Low Tide Periods Research Articles

Metabolic rates of different demographics in the sand fiddler crab Leptuca pugilator.

Studies on animal energetics often focus on standardized metabolic rates to facilitate comparison across systems. Yet these standardized measurements often do not capture the realistic demographic and environmental variation that is common in natural settings. Rather, individuals included in these studies are often non-reproducing, uninjured, resting adults that have not recently eaten-far from a representative sample. We measured the respiratory rates of the sand fiddler crab Leptuca pugilator in air immediately after capture in the field, and compared rates between males, females of different reproductive states, and juveniles. As expected, we show that metabolic rates were influenced by body mass and activity level. We also show that being vitellogenic or gravid had only minor impacts on metabolic costs of females. Importantly, we demonstrate how considering demographics allows for the detection of phenomena that would otherwise go unnoticed. We found that field metabolic rates of L. pugilator in air are as much as an order of magnitude higher than previous standard metabolic rates measured on post-prandial, quiescent individuals. These higher rates may reflect a combination of high activity and active digestion, as fiddler crabs actively feed during low tide periods. Our results highlight the importance of considering differences in sex, life history stage, and reproductive state of organisms in fluctuating environments, such as intertidal habitats, when assessing energy expenditure.

The Implications of Seeping Hydrocarbon Gases in the Gunsan Basin, Central Yellow Sea, off the Southwest of Korea

A detailed analysis of high-resolution (3.5 kHz) chirp seismic profiles acquired in the Gunsan Basin of the central Yellow Sea revealed that hydrocarbon gases are actively seeping via the formation of many plumes. The uppermost sedimentary layer was acoustically confirmed to be fully or partially charged with gases. Somewhat favored by the low-tide period, episodic gas seepage is mainly associated with the underlying fault systems of Cretaceous-Cenozoic sedimentary strata in the southwestern part of the basin. Catastrophic gas expulsion seems to have formed a crater at the sidewall of a sedimentary ridge and two diapirs. Here, methane is poorly concentrated but rich in the heavy carbon isotope (δ13C, −52.6‰ to −44.7‰ The Vienna Peedee Belemnite [VPDB]), indicating that methane formed mainly through biodegradation of heavy oils at depth remains in the shallow sediments following its expulsion. Episodic rapid upward advection of porewater is also manifest by unmixed heavy methane trapped in the upper part of the primary biogenic methane (δ13C, about −90‰ VPDB)-filled sediment core. These findings imply that the Gunsan Basin fulfills the requirements for possible generation and preservation of oil and gas, like the petroliferous basins of eastern China and the Yellow Sea.

Occurrence of microplastics and ecological risk assessment during tidal changes in the Chao Phraya River estuary, Thailand

River estuaries are specific transition zones that connect coastal and terrestrial environments and are recognized as primary conveyors for land-derived plastics to open oceans. The present study is the first to investigate tidal effects on microplastics (MPs) in the Chao Phraya River estuary. MPs (16–5000 μm) were collected from the water column during the changes in tidal current in order to analyze abundance, characteristics, and ecological risk. The abundance of MPs varied from 1.37 to 4.51 pieces/L and an average of 4.0 ± 3.8 pieces/L were found during the tidal cycle, which implied moderate to relatively high contamination when compared to other estuaries. Moreover, the average abundance of MPs during the low tide period was comparatively higher than that in other tidal phenomena. Morphological characteristics revealed that shape of fragments, shade of blue, size of 16–100 μm and PTFE is dominant in the MPs. The pollution load index (PLICPRE) was 5.98, which denoted that the Chao Phraya River estuary is polluted with MPs at a low contamination level. In contrast, the risk index (RICPRE) of MPs in the water column during the tidal cycle was 318.8, which indicated that the estuarine ecosystem of the Chao Phraya River is under considerable risk. In the present study, an ecological risk assessment was conducted for the Chao Phraya River estuary, which provides basic reference data for the management of pollution control related to MPs in the Chao Phraya River basin.

