Biogeography of Recently Extinct Marine Species: Implications for Conservation

At least fifteen marine and coastal animal species have become extinct since the end of the Pleistocene. Analyses of the number of marine biogeographical provinces occupied by these species show that, contrary to the prevailing view that extinction is usually associated with a small range, at least five species (33%) had large ranges encompassing parts of two or more provinces. At least eight species occurred in areas that served as geographical refuges for taxa during the Pliocene and early Pleistocene. These refuges, in which primary planktonic productivity is generally very high, include the northwestern Atlantic and North Pacific. Extinctions in the northwestern Atlantic (four species) may be partly responsible for the subsequent success of human-introduced species in subtidal and open-coast intertidal habitats. Regions of high productivity deserve priority among marine areas to be protected from overexploitation and habitat destruction.     

A Decision Framework for the Adaptive Management of an Exploited Species with Implications for Marine Reserves

Abstract:  Marine reserves have both conservation and fishery benefits. Nevertheless, there are no general criteria about when and where to establish new reserves, how to evaluate their efficacy, and how to conduct adaptive management to achieve conservation goals. We applied a decision-theory framework to optimally allocate conservation resources between improving data on population status and establishing a reserve for species conservation. Our goal was to maximize reserve benefits given the constraints of a population growth rate that would permit sustainability of resources. We illustrate our decision framework with a retrospective analysis of a 7-year time series on abundance of the leopard grouper ( Mycteroperca rosacea ) in the Sea of Cortés, Mexico. We used the lower bound of the distribution of the population growth rate ( λ ) as a decision rule for determining how many years of monitoring are needed to detect reserve effects. We determined the minimum time frame needed to estimate λ based on a stated level of risk tolerance for four sites. As expected, the coefficient of variation for the λ declined with the number of years of data. This increased precision with additional years of data resulted from the high degree of annual variability in the system. Where populations were slow to respond to reserves, more data were needed to detect a positive λ value. For the leopard grouper case study, confidence in the estimate of λ increased with the number of years of data. Our decision framework may be used to identify the minimum number of years of data needed before a management decision about reserve establishment could be made that is reasonably likely to meet its management objectives.     

Conservation Benefits of Temperate Marine Protected Areas: Variation among Fish Species

Abstract:  Marine protected areas, and other fishery management systems that impart partial or total protection from fishing, are increasingly advocated as an essential management tool to ensure the sustainable use of marine resources. Beneficial effects for fish species are well documented for tropical and reef systems, but the effects of marine protected areas remain largely untested in temperate waters. We compared trends in sport-fishing catches of nine fish species in an area influenced by a large (500-km²) towed-fishing-gear restriction zone and in adjacent areas under conventional fishery management controls. Over the period 1973–2002 the mean reported weight of above-average-sized (trophy) fish of species with early age at maturity and limited home range was greatest within the area influenced by the fishing-gear restriction zone. The reported weight of trophy fish of species that mature early also declined less and more slowly over time within the area influenced by the fishing-gear restriction zone. Importantly, the mean reported weight of trophy fish of species that mature late and those that undertake extensive spatial movements declined at the same rate in all areas. Hence these species are likely to require protected areas >500 km² for effective protection. Our results also indicated that fish species with a localized distribution or high site fidelity may require additional protection from sport fishing to prevent declines in the number or size of fish within the local population.     

Postfledging Dispersal of White-crowned Pigeons: Implications for Conservation of Deciduous Seasonal Forests in the Florida Keys

From 1988 to 1991, we studied the postfledging dispersal of 31 radio-tagged White-crowned Pigeons ( Columba leucocephala ) from three natal keys in Florida Bay. Immature birds dispersed from the natal keys at 26–45 days after batching, and most young dispersed more than 20 km during the first 10 days postdispersal. Dispersing birds flew either north to the Florida mainland or east to northeast to the mainline Florida Keys. On the mainland, immature birds fed nearly exclusively within Everglades National Park or an adjacent state wildlife management area. On the mainline keys, White-crowned Pigeons selectively used 5.01–20 ha forest fragments (p < 0.10) during the first 72 hours postdispersal. After this period, dispersing birds showed no preference among fragment size classes but used deciduous seasonal forests more frequently than suburban habitat(p < 0.10). The spatial pattern of dispersal on the mainline keys suggests that, during the first 72 hours postdispersal. White-crowned Pigeons are not able to reach northern Key Largo, where 69% of the deciduous seasonal forests are protected in state or federal ownership. Protection of large forest fragments, especially on southern Key Largo, should be a priority for maintaining populations of White-crowned Pigeons. These forests provide a series of "stepping stones" that enable dispersing immature White-crowned Pigeons to fly to more distant areas where habitat availability is less restricted. This species is threatened in Florida and may play an important role in maintaining plant species diversity in the seasonal deciduous forests of south Florida by dispersing seeds of at least 37 species of trees and shrubs. Protection of sufficient habitat to allow successful postfledging dispersal of this important seed disperser will also protect the ecosystem's biodiversity.     

Offsets and Conservation of the Species of the EU Habitats and Birds Directives

Biodiversity offsets are intended to achieve no net loss of biodiversity due to economic and human development. A variety of biodiversity components are addressed by offset policies. It is required that loss of protected species due to development be offset under the EU Habitats and Birds Directives in Europe. We call this type of offset a species‐equality offset because the offset pertains to the same species affected by the development project. Whether species equality can be achieved by offset design is unknown. We addressed this gap by reviewing derogation files (i.e., specific files that describe mitigation measures to ensure no net loss under the EU Habitats and Birds Directives) from 85 development projects in France (2009–2010). We collected information on type of effect (reversible vs. irreversible) and characteristics of affected and offset sites (i.e., types of species, total area). We analyzed how the type of effect and the affected‐site characteristics influenced the occurrence of offset measures. The proportion of species targeted by offset measures (i.e., offset species) increased with the irreversibility of the effect of development and the conservation status of the species affected by development (i.e., affected species). Not all effects on endangered species (International Union for Conservation of Nature Red List) were offset; on average, 82% of affected species would be offset. Twenty‐six percent of species of least concern were offset species. Thirty‐five percent of development projects considered all affected species in their offset measures. Species richness was much lower in offset sites than in developed sites even after offset proposals. For developed areas where species richness was relatively high before development, species richness at offset sites was 5–10 times lower. The species‐equality principle appears to have been applied only partially in offset policies, as in the EU directives. We suggest the application of this principle through offsets is highly important for the long‐term conservation of biodiversity in Europe. Compensaciones y Conservación de las Especies de las Directivas de Hábitats y Aves de la UE     

Trade-Offs between Species Conservation and the Size of Marine Protected Areas

Abstract:  Moving from single-species- to ecosystem-based management requires an understanding of how community-level attributes such as diversity change with area. We used survey data from bottom trawls to examine spatial patterns of species richness in U.S. Pacific coastal fishes. Specifically, we generated and compared species–area relationships (SARs) for species classified into several groups on the basis of maximum body size, trophic level, diet, maximum depth, geographic affinity, and taxonomic order. Because SARs among groups were not parallel and z values varied significantly for several groups, groups of species were under- or overrepresented (depending on the size of the area) relative to their proportions in the entire community (i.e., entire U.S. Pacific coast). In this way, differences in SARs help demonstrate trade-offs between species representation and coastal area and suggest strategies (such as targeting the protection of habitats and locations where a particular species or groups of species are maximized) that may minimize the size of marine protected areas (MPAs) but protect diversity at the level of the community and functional group.     

Conservation of Species in Dynamic Landscapes: Divergent Fates of Silene tatarica Populations in Riparian Habitats

Abstract:  In transient environments, where local extinctions occur as a result of destruction or deterioration of the local habitat, the long-term persistence of a species requires successful colonizations at new, suitable sites. This kind of habitat tracking should be associated with the asynchronous dynamics of local populations, and it can be especially important for the conservation of rare plant species in riparian habitats. We determined spatiotemporal variation in the demography of the perennial Silene tatarica (L.) Pers. in 15 populations (1998–2003) located in periodically disturbed riparian habitats. The habitats differed according to their morphology (flat shores, slopes) and the amount of bare ground (open, intermediate, closed) along a successional gradient. We used elasticity and life-table response analyses and stochastic simulations to study the variation in population demography. Finite population growth rate was higher in intermediate habitats than in open and closed habitats. In stochastic simulations population size increased in most cases, but four populations were projected to become extinct within 12–70 years. The viability of local populations depended most on the survival and growth of juvenile individuals and on the fecundity of large fertile individuals. On a regional scale, the persistence of this species will require a viable network of local populations as protection against local extinctions caused by natural disturbances and succession. Accordingly, the long-term persistence of riparian species may depend on habitat changes; thus, their conservation requires maintenance of natural disturbance dynamics. Along regulated rivers, management activities such as the creation of open habitats for new colonization should be implemented. Similarly, these activities can be rather general requirements for the conservation of endangered species dependent on transient habitats along successional gradients.     

Genetic Variability in mtDNA of the Silvery Gibbon: Implications for the Conservation of a Critically Endangered Species

Abstract: The silvery gibbon (   Hylobates moloch ), endemic to the island of Java, relies on closed-canopy, lowland evergreen forest for its survival. Because Java has lost over 91% of its original forest, silvery gibbons currently occupy small, isolated forest fragments and are threatened with extinction. To contribute to a comprehensive conservation strategy for this species, we analyzed the mtDNA control region of 31 silvery gibbons representing most remaining populations. Our results suggest the presence of at least two genetically differentiated lineages: a "western" lineage, represented by the largest remaining natural population in Gunung Halimun National Park and a "central" lineage, consisting of smaller, more isolated populations in and around the Gunung Masigit/Simpang/Tilu complex, Gunung Gede/Pangrango, and Gunung Slamet. These two lineages, at a minimum, represent different management units that should, except in the most dire circumstances, be managed separately.     

