimentation, and a supratidal, evaporite-dominated, sabkha. Epiphytic larger benthic foraminifera, mostly belonging to the genus Peneroplis, dominate the benthic foraminifera assemblage. At all the sampled locations, the larger benthic foraminifera assemblage is characterised by high percentages of tests with abnormal growth. Dissolution and microboring are also common on the majority of LBF tests. The high percentage of abnormal tests reflects natural environmental stress caused by the instability of physical parameters (particularly high and variable salinity and temperature) in this transitional marine environment. The unique presence of epiphytic species in some of the ponds suggests that epiphytic foraminifera are transported into the ponds attached to floating seagrass and subsequently continue to live in the stressed pond environment.

EKSTRAK BUAH MANGROVE (Sonneratia alba) PADA Artemia salina DALAM MENGHAMBAT INFEKSI Vibrio harveyi TERHADAP SINTASAN BENUR UDANG WINDU (Penaeus monodon) SECARA INVIVO

Vibriosis disease Vibrio harveyi often drops Penaeus monodon production on the traditional coastal ponds of North Kalimantan. The purpose of this study was to find out the active compound extract of Sonneratia alba fruit inhibiting the infection of Vibrio harveyi, which was tested on the larvae of Penaeus monodon in post larvae 12 through the bioerichment of natural feed Artemia salina. This study used an experimental method performed with a Completely Randomized Design (CRD) of 4 treatments and 3 replications. The results showed mangrove fruit extracts containing alkaloids, phenol hydroquinone, flavonoids, saponins, steroids and tannins. Artemia salina bioenrichment succeeded in increasing the survival of Penaeus monodon larvae 78.33% in treatment III (20 ppm). The results of water quality measurements indicate the range at the normal limit for the life of the Penaeus monodon larvae. Keywords : Penaeus monodon, Artemia salina, Vibrio harveyi, Extract Sonneratia alba

Reproductive phenology of submerged macrophytes: A tracker of year‐to‐year environmental variations

AbstractAimsPhenological shifts are useful trackers of climate change effects on species and communities, but few datasets focus on the climate‐driven phenological responses of aquatic ecosystem vegetation. We aimed to analyse the reproductive seasonality of a submerged macrophyte community, the synchrony among coexisting species, and their responses to several environmental factors.LocationA Mediterranean coastal pond in Valencia, Spain.MethodsWe analysed three years of data on a submerged macrophyte community. Plants were collected biweekly or monthly (57 collection dates) to quantify the intensity of flowering/fruiting per species. The reproductive seasonality of the community was tested with circular statistics. The reproductive synchrony of species was calculated with the Augspurger and the Freitas and Bolmgren indexes. The environmental factors driving reproduction in macrophytes were analysed with redundancy analyses.ResultsThe reproductive activity of the community was seasonal (peaking in spring–summer) or non‐seasonal (peaking in spring–summer and autumn) depending on the year‐to‐year variations of precipitations after the summer drought. The synchronization among species in flowering and fruiting (overlap in time and intensity) was low, because the species‐specific reproductive patterns were spread throughout the long Mediterranean growing season. Temperature, water level, and conductivity were the variables that best explained flowering variability in the community, indicating that these factors affected each species differently. Fruiting was temporally correlated to flowering, with different lags depending on the species life cycle.ConclusionsThe species‐specific responses suggest that a warming climate may act as an environmental filter, gradually changing the community structure. The reproductive phenology of submerged macrophytes could act as an early indicator of a changing climate, with charophytes (Characeae) as suitable tracker candidates. Further studies concerning their phenology are needed to assess the resilience of submerged macrophyte communities to drought and assure the long‐term functioning of Mediterranean aquatic ecosystems.

Freshwater diatom assemblages from seabird-inhabited ponds in Hudson Strait, sub-Arctic Canada

Nutrients and contaminants in wastes from seabird colonies can dramatically alter surrounding vegetation, water chemistry, and aquatic communities. Here we examine the effects of nesting Common Eiders (Somateria mollissima) on diatom assemblages from 21 ponds on islands in Hudson Strait, sub-Arctic Canada (63°12′N, 76°52′W). A total of 116 diatom taxa were identified, with assemblages dominated by benthic Diatoma and Nitzschia species typical of freshwater ponds influenced by seabird colonies. Canonical correspondence analysis (CCA), with forward selection and Monte Carlo permutation tests (999 repetitions), identified parameters correlated to seabird inputs, including specific conductivity, Al, and Cd concentrations, as the variables most closely linked to diatom species composition. A diatom-based conductivity inference model was developed using a weighted average with partial least squares (WA-PLS) model (r2boot = 0.723; RMSEP = 0.544) to describe the conductivity optima of the most commonly encountered taxa. Although we found increased numbers of eutrophilous taxa in highly eider-influenced ponds, the diatom assemblages were primarily influenced by conductivity, which was primarily linked to ocean spray, and statistical tests did not identify significant differences between the taxa of high and low eider-influenced sites (ANOSIM; p = 0.429; r = 0.009). This calibration set exhibits the potential use of diatoms as indicators of seabird abundance and density across breeding sites; however, in coastal ponds, ocean spray (and hence conductivity) appears to be a confounding factor affecting diatom assemblages.

The Potential for Homestead Pond Polyculture of Tilapia and Carps in Coastal Bangladesh

A fishers’ women-led Participatory Action Research (PAR) was conducted in 30 homestead ponds to assess the potential for polyculture of Tilapia (Oreochromis niloticus) and major carps Rohu (Labeo rohita) and Catla (Catla catla) in two coastal fishing villages of Bangladesh. Three treatments, namely T1 (Tilapia 200 fish per decimal; 1 decimal=40 m2), T2 (Tilapia 200+ Rohu 32+ Catla 8 fish per decimal) and T3 (Tilapia 200+ Rohu 8+ Catla 32 fish per decimal), each with 5 replicates, were tried in Hossainpur and Anipara villages. Formulated commercial Mega-feed was applied to the ponds twice daily at an initial rate of 10% body weight (bw)/day of Tilapia down to 4% bw/day throughout the culture period. The water quality parameters of ponds including transparency, salinity and dissolved oxygen significantly varied among treatments except temperature and pH and remained within optimum range for carp polyculture except salinity. The survival rate, harvesting weight and yield of Tilapia were significantly highest in T1 (85.63±05%, 258.59±18.76 g & 11073±805 kg/ha, respectively) in Anipara and lowest in T3 (75.63±0.37%, 136.97±10.63 g & 5180±406 kg/ha, respectively) in Hossainpur. The gross fish production was the significantly highest in T1 (11354±806 kg/ha) of Anipara and lowest in T1 (6325±227 kg/ha) of Hossainpur. Statistically, the highest net return (866,627±84874 BDT/ha) was found in T1 of Anipara and lowest in T3 (279,389±46104 BDT/ha) of Hossainpur with a significantly higher benefit-cost ratio (BCR) obtained in T1 (3.26±0.20) for Tilapia and lower in T3 (1.58±0.10) for polyculture Tilapia and carp of Hossainpur. Therefore, it may be concluded that Tilapia production in small homestead coastal ponds has a higher potential than its mix with carps in polyculture for generating food and supplemental income opportunity for coastal fishers’ women in Bangladesh.

