Cultural eutrophication of shallow coastal waters: Coupling changing anthropogenic nutrient inputs to regional management approaches

Coastal waters comprise only about 15% of the world's ocean area, yet account for nearly half of its primary and secondary production (Wollast 1991). This disparity can in part be traced to anthropogenic nutrient, specifically nitrogen (N), loading. Regionally, N-sensitive coastal waters are experiencing unprecedented nutrient-driven eutophication, deteriorating water quality (i.e. hypoxia, anoxia, toxicity), habitat loss and declines in desirable fish stocks and yields. In most coastal regions externally-supplied “new” nutrient inputs are growing, diversifying and changing as a result of urbanization, industrial and agricultural development. In some cases (e.g. Eastern Europe), declining economic condition shave led to a reversal of this scenario. A need exists to identify key nutrient sources (and changes therein) supporting eutrophication and its socio-economic consequences. While we are addressing and managing terrestrial (i.e. point and non-point source runoff) “new” nutrient inputs, key “out of sight out of mind” anthropogenic nutrient sources and their effects on eutrophication remain poorly understood and managed. These include atmospheric deposition and groundwater, which can account for as much as half the “new” N entering North American (U.S. Atlantic East Coast) and European (Baltic Sea) coastal waters. Here, I will examine these emerging nutrient sources and their roles in shallow coastal biogeochemical and trophodynamics alterations. Technological and conceptual tools and approaches aimed at improving our functional understanding of these and other “new” nutrient-eutrophication interactions are discussed.     

‘Oyster watch’: Monitoring trace metal and organochlorine concentrations in Sydney''s coastal waters

This paper examines concentrations of trace contaminants in oysters placed in inshore and offshore waters before and after the change to offshore disposal of sewage near Sydney, NSW, Australia. The ability to compare inshore and offshore concentrations before and after the event allows the formulation of unconfounded conclusions about the impact of sewage on the availablity of trace contaminants in the coastal environment and the effect of the change in the method of disposal of Sydney's sewage on the availability of those contaminants.

The data show clearly that the diversion of sewage from nearshore to offshore areas has resulted in a significant drop in the concentrations of organochlorines in oysters deployed near sewage outfalls in the nearshore region. In offshore areas, there were no differences detected among regions prior to the commissioning of deepwater outfalls. In the post commissioning period there were a number of instances when trace metal concentrations in the regions were different from each other, but these differences were not correlated with proximity to the sewage outfalls nor was a particular metal consistently elevated, so it was concluded that the causes of difference were not related to the presence of the sewage outfalls.

This study has demonstrated that oysters were useful indicators of trace metal and organochlorine contamination of marine waters; that relatively high levels of contamination of inshore waters near sewage outfalls prior to deepwater sewage disposal were reduced, to be not different from other parts of Sydney's coastline after the commencement of deepwater discharge, and that there was no concommitant increase in accumulation of contaminants in offshore waters. Further, preliminary indications are that Sydney's coastal waters are not very heavily contaminated by trace contaminants in comparison to areas of NSW with much lower levels of development. Concentrations of organochlorines are, however, high in comparison to data from similarly developed areas of the USA.     

Sensitivity of the half-life time of water exchange in coastal waters

A three-dimensional model was established to investigate water exchange in coastal waters, and applied to Qinzhou Bay(QZB) in the South China Sea. Given the strong tidal current in QZB, a half-life time was calculated for water exchange by filtering the tidal signal from the concentrations of a conservative substance. In a control run driven by the tide, without external inputs and an open boundary concentration of zero, it was estimated that the average half-life time in QZB was 54.8 d. Numerical experiments showed that wind accounted for an 11.9% reduction in the half-life time to 48.3 d. When rivers were included in the model, the half-life time decreased by 74.6% to 13.9 d. Sensitivity experiments showed that the half-life time for water exchange was greatly affected by the concentration of the conservative substance which was used at the open boundary. In response to 10,20, 30, and 40% increases in the boundary concentration, the half-life time increased to 91.5, 168.3, 186.2, and 229.1 d,respectively. Results also suggested that for coastal bays with large intertidal areas such as QZB, consideration of the wet and dry processes produced more accurate simulations of the hydrodynamics and the half-life times. Simulations, which did not incorporate wet and dry processes, were more than likely to have overestimated or underestimated the half-life times for water exchange.     

