Coastal Organisms Research Articles

Salinity-dependent effects of ZnO nanoparticles on bioenergetics and intermediate metabolite homeostasis in a euryhaline marine bivalve, Mytilus edulis

Engineered nanoparticles including ZnO nanoparticles (nZnO) are important emerging pollutants in aquatic ecosystems creating potential risks to coastal ecosystems and associated biota. The toxicity of nanoparticles and its interaction with the important environmental stressors (such as salinity variation) are not well understood in coastal organisms and require further investigation. Here, we examined the interactive effects of 100 μg l−1 nZnO or dissolved Zn (as a positive control for Zn2+ release) and salinity (normal 15, low 5, and fluctuating 5–15) on bioenergetics and intermediate metabolite homeostasis of a keystone marine bivalve, the blue mussel Mytilus edulis from the Baltic Sea. nZnO exposures did not lead to strong disturbances in energy or intermediate metabolite homeostasis regardless of the salinity regime. Dissolved Zn exposures suppressed the mitochondrial ATP synthesis capacity and coupling as well as anaerobic metabolism and modified the free amino acid profiles in the mussels indicating that dissolved Zn is metabolically more damaging than nZnO. The environmental salinity regime strongly affected metabolic homeostasis and altered physiological and biochemical responses to nZnO or dissolved Zn in the mussels. Exposure to low (5) or fluctuating (5–15) salinity affected the physiological condition, energy metabolism and homeostasis, as well as amino acid metabolism in M. edulis. Generally, fluctuating salinity (5–15) appeared bioenergetically less stressful than constantly hypoosmotic stress (salinity 5) in M. edulis indicating that even short (24 h) periods of recovery might be sufficient to restore the metabolic homeostasis in this euryhaline species. Notably, the biological effects of nZnO and dissolved Zn became progressively less detectable as the salinity stress increased. These findings demonstrate that habitat salinity must be considered in the biomarker-based assessment of the toxic effects of nanopollutants on coastal organisms.

Heavy metal and organic load in Haripur creek of Gopalpur along the Bay of Bengal, east coast of India.

Accumulation of heavy metals in zooplanktons is used as an essential tool for the evaluation of health of an ecosystem. Such data are used to set further monitoring strategies especially in (coastal) water bodies. In the present study, seasonal bioaccumulation of heavy metals such as Cu, Zn, Pb, Cd and Hg, organic loads such as nitrite and phosphate, contents loads and physicochemical parameters in Haripur creek along the Bay of Bengal in east coast of India is measured in zooplanktons. Coastal organisms are considered an integral part of marine ecosystems and their frequent massive die-off events along the coast of the Bay of Bengal are correlated with the obtained pollutant data. The levels of heavy metals were also correlated with several extrinsic environmental factors such as water transparency, dissolved oxygen, salinity, pH and temperature. Discriminant function analyses and standardised coefficients for canonical variables for the obtained data indicate that the studied environmental factors and organic loads varied as a function of season. Bioaccumulation of the studied heavy metals in zooplanktons was seasonal and infrequently noticed above the standard limit. The computed bioaccumulation factor of the five metals showed that accumulation of Zn was higher in zooplanktons as compared to that of the other studied metals. So, the entry of heavy metals through the food chains or via direct exposure (to organic loads also) to the other inhabiting organisms including fish may be assumed. This could be one of the possible reasons for the observed frequent (fish) die-off events at Gopalpur Coast along the Bay of Bengal and may be considered a clue for future investigations.