The Potential for Homestead Pond Polyculture of Tilapia and Carps in Coastal Bangladesh

A fishers’ women-led Participatory Action Research (PAR) was conducted in 30 homestead ponds to assess the potential for polyculture of Tilapia (Oreochromis niloticus) and major carps Rohu (Labeo rohita) and Catla (Catla catla) in two coastal fishing villages of Bangladesh. Three treatments, namely T1 (Tilapia 200 fish per decimal; 1 decimal=40 m2), T2 (Tilapia 200+ Rohu 32+ Catla 8 fish per decimal) and T3 (Tilapia 200+ Rohu 8+ Catla 32 fish per decimal), each with 5 replicates, were tried in Hossainpur and Anipara villages. Formulated commercial Mega-feed was applied to the ponds twice daily at an initial rate of 10% body weight (bw)/day of Tilapia down to 4% bw/day throughout the culture period. The water quality parameters of ponds including temperature, transparency, pH, salinity and dissolved oxygen significantly varied among treatments except temperature and pH and remained within optimum range for carp polyculture except salinity. The survival rate, harvesting weight and yield of Tilapia were significantly highest in T1 (85.63±05%, 258.59±18.76 g & 11073±805 kg/ha, respectively) in Anipara and lowest in T3 (75.63±0.37%, 136.97±10.63 g & 5180±406 kg/ha, respectively) in Hossainpur. The gross fish production was the significantly highest in T1 (11354±806 kg/ha) of Anipara and lowest in T1 (6325±227 kg/ha) of Hossainpur. Statistically, the highest net return (866,627±84874 BDT/ha) was found in T1 of Anipara and lowest in T3 (279,389±46104 BDT/ha) of Hossainpur with a significantly higher benefit-cost ratio (BCR) obtained in T1 (3.26±0.20) for Tilapia and lower in T3 (1.58±0.10) for polyculture Tilapia and carp of Hossainpur. Therefore, it may be concluded that Tilapia production in small homestead coastal ponds has a higher potential than its mix with carps in polyculture for generating food and supplemental income opportunity for coastal fishers’ women in Bangladesh.

Reconstructing the groundwater recharge history for the Plymouth-Carver Aquifer Massachusetts, USA

Groundwater systems can respond to climate forcing and millennial climate shifts more slowly than other components of the hydrologic cycle, making it difficult to reconstruct the influences and responses of groundwater to changing climate. Here, we test the linkage between climate change and groundwater responses by using water level changes situated in areas with permeable, unconfined aquifers systems. For hydroclimate histories, we compare moisture models from terrestrial water level reconstructions with predictions of available water from a transient earth system climate model. We focus our analysis on several small waterbodies with Holocene-era proxy measurements that are connected to the Plymouth-Carver glacial aquifer in southeastern Massachusetts, USA. Using these pond- and marsh-based records, we reconstruct groundwater recharge histories along individual groundwater flow paths using water level and sea level reconstructions with an analytical solution to the groundwater flow equation. We find that the water level reconstructions could contain both hydroclimate and sea level signals, with the early Holocene water levels primarily due to hydroclimate with predominantly a sea level signal after ∼7.5 ka cal BP. Our results indicate that sea level influenced coastal pond water levels, and sea level may play a more significant role than effective moisture over certain periods in the Holocene for terrestrial water bodies hydraulically connected to the evolving position of the coast. Future climate reconstructions developed from water level histories from low-elevation inland water bodies may benefit from examining the potential influence of sea level in addition to hydroclimate, but additional model validation and consideration of other cryosphere and glacial processes are needed to fully resolve sea level as a driver of terrestrial water level change.

A Tool for Rapid Assessment of Hydrological Connectivity Patterns in Texas Coastal Wetlands: Linkages between Tidal Creeks and Coastal Ponds

