Chemical Behaviour of Calcium in Stabilized Oil Ash Reef Blocks After Five Years in the Ocean

Abstract

Reef blocks made from stabilized oil ash were taken from the sea after five years in the ocean to examine the chemical behaviour of calcium. Experiments included (1) determination of the calcium leaching rate and a comparison with the rate for unexposed blocks to test the validity of a diffusion model for predicting long term (5 years) leaching rates, (2) determination of the effect of biological cover (shell) on the leaching rate, (3) determination of the leaching rate of the core of exposed reef blocks, (4) determination of the calcium content in ‘ring areas’ - regions of discoloration observed in sectioned exposed reef blocks, and (5) determination of the leachable fraction of the total calcium in exposed reef blocks. Results showed the presence of a pronounced calcium discontinuity zone located 3–7 cm from the outside surface of the reef blocks. Cumulated calcium release rates ranged from 2.81–3.14 μmol cm^?2 day^?1 for original unexposed reef blocks and the core of exposed (in the ocean for five years) blocks, respectively, to 0.47–0.50 μmol cm^?2 day^?1 for outside (facing sea water) surfaces of exposed reef blocks. Tank leaching studies also showed that the presence or absence of hard biological cover (shells) had little or no effect on the calcium release rate. the diffusion model normally used in modelling the chemical behaviour of calcium cannot be used to predict the long term (five years) leaching of calcium. the core of the exposed blocks released calcium at a rate similar to new, unexposed reef block material. Overall, it appears that the calcium discontinuity zone is probably responsible for restricting the release of calcium and hence the failure of the diffusion model.     

Vermetid reefs in the Mediterranean Sea as archives of sea-level and surface temperature changes

Vermetid reefs are among the most important bioconstructions in the Mediterranean Sea, with a distribution restricted to the warmest part of the basin. Their structure, and vertical and geographical distribution make them good biological indicators of changes in sea level and sea-surface temperature over the last two millennia.     

Coral Reef Habitats as Surrogates of Species, Ecological Functions, and Ecosystem Services

Abstract: Habitat maps are often the core spatially consistent data set on which marine reserve networks are designed, but their efficacy as surrogates for species richness and applicability to other conservation measures is poorly understood. Combining an analysis of field survey data, literature review, and expert assessment by a multidisciplinary working group, we examined the degree to which Caribbean coastal habitats provide useful planning information on 4 conservation measures: species richness, the ecological functions of fish species, ecosystem processes, and ecosystem services. Approximately one‐quarter to one‐third of benthic invertebrate species and fish species (disaggregated by life phase; hereafter fish species) occurred in a single habitat, and Montastraea‐dominated forereefs consistently had the highest richness of all species, processes, and services. All 11 habitats were needed to represent all 277 fish species in the seascape, although reducing the conservation target to 95% of species approximately halved the number of habitats required to ensure representation. Species accumulation indices (SAIs) were used to compare the efficacy of surrogates and revealed that fish species were a more appropriate surrogate of benthic species (SAI = 71%) than benthic species were for fishes (SAI = 42%). Species of reef fishes were also distributed more widely across the seascape than invertebrates and therefore their use as a surrogate simultaneously included mangroves, sea grass, and coral reef habitats. Functional classes of fishes served as effective surrogates of fish and benthic species which, given their ease to survey, makes them a particularly useful measure for conservation planning. Ecosystem processes and services exhibited great redundancy among habitats and were ineffective as surrogates of species. Therefore, processes and services in this case were generally unsuitable for a complementarity‐based approach to reserve design. In contrast, the representation of species or functional classes ensured inclusion of all processes and services in the reserve network.     

