大神堂人工鱼礁礁区布局的合理性研究(英文)

以CFD(计算流体动力学)技术为手段,研究了不同配置组合人工鱼礁区周围的流场效应。研究中采用了四种配置组合,分别为"444"三列,"464"三列,"12345"五列三角形,"34543"五列正六边形进行数值模拟,结果说明大神堂人工鱼礁礁区的礁群配置组合能够较好地发挥礁区的调控作用。     

Measuring good governance for complex ecosystems: Perceptions of coral reef-dependent communities in the Caribbean

Good governance is widely seen as a prerequisite for effective natural resources management in the context of environmental decline and increasing anthropogenic pressures. Few studies quantitatively examine governance principles, or explore links between perceptions of community members and the governance that shapes their behaviour. Comparative work, spanning multiple sites and contexts, is rare. This paper measures community members’ perceptions of governance in twelve coral reef-dependent communities across four countries in the Wider Caribbean Region. In relation to established principles of ‘good governance’, multiple correspondence analysis indicates that perceptions can be reliably described using two themes, institutional acceptance and engagement. These explain over 50% of variation in individual perceptions. These measurable themes provide an indication of the social fit of governance arrangements, and have implications for expected outcomes, including support for management and compliance with regulations. Cluster analysis provides unique empirical evidence linking structural characteristics of governance to community perceptions; four of five good governance indicators were present in communities with positive perceptions. Results suggest a combination of supportive structures and processes are necessary to achieve governance systems positively perceived by community members. Findings are relevant to those seeking to design management systems and governance structures that are appropriate to local circumstances and will engender stakeholder support.     

Lethal doses of oxbile,peptones and thiosulfate-citrate-bile-sucrose agar (TCBS) for Acanthaster planci; exploring alternative population control options

Effective control of outbreaks of Acanthaster planci represents the most immediate and practical intervention to reverse sustained declines in coral cover on reefs in the Indo-Pacific. This study explored the minimum doses of oxbile, oxgall, and thiosulfate-citrate-bile-sucrose agar (TCBS) that result in reliable and comprehensive mortality when injected into adult A. planci. The minimum doses required to induce 100% mortality among starfish (n = 10) were 4 g l⁻¹ of oxbile, 8 g l⁻¹ of oxgall and 22 g l⁻¹ of TCBS. Moreover, there was no evidence of unintended side effects for other coral reef organisms (e.g., scleractinian corals, echinoderms and fishes) when using oxbile, oxgall, or TCBS at minimum doses. The effectiveness of peptones in killing crown-of-thorns starfish was also tested, but inconsistency in the results revealed that these proteins are unreliable.     

Field observations of wave refraction and propagation pathways on coral reef platforms

Field experiments were conducted to investigate the refraction and propagation of ocean waves across two coral reef platforms in the Maldives, central Indian Ocean. A total of seven pressure sensors were deployed on each reef to quantify temporal and spatial variations in wave characteristics across the platform surfaces. Directional wave properties were calculated from high frequency (2 Hz) wave and current records obtained at two locations on each reef and corroborate theoretically predicted propagation pathways derived from an analytical wave refraction model. Results demonstrate that reef geometry critically controls the refraction and propagation behaviour of incident swell across the reef structures. Differences in the magnitude of refraction (approximately 57° and 14°) observed on each reef can be attributed to variations in platform shape and orientation to incident waves. Results demonstrate that reef flat wave patterns define the segmentation of platform surfaces into distinctive high and low wave energy zones. Furthermore, wave focussing has been identified as a major mechanism controlling the transformation of wave energy across the reefs. Results provide the first field‐based validation of wave refraction and convergence on coral reefs and have significant implications for sedimentation processes and the formation of platform deposits. Reef configurations which promote marked wave convergence are more likely to retain sediment on the reef surface, whereas platforms that induce less refraction and changes in the direction of incident waves have a higher potential for the off‐reef evacuation of sediment over leeward reef margins. Results of wave measurements substantiate such projections and provide a first order explanation for the existence and absence of a coral cay on the two study reefs. The study presents empirical evidence of wave refraction and convergence on coral reefs and establishes a baseline for future investigations of hydrodynamic process controls on platform sedimentation and island formation. Copyright © 2012 John Wiley & Sons, Ltd.     

Link between sewage-derived nitrogen pollution and coral disease severity in Guam

The goals of this study were to evaluate the contribution of sewage-derived N to reef flat communities in Guam and to assess the impact of N inputs on coral disease. We used stable isotope analysis of macroalgae and a soft coral, sampled bimonthly, as a proxy for N dynamics, and surveyed Porites spp., a dominant coral taxon on Guam’s reefs, for white syndrome disease severity. Results showed a strong influence of sewage-derived N in nearshore waters, with δ¹⁵N values varying as a function of species sampled, site, and sampling date. Increases in sewage-derived N correlated significantly with increases in the severity of disease among Porites spp., with δ¹⁵N values accounting for more than 48% of the variation in changes in disease severity. The anticipated military realignment and related population increase in Guam are expected to lead to increased white syndrome infections and other coral diseases.     

Macroalgae in the coral reefs of Eilat (Gulf of Aqaba, Red Sea) as a possible indicator of reef degradation

The current state of health of the coral reefs in the northern Gulf of Aqaba (Red Sea), notably the Eilat reefs, is under debate regarding both their exact condition and the causes of degradation. A dearth of earlier data and unequivocal reliable indices are the major problems hinder a clear understanding of the reef state. Our research objective was to examine coral-algal dynamics as a potential cause and an indication of reef degradation. The community structure of stony corals and algae along the northern Gulf of Aqaba reveal non-seasonal turf algae dominancy in the shallow Eilat reefs (up to 72%), while the proximate Aqaba reefs present negligible turf cover (<6%). We believe that turf dominancy can indicate degradation in these reefs, based on the reduction in essential reef components followed by proliferation of perennial turf algae. Our findings provide further evidence for the severe state of the Eilat coral reefs.     

Coral Ba/Ca records of sediment input to the fringing reef of the southshore of Moloka’i, Hawai’i over the last several decades

The fringing reef of southern Moloka’i is perceived to be in decline because of land-based pollution. In the absence of historical records of sediment pollution, ratios of coral Ba/Ca were used to test the hypothesis that sedimentation has increased over time. Baseline Ba/Ca ratios co-vary with the abundance of red, terrigenous sediment visible in recent imagery. The highest values at One Ali’i are near one of the muddiest parts of the reef. This co-varies with the lowest growth rate of all the sites, perhaps because the upstream Kawela watershed was historically leveed all the way to the nearshore, providing a fast-path for sediment delivery. Sites adjacent to small, steep watersheds have ∼decadal periodicities whereas sites adjacent to mangrove forests have shorter-period fluctuations that correspond to the periodicity of sediment transport in the nearshore, rather than the watershed. All four sites show a statistically significant upward trend in Ba/Ca.     

Geomorphic evidence of major sea-level fluctuations during marine isotope substage-5e, Cape Cuvier, Western Australia

A detailed geomorphologic and morphostratigraphic investigation of raised marine terraces at Cape Cuvier, Western Australia, reveals two morphologically distinct units. A lower, well-developed accretional reef terrace between 3 and 5.5 m above MLWS (mean low-water springs; hereafter denoted as “+”) represents an extended interval of stable sea level. An upper erosional terrace and incipient coralgal rim between + 8.5 to 10.5 m represents a brief sea-level stillstand at this higher elevation. These features suggest the lower and upper terraces developed during discrete sea-level events. In an attempt to better define the timing of emplacement of each marine unit, 20 coral samples collected along vertical and lateral reef growth axis from both terraces were analysed with U-series dating. Unfortunately, all coral samples exhibited elevated δ²³⁴U_initial values, suggesting that pervasive uptake of ²³⁴U-enriched uranium and ²³⁰Th thorium had occurred. Despite the shortcomings of absolute dating, a succession of events can be resolved though morphostratigraphic relationships. Comparison of the facies relationships, coral growth, and morphostratigraphic features between the lower and upper terraces indicates that an early to mid MIS 5e stillstand at + 3 to 5 m was followed by a late rise to + 8.5 to 10.5 m. This agrees with an emerging global view of MIS 5e sea-level history derived from stable carbonate platforms, rejecting the hypothesis that these higher sea-level benchmarks are an artefact of localized tectonic processes.     

Tropical species at the northern limit of their range: Composition and distribution in Bermuda's benthic habitats in relation to depth and light availability

Surveys were undertaken on the shallow Bermuda marine platform between 2006 and 2008 to provide a baseline of the distribution, condition and environmental characteristics of benthic communities. Bermuda is located in temperate latitudes but coral reefs, tropical seagrasses and calcareous green algae are common in the shallow waters of the platform. The dominant organisms of these communities are all living at or near their northern latitudinal range limits in the Atlantic Ocean. Among the major benthic autotrophs surveyed, seagrasses were most restricted by light availability. We found that the relatively slow-growing and long-lived seagrass Thalassia testudinum is restricted to habitats with much higher light availability than in the tropical locations where this species is commonly found. In contrast, the faster growing tropical seagrasses in Bermuda, Syringodium filiforme, Halodule sp. and Halophila decipiens, had similar ecological compensation depths (ECD) as in tropical locations. Increasing sea surface temperatures, concomitant with global climate change, may either drive or allow the poleward extensions of the ranges of such tropical species. However, due to latitudinal light limitations at least one abundant and common tropical autotroph, T. testudinum, is able to occupy only shallower depths at the more temperate latitudes of Bermuda. We hypothesize that the poleward shift of seagrass species ranges would be accompanied by restrictions to even shallower depths of T. testudinum and by very different seagrass community structures than in tropical locations.     

Health of the coral reefs at the US Navy Base,Guantánamo Bay,Cuba: A preliminary report based on isotopic records from gorgonians

Specimens of the gorgonian Plexaura homomalla were sampled from several areas along the fringing reefs fronting the United States Naval Base at Guantánamo Bay, Cuba. Sample coverage extended from apparently healthy reefs in oceanic waters to declining reefs located in the plume of the drainage from upper parts of Guantánamo Bay. Tentacle tips were excised, and trunk sections were cut and polished. Stable isotope ratios of nitrogen (δ¹⁵N) and carbon indicate a strong correlation of reef health with proximity to the plume of the river.