Marine Aquatic Ecosystems Research Articles

From cosmetics to Contamination: Microplastics in personal care products as vectors for chromium in aquatic environments

Microplastics presence in the environment is now a major global issue. Personal care and cosmetic products (PCCPs) contain microbeads and are one of the primary sources of microplastics which contribute to health and ecological risks. The aim of this study was to evaluate the presence of microbeads in a widely used PCCPs (facial scrubs) in the Indian market and the extent to which these microbeads can serve as vectors for toxic compounds like chromium under different environmental conditions. Four of the ten facial scrubs contained microbeads of size ranging from 220 to 600 µm. Based on FTIR analyses, two of the four tested samples (A and B) were made of polypropylene, while the other two samples (C and D) were made of polyethylene. Furthermore, the study revealed that PP microbeads, which are very common, could efficiently adsorb Cr (VI) (3.09 mg Cr/g). Adsorption of Cr (VI) on microbeads was greater in acidic and saline conditions indicating that microbeads can potentially act as vectors for toxic compounds in marine aquatic ecosystems. It was estimated that 4.7 x 1010 microbeads, which amount to 3.8 tonnes of microbeads are released into the environment annually. Based on these results, policy measures for preventing the release of microbeads/microplastics into the environment are suggested.

The estimated environmental impact on the distribution, mass and abundance of plastics in aquatic ecosystems

Plastic began to be manufactured on a commercial scale in the 1950s, and people saw its attractive properties as revolutionary. Plastic has proven to be a very attractive product because it is lightweight, water resistant, heat and electric insulating and extremely durable. It is also very cheap to make. The starting ingredient is the less commonly killed organic raw material of petroleum, natural gas, or plant material - an increasingly attractive option as the rage for fossil fuels grows. Consequently, plastic can remain for hundreds of years up to 400 years for its degradability in the environment (unless recycled or incinerated). More than a third of plastic is manufactured for single use, most of which is disposed of in the environment within one year of manufacture. In particular, about 8 million tons enter the oceans each year. The durable nature of plastic is remarkable because even though it is made of organic matter, living things cannot digest and break it - a stark contrast to the waste of food and paper. Plastic debris can be distinguished into macroplastics and microplastics. Furthermore, exposure to heat an solar UV radiation makes the fragments brittle so that they easily crumble producing secondary microplastics forming persistent organic pollutants. In addition, there is a sizable fraction of primary microplastics, e.g. microbeads. These pollutants are found in terrestrial and marine aquatic ecosystems and are considered a serious problem of high environmental impact.

Bioaccumulation of polystyrene microplastics and changes in antioxidant and AChE pattern in a freshwater snail (Filopaludina bengalensis) from river Ganga

Microplastic pollution is a leading global problem affecting terrestrial and marine aquatic ecosystems. Due to the stagnant nature of microplastics, the toxic effect of microplastics is more pronounced to benthic organisms than the surface feeder. Hence, the present study effort was to study the microplastic bioaccumulation pattern and changes in the enzymatic and nonenzymatic antioxidant and AChE pattern of freshwater snail Filopaludina bengalensis, which were subjected to 0.5 ppm to 5 ppm levels of polystyrene microsphere (∼ 30 µm) for 27 days. The study showed that microplastics were easily accumulated in the test organism in a dose and time-dependent manner, amounting to 82 ± 6.02 particles /individuals at a 5 ppm dose on the 27th day. However, no mortality was observed at the test microplastic dosages. The enzymatic antioxidant profile (SOD and catalase) showed limited variability and remained stable with increased duration and microplastic dose. However, the nonenzymatic antioxidant profile showed distinct variability with the complete seizing of the DPPH activity on the 27th day at 5 ppm microplastic dose and a gradual decrease of ABTS and FRAP activity at all the dose ranges. Even the AChE activity decreased with higher exposure concentrations. The present study for the first time shows the direct impact of microplastics on a freshwater snail widely available in the Indian subcontinent, indicating the role of microplastic pollution will create havoc in the Ganga river eco-biosystem in the long run.

Characterization of cellular toxicity induced by sub-lethal inorganic mercury in the marine microalgae Chlorococcum dorsiventrale isolated from a metal-polluted coastal site

Mercury (Hg) is a global pollutant that affects numerous marine aquatic ecosystems. We isolated Chlorococcum dorsiventrale Ch-UB5 microalga from coastal areas of Tunisia suffering from metal pollution and analyzed its tolerance to Hg. This strain accumulated substantial amounts of Hg and was able to remove up to 95% of added metal after 24 and 72 h in axenic cultures. Mercury led to lesser biomass growth, higher cell aggregation, significant inhibition of photochemical activity, and appearance of oxidative stress and altered redox enzymatic activities, with proliferation of starch granules and neutral lipids vesicles. Such changes matched the biomolecular profile observed using Fourier Transformed Infrared spectroscopy, with remarkable spectral changes corresponding to lipids, proteins and carbohydrates. C. dorsiventrale accumulated the chloroplastic heat shock protein HSP70B and the autophagy-related ATG8 protein, probably to counteract the toxic effects of Hg. However, long-term treatments (72 h) usually resulted in poorer physiological and metabolic responses, associated with acute stress. C. dorsiventrale has potential use for Hg phycoremediation in marine ecosystems, with the ability to accumulating energetic reserves that could be used for biofuel production, supporting the notion of using of C. dorsiventrale for sustainable green chemistry in parallel to metal removal.

“Non-traditional” stable isotopes applied to the study of trace metal contaminants in anthropized marine environments

The advent of Multicollector ICP-MS inaugurated the analysis of new metal isotope systems, the so-called “non-traditional” isotopes. They are now available tools to study geochemical and ecotoxicological aspects of marine metal contamination and hence, to push the frontiers of our knowledge. However, such applications are still in their infancy, and an accessible state-of-the-art describing main applications, obstacles, gaps, and directions for further development was missing from the literature. This paper fills this gap and aims to encourage the marine scientific community to explore the contributions of this newly available information for the fields of chemical risk assessment, biomonitoring, and trophic transfer of metal contaminants. In the current “Anthropocene” epoch, metal contamination will continue to threaten marine aquatic ecosystems, and “non-traditional” isotopes can be a valuable tool to detect human-induced changes across time-space involving metal contaminants, and their interaction with marine biota.

Life in a drop: Sampling environmental DNA for marine fishery management and ecosystem monitoring

Science-based management of marine fisheries and effective ecosystem monitoring both require the analysis of large amounts of often complex and difficult to collect information. Legislation also increasingly requires the attainment of good environmental status, which again demands collection of data to enable efficient monitoring and management of biodiversity. Such data is traditionally obtained as a result of research surveys through the capture and/or visual identification of organisms. Recent years have seen significant advances in the utilisation of environmental DNA (eDNA) in the marine environment in order to develop alternative cost-effective ways to gather relevant data. Such approaches attempt to identify and/or quantify the species present at a location through the detection of extra-organismal DNA in the environment. These new eDNA based approaches have the potential to revolutionise data collection in the marine environment using non-invasive sampling methods and providing snapshots of biodiversity beyond the capacity of traditional sampling. Here we present a non-technical summary of different approaches in the field of eDNA, and emphasise the broad application of this approach, with value for the governance and management of marine aquatic ecosystems. The review focuses on identifying those tools which are now readily applicable and those which show promise but are currently in development and require further validations. The aim is to provide an understanding of techniques and concepts that can be used by managers without genetic or genomic expertise when consulting with specialists to perform joint evaluations of the utility of the approaches.

Mycobacteriosis in Aquatic Invertebrates: A Review of Its Emergence.