Natural Die-Offs of Large Mammals: Implications for Conservation

The viability of populations is a central concern of biological conservation. The occurrence of catastrophic die-offs may greatly reduce the long-term viability of populations. Theoretical extinction models and viability analyses require information on the frequency of die-offs and on the distribution of die-off severities. A review of literature identified 96 natural die-offs in large mammal populations, with a die-off being defined as a peak-to-trough decline in estimated population numbers of at least 25%. If such die-offs are common, population viability analyses that ignore them may be overly optimistic. The severities of the natural die-offs of large mammals presented here are not uniformly distributed. There is a relative overabundance of die-offs in the 70–90% range, and an underabundance of die-offs greater than 90%. This may indicate the presence of buffers against population extinction. The reported causes of large mammal die-offs were significantly related to trophic level: herbivore die-offs were more often attributed to starvation, while carnivore die-offs were more often attributed to disease. Populations subject to large-scale phenomena such as drought and severe winters may not be protected from die-offs by population subdivision. On the other hand, populations subject to catastrophic disease epidemics may be protected by subdivision, and threatened by corridors between conservation areas and by translocation efforts.     

Gaining Traction: Retreading the Wheels of Marine Conservation

Abstract:  A number of international treaties address the conservation of marine resources. The declining state of the world's oceans suggests that these treaties are not succeeding and could use improvement. The Convention on International Trade in Endangered Species (CITES) is increasingly embracing the conservation of marine species. We examine the evolution of marine species protection under CITES and illuminate some of the mechanisms used and challenges faced in implementing CITES protection. We found that clarification is needed on when and where CITES applies and how CITES should work with other treaties and institutions. The Society for Conservation Biology (SCB) can contribute to increased effectiveness of CITES for marine conservation. Foremost, the SCB community could foster dialogue on creating a broad vision of how CITES should apply to marine species and how it can synergistically interact with other important marine-conservation treaties and institutions. More specific contributions could focus on defining listing criteria for marine species, improving the science behind the nondetriment finding, and offering technical guidance on species proposals. A future role for SCB could be to contribute to the enhanced effectiveness of other marine conservation agreements such as the Convention on the Conservation of Migratory Species of Wild Animals, the International Whaling Commission, and the United Nations Convention on the Law of the Sea .     

Environmental Dependency of Inbreeding Depression: Implications for Conservation Biology

Inbreeding depression is environmentally dependent, such that a population may suffer from inbreeding depression in one environment but not another. We examined the phenotypic responses of 35 inbred ( F = 0.672) lineages of the red flour beetle Tribolium castaneum in two different climatic environments. We found a significant environmental effect on males but not females. More important, we found that the rank fitness order of lineages differs between environments; lineages of high fitness in one environment may have low fitness in another environment. This change in rank is evident in a significant genotype-by-environment interaction for inbreeding depression for both females and males. These results suggest that even if we know the average environmental effect of inbreeding depression in a population, for any particular lineage measurements of inbreeding depression in one environment may not predict the level of inbreeding depression in another environment. Conservation biologists need to be aware of the environmental dependency of inbreeding depression when planning wildlife refuges or captive propagation programs for small populations. Ideally, captive propagation programs should maintain separate lineages for release efforts. Refuge design programs should consider maintaining a range of habitat types.     

Relationships among Isolated Wetland Size, Hydroperiod, and Amphibian Species Richness: Implications for Wetland Regulations

Abstract: Wetland development within the United States is regulated primarily by size. Decisions concerning wetland destruction or conservation are therefore based in part on three inherent assumptions: (1) small wetlands contain water for short portions of the year; (2) small wetlands support few species; and (3) species found in small wetlands are also found in larger wetlands. We tested these assumptions using data on wetland size, relative hydroperiod (drying scores), and relative species richness of amphibians in depression wetlands of the southeastern United States. We found a significant (p = 0.03) but weak (r² = 0.05) relationship between hydroperiod and wetland size and no relationship (p = 0.48) between amphibian species richness and wetland size. Furthermore, synthetic models of lentic communities predict that short-hydroperiod wetlands support a unique group of species. Empirical investigations support this prediction. Our results indicate that hydroperiod length should be included as a primary criterion in wetland regulations. We advocate a landscape approach to wetlands regulation, focused in part on conserving a diversity of wetlands that represent the entire hydroperiod gradient.