The Netherlands' environmental policy for the North Sea and Wadden Sea

The water quality management of The Netherlands' part of the North Sea (57 000 km² continental shelf of which 7600 km² is territorial sea to 12 miles) and the Wadden Sea (a wetland area behind the northern coastal islands), is described on the basis of recent scientific studies and governmental policy documents. The links with international conventions and treaties are mentioned. The overall water quality in these areas has significantly deteriorated over the last century, notably since the post-war industrial revival, due to a great number of emissions of heavy metals and organochlorine substances. A dramatic decline of seals and porpoises has occurred. However, over the last few years some emissions have been reduced. A national ecological research programme for the North Sea is developing. Monitoring is concentrated on levels of pollutants as well as on effects upon biota. Baseline standards are now being developed as references for further action against pollution. If the recent trend towards improvement is to continue, it requires that the increased economic activities (notably the mining of oil and gas, petrochemical production, and incineration and dumping of chemical wastes) be kept sufficiently under control. A need is felt for a continued rational harmonization and planning of all activities on the North Sea. An even more stringent planning is required for the Wadden Sea which is now an international nature reserve under the Wetland Convention and is eligible for designation as a Biosphere Reserve under the UNESCO-MAB-programme. The river Rhine as greatest polluter of the North Sea and Wadden Sea urgently needs a clean-up.     

Bio-indicators and the quality of the Wadden Sea

The definitions of the notions bio-indicator and water quality are critically reviewed; it is shown that both have been used ambiguously.The quality of the Wadden Sea is discussed using a number of indicators for pollution effects; the Wadden Sea is now an unsuitable environment for a number of marine mammals, and, to a lesser extent, for some bird species. It cannot be shown whether or not this pollution has any effect on r-selective species.Paper presented at a Symposium held on 14 and 15 October 1982, in Utrecht, The Netherlands.     

Size effect on the mineralogy and chemistry of <Emphasis Type="Italic">Mytilus trossulus</Emphasis> shells from the southern Baltic Sea: implications for environmental monitoring

Mussels have the ability to control biomineral production and chemical composition, producing shells with a range of functions. In addition to biological control, the environment also seems to influence the process of biomineralization; thus, shells can be used as archives of ambient water parameters during the calcium carbonate deposition. Past and present environmental conditions are recorded in the shells in the form of various proxies including Mg/Ca or Sr/Ca ratios. For such proxies to be accurate and robust, the influence of biological effects including the size of studied organism must be examined and eliminated or minimized, so that the environmental signal can be efficiently extracted. This study considers mineralogy and elemental composition of shells representing four size classes of Mytilus trossulus from the Baltic Sea. Obtained results suggest that mineralogy and chemical composition change throughout the shell development due to most likely a combination of environmental and biological factors. The content of aragonite increases with increasing shell size, while the bulk concentrations of Na, Cd, Cu, U, V, Zn and Pb were found to decrease with increasing height of the shells. Therefore, using mussels for environmental monitoring requires analysis of individuals in the same size range.     

Time-Varying Parameter Analysis of the Baltic Sea Freshwater Runoffs

The Baltic Sea runoff events during 1970–2000 were analysed with non-linear estimation in order to find potential stability and time-varying (non-constancy) properties of time series parameters. In the Baltic Sea area, the wintertime rainfall is expected to increase, especially in the northern parts of the watershed; furthermore, seasonality is expected to decrease, i.e. the runoffs will become more evenly distributed over seasons, mainly by decreasing springtime peaks. We found a general increase in runoffs over the time period studied that consisted of a level shift upwards during the early 1980s. The runoffs considerably resulted from inputs in the months of April to June (which points to the significance of winter precipitation) and are biased to northern parts of the catchment. Our results suggest that this is connected with snow and ice melting in the northern areas of the watershed, especially in the subarctic catchment area of the Neva River (the area includes, for example, three of the four biggest lakes in Europe, Lake Ladoga, Lake Onega and Lake Saimaa, which are annually covered by ice). The yearly variation in runoff is significantly stabilised by large N–S extension of the watersheds of these lakes. The results are generally in accordance with the presented climatic expectations; however, decreasing seasonality was not obvious in the series yet. However, we found potential implications of system change towards decreased seasonality. By better understanding of ongoing processes in the sea, the results can give us an opportunity to better evaluate the system control, predicted areal consequences and ecosystem effects of the climate change. The analysis proved to be a sensitive tool for studying climatic variation in a relatively small area and over a short time span.     