Mycobacteriosis is a chronic bacterial disease reported in aquatic and terrestrial animals, including humans. The disease affects a wide range of cultured and wild organisms worldwide. Mycobacteriosis is well-known in aquatic vertebrates (e.g., finfish, marine mammals), while in the last few years, reports of its presence in aquatic invertebrates have been on the rise, for both freshwater and marine species. The number of cases is likely to increase as a result of increased awareness, surveillance and availability of diagnostic methods. Domestication of wild aquatic species and the intensification of modern aquaculture are also leading to an increase in the number of reported cases. Moreover, climate changes are affecting fresh and marine aquatic ecosystems. The increasing reports of mycobacteriosis in aquatic invertebrates may also be influenced by global climate warming, which could contribute to the microbes’ development and survival rates, pathogen transmission and host susceptibility. Several species of the genus Mycobacterium have been diagnosed in aquatic invertebrates; a few of them are significant due to their wide host spectrum, economic impact in aquaculture, and zoonotic potential. The impact of mycobacteriosis in aquatic invertebrates is probably underestimated, and there is currently no effective treatment other than facility disinfection. In this review, we provide an overview of the diversity of mycobacterial infections reported in molluscs, crustaceans, cnidarians, echinoderms and sponges. We highlight important issues relating to its pathological manifestation, diagnosis and zoonotic considerations.

Bioaccumulation of heavy metals in edible marine fish from coastal areas of Nellore, Andhra Pradesh, India

The worldwide increase in population, urbanization, and industrialization was affecting the natural aquatic environment in the form of pollution. The consumption of fishes as food has immense therapeutic and nutritional benefits. Heavy metal pollution of marine aquatic ecosystem occurring due to urban and industrial waste discharge, agricultural runoff and accidental spills of toxic chemicals is globally a rising concern and possesses a dangerous threat for human health due to their regular feeding habits. Humans consume fish as a dietary uptake without knowing the heavy metal accumulated from the polluted areas and are vulnerable to certain health risks. An attempt was made in the present investigation to monitor heavy metals concentration in coastal waters and edible marine fish Indian mackerel (Rastrelliger kanagurta) namely Arsenic (As), Lead (Pb), Cadmium (Cd), Mercury (Hg), Iron (Fe), Manganese (Mn), Copper (Cu), Zinc (Zn) in water and fish tissues (Gills and Liver) of Nelaturu, Krishnapatnam coastal areas. The extent of metal concentrations in the water and levels of heavy metals varied among the various tissues in the fish species studied and the concentrations of the metals found in fish gill, liver tissues were high. At this rate, consumption of marine fish from Nelaturu, Krishnapatnam may lead to heavy toxicity and other related health problems to human and other animals. Control measures are required to reduce aquatic heavy metal pollution in the Nellore coast.

Lipid production from indigenous Greek microalgae: a possible biodiesel source.

Microalgae gained interest for potential use as biodiesel producers, since they synthesize and accumulate significant quantities of lipids. The aim of this work was to isolate indigenous microalgae strains from Greek habitats, study their physicochemical growth conditions and finally select the best ones with respect to overall lipid production and profile. Two sampling sites of marine aquatic ecosystems were selected in Attica prefecture, Greece in order to screen for novel wild type strains with lipid production capacity. Microalgae isolates (59) were obtained from the selected areas and were morphologically and molecularly characterized. Fatty acids were estimated through Flow Cytometry combined with BODIPY staining method. Four isolates were selected for their lipid production properties and were cultivated in 15 L tank cultures. The four isolates were also identified by 18S rDNA gene sequencing. Two of them, Chlorella sp. ΑCΑ9 and ACA17, exhibited both maximum biomass and lipid productivity. Optimization of growth conditions with respect to pH and initial NaNO3 concentration was performed for the two microalgae in 15 L cultures. Finally, 20 L fed batch cultures were set up using the optimum culture conditions. Lipid profiles were stabilized for both strains at dry biomass levels over 1gL-1 and lipid content of 25% (w/w). Two Chlorella strains (ACA9 andACA17) were promising candidates for biodiesel production as they were easily grown in sea water in fed batch systems and produce lipids suitable for biodiesel-especially Chlorella sp. ACA9.

The protection of marine aquatic life: Green Port (EcoPort) model inspired by Green Port concept in selected ports from Turkey, Europe and the USA

Ecological Port, also known as Green Port (EcoPort), is an important development strategy protecting marine aquatic life and ecosystem. It provides business information on environmentally best practices and corporate responsibility centred around marine ports and terminals, including shipping, transport and logistics. Green Port concept gives a great opportunity to make transportation clean and efficient. Marine industry should adopt new legislations to create a clean future. It is the key point to implement strict liquid and solid waste policies and to begin to use low sulphur fuel and electric power whenever possible. Green Ports utilize electric powered cranes and they have strict garbage policies and well-educated personnel. Furthermore, the vessels entering Green Ports must have an accreditated waste management and bunkering plan. In this study, the implementation of the Green Port concept at some selected Turkish, European and the US Ports was given and a simple Green Port Model was prepared.