The initial assessment of trace metal pollution in coastal sediments

Coastal sediments are important hosts for pollutant trace metals, but analytical difficulties can prevent them being included in routine environmental monitoring programmes. In order to identify a suitable approach to the problem, an established simple technique has been evaluated for the initial assessment of trace metal pollution in coastal sediments. The technique, which involves leaching the samples with cold 0.5 N HCl, has been applied to surface sediments from two Greek gulfs and has been shown to provide a rapid, inexpensive way of initially establishing the gross degree to which a sediment population has been subjected to trace metal pollution from the overlying waters.     

The sandhopper Talitrus saltator (Crustacea: Amphipoda) as a biomonitor of trace metal bioavailabilities in European coastal waters

The amphipod crustacean Talitrus saltator is an established, easily accessible, biomonitor of trace metal bioavailabilities in coastal waters. We have carried out a geographically widespread collection of T. saltator from European shores, stretching from the north-west Atlantic through the Baltic to the Mediterranean. A primary aim of the work was to establish a database of accumulated trace metal concentrations (Cd, Cr, Cu, Fe, Mn and Zn) in this biomonitor. Statistical analysis has shown significant geographical differences in the bioavailabilities of all the metals, the most distinct being copper, iron and manganese. It has proved possible to identify unusually high accumulated concentrations of Cd, Cr, Cu, Fe, Mn and Zn in this biomonitor, indicative of high metal bioavailability at a particular site. These may serve as reference points for future biomonitoring programmes seeking to identify metal contamination in coastal waters.     

Utilization of a submersible UV fluorometer for monitoring anthropogenic inputs in the Mediterranean coastal waters

We evaluated the performances of a submersible ultraviolet fluorometer (EnviroFlu-HC, TriOS Optical Sensors) dedicated to the real time measurement of polycyclic aromatic hydrocarbons (PAHs) in the aquatic media. We conducted calibration experiments and in situ measurements in the coastal Mediterranean Sea. We found that the EnviroFlu-HC was not strictly specific to PAHs, even though it exhibited the highest sensitivity for phenanthrene, but could response to tryptophan-like material as well, and in a much less extent, to humic substances. The sensor signal showed great spatial and temporal variations in clean and polluted sites, with likely a high contribution of PAHs in the harbors, and a high contribution of tryptophan-like and humic-like materials in the sewage effluent. We conclude that the EnviroFlu-HC is a good tool for monitoring anthropogenic inputs in the coastal waters, although its utilization should be combined to other fluorescence measurements to improve the information about the nature of the aromatic compounds detected.     

Trace metal levels in coastal sea water investigation of Danish waters

The concentration levels of Cd (25 ng l^?1), Cu (0.45 μg l^?1), Ni (0.48 μg l^?1), Fe (0.2–7.0 μg l^?1), Pb (40 ng l^?1) and Zn (0.80 μg l^?1) have been determined in the Danish Sounds and in the Kattegat. Different sampling techniques have been used and analyses have been carried out separately by two different investigators, both using freon-extraction followed by determination by atomic absorption spectrometry (a.a.s.). Except for iron, found mainly in the particulate phase, the metals are found predominantly in a dissolved and labile (extractable) form. The results are compared with trace metal levels found in the two main water masses entering the Kattegat—the North Sea and the Baltic Sea.     