Ontology-Assisted Expert System for Algae Identification With Certainty Factors

Harmful algal blooms (HABs) are one of nature’s responses to nutrient enrichment in aquatic systems and increasingly occur in coastal waters, such as in Lampung Bay and Jakarta Bay, Indonesia. HABs present environmental and fisheries management challenges due to their unpredictability, spatial coverage, and detrimental health effects on coastal organisms, including humans. Here, an automated algae species identification system assisted and validated by expert judgment was proposed. The system used ontology as guidance to determine the species of algae and certainty factors to indicate the level of confidence of the experts when providing a statement or judgment for a particular object or event under consideration. The system was tested to identify 60 samples using 51 predetermined algal characteristics. The tests were narrowed down to the 20 most common HAB-causing algae types found in the study sites and compared with identification by experts. The results showed that the system successfully identified the test data with an accuracy of 73.33%. The system also had a high agreement (above 79.75%) with the identification performed by experts on six algae species. Further improvement of the system’s accuracy could facilitate its use as an alternative tool in rapid algal identification or part of an early warning system for HABs.

Elevated temperatures increase growth and enhance foraging performances of a marine gastropod

The oceans continue to warm due to rising atmospheric greenhouse gas concentrations. Most climate-change studies of aquaculture species use temperature changes based on coarse-resolution climate models and without considering thermal ranges of an animal. Coarse-resolution climate models are generated by global-scale data, which is insufficient to capture the conditions of coastal areas where most aquaculture activity occurs. Therefore, ocean warming research on coastal organisms requires a more comprehensive design to include broad temperature gradients. By using the ecologically and commercially important coastal whelk Rapana venosa, we combined long-term and short-term experiments and selected 4 temperature treatments (19, 23, 27, and 30°C) to simulate different scenarios to test ocean warming effects on growth rates and foraging performances of whelks. We found that elevated temperature within the whelk’s thermal range (23 and 27°C) significantly increased growth rates and enhanced foraging performances of marine whelks when compared to the current temperature (19°C). Conversely, the whelk’s performance collapsed at 30°C in terms of both growth and foraging behavior. Our research clearly shows that local conditions and the tolerance range of a species must be considered to develop meaningful information for testing the effects of a changing climate. Our study suggests that rapa whelks may increase their feeding and reach larger sizes during warmer periods. Moreover, our study may provide a foundation for future climate research on aquaculture species.

Using ultraconserved elements to track the influence of sea-level change on leafy seadragon populations.

During the Last Glacial Maximum (LGM), global sea levels were 120-130m lower than today, resulting in the emergence of most continental shelves and extirpation of subtidal organisms from these areas. During the interglacial periods, rapid inundation of shelf regions created a dynamic environment for coastal organisms, such as the charismatic leafy seadragon (Phycodurus eques, Syngnathidae), a brooder with low dispersal ability inhabiting kelp beds in temperate Australia. Reconstructions of the palaeoshoreline revealed that the increase of shallow areas since the LGM was not uniform across the species' range and we investigated the effects of these asymmetries on genetic diversity and structuring. Using targeted capture of 857 variable ultraconserved elements (UCEs, 2,845 single nucleotide polymorphisms) in 68 individuals, we found that the regionally different shelf topographies were paralleled by contrasting population genetic patterns. In the west, populations may not have persisted through sea-level lows because shallow seabed was very limited. Shallow genetic structure, weak expansion signals and a westward cline in genetic diversity indicate a postglacial recolonization of the western part of the range from a more eastern location following sea-level rise. In the east, shallow seabed persisted during the LGM and increased considerably after the flooding of large bays, which resulted in strong demographic expansions, deeper genetic structure and higher genetic diversity. This study suggests that postglacial flooding with rising sea levels produced locally variable signatures in colonizing populations.

Effects of short-term and continuous exposure to reduced salinities on the biochemical composition of larval lobster, Homarus gammarus

In coastal areas with estuarine influence, exposure to hypo-osmotic conditions may affect larval survival, development and growth. Most knowledge about effects of reduced salinity on coastal organisms is based on keeping individuals under constant conditions in the laboratory. By contrast, little is known about the effects of more realistic situations where organisms are exposed to low salinity over short time scales. Such environmental short-term fluctuations are expected to increase due to climate change. Here, we experimentally evaluated the sublethal effects of both short-term and continuous exposure to moderately reduced salinities (salinity 20 and 25; compared to seawater, salinity 32) in larvae of European lobster Homarus gammarus. Total body dry mass and biochemical composition (measured as: protein and lipid contents) were measured as response variables in Mysis stages I to III. Short-term effects of low salinity were quantified in a group of larvae kept in seawater from hatching until the time of transfer to the test salinities. After ca. 40 % of each moult cycle in seawater (determined in preliminary experiments for Mysis I, II and III), larvae were assigned to a seawater control or reduced salinities lasting for 16 h (i.e. until ca. 50 % of the time spent within the moulting cycle). Effects of continuous exposure to low salinity were quantified when larvae were exposed to the different salinities from hatching, until they reached ca. 50 % of the successive moulting stage. Surprisingly, in the Mysis II and III stages, short-term exposure to low salinity had much stronger effects on accumulation of reserves than the continuous exposure. Such effects were manifested mostly as limited accumulation, or even losses, in the lipid content as compared to reductions in the amount of protein accumulated. The most sensitive stage to exposure to low salinity was the Mysis III; by contrast in Mysis I such effects were relative weak (not always significant). Chronic exposure to low salinity also led to an increase in developmental time especially at the advanced stages. Our results highlight the importance of quantifying effects of environmental fluctuations at different time scales in order to better understand how organisms cope with realistic environmental change in the coastal zones. For H. gammarus, our results suggest that larvae respond adaptively to low salinity by maintaining protein levels at expenses of reductions in lipid accumulation and by extending the developmental time, but the capacity to elicit a fully compensatory response varies ontogenetically.

How do life-history traits influence the fate of intertidal and subtidal Mytilus galloprovincialis in a changing climate?

Coastal organisms (i.e. intertidal or upper subtidal species) live in between the terrestrial and aquatic realms, making them particularly vulnerable to climate change. In this context, intertidal organisms may suffer from the predicted sea level rise (increasing their submerged time) while subtidal organisms may suffer from anthropically-induced hypoxia and its consequences. Although there is some knowledge on how coastal organisms adapt to environmental changes, the biochemical and physiological consequences of prolonged submergence periods have not yet been well characterized. Thus, the present study aimed to assess the biochemical alterations experienced by intertidal organisms maintained always under tidal exposure (IT); intertidal organisms maintained submersed (IS); subtidal organisms maintained always submersed (SS); subtidal organisms under tidal exposure (ST). For this, Mytilus galloprovincialis specimens from contiguous intertidal and subtidal populations were exposed to the above mentioned conditions for twenty-eight days. Results indicated that both intertidal and subtidal mussels are adapted to the oxidative stress pressure caused by tidal and submerged conditions tested. Intertidal mussels did not seem to be negatively affected by submergence while ST specimens were energetically challenged by tidal exposure. Both IT and ST mussels consumed glycogen to fuel up mechanisms aiming to maintain redox homeostasis. Overall, both intertidal and subtidal populations were capable of coping with tidal exposure, although the strategies employed differed between them. These findings indicate that although IT mussels may not significantly suffer from the longer-term submergence, hypoxic events occurring in the context of global warming and other anthropogenic impacts may have consequences on both IT and ST populations. Altogether, it is important to highlight that tides may act as a confounding factor in experiments concerning coastal organisms, as it causes additional physiological and biochemical perturbations.

