首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 31 毫秒
1.
  • 1. A detailed study on the spatial and temporal patterns of reef fish assemblages associated with non‐reefal coral communities at A Ma Wan (AMW) and A Ye Wan (AYW) in Tung Ping Chau, Hong Kong, China, was carried out using an underwater visual census method from January 1998 to December 1999.
  • 2. The study identified a total of 106 species (76 genera in 39 families) of fish in the study sites, in which 88 species were recorded in AMW and 78 species in AYW. Seasonal patterns in the abundance and species richness of all reef fishes and most of the frequently encountered families/trophic groups in both study sites were observed. Seasonal fluctuation of macroalgae, the influence of recruitment of larvae, and the possible seasonal variation in the behaviour of fish may all contribute to these observed seasonal patterns.
  • 3. Multidimensional scaling (MDS) ordinations demonstrated that there were spatial variations in the fish community structures within and between sites. Such spatial patterns were possibly related to the spatial variation of the coral community structures in the study sites. The ordinations also showed that the fish community structures in the study sites were not seasonally stable. Such temporal instability of the fish community structures may be partly due to habitat isolation among the fish communities around the island.
  • 4. These results imply that preservation and enhancement of habitat connectivity of the coral communities should be one of the main conservation strategies for the reef fish communities of Tung Ping Chau, and those of Hong Kong in general. This strategy may be equally applicable to other non‐reefal coral communities elsewhere around the world.
Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   

2.
3.
4.
  • 1. Hardbottom habitats of Biscayne Bay, a shallow lagoon adjacent to the city of Miami, Florida, USA, contain a limited number of coral species that represent a small subset of the species found at nearby offshore hardbottom and reef habitats of the Florida Reef Tract. Although the physical characteristics of this basin make it a marginal environment for coral growth, the presence of dense populations of Siderastrea radians and Porites furcata indicate that these, as well as other corals that are found at lower densities, are able to tolerate extreme and fluctuating conditions. Three factors, temperature, sedimentation, and salinity, appear to limit coral abundance, diversity, and distribution within Biscayne Bay.
  • 2. Temperatures exhibit high frequencies of extreme high and low values known to cause coral stress and mortality elsewhere. Similarly, sedimentation rates are very high and sediment resuspension caused by currents, storms and boating activities commonly bury corals under sediment layers. Sediment burial was shown experimentally to influence growth and mortality of S. radians.
  • 3. The salinity of Biscayne Bay is influenced by freshwater inputs from canal, sheetflow and groundwater sources that create a near‐shore environment with low mean salinity and high salinity fluctuation. Coral communities along this western margin have the lowest coral density and species richness. Chronic exposure to low salinity was shown experimentally to cause a decrease in the growth of S. radians.
  • 4. The location of Biscayne Bay, downstream of a large restoration effort planned for the Everglades watershed, highlights the need to understand the relationship between the physical environment and the health of benthic communities. The data presented here provide the type of scientific information needed so that management decisions can take into account the potential impacts of human activities on the health of coral populations that are already near their tolerance limits for temperature, salinity, and sedimentation.
Copyright © 2003 John Wiley & Sons, Ltd.  相似文献   

5.
  • 1. Coral reefs around the world have been deteriorating over decades owing to anthropogenic pressure. In the Caribbean recent rates of decline are alarming, particularly for coral reefs under high local human impact, many of which are severely degraded, although regions with lower direct anthropogenic influence seem less affected.
  • 2. Little Cayman is a relatively undeveloped island, with less than 150 permanent residents. About 20% of its reefs have been protected by no‐take marine reserves since the mid‐1980s. We analysed the dynamics of coral communities around the island from 1999 to 2004 in order to test the hypothesis that a lack of major local anthropogenic disturbances is enough to prevent decline of coral populations.
  • 3. Live hard coral coverage, coral diversity, abundance, mortality, size, and prevalence of disease and bleaching were measured using the Atlantic and Gulf Rapid Reef Assessment methodology (line transects) at nine sites. Despite the apparent undisturbed condition of the island, a 40% relative reduction of mean live coral coverage (from 26% to 16%, absolute change was 10%) was recorded in five years. Mean mortality varied from year to year from 23% to 27%. Overall mean diameter and height have decreased between 6% and 15% on average (from 47 to 40 cm for diameter, and from 31 to 29 cm for height).
  • 4. The relative abundance of large reef builders of the genus Montastraea decreased, while that of smaller corals of the genera Agaricia and Porites increased. Disease prevalence has increased over time, and at least one relatively large bleaching event (affecting 10% of the corals) took place in 2003.
  • 5. Mean live coral cover decline was similar inside (from 29% to 19%) and outside (from 24% to 14%) marine no‐take reserves. No significant difference in disease prevalence or clear pattern in bleaching frequency was observed between protected and non‐protected areas. It is concluded that more comprehensive management strategies are needed in order to effectively protect coral communities from degradation.
Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

6.
  • 1. Forest restoration through silviculture (gardening) programs revives productivity, biodiversity, and stability. As in silviculture approaches, the coral ‘gardening’ strategy is based on a two‐step protocol.
  • 2. The first step deals with the establishment of in situ and/or ex situ coral nurseries in which corals are farmed (originating from two types of source material: asexual [ramets, nubbins], and sexual [planula larvae, spat] recruits).
  • 3. The second is the reef rehabilitation step, where maricultured colonies are transplanted into degraded sites.
  • 4. We compare here the rationale of forest restoration to coral reef ecosystem restoration by evaluating major key criteria. As in silviculture programs, a sustainable mariculture operation that focuses on the prime structural component of the reef (‘gardening’ with corals) may promote the persistence of threatened coral populations, as well as that of other reef taxa, thus maintaining genetic diversity. In chronically degrading reef sites this may facilitate a halt in biodiversity depletion.
  • 5. Within the current theoretical framework of ecosystem restoration, the recovery of biodiversity indices is considered a core element since a rich species diversity provides higher ecosystem resilience to disturbances.
  • 6. The gardening measure may also be implemented worldwide, eliminating the need to extract existing colonies for transplantation operations. At degraded reef sites, the coral gardening strategy can assist in managing human and non‐human stakeholders' requirements as is done in forest management.
Copyright © 2003 John Wiley & Sons, Ltd.  相似文献   

7.
8.
9.
  1. Coral reef biodiversity is rapidly decreasing as a result of the loss of coral cover, which modifies the structure and functioning of the ecosystem. Understanding how coral reef communities respond in space and over the long term is essential in order to implement management strategies and reduce the effects of biodiversity loss on coral reefs.
  2. Fish, coral, and algae communities were used as indicators to evaluate changes in coral reef systems. The variation of these communities was studied in a marine protected area composed of three management zones in Cozumel Coral Reef National Park in Quintana Roo, Mexico, over a period of 11 years (2004–2014). The following parameters were monitored annually: (i) total fish density; (ii) fish trophic group densities; (iii) species richness and three fish diversity indices; (iv) relative scleractinian coral cover; and (v) relative macroalgae cover.
  3. In the years in which coastal development, such as the construction of a marina, took place, an increase in the abundance of territorial herbivorous and planktivorous fish was observed. As the coral recovered, macrocarnivores and sessile benthic invertivores were re‐established, whereas scraper herbivores showed no changes in the period of study in any of the three management zones.
  4. Coral cover recovery showed rapid phase‐shift reversal (phase‐shift, macroalgae dominance over coral) in the three zones. Even though the fish density and coral cover recovered, the diversity indices of each fish trophic group exhibited a reduction in the three management zones over time.
  相似文献   

10.
11.
12.
13.
  1. Tetraodontiformes fishes play a critical role in benthic and demersal communities and are facing threats due to anthropogenic impacts and climate change. However, they are poorly studied worldwide. To improve knowledge on the socio‐ecological significance and conservation of Tetraodontiformes a review of literature addressing the diversity, ecology, use and trade, conservation, and main threats of Tetraodontiformes combined with a comprehensive in situ dataset from two broad‐range multidisciplinary oceanographic surveys performed along the Tropical Brazilian Continental Shelf was undertaken.
  2. Twenty‐nine species were identified, being primarily found on coral reefs and algal ecosystems. At these habitats, tetraodontids present highly diversified trophic categories and might play an important role by balancing the marine food web
  3. Coral reef ecosystems, especially those near to the shelf break, seem to be the most important areas of Tetraodontiformes fishes, concentrating the highest values of species richness, relative abundance and the uncommon and Near Threatened species.
  4. Ninety per cent of species are commonly caught as bycatch, being also used in the ornamental trade (69%) and as food (52%), serving as an important source of income for artisanal local fisheries.
  5. Tetraodontiformes are threatened by unregulated fisheries, overexploitation, bycatch, and habitat loss due to coral reef degradation and the potential effects of climate change. These factors are more broadly impacting global biodiversity, food security, and other related ecosystem functions upon which humans and many other organisms rely.
  6. We recommend the following steps that could improve the conservation of Tetraodontiformes along the tropical Brazilian Continental shelf and elsewhere: (i) data collection of the commercial, incidental, ornamental and recreational catches; (ii) improvement of the current legislation directed at the marine ornamental harvesting; (iii) increase efforts focused on the education and conservation awareness in coastal tourism and communities; and, most important, (iv) creation of marine reserves networks in priority areas of conservation, protecting either the species and key habitats for its survival.
  相似文献   

14.
  • 1. In order to promote the establishment of the first marine protected area (MPA) in Taiwan, the conservation values of 12 reef sites in the Penghu Islands were evaluated. The results together with a 6‐year surveillance programme revealed that the Chinwan Inner Bay (CIB) possesses the best coral community in the Penghu Islands with the highest coral cover, high species diversity and habitat types, as well as a high conservation value.
  • 2. Utilization of biological resources and socio‐economic factors of CIB were investigated by intensive field surveys and a complete visit‐and‐poll survey respectively. Most of the fishing at CIB is for recreational purposes and is characterized by low investment, low harvest rates, high dependence on weather conditions, and self‐consumption.
  • 3. The socio‐economic data showed that there was basically no direct conflict of interests with local communities at two neighbouring villages, and most local residents indicated that they would support the MPA proposal.
  • 4. A blueprint for a CIB MPA based on the results of these biological and socio‐economic investigations is proposed. Environmental threats including anchor damage and the predation of Drupella snails need to be ameliorated and monitored through the implementation of appropriate management. The involvement of local communities is key to the success of this MPA and environmental education is recommended to promote public awareness.
Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

15.
  • 1. To monitor any impacts to coral reefs related to the exponential growth of tourism in the South Sinai region of the Egyptian Red Sea, nine stations were established at key reef sites over 2002–2003. At each station coral cover was determined using a video survey method at depths of 3, 7 and 16 m, and fish abundance by underwater visual census at depths of 3 and 10 m.
  • 2. Mean total coral cover (hard plus soft) ranged from 58% to 23% at 3 m, 50% to 14% at 7 m, and 52% to 13% at 16 m, and hard coral cover from 37.5% to 15.7% at 3 m, 32.8% to 7.0% at 7 m, and 17.8% to 2.2% at 16 m. Analyses confirmed differences in coral assemblage related to depth and wave exposure.
  • 3. Fish abundances and assemblages also varied with depth and proximity of deep water. Also the one site subject to fishing had lower abundances of some commercial fish families and greater abundances of some herbivores.
  • 4. Transects subject to greater tourist use did not segregate from those subject to less tourist use, despite evidence from other work of an effect from visitor damage to corals at some sites. This may be because visitors were more attracted to sites that had higher coral cover.
  • 5. Comparison of the present data with that from past studies is difficult because of the differences in sites and method employed, but several observations suggest a moderate decline in coral cover during recent decades. Such a decline would be compatible with the recorded impact of an outbreak of crown‐of‐thorns starfish, Acanthaster planci, as well as with other evidence of accumulating damage by visitors.
  • 6. Further monitoring using the same stations and consistent protocols is urgently required.
Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   

16.
17.
18.
19.
  • 1. Surveys of coral reefs in northern Tanzania were conducted in 2004/5 with the aim of comparing them over an~8‐year period during a time of increased efforts at fisheries management and the 1998 El Niño Southern Oscillation (ENSO) and Indian Ocean Dipole (IOD) coral mortality event that caused 45% mortality in northern Tanzania and much of the Indian Ocean.
  • 2. Changes associated with both management, its absence, and the ENSO were found but changes were generally small and ecological measures indicated stability or improvements over this period, particularly when compared with reports from much of the northern Indian Ocean.
  • 3. Fisheries management in two areas increased the biomass of fish and benthic communities. A small fisheries closure (0.3 km2) displayed little change in the coral community but ecological conditions declined as measured by sea urchins and fish abundances. This change may be associated with its small size because similar changes were not measured in the large closure (28 km2).
  • 4. The few sites without any increased management were still degraded and one site had experienced a population explosion of a pest sea urchin, Echinometra mathaei.
  • 5. The lack of significant changes across this disturbance indicates that these reefs are moderately resilient to climate change and, therefore, a high priority for future conservation actions.
Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

20.
  1. Gorgonians dwelling on the Mediterranean continental shelf are among the most frequent fishing bycatch taxa. These species display several traits, such as long lifespans and slow growth, which make them very vulnerable to the impacts caused by fishing activities with far‐reaching and long‐lasting effects.
  2. Hence, restoration and mitigation actions are crucial to enhance and speed up the natural recovery of damaged cold‐water coral gardens. Given the growing concern to develop effective and affordable restoration actions, the present study aims to propose and technically validate a new large‐scale and cost‐effective restoration method.
  3. This technique, named ‘badminton method', consists of attaching bycatch Eunicella cavolini colonies to cobble supports and returning them to the continental shelf by gently throwing the gorgonian transplants directly from a boat.
  4. Two consecutive field experiments were conducted in order to find the best cobble type support and gorgonian size to be used: first, to evaluate the landing efficiency of gorgonian transplants at different depths (from 5 to 30 m) and second, to evaluate their capability to maintain a correct position over time.
  5. Natural cobbles with large gorgonians attached were the best option. Field results and modelling approaches suggest that the transplants would correctly land on the continental shelf seabed in a predicted area of around 60 m2. Moreover, they would successfully maintain an upright position ensuring gorgonian survival over time.
  6. The success of this method highlights the feasibility of large‐scale and low‐cost restoration actions with promising results for the conservation and recovery of cold‐water coral gardens.
  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号