Dynamic catch trends in the history of recreational spearfishing in Australia

The sustained decline in marine fisheries worldwide underscores the need to understand and monitor fisheries trends and fisher behavior. Recreational fisheries are unique in that they are not subject to the typical drivers that influence commercial and artisanal fisheries (e.g., markets or food security). Nevertheless, although exposed to a different set of drivers (i.e., interest or relaxation), recreational fisheries can contribute to fishery declines. Recreational fisheries are also difficult to assess due to an absence of past monitoring and traditional fisheries data. Therefore, we utilized a nontraditional data source (a chronology of spearfishing publications) to document historical trends in recreational spearfishing in Australia between 1952 and 2009. We extracted data on reported fish captures, advertising, and spearfisher commentary and used regression models and ordination analyses to assess historical change. The proportion of coastal fish captures reported declined approximately 80%, whereas the proportion of coral reef and pelagic fish reports increased 1750% and 560%, respectively. Catch composition shifted markedly from coastal temperate or subtropical fishes during the 1950s to 1970s to coral reef and pelagic species in the 1990s to 2000s. Advertising data and commentary by spearfishers indicated that pelagic fish species became desired targets. The mean weight of trophy coral reef fishes also declined significantly over the study period (from approximately 30–8 kg). Recreational fishing presents a highly dynamic social–ecological interface and a challenge for management. Our results emphasize the need for regulatory agencies to work closely with recreational fishing bodies to observe fisher behavior, detect shifts in target species or fishing intensity, and adapt regulatory measures. Tendencias Dinámicas de Captura en la Historia de la Pesca Recreativa con Arpón en Australia     

Speciation of nitrogen in the coral reef sedimentary environment of Lakshadweep archipelago,Indian ocean

This paper focuses on the spatial distributional profiles of different species of the important micronutrient element, nitrogen (nitrite, nitrate and total nitrogen) in various coral-reef sedimentary environment of Lakshadweep Archipelago. The relative abundance of the three forms of nitrogen was in the order, total-N???nitrate-N???nitrite-N. Relatively very low levels of nitrite in the different microenvironments of the islands are an indication of a higher rate of nitrification, so as to produce thermodynamically most stable form of nitrogen, namely nitrate under the condition of well-oxygenated shallow coastal/lagoon waters. A lagoon-ward enrichment pattern of total nitrogen in the lagoon transects of Agathy, Minicoy, Kadamath and Kiltan Islands also reflected the fact that the rate and space available for nitrogen fixation in shallow zones of the lagoon are high. Further, the nitrogenous waste materials produced from the reefs and surrounding environments have limited exchange with the sea, and all these factors, together with the organic nitrogen retention capacity of sediment types, contribute to total nitrogen.     

Adaptive Comanagement of a Marine Protected Area Network in Fiji

Adaptive management of natural resources is an iterative process of decision making whereby management strategies are progressively changed or adjusted in response to new information. Despite an increasing focus on the need for adaptive conservation strategies, there remain few applied examples. We describe the 9‐year process of adaptive comanagement of a marine protected area network in Kubulau District, Fiji. In 2011, a review of protected area boundaries and management rules was motivated by the need to enhance management effectiveness and the desire to improve resilience to climate change. Through a series of consultations, with the Wildlife Conservation Society providing scientific input to community decision making, the network of marine protected areas was reconfigured so as to maximize resilience and compliance. Factors identified as contributing to this outcome include well‐defined resource‐access rights; community respect for a flexible system of customary governance; long‐term commitment and presence of comanagement partners; supportive policy environment for comanagement; synthesis of traditional management approaches with systematic monitoring; and district‐wide coordination, which provided a broader spatial context for adaptive‐management decision making. Co‐Manejo Adaptativo de una Red de Áreas Marinas Protegidas en Fiyi     

The legacy of migration in response to climate stress: learning from the Gilbertese resettlement in the Solomon Islands

The long‐term threat of sea‐level rise to coral atoll and reef island communities in Kiribati, Tuvalu and other nations has raised the possibility of international migration. Historical resettlements in the Pacific may provide valuable insight into the long‐term effect of future climate change‐related migration on communities. This study evaluates the challenges faced by Gilbertese people resettled from modern‐day Kiribati to Ghizo in the Solomon Islands by the British colonial administration in the mid‐1900s. Drawing upon field interviews (n = 45) conducted in 2011 and the available historical literature, the study examines the circumstances of the initial failed resettlement in the equatorial Phoenix Islands, the subsequent relocation to Ghizo, and the recent concerns of the Gilbertese in Ghizo. Focus is placed on the struggle to recover from the 2007 tsunami that devastated the unprepared community. The analysis reveals that uncertainty about land tenure (raised by 61% of respondents) persists 60 years after resettlement, and is linked to the ability to recover from the tsunami, tensions with the Melanesian population, concerns over political representation, cultural decline, and education and employment opportunities. The Gilbertese experience can serve as a cautionary tale for policymakers considering mechanisms for facilitating climate change‐related migration.     

