Assumption‐versus data‐based approaches to summarizing species’ ranges

For conservation decision making, species’ geographic distributions are mapped using various approaches. Some such efforts have downscaled versions of coarse‐resolution extent‐of‐occurrence maps to fine resolutions for conservation planning. We examined the quality of the extent‐of‐occurrence maps as range summaries and the utility of refining those maps into fine‐resolution distributional hypotheses. Extent‐of‐occurrence maps tend to be overly simple, omit many known and well‐documented populations, and likely frequently include many areas not holding populations. Refinement steps involve typological assumptions about habitat preferences and elevational ranges of species, which can introduce substantial error in estimates of species’ true areas of distribution. However, no model‐evaluation steps are taken to assess the predictive ability of these models, so model inaccuracies are not noticed. Whereas range summaries derived by these methods may be useful in coarse‐grained, global‐extent studies, their continued use in on‐the‐ground conservation applications at fine spatial resolutions is not advisable in light of reliance on assumptions, lack of real spatial resolution, and lack of testing. In contrast, data‐driven techniques that integrate primary data on biodiversity occurrence with remotely sensed data that summarize environmental dimensions (i.e., ecological niche modeling or species distribution modeling) offer data‐driven solutions based on a minimum of assumptions that can be evaluated and validated quantitatively to offer a well‐founded, widely accepted method for summarizing species’ distributional patterns for conservation applications.     

Semiconducting oxide photocatalysts for reduction of CO<Subscript>2</Subscript> to methanol

The explosive growth in anthropogenic energy consumption, coupled with the consequent environmental pollution, have been acknowledged as two impending challenges confronting humanity. Photocatalytic CO₂ reduction to produce value-added hydrocarbon fuels, by using abundant solar energy and redundant atmospheric CO₂, is an innovative way to satisfy global energy requirements whilst simultaneously reducing atmospheric CO₂ levels. Although this notion is several decades old, it has unfortunately been lingering in a state of infancy due to inherently poor CO₂-to-fuel conversion efficiencies, and the generation of low-value products (e.g., CO, HCHO). These pitfalls hamper this process from any potential commercial breakthrough and are primarily fuelled by the lack of progress in developing high-performance photocatalytic materials. Fortunately, the advent of nanotechnology has recently introduced many promising novel materials for this purpose. Here, we review photocatalysts with proven potential for converting CO₂ into methanol, a high-value, energy-dense hydrocarbon fuel that is easily transported using existing pipeline infrastructure. Methanol possesses multifarious applications in the automobile, industrial and petrochemical sector. In addition, the development of direct methanol fuel cells (DMFCs) has introduced the tantalizing prospect of using methanol as a medium for storing solar energy that is easily converted to electricity via DMFCs. As such, methanol is an ideal fuel, with numerous advantages over its counterparts. This article reviews several photocatalysts that have been reported for this environmentally sustainable process of converting CO₂ into methanol by photocatalysis. Specifically, the performance enhancement effected by adding dopant atoms, forming heterostructured composites and nanostructures, is investigated in terms of four key areas: (1) enhanced visible light sensitivity, (2) improved adsorption of reactants on the catalytic surface, (3) lowered electron–hole recombination and (4) increased CO₂ reduction kinetics. The trends deduced therein are invaluable for researchers developing novel photocatalytic materials, which will utilize sunlight to convert CO₂ into methanol with enhanced efficiency, thus ushering in the era of a green methanol-based economy.     

Adaptation strategies of the corallimorpharian <Emphasis Type="Italic">Rhodactis rhodostoma</Emphasis> to irradiance and temperature