Sensitivity of bacterioplankton nitrogen metabolism to eutrophication in sub-tropical coastal waters of Key West, Florida

Expression of intracellular ammonium assimilation enzymes were used to assess the response of nitrogen (N) metabolism in bacterioplankton to N-loading of sub-tropical coastal waters of Key West, Florida. Specific activities of glutamine synthetase (GS) and total glutamate dehydrogenase (GDH_T) were measured on the bacterial size fraction (<0.8 μm) to assess N-deplete versus N-replete metabolic states, respectively. Enzyme results were compared to concentrations of dissolved organic matter and nutrients and to the biomass and production of phytoplankton and bacteria. Concentrations of dissolved inorganic N (DIN), dissolved organic N (DON), and dissolved organic carbon (DOC) positively correlated with specific activities of GDH_T and negatively correlated with that of GS. Total dissolved N (TDN) concentration explained 81% of variance in bacterioplankton GDH_T:GS activity ratio. The GDH_T:GS ratio, TDN, DOC, and bacterial parameters decreased in magnitude along a tidally dynamic trophic gradient from north of Key West to south at the reef tract, which is consistent with the combined effects of localized coastal eutrophication and tidal exchange of seawater from the Southwest Florida Shelf and Florida Strait. The N-replete bacterioplankton north of Key West can regenerate ammonium which sustains primary production transported south to the reef. The range in GDH_T:GS ratios was 5–30 times greater than that for commonly used indicators of planktonic eutrophication, which emphasizes the sensitivity of bacterioplankton N-metabolism to changes in N-bioavailability caused by nutrient pollution in sub-tropical coastal waters and utility of GDH_T:GS ratio as an bioindicator of N-replete conditions.     

Dispersion of dissolved trace metals from the Irish Sea into Scottish coastal waters

An investigation has been undertaken into the dispersal of contaminants from the Irish Sea into coastal waters of Scotland via the North Channel. A total of 97 surface samples have been analysed for dissolved copper, cadmium and lead. Salinity and reactive phosphate have also been determined. Evidence is presented to suggest that copper, cadmium and reactive phosphate behave essentially conservatively on mixing into Scottish coastal waters. This behaviour is likened to the dispersal of¹³⁷Cs from the Sellafield nuclear fuel reprocessing plant. It is suggested that this simple mechanism is inadequate to account for the lead distribution. It is proposed that this element is partly taken up by suspended particulates and sediments in the well-mixed turbid waters of the North Channel.It has been demonstrated elsewhere that contaminants from the Irish Sea, such as¹³⁷Cs enter the Firth of Clyde from the North Channel. In the present study North Channel waters are demonstrated to be an important source of trace metals to the Firth of Clyde. At the time of this survey however high concentrations of trace metals were not entering the Firth of Clyde from the North Channel. This is principally attributed to a salinity front associated with the entrance of the Firth which hinders transport across the sill.     

Synoptic survey on dissolved trace metal levels in Baltic surface waters

A total of 95 surface water samples (6 m depth) was collected during a transect from the Bothnian Bay to Kiel between 28 August and 5 September 1982. This report presents the dissolved trace metal (<0.4 μm) and the associated hydrographic and nutrient data. Except for aluminium, all other metals determined (Zn, Cd, Cu, Ni, Fe, Mn) showed a rather homogeneous distribution within the subregions, with highest values in the Bothnian Bay (except for Mn) and net variations of the individual samples of about 20%. Cadmium, copper and nickel reveal conservative behaviour when values from this study and literature data from the Kattegat and North Sea area are plotted against salinity.     

Survey of tar,hydrocarbon and metal pollution in the coastal waters of Oman

Quantitative beach sampling conducted after the S. W. monsoon season yielded average standing stocks of tar ranging from 5 to 2325 g m^?1 of shoreline with overall average of 224 g m^?1. Values are among the highest reported for any world area and show a trend of increasing levels of oil residues close to the Strait of Hormuz. Data support the premise that tanker deballasting is a major source of oil pollution on the Omani coast. Locally high levels were seen near offshore tanker loading facilities. Petroleum hydrocarbons in rock oysters increased in a south to north gradient consistent with beach tar observations. But relatively low hydrocarbon levels in biota coupled with observations of very little floating tar suggests that oil released in Omani coastal waters aggregates, sinks, and reaches the coast as heavy tar lumps. Except for elevated levels of Cd at two stations, heavy metal and chlorinated hydrocarbon concentrations were low compared to more industrialized world areas. Suggestions are made to improve the effectiveness of future pollution studies in the Gulf Region.     