Marine and coastal organisms: a source of biomedically relevant dipeptidyl peptidase IV inhibitors

Dipeptidyl peptidase IV (DPP-IV, EC 3.4.14.5), also known as CD26, is a serine aminopeptidase that preferentially cleaves Xaa-Pro or Xaa-Ala dipeptides from the N-terminus of peptides leading to their biological activation or inactivation. The enzyme is an homodimer and each subunit is formed by an αβ-hydrolase domain and a β-propeller domain. It has an important role in multiple physiological functions, including the regulation of glucose metabolism, being one of the current targets for the treatment of type 2 diabetes mellitus. It is also up-regulated in rheumatoid arthritis, psoriasis, colitis, multiple sclerosis and transplant rejection. This enzyme also regulates immune system responses mediated by CD4+ T lymphocytes; furthermore, DPP-IV activity is dysregulated in pathologies like thyroid, ovarian, lung, skin, prostate cancers and central nervous system tumors. In clinical practice, DPP-IV inhibitors have several beneficial effects such as anti-hyperglycemia and pancreatic islet protection, immune regulation, cardiovascular and renal protection, anticancer effects, and anti-inflammation. Thus, this enzyme evolved as a target of attention for the development of more efficient pathology diagnostics, and for the development of inhibitors to treat type 2 diabetes mellitus and cancer. Marine and coastal organisms are an abundant source of different bioactive molecules including peptidases and peptidases inhibitors of almost all mechanistic classes, being serine class the most studied. In the present contribution, we review the strategies used to identify and characterize DPP-IV inhibitors from marine and coastal organisms. We show that marine biodiversity is an important, promising, and still unexplored source of inhibitors of dipeptidyl peptidase IV, which may have biomedical applications in human diseases.

Tides: A key environmental driver of osteichthyan evolution and the fish-tetrapod transition?

Tides are a major component of the interaction between the marine and terrestrial environments, and thus play an important part in shaping the environmental context for the evolution of shallow marine and coastal organisms. Here, we use a dedicated tidal model and palaeogeographic reconstructions from the Late Silurian to early Late Devonian (420 Ma, 400 Ma and 380 Ma, Ma = millions of years ago) to explore the potential significance of tides for the evolution of osteichthyans (bony fish) and tetrapods (land vertebrates). The earliest members of the osteichthyan crown-group date to the Late Silurian, approximately 425 Ma, while the earliest evidence for tetrapods is provided by trackways from the Middle Devonian, dated to approximately 393 Ma, and the oldest tetrapod body fossils are Late Devonian, approximately 373 Ma. Large tidal ranges could have fostered both the evolution of air-breathing organs in osteichthyans to facilitate breathing in oxygen-depleted tidal pools, and the development of weight-bearing tetrapod limbs to aid navigation within the intertidal zones. We find that tidal ranges over 4 m were present around areas of evolutionary significance for the origin of osteichthyans and the fish-tetrapod transition, highlighting the possible importance of tidal dynamics as a driver for these evolutionary processes.

Fatty acid compositions of four benthic species along the salinity gradient of a human impacted and mangrove dominated tropical estuary (Can Gio, Vietnam)

Tropical estuaries are characterised by high spatial and temporal variability in the conditions they provide for living organisms, which in turn may affect their biochemical composition. Anthropogenic contaminants such as nutrients, antibiotics, pesticides and trace metals may also affect the biochemical composition of these coastal organisms, notably with regard to fatty acids (FA), of which optimal species-specific polyunsaturated FA ratios are required to maintain living species in healthy conditions. The objective of this study was to evidence changes in the FA profile of four ubiquist benthic species in relation to the salinity gradient of a human impacted and mangrove dominated tropical estuary (Can Gio, Southern Vietnam). Among the four benthic species studied, two exhibited spatial and seasonal changes in their FA composition: the varunid crab Metaplax elegans and the predatory mangrove murex snail Chicoreus capucinus. Proportions of the FA 16:1ω7, proportions of highly unsaturated FA and ratios of eicosapentanoic acid/arachidonic acid in the tissues of both species seemed related to upstream inputs. Different relative abundances of benthic microalgae affected both claw muscle and hepatopancreas FA composition of M. elegans, while the FA composition of C. capucinus shows that the influence of prey's diet might be transferred within trophic chains. Finally, some species, such as Nerita balteata and Metapenaeus ensis might have more adaptive capacities, because of their mobility, or because of their specific metabolic pathways, minimizing the potential impact of spatial and/or temporal changes in food resources quality. A starvation experiment involving N. balteata actually revealed the metabolic synthesis of non-methylene interrupted FA that may confer cell membranes a higher resistance to external stressors than common polyunsaturated FA. Our study highlights the future possibility of using the FA composition of sentinel organisms (i.e. feeding on specific food resources and/or especially subject to environmental stresses) as a bioindicator tool to assess mangrove ecosystems health.