Making a Model Meaningful to Coral Reef Managers in a Developing Nation: a Case Study of Overfishing and Rock Anchoring in Indonesia

Abstract: Most of the world's coral reefs line the coasts of developing nations, where impacts from intense and destructive fishing practices form critical conservation issues for managers. Overfishing of herbivorous fishes can cause phase shifts to macroalgal dominance, and fishers’ use of rocks as anchors lowers coral cover, giving further competitive advantage to macroalgae. Overfishing and anchoring have been studied extensively, but the role of their interaction in lowering coral reef resilience has not been quantified formally. We analyzed the combined effects of overfishing and rock anchoring on a range of reef habitat types—varying from high coral and low macroalgae cover to low coral and high macroalgae cover—in a marine park in Indonesia. We parameterized a model of coral and algal dynamics with three intensities of anchoring and fishing pressure. Results of the model indicated that damage caused by rock anchoring was equal to or possibly more devastating to coral reefs in the area than the impact of overfishing. This is an important outcome for local managers, who usually have the funds to distribute less‐damaging anchors, but normally are unable to patrol regularly and effectively enough to reduce the impact of overfishing. We translated model results into an interactive visual tool that allows managers to explore the benefits of reducing anchoring frequency and fishing pressure. The potential consequences of inaction were made clear: the likelihood that any of the reef habitats will be dominated in the future by macroalgae rather than corals depends on reducing anchoring frequency, fishing pressure, or both. The tool provides a platform for strengthened relationships between managers and conservationists and can facilitate the uptake of recommendations regarding resource allocation and management actions. Conservation efforts for coral reefs in developing nations are likely to benefit from transforming model projections of habitat condition into tools local managers can understand and interact with.     

Exploring alternative states in ecological systems with a qualitative analysis of community feedback

Demonstrating and predicting the existence of alternative states in natural communities remains a challenge for ecologists and is essential for resource managers. Positive feedback is often presented as central in maintaining alternative ecosystem states, but no formal approach relates this part of theory to real world applications. Through qualitative modelling of community response to long-term perturbations, we define generic mechanistic links between positive feedback and the occurrence of alternative states. Positive feedback diminishes a system's overall resistance to change, and can create and maintain correlations in the relative abundance of variables that coincide with alternative states.Through specific models of the dynamics of Tasmanian rocky-reef communities, which are affected by climate and fishing and persist within alternative states, we demonstrate the ability of our theoretical framework to predict alternative states in ecosystems and inform management intervention. A qualitative knowledge of community structure permits a thorough analysis of system feedback and an assessment of the potential for an ecosystem to exhibit alternative states. We illustrate the usefulness of the approach to inform management priorities, and to focus monitoring and field research on the key drivers of ecosystem dynamics.     

The Effects of Habitat on Coral Bleaching Responses in Kenya

This study examines the bleaching responses of scleractinian corals at four sites in Kenya (Kanamai, Vipingo, Mombasa and Nyali) representing two distinct lagoon habitats (relatively shallow and relatively deep). Bleaching incidence was monitored for the whole coral community, while zooxanthellae densities and chlorophyll levels were monitored for target species (Pocillopora damicornis, Porites lutea, and Porites cylindrica) during a non-bleaching year (2006) and a year of mild-bleaching (2007). Differences in bleaching responses between habitats were observed, with shallower sites Kanamai and Vipingo exhibiting lower bleaching incidence than deeper sites Nyali and Mombasa. These shallower lagoons display more fluctuating thermal and light environments than the deeper sites, suggesting that corals in the shallower lagoons have acclimatized and/or adapted to the fluctuating environmental conditions they endure on a daily basis and have become more resistant to bleaching stress. In deeper sites that did exhibit higher bleaching (Mombasa and Nyali), it was found that coral recovery occurred more quickly in the protected area than in the non-protected area.