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1.
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2.
In Belgium, centralized reporting on landings of sea fisheries at the species level started in 1929. This paper summarizes the process and the results of integrating time-series, based on fragmented and disperse data sources for the period 1929–1999. The resulting database contains data by species (41), by port of landing in Belgium (4) and in ‘foreign ports,’ and by fishing area of origin (31). After quality control, total reported landings over the period 1929–2008 amounted to 3,320,518 tonnes, of which 90% was landed in the Belgian ports. After a maximum of 75,370 tonnes in 1947, annual landings declined steadily to only 26% of this peak by 2008. Currently, landings are below those achieved in 1929. The most important species in terms of landings (1929–1999) were cod (17% of all landings) and herring (16%). In terms of economic value, sole (31%) and cod (15%) were the most valuable. Close to 73% of all landings originated from 5 of the 31 fishing areas. Twenty percent of all landings (1929–1999) originated from the ‘coastal waters’, while these waters contributed nearly 60% of all landed pelagic species and 55% of all landed ‘molluscs and crustaceans’. Compared to the currently available ICES data, this local database offers advantages in temporal coverage (data from 1929 onwards), temporal scale (monthly values), and at the taxonomic level. It also provides more detailed information at the spatial scale of the southern and central North Sea, and it is the only source of historical information on landings originating from the coastal waters. Given the importance of the shallow and productive ‘Flemish banks’ as a local source of food in historical and recent times, this data is valuable for further research on the productivity of the coastal ecosystem and the local impact of fisheries. The database broadens the historical view on fisheries, underlines the decline in landings since reporting started, and serves as a basis for further (fisheries) research and policy-making in Belgium.  相似文献   

3.
Within the Land Ocean Interactions in the Coastal Zone (LOICZ)-Basins approach, the Magdalena River Project (MRP) is an interdisciplinary research, which aims to improve the scientific understanding of the linkages between the Magdalena drainage basin and its associated coastal environments. The MRP is an outgrowth of the initial regional planning that resulted from the LOICZ South American Basins (SamBas) and Caribbean Basins (CariBas) studies on land use and hydrological changes during approximately the past century in tropical and temperate benchmark river basins. The results of the MRP presented in this article show that the extent of land-cover change and erosion within the catchment has increased over the last 10–20 yr. The overall increasing trends in sediment load on a regional scale may be attributed to a range of anthropogenic influences including: a 40% decrease in forests over a 20-yr period; a 65% increase in agricultural and pasture; poor practices of land use; mining; and increasing rates of urbanization. These increasing trends in sediment load coincide with the overall decline of live coral cover in a 145-km2 coral reef complex in the Caribbean Sea. In addition, the impacts of heavy sediment loads and freshwater discharges have greatly contributed not only to the total disappearance of coral formations but also to a considerable reduction in abundance of seagrass beds in Cartagena Bay and neighbouring areas. The synthesis and analysis presented in this article are just first steps toward understanding the natural and human-induced factors that have produced the observed patterns of water discharge and sediment load of the Magdalena River into the Caribbean Sea, and to relating these processes to the impact on coastal ecosystems.  相似文献   

4.
This paper replies to TE Baldock's discussion [Coastal Eng. 56 (2009) 380–381] of ‘Measurement of wave-by-wave bed-levels in the swash zone’ by Turner et al. [Coastal Eng. 55 (2008) 1237–1242]. We address and extend the comparison and discussion of ultrasonic bed-level sensors and buried pressure transducers to obtain estimates of the beach face elevation within the swash zone. We demonstrate the use of the former method to obtain many and continuous (every time the beach face is exposed) in-situ estimates of net sediment flux per swash.  相似文献   

