Effects of Self-Guided Snorkeling Trails on Corals in a Tropical Marine Park

Abstract: Underwater trails are intended as interpretative tools in marine parks, but concentrating divers and snorkelers in defined areas may negatively affect the surrounding environment. We examined spatial and temporal patterns in the effects of use of underwater trails on coral reef flats in the Great Barrier Reef Marine Park, Australia. Changes in benthic assemblages were assessed on two new trails used by snorkelers, two unused (control) trails, and two undisturbed areas. Total percent coral cover, numbers of broken colonies, and living coral fragments were counted 6 months before and 6 months after the new trails began to be used. Spatial patterns of effects around concentrated nodes of use were determined by stratified sampling around and away from the interpretative signs within each trail. Despite comparatively low levels of use (approximately 15 snorkelers per trail per week), snorkelers caused significant damage to corals along the trails. Branching corals (non- Acropora branching corals and Millepora spp.) were most affected. More damage occurred near the interpretative signs than elsewhere on the trails. The numbers of broken branches and damaged coral colonies in the snorkeling trails increased rapidly but stabilized within 2 months of the commencement of use. There was no significant change in overall benthic assemblages within the trails after 6 months of use by snorkelers. Although concentrating snorkelers within confined trails caused increased damage to corals, the effects can be mitigated by appropriate design and placement of the trails and by managing the behavior of snorkelers. Interpretative information should warn users about the damage they may cause when swimming along the trails. Managing the behavior of snorkelers in the water is likely to be more effective in reducing damage than simply applying fixed limits to the amount of use the trails receive.     

A systematic study of some Black Corals species (Antipatharia,Hexacorallia) based on rDNA internal transcribed spacers sequences

A phylogenetic analysis based on rDNA internal transcribed spacers (ITS) sequences was performed on 15 species of black corals assigned to the genera Antipathes, Stichopathes, Cirrhipathes, Rhipidipathes, Antipathella, Myriopathes and Cupressopathes recorded from the Messina Strait (Mediterranean Sea) and the Bunaken Marine Park (Celebes Sea, Indonesia). The phylogenetic analysis shows that the examined species are grouped in two main branches corresponding to the families Antipathidae-Aphanipathidae and Myriopathidae. While among the Myriopathidae species there is a very small genetic distance, the Antipathidae-Aphanipathidae clade shows a high degree of divergence between different genera. According to this study, the taxon Antipathes? sp. 3 characterised by a bush-like corallum without a well-defined axis, probably belongs to a new undescribed genus of the family Antipathidae.     

Protection of Genetic Diversity and Maintenance of Connectivity among Reef Corals within Marine Protected Areas

Abstract: High‐latitude coral reefs (HLRs) are potentially vulnerable marine ecosystems facing well‐documented threats to tropical reefs and exposure to suboptimal temperatures and insolation. In addition, because of their geographic isolation, HLRs may have poor or erratic larval connections to tropical reefs and a reduced genetic diversity and capacity to respond to environmental change. On Australia's east coast, a system of marine protected areas (MPAs) has been established with the aim of conserving HLRs in part by providing sources of colonizing larvae. To examine the effectiveness of existing MPAs as networks for dispersal, we compared genetic diversity within and among the HLRs in MPAs and between these HLRs and tropical reefs on the southern Great Barrier Reef (GBR). The 2 coral species best represented on Australian HLRs (the brooding Pocillopora damicornis and the broadcast‐spawning Goniastrea australensis) exhibited sharply contrasting patterns of diversity and connectedness. For P. damicornis, the 8‐locus genetic and genotypic diversity declined dramatically with increasing latitude (N_a= 3.6–1.2, H_e= 0.3–0.03, N_g:N = 0.87–0.06), although population structure was consistent with recruitment derived largely from sexual reproduction (G_o:G_e= 1.28–0.55). Genetic differentiation was high among the HLRs (F_ST[SD]= 0.32 [0.08], p < 0.05) and between the GBR and the HLRs (F_ST= 0.24 [0.06], p < 0.05), which indicates these temperate populations are effectively closed. In contrast for G. australensis, 9‐locus genetic diversity was more consistent across reefs (N_a= 4.2–3.9, H_e= 0.3–0.26, N_g:N = 1–0.61), and there was no differentiation among regions (F_ST= 0.00 [0.004], p > 0.05), which implies the HLRs and the southern GBR are strongly interconnected. Our results demonstrate that although the current MPAs appear to capture most of the genetic diversity present within the HLR systems for these 2 species, their sharply contrasting patterns of connectivity indicate some taxa, such as P. damicornis, will be more vulnerable than others, and this disparity will provide challenges for future management.     

试论生态学的一门分支学科:环境耐性生态学

针对目前对生态学的学科分支情况,及生态学的发展趋势和环境灾害的启示,提出了"环境耐性生态学"这一生态学的分支学科.初步明确了这一分支学科的概念,提出了它的3个研究层次的研究框架,即耐性特征、耐性规律及提高耐性的方法与途径,指出了它的核心思想是:把自然环境看成是具有"生命"的系统,有一定的耐性能力和自我恢复能力,也具有自然免疫的特征和能力.同时,指出了当前急需确定的3个生态环境耐性指标,即容许侵蚀量、容许施肥量和容许承载量.     

A model of fish growth

A fish model based upon mass balances is set up. Several of the parameters have been determined by experiments. The remaining parameters are based upon literature values and it was not necessray to find any parameter by calibration. The model was validated with a completely acceptable result.The model includes equations giving the fish growth, the production of ammonia and organic matter, the oxygen consumption, and the influence to the temperature.The model can be used for management of fish farms and as a submodel for a total aquatic system.     

浅谈堆肥设备

随着堆肥技术在不同固体废弃物处理中的广泛应用,与之相关的堆肥设备得到了极大的发展,堆肥设备包括物料处理、翻堆、反应器和除臭设备。家庭堆肥器和小容量反应器堆肥系统是堆肥设备新的发展趋势。     

A spatial model of phytoplankton patchiness

The one-dimensional theory of critical-length scales of phytoplankton patchiness is developed to include phytoplankton growth and herbivore grazing as functions of time and space. The critical-length scale L _c for the pathch is then determined by the initial spatial distribution and concentration of the limiting nutrient and herbivores in addition to the daily averaged values of the growth and loss processes. The response of an initial phytoplankton patch to the stresses of turbulent diffusion, nutrient depletion, light periodicity, and nocturnal or continuous herbivore grazing is investigated numerically for several oceanic conditions. Nocturnal grazing, while less stressful on primary production than continous grazing, results in lower phytoplankton standing stocks. Increase in biomass of vertically migrating zooplankton results in a net loss of nutrient which might otherwise be egested, recycled, and utilized in the euphotic zone under continuous grazing conditions. The Ivlev constant is shown via sensitivity analysis to be a significant parameter ultimately influencing phytoplankton production. It is demonstrated numerically that diffusion of phytoplankton cells from areas of high concentration to low concentration prevents the local extinction of the standing stock, thereby rendering a positive herbivore grazing-threshold unnecessary for ecosystem stability.     

A Multidisciplinary Conceptualization of Conservation Opportunity

An opportunity represents an advantageous combination of circumstances that allows goals to be achieved. We reviewed the nature of opportunity and how it manifests in different subsystems (e.g., biophysical, social, political, economic) as conceptualized in other bodies of literature, including behavior, adoption, entrepreneur, public policy, and resilience literature. We then developed a multidisciplinary conceptualization of conservation opportunity. We identified 3 types of conservation opportunity: potential, actors remove barriers to problem solving by identifying the capabilities within the system that can be manipulated to create support for conservation action; traction, actors identify windows of opportunity that arise from exogenous shocks, events, or changes that remove barriers to solving problems; and existing, everything is in place for conservation action (i.e., no barriers exist) and an actor takes advantage of the existing circumstances to solve problems. Different leverage points characterize each type of opportunity. Thus, unique stages of opportunity identification or creation and exploitation exist: characterizing the system and defining problems; identifying potential solutions; assessing the feasibility of solutions; identifying or creating opportunities; and taking advantage of opportunities. These stages can be undertaken independently or as part of a situational analysis and typically comprise the first stage, but they can also be conducted iteratively throughout a conservation planning process. Four types of entrepreneur can be identified (business, policy, social, and conservation), each possessing attributes that enable them to identify or create opportunities and take advantage of them. We examined how different types of conservation opportunity manifest in a social–ecological system (the Great Barrier Reef) and how they can be taken advantage of. Our multidisciplinary conceptualization of conservation opportunity strengthens and legitimizes the concept.     

A characterization of sustainability with indicators

Economists favor the use of criteria to characterize sustainability. In practice, policy-makers use indicators, i.e., measurements based on the current economic state and decisions, representing given sustainability issues. In this paper, I introduce a criterion characterizing sustainability with indicators and thresholds acting as constraints. I interpret the thresholds as minimal rights to be guaranteed to all generations, and define sustainable trajectories as those satisfying all the constraints at all times. The new criterion is a “generalized” maximin criterion. The approach is applied to a simple production-consumption economy with non-renewable resources. To derive some policy recommendations on the use of indicators to deal with sustainability, I discuss the implications of such a criterion in terms of trade-off between sustainability thresholds, efficiency, and time-consistency. In particular, the resulting problem is time-inconsistent, and sustainability thresholds may be revised over time. Following the time-inconsistent policy based on indicators, with dynamic revision of the thresholds, may, however, result in a sustained utility path, and even in utility growth.     

A review of arsenicals in biology

The most toxic form of arsenic is arsine gas. Arsenite is also highly toxic and arsenate is moderately toxic. Arsine gas will lyse red blood cells, arsenite inactivates particular enzymes and arsenate uncouples oxidative phosphorylation. Arsenic does not appear to be a significant mutagen. Epidemiological studies have implicated arsenic as a cause of lung cancer and skin cancer, but arsenic generally does not induce cancer in laboratory animals. Arsenic may bioaccumulate in some plants and marine organisms. Bacteria can be resistant to arsenic by preventing arsenate from entering the cell (chromosomal resistance) or pumping arsenic out of the cell (plasmid resistance). Many different organisms, including mammals, have the ability to methylate inorganic arsenic. Biomethylation seems to be a mechanism of arsenic detoxification.