Is hull cleaning wastewater a potential source of developmental toxicity on coastal non-target organisms?

Chemical contaminants can be discharged by vessel hull cleaning processes, such as scraping, jet spraying, and painting, all of which produce readily transportable contaminants into the marine environment, where they are referred to as ‘hotspots’ of contamination in coastal areas. However, many countries have not yet established effective evaluation methods for disposal of waste mixtures or management guidelines for areas of hull cleaning. To define the toxic effects of wastewater from vessel hull cleaning in dry docks on resident non-target organisms, we investigated the chemical concentrations and developmental toxicity on embryonic flounder, which is an organism sensitive to chemical contamination. In this study, the dominant inorganic metal discharged was zinc when cleaning Ship A (300 tons) and copper for Ship B (5,000 tons). The wastewater from high-pressure water blasting (WHPB) of Ship A (300 tons) and Ship B (5,000 tons) produced a largely overlapping suite of developmental malformations including pericardial edema, spinal curvature, and tail fin defects. Forty-eight hours after exposure, the frequency percentage of malformation began to increase in embryos exposed to a 500-fold dilution of WHPB from Ships A and B. We performed transcriptome sequencing to characterize the toxicological developmental effects of WHPB exposure at the molecular level. The results of the analysis revealed significantly altered expression of genes associated with muscle cell differentiation, actin-mediated cell contraction, and nervous system development (cutoff P < 0.01) in embryonic flounder exposed to high-pressure cleaning effluent from Ship A. Genes associated with chromatin remodeling, cell cycling, and insulin receptor signaling pathways were significantly altered in embryonic flounder exposed to WHPB of Ship B (cutoff P < 0.01). These findings provide a greater understanding of the developmental toxicity and potential effects of WHPB effluent on coastal embryonic fish. Furthermore, our results could inform WHPB effluent management practices to reduce impacts on non-target coastal organisms.

Complex phylogeographic patterns in the intertidal goby Chaenogobius annularis around Kyushu Island as a boundary zone of three different seas

Paleoenvironmental changes in marginal seas on the coast of the northwestern Pacific during the Quaternary have caused genetic differentiation and subsequent secondary contacts between populations of coastal organisms in this region. However, little is known about how geographical isolation and the subsequent connection events associated with these multiple marginal seas have shaped the population structure of coastal organisms in the boundary area. The coastal area of Kyushu Island of the Japanese Archipelago, where the East China Sea (ECS), the Sea of Japan (SJ), and the Pacific Ocean (PO) adjoin within a narrow region, would be a suitable field for elucidating the effect of multiple vicariances. Herein, we conducted phylogeographical analyses of the intertidal goby Chaenogobius annularis, focusing on populations around Kyushu Island, using partial mitochondrial (mt) DNA sequences and analysis of 8 microsatellite (ms) DNA loci. We discovered a new lineage distributed along the coast of the ECS distinct from the already-known SJ and PO lineages, which we termed the ECS lineage. This ECS lineage showed remarkable mito-nuclear discordance: mtDNA analyses indicated that the ECS lineage is a highly diverged lineage branched from the PO lineage, whereas msDNA analyses suggested that the ECS lineage is closely related to the SJ lineage. This discordance could have been due to ancient hybridization. In addition, we detected SJ-PO and ECS-SJ hybrid zones on the western Seto Inland Sea and on the northwestern coast of Kyushu, respectively. Such a complex population structure suggests that the secondary contacts after multiple isolation events among marginal seas around Kyushu have a great impact on coastal biodiversity in the area and emphasize the peculiarities of the region.

Amazon river plume influence on planktonic decapods in the tropical Atlantic

The western tropical Atlantic is strongly influenced by the Amazon, receiving the full discharge from the largest river basin of the world. In order to ascertain the coastal-oceanic gradient in abundance and composition of planktonic decapod communities along the Amazon River Plume (ARP) and its retroflection, 33 plankton samples were obtained along three sampling transects: Coastal and oceanic area influenced by the ARP (Coastal IARP and Ocean IARP, respectively), and oceanic waters without ARP influence (Ocean). A total of 13,117 specimens, belonging to 33 taxa, were analyzed. The distribution of planktonic decapod communities was strongly influenced by the Amazon discharge, showing the following patterns: (1) The coastal-oceanic gradients in decapod abundance are similar to other shelf areas of eastern South America, with higher abundance in the area under ARP influence, (2) meroplanktonic decapods dominate in coastal and some oceanic areas due to the offshore transport of coastal organisms along the ARP retroflection, and (3) the ARP is clearly responsible for the observed differences in community structure between the three transects. Furthermore, this study highlights the importance of coastal and shelf environments as main sources of planktonic decapods for pelagic ecosystems in the tropical Atlantic during the period of strong North Brazil Current retroflection.

Season-dependent effects of ZnO nanoparticles and elevated temperature on bioenergetics of the blue mussel Mytilus edulis

Input of ZnO nanoparticles (nZnO) from multiple sources have raised concerns about the potential toxic effects on estuarine and coastal organisms. The toxicity of nZnO and its interaction with common abiotic stressors (such as elevated temperature) are not well understood in these organisms. Here, we examined the bioenergetics responses of the blue mussel Mytilus edulis exposed for 21 days to different concentrations of nZnO or dissolved zinc (Zn2+) (0, 10, 100 μg l−1) and two temperatures (ambient and 5 °C warmer) in winter and summer. Exposure to nZnO had little effect on the protein and lipid levels, but led to a significant depletion of carbohydrates and a decrease in the electron transport system (ETS) activity. Qualitatively similar but weaker effects were found for dissolved Zn. In winter mussels, elevated temperature (15 °C) led to elevated protein and lipid levels increasing the total energy content of the tissues. In contrast, elevated temperature (20 °C) resulted in a decrease in the lipid and carbohydrate levels and suppressed ETS in summer mussels. These data indicate that moderate warming in winter (but not in summer) might partially compensate for the bioenergetics stress caused by nZnO toxicity in M. edulis from temperate areas such as the Baltic Sea.

Season specific influence of projected ocean changes on the response to cadmium of stress-related genes in Mytilus galloprovincialis

Anthropogenic inputs of carbon dioxide in the atmosphere are driving ocean warming and acidification. The potential threat represented by these changes for marine species could be amplified in coastal areas, characterized by higher levels of pollutants. In addition, temperate organisms may exhibit a different seasonal tolerance to stressors influenced by fluctuations of environmental and physiological factors. In this study, Mediterranean mussels Mytilus galloprovincialis collected both in summer and winter were exposed to combinations of two temperatures (SST, seasonal surface temperature and SST+5 °C) and two levels of pH (8.20 and 7.40) in clean or cadmium contaminated seawater (20 μg/L Cd). mRNA levels of genes related to metal-induced stress response were investigated, including metallothionein mt-20, heat-shock protein hsp70, superoxide dismutase Cu/Zn-sod, catalase cat, glutathione peroxidase gpx1 and glutathione S-transferase gst-pi. To further elucidate if tissues with different physiological roles could exhibit different responsiveness, such analyses were carried out in digestive gland and in gills of exposed mussels. mt-20 mRNA increase after Cd-exposure was higher in the digestive gland than in the gills, with few modulations by temperature or pH only in the latter. Acidification, alone or in combination with other stressors, increased hsp70 mRNA, with seasonal- and tissue-specificities (higher in summer and in digestive gland). Among antioxidants, gpx1 mRNA was affected by Cd in both tissues and seasons, with further modulations due to pH and temperature variation tissue- and season-specific; in winter the combination of Cd, warming and acidification affected Cu/Zn-sod both in digestive gland and gills and cat only in gills, while weak seasonal variations were observed for gst-pi transcripts only in digestive gland. The overall results highlighted the importance of considering seasonality and responsiveness of different tissues to predict the effects of sudden changes in environmental parameters on responsiveness to and toxicity of chemicals in marine coastal organisms.

Trophodynamics of arsenic for different species in coastal regions of the Northwest Pacific Ocean: In situ evidence and a meta-analysis

China has been the major fishery producer in the Northwest Pacific Ocean for decades and the seafood safety deserves continuous concern. In this study, 188 organism and 27 sediment samples were collected from the Jiaozhou Bay, a typical semi-enclosed bay adjacent to the Northwest Pacific Ocean, to study the arsenic (As) pollution level and trophodynamics in the coastal regions of China combined with a meta-analysis. Results showed that arsenic was the most abundant in crustaceans with the average of 28.84 ± 4.95 mg/kg in dry weight, in comparison with molluscs (18.68 ± 2.51 mg/kg) and fish (9.31 ± 1.45 mg/kg). Additionally, based on a meta-analysis, arsenic in coastal organisms generally decreased from north to south in China. With increasing values of δ15N, arsenic was significantly biomagnified in the molluscs but bio-diluted in the groups of crustaceans and fish. When all the species were taken into consideration, overall bio-dilution of As was observed through the simplified food chain in the Jiaozhou Bay. Based on the target hazard quotient (THQ), the health risk of consuming seafood from the Jiaozhou Bay was not significant except for several kinds of crustaceans. The smaller THQs indicated lower health risk of eating molluscs and fish than crustaceans. Besides, urban households tended to undertake much higher risk than rural households. Based on our results, it is recommended for urban citizens to reduce the frequency of consuming crustaceans and give preference to fish when choosing seafood.

Mechanism of species dynamics and interactions under impacts of artificial barriers in coastal areas

Coastal reclamation engineering structures are exerting significant isolation effects on dynamics of local species. In this research, a population dynamics model was developed for investigating and analyzing dispersal patterns under isolation of artificial barriers in coastal areas. The proposed model have the following advantages: a) revelation of responses for population dynamics under multiple types of artificial barriers; b) reflection a general link between species predation, competition and density-dependent population growth under pressure of artificial barriers. Three barrier types including dotted distribution (DD), linear distribution (LD) and facet distribution (FD) were analyzed and discussed. As the results, the population decline rate for FD would be 10.22% higher than that for LD. The LD could be conducive to protecting the ecological balance of coastal organisms. Based on satisfying the requirements of coastline protection, LD would be an important reference for coastal engineering design and management in future.

Diel and tidal pCO2\u2009\xd7\u2009O2 fluctuations provide physiological refuge to early life stages of a coastal forage fish

Coastal ecosystems experience substantial natural fluctuations in pCO2 and dissolved oxygen (DO) conditions on diel, tidal, seasonal and interannual timescales. Rising carbon dioxide emissions and anthropogenic nutrient input are expected to increase these pCO2 and DO cycles in severity and duration of acidification and hypoxia. How coastal marine organisms respond to natural pCO2 × DO variability and future climate change remains largely unknown. Here, we assess the impact of static and cycling pCO2 × DO conditions of various magnitudes and frequencies on early life survival and growth of an important coastal forage fish, Menidia menidia. Static low DO conditions severely decreased embryo survival, larval survival, time to 50% hatch, size at hatch and post-larval growth rates. Static elevated pCO2 did not affect most response traits, however, a synergistic negative effect did occur on embryo survival under hypoxic conditions (3.0 mg L−1). Cycling pCO2 × DO, however, reduced these negative effects of static conditions on all response traits with the magnitude of fluctuations influencing the extent of this reduction. This indicates that fluctuations in pCO2 and DO may benefit coastal organisms by providing periodic physiological refuge from stressful conditions, which could promote species adaptability to climate change.

Multimedia distributions, bioaccumulation, and trophic transfer of microcystins in the Geum River Estuary, Korea: Application of compound-specific isotope analysis of amino acids

To determine distributions, bioaccumulation, and trophic transfer of freshwater cyanobacterial toxins such as microcystins (MCs), surface water, suspended solids, sediments, and coastal organisms were collected from seven stations in inner and outer regions of the estuary dam in the Geum River Estuary in June and July 2017. Concentrations of MC variants (MC-LR, -RR, and -YR) in the multimedia samples were analyzed using a HPLC-MS/MS. Trophic position (TP) of organisms (fish, bivalve, gastropod, decapod, and polychaete) was determined by nitrogen stable isotope analyses of both bulk tissues and amino acids. From July to August 2017, great concentrations of MCs were detected in discharged freshwater ranging from 0.4 to 75 μg L−1. Considerable amounts of MCs are delivered to the Geum River Estuary in summer season. MCs spread far away as dissolved phases (18.7–49.5 ng L−1) in July when large amount of freshwater was discharged during the rainy season. Concentrations of MCs in marine organisms varied among species, ranging from 40 to 870 ng g−1 dw. Bioaccumulated MCs tend to decrease with increasing TP of organisms, suggesting that MCs are biodiluted through the marine food web. Compound-specific isotope analysis (nitrogen of amino acids) provides more reliable TPs compared with those by bulk isotope analysis in a closed estuary (such as the Geum River Estuary) with large fluctuations in the isotope ratio of primary producers.

Shoreline Movement Monitoring and Geomorphologic Changes of Beaches Using Lidar and UAVs Images on the Coast of the East Sea, Korea

Lee, Y.K.; Eom, J.; Do, J.D.; Kim, B.J., and Ryu, J.H., 2019. Shoreline movement monitoring and geomorphologic changes of beaches using lidar UAVs images on the coast of the East Sea, Korea. In: Jung, H.S.; Lee, S.; Ryu, J.H., and Cui, T. (eds.), Advances in Remote Sensing and Geoscience Information Systems of Coastal Environments. Journal of Coastal Research, Special Issue No. 90, pp. 409-414. Coconut Creek (Florida), ISSN 0749-0208.Sandy beaches are important habitats for coastal organisms and act as buffer zones during coastal disasters. Most of the coastal zone along the eastern coast of Korea consists of sandy beaches. However, beach erosion has been accelerating in recent years. In this study, shoreline movement and topographical changes were analyzed in Uljin-gun on the East Sea coast of Korea using remotely sensed data from airborne Lidar and unmanned aerial vehicles (UAVs). The shoreline changes extracted were statistically quantified using net shoreline movement (NSM) and linear regression rate (LRR) in the digital shoreline analysis system (DSAS). Morphological changes were quantified based on a comparison of the digital surface maps (DSM) generated by Lidar and UAVs. Shoreline movement and morphological changes were analyzed over the short-term (February 2016 to February 2019) and long-term (June 2008 to June 2018). Seaward migration was dominant for 7.02 m, 1.64 m, and 9.22 m along three defined subareas over the long-term. Over the short-term, LRR results showed landward migration as 0.7 m and 1.10 m in two of the subareas. Morphological change showed erosion and accretion occurring at approximately 0.08 m3 and 0.42 m3, respectively. This reverse trend indicates that a detailed DSM can detect volumetric change due to relocation of the sediment around artificial construction.