5.
It is generally assumed that estuarine mixing is continuous for metals from terrestrial sources, gradually decreasing towards the open ocean endmember. Here we show that, chemical reactivity, determined by ion exchange method, and molecular weight distributions, obtained using cross-flow ultrafiltration, of dissolved Cd, Cu, and Ni in the surface waters of the Gulf of Mexico varied systematically across the estuarine mixing zone of the Mississippi River. Most size or chemical affinity fractions of dissolved metals (<0.4 μm) were linearly related to salinity (10.8–36.6), suggesting that the distribution of these elements was mainly controlled by continuous mixing processes. Dissolved concentrations across the salinity gradient ranged for Cd: 87–187 pM; Cu: 1.4–18.3 nM; and Ni: 2.6–18.8 nM, with highest values near the Mississippi river mouth, and lowest concentrations in a warm core ring in the Gulf of Mexico. Dissolved Cd was mostly present as a truly dissolved (<10 kDa, 97 ± 1%) and cationic fraction (Chelex-100 extractable, 94 ± 4%). A novel observation across the estuarine mixing zone was that colloidal metal concentrations were identical to either inert (for Cu, Ni) or AMPG-labile anionic (Cu, Cd) fractions. The difference in behavior between Cu and the other two metals might indicate differences in the biopolymeric nature of the metal–organic chelates. In particular, the anionic-organic Cd fractions accounted for just 3 ± 1%, on average. However, for Cu, it was 24 ± 4%, and for Ni, it was 9 ± 6%. The fractions of the total dissolved metal fractions that were “inert” averaged 31 ± 10% for Cu and 29 ± 12% for Ni. Small but noticeable amounts (6 ± 3%) of dissolved inert Cd fractions were also present. Apparent non-local transport processes, likely associated with cross-shelf sediment resuspension processes, could have been responsible for the relatively high concentrations of ‘inert’ and ‘anionic’ metal fractions in high salinity coastal waters, and accounting for the persistence of metals bound to humic substances in the Gulf of Mexico.  相似文献   

6.
This Special Issue reflects work developed during and following the execution of the Science and Policy Integration for Coastal System Assessment project. Theoretical and practical outcomes of case studies have been of direct relevance to coastal management not only at local but also at a European scale. Papers included here consider the long term legacy of the project for academics and practitioners involved specifically in integrated coastal zone management. These align to two themes, the first focussing on the generic application of the Systems Approach Framework to coastal management and the second focussing on the specific application of the approach at case study sites.  相似文献   

7.
While coastal management activities have long been known to exert a strong influence on the health of marine ecosystems, neither scientists nor administrators have realized that small interventions may lead to disproportionately larger impacts. This study investigated the broad and long-lasting environmental consequences of the construction of an ill-planned, although small (only 12 m long) jetty for pleasure crafts on the hydrodynamic conditions and on the meadow of the seagrass Posidonia oceanica of an embayed cove in the Ligurian Sea (NW Mediterranean). There, P. oceanica used to develop on a high (>1.5 m) matte (a lignified terrace causing seafloor elevation) in which the leaves reach the surface and form a compact natural barrier to waves in front of the beach. Such a so-called ‘fringing reef’ of P. oceanica is today recognized of high ecological value and specific conservation efforts are required. The construction of the jetty implied the cutting of the matte, which directly destroyed part of the fringing reef. In addition, meadow mapping and sedimentological analyses coupled with morphodynamic modelling showed that the ecosystem of the whole cove had been greatly altered by the jetty. We used the geometric planform approach, a proper tool in the study of headland-controlled embayment, both to characterise the present situation of Prelo cove and to simulate the original one, before the jetty was built. In the long term, such a small jetty completely altered the configuration and the hydrodynamic conditions of the whole cove, splitting the original pocket beach into two smaller ones and creating strong rip-currents flowing seaward along the jetty. These rip-currents enhanced erosion of residual shallow portions of the meadow and further modified the sedimentary fluxes in shallow waters. A century after the construction of the jetty, an irreversible environmental damage has occurred, as the slow growing rate of P. oceanica implies that the high matte terrace and the fringing reef will hardly form again, even after the removal of the jetty. The lesson learnt from this study is that even such small, and therefore reputed intrinsically ‘innocent’, interventions on the coastal zone require accurate planning based on interdisciplinary studies to understand and respect the delicate interplay among morphological, hydrodynamic and ecological components.  相似文献   

8.
The use of barnacles as biomonitors of metal contamination in coastal waters worldwide is reviewed as a critique compilation of the reported studies and presents resume-tables of available data for future reference. The barnacle body reflects both short and long-term metal level environmental variations and the metal bioaccumulation occurs mainly in their granules (relatively inactive pools). The barnacle body is considered as good biomonitoring material and different barnacle species could bioaccumulate metal concentration ranges of 40–153,000 μg/g of Zn, 20–22,230 μg/g de Fe, 1.5–21,800 μg/g of Cu, 5.9–4742 μg/g of Mn, 0.1–1000 μg/g of Pb, 0.7–330 μg/g of Cd, 0.4–99 μg/g of Ni and 0.2–49 μg/g of Cr. However, as the plates (‘shells’) of barnacle exoskeletons can be affected by metal levels in coastal waters, mainly in their composition and morphology, they are not considered good biomonitoring material. Despite this, the use of a specific barnacle species or group of species in a specific region must firstly be carefully validated and the interpretation of the contaminant bioaccumulation levels should involve specific environmental variations of the region, physiological parameters of the barnacle species and the relationship between the potential toxicity of the contaminant for the environment and their significance for the barnacle species. Barnacles, particularly a widespread cosmopolitan species such as Amphibalanus amphitrite, have a great potential as biomonitors of anthropogenic contamination in coastal waters and have been used worldwide, including Europe (United Kingdom, Turkey, Poland, Croatia, Spain and Portugal), Asia (India and China), Oceania (Australia), North America (Florida, Massachusetts and Mexico) and South America (Brazil). The use of barnacle species as biomonitors of metal contamination in coastal waters is considered an important and valuable tool to evaluate and predict the ecological quality of an ecosystem.  相似文献   

9.
Managed realignment (MR) is a ‘soft’ engineering technique that involves the deliberate landwards retreat of the existing line of coastal defence and subsequent tidal inundation of land. Managed realignment has been established worldwide for over 30 years and its goals may include habitat restoration, recovery of biodiversity and sustainable coastal defence. In southeast England in particular, an increasing number of MR sites (20–110 ha) have been commissioned in the last decade in response to increasing coastal habitat loss and sea-level rise. Following initial sea wall breaching and site flooding, monitoring of these sites is usually carried out for a period of 5 years and during this time changes in ecosystem structure can be easily observed. However, there is a poor understanding of the long-term effects of flooding on soil physicochemical parameters including sediment geochemistry and geochemical cycling, nutrient fluxes and soil maturation processes. Such physical and chemical changes may continue to take place over time-scales exceeding 5 years and therefore current monitoring practices may not be sufficient.  相似文献   

10.
For much of the last century, the prerequisites for establishing a new primary industry were property rights to secure access to the required natural resources, the appropriate technology, brood stock and labour, and a willing investor. In contrast, in many western nations although all these prerequisites have been in place for the establishment of new coastal marine farming sectors, fledgling aquaculture operations have failed to establish. A prime reason for this is that under increasingly consultative integrated coastal zone management regimes, local stakeholders are expressing a desire for prospective aquaculture operations to demonstrate that they will be sustainable. Many potential marine farmers and regulatory authorities have stumbled on this demand and the work presented here aims to elucidate the nature of sustainability in a coastal aquaculture context and provide a framework for investigating these critical ‘non-traditional’ factors limiting the establishment and development of coastal aquaculture activities.  相似文献   

11.
‘Human-dolphin (Tursiops truncatus Montagu, 1821) cooperative fishery’ and its influence on cast net fishing activities in Barra de Imbé/Tramandaí, Southern Brazil - aims to describe ‘fishing with dolphins’ or ‘botos’ (Tursiops truncatus Montagu, 1821), its importance in mullet fishing in conjunction with the traditional knowledge of artisanal fishermen, and the negative economic impact that tourism has had on mullet fishing in Barra de Imbé/Tramandaí (29°58′S 50°07′W). In November and December of 2009, 22 artisanal fishermen associated with the Tramandaí Fishermen’s Union were interviewed. During these interviews, questionnaires were employed utilizing both open and closed questions that dealt with behavioral ecology, biological and interactional issues related to bottlenose dolphins, and small-scale fishing in the region. All those interviewed described “boto fishing,” in which bottlenose dolphins “helped out the fishermen.” According to these interviews, this kind of fishing, marked by close interaction between humans and ‘botos,’ allows nets to be cast fewer times and with captured fish yields that are greater than, when there is no dolphin is present. The fishermen maintain that this increased productivity results from ‘botos’ showing them exactly where the schools of fish are located below the water surface. This has made it possible to observe the impact that dolphin fishing has on the monthly incomes of these fishermen, and there is concern among fishermen, that the intense tourism may one day contribute to the disappearance of the ‘boto,’ a situation, they believe would negatively affect their fishing activities.  相似文献   

12.
Fisheries have long been managed through public–private partnerships based on collaboration between government and user-groups. The alleged benefits of involving the latter—as representatives of civil society—are a management system that is more flexible and legitimate than one based exclusively on top–down command and control. A question that is rarely addressed is whether civil society is up to the task. Are voluntary associations fit—‘technically’ and ‘democratically’—to take on management responsibilities? Assessing the pros and cons of involving civil society in fisheries governance requires a closer look at the role of user-groups in public policy-making. This paper attempts to do that by examining certain aspects of the Norwegian system of fisheries management, focusing—in particular—on the role of its most prominent civil society player: the Norwegian Fishers’ Association. The association has long been a privileged partner, virtually monopolizing the attention and goodwill of government. How has this been justified, and does it still serve its original purpose? As the fishery has changed, so—we contend—has the association: from something akin to a public interest group into what is essentially a ‘trade union’ pursuing the economic interests of its most powerful members. How and why did this change—in goals and priorities—come about, and is it tenable that this particular partnership continues? What lessons, if any, can be drawn from the Norwegian case about the pros and cons of user involvement, interactive governance and the role of civil society in fisheries management?  相似文献   

13.
The eastern part of the Mediterranean coast of Morocco is physically and socio-economically vulnerable to accelerated sea-level rise, due to its low topography and its high ecological and touristic value. Assessment of the potential land loss by inundation has been based on empirical approaches using a minimum inundation level of 2 m and a maximum inundation level of 7 m, where scenarios for future sea-level rise range from 200 to 860 mm, with a ‘best estimate’ of 490 mm. The socio-economic impacts have been based on two possible alternative futures: (1) a ‘worst-case’ scenario, obtained by combining the ‘economic development first’ scenario with the maximum inundation level; and (2) a ‘best-case’ scenario, by combining the ‘sustainability first’ scenario with the minimum inundation level. Inundation analysis, based on Geographical Information Systems and a modelling approach to erosion, has identified both locations and the socioeconomic sectors that are most at risk to accelerated sea-level rise.  相似文献   

14.
A new methodology to classify European North-East Atlantic transitional waters into ecological types has been developed based on the most important hydrological and morphological features that are likely to determine the ecology of aquatic systems in transitional waters. Hydrological indicators help identifying if a transitional water area is dominated by fresh or sea water and/or by intertidal or subtidal areas, while morphological indicators allow an estimation of the complexity of the transitional water and the diversity of the habitats involved. Twelve transitional waters of the southern Bay of Biscay were classified using this methodology and the five hydro-morphological types obtained were validated with benthic macro-invertebrate data. Transitional waters with a complex morphology showed the highest values of species diversity, while those with a smaller tidal influence showed lower species diversity. The ‘Scrobicularia’ and ‘Abra’ assemblages, previously identified in the study area, were found to be related to different types of transitional waters. The ‘Abra’ assemblage only appeared in estuaries with a complex morphology and dominated by tidal influences, while the ‘Scrobicularia’ assemblage was detected in all the transitional waters except for a single coastal lagoon. This classification of transitional waters may therefore be useful to establish the biological reference conditions needed for European Directives.  相似文献   

15.
The shingle (gravel) barrier beach at Pevensey Bay (East Sussex, UK) protects rare habitat, properties, trunk roads and other assets from flooding and erosion. The beach is managed in an adaptive manner by a private consortium, based on a 25 year contract. The practices developed at Pevensey are shown to fit into the frame of reference approach, adapted for the English policy and management framework. The barrier beach is managed to retain a favourable sediment status, although the concept has no official recognition, thereby ensuring that the barrier is sufficiently resilient to maintain its functions between interventions. The concept of favourable sediment status is considered a potentially useful way of summarising the status of the beach at Pevensey as it combines management objectives and processes (through coastal state indicators) with the availability of supply. The concept of the coastal sediment cell is important, but not sufficient, for identifying policy units at Pevensey as smaller-scale processes are also important. Two offshore dredging areas constitute the strategic sediment reservoir for Pevensey, although the term ‘strategic sediment reservoir’ has no official recognition and there is no long-term guarantee of supply.  相似文献   

16.
Dynamics of Turbidity in the Tweed Estuary   总被引：1，自引：0，他引：1  
Results are presented of turbidity measurements made in the Tweed Estuary during 14–29 September 1993. The observations covered a spring-neap period of very strong and relatively weak tides, which included strong wave activity at the mouth of the estuary, the aftermath of a strong freshwater inflow event and a minor inflow event which coincided with neap tides. Turbidity levels between the mouth and the limit of saline intrusion during this period were observed to lie in the range 2–30 ppm. Temperature–salinity relationships, based on rapid sampling throughout the estuary, often indicated conservative mixing between riverine and coastal waters. Turbidity–salinity relationships throughout the estuary were approximately linear for most of the lower salinity range (<30) although the relationships varied throughout a tidal cycle. At the highest salinities, in the lower 2·5 km of estuary, significantly enhanced turbidities occurred during strong, onshore swell-wave conditions. Near-mouth turbidities were very low (<5 ppm) at high-water (HW) when the swell-wave height was small (<0·3 m). There was no correlation between near-mouth turbidity at HW and tidal range, whereas the correlation between near-mouth turbidity and swell-wave height explained over 90% of the variance in near-mouth turbidity. The temporal trends in freshwater turbidity and freshwater inflow during the fieldwork period were fairly similar. A statistically significant relationship existed between these variables when freshwater turbidity was correlated against inflow 30 h earlier. A ‘ model ’ of turbidity, based on 5 days of inflows and used to hindcast turbidity from 14 days of inflows between 16–29 September, explained over 80% of the variance in freshwater turbidity. Therefore, inflow exerted a significant control on the fluvial turbidity. It appears that very fine-grained particles were responsible for the observed turbidity in the central and upper reaches of the Tweed. During the flood, in the presence of strong wave activity in the coastal zone, larger sediment was rapidly winnowed in the lower reaches, close to the mouth, whereas fine silt particles remained in suspension and reached the limit of saline intrusion.  相似文献   

17.
The physicochemical and biological characteristics of coastal waters form a gradient extending from land to ocean. In the Mediterranean this gradient is particularly large, due to the sea’s weak tides. Within coastal waters, those waters in contact with land are called coastal inshore waters (CIW), defined herein as between 0 and 200 m from the shoreline. Here we present the first physicochemical and biological characterization of CIW of the NW Mediterranean Sea. This case study is based on 19 years of data collected from coastal inshore (CIW; 0–200 m), nearshore (CNW; 200–1500 m), and offshore (COW; >1500 m) waters of the Catalan coast. Analyses of these data showed that the physicochemical and biological characteristics of CIW differ significantly from those of CNW and COW due to: (1) significantly higher concentrations of dissolved inorganic nutrients (nitrate = 11.07 μM, nitrite = 0.52 μM, ammonium = 6.43 μM, phosphate = 0.92 μM, silicates = 5.99 μM) and chlorophyll-a (=2.42 μg/L) in CIW than in either CNW or COW (in some cases up to one order of magnitude); (2) a greater variability of dissolved inorganic nutrients and chlorophyll-a in CIW than in CNW and COW, and (3) the presence of a mostly urban population and the effects of river inflows as a primary source of CIW variability but with minimal impact on CNW or COW. In addition, the risk of eutrophication was found to be highest in CIW, placing human and environmental interests at greater risk than in the outermost coastal waters. The results highlight the importance of considering the distinctive physicochemical and biological properties of CIW in future coastal waters studies. This is of major importance in assessments of eutrophication and coastal water quality, not only to identify the pressure–impact relationships but also to allow the timely detection of local environmental problems and thus avoid endangering the unique communities of CIW and ensuring the sustainability of human activities. In conclusion, CIW characterization is essential to integrate coastal zone management.  相似文献   

18.
In order to develop a policy framework and guidelines for improving a national approach to the management of Irish coastal regions and associated resources one first needs to be able to define what is meant by ‘a coastal region’ in an Irish context and secondly to know how the socio-economic characteristics of Irish coastal populations differ from the national perspective. This paper is therefore concerned with the coastal economy and the socio-economic characteristics of Ireland's coastal regions. These coastal regions are defined at a number of alternative levels of spatial aggregation. The compilation of coastal economic data is important when one considers the recommendations of the European Council and Parliament concerning the implementation of Integrated Coastal Zone Management and the requirements of policies such as Integrated Maritime Policy for the European Union and the EU Marine Framework Strategy Directive.  相似文献   

19.
A ‘quasi-island’ approach for examining the meridional flux of warm and intermediate water from the Southern Ocean into the South Atlantic, the South Pacific and the Indian Ocean has recently been proposed ( [Nof, 2000a] and [Nof, 2002]). This approach considers the continents to be ‘pseudo islands’ in the sense that they are entirely surrounded by water, but have no circulation around them. The method employs an integration of the linearized momentum equations along a closed contour containing the continents. This allows the meridional transport into these oceans to be computed without having to find the detailed solution to the complete wind-thermohaline problem.The solution gives two results; one expected, the other unexpected. It shows that, as expected, about 9±5 Sv of upper and intermediate water enter the South Atlantic from the Southern Ocean. The unexpected result is that the Pacific-Indian Ocean system should contain a ‘shallow’ meridional overturning cell carrying 18±5 Sv. What is meant by shallow here is that the cell does not extend all the way to the bottom (as it does in the Atlantic) but is terminated at mid-depth. (This reflects the fact that there is no bottom water formation in the Pacific.) Both of these calculations rely on the observation that there is almost no flow through the Bering Strait and on the assumption that there is a negligible pressure torque on the Bering Strait’s sill.Here, we present a new and different approach, which does not rely on either of the above two conditions regarding the Bering Strait and yet gives essentially the same result. The approach does not involve any quasi-island calculation but rather employs an integration of the linearized zonal momentum equation along a closed open-water latitudinal belt connecting the tips of South Africa and South America. The integration relies on the existence of a belt (corridor) where the linearized general circulation equations are valid. It allows for a net northward mass flux through either the Sverdrup interior or the western boundary currents. It is found that the belt-corridor approach gives 29±5 Sv for the total meridional flux of surface and intermediate water from the Southern Ocean. This agrees very well with the quasi-island calculations, which give a total northward flux of 27±5 Sv. Given the spacing between the continents and the small variability of the southern winds with longitude, one may assume that 9 Sv of the total 29 Sv enters the Atlantic and the other 20 Sv enters the combined Pacific-Indian Ocean system, which is also in agreement with the quasi-island calculation. These agreements indicate that the assumptions made in the earlier studies regarding the Bering Strait are probably valid.  相似文献   

20.
Unselective fishing catches non-target organisms as ‘bycatch’—an issue of critical ocean conservation and resource management concern. However, the situation is confused because perceptions of target and non-target catch vary widely, impeding efforts to estimate bycatch globally. To remedy this, the term needs to be redefined as a consistent definition that establishes what should be considered bycatch. A new definition is put forward as: ‘bycatch is catch that is either unused or unmanaged’. Applying this definition to global marine fisheries data conservatively indicates that bycatch represents 40.4 percent of global marine catches, exposing systemic gaps in fisheries policy and management.  相似文献   

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