Heavy Metals Monitoring using Bivalves from Mediterranean Sea and Red Sea

The concentrations of heavy metals (Cd, Co, Cu, Fe, Mn, Ni, Pd and Zn) were measured in the Bivalves (Modiolus auriculatus and Donax trunculus) collected from the Egyptian coasts of Mediterranean Sea and Brachiodonates sp. from the Egyptian coasts of Red Sea. The average concentrations of the heavy metals analyzed exhibited the following decreasing order: Fe > Zn > Cu > Mn > Ni > Co > Pb > Cd for both Mediterranean Sea and Red Sea. The analyses of Cd, Co, Ni, Pb, and Zn showed higher average concentrations for samples collected from Red Sea than that collected from Mediterranean Sea, while Fe, Cu and Mn showed the reverse results. Fe was used as a normalizing agent for all studied metals and exhibited presence of two locations from each of Mediterranean Sea and Red Sea have anthropogenic inputs of heavy metals. These results suggest that the coastal area in both Mediterranean Sea and Red Sea of Egypt might be considered relatively unpolluted with heavy metal.     

Aerial Monitoring of Marine Waterfowl in the Alaskan Beaufort Sea

The purpose of this study was to design and test a monitoring protocol for marine waterfowl in the central Alaskan Beaufort Sea. The study provides an important case-study of how a long-term monitoring program may be affected by unanticipated human disturbances.Because of its overwhelming and widespread abundance, relatively sedentary behavior, ease in counting, and the extensive historical database, the long-tailed duck (Clangula hyemalis) was selected as the focal species. Two null hypotheses were formulated concerning potential changes in the numbers and distribution of long-tailed ducks in relation to disturbance in an industrial study area, compared to a reference study area located about 50 km to the east.A 9-year historical database (1977–1984, 1989) of long-tailed duck densities and other important data recorded during systematic aerial surveys was analyzed retrospectively using multiple regression techniques. The retrospective analyses determined which of several predictor variables recorded were significantly related to long-tailed duck density. Separate analyses were conducted for two periods: (1) the overall period when long-tailed ducks were present in the lagoon study areas, and (2) the shorter adult male molt period. The results of the two analyses indicated that 57% and 68%, respectively, of the total variation in long-tailed duck density during the two periods could be explained by variables recorded during the surveys. Predictor variables representing habitat, day of the year, time of day, amount of ice, and wave height recorded on-transect during surveys were most closely associated with long-tailed duck density. Measurement error during the surveys, and influences outside the study area such as nesting success in tundra habitats and mortality during migration and in over-wintering areas likely also had strong influences on the results, but these factors were not measurable in our study.Based on results of the retrospective analyses, a long-term monitoring protocol consisting of a program of systematic aerial surveys and an analyses of variance and covariance (ANOVA and ANCOVA) statistical procedure was designed and initially tested in 1990 and 1991. This 2-year testing phase resulted in several revisions to the monitoring protocol. Refinements were made to the original sampling procedures, to the survey schedule, and to the recommended statistical analysis procedures. Results of the ANOVA and ANCOVA indicated that there was no evidence of a change in long-tailed duck densities that could be attributable to disturbance (from any source) in the industrial study area relative to a reference area with no industrial development. Other analyses indicated that the sampling and analysis procedures would be adequate to detect long-term trends in long-tailed duck density and localized disturbance effects, but that the monitoring program should be continued well beyond two years to detect statistically significant changes. As a result, additional aerial surveys of both study areas were conducted again during 1999–2001.Results of the revised ANOVA and ANCOVA of the 1990–1991 and 1999–2001 survey data indicated that the density of long-tailed ducks had significantly declined in coastal lagoons along the central Alaskan Beaufort Sea coast during the study period. In addition, disturbances throughout the barrier island-lagoon systems used by these ducks, including both the industrial and the reference study areas, had significantly increased over the same period. However, because unanticipated disturbances from a variety of anthropogenic sources, and not just industry sources, increased in both study areas, the reference study area was not an effective statistical control. As a result, the decline in long-tailed duck density in both study areas was not attributable to industry-related activities. Although the monitoring protocol described here is an effective method to detect statistically significant changes in long-tailed duck distribution and abundance in the nearshore Alaskan Beaufort Sea, many more years of sampling would be necessary to attribute observed changes to industry-related disturbances.     