Dissolved organic matter and its optical characteristics in the Laptev and East Siberian seas: spatial distribution and interannual variability (2003–2011)

Abstract. The East Siberian Arctic Shelf (ESAS) is the broadest and shallowest continental shelf in the world. It is characterized by both the highest rate of coastal erosion in the world and a large riverine input of terrigenous dissolved organic matter (DOM). DOM plays a significant role in marine aquatic ecosystems. The chromophoric fraction of DOM (CDOM) directly affects the quantity and spectral quality of available light, thereby impacting both primary production and ultraviolet (UV) exposure in aquatic ecosystems. A multiyear study of CDOM absorption, fluorescence, and spectral characteristics was carried out over the vast ESAS in the summer–fall seasons. The paper describes observations accomplished at 286 stations and 1766 in situ high-resolution optical measurements distributed along the nearshore zone. Spatial and interannual CDOM dynamics over the ESAS were investigated, and driving factors were identified. It was shown that the atmospheric circulation regime is the dominant factor controlling CDOM distribution on the ESAS. This paper explores the possibility of using CDOM and its spectral parameters to identify the different biogeochemical regimes in the surveyed area. The analysis of CDOM spectral characteristics showed that the major part of the Laptev and East Siberian seas shelf is influenced by terrigenous DOM carried in riverine discharge. Western and eastern provinces of the ESAS with distinctly different DOM optical properties were also identified; a transition between the two provinces at around 165–170° E, also consistent with hydrological and hydrochemical data, is shown. In the western ESAS, a region of substantial river impact, the content of aromatic carbon within DOM remains almost constant. In the eastern ESAS, a gradual decrease in aromaticity percentage was observed, indicating contribution of Pacific-origin waters, where allochthonous DOM with predominantly aliphatic character and much smaller absorption capacity predominates. In addition, we found a stable tendency towards reduced concentrations of CDOM and dissolved lignin and an increase in spectral slope and slope ratio values eastward from the Lena River delta; the Lena is the main supplier of DOM to the eastern Arctic shelf. The strong positive correlation (r = 0.97) between dissolved organic carbon (DOC) and CDOM values in the surface shelf waters influenced by terrigenous discharge indicates that it is feasible to estimate DOC content from CDOM fluorescence assessed in situ using a WETStar fluorometer. This approach is reliable over the salinity range of 3 to 24.5. The fact that there is little difference between predicted and observed parameters indicates that the approach is justified. The direct estimation of DOM optical characteristics in the surface ESAS waters provided by this multiyear study will also be useful for validating and calibrating remote sensing data.

Cu toxicity on growth and chlorophyll-a of Chaetoceros sp.

Phytoplankton is a primary producer in marine aquatic ecosystem. Their sensitivity to metal makes them important to study to predict the environmental impact of pollution. Copper is an essential nutrient for aquatic life as micronutrients on an organism but toxic at high levels. The focus of this study was to assess the toxicity of copper to Chaetoceros sp. on growth and chlorophyll-a content. The result shows that inhibition concentration (IC50) of copper on the microalgae, Chaetoceros sp. was 30.25 μg L-1. Growth of Chaetoceros sp. decreased 16.84% in 16 μg L-1 and 81.97% in 44 μg L-1. Chlorophyll-a content decreased dramatically at 44 μg L-1 compared to control. Increase of the cell size, deformation of cell wall and loss of setae were observed at higher concentration of copper.

Evaluation of the relationship of picoplankton and viruses to environmental variables in a lagoon system (Çakalburnu Lagoon, Turkey)

ABSTRACTLagoons are defined as wetlands separated from the sea coasts on which they are located and sit between continental and marine aquatic ecosystems. Çakalburnu Lagoon is a coastal wetland on the southern side of the Bay of İzmir. Microorganisms, which are quite sensitive to changes occurring in environmental factors, are commonly used to determine the impact of environmental effects on the functioning of the ecosystem. In this study, variations in the abundance and biomass of picoplankton (Synechococcus spp. and bacteria) and the abundance of viruses, which identify the ecological productivity of the food chain, were seasonally examined by epifluorescence microscopy. Moreover, the microbial abundance and biomass relation over time between the physical and chemical parameters was evaluated. According to our results, the maximum abundance of Synechococcus spp. and viruses was 6.7 × 104 cell/ml and 9.9 × 108 cell/ml in the summer, respectively. Otherwise, the highest level of bacteria was measured at 3.6 × 107 cell/ml in the spring. Based on the principal component analysis and Pearson correlation analysis results, we concluded that total suspended solids, Chl-a, particulate organic carbon and particulate organic nitrogen were the major parameters influencing the observed variability of the lagoon system. Overall, to protect and improve the ecological and microbiological quality of aquatic systems such as lagoons, the necessary monitoring and measurement studies should be conducted in these sensitive areas.

Regime shifts, thresholds and multiple stable states in freshwater ecosystems; a critical appraisal of the evidence

The concepts of ecosystem regime shifts, thresholds and alternative or multiple stable states are used extensively in the ecological and environmental management literature. When applied to aquatic ecosystems, these terms are used inconsistently reflecting differing levels of supporting evidence among ecosystem types. Although many aquatic ecosystems around the world have become degraded, the magnitude and causes of changes, relative to the range of historical variability, are poorly known. A working group supported by the Australian Centre for Ecological Analysis and Synthesis (ACEAS) reviewed 135 papers on freshwater ecosystems to assess the evidence for pressure-induced non-linear changes in freshwater ecosystems; these papers used terms indicating sudden and non-linear change in their titles and key words, and so was a positively biased sample. We scrutinized papers for study context and methods, ecosystem characteristics and focus, types of pressures and ecological responses considered, and the type of change reported (i.e., gradual, non-linear, hysteretic or irreversible change). There was little empirical evidence for regime shifts and changes between multiple or alternative stable states in these studies although some shifts between turbid phytoplankton-dominated states and clear-water, macrophyte-dominated states were reported in shallow lakes in temperate climates. We found limited understanding of the subtleties of the relevant theoretical concepts and encountered few mechanistic studies that investigated or identified cause-and-effect relationships between ecological responses and nominal pressures. Our results mirror those of reviews for estuarine, nearshore and marine aquatic ecosystems, demonstrating that although the concepts of regime shifts and alternative stable states have become prominent in the scientific and management literature, their empirical underpinning is weak outside of a specific environmental setting. The application of these concepts in future research and management applications should include evidence on the mechanistic links between pressures and consequent ecological change. Explicit consideration should also be given to whether observed temporal dynamics represent variation along a continuum rather than categorically different states.

Comparative evaluation of impact of Zn and ZnO nanoparticles on brine shrimp (Artemia salina) larvae: effects of particle size and solubility on toxicity.

Brine shrimp (Artemia salina) larvae were exposed to different sizes of zinc (Zn) and zinc oxide (ZnO) nanoparticles (NPs) to evaluate their toxicity in marine aquatic ecosystems. Acute exposure was conducted in seawater with 10, 50 and 100 mg L(-1) concentrations of the NPs for 24 h and 96 h. Phase contrast microscope images confirmed the accumulation of the NPs inside the guts. Artemia were unable to eliminate the ingested particles, which was thought to be due to the formation of massive particles in the guts. Although the suspensions of the NPs did not exhibit any significant acute toxicity within 24 h, mortalities increased remarkably in 96 h and escalated with increasing concentration of NP suspension to 42% for Zn NPs (40-60 nm) (LC50∼ 100 mg L(-1)) and to about 34% for ZnO NPs (10-30 nm) (LC50 > 100 mg L(-1)). The suspensions of Zn NPs were more toxic to Artemia than those of ZnO NPs under comparable regimes. This effect was attributed to higher Zn(2+) levels (ca. up to 8.9 mg L(-1)) released to the medium from Zn NPs in comparison to that measured in the suspensions of ZnO NPs (ca. 5.5 mg L(-1)). In addition, the size of the nanopowders appeared to contribute to the observed toxicities. Although the suspensions possessed aggregates of comparable sizes, smaller Zn NPs (40-60 nm) were relatively more toxic than larger Zn NPs (80-100 nm). Likewise, the suspensions of 10-30 nm ZnO NPs caused higher toxicity than those of 200 nm ZnO NPs. Lipid peroxidation levels were substantially higher in 96 h (p < 0.05), indicating that the toxic effects were due to the oxidative stress.

