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The present work investigates the inorganic nitrogenous nutrition of the phytoplanktonic community and its association with the bacterial role in the remineralisation and/or utilisation of inorganic nitrogen, in the waters of the Menai Strait. The field study lead to the recognition of four distinct phases in the seasonal cycle, based on measurements of primary plankton production and metabolism of nitrate and ammonium by the algae and bacteria. These were first the net autotrophic phase (April and May), followed by the net heterotrophic phase (June), then the secondary net autotrophic phase (July and August) and finally, the regenerative phase (remainder of the year). The phytoplankton seasonal pattern was characterised by nitrate-based production in the spring followed by ammonium-based production in summer and autumn, associated with the ambient availability of these nutrients. Bacteria accounted for up to 70% of the total inorganic nitrogen taken up with nitrate contributing heavily to bacterial production (up to 80%) early in the year. Whilst the maximum contribution of the heterotrophs to the total uptake was observed during the net heterotrophic phase, the lowest (<25%) was during the net autotrophic periods of the seasonal cycle. Calculations suggest that a maximum of 67% of algal ammonium uptake came from bacterial recycling. Only in June was there evidence of competition between algae and bacteria for nitrogen which is believed to have contributed to the sharp decline of the phytoplankton, at this time of the year. There was no evidence for nutrient limitation of the algae at other times of the season. There was also evidence for uptake of nitrate and ammonium in conditions of total darkness by both the bacteria and the algae, with bacteria accounting for a maximum of-75% the total nitrate and ammonium uptake. Ammonium was preferred over nitrate by the autotrophs and the heterotrophs. However, early in the year, when both primary and bacterial production were nitrate based, nitrate was utilised equitably with its environmental availability. For increasing concentrations of ammonium, bacteria clearly rejected the more oxidised form of inorganic nitrogen. The seasonal variation of 13C (as NaH13CO3) uptake by the populations studied was also investigated and there was strong evidence for heterotrophic uptake. Over the diel cycle, the contribution of bacteria to the total 13 C uptake amounted to a maximum of 44% during the net heterotrophic phase. In dark conditions, this percentage increased to a value of 60%, measured on the same occasion. The ambient availability of inorganic nitrogen seemed to influence the proportion of carbon fixed by the autotrophs that was inferred to be transferred to the bacteria. The assumed carbon transference from the autotrophs to the heterotrophs was highest in the spring, following a period of sufficiency of inorganic nitrogen, and lowest during summer (despite peaks of primary production), associated with conditions of ambient nitrogen depletion. It is widely hypothesised that bacteria take up inorganic nitrogen in order to be able to utilise carbon-rich, nitrogen-deficient compounds and so maintain a constant C:N cell quota. From a series of laboratory experiments, it was observed that the C:N ratio of the dissolved organic matter (DOM) used by the bacteria set the boundary on the role of these organisms as inorganic N net consumers or remineralisers. The laboratory work was interpreted as showing that when DOM was the major nitrogen source for growth, bacteria excreted the excess nitrogen as ammonium whereas at high C:N ratios, bacteria took up and conserved nitrogen. In the latter circumstances, when nitrogen was limiting, bacteria appeared to increase respiratory losses in order to dispose of the excess carbon. By contrast at low C:N ratios, carbon conservation occurred. It was concluded that if the release of DOM by the algae is the prime source of organic material for the bacteria, then this switching of the inorganic nitrogen metabolism of the bacteria, will be ultimately driven by the algae. These results were used to interpret the seasonal dynamics of the phytoplanlctonic and bacterial inorganic nitrogen metabolism in the Menai Strait.

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The interaction of microorganisms with sediments can enhance their survival by reducing exposure to various stressors and thus marine sediments may act as reservoirs for pathogenic microorganisms. In coastal waters there can be an increased risk of infection to humans due to the possible re-suspension of these microorganisms during recreational activities. This research attempts to more accurately identify environmental exposure in the first stage of a health risk assessment in recreational coastal waters. Techniques were developed to successfully separate microorganisms from sediment particles. Of the methods investigated, subjecting diluted sediment samples to a sonication bath for 10 minutes was found to be the most efficient separation technique over a range of sediment types. This method was therefore used in the subsequent studies to enumerate organisms from the surface sediment layer, as distinct from the water column. Faecal coliforms were enumerated by membrane filtration in both water and sediment from three Adelaide metropolitan recreational coastal sites, chosen to represent different physical sediment characteristics, over a 12-month period. All sites investigated met current National Health and Medical Research Council Guidelines for primary contact recreation. Faecal coliform concentrations were generally greater in sediment compared with overlying water for all samples. This was most evident in sediment consisting of greater silt/clay and organic carbon content (with up to 1000 times higher concentrations in the surface sediment layer compared with overlying water). For coastal recreational sites impacted by stormwater or river discharges, high faecal coliform concentrations were found to be associated with rainfall. A laboratory-based microcosm study utilising intact sediment cores was undertaken to determine the decay rates of faecal indicator organisms (E. coli, enterococci and somatic coliphage) and pathogens (Salmonella derby and S. typhimurium) in both overlying water and in various sediment types. For all organisms tested, temperature had an inverse relationship with survival. Greater decay was observed in the overlying water compared to the surface sediment layer. Small particle size and high organic carbon content was found to be more conducive to microbial survival. In general, decay rates of E. coli were significantly greater than enterococci and coliphage. Although no significant correlations were observed between decay rates of the pathogens and indicator organisms, decay of Salmonella spp. in overlying water more closely resembled that of E. coli than that of other indicators. Using decay rates measured in the microcosm study and available dose-response data, a quantitative microbial risk assessment (QMRA) utilising Monte Carlo simulation was undertaken to estimate the risk of infection to Salmonella spp. and rotavirus following exposure to recreational coastal water subject to a range of faecal contamination levels. For modelling purposes, the assumption was made that rotavirus decay was equivalent to coliphage decay. The probability of infection from rotavirus due to exposure to contaminated recreational coastal water was greater than that for Salmonella spp. under all scenarios. This increased probability of infection is linked to the high infectivity of rotavirus compared to Salmonella spp. Results of this research highlight the limited effectiveness of using prescribed faecal coliform concentrations in the water column alone to estimate the risk of exposure to pathogenic microorganisms during recreational activity at coastal areas. It demonstrated that coastal sediments act as a reservoir for both indicator and pathogenic organisms released into the coastal environment. This suggests an increased exposure risk if these organisms are resuspended back into the water column during recreational activity. A combined risk-based monitoring program would provide a more robust and reliable estimate of health risk associated with coastal recreational areas.

Abstract The species composition, distribution and generations of the thaliacea in relation to the sea surface temperature, salinity and chlorophyll a were studied in the Koaping coastal waters, southwestern Taiwan, from June 2001 to October 2002. In all, 16 species of the thaliacea belonging to 3 families and 11 genera were identified. Among these, Doliolum denticulatum was the most dominant species and comprised 62.2% of the numerical total of thaliacea, other common species including: Thalia orientalis (22.8%), Thalia democratica (7.5%), Thalia rhomboids (2.4%) and Dolioliletta gegenbauri (2.3%). The mean numerical abundance of thaliacea was 690.6 1601.4 ind./100m3. Most species showed apparently seasonal changes, with the highest abundance in March 2002 and the lowest was in November 2001. Higher abundances of thaliacea were generally found in the 100m oblique tows when compared with the surface tows, except in March and October 2002 that bulk abundances were found in the surface waters. The variation of thaliacean species composition and abundance among stations and mouths was larger in 2002 than in 2001. Higher similarity in community structure of thaliacea was found between August and November 2001, while larger variations among stations were found in March and July 2002. In general, the abundance of thaliacea species showed significantly negative correlation with water temperature but significantly positive correlations with salinity and chlorophyll a. Blastozooid(phorozooids and gonozooids) of the Doliolum denticulatum and Dolioletta gegenburia dominated in the study area and comprised 99.2% of total doliolids. Blastozooid(gonozooids) was also dominated in Salpida species and comprised 84.3% of total Salpida, except Thalia rhomboids that blastozooid occupied only 40.1%.

Concern about the possible contamination by metals, hydrocarbons and PCBs of Tees Bay and the Tees estuary, and potential sources of such materials has led to this study of surficial sediments. Surface sediment samples were collected from the Tees estuary and Tees Bay and were analysed for grain size, organic carbon content, metals, hydrocarbons (aliphatic and polyaromatic) and polychiorinated biphenyls (PCB5). The Tees estuary sediments are largely organic-rich clayey-silts, while the Bay sediments are organic-poor sands. All of the metals measured (Cd, Co, Cr, Cu, Ni, Pb and Zn) have significantly higher concentrations in the sediments of the Tees estuary than in those of Tees Bay (F<0.01), and the mean averages decrease in the order Zn > Pb> Cr> Cu > Ni > Co> Cd. These significantly higher concentrations remain apparent when the data are normalized to remove the effect of grain size variation, suggesting that the sediments of the Tees estuary are enriched in metals in comparison with the sediments of Tees Bay and that these differences are not the result of the different grain size distributions. Metal partitioning was determined by sequential extraction, using the scheme of Tessier et al. (1979) as recently modified by Ajayi and Van Loon (1989), in order to assess the likely behaviour of metals in the sediments studied. The results of the sequential extraction showed that the partitioning patterns of Cd, Cr, Cu and Zn differed between the marine and estuarine sediments. In the Tees Bay sediments the residual fraction hosted >50% of all of the metals, except Cd and Pb. In the Tees estuary, however, this fraction only accounted for >50% of the Cd, Co and Ni. Significant portions of Cd are contained in fractions 1 and 2 in both the Tees estuary sediments and those from Tees Bay. Because of the toxicity and availability of Cd this may pose a serious problem to the ecosystem. The total Pb in the sediments is also quite high, particularly in the Tees estuary, and even the small proportion in fraction 2 could cause deleterious effects. High concentrations of Cd and Pd, in Tees Bay and the Tees estuary sediments, and Cr and Zn, in Tees estuary sediments, were associated with fraction 3. Concern is directed to heavy metals associated with fraction 3 because changing environmental conditions can transfer these elements from the sediments into the aqueous phase. Cu was the only metal significantly associated with fraction 4. This fraction is likely to have an important role as a sink for trace metals, particularly for Cu and to a lesser extent Cr and Zn. Petroleum hydrocarbons, both aliphatic and polyaromatic (PAHs), were detected and quantified in all samples. The distributions of the n-alkanes, acyclic isoprenoids (especially pristane from coal), triterpanes and steranes, in most sediments from both areas, were indicative of pollution by fossil fuels. On the other hand, a few sediments from the estuary contain hydrocarbons from both biogenic and anthropogenic sources. Polyaromatic hydrocarbon assemblages observed in the samples were relatively rich in hydrocarbons having petrogenic origins. However, the presence of pyrolytic derived components was also indicated by several characteristic component composition ratios. Single PCB congeners were determined in the sediments studied. The PCB profile is fairly constant in sediments from both areas and similar to that of Aroclor 1260 and 1254. The similarity to the commercial mixtures, with only a slight enrichment of the lighter congeners, indicates that sources responsible for PCB pollution are located in the Tees area. The sediments of the Tees estuary tend to be more highly polluted, by metals, hydrocarbons and PCBs, than those of the Bay, particularly in the middle section of the estuary. However, there is a general decrease in the concentrations of these compounds from the middle to the mouth of the estuary, while within the Bay area offshore sites showed higher concentrations. Distributions of inorganic and organic constituents in the Tees Bay were significantly influenced by the organic carbon content and particle size of sediments.