Location also matters: The oxidative response of the intertidal purple mussel Perumytilus purpuratus during tidal cycle

For sessile intertidal organisms, periods of low tide impose both cellular and physiological challenges that can determine bathymetric distribution. To understand how intertidal location influences the cellular response of the bivalve Perumytilus purpuratus during the tidal cycle (immersion-emersion-immersion), specimens from the upper intertidal (UI) and lower intertidal (LI) of bathymetric distribution were sampled every 2 h over a 10-h period during a summer tidal cycle. Parallelly, organisms from the UI and LI were reciprocally transplanted and sampled throughout the same tidal cycle. Levels of oxidative damage (lipid peroxidation and protein carbonyls) as well as total antioxidant capacity and total carotenoids were evaluated as cellular responses to variations in environmental conditions throughout the tidal cycle. The results indicate that both the location in the intertidal zone (UI/LI), the level of aerial exposure, and the interaction of both factors are determinants of oxidative levels and total antioxidant capacity of P. purpuratus. Although oxidative damage levels are triggered during the low tide period (aerial exposure), it is the UI specimens that induce higher levels of lipid peroxidation compared to those from the LI, which is consistent with the elevated levels of total antioxidant capacity. On the other hand, organisms from the LI transplanted to the UI increase the levels of lipid peroxidation but not the levels of protein carbonyls, a situation that is also reflected in higher levels of antioxidant response and total carotenoids than those from the UI transplanted to the LI. The bathymetric distribution of P. purpuratus in the intertidal zone implies differentiated responses between organisms of the lower and upper limits, influenced by their life history. A high phenotypic plasticity allows this mussel to adjust its metabolism to respond to abrupt changes in the surrounding environmental conditions.

Variation in metabolic rate during low tide aerial exposure in the Asian shore crab Hemigrapsus sanguineus

Intertidal animals deal with physical gradients daily that create stressful conditions across the shore. These physical gradients influence the physiological performance of organisms, requiring responses that may differ with height on the shore. We examined the respiratory response to aerial exposure in the invasive Asian shore crab Hemigrapsus sanguineus during periods of low tide emersion using two field experiments. The first experiment simultaneously measured respiration of individuals collected from different heights on the shore, which had therefore been emersed for different lengths of time. The second experiment measured respiration of individuals collected at different times from the same tidal height. Respiration rates of crabs in both experiments increased immediately after emersion, nearly doubling by and peaking at ~ 1.5 h of aerial exposure, before decreasing again over the next 1.5 h. These results suggest that the energetic cost of low tide exposure is greatest shortly after emersion during the first half of the typical low tide period, but then decreases thereafter. These respiration patterns facilitate the broad intertidal distribution of this species on rocky shores throughout its range.

Habitat variety and behaviour of the Sanderling (Calidris alba) in an urban neotropical coastal wetland

Sanderling Calidris alba is a migratory coastal bird species whose populations are affected by climatic and anthropogenic issues. Additionally, its behavioural patterns depend on habitat variety. The aim of this study was to evaluate the variation in the frequency and duration of C. alba behaviour in relation to habitat variety in a Peruvian coastal wetland. Based on types of behaviour recorded in a previous study of C. alba during August and September 2019 at low, mid and high tide periods in three habitats of the Coastal Wetland Poza La Arenilla (HCPA) (La Punta, Callao, Peru), differences and diversity in the frequencies and durations of such behaviour between habitats were assessed according to tide condition. Additionally, a correlation analysis between the duration and frequency of behaviour for each habitat according to tide condition was conducted. General differences in behaviour (frequency and duration) between habitats were found, although there was a high similarity of behaviour between areas particularly when mid- and high tide levels were present. The greatest diversity of behaviour, both in frequency and duration, was observed generally during mid-tide conditions in rocky habitats. In most cases, there was a high correlation between the frequency and duration of behaviour for habitats according to tide condition. It is concluded that mid-tide conditions are associated with greater availability of soft substrates, favouring a wide variety of types of behaviour for C. alba, including behaviour related to foraging and locomotion.