An integrated environmental approach to investigate biomarker fluctuations in the blue mussel Mytilus edulis L. in the Vilaine estuary, France

Estuarine areas represent complex and highly changing environments at the interface between freshwater and marine aquatic ecosystems. Therefore, the aquatic organisms living in estuaries have to face highly variable environmental conditions. The aim of this work was to study the influence of environmental changes from either natural or anthropogenic origins on the physiological responses of Mytilus edulis. Mussels were collected in the Vilaine estuary during early summer because this season represents a critical period of active reproduction in mussels and of increased anthropogenic inputs from agricultural and boating activities into the estuary. The physiological status of the mussel M. edulis was evaluated through measurements of a suite of biomarkers related to: oxidative stress (catalase, malondialdehyde), detoxication (benzopyrene hydroxylase, carboxylesterase), neurotoxicity (acetylcholinesterase), reproductive cycle (vitelline, condition index, maturation stages), immunotoxicity (hemocyte concentration, granulocyte percentage, phagocytosis, reactive oxygen species production, oxidative burst), and general physiological stress (lysosomal stability). A selection of relevant organic contaminant (pesticides, (polycyclic aromatic hydrocarbons, polychlorobiphenyls) was measured as well as environmental parameters (water temperature, salinity, total suspended solids, turbidity, chlorophyll a, pheopigments) and mussel phycotoxin contamination. Two locations differently exposed to the plume of the Vilaine River were compared. Both temporal and inter-site variations of these biomarkers were studied. Our results show that reproduction cycle and environmental parameters such as temperature, organic ontaminants, and algal blooms could strongly influence the biomarker responses. These observations highlight the necessity to conduct integrated environmental approaches in order to better understand the causes of biomarker variations.

Coastal lagoons: “transitional ecosystems” between transitional and coastal waters

The European Water Framework Directive (WFD) establishes a well differentiated typology of water bodies on the basis of scientific and biological criteria. For coastal waters, such criteria have long been established, while for transitional waters they are still under discussion. One of the difficulties when applying the WFD to coastal lagoons is to include them in only one of these categories, and while there is no doubt about the nature of estuaries as transitional waters, there is some controversy concerning lagoons. To what extent, reference conditions may be similar for estuaries and lagoons, or whether features common to all coastal lagoons are more important for differentiating them from other water bodies than the fact that there is (or is not) any fresh water influence, is something that remains unclear and is discussed in this work. Coastal lagoons and estuaries form part of a continuum between continental and marine aquatic ecosystems. Shelter, strong boundaries or gradients with adjacent ecosystems, anomalies in salinity regarding freshwater or marine ecosystems, shallowness, etc. all contribute to the high biological productivity of estuaries and lagoons and determine common ecological guilds in the species inhabiting them. On the other hand, fresh water influence, the spatial organization of gradients and environmental variability (longitudinal one-dimensional gradients in estuaries versus complex patterns and three-dimensional heterogeneity in lagoons) constitute the main differences, since these factors affect both the species composition and the dominance of certain ecological guilds and, probably, the system’s complexity and homeostatic capability. In the context of the WFD, coastal lagoons and estuaries are closer to each other than they are to continental or marine waters, and, on the basis of the shared features, they could be intercalibrated and managed together. However, coastal lagoons cannot be considered transitional waters according to the present definition. To assume that fresh water influence is an inherent characteristic to these ecosystems could lead to important changes in the ecological organization and functioning of coastal lagoons where natural fresh water input is low or null. In our opinion, the present day definition of transitional waters should be changed substituting the criterion of fresh water influence by another based on common features, such as relative isolation and anomalies in salinity in water bodies with marine influence. Otherwise, coastal lagoons should be considered a particularly characteristic type of water mass for establishing reference conditions of ecological status.

Fluorescence measured using the WETStar DOM fluorometer as a proxy for dissolved matter absorption

Dissolved organic matter (DOM) plays a significant role in freshwater and marine aquatic ecosystems including its effects on nutrients and carbon cycling and trace metal and contaminant availability. The colored fraction of DOM, CDOM, directly affects the quantity and spectral quality of available light, thereby impacting both primary production and UV exposure in aquatic ecosystems. Measuring the DOM absorption coefficient in situ is difficult because it requires prefiltration of the sample. From measurements made in inland, riverine, estuarine and coastal environments, we show that using the WETStar fluorometer (WET Labs), good estimates of dissolved absorption can be obtained from DOM fluorescence (DOM-FL) measured in situ on unfiltered samples. DOM-FL measured with the in situ fluorometer compare very well to values obtained on filtered samples using more sophisticated laboratory spectrofluorometers. Acquisition of high frequency, long-term data series or high-resolution profiles is feasible and artifacts resulting from filtration or sample storage can be avoided when measurements are made using the WETStar DOM fluorometer. The utility of high-resolution DOM-FL profiles for biogeochemical studies is illustrated by in situ data obtained in the East Siberian Sea.

Accumulation, Distribution and Metabolism of 14C- 1,1,1- Trichloro-2, 2-, Bis- (P-Chlorophenyl) Ethane (p,p′-DDT) Residues in a Model Tropical Marine Ecosystem

Accumulation, distribution and metabolism of ring labelled, 14C-1,1,1, - trichloro-2,2-bis(p-chlorophenyl)ethane (p,p′-DDT) in a model marine aquatic ecosystem consisting of sea water, sediment, oysters (Isognomonon alatus) and Humbug fish (Dascillus aruanus) were studied in the laboratory. 14C-p,p′-DDT distributes rapidly in the ecosystem immediately after application on the water surface with reduction of its concentration in the water phase from 1.18 ng g−1 to 0.71 ng g−1 after 2 hours and an increase in its content in the sediment and oysters. The bioconcentration factor reached a maximum of 19× 103 in oysters, and 1657 in Humbug fish after 24 hours. The sediment concentration reached 117 ng g−1 after 168 hours from start of application. A peak bioconcentration factor of 111 × 103 was calculated after 120 hours when 0.24 mg kg−1 of 14C-p,p′-DDT was maintained through dosing every 24 hours with 0.002 mg kg−1 of a mixture of labelled and non-labelled pesticide. The rate of depuration of accumulated 14C-p,p′-DDT sediment residues was up to 78.3% after 24 hours while oysters lost only 14.0% during the same period. The loss in Humbug fish was only 22.2% in three days. Volatilisation and sorption losses from seawater alone (without sediment/biota) were found to be very high in the range of 73.8 – 91.5% over 24 h for p,p′-DDT in aerated and non-aerated ecosystem. Gas chromatograph and TLC analysis of water, sediment and oyster samples revealed presence of p,p′-DDT and substantial amounts of p,p′-DDE and p,p′-DDD three days after pesticide dosage.

Susceptibility of larval and juvenile instars of the sand crab, Portunus pelagicus (L.), to sea water contaminated by chromium, nickel or copper

The acute toxicities of Cu2+, Ni2+ and Cr(V1) in sea water to larval life stages of the sand crab, Portunus pelagicus, were determined in a laboratory study and compared with published data for the toxicity of heavy metal cations to this species. This showed the relative acute toxicities to be in the order Cu2+ &gt; Cd2+ ≥ Zn2+ &gt; Ni2+&gt; Cr(V1). Sublethal effects attributable to exposure to sea water contaminated by some of these cations were investigated for both larval and juvenile crab life stages. The effects quantified were inhibition of larval moulting, increase in the duration of development period, and reduced size achieved by successive juvenile crab instars. In each case, the chronic levels of cation contamination in seawater associated with these effects exceeded the Australian guidelines for the protection of marine aquatic ecosystems, but in some cases the safety margin was less than an order of magnitude. In addition, bioconcentration relationships for Cr were determined on a whole-animal and an exoskeleton basis.