Corallimorpharians may dominate some habitats on coral reefs and compete with stony corals for access to light, yet little is known concerning their photosynthetic traits. At Eilat in the northern Red Sea, we observed that the abundance of individuals of the corallimorpharian Rhodactis rhodostoma decreased significantly with depth on the reef slope. Field and laboratory experiments revealed that they employ several mechanisms of photoadaptation to high irradiance on the shallow reef flat. Their endosymbiotic microalgae (zooxanthellae) varied significantly in both abundance and chlorophyll content with level of irradiance. Use of a diving pulse amplitude modulated fluorometer revealed that the zooxanthellae of R. rhodostoma effectively disperse excess light energy by expressing significantly higher values of non-photochemical quenching and maximum excitation pressure on photosystem II when experimentally exposed to high light (HL) versus low light (LL). Host corallimorpharian tissues mediated this response by shielding the algal symbionts from high irradiance. The endoderm of host tentacles thickened significantly and microalgal cells were located further from the mesoglea in HL than in LL. The clades of zooxanthellae hosted by the corallimorpharians also varied with depth. In shallow water, all sampled individuals hosted clade C zooxanthellae, while in deep water the majority hosted clade D. The photosynthetic output of individuals of R. rhodostoma was less affected by HL than was that of a stony coral examined. When exposed to both high temperature (HT) and HL, individuals of R. rhodostoma reduced their maximum quantum yield, but not when exposed to HL at low temperature (LT). In contrast, colonies of the scleractinian coral Favia favus reduced their photosynthetic output when exposed to HL in both temperature regimes. After 2 weeks of HT stress, R. rhodostoma polyps appeared to bleach completely but re-established their zooxanthella populations upon return to ambient temperature. We conclude that mechanisms of photoadaptation to high irradiance employed by both the endosymbiotic zooxanthellae and host corallimorpharians may explain in part the abundance of R. rhodostoma on some shallow reef flats. The ability to survive for weeks at HT while bleached also may allow corallimorpharians to repopulate shallow reef areas where scleractinians have been killed by thermal stress. B. Kuguru and G. Winters contributed equally to this work.     

Countering resistance to protected‐area extension

The establishment of protected areas is a critical strategy for conserving biodiversity. Key policy directives like the Aichi targets seek to expand protected areas to 17% of Earth's land surface, with calls by some conservation biologists for much more. However, in places such as the United States, Germany, and Australia, attempts to increase protected areas are meeting strong resistance from communities, industry groups, and governments. We examined case studies of such resistance in Victoria, Australia, Bavaria, Germany, and Florida, United States. We considered 4 ways to tackle this problem. First, broaden the case for protected areas beyond nature conservation to include economic, human health, and other benefits, and translate these into a persuasive business case for protected areas. Second, better communicate the conservation values of protected areas. This should include highlighting how many species, communities, and ecosystems have been conserved by protected areas and the counterfactual (i.e., what would have been lost without protected area establishment). Third, consider zoning of activities to ensure the maintenance of effective management. Finally, remind citizens to think about conservation when they vote, including holding politicians accountable for their environmental promises. Without tackling resistance to expanding the protected estate, it will be impossible to reach conservation targets, and this will undermine attempts to stem the global extinction crisis.     

Biotic resistance to green crab, <Emphasis Type="Italic">Carcinus maenas</Emphasis>, in California bays

The distribution of the introduced European green crab, Carcinus maenas, was investigated in the central California embayments of Bodega Bay Harbor (BBH), Tomales Bay, and Bolinas Lagoon using baited traps and snorkel surveys. Adult green crabs were very spatially limited in all three embayments and occurred primarily in warm, shallow areas that lacked large native Cancer spp. crabs. The green crabs that were found in closest proximity to populations of Cancer spp. exhibited high levels of limb damage and loss; damage was strongly correlated with low ratios of intertidal area: edge, indicative of narrow areas of intertidal that are more easily accessed by large Cancer spp. moving up to forage during periods of tidal inundation. Up to 70% of the green crabs tethered in areas of BBH that are utilized by Cancer spp. experienced limb loss, while those tethered in the marsh, where there are no Cancer spp., were undamaged. The results suggest that the potential distribution of green crabs in the northeastern Pacific will be far less than has been predicted, and that their impacts may be largely attenuated through predation by and competition with native crab species.     

Gonad morphology and oocyte development in<Emphasis Type="Italic"> Pseudocalanus</Emphasis> spp. in relation to spawning activity