Coastal salt marshes are heterogeneous, spatially complex ecosystems. The degree of hydrological connectivity in these systems can be a significant driver in the flux of energy, organisms, and nutrients across the marsh landscape. In tidally driven systems, the frequency and magnitude of hydrological connection events results in the creation of a matrix of intermittently connected coastal wetland habitats, some of which may be hydrologically isolated or partially drained at any given time. Previous approaches to understanding landscape-level hydrologic connectivity patterns have required either intensive long-term monitoring or spatially explicit modeling. In this paper, we first describe a 13-month field study in the Guadalupe Estuary of the Texas Gulf Coast that linked hydrological connectivity patterns between a saltwater pond to water levels in an adjacent tidal creek and nearby San Antonio Bay. We next describe the integration of these field data with high-resolution digital elevation models and environmental parameters to develop a spatially explicit model that is a Simulation of Landscape-level Oscillations in Salt Marsh Hydroperiod (SLOSH). We evaluated the ability of SLOSH to simulate trends in landscape-level patterns of hydrological connectivity between a tidal creek and an inland marsh pond. Magnitude and periodicity of simulated and observed water-level fluctuations in the pond were similar. Highest creek water levels, resulting in high frequency and duration of hydrological connectivity with the pond, corresponded with the highest bay water levels, which occurred during September and October. Lowest creek water levels, resulting in low frequency and duration of hydrological connectivity, corresponded with the lowest bay water levels, which occurred during December through February. By simulating the pulsing structure of salt marsh hydrology, SLOSH creates the foundation on which to assess how additional drivers (precipitation, wind, freshwater inflows, etc.) can influence coastal marsh hydrology and overall ecology. Citation: Swannack TM, Wozniak JR, Grant WE, Davis SE III. 2019. A tool for rapid assessment of hydrological connectivity patterns in Texas coastal wetlands: linkages between tidal creeks and coastal ponds. Texas Water Journal. 10(1):46-59. Available from: https://doi.org/10.21423/twj.v10i1.7073.

Distribution of the highly toxic clinging jellyfish Gonionemus sp. around the island of Martha\u2019s Vineyard, Massachusetts, USA

In recent years, the cryptogenic and often highly toxic hydrozoan Gonionemus sp. has appeared in new locations around the globe and has become increasingly abundant in the Northwest Atlantic where it is now associated with severe stings. Several such stings have been documented from the island of Martha’s Vineyard, located approximately 8 km south of the Cape Cod, Massachusetts coast. It appears that Gonionemus sp. may be expanding its range in this region. Here we surveyed for medusae in the major coastal ponds along the perimeter of Martha’s Vineyard, refined our knowledge of Gonionemus sp. habitat by recording salinity, water depth, and bottom type from surveyed areas, and obtained a basic population life history assessment by measuring the sizes and sex ratios of medusae collected in the surveys. We found Gonionemus sp. present in five ponds: Farm Pond, Sengekontacket Pond, Lake Tashmoo, Stonewall Pond, and Edgartown Great Pond. Medusae were associated with eelgrass meadows in all cases. Salinities for medusa populations ranged from 18 ppt in Edgartown Great Pond to 29 ppt in the other ponds. The Farm Pond and Stonewall Pond medusae were significantly smaller than those from other ponds and were comprised of primarily immature individuals despite sampling relatively later in the season, suggesting factors other than temperature may be affecting medusa growth. For mature medusae, sex ratios were highly biased, suggesting a strong clonal component to population growth. Edgartown Great Pond contained only males and thus may represent an entirely clonal population. These medusae are the first record of Gonionemus sp. in Edgartown Great Pond, despite a long history of study. Medusae were most abundant in the portion of the pond near the town landing, which suggests that the medusae could have originated by clonal polyps, frustules, or cysts associated with a boat hull. Given the presence of male and female medusae in other parts of Martha’s Vineyard, it seems likely that additional genetic individuals will arrive in the near future, potentially establishing a sexually reproductive population.

Toxicity and haemolytic activity of a newly described dinoflagellate, Heterocapsa bohainensis to the rotifer Brachionus plicatilis

The algae Heterocapsa bohaiensis is a newly described species of dinoflagellate associated with Penaeus japonicus and larvae of Eriocheir sinensis in a coastal pond of Liaodong Bay China. The rotifer Brachionus plicatilis is used as live feed for aquaculture organisms including prawns and crabs larvae. To evaluate the potential toxicity of H. bohaiensis, the effects on Brachionus plicatilis and haemolytic activity were investigated in this study. The results showed that H. bohaiensis had significant toxic effect on B. plicatilis, and this effect was dependent on the cell concentration. Significant rotifer growth suppression was observed in the ruptured cells of H. bohaiensis with ultrasonic. Relatively similar rotifer mortalities were induced both in the light and in the dark. Interestingly, haemolysis to erythrocytes was also caused in a cell density-dependent and time-dependent manner, which meant the results of haemolytic activity were consistent with the toxicity. Therefore, haemolytic toxins were considered to be involved in the toxic mechanism of H. bohaiensis against rotifers. Then, the concentrations of calcium were measured in the mastax, stomach and ovary of B. plicatilis. Obviously increased fluorescence intensity was found in the stomach, which indicated the alteration of calcium homeostasis and membrane permeability after ingesting H. bohaiensis. These results implicated haemolytic activity as a causative factor linked to the toxicity of H. bohaiensis against B. plicatilis. The results contributed to research the production and control of H. bohaiensis toxins.

Drivers of the beta diversity of aquatic plant communities along a latitudinal gradient in southern Brazilian coastal ponds

AbstractQuestionsIs macrophyte beta diversity in temporary ponds generated mainly by turnover along a latitudinal gradient? Is macrophyte beta diversity more strongly correlated with differences in local environmental conditions and climate than geographical distances? Are hydrophytes and helophytes correlated with distinct environmental drivers?LocationSouthern Brazilian Coastal Plain.MethodsMacrophyte communities were studied in 24 ponds distributed along a latitudinal gradient. Beta diversity was calculated with the Sorensen dissimilarity index (and further partitioned into turnover and nestedness components). We assessed the individual correspondence of macrophyte beta diversity with local (water quality and habitat structure; after pre‐selection procedures on each explanatory matrix) and climatic environmental drivers, as well as with the geographical distances, through Mantel correlation tests. Partial Mantel tests were carried out to assess the correspondence of beta diversity with the climatic drivers and geographical distances while controlling for the effect of each explanatory matrix. Separate assessments were carried out for subsets of hydrophytes and helophytes.ResultsMacrophyte beta diversity was mainly generated by turnover. Mantel tests detected significant correlations of macrophyte beta diversity with climatic rather than with local environmental drivers. Partial Mantel tests detected significant relationships only between macrophyte beta diversity and climate (rather than geographical distances). Helophytes were more strongly correlated with climate than hydrophytes, and geographical distances were significantly correlated to hydrophyte beta diversity only.ConclusionsOur results indicate that macrophyte communities in southern Brazilian coastal temporary ponds are mainly assembled by species sorting processes, although the contribution of each assembly mechanism differed between functional groups (spatial processes were more important for hydrophytes than helophytes). The distinct relationships of hydrophytes and helophytes with climate suggest different sensitivity of each functional group to environmental changes in temporary ponds.

ALTERNATIVE PRACTICE FROM COASTAL POND TO RECIRCULATION AQUACULTURE SYSTEM

Coastal pond aquaculture used solar energy to produce oxygen via phytoplankton with their cultivation can be extensive such as the culture of low value cultured animals. Pond encompasses a larger culture area for juvenile or grow-out culture which is depending on their carrying capacity of the pond. There is no feeding and the amount of food available depends on pond management which can be increased by manuring. As well as in hatcheries that require a very well environmental control, Recirculation aquaculture systems (RAS) tend to occupy a small area to culture high value species at high densities. The key parameter affecting RAS is the biological filtration system that removes metabolic and other waste products. This contains bacteria which break down the ammonia and nitrite in the water. Moreover, the food from RAS is supplied externally from cultured or formulated feed. Recirculation systems offer the advantage over pond aquaculture of being able to control the environment and water quality parameters to optimise fish health. For production of commodity food fish that are low in price, pond aquaculture is better than recirculation system due to their lower overheads and production cost as the environment acts as a natural water reconditioning system compared to money spent on water recirculation technology. In developing countries, pond will still remain dominant due to the ease of culture and the low initial investments. While, in developed countries, the growing concern about environmentally friendly discharges, the high labour costs and the need for controlling niche markets will result in the adoption of recirculation technology and the production of high value species at high densities. In comparison to pond culture, RAS offered more control and independent from the environment influence.

