Marine reserves,fisheries ban,and 20 years of positive change in a coral reef ecosystem

By 2004, Belize was exhibiting classic fishing down of the food web. Groupers (Serranidae) and snappers (Lutjanidae) were scarce and fisheries turned to parrotfishes (Scarinae), leading to a 41% decline in their biomass. Several policies were enacted in 2009–2010, including a moratorium on fishing parrotfish and a new marine park with no-take areas. Using a 20-year time series on reef fish and benthos, we evaluated the impact of these policies approximately 10 years after their implementation. Establishment of the Southwater Caye Marine Reserve led to a recovery of snapper at 2 out of 3 sites, but there was no evidence of recovery outside the reserve. Snapper populations in an older reserve continued to increase, implying that at least 9 years is required for their recovery. Despite concerns over the feasibility of banning parrotfish harvest once it has become a dominant fin fishery, parrotfishes returned and exceeded biomass levels prior to the fishery. The majority of these changes involved an increase in parrotfish density; species composition and adult body size generally exhibited little change. Recovery occurred equally well in reserves and areas open to other forms of fishing, implying strong compliance. Temporal trends in parrotfish grazing intensity were strongly negatively associated with the cover of macroalgae, which by 2018 had fallen to the lowest levels observed since measurements began in 1998. Coral populations remained resilient and continued to exhibit periods of net recovery after disturbance. We found that a moratorium on parrotfish harvesting is feasible and appears to help constrain macroalgae, which can otherwise impede coral resilience.     

Coastal zone management in Wales: The information gaps

In 1994 the Countryside Council for Wales, the government nature conservation and countryside advisor in Wales, published a consultation document on marine and coastal policy, and also commissioned research into the status of coastal zone management (CZM) in the Principality. The research, undertaken by the University of Wales Cardiff, investigated CZM from an international, national (U.K.) and Welsh perspective, concentrating on detailed case studies of three areas (including both urban and rural coasts). Policy makers, managers, practitioners and users from all sectors were included in the study which established current activity, identified problems and reviewe future plans. Interviews and questionnaire returns highlighted vital information gaps at all levels. These ranged fom a lack of basic data (including scientific and technical), to a breakdown in communication both within and between organisations, as well as a policy vacuum in both regional and central government.     

The Irish Sea: towards a more effective science strategy

The Irish Sea’s distinctive hydrographic features present unique opportunities for research into the complex processes that regulate shelf-sea ecosystems. Such studies are essential in developing capabilities to detect and evaluate change in marine environments. A 1993 review showed almost 230 projects underway on the Irish Sea, spanning all the major fields of marine science. But a large proportion of research projects failed to indicate the purpose of the work; overall, there was a remarkable absence of clarity and specificity in the objectives. Progress in some fields is also hampered by insufficient coordination and cohesion; at present there are no standing arrangements between Ireland and the United Kingdom that provide for bilateral co-ordination of scientific work in the area. There is clearly a need for a more planned and integrated Irish Sea science programme to provide information for management purposes and also to advance scientific understanding of the components and functions of Irish Sea ecosystems, and how and why they change with time. There is a common belief that the first of these predominantly involves monitoring, and the second research. However, the paper cautions that this is a dubious and unnecessary distinction. A strategy aimed at better integration of research and monitoring (e.g. a framework of linked objectives and targets) could substantially increase the information dividend from current investments in Irish Sea science. Based on a joint Irish/UK review, this paper outlines studies and approaches that are seen as key elements of a future, more relevant and cost-effective research programme for the Irish Sea.     

The suitability of gastropods as biomarkers

The measurement and induction of mixed function oxyigenases (MFOs) of limnetic gastropods were investigated to estimate their suitability as biomarkers. A determination of MFO activities was performed through the measurement of ethoxyresorufin-O-dealkylase (EROD), pentoxy-(PROD) and benzoxyresorufin-O-dealkylase-activity (BROD). Optimal measuring conditions of these activities were investigated in preparations of the digestive gland of 4 species of limnetic gastropods. Results indicate that MFO-activity inhibiting substances are accumulating in the microsomal pellet, the fraction commonly used for the measurement of MFO-activities. Therefore, the fraction used for induction studies was the postmitochondrial supernatant (PMS). EROD, PROD, and BROD activity ofPlanorbis planorbis andPlanorbis carinatus were measured after a treatment with Aroclor 1254 for 1–17 days. Maximal induction of EROD and PROD were 6 and 10 times the value in the control group ofP. carinatus, respectively induction inP. planorbis was lower. BROD-activity could not been measured inP. planorbis. InP. carinatus, BROD-activity increased to a maximum of 2 times after traetment with Aroclor 1254. The level of induction of EROD-activity is comparable to results described in analog studies with fish.     

Contaminants and their effects on estuarine and coastal organisms in the United Kingdom in the late twentieth century

The biological effects of contaminants in British estuaries and coastal waters have been studied for over 100 years. Until the 1970s. the major pollution impact on estuarine organisms was probably caused by poorly treated sewage which led to severe oxygen deficits and consequent asphyxiation of many water-breathers. However, since the introduction of improved sewage treatment in the last 30 years, a number of continuing impacts have come to light which represent true toxic effects of micro-contaminants. Sublethal changes observed in various bioassays and biomarkers are widespread in both fish and invertebrates, and in the most urbanised and industrialised estuaries, these effects are probably having impacts at the population and community levels. For example, there is good evidence to show that tributyltin from some antifouling paints has not only affected the sexuality and reproductive success of individual estuarine and coastal molluscs, but has also damaged some benthic communities of which molluscs are but a part. Although there are data to show that some contaminant concentrations are now declining, we do not yet have enough data in most cases to decide whether organisms have also begun to recover. This paper reviews the entire field of contaminant effects in UK estuarine and marine waters, focusing especially on the years 1985-2000, and makes some recommendations for future research and monitoring programmes.     

Does the presence of non-breeders enhance the fitness of breeders? An experimental analysis in the clown anemonefish<Emphasis Type="Italic"> Amphiprion percula</Emphasis>

The stability of animal societies depends on individuals decisions about whether to tolerate or evict others and about whether to stay or leave. These decisions, in turn, depend on individuals costs and benefits of living in the group. The clown anemonefish, Amphiprion percula, lives in groups composed of a breeding pair and zero to four non-breeders. To determine why breeders accept the presence of non-breeders in this species I investigated the effect of non-breeders on multiple components of the breeders fitness. Non-breeders did not assist breeders in any obvious way. Experimental removal of non-breeders had no significant effect on the survival, growth, or reproductive success of breeders. Experimental removal of one of the breeding pair showed that non-breeders had little effect on the time taken for a widowed breeder to recommence breeding. The results indicate that the presence of non-breeders neither enhances, nor reduces, the fitness of breeders in A. percula. I suggest that non-breeders might modulate their effect on the fitness of breeders, either by reducing the costs they inflict or by increasing the benefits they provide, such that it just pays breeders to tolerate, rather than to evict, them. This study illustrates that animal societies can be stable even when some individuals gain nothing from the association.Communicated by M. Abrahams     

中国海岸侵蚀危害及其防治

防治海岸侵蚀是减灾防灾的一项重要内容．本文从海岸侵蚀的产生机理出发，针对其造成危害的侵蚀分布特点加以论述，并给出了应采取的整治对策．     

Marine shrimp aquaculture and natural resource degradation in Thailand

Rising demand for shrimp in the developed nations has helped to foster a dramatic growth in marine shrimp aquaculture, particularly in South America and South Asia. In Thailand, Marine shrimp aquaculture is now an important earmer of foreign exchange. The growth in Production has been achieved through the expansion of the culture area and the adoption of intensive production methods. The conversion of near-shore areas to shrimp culture, however, is proving to have many consequences that impinge on the environmental integrity of coastal areas. This paper reviews the development of Thailand's marine shrimp culture industry and examines the nature of the environmental impacts that are emerging. It then discusses the implications these have for rural poor and the long-term viability of the culture industry.     

Effects of drilling fluids on marine bacteria from a Nigerian offshore oilfield

Two marine bacterial isolates from drill mud cuttings obtained from Agbara oilfield,Staphylococcus sp. andBacillus sp., were cultured aerobically in the presence of varying concentrations (0, 25, 50, and 75 μg/ml) of drilling fluids to determine the effects of concentration of toxicants on their growth. With the exception of Clairsol, Enviromul, and Baroid mineral oil, which had little or no effect, the exponential growth ofBacillus sp. was depressed by all other test chemicals. Additionally, all test chemicals except Clairsol had no effect on lag phase of growth ofBacillus sp. WithStaphylococcus sp. the depressive effect on the exponential phase of growth was shown by almost all test chemicals. There was enhancement of both growth rate and generation times ofStaphylococcus sp. and decrease of those ofBacillus sp. with increasing concentrations of drilling fluids. These results show that while some drilling fluids may be stimulatory or depressive to bacterial growth, others may be without effect.     

Heavy metals in top core sediments from the southern Campania shelf (Italy): Hints to define large-scale geochemical backgrounds

The results of a geochemical survey carried out on the southern Campania shelf (southern Italy) are illustrated, offering a tempting opportunity to discuss the statement and definition of regional geochemical backgrounds for selected heavy metals. A total of 104 top core sediments, collected on average 1.5 km from one another and covering a shelf area of about 1300 km², were analysed for grain size, organic carbon content (OC), and heavy-metal (As, Al, Fe, Cd, V, Cr, Zn, Cu, Ni, Hg, and Pb) concentrations. The characteristics of the area, scarcely influenced by industrial activities, and the extensive data set, make this study suitable for an appropriate multivariate and spatial geostatistical methodologies used for i) a reliable definition of large-scale marine sediments' geochemical backgrounds and ii) an accurate discrimination of different geological controls on trace-element distribution patterns. Enrichment factors estimated with respect to both the average shale composition and the weighted average metal concentrations measured in inland soils rule out significant anthropogenic inputs. A spatial-geostatistics approach (kriging of spatial component based on an accurate implementation of variographic surveying) was applied, and this is proposed as an appropriate quantitative methodology to define the geochemical backgrounds for the different heavy metals. Two nested spatial structures were identified for some of the heavy metals, thus allowing clear identification of local and regional geochemical controls related to the different spatial variability of grain size.