2013–2022年福建漳江口互花米草分布无人机遥感数据集

The invasion of exotic Spartina alterniflora into Chinese coastal wetlands poses a threat to biodiversity and ecosystem functions. Thus monitoring the spatio-temporal distribution of the invasion is important for the conservation/restoration and scientific management of coastal wetlands. This dataset includes S. alterniflora spatial data, derived from UAV-based RGB photos over Zhangjiang Estuary, Fujian Province from 2013 to 2022. Using a drone equipped with a visible light camera, we selected low-tide periods during the day, we captured the aerial images in the Zhangjiang Estuary wetland in Fujian Province from 2013 to 2022. Subsequently, we employed the dynamic structure-from-motion (SFM) techniques to reconstruct a three-dimensional model by mosaicking the collected aerial images to obtain a digital orthophoto image covering the study area. This process was repeated annually, resulting in a total of ten orthophoto images. Based on the classified data derived from these orthophoto images, the spatial distribution data of S. alterniflora over ten consecutive years were extracted. The high-quality UAV photos in this dataset are comprehensive and uniformly color-balanced. Located within the Zhangjiang Estuary Mangrove National Nature Reserve with coastal wetland vegetations such as mangroves and S. alterniflora, the study area is one of the most typical mangrove-S. alterniflora ecotones in China. This long-term (over ten consecutive years) and high-resolution (20 cm) image dataset for mangrove-S. alterniflora ecotone can be used in many studies including monitoring coastal wetland vegetation succession, mangrove conservation and restoration, and S. alterniflora invasion.

Using Multisource High-Resolution Remote Sensing Data (2 m) with a Habitat–Tide–Semantic Segmentation Approach for Mangrove Mapping

Mangrove wetlands are hotspots of global biodiversity and blue carbon reserves in coastal wetlands, with unique ecological functions and significant socioeconomic value. Annual fine-scale monitoring of mangroves is crucial for evaluating national conservation programs and implementing sustainable mangrove management strategies. However, annual fine-scale mapping of mangroves over large areas using remote sensing remains a challenge due to spectral similarities with coastal vegetation, tidal periodic fluctuations, and the need for consistent and dependable samples across different years. In previous research, there has been a lack of strategies that simultaneously consider spatial, temporal, and methodological aspects of mangrove extraction. Therefore, based on an approach that considers mangrove habitat, tides, and a semantic segmentation approach, we propose a method for fine-scale mangrove mapping suitable for long time-series data. This is an optimized hybrid model that integrates spatial, temporal, and methodological considerations. The model uses five sensors (GF-1, GF-2, GF-6, ZY-301, ZY-302) to combine deep learning U-Net models with mangrove habitat information and algorithms during low-tide periods. This method produces a mangrove map with a spatial resolution of 2 m. We applied this algorithm to three typical mangrove regions in the Beibu Gulf of Guangxi Province. The results showed the following: (1) The model scored above 0.9 in terms of its F1-score in all three study areas at the time of training, with an average accuracy of 92.54% for mangrove extraction. (2) The average overall accuracy (OA) for the extraction of mangrove distribution in three typical areas in the Beibu Gulf was 93.29%. When comparing the validation of different regions and years, the overall OA accuracy exceeded 89.84% and the Kappa coefficient exceeded 0.74. (3) The model results are reliable for extracting sparse and slow-growing young mangroves and narrow mangrove belts along roadsides. In some areas where tidal flooding occurs, the existing dataset underestimates mangrove extraction to a certain extent. The fine-scale mangrove extraction method provides a foundation for the implementation of fine-scale management of mangrove ecosystems, support for species diversity conservation, blue carbon recovery, and sustainable development goals related to coastal development.

Community Structure of Marine Macrofauna at Diu coast, Gujarat, India

The marine ecosystem support variety of habitat that consequently supports high species diversity. The present study investigated the diversity of marine macrofauna in the rocky intertidal zone of Diu, Gujarat. Survey was carried out from 4 different sites during April 2022 to March 2023. During the study, all the study sites were surveyed regularly on monthly basis during the lowest low tide period. During the examination, the encountered fauna was carefully observed along the coast using a Quadrat method and visual encounter method and extensive photography was carried out. This study demonstrates 70 species of macrofauna at coastal area of Diu. The highest diversity was observed in the phylum Mollusca (37 species), followed by phylum Arthropoda (16 species), Cnidaria (8 species), Porifera (4 species), Annelida (species 2), Echinodermata (2 species), Platyhelminthes (1 species). This study highlights the importance of protecting the diverse marine habitats in Diu and emphasizes the need for further research on the ecology and conservation of the region’s unique marine biodiversity.

Application of MIKE model for simulation of wastewater dispersion in the project of eco-tourism and residential areas of Rach Tram - Phu Quoc, Kien Giang, Vietnam

This study aims to explore the transmission of pollutants from the domestic wastewater of the Rach Tram - Phu Quoc eco-urban project. To achieve this, the Ecolab module of the Mike model is employed. The dispersion of pollutants is influenced by both hydraulic and wind conditions. Notably, under southwest wind condition, the dispersion of pollutants is considerably more pronounced compared to that observed during the Northeast monsoon. Pollutant concentrations exhibited a tendency to move upstream along the Rach Tram river during high tide, while during low tide periods, they tended to move towards the sea. The results of the study indicated that concentrations of Total Suspended Solids (TSS), Biochemical Oxygen Demand (BOD5), Ammonium (NH4+), and Total Phosphorus (TP) in the Rach Tram river and its estuary were found to be 3–8 times higher than the defined standard of Vietnam. However, when appropriate wastewater treatment measures were implemented (scenario 2), the levels of pollutants were observed to be lower the permissible environmental protection standards.

The exploitation of biofilm by migrant western sandpipers (Calidrismauri)

Assessing the quality of migratory shorebird stopover sites requires good measures of food availability. We developed simple methods to measure biofilm grazing by migrant western sandpipers (Calidris mauri), a species for which biofilm is an important dietary component. We used a field-portable chlorofluorometer to measure the density of chlorophyll-a (Chl-a) in surficial biofilms on Roberts Bank, a large intertidal mudflat in British Columbia, Canada, during northward migration.Chl-a density begins at a low level during each diurnal emersion period, and increases steadily during emersion at 4.1 mg m−2 h−1 for a total of ∼24.6 mg m−2 over a typical 6 h emersion period and ∼41 mg m−2 over a 10 h emersion period. Western sandpipers grazed at 1.35–1.45 mg Chl-a m−2 min−1, thus biofilm production supports 17.6 min m−2 of grazing time during a 6 h low tide period and 29.3 min m−2 during a 10 h period. During peak northward migration, the average grazing intensity of western sandpipers over an intertidal emersion period was 3.3–6.4 min m−2, suggesting that biofilm accumulation was 2.7–8.8 fold greater than the amount consumed. We found Chl-a density was highest (∼65 mg per m2) within 40 m of the shoreline. Grazing intensity was lowest close to shore, where predation risk from falcon attacks is highest. Grazing intensity peaked at 240 m and then declined, lowering Chl-a density at greater distances to a uniform level of ∼54 mg m−2. These results indicate that interactions between biofilm production and sandpiper grazing underlie spatio-temporal patterns in biofilm abundance on Roberts Bank.

Surface flow modulation by river discharges in a tropical micro-tidal estuary

The typical bidirectional pattern of subtidal flow observed at the mouths of estuaries is produced by inflows during high-tide (flood) and outflows during low-tide (ebb) periods. This flow pattern can be modulated in the presence of a strong river discharge, as observed for the Alvarado Estuary (western Gulf of Mexico) during the rainy season. Herein, six transect repetitions were obtained using a towed Acoustic Doppler Current Profiler (ADCP) at an average speed of approximately 2 m/s during a diurnal tidal cycle from September 20 to 21, 2009. The water column during this period was strongly stratified at the mouth of the estuary due to the amount of discharge from the Papaloapan River. Furthermore, the temperatures within the estuary were directly related to the distance from the Papaloapan River. Based on salinity data obtained at four locations along the estuary, the Alvarado Estuary could be considered for the first time as a transitional system from oligohaline to mesohaline (salinities between 5 and 18). The currents and backscatter intensities of the ADCP revealed concentrated areas of suspended particles in the deepest area of the estuary during flood tide periods. During ebb tide periods, estuarine water primarily exited through its mouth (∼90%), followed by the artificial channel (∼10%) located in the northernmost area of the estuary. The residence time during this season was 3.99 days. Finally, the typical estuarine flow pattern observed during flood and ebb tide periods was only depicted near the bottom of the mouth of the estuary. However, the near-surface flow was always toward the ocean (outflow), regardless of the tidal stage.