Climate and human influence on late Holocene fire regimes in the British Virgin Islands

AbstractGlobal climate change poses significant threats to the Caribbean islands. Yet, little is known about the long-term disturbance regimes in island ecosystems. This research investigates 2000 yr of natural and anthropogenic fire disturbance through the analysis of a latitudinal transect of sediment records from coastal salt ponds in the British Virgin Islands (BVI). The two research objectives in this study are (1) to determine the fire regime history for the BVI over the last 2000 yr and (2) to explore ecological impacts from anthropogenic landscape modification pre- and post-European settlement. The magnitude of anthropogenic landscape modification, including the introduction of agriculture, was investigated through a multiproxy approach using sedimentary records of fossil pollen and charcoal. Our results suggest fire regimes from Belmont Pond, Thatch Island, and Skeleton Pond have been influenced by human activity, particularly during the postsettlement era, from 500 cal yr BP to modern. Our results suggest that fire regimes during the Medieval Climate Anomaly were responding to changes in climate via dominant atmospheric drivers. The presettlement fire regimes from these islands suggest that fires occurred every 90 to 120 yr. This research represents a significant data contribution to a region with little disturbance and vegetation data available.

Laguna Verde Bay s sediments origin and its heavy metals content (Al, Fe, Cu, Mn, Pb, and Hg), Valparaiso, Chile

Laguna Verde Bay, a World Biosphere Reserve, seems to be barely uncontaminated due to its isolated geographical position (18 km south of Valparaiso, Chile) and low amount of anthropogenic activities. At its coastal border, there is a thermoelectric generator (using coal since 1939 and diesel since 2007 as fuel), a small village (≈10.000 inhabitants) and a local fishermen’s wharf. A freshwater creek flows into the beach, creating a small coastal pond that sporadically overflows into the bay. With the objective of estimating the origin of the Laguna Verde Bay surface sediments and its heavy metal pollution level, the content of Total Organic Matter (TOM), organic carbon to total nitrogen ratio (C:N ratio), stable carbon isotope ratio (δ 13C ), Al, Fe, Cu, Mn, Pb and Hg in samples collected in August 2015, were measured. According to the δ 13C values, the sediment origin was mostly terrestrial, with an allochthonous content greater than 50%. Since there is no legislation in Chile to establish the heavy metal concentrations for unpolluted marine sediments, a normalized metal enrichment factor (NEF) was computed to infer the contamination level. Despite the high Fe and Pb contents in the bay’s sediment at two stations (13.3 mg g -1 and 18.0 µg g -1 , respectively), the NEF values in the bay generally correspond to a low level of pollution.

Predicting impacts of sea level rise on wintering redhead ducks along the lower Texas Coast

The potential impacts of sea level rise to wildlife populations and their habitats are of concern. Localized relative sea levels have been rising at elevated rates compared to global sea levels, and this trend will impact coastal plant communities, particularly wetlands. The Laguna Madre, a hypersaline lagoon, is home to nearly 80% of North America's redheads (Aythya americana) during winter. The large, shallow lagoon provides optimal growing conditions for seagrasses, including shoalgrass (Halodule wrightii), the redhead's primary winter food. Adjacent to the Laguna Madre are coastal ponds, on which redheads rely for fresh water. The close proximity of these freshwater sources to the coast makes them vulnerable to saltwater intrusion due to sea level rise. Using Sea Level Affecting Marshes Model (SLAMM), we modeled the impacts of sea level rise on coastal ponds and foraging areas along the lower Texas coast through the year 2100. We also determined which coastal habitat types would be most affected by rising sea levels. The SLAMM model indicated that 9 land cover types had a ≥50% change in occurrence from the initial 1999 time period to 2100. The model also predicted that 93 of the known 156 coastal ponds would become inundated with salt water. The predicted loss of foraging habitat and its typical proximity to coastal ponds creates a need to identify where conservation and enhancement of wintering redhead habitat should be placed to mitigate the effects of sea level rise.

