Tropical coastal habitats as surrogates of fish community structure, grazing, and fisheries value

Habitat maps are frequently invoked as surrogates of biodiversity to aid the design of networks of marine reserves. Maps are used to maximize habitat heterogeneity in reserves because this is likely to maximize the number of species protected. However, the technique's efficacy is limited by intra-habitat variability in the species present and their abundances. Although communities are expected to vary among patches of the same habitat, this variability is poorly documented and rarely incorporated into reserve planning. To examine intra-habitat variability in coral-reef fishes, we generated a data set from eight tropical coastal habitats and six islands in the Bahamian archipelago using underwater visual censuses. Firstly, we provide further support for habitat heterogeneity as a surrogate of biodiversity as each predefined habitat type supported a distinct assemblage of fishes. Intra-habitat variability in fish community structure at scales of hundreds of kilometers (among islands) was significant in at least 75% of the habitats studied, depending on whether presence/absence, density, or biomass data were used. Intra-habitat variability was positively correlated with the mean number of species in that habitat when density and biomass data were used. Such relationships provide a proxy for the assessment of intra-habitat variability when detailed quantitative data are scarce. Intra-habitat variability was examined in more detail for one habitat (forereefs visually dominated by Montastraea corals). Variability in community structure among islands was driven by small, demersal families (e.g., territorial pomacentrid and labrid fishes). Finally, we examined the ecological and economic significance of intra-habitat variability in fish assemblages on Montastraea reefs by identifying how this variability affects the composition and abundances of fishes in different functional groups, the key ecosystem process of parrotfish grazing, and the ecosystem service of value of commercially important finfish. There were significant differences in a range of functional groups and grazing, but not fisheries value. Variability at the scale of tens of kilometers (among reefs around an island) was less than that among islands. Caribbean marine reserves should be replicated at scales of hundreds of kilometers, particularly for species-rich habitats, to capture important intra-habitat variability in community structure, function, and an ecosystem process.     

Spatial scaling of avian population dynamics: population abundance, growth rate, and variability

Synchrony in population fluctuations has been identified as an important component of population dynamics. In a previous study, we determined that local-scale (<15-km) spatial synchrony of bird populations in New England was correlated with synchronous fluctuations in lepidopteran larvae abundance and with the North Atlantic Oscillation. Here we address five questions that extend the scope of our earlier study using North American Breeding Bird Survey data. First, do bird populations in eastern North America exhibit spatial synchrony in abundances at scales beyond those we have documented previously? Second, does spatial synchrony depend on what population metric is analyzed (e.g., abundance, growth rate, or variability)? Third, is there geographic concordance in where species exhibit synchrony? Fourth, for those species that exhibit significant geographic concordance, are there landscape and habitat variables that contribute to the observed patterns? Fifth, is spatial synchrony affected by a species' life history traits? Significant spatial synchrony was common and its magnitude was dependent on the population metric analyzed. Twenty-four of 29 species examined exhibited significant synchrony in population abundance: mