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Maria Vanessa Baria‐Rodriguez Dexter W. dela Cruz Romeo M. Dizon Helen T. Yap Ronald D. Villanueva 《水产资源保护:海洋与淡水生态系统》2019,29(6):891-900
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Sarit Lampert‐Karako Noga Stambler Don J. Katcoff Yair Achituv Zvy Dubinsky Noa Simon‐Blecher 《水产资源保护:海洋与淡水生态系统》2008,18(6):1039-1045
- 1. The symbiotic association between corals and zooxanthellae has been a major contributing factor in the success of reef‐building corals.
- 2. The diversity of zooxanthellae harboured in the hermatypic coral Stylophora pistillata in the Gulf of Eilat (Aqaba), northern Red Sea, was investigated on the basis of the length and sequence variation of the 18S small subunit ribosomal DNA. Of several clades found worldwide, only clades A and C were found to be associated with this coral species in the Gulf.
- 3. No correlation between the pink and brown colour morphs of the coral S. pistillata and the zooxanthella clade was found. Shallow‐water colonies (5 m) harbour clade A while deeper‐water colonies (17 m) harbour either clade A or C. This coral is a brooding species that associates with different zooxanthellae at different depths.
- 4. Eutrophication from fish farms did not affect clade identity associated with Stylophora.
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Jean‐Baptiste Ledoux Silvia Frias‐Vidal Ignasi Montero‐Serra Agostinho Antunes Clara Casado Bueno Sergi Civit Paula Lopez‐Sendino Cristina Linares Joaquim Garrabou 《水产资源保护:海洋与淡水生态系统》2020,30(6):1149-1159
- Understanding the interactions among demographic parameters, mating system and population dynamics is key to predict the response of populations to global change. The Mediterranean red coral is a precious octocoral suffering from population decline due to overfishing and warming‐driven mass mortality events.
- While the demographic consequences of these two pressures are well characterized, little is known regarding their impact on population dynamics and evolution of red coral populations. The main objective of this study was to fill this gap focusing more particularly on mating pattern and genetic drift.
- Combining sibship and progeny arrays analyses, a genetic characterization of the red coral mating system was conducted. In addition, a synchronic approach was developed comparing mating patterns in two populations with contrasting demographic patterns: a pristine‐like population and a declining population.
- The results show that polyandry is likely to be the norm in red coral. The similar patterns of genetic diversity between adults and larvae combined with the lack of differential reproductive success among putative fathers did not support significant sweepstakes effects during larval production. While instantaneous biparental inbreeding was detected, no long‐term inbreeding was observed even in the declining population. Mating patterns and effective population sizes in the two populations were not statistically different. Nevertheless, a trend towards a slightly higher inbreeding and a lower number of breeders was observed in the declining population.
- Accordingly, we hypothesized that an increase in male gamete dispersal may buffer the increase of genetic drift expected in the declining population. This feedback between demographic decline and reproductive pattern may potentially take part in the long‐term persistence of red coral populations. However, the negative trend reported in the declining population unambiguously supports the need to maintain high densities of reproductive colonies to the functioning of red coral populations.
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- 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.
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Jhann Garar Þorbjrnsson Jnína Herdís
lafsdttir Bjarni Kristfer Kristjnsson Catherine Chambers Georgette Leah Burns 《水产资源保护:海洋与淡水生态系统》2020,30(5):1012-1022
- Ecological damage by scuba divers has been extensively studied in marine ecosystems, particularly coral reefs, whereas the impacts on freshwater environments such as groundwater springs is unknown. In the Silfra groundwater fissure in Iceland, a vast increase in diver entries has occurred during the last decade, prompting concerns over potential ecosystem impacts and visitor carrying capacity.
- Here, a mixed‐method approach was used to assess the impacts of scuba diving in Silfra. (a) Divers were recorded under water to observe the mechanisms of diver‐related disturbances, (b) benthic material was collected along transects in Silfra and the undisturbed fissure Flosagjá to compare biofilm biomass and zoobenthic communities between and within fissures, and (c) the perceptions and experiences of stakeholders surrounding the dive tourism in Silfra were explored.
- Underwater observations showed that 91.4% of the divers caused at least a single disturbance, resulting in biofilm detachments and/or sediment stirring. Diver fins caused the most frequent disturbances, predominantly through fin‐generated currents but also by directly contacting the substrate. Benthic biofilm biomass was lower in Silfra than Flosagjá and exhibited a negative correlation with dive‐use. Some disturbance‐tolerant zoobenthic groups exhibited moderate to strong correlations with dive‐use.
- All stakeholders had negative perceptions towards increasing diver entries, but although entry limitation could improve tourism quality, disturbance might only minimally be reduced as springs like Silfra may be particularly sensitive.
- Springs are characteristically stable and uniform environments that can be vulnerable to disturbance. Their use for scuba diving should be carefully managed through a holistic approach and an active collaboration between all stakeholders.
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- Characterizing the composition of divers visiting different diving areas could help to design marine citizen science (MCS) projects that support biodiversity monitoring and marine conservation.
- Recreational scuba divers mostly prefer warm and clear waters with coral reefs, and based on the Duffus and Dearden’s wildlife tourism framework we hypothesized that a more popular diving area is visited mostly by generalist divers, whereas in a less popular diving area a higher proportion of specialist divers would be found.
- Recreational scuba divers were surveyed in diving centres at two diving areas, Rapa Nui (more popular, with warm and clear coral-reef waters) and the Chilean mainland (less popular, with productive and temperate–cold waters), to determine their diving profile, visiting profile, marine species knowledge, and interest and participation in MCS.
- Support for our hypothesis (generalist divers on Rapa Nui and specialist divers on the mainland) was weak, but recreational divers on Rapa Nui were mostly foreign visitors who come for single visits, whereas divers from the mainland were predominantly Chileans who return repeatedly to the diving area. In both diving areas the divers expressed a strong interest to be trained and to participate in MCS, but divers from Rapa Nui were interested in brief pre-dive inductions, whereas divers from the Chilean mainland preferred intensive training courses.
- Based on these findings we recommend specific MCS strategies for divers in both types of areas, e.g. simple protocols in more popular diving areas, with short pre-dive briefings for divers, and medium or long-term programmes in areas where most divers are local with high return rates. In these latter conditions more extensive training will be useful, which allows divers to gain more experience and assume higher responsibilities within an MCS project.
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- 1. Fibreglass was used to make specially designed reef enhancement units (REUs) for three reef sites in Singapore. Units were established in areas measuring approximately 20 × 50 m.
- 2. The units are compact and light enough to be deployed from small boats by scuba divers, and are suitable for shallow reefs with limited visibility.
- 3. The design of the REUs precludes excessive sediment build‐up on the settlement surfaces, while allowing water currents to flow through the system.
- 4. The REUs were monitored monthly over two years to observe community development and scleractinian coral recruitment on the exterior surfaces. Recruitment was compared between REUs and rubble quadrats at one study site.
- 5. The REUs were colonized by turf algae within the first month, followed by crustose coralline algae, macroalgae, ascidians and hydroids. At the end of two years, the percentage cover of crustose coralline algae at all three sites was more than 50%.
- 6. The first incidence of coral recruitment was six months post deployment, and recruitment rates at the end of the monitoring period ranged from 0.10 to 4.75 recruits per square metre for the three sites. Recruits show better survival and growth on REUs compared to rubble areas.
- 7. The most abundant recruit was Pocillopora damicornis, followed by favids, acroporids and poritids.
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- 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.
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Diego Lirman Beth Orlando Silvia Maciá Derek Manzello Louis Kaufman Patrick Biber Tahzay Jones 《水产资源保护:海洋与淡水生态系统》2003,13(2):121-135
- 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.
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- 1. The effects of trampling by visitors walking over the reef flat to snorkel or swim along the reef edge were studied at Ras Um Sidd, a popular fringing reef site at Sharm El Sheikh, and in the Ras Mohammed National Park, South Sinai, Egypt. Twelve stations showed a sequence of events linked to increased frequency and extent of trampling, with the intensities of trampling ranging from 0.1 to 324 tramplers m?2 yr?1.
- 2. Heavily trampled stations had a reduced coral cover (in particular branching corals), higher amounts of coral damage, less old dead coral, less obligate corallivorous fishes and more herbivores.
- 3. Wave exposure was crucial in determining the susceptibility of coral communities to trampling. Exposed communities were dominated by branching corals and were mechanically more resistant, since wave stress had favoured stockier growth forms.
- 4. The applicability of the ‘carrying capacity concept’ was investigated as a management tool for determining how much use is sustainable. Examination of the relationship between hard coral cover and intensity of trampling suggested that carrying capacity could be set at approximately 50 tramplers m?2 yr?1. The actual amount of damage caused by trampling showed a linear increase with increasing trampling intensities, so that the carrying capacity concept, as defined in this study, was not applicable to the relationship since no threshold existed. Instead, the ‘limits of acceptable change’ approach would be more practicable, with managers deciding what amount of coral damage they permit before limiting access. To establish meaningful limits of change, more knowledge is required about ecological as well as social consequences (e.g. visitor satisfaction) of such limits.
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D. Lirman A. Bowden‐kerby S. Schopmeyer B. Huntington T. Thyberg M. Gough T. Gough R. Gough Y. Gough 《水产资源保护:海洋与淡水生态系统》2010,20(7):773-781
- 1. Acropora cervicornis (staghorn coral) and Acropora palmata (elkhorn coral), once common features of shallow Caribbean reefs observed growing as large stands or thickets, are now found mainly as remnant pockets or isolated colonies at a fraction of their historical areal extent.
- 2. In February 2010, a large, surviving population of A. cervicornis was surveyed at Cabezos del Cayo, Punta Rusia, Dominican Republic to document its present condition and potential threats to its persistence.
- 3. The A. cervicornis surveyed at Cabezos del Cayo provides a rare glimpse of the habitat structure that these keystone components of coral reefs once provided. The staghorn population covers an area of 2 ha and is formed by interlocking skeletons of unusually large and thick A. cervicornis colonies.
- 4. The large size of its colonies (maximum branch length 250 cm; average linear length of live tissue 471 cm; maximum number of branch tips 141 per colony; maximum branch diameter 5 cm) and the complex open canopy of these colonies, have not been described, to our knowledge, in the recent literature.
- 5. The site is within Montecristi National Park but there is no active protection in this area and signs of overfishing are evident based on low fish abundance and complete lack of fish >20 cm in length.
- 6. The stressors associated with this population include significant predation by gastropods and fireworms, overgrowth by macroalgae, damselfish ‘gardening’ activities, and white band disease.
- 7. The management priority for the staghorn population at Cabezos del Cayo, Dominican Republic, should be to enforce the legal framework that is already in place for the protection of Montecristi National Park, limiting unsustainable and damaging fishing practices, and limiting land‐based sources of pollution associated with increasing population numbers and future coastal development. Copyright © 2010 John Wiley & Sons, Ltd.
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- 1. Rapid assessment protocols for determining and monitoring the status of any given coral reef are provided and include measuring: (a) standing stocks of functional indicator groups, (b) herbivore populations, (c) water‐column nutrient levels, (d) tissue C:N:P ratios, (e) algal physiological‐response assays, and (f) herbivory assays. These measurements can reveal quantitative tipping‐point levels beyond which resilience to undesirable phase shifts begins to become critically reduced. Universal tipping‐point approximations are reviewed for inorganic nutrients, and posited for the first time for herbivory.
- 2. The relative roles of top‐down and bottom‐up controls in determining benthic community structure and the health of coral reefs are especially important management concerns. This paper specifically addresses the top‐down effects of herbivory and bottom‐up effects of nutrient enrichment on critical indicator groups, i.e. reef‐building corals, crustose coralline algae, dense turf algae and frondose macroalgae.
- 3. A predominance of (a) massive corals and calcareous coralline algae relative to frondose macroalgae and algal turfs indicates a healthy spatially heterogeneous condition reflecting low nutrients and high herbivory. An abundance of (b) frondose macroalgae illustrates the least desirable condition of elevated nutrient levels and reduced herbivory, possibly reflecting pollution in concert with destructive herbivore fishing practices. High coverage of (c) coralline algae suggests healthy high herbivory levels, but problems with elevated nutrients that are inhibitory to some corals. Domination by (d) dense turf algae indicates desirably low nutrient levels, but an inadequate herbivory component.
- 4. The fast growth and turnover rates of fleshy algae compared to other reef organisms highlight their value as early warning indicators of reef degradation.
- 5. From a management perspective, levels of herbivory and nutrients rank among the most useful quantitative indicators of coral reef resilience; whereas, the degree of degradation and mortality are inferred from the above functional indicator groups of benthic primary producers.
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Dorothée Kopp Yolande Bouchon‐Navaro Max Louis David Mouillot Claude Bouchon 《水产资源保护:海洋与淡水生态系统》2010,20(5):516-524
- 1. The development of macroalgae to the detriment of corals is now one of the major threats to coral reefs. Herbivorous fishes are partly responsible for algal regulation on coral reefs and their overexploitation favours the shift from scleractinian coral‐dominated systems towards macroalgae‐dominated systems.
- 2. Marine protected areas (MPAs) that have been established worldwide may benefit coral reefs through the maintenance of high densities of herbivorous fishes which regulate algal growth.
- 3. The paper assesses whether small MPAs in the Caribbean are able to enhance herbivorous fish stock and by controlling macroalgae help to maintain reef ecosystems. A visual census using band‐transects was undertaken around Guadeloupe island where marine reserves have been in place since 1979. The effects of MPAs on both benthic communities and herbivorous fishes are examined.
- 4. Inside MPAs, herbivorous fish biomass was almost twice as high as outside MPAs and macroalgal cover was significantly lower. Fish size class distributions revealed that large individuals occurred mainly inside MPAs and that few male individuals were found outside MPAs. Copyright © 2010 John Wiley & Sons, Ltd.