Heat stress increases risk taking in foraging shorebirds

Abstract Animals often face a trade‐off between food acquisition and predation/disturbance avoidance. Yet, the extent to which this trade‐off is affected by modulating factors such as thermal risk and foraging opportunities has been largely overlooked. Here, we examined the influence of temporal and environmental gradients on the flight initiation distance (FID, the distance at which animals flee from an approaching human‐simulated predator) and escape mode (flying/low risk versus running/low cost) in 16 species of shorebirds foraging on tidal flats of the Bijagós Archipelago, Guinea‐Bissau. We measured escape responses throughout the low tide period during wet and dry seasons and simultaneously recorded microclimate variables and occurrence of heat‐reduction behaviour (ptiloerection). Furthermore, we measured corticosterone metabolites (CORTm) from droppings in red knots Calidris canutus to assess whether ptiloerection is associated to a physiological stress response to hot conditions. Overall, birds tolerated a closer approach at higher environmental temperatures and when showing ptiloerection. They also had shorter FIDs during the dry season and towards the start/end of the low tide period. FIDs also increased with body mass and decreased in areas with more human presence. In red knots, individuals showing ptiloerection had higher levels of CORTm, demonstrating a link between physiological and behavioural stress coping responses to heat events. Our results suggest that heat‐stressed shorebirds take greater risks, supporting the idea of a thermoregulation–predation risk trade‐off. They also indicate that shorebirds adjust risk taking to tidal and seasonal cycles, generally reducing FIDs when the energetic costs of escape are expected to be large. Finally, they suggest that shorebirds habituate to non‐lethal human presence and respond to perceived predation risk in accordance with the predictions of optimal escape theory. These results are relevant to many animals that face a tight window for foraging activity while being exposed to predation/disturbance and heat during the day. We discuss management implications of our results in the context of global change. Read the free Plain Language Summary for this article on the Journal blog.

Behavioural adaptation to heat stress: shell lifting of the hermit crab Diogenes deflectomanus

Behavioural responses to heat and desiccation stress in ectotherms are crucial for their survival in habitats where environmental temperatures are close to or even exceed their upper thermal limits. During low tide periods when pools in intertidal sediments heat up, a novel shell lifting behaviour (when hermit crabs crawl out of pools and lift up their shells) was observed in the hermit crab, Diogenes deflectomanus, on tropical sandy shores. On-shore measurements revealed that the hermit crabs left pools and lifted their shells predominantly when pool water exceeded 35.4 °C. Standing on emersed substrates above the pool water, the hermit crabs maintained their body temperatures at 26 – 29 °C, ∼ 10 °C lower than temperatures at which their physiological performances (as measured using heart rate) reached the maximum. This mismatch between preferred body temperatures and temperatures at maximal physiological performance was also observed under a laboratory controlled thermal gradient, where hermit crabs spent more time at 22 – 26 °C as compared to > 30 °C. These behaviours suggest a thermoregulatory function of the shell lifting behaviour, where the hermit crabs can avoid further increase in body temperatures when pools heat up during low tide periods. Such a behavioural decision allows the hermit crabs to be less prone to the strong temporal fluctuation in temperatures experienced during emersion periods on thermally dynamic tropical sandy shores.

The Effect of a Climate Event on Voice-Related Processes in Seniors

Purpose: This project considered the relationship of harmful algal blooms, specifically red tide, to patient reports of respiratory diseases, use of respiratory medications, reflux symptoms, excessive coughing/throat clearing, water consumption, voice handicap scores, clinician judgments of voice quality, and voice therapy outcomes in senior voice patients in coastal Southwest Florida. Method: A retrospective chart review of 131 seniors receiving voice therapy during 2013–2019 was conducted. Patients formed two groups—those evaluated during periods of high versus low red tide. Patient reports, clinician ratings, and therapy outcomes were analyzed with nonparametric statistics to determine differences between patient groups. Results: No relationship was found between the presence of high red tide and reports of airway disorders, use of airway medications, coughing/throat clearing, Reflux Symptom Index scores, or voice therapy success. A significant relationship was found between high red tide months and ratings of voice severity and Voice Handicap Index scores. Conclusions: Harmful algal blooms may have negatively impacted the voices of seniors in this study, as shown by higher clinician voice severity ratings and higher patient perceptions of voice handicap during periods of high red tide. While voice success was still achieved by many of these seniors, speech-language pathologists should be aware of environmental issues and their possible negative impacts on voice.

Assessment and Optimization of Water Resources Regulation for River Networks in the Tidal Plain—A Case Study of the Qingsong Area in Shanghai

The plain river network area has a developed economy, a large population, a complex water system, and weak hydrodynamics. In order to improve the hydrodynamic conditions of the plain river network area, clean water sources are introduced through water resources regulation to supplement the ecological water quantity of the river and effectively improve the water environment of the river. In this paper, the Qingsong area in Shanghai is used as the research object. Prototype observation, numerical simulation, and other methods are used to build a hydrodynamic mathematical model of the river network in the Qingsong area, evaluate the water resources regulation effect of the Qingsong area, and put forward two optimization schemes. The results indicate that the overall flow of the Qingsong area is from north to south and west to east, with a maximum flow of 10–68 m3/s in the north–south backbone, exchange cycle between the backbone river, and the peripheral water bodies in the Qingsong area is 4.3 days. The largest amount of water is diverted along the Wusong River, accounting for 53% of the total water diversion; the drainage mainly relies on the gates along the Huangpu River and the Diandong Pumping Gate, accounting for 43% and 42%, respectively. In view of the lowering of the water level in the slice during the low tide period, an optimal regulation scheme has been developed for more diversion and less drainage along the Huangpu River, which can raise the water level in the slice by 0.05–0.10 m. Assessment and optimization of water resources scheduling in the Qingsong area can provide a reference for hydrodynamic enhancement in the river network area of the tidal plain.

Study On Phytochemical and Antioxidant Properties of Padina gymnospora and Ulva lactuca

Seaweed constitutes one of the commercially important living renewable resources in the marine ecosystem.Seaweeds have antimicrobial, antioxidant, and anti-inflammatory properties. The aim of the study is to estimate the phytochemicals and antioxidant activity of Padina gymnospora and Ulva lactuca. The antioxidant properties and phytochemical analysis of Padina gymnospora and Ulva lactuca collected from the Gulf of Mannar during the low tide period were analyzed.The study's objective is to analyze the phytochemical and antioxidant activities using methanol as solvent. Antioxidant activities were determined using 2,2-diphenyl-1-picryl-hydrazyl (DPPH) assay treated with methanol and Phytochemical analysis carried out by Folin-Ciocalteu reagent. Antioxidants and phytochemicals in seaweeds provide healthpromoting effects and protect against non-communicable diseases such as Cancer, arthritis, diabetes, obesity, etc. The results reveal that antioxidant activities were higher in Padina gymnospora in methanol solvent than in Ulva lactuca. The percentage of inhibition of Padina gymnospora and Ulva lactuca was 61.5 and 64.5 respectively. IC50 value of Padina gymnospora and Ulva lactuca was 60.4 and 60.6 respectively.The preliminary phytochemical analysis of Padina gymnospora and Ulva lactuca was found to contain Alkaloids, Steroids, Terpenoids, Glycosides. To know the efficiency of green seaweed Ulva lactuca with brown seaweed Padina gymnospora the study was carried out. The highest flavonoid content was recorded in brown seaweed Padina gymnospora (25.5±0.02mg REg-1) compared toUlva lactuca (19.32±0.5mg REg-1). The total phenolic content was highest in Padina gymnospora (3.7±0.06mg GAEg-1) whereas Ulva lactuca contained (2.81±0.3mg GAEg-1). Therefore, the present work recommends consuming seaweeds in our regular diets to have a healthy lifestyle. From the current study of phytochemical and antioxidant rich seaweeds can be incorporated in the formulation of drugs used for treating various non- communicable diseases prevailing in the present era. Keywords: , , ,

Apply MIKE 11 model to study impacts of climate change on water resources and develop adaptation plan in the Mekong Delta, Vietnam: a case of Can Tho city.

Can Tho city in the Mekong Delta is in the top ten areas affected by climate change. Therefore, assessing climate change impacts, social and economic activities require proposed solutions to respond to climate change. This study aims to (i) apply the MIKE 11 model (Hydrodynamic module and Advection-Dispersion module) to simulate the impacts of climate change scenarios on water resources in Can Tho city; (ii) calculate water balance in Can Tho city; and (iii) suggest climate change adaptation plan for sustainable social-economic activities of the city. The results show that when the rainfall changes due to climate change, the flow rate tends to decrease at high tide and increase at low tide. When the sea level rises due to climate change, the flow rate tends to increase at high tide and decrease at low tide. For 2030, the flow will decrease up to 15.6% and 14.3% at the low tide period for RCP 2.6 and RCP 8.5 compared to the present, respectively. The flow will increase up to 63.5% and 58.9% at the high tide period for RCP 2.6 and RCP 8.5 compared to the present, respectively. The water demand evaluation shows that the water resource reserve in Can Tho city meets water demands in current and future scenarios under climate change. While rainwater and groundwater can provide enough water in the rainy season, the city has to use surface water during the dry season due to a lack of rainwater. Of these, agriculture contributes the most water demands (85%). Eight adaptation measures to climate change for Can Tho city are developed from 2021 to 2050.

MACROZOOBENTHIC COMMUNITY STRUCTURES IN SEAWEED CULTURE PONDS IN MUARA GEMBONG ESTUARY, BEKASI , WEST JAVA PROVINCE, INDONESIA

The study of macrozoobenthic in seaweed culture in Muara Gembong Estuary, Bekasi District, West Java Province, was conducted in May to July 2018. The study was aimed at understanding the roles of macrozoobenthic organisms as ecosystem engineering in seaweed habitat by identifying macrozoobenthic community structures using various biological indices. Sampling sites were conducted at three selected intertidal ponds used for seaweed culture at different distances and perpendicular to the coastline. Samples of macrozoobenthic organisms were collected using an Ekman grab during low tide periods. The study results showed that the macrozoobenthic community from the three ponds were consisted of 9 major benthic families and 14 genera with a total of 139 individuals. The results also showed that gastropod of the genus Cerithiidae was the dominant taxa found in every pond which contributed to 42.45% of the total macrozoobenthic found in the three ponds and became the main contributing taxa to the macrozoobenthic community structure. In addition, genus Platynereis of the Polychaeta Class was found to be another important taxon which contributed to 14.39% of the total macrozoobenthic found in the three ponds. The genus Platynereis were mostly found in the second pond with muddy coarse sandy sediment substrate containing more silt compared to the other two ponds. The rare taxon was the genus Lithophaga from family Mytilidae represented by 1 individual. Our study concluded that the macrozoobenthic community structure in the three ponds was categorized as poorly diverse indicating that the pond system was unstable. The Shannon-Wiener Diversity Index (H’) was only 0.87 on average with the highest diversity index (H’=1.47) was found in the third pond located at the farthest area of the coastline. Meanwhile, the average of Evenness Index was 0.34 indicating that the distribution of the taxa was uneven with a tendency of being dominated by certain taxa.

First report on the occurrence of pharmaceuticals and cocaine in the coastal waters of Santa Catarina, Brazil, and its related ecological risk assessment.

The worldwide occurrence of pharmaceuticals and personal care products (PPCPs) in aquatic ecosystems is reason for public concern. These emerging micropollutants include a large and diverse group of organic compounds, with continuous input, high environmental persistence and potential threat to biota and human health. The aim of this study was to evaluate, for the first time, the occurrence of twenty-seven PPCPs of various therapeutic classes (including cocaine and its primary metabolite, benzoylecgonine), in the coastal waters of Santa Catarina, southern Brazil. Water samples were taken in November 2020, during the low tide periods, at eight sampling points located along the coast of Santa Catarina, covering its entire geographical extension. Sampling was carried out in triplicate and at different depths of the water column. Nine compounds were detected through liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS): caffeine (12.58-119.80ng/L), diclofenac (1.34-7.92ng/L), atenolol (1.13-2.50ng/L), losartan (0.43-3.20ng/L), acetaminophen (0.21-10.04ng/L), orphenadrine (0.07-0.09ng/L), cocaine (0.02-0.17ng/L), benzoylecgonine (0.01-1.1ng/L) and carbamazepine (0.02-0.27ng/L). The highest occurrence of these compounds was detected in the northern and central coastal region of Santa Catarina, namely in Penha and Palhoça cities. Moreover, the risk assessment showed that almost compounds (atenolol, benzoylecgonine, carbamazepine, cocaine and orphenadrine) presented no ecological risk in the recorded concentrations. However, a few compounds suggest low (caffeine and diclofenac) to moderate (acetaminophen and losartan) risk taking into consideration the acute and chronic effects for the three trophic levels (algae, crustacean and fish) tested. These compounds are usually found in areas with high population density, aggravated by tourism, because of the sanitary sewage and solid waste. Although in low concentrations, the occurrence of these chemical compounds can imply deleterious effects on the environmental health of Santa Catarina coastal zone, and therefore deserve more attention by the public authorities and environmental agencies.