Breeding eider ducks strongly influence subarctic coastal pond chemistry

Arctic freshwater ponds are typically pristine and oligotrophic, however seabird biovectors can markedly alter water quality via enrichment with marine-derived nutrients and bioaccumulated metals. These ornithogenic inputs can be the dominant factor structuring aquatic biota and the surrounding island flora. Here, we measured a suite of limnological water chemistry variables and sediment geochemistry from 21 freshwater ponds influenced by Common Eiders (Somateria mollissima) in Hudson Strait, near the northern communities of Cape Dorset (Nunavut) and Ivujivik (Quebec). Nest counts and sedimentary δ15N values were used as proxies of bird abundance. Nutrient-rich guano from the nesting eiders visibly promoted the growth of catchment vegetation. Elevated metal (Al, Cd, Zn), metalloid (Se), and nutrient concentrations (N, P) in the water of eider-affected sites were recorded (Sign test; p = 0.004), but the proximity of many sites to the coast meant that variables related to ocean spray (conductivity, Na+, Mg2+, Cl−, Sr) confounded the effects of birds on pond water chemistry. In contrast, sediment geochemistry appeared to more clearly characterize sites according to the level of eider activity in their catchments by tracking Pb, Cd, N, and P sedimentary concentrations (Sign test; p = 0.02). These results have direct implications for reconstructing historical eider population trends using sediment archives, which is necessary to inform effective conservation management strategies.

Biogeochemistry and sedimentology of Lago di Lesina (Italy)

The Lago di Lesina (Lesina Lake, southeastern Italy) is a coastal pond located on an alluvial plain to the north of Gargano Promontory. The aim of this work was to study the depositional and hydrological processes, the benthic environment and the heavy metal sediments pollution of Lesina Lake. The study was carried out by Redox potential, water content, grain-size, mineralogical and biogeochemical analyses in surface sediments collected from 100 sampling stations in the coastal pond bottom. The results showed a predominance of three types of bottom pelitic sediments of different origins and compositions: siliciclastic, carbonatic, and organic. Siliciclastic sediments, which were found especially in the western basin and in the northwestern sector of the central basin, are due to inputs from Acquarotta Canal, some intermittent western streams, and deflation by northerly winds of the sandy barrier that separates the lake from the sea. Carbonate sediments are carried by streams and canals draining the carbonate rocks of the Gargano Mountains and entering the lake from its eastern and southeastern border, these sediments are predominant in the eastern basin and in the southeastern sector of the central basin. Organic matter is abundant throughout the whole lake; it is due to the high productivity of the Lago di Lesina waters that are rich of nutrients for inputs of waters draining the surrounding intensively cultivated agricultural areas. The finer bottom sediments of the lake tend to be removed from the shallower bottoms between the central and eastern sub-basins and near the borders to be deposited in the central portion of the central and western sub-basins. Heavy metal sediment pollution due to anthropic inputs is limited and consists of As, Pb, Cu, and Ni in the western basin, Cu, Zn, and Ni in the eastern basin, and Pb along the northern border.

Drivers of beta diversity of Odonata along a forest–grassland transition in southern Brazilian coastal ponds

AbstractAssessment of β diversity patterns in relation to environmental and spatial drivers can provide useful insights into the underlying mechanisms structuring communities (deterministic and dis...