Lag Effects in the Impacts of Mass Coral Bleaching on Coral Reef Fish, Fisheries, and Ecosystems

Abstract:  Recent episodes of coral bleaching have led to wide-scale loss of reef corals and raised concerns over the effectiveness of existing conservation and management efforts. The 1998 bleaching event was most severe in the western Indian Ocean, where coral declined by up to 90% in some locations. Using fisheries-independent data, we assessed the long-term impacts of this event on fishery target species in the Seychelles, the overall size structure of the fish assemblage, and the effectiveness of two marine protected areas (MPAs) in protecting fish communities. The biomass of fished species above the size retained in fish traps changed little between 1994 and 2005, indicating no current effect on fishery yields. Biomass remained higher in MPAs, indicating they were effective in protecting fish stocks. Nevertheless, the size structure of the fish communities, as described with size-spectra analysis, changed in both fished areas and MPAs, with a decline in smaller fish (<30 cm) and an increase in larger fish (>45 cm). We believe this represents a time-lag response to a reduction in reef structural complexity brought about because fishes are being lost through natural mortality and fishing, and are not being replaced by juveniles. This effect is expected to be greater in terms of fisheries productivity and, because congruent patterns are observed for herbivores, suggests that MPAs do not offer coral reefs long-term resilience to bleaching events. Corallivores and planktivores declined strikingly in abundance, particularly in MPAs, and this decline was associated with a similar pattern of decline in their preferred corals. We suggest that climate-mediated disturbances, such as coral bleaching, be at the fore of conservation planning for coral reefs.     

Effects of Habitat Fragmentation on Effective Population Size in the Endangered Rio Grande Silvery Minnow

Abstract:  We assessed spatial and temporal patterns of genetic diversity to evaluate effects of river fragmentation on remnant populations of the federally endangered Rio Grande silvery minnow ( Hybognathus amarus ). Analysis of microsatellite and mitochondrial DNA detected little spatial genetic structure over the current geographic range, consistent with high gene flow despite fragmentation by dams. Maximum-likelihood analysis of temporal genetic data indicated, however, that present-day effective population size ( N_eV ) of the largest extant population of this species was 78 and the ratio of effective size to adult numbers ( N_eV/N ) was ∼ 0.001 during the study period (1999 to 2001). Coalescent-based analytical methods provided an estimate of historical (river fragmentation was completed in 1975) effective size ( N_eI  ) that ranged between 10⁵ and 10⁶. We propose that disparity between contemporary and historical estimates of N_e and low contemporary N_e/N result from recent changes in demography related to river fragmentation. Rio Grande silvery minnows produce pelagic eggs and larvae subject to downstream transport through diversion dams. This life-history feature results in heavy losses of yearly reproductive effort to emigration and mortality, and extremely large variance in reproductive success among individuals and spawning localities. Interaction of pelagic early life history and river fragmentation has altered demographic and genetic dynamics of remnant populations and reduced N_e to critically low values over ecological time.     

Knowing and Doing: Research Leading to Action in the Conservation of Forest Genetic Diversity of Patagonian Temperate Forests

Abstract:  Researchers dealing with conservation subjects usually do not put the results of their work into practice, even when the primary purpose of their research is the preservation of biodiversity. In the South American temperate forests we identified an area with the highest genetic diversity in Argentina of Nothofagus nervosa, one of the most relevant southern beech species. Based on the information of our scientific study and our recommendations, the authorities of Lanin National Park changed the protection status of this area to avoid logging. The new forestry management plans include consideration of high genetic diversity in decisions on where logging will be allowed. Results of our initial genetic study induced the analysis of biodiversity at the species and ecosystems levels, which yielded results similar to our genetic studies. A strong connection among researchers and managers from the onset of our study and the awareness of the former about the importance of the implementation of the research work were key to bridging the gap between conservation research and conservation practice.     

Conservation Assessment of Southern South American Freshwater Ecoregions on the Basis of the Distribution and Genetic Diversity of Crabs from the Genus Aegla

Abstract:  We assessed the conservation priority of 18 freshwater ecoregions in southern South America on the basis of Aegla (genus of freshwater crabs) genetic diversity and distribution. Geographical distributions for 66 Aegla species were taken from the literature and plotted against ecoregions and main river basins of southern South America. Species richness and number of threatened and endemic species were calculated for each area. To assess taxonomic and phylogenetic diversity, we generated a molecular phylogeny based on DNA sequences for one nuclear (28S) and 4 mitochondrial (12S, 16S, COI, and COII) genes. All species richness and phylogenetic methods agreed, to a large extent, in their rankings of the importance of conservation areas, as indicated by the Spearman's rank correlation coefficient ( p < 0.01); nonetheless, some of the lowest correlations were observed between taxonomic and phylogenetic diversity indices. The 5 ecoregions of the Laguna dos Patos Basin (Eastern Brazil), Central Chile, South Brazilian Coast, Chilean Lakes, and Subtropical Potamic Axis (northern Argentina and southern Uruguay and Paraguay) had the highest biodiversity scores. Conservation of these regions will preserve the largest number of species and the greatest amount of genetic diversity within the South American freshwater Aegla fauna. Biodiversity across rivers and within areas was heterogeneously distributed in the ecoregions of Upper Paraná, Ribeira do Iguape, Upper Uruguay, and South Brazilian Coast (i.e., one river showed significantly more biodiversity than any other river from the same ecoregion), but homogeneously distributed in the other ecoregions. Hence, conservation plans in the former regions will potentially require less effort than plans in the latter regions.     

Effects of Knowledge of an Endangered Species on Recreationists’ Attitudes and Stated Behaviors and the Significance of Management Compliance for Ohlone Tiger Beetle Conservation

Recreation is a leading cause of species decline on public lands, yet sometimes it can be used as a tool for conservation. Engagement in recreational activities, such as hiking and biking, in endangered species habitats may even enhance public support for conservation efforts. We used the case of the endangered Ohlone tiger beetle (Cicindela ohlone) to investigate the effect of biking and hiking on the beetle's behavior and the role of recreationists’ knowledge of and attitudes toward Ohlone tiger beetle in conservation of the species. In Inclusion Area A on the University of California Santa Cruz (U.S.A.) campus, adult Ohlone tiger beetles mate and forage in areas with bare ground, particularly on recreational trails; however, recreation disrupts these activities. We tested the effect of recreation on Ohlone tiger beetles by observing beetle behavior on trails as people walked and road bikes at slow and fast speed and on trails with no recreation. We also surveyed recreationists to investigate how their knowledge of the beetle affected their attitudes toward conservation of the beetle and stated compliance with regulations aimed at beetle conservation. Fast cycling caused the beetles to fly off the trail more often and to fly farther than slow cycling or hiking. Slow cycling and hiking did not differ in their effect on the number of times and distance the beetles flew off the trail. Recreationists’ knowledge of the beetle led to increased stated compliance with regulations, and this stated compliance is likely to have tangible conservation outcomes for the beetle. Our results suggest management and education can mitigate the negative effect of recreation and promote conservation of endangered species. Efectos del Conocimiento de una Especie en Peligro sobre las Actitudes y Comportamientos Declarados de los Recreacionistas y el Significado del Manejo de la Conformidad para la Conservación del Escarabajo Tigre de Ohlone     

稀土的生物效应与农用稀土的累积影响

综述稀土元素的环境行为、累积影响、生物富集和生物效应,从动植物对稀土元素的生物富集及其产生的负面效应,探讨了农业应用稀土在土壤中累积后对生态环境可能产生的影响     

Founder Effects,Inbreeding, and Loss of Genetic Diversity in Four Avian Reintroduction Programs