Gonad maturation processes were studied in Pseudocalanus spp. females from Georges Bank and Cape Cod Bay (northwest Atlantic) using a combination of morphological analysis and experiments. For light microscopy of the oocytes, females of different maturation stages were preserved immediately after capture. The maturation processes during the spawning cycle were described from observations of live females which were exposed to feeding and starvation at two temperatures, 8 and 15°C, for 12 days. The gonad morphology of these females was examined in 24 h intervals, and spawning events were recorded. Both light microscopy and whole animal observation revealed that oocytes during maturation change in shape and size, in the morphology of the nucleus, and in the appearance of the ooplasm. Due to these modifications of oocyte morphology and due to oocyte migration, the morphology of the gonads changed distinctly during a spawning cycle. Five oocyte development stages were identified by light microscopy and related to a macroscopic system of four gonad development stages, that can be applied to whole animals and allows the identification of females ready to spawn. The experiment showed that food and temperature had strong effects on gonad maturation processes. High proportions of mature females were found when food was available, whereas the proportion of immature females increased shortly after exposure to starvation. Compared to 15°C, gonad maturation at 8°C was prolonged and thus spawning frequency was lower. The final maturation processes at food saturated conditions were slower than the embryonic development, and no indication was found that mature oocytes are stored in the diverticula waiting to be released. The duration of the interspawning interval would thus be determined by the duration of final oocyte maturation which is dependent on both temperature and food supply.Communicated by O. Kinne, Oldendorf/Luhe     

Larval settlement and metamorphosis of the mussel <Emphasis Type="Italic">Mytilus galloprovincialis</Emphasis> in response to biofilms

Biofilms were allowed to develop on glass slips immersed 1.0–1.5 m below the sea surface in Tachibana Bay, Nagasaki, Japan, for different periods of time from November 2003 to January 2005. The effects of age, immersion month, dry weight, bacterial and diatom densities of these biofilms on the settlement and metamorphosis of pediveliger larvae of the mussel Mytilus galloprovincialis were investigated in the laboratory. Furthermore, biofilms were subjected to various treatments to investigate the nature of the settlement and metamorphosis cue in the biofilm. Pediveliger larvae of the mussel settled and metamorphosed in response to biofilms. Settlement and metamorphosis to the post-larval stage significantly increased with the biofilm age. In addition, the biofilm activity varied depending on the immersion month (season), e.g., for biofilms with the same age, those immersed between June and August had higher activities than those immersed between November and March. The activity of the biofilm also positively correlated with the dry weight, bacterial and diatom densities. These three quantitative parameters of the biofilm were significantly affected by the film age but were not affected by the immersion month, suggesting that other parameters (e.g., community structures, extracellular products) also affected the inductive activity of the biofilm. The fixative agents (formalin and glutaraldehyde), heat, ethanol, ultraviolet irradiation and antibiotics treatments of the biofilm resulted in significant reduction or loss of its inductive activity. The survival of bacterial cells in the treated films where activities were either reduced or lost also decreased significantly. No settlement and metamorphosis were obtained when larvae were exposed to the conditioned water of the biofilm. Thus, larvae of M. galloprovincialis settled and metamorphosed in response to a cue produced by living bacteria in the biofilm. The cue may be a bacterial extracellular product which was susceptible to the above treatments.     

Gene expression profiles of the swimming crab <Emphasis Type="Italic">Portunus trituberculatus</Emphasis> exposed to salinity stress

The swimming crab, Portunus trituberculatus, is an important marine fishery and aquaculture species. Although P. trituberculatus is a euryhaline species, water salinity condition influenced its distribution, migration route, and artificial propagations. To investigate gene expression in the P. trituberculatus exposed to different salinity stresses, 2426 expressed sequence tags (ESTs) from gill cDNA library were selected to spot on a cDNA microarray chip. In total, 417 differentially expressed genes were identified and grouped into eight clusters by hierarchical clustering analysis. Approximately 71.5% of grouped genes belonged to three independent expression patterns, indicating that these three expression patterns may represent three important stress tolerance pathways or networks in P. trituberculatus. Moreover, our cDNA microarray data suggested that there were differences in gene expression patterns of P. trituberculatus for low salinity and high salinity acclimation, suggesting that two salinity challenges resulted in a wide variation of gene expression in P. trituberculatus. In addition, a series of genes such as CCAAT/enhancer-binding protein, Na/K ATPase β-subunit, and heat shock proteins (HSPs) genes were suggested to be key elements during salinity acclimation process. Overall, this work represented an important step toward understanding the molecular processes and mechanisms involved in salinity acclimation of the swimming crab.     

An “effluent” charge approach to aircraft noise abatement

This paper is concerned with the control of aircraft noise. Some brief remarks are made on the relationship of aircraft noise problems to the theoretical approaches to externalities. We note in particular that an effluent charge is the most practical way to deal with the problem. A linear programming technique is used to find the bundle of noise-reducing options that minimizes the cost of achieving noise reduction goals, given an upper limit on service reduction. A rate-of-return criterion is imposed on the l.p. solution. Shadow prices are used to generate charges on the airlines. This provides a stimulus for abatement without dictating actual methods. Implicit in the cost parameters are prices of aircraft fuel. We assess the attractiveness of the abatement options with increasing fuel prices. The mechanics of the actual implementation of the charge in the airline industry is examined. We conclude that the institution of a plan such as the one proposed here will provide control of aircraft noise in a socially efficient manner.     

Chlorophyll fluorescence measures of seagrasses <Emphasis Type="Italic">Halophila ovalis</Emphasis> and <Emphasis Type="Italic">Zostera capricorni</Emphasis> reveal differences in response to experimental shading

In coastal waters and estuaries, seagrass meadows are often subject to light deprivation over short time scales (days to weeks) in response to increased turbidity from anthropogenic disturbances. Seagrasses may exhibit negative physiological responses to light deprivation and suffer stress, or tolerate such stresses through photo-adaptation of physiological processes allowing more efficient use of low light. Pulse Amplitude Modulated (PAM) fluorometery has been used to rapidly assess changes in photosynthetic responses along in situ gradients in light. In this study, however, light is experimentally manipulated in the field to examine the photosynthesis of Halophila ovalis and Zostera capricorni. We aimed to evaluate the tolerance of these seagrasses to short-term light reductions. The seagrasses were subject to four light treatments, 0, 5, 60, and 90% shading, for a period of 14 days. In both species, as shading increased the photosynthetic variables significantly (P < 0.05) decreased by up to 40% for maximum electron transport rates (ETR_max) and 70% for saturating irradiances (E_k). Photosynthetic efficiencies (α) and effective quantum yields (ΔF/Fm′) increased significantly (P < 0.05), in both species, for 90% shaded plants compared with 0% shaded plants. H. ovalis was more sensitive to 90% shading than Z. capricorni, showing greater reductions in ETR_max, indicative of a reduced photosynthetic capacity. An increase in E_k, Fm′ and ΔF/Fm′ for H. ovalis and Z. capricorni under 90% shading suggested an increase in photochemical efficiency and a more efficient use of low-photon flux, consistent with photo-acclimation to shading. Similar responses were found along a depth gradient from 0 to10 m, where depth related changes in ETR_max and E_k in H. ovalis implied a strong difference of irradiance history between depths of 0 and 5–10 m. The results suggest that H. ovalis is more vulnerable to light deprivation than Z. capricorni and that H. ovalis, at depths of 5–10 m, would be more vulnerable to light deprivation than intertidal populations. Both species showed a strong degree of photo-adaptation to light manipulation that may enable them to tolerate and adapt to short-term reductions in light. These consistent responses to changes in light suggest that photosynthetic variables can be used to rapidly assess the status of seagrasses when subjected to sudden and prolonged periods of reduced light.     

Identifying impediments to long‐distance mammal migrations

In much of the world, the persistence of long‐distance migrations by mammals is threatened by development. Even where human population density is relatively low, there are roads, fencing, and energy development that present barriers to animal movement. If we are to conserve species that rely on long‐distance migration, then it is critical that we identify existing migration impediments. To delineate stopover sites associated with anthropogenic development, we applied Brownian bridge movement models to high‐frequency locations of pronghorn (Antilocapra americana) in the Greater Yellowstone Ecosystem. We then used resource utilization functions to assess the threats to long‐distance migration of pronghorn that were due to fences and highways. Migrating pronghorn avoided dense developments of natural gas fields. Highways with relatively high volumes of traffic and woven‐wire sheep fence acted as complete barriers. At crossings with known migration bottlenecks, use of high?quality forage and shrub habitat by pronghorn as they approached the highway was lower than expected based on availability of those resources. In contrast, pronghorn consistently utilized high?quality forage close to the highway at crossings with no known migration bottlenecks. Our findings demonstrate the importance of minimizing development in migration corridors in the future and of mitigating existing pressure on migratory animals by removing barriers, reducing the development footprint, or installing crossing structures. Identificación de los Impedimentos para las Migraciones de Larga Distancia de Mamíferos