渤海海域夏季大型底栖动物群落特征

根据2017年渤海海域47个站位大型底栖动物的调查资料,对该海域大型底栖动物进行了群落特征分析。调查共采集到大型底栖动物107种,研究海域大型底栖动物的平均密度为82 个/m²。优势种类分别为彩虹明樱蛤、不倒翁虫、长叶索沙蚕。聚类结果显示,渤海海域大致可按地理位置分为4个群落。与历史数据的对比显示,传统的较大个体的底栖种类,如棘皮动物、双壳类,已经被更小个体的多毛类、软体动物所取代,底栖动物的种类结构表现出了小型化的特征,这与近年来渤海海域底栖动物研究结果一致。研究表明,近年来受人类活动影响,渤海海域大型底栖动物群落结构已经发生了变化。     

Biological effects monitoring of the North Sea employing fish embryological data

Using the reproductive capacity of fish appears to be a suitable approach for risk assessment in the aquatic environment since fish are a typical representative thereof and in addition they are of considerable societal value. Generally the early embryonic stages are considered to be one of the most sensitive parts of a fish's life cycle. A method has been developed to use the state of health of live, naturally spawned fish embryos from plankton samples for biological effects monitoring. During the years 1985–1987 in the southern North Sea and in 1991–1992 in the whole of the North Sea fish eggs were sampled from surface waters and examined for developmental abnormalities. Elevated embryo malformation rates were detected in the plume of the major rivers Elbe and Rhine as well as along the eastern coast of England. Occurring malformations are thought to be pollution-related and may be used to define areas of environmental deterioration. The method is discussed in view of its suitability for biological effects monitoring using malformations in fish embryos as biomarkers.     

Relationships between trace elements in <Emphasis Type="Italic">Posidonia oceanica</Emphasis> shoots and in sediment fractions along Latium coasts (northwestern Mediterranean Sea)

The Mediterranean endemic seagrass Posidonia oceanica is widely used as a sensitive bioindicator of trace elements (TEs) in the coastal environment. Therefore, a bulk of data exist on TE levels from impacted versus unpolluted sites while only recent studies started comparing TE accumulation in plant compartments versus both water column and sediment characteristics. In this study, six TEs (As, Cd, Cr, Cu, Ni, Pb) were analyzed in P. oceanica shoots related to depth (?10 and ?20 m) and to TE concentrations in the different grain size fractions of the sediment, from two Sites of Community interest (SIC) in the central Tyrrhenian Sea. TE concentrations in both shoots and sediment were generally low, except for Cr. Cu was the only element showing significantly different concentrations at the two sites while As differed significantly between samples taken at different depths. TE concentrations in the unsieved sediment were found uncorrelated to TEs in shoots except for the important nutrient Cu (positive correlation). The finest sediment fractions were enriched in TEs and significantly correlated to Cd, Cr, Cu, and Ni concentrations in the shoots.     

Anthropogenic plutonium in the North Jiangsu tidal flats of the Yellow Sea in China

The ^239+240Pu activities and ²⁴⁰Pu/²³⁹Pu atom ratios were analyzed using a double-focusing SF-ICP-MS for sediment core samples obtained in 2007–2008 from the North Jiangsu tidal flats in the Yellow Sea in China. Particular attention was focused on the ²⁴⁰Pu/²³⁹Pu atom ratios in the sediment to identify the origins of Pu isotopes. The profiles of ^239+240Pu activities in the sediment cores are similar to those of the ¹³⁷Cs activities. The ²⁴⁰Pu/²³⁹Pu atom ratios in the tidal flats showed typical global fallout values, indicating that this area did not receive the possible early direct close-in fallout or oceanic current transported Pu from the Pacific Proving Grounds (PPG). If any, the contribution of the PPG source Pu to the total Pu inventory is negligible. This is different from the sediments in the Yangtze River estuary in the East China Sea, where the PPG source Pu contributed ca. 45 % to the total inventory. In addition, the observation of the global fallout origin Pu in the North Jiangsu tidal flats indicated that the nuclear power plant in the region was not causing any alteration/contamination to the ²⁴⁰Pu/²³⁹Pu atom ratios. The ^239+240Pu and ¹³⁷Cs activities/inventories in the sediment cores showed correlation to the mean clay sediment compositions (fine particles) in the tidal flats. Therefore, mud deposits are served as sinks for the anthropogenic radionuclides in the tidal flats and the Yellow Sea. Integrated with the previously reported spatial distributions of ^239+240Pu and ¹³⁷Cs activities in the surface sediments of the Yellow Sea, the mechanism of Pu transport with the ocean currents and the scavenging characteristics in the Yellow Sea were discussed.     

Trace metal monitoring of pelagic organisms from the open Mediterranean Sea

During the periods 1974–75 and 1977 mixed microplankton and individual species of macrozooplankton and nekton were sampled from a number of areas in the mediterranean Sea in order to establish baseline levels of selected trace elements in pelagic species from the open Mediterranean. Trace elements analyzed were Ag, As, Cd, Co, Cs, Cu, Fe, Hg, Mn, Rb, Sc, Se, V, and Zn. Variability for concentrations of many of the trace elements was high, and broadly speaking if trace element concentrations in all species examined from any one area in the Mediterranean are considered, no general regional differences in element levels were evident. On the other hand, metal concentrations in certain individual pelagic species did suggest limited regional variations. No significant differences between metal concentrations in organisms collected in 1974–75 and 1977 were noted. For most of the elements, similar data for the same species collected in other years do not exist, therefore at present it is not possible to establish temporal trends for metals in pelagic Mediterranean organisms. Comparison of these results with data reported for similar species from other oceanic regions suggests that metal levels in open ocean organisms are no higher in the Mediterranean than elsewhere. It is concluded that long-term, open ocean ecological monitoring programmes, while useful and possible to carry out technically, may be severely limited by the high costs of shiptime and lack of long-term commitment and financial support from both national and international bodies.     

Assessment of heavy metal enrichment in the offshore fine-grained sediments of the Caspian Sea

Sampling of the offshore seabed sediments of southwestern part of the Caspian Sea was carried out by gravity corer in order to study heavy metal concentration and the physicochemical factors controlling their distribution in the fine-grained fraction. The grain size distribution, amount, and type of clay minerals, total organic carbon (TOC) content, and Eh–pH of the sediments were determined. The average concentrations of the heavy metals in ppm are Mn (563), Cu (207.5), Sr (187), Zn (94), Pb (26.3), Ni (14.5), Co (11.5), Cd (2.56), and Ag (1.04) in their order of abundances. Co and Zn mostly indicate increase in silt-size fraction of the sediments suggesting their probable detrital provenance but the Mn, Ni, Cu, Sr, Pb, Cd, and Ag concentrations show a similar trend to distribution of the clay-size fraction. The concentrations of Mn, Co, and Cd increase with increase in the TOC content but the Cu, Pb, Ni, Ag, and Sr concentrations decrease with increase of the TOC content. The amounts of Zn, Cu, Sr, Pb, Cd, and Ag increase with increase in the CaCO₃ content. The calculated enrichment factor indicates that the sediments are very strong to extremely enriched in Ag, significantly enriched in Cu and Cd, and depleted to mineral for Pb, Sr, Co, Ni, and Zn. Variations of the Cu, Sr, Cd, Ag, and Pb concentrations are similar to the clay and CaCO₃ distributions.     

中国海域赤潮发生趋势的年际变化

回顾了中国海域的赤潮发生频次等数据的年际变化,尤其是进入21世纪的赤潮发生趋势,以期为赤潮灾害分析和防治提供帮助。数据表明,赤潮问题已不容忽视。总体上,赤潮发生的频次和累计面积呈现增长趋势,尤其是21世纪前10年的赤潮发生频次和规模是20世纪后50年的2倍多。与20世纪不同,东海的赤潮问题最严重,远远超过了南海;而渤海的赤潮规模也明显增加,此2海区成为赤潮的重灾区。赤潮多发生在5、6月份,但有延长的态势,对赤潮监测和预防提出了新的要求。赤潮生物,特别是有毒藻类不断增加,对渔业和人类健康造成威胁。同时也看到,赤潮的发生并非持续上涨,赤潮是可以防治的。     

Dinoflagellate bloom in tropical fish ponds of coastal waters of the South China Sea

Red tide of dinoflagellate was observed in brackish water fish ponds of Terengganu along the coast of the South China Sea during the study period between January 1992 to December 1992. The nearby coastal moat water facing the South China Sea is the source of water for fish pond culture activities of sea bass during the study period. An examination of water quality in fish ponds during the study period indicated that both the organic nutrients were high during the pre-wet monsoon period. The source of the nutrients in coastal water was believed to be derived from the agro-based industrial effluents, fertilizers from paddy fields and untreated animal wastes. This coincided with the peak production of dinoflagellate in the water column in October 1992. The cell count ranges from 8.3 to 60.4×10.4×10⁴/l during the bloom peak period and the bloom species were compared entirely of non-toxic dinoflagellates with Protoperidinium quinquecorne occurring >90% of the total cell count. However, both cultured and indigenous fish species were seen to suffer from oxygen asphyxiation (suffocation due to lack of oxygen). The bloom lasted for a short period (4–5 days) with a massive cell collapse from subsurface to bottom water on the sixth day. The productivity values ranged from 5–25 C g/ l / h with a subsurface maximum value in October 1992. Two species of Ciliophora, Tintinnopsis and Favella, were observed to graze on these dinoflagellates at the end of the bloom period.     

Trace elements (Cu,Zn, and Hg) and δ<Superscript>13</Superscript>C/δ<Superscript>15</Superscript>N in seabird subfossils from three islands of the South China Sea and its implications

Seabird subfossils were collected on three islands of the Xisha Archipelago, South China Sea. Via elemental analysis, we identified that bird guano was a significant source for heavy metals Cu, Zn, and Hg. Cu and Zn levels in these guano samples are comparable to their levels in wildbird feces, but guano Hg was lower than previously reported. Trophic positions significantly impacted transfer efficiency of heavy metals by seabirds. Despite of a common source, trace elements, as well as stable isotopes (i.e., guano δ¹³C and collagen δ¹⁵N), showed island-specific characteristics. Bird subfossils on larger island had relatively greater metal concentrations and revealed higher trophic positions. Partition of element and isotope levels among the islands suggested that transfer efficacy of seabirds on different islands was different, and bird species were probably unevenly distributed among the islets. Island area is possibly a driving factor for distributions of seabird species.     

Major and trace elements’ concentrations in hard and soft tissues of kutum, <Emphasis Type="Italic">Rutilus kutum</Emphasis>, from the Caspian Sea and their potential use as biomonitoring tools

The potential use of different hard and soft parts (otolith, scale, eye lens, dorsal spine, vertebral bone, muscle, and liver) of Rutilus kutum for biomonitoring of 13 major and trace elements (Br, Ca, Cl, Cu, Fe, K, Mg, Mn, Na, P, S, Sr, and Zn) was evaluated, for the first time. The specimens were sampled from three sampling sites in the Southern Caspian Sea in May 2016. Twenty specimens were collected from each site. The elements’ concentrations in the samples were measured by proton-induced X-ray emission (PIXE). In all the hard tissues, except for eye lens, Ca was the most abundant element, whereas Fe was among the least abundant elements. The orders of element occurrence in the two soft tissues were largely similar. Ca, Fe, S, Cl, and K could be detected in all the selected tissues, while Br was detectable only in otolith. Minor similarities among the tissues were identified in the case of eye lens (concerning P, S, and Zn) and liver (in terms of Cl, Fe, and K), whereas, in the case of Sr and Ca, otolith shows the maximum distance. In general, it can be concluded that all the studied hard parts, except for eye lens, may offer alternatives for biomonitoring of Ca, Cl, Fe, K, and S in the southern Caspian Sea. The scales and spines represent a potential non-lethal alternative to the other hard parts.     

Metal Concentrations in Fish Species from the Northeast Mediterranean Sea

Samples of Mugil cephalus and Mullus barbatus were collected in the Northeast Mediterranean coast of Turkey the contents of cadmium, copper, iron, zinc and lead in the liver, gill and muscle tissues were determined by atomic absorption flame spectrophotometry.Except for lead, highest levels of each metal were found in the liver and this was followed by the gill and muscle in both species. Among the metals analyzed, Cu, Zn and Fe were the most abundant in the different tissues while Cd and Pb were the least abundant both in M. cephalus and M. barbatus. Seasonal changes in metal (Cd, Cu, Pb, Fe and Zn) concentration were observed in the tissues of both species, but these seasonal variations may not influence consumption advisories. In general, the highest concentrations were detected for all metals in summer.     

Coral communities of the remote atoll reefs in the Nansha Islands, southern South China Sea

During the months of May and June in the year 2007, a survey was conducted regarding coral reef communities in the remote atolls (Zhubi Reef and Meiji Reef) of Nansha Islands, southern South China Sea. The goals of the survey were to: (1) for the first time, compile a scleractinian coral check-list; (2) estimate the total richness, coral cover, and growth forms of the community; and (3) describe preliminary patterns of community structure according to geomorphological units. Findings of this survey revealed a total of 120 species of scleractinia belonging to 40 genera, while the average coral cover was 21 %, ranging from less than 10 % to higher than 50 %. Branching and massive corals were also found to be the most important growth forms of the whole coral community, while Acropora, Montipora, and Porites were the three dominant genera in the overall region, with their contributions to total coral cover measuring 21, 22, and 23 %, respectively. Overall, coral communities of the Nansha Islands were in a relative healthy condition with high species diversity and coral cover. Spatial pattern of coral communities existed among various geomorphological units. Mean coral cover was highest in the patch reef within the lagoon, followed by the fore reef slope, reef flat, and lagoon slope. The greatest contributors to total coral cover were branching Acropora (45 %) in the lagoon slope, branching Montipora (44 %) in the reef flat, and massive Porites (51 %) in the patch reef. Coral cover in the fore reef revealed a greater range of genera than in other habitats. The leeward fore reef slope had higher coral cover (>50 %) when compared with the windward slope (<10 %). The coral communities of the inner reef flat were characterized by higher coral cover (27 %) and dominant branching Montipora corals, while lower coral cover (4 %) was dominated by Psammocora with massive growth forms on the outer reef flat. Destructive fishing and coral bleaching were two major threats to coral communities in the study area.     

Occurrence of potential bacterial pathogens in coastal areas of the Adriatic Sea

A monitoring program was carried out in bathing waters along the sea-coast of the Adriatic Sea. The investigation was aimedat obtaining a quali-quantitative picture of microorganisms ofanthropic origin and of a more strictly autochthonous origin and at verifying the existence of possible reciprocal correlations and combinations of relationship between them. Results showed that the concentrations of indicators of faecal contamination, whether within or over the values established by legislation, are not always related to the presence and density of microorganisms of environmental origin but the regression modelsused can help to describe how these latter microorganisms can bein relation to levels of the other parameters. The difficultyis evident of the predictability of health effects swimming-associated; for this reason more complex models that are currently used should be taken into account for minimising the risk for bathers.     

Hydrographic characterization of southeast Arabian Sea during the wane of southwest monsoon and spring intermonsoon

Seasonal variation of the hydrography along the southeast Arabian Sea is described using data collected onboard FORV Sagar Sampada in September–October 2003 (later phase of Southwest monsoon, SWM) and March–April 2004 (Spring inter monsoon, SIM). During the later phase of the SWM, upwelling was in the withdrawal phase and the frontal structure was clearer in the northern sections (13 and 15°N lat) indicating strong upwelling in the area. The driving force of upwelling is identified as the combination of alongshore wind stress and remote forcing with a latitudinal variability. Although a more prominent upwelling was found in the north, a maximum surface Chlorophyll-a was found in the south (10°N). During the SIM, the area was characterized by oligotrophic water with relatively high Sea Surface Temperature (>29°C) and low salinity (33.8 to 35.4). During March, the surface hydrography was found to be controlled mainly by the intrusion of low-saline waters from the south, while during September by the high saline water from the north. The presence of various water masses [Arabian Sea High Salinity Water (ASHSW), Persian Gulf Water (PGW), Red Sea Water (RSW)] and their seasonal variations in the region is discussed and their decreasing influence towards the south is noted during both periods of observation. During the SWM, the dynamic topography showed the equator-ward flow of the West India Coastal Current (WICC) at the surface and a pole-ward coastal under current at sub-thermocline depth. During the SIM, surface circulation revealed the WICC flowing pole-ward north of 13°N, but equator-ward flow in the south, with a clockwise circulation around the Lakshadweep High.