The use of kelp sieve tube sap metal composition to characterize urban runoff in southern California coastal waters

This study introduces an innovative method for biomonitoring using giant kelp (Macrocystis pyrifera) sieve tube sap (STS) metal concentrations as an indication of pollution influence. STS was sampled from fronds collected from 10 southern California locations, including two reference sites on Santa Catalina Island. Using ICP-MS methodology, STS concentrations of 17 different metals were measured (n = 495). Several metals associated with pollution showed the highest STS concentrations and most seasonal variation from populations inside the Port of Los Angeles/Long Beach. Lowest concentrations were measured at less-urbanized areas: Santa Catalina Island and Malibu. Some metals showed a spatial gradient in STS metal concentration with increasing distance from point sources (i.e. Los Angeles River). Cluster analyses indicate that polluted seawater may affect kelp uptake of metals essential for cellular function. Results show that this method can be useful in describing bioavailable metal pollution with implications for accumulation within an important ecosystem.     

Munitions in British coastal waters

Munitions are now widely distributed throughout the coastal waters of the British Isles following accidental losses or deliberate dumping in the past. Substantial quantities have been discovered by the general public, and occasional injuries or fatalities have resulted from the improper handling of a small proportion found in dangerous condition.     

Quantities of some dangerous substances discharged to British coastal waters

Estimation of the quantities of cadmium, mercury, lindane, DDT, ‘drins’ (aldrin, dieldrin and endrin), PCBs, copper, lead, chromium, nickel, zinc and arsenic discharged to the tidal waters of the UK is described and the results are presented for the major geographic regions of the UK. Consideration is also given to the significance of different sources of discharge of these substances in terms of their contribution to the overall loads reaching the sea. For most of these substances, rivers contribute the major proportion of the quantities discharged.     

Biomonitoring of heavy metals and trace organics using the intertidal mussel Perna viridis in Hong Kong coastal waters

This paper presents the results of a 6-year (1998–2003) survey of trace toxics in the intertidal mussel Perna viridis conducted by the Hong Kong Environmental Protection Department. Concentrations of heavy metals and trace organics were measured in the soft bodies of P. viridis collected from five sites in Hong Kong waters, i.e. Wu Kai Sha (Tolo Harbour), Ma Wan (Northwest), Tsim Sha Tsui (Victoria Harbour), Tai Tam (Hong Kong South) and Lamma Island (Southern Waters) in order to establish the spatial patterns of contaminants in mussels. Among the metals analysed, Cd showed a significant concentration gradient in Hong Kong waters. The levels of Cd in P. viridis were significantly higher at Ma Wan as compared to the other sites studied. Ma Wan also had relatively higher concentrations of Pb. Mn concentrations were particularly prominent at Wu Kai Sha. Significantly higher concentrations of Hg and Cu were recorded at Tai Tam and Tsim Sha Tsui. Tai Tam and Wu Kai Sha had higher levels of V; whereas higher Ni concentrations were recorded at Lamma Island and Tai Tam. No clear spatial patterns for Al, As, Cr, Fe and Zn were observed.

Higher concentrations of PAHs in P. viridis were observed around urban centres impacted by sewage discharges (e.g. Tsim Sha Tsui); whereas higher PCB levels were found not only in Tsim Sha Tsui but also in less urbanised areas such as Lamma Island and Tai Tam, suggesting that these may be due to non-sewage related inputs. The study also shows that Northwest and Southern waters are subject to a higher degree of DDT pollution compared with other sites. Of the 17 dioxin compounds analysed, positive data were mostly recorded for two compounds which are of low toxicity (i.e. OCDD and 1,2,3,4,6,7,8-HpCDD) whereas the most toxic congeners (i.e. 2,3,7,8-TCDD and 1,2,3,7,8-PeCDD) were not detected in the 6 years of monitoring. In general, the levels of OCDD in P. viridis were found to be higher in Tai Tam and Lamma Island in Southern Waters of Hong Kong.

This study found that the levels of some highly toxic heavy metals (i.e. Cd, Hg and Pb) in the mussel P. viridis did not exceed the recommended limits for shellfish as food in Hong Kong (i.e. Cd: 2.0 ppm; Hg: 0.5 ppm; Pb: 6.0 ppm wet weight). The levels of As and Ni in P. viridis were also well below the action limits set by the US FDA (i.e. As: 86 ppm; Ni: 80 ppm wet weight). DDT and PCB contaminations in P. viridis were below the concentrations of concern. Compared with data obtained in the 1980s, the current levels of DDTs in P. viridis were 4–16 times lower; whereas Pb concentrations recorded in Tsim Sha Tsui have also been lowered significantly. This is mainly related to reduction in local and regional pollution sources in the past 20 years.     

Sub-kilometer length scales in coastal waters

Patchiness or spatial variability is ubiquitous in marine systems. With increasing anthropogenic impacts to coastal resources and coastal systems being disproportionately large contributors to ocean productivity, identifying the spatial scales of this patchiness, particularly in coastal waters, is of critical importance to understand coastal ecosystem dynamics. The current work focuses on fine scale structure in three coastal regions. More specifically, we utilize variogram analyses to identify sub-kilometer scales of variability in biological and physical parameters measured by an autonomous underwater vehicle (AUV) in the Mid-Atlantic Bight, Monterey Bay, and in San Luis Obispo Bay between 2001 and 2004. Critical scales of variability in density, turbidity, fluorescence, and bioluminescence are examined as a function of depth and distance offshore. Furthermore, the effects of undersampling are assessed using predictive error analysis. Results indicate the presence of scales of variability ranging from 10s to 100s of meters and provide valuable insight for sampling design and resource allocation for future studies.     

Present state and historical changes of trace metal pollution in Kaoping coastal sediments, southwestern Taiwan

Surface and gravity-cored sediments were collected from the Kaoping coastal area off southwestern Taiwan to determine particle size, organic carbon, trace metal concentration and enrichment factor (EF), 210Pb dating, and 206Pb/207Pb ratio for determining present and historical metal pollution. Surface distributions of trace metals ranged from 0.02 to 0.13 mg/kg for Cd (EF: 0.16-1.65), from 35 to 189 mg/kg for Cr (EF: 0.85-2.92), from 25 to 64 mg/kg for Ni (EF: 0.53-2.38), from 10 to 32 mg/kg for Pb (EF: 1.20-4.94), and from 29 to 129 mg/kg for Zn (EF: 1.18-3.50). Trace metal concentrations correlate closely with distributions of mud (<63 microm) and organic carbon which accumulate largely around river mouths and within the Kaoping Canyon. With the exception of Cd, Cr and Ni in certain areas with rather coarse sediments, metals were generally elevated above the baseline levels over the studied area. Metals were also relatively enriched in areas with high contents of mud and organic carbon. Sedimentation rates derived from the excess 210Pb data in core sediments sampled from the canyon illustrate metal pollution beginning around 1970 that is corresponding to the booming time of economic growth in Taiwan. Meanwhile, the status of Pb pollution in core sediments is verified by an inversed correlation between 206Pb/207Pb ratios and Pb concentrations. Anthropogenic Pb and other metals in the studied area were apparently derived primarily from the Kaoping River and accumulated around the river mouth and within the Kaoping Canyon. The Kaoping Canyon appears to act as a major sink for river borne trace metals.