Abstract: The number of individuals translocated and released as part of a reintroduction is often small, as is the final established population, because the reintroduction site is typically small. Small founder and small resulting populations can result in population bottlenecks, which are associated with increased rates of inbreeding and loss of genetic diversity, both of which can affect the long‐term viability of reintroduced populations. I used information derived from pedigrees of four monogamous bird species reintroduced onto two different islands (220 and 259 ha) in New Zealand to compare the pattern of inbreeding and loss of genetic diversity among the reintroduced populations. Although reintroduced populations founded with few individuals had higher levels of inbreeding, as predicted, other factors, including biased sex ratio and skewed breeding success, contributed to high levels of inbreeding and loss of genetic diversity. Of the 10–58 individuals released, 4–25 genetic founders contributed at least one living descendent and yielded approximately 3–11 founder–genome equivalents (number of genetic founders assuming an equal contribution of offspring and no random loss of alleles across generations) after seven breeding seasons. This range is much lower than the 20 founder–genome equivalents recommended for captive‐bred populations. Although the level of inbreeding in one reintroduced population initially reached three times that of a closely related species, the long‐term estimated rate of inbreeding of this one population was approximately one‐third that of the other species due to differences in carrying capacities of the respective reintroduction sites. The increasing number of reintroductions to suitable areas that are smaller than those I examined here suggests that it might be useful to develop long‐term strategies and guidelines for reintroduction programs, which would minimize inbreeding and maintain genetic diversity.     

Joint Effects of Inbreeding and Local Adaptation on the Evolution of Genetic Load after Fragmentation

Abstract: Disruption of gene flow among demes after landscape fragmentation can facilitate local adaptation but increase the effect of genetic drift and inbreeding. The joint effects of these conflicting forces on the mean fitness of individuals in a population are unknown. Through simulations, we explored the effect of increased isolation on the evolution of genetic load over the short and long term when fitness depends in part on local adaptation. We ignored genetic effects on demography. We modeled complex genomes, where a subset of the loci were under divergent selection in different localities. When a fraction of the loci were under heterogeneous selection, isolation increased mean fitness in larger demes made up of hundreds of individuals because of improved local adaptation. In smaller demes of tens of individuals, increased isolation improved local adaptation very little and reduced overall fitness. Short‐term improvement of mean fitness after fragmentation may not be indicative of the long‐term evolution of fitness. Whatever the deme size and potential for local adaptation, migration of one or two individuals per generation minimized the genetic load in general. The slow dynamics of mean fitness following fragmentation suggests that conservation measures should be implemented before the consequences of isolation on the genetic load become of concern.     

Global Effects of Local Human Population Density and Distance to Markets on the Condition of Coral Reef Fisheries

Coral reef fisheries support the livelihoods of millions of people but have been severely and negatively affected by anthropogenic activities. We conducted a systematic review of published data on the biomass of coral reef fishes to explore how the condition of reef fisheries is related to the density of local human populations, proximity of the reef to markets, and key environmental variables (including broad geomorphologic reef type, reef area, and net productivity). When only population density and environmental covariates were considered, high variability in fisheries conditions at low human population densities resulted in relatively weak explanatory models. The presence or absence of human settlements, habitat type, and distance to fish markets provided a much stronger explanatory model for the condition of reef fisheries. Fish biomass remained relatively low within 14 km of markets, then biomass increased exponentially as distance from reefs to markets increased. Our results suggest the need for an increased science and policy focus on markets as both a key driver of the condition of reef fisheries and a potential source of solutions. Efectos Globales de la Densidad de Población Humana Local y la Distancia a los Mercados sobre la Condición de Pesquerías en Arrecifes de Coral     

A Meta-Analysis of the Effects of Ultraviolet B Radiation and Its Synergistic Interactions with pH, Contaminants, and Disease on Amphibian Survival

Abstract:  Human alterations to natural systems have resulted in a loss of biological diversity around the world. Amphibian population losses have been more severe than those of birds and mammals. Amphibian population declines are likely due to many factors including habitat loss, disease, contaminants, introduced species and ultraviolet-B (UVB) radiation. The effect of UVB, however, varies widely among species and can vary within populations of the same species or at different life-history stages. This variation has often led to opposing conclusions about how UVB affects amphibians. We used meta-analysis techniques to explore the overall effects of UVB radiation on survival in amphibians. We also used recently developed factorial meta-analytic techniques to quantify potential interactions between UVB radiation and other stressors on amphibians. Ultraviolet-B radiation reduced survival of amphibians by 1.9-fold compared with shielded controls. Larvae were more susceptible to damage from UVB radiation compared with embryos, and salamanders were more susceptible compared with frogs and toads. Furthermore, UVB radiation interacted synergistically with other environmental stressors and resulted in greater than additive effects on survival when 2 stressors were present. Our results suggest that UVB radiation is an important stressor in amphibians, particularly in light of potential synergisms between UVB and other stressors in amphibian habitats.