Abstract The species composition, abundance, body lengths and stages of chaetognaths in relation to environmental factors at nine stations in Kaoping coastal waters were investigated during June 2001 to March 2002. In the surface tows, 20 species of chaetognaths, belonging to 10 families and 4 orders, were found, with the mean abundance of 17753 ¡Ó14593 ind./ 100m3. The 4 most dominant species, Flaccisagitta enflata, Aidanosagitta crassa, Sagitta bipuncata and Ferosagitta ferox, comprised > 80% of total chaetognaths. Flaccisagitta enflata was the most common and abundant species and occupied 53% of total chaetognaths. In 100m oblique tows, 21 species of chaetognaths, belonging to 11 families and 4 orders were found, with the mean abundance of 23535 ¡Ó 18696 ind./ 100m3. The 4 most dominant species were Flaccisagitta enflata, Aidanosagitta regularis, Serratosagitta pacifica and Aidanosagitta crassa, and comprised 77% of total chaetognths. Pseudosagitta lyra was the species found only in the 100m oblique tows. The abundance of chaetognaths changed with seasons and had the highest abundance in summer and the lowest in late autumn. The relation between abundance of chaetognaths showed significantly negative relationship with salinity but not for temperature, and had larger variation when salinity > 32 o/oo. Multi-Dimensional Scaling (MDS) method was used to elucidate the variation of chaetognaths community among seasons and stations. The community structure of chaetognaths had somewhat difference among seasons, with higher similarity between August and November, but these two months showed apparently different from June and March. The variation of chaetognaths community among stations was different seasonally, with higher in August and lower in March and June. Furthermore, three species groups were distinguished and their distribution patterns were herein disscussed. The Stage¢¹of chaetognaths dominated in this study area and occupied > 70 % of total count, and the number decreased rapidly following the developmental stages. The most dominant species, Flaccisagitta enflata, was also dominated by stage¢¹throughout the year, implied it might breed in the whole year. The body length of chaetognaths increased apparently with increasing of developmental stages, but overlapped among stages due to the wider variation in each stage.

Yes / Coral reefs are important ecosystems that not only provide shelter and breeding ground for many marine species, but can also control of carbon dioxide level in ocean and act as coastal protection mechanism. Reduction of coral reefs at Singapore coastal waters (SCW) region remains as an important study to identify the environmental impact from its busy industrial activities especially at the surrounding of Jurong Island in the south. This kind of study at SCW was often being related to issues such as turbidity, sedimentation, pollutant transport (from industry activities) effects in literatures, but seldom investigated from the thermal change aspect. In this paper, a computational model was constructed using the Delft3D hydrodynamic module to produce wave simulations on sea regions surrounding Singapore Island. The complicated semi-diurnal and diurnal tidal wave events experienced by SCW were simulated for 2 weeks duration and compared to the Admiralty measured data. To simulate the thermal mapping at the south Singapore coastal waters (SSCW) region, we first adapted a conversion of industrial to thermal discharge; then from the discharge affected area a thermal map was further computed to compare with the measured coral map. The outcomes show that the proposed novel thermal modelling approach has quite precisely simulated the coral map at SSCW, with the condition that the near-field thermal sources are considered (with the coverage area in the limit of 20 km × 20 km). / The author also acknowledges the support of Nazarbayev University’s (Kazakhstan) research seed grant no. KF-12/6 for purchasing and providing the Delft3D software used in this study (which the author is the principal investigator of the grant)