摘要:

Abstract1.A 4‐year study developed methods for annual monitoring of shallow‐water tropical marine benthic communities to detect changes in spatial patterning and benthic diversity. Two low‐relief sponge/octocoral communities were selected from natural colour photography to gain a broader perspective on spatial variability in the benthic community structure of similar community types.2.Changes in benthic spatial patterning were studied using four methods: (i) substrata and lifeform coverage characterization, (ii) species inventories, (iii) belt quadrat measurements of taxa‐level (algae, sponges, octocorals and stony corals) density, area coverage and size, and (iv) belt quadrat measurements of species‐level density, area coverage and area per individual or colony.3.A sampling hierarchy of multiple parameters was utilized to detect changes in benthic community diversity. Substrata and lifeform characterizations (at the taxa‐versus species‐level) were the least sensitive and serve as indicators of catastrophic change in community structure.4.Changes in spatial patterning of the benthos that may be attributed to low‐level, chronic anthropogenic disturbances can be best studied utilizing belt quadrat measurements. The use of multiple study sites and a sampling hierarchy was useful in minimizing Type II errors and to determine the level of monitoring necessary to segregate natural rates of change from anthro

ISSN:1052-7613    

DOI:10.1002/aqc.3270030303

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

摘要:

Abstract1.A visual assessment method, called Discrete Group Censusing, was used to assess and monitor five coral reef fish assemblages in the Key Largo National Marine Sanctuary, Florida, USA.2.Samples were obtained quarterly from Winter 1988 to Autumn 1990 to investigate a possible relation between the variability of reef fish assemblages and human disturbance.3.Two types of disturbance were studied: a ship grounding that occurred 4 years previous to the study, and intensive, recreational snorkel and SCUBA diving. These disturbances appeared to have no short‐term effect on the temporal variability of the reef fish assemblages during the study period.4.Furthermore, the assemblages at all five study sites appeared to be extremely stable over the 2 year period of the study. These results support the theory that coral reef fish assemblages are highly ordered and stable over relatively large spatial scales.5.The Discrete Group Censusing visual assessment method was found to be a valuable and easily applied tool for the nondestructivein situmonitoring of reef fish assemblages on coral reef

ISSN:1052-7613    

DOI:10.1002/aqc.3270030304

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

摘要:

Abstract1.Entanglement in gillnets constitutes the greatest known threat to populations of small cetaceans. In 1988, in response to data on the distribution and abundance, incidental catch, reproduction and population biology of Hector's dolphins, and after an extended period of public consultation, New Zealand's Department of Conservation created a 1170 km2Marine Mammal Sanctuary. Within this area, gillnetting on a commercial scale is illegal and amateur fishers may only set gillnets in specific times and places.2.This paper summarizes the salient points of research that led to the creation of the sanctuary, briefly describes the process by which the sanctuary was established, and offers some comments on the information required for conservation management of small cetaceans.

ISSN:1052-7613    

DOI:10.1002/aqc.3270030305

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

摘要:

Abstract1.The topmouth gudgeonPseudorasbora parvaSchlegel, 1842, a south‐east asian cyprinid, was introduced accidentally in the Danube Delta in Romania in the 1960s and has now achieved a pan‐Danubian distribution.P. parvahas been introduced into other countries, such as Greece, usually inadvertently included with other species imported for fish farming. In 1984–85, during a study of the fish populations of Lake Mikri Prespa (north‐west Greece), several topmouth gudgeon were caught. Our aim was to study the changes in the population size ofP. parvaover nearly 10 years, to study its life history traits and to assess its potential impacts on native fish species.2.The catch per unit effort (CPUE) in spring increased significantly between 1984 and 1992. We found evidence thatP. parvahas established a breeding population in the lake.P. parvacombines many characteristics likely to favour a successful colonization (resistance to harsh climatic conditions, early sexual maturity, extended breeding season, broad dietary spectrum). Growth in Lake Prespa, where the oldest individuals captured were 3 years old, is very similar to that observed within its native range.3.There is evidence for dietary overlap betweenP. parvaand three endemic species:Paraphoxinus epiroticus prespensis, Cobitis meridionalis and Alburnoides bipunctatus ohridanus. No decline in the populations of these three species has yet been demonstrated. Other possible impacts are discussed. The successful colonization byP. parvawas certainly favoured by the absence of a true piscivorous fish in the lake and by the isolation and high level of endemism of fish communities.4.The conservation of the many endemic species in the lake should be a priority and the introduction of exotic species should be

ISSN:1052-7613    

DOI:10.1002/aqc.3270030306

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

摘要:

Abstract1.A biological inventory is described for Portelet Bay, on the south coast of Jersey in the Channel Islands, which has been selected for the Island's first marine nature reserve.2.The application of site assessment criteria in justifying the selection of the site is discussed.3.Conclusions are drawn on the process by which marine reserve status might be achieved.

ISSN:1052-7613    

DOI:10.1002/aqc.3270030307

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

摘要:

Abstract1.The efficacy of strategies to reduce external nutrient loads to eutrophicated lakes may be evaluated using the example of Slapton Ley, a freshwater Site of Special Scientific Interest in south‐west England.2.The results of this study suggest that, in dealing with eutrophication, a reduction in point‐source loads is important, but attention must also be given to non‐point, agricultural sources.3.One measure which would appear to be effective against diffuse nutrient export from farmland involves the creation of woodland buffer zones along the courses of the rivers draining into the Ley.4.Problems arise in the implementation of strategies since it is concluded that no current EC or UK national legislation addresses the problem of freshwater eutrophication in a comprehensive manner.5.Forthcoming Statutory Water Quality Objectives may be instrumental in providing the legal means by which such reductions could be achieved, if the importance of diffuse sources from agriculture is acknowl

ISSN:1052-7613    

DOI:10.1002/aqc.3270030308

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

摘要:

Abstract1.Temporary waters have been relatively neglected in British nature conservation, due in part to paucity of survey and comparative assessment. Such water bodies hold distinctive and specialized biological communities, and the need for conservation measures at key localities is increasingly recognized in Europe.2.An account of the vegetation and invertebrate fauna in Pant‐y‐llyn, a small temporary lake on Carboniferous Limestone in South Wales, is presented. Water levels in the basin reflect seasonal variation in the height of the local groundwater, and it fills to a depth ofca3–4 m in winter but is almost completely dry in summer.3.There is a clearly displayed sequence of bryophyte, herbaceous swamp and woody plant communities which occupy different depth zones in the basin.4.The invertebrate community is dominated by microcrustaceans and a range of insect groups; adaptations for survival over the summer dry phase are considered.5.It is concluded that the ecological characteristics and distinctive hydrological features of Pant‐y‐llyn closely resemble those of the Irish turloughs. Pant‐y‐llyn thus represents an important site for conservation as the only known example of this form of seasonal water bo

ISSN:1052-7613    

DOI:10.1002/aqc.3270030309

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

摘要:

Abstract1.The establishment of Marine Protected Areas in the UK has been an extremely slow process. Two sites have statutory protection and a further nine are voluntary marine conservation areas.2.There has been a distinctly different approach to site protection depending on whether the initiative is statutory or voluntary. The advantages and disadvantages of each are illustrated through examples.3.Sites with voluntary protection are often seen as positive, and involving the local community. The overriding issue for legally protected sites is concern that they are a threat to existing rights.4.A combined approach is needed. There should be statutory protection for key sites, whereas voluntary marine protected areas should be encouraged all around the coast, regardless of whether an area is of nature conservation value.5.A key lesson to learn from the voluntary approach is the need to involve people who will be affected by the proposals as early as possible.

ISSN:1052-7613    

DOI:10.1002/aqc.3270030310

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

ISSN:1052-7613    

DOI:10.1002/aqc.3270030311

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

ISSN:1052-7613    

DOI:10.1002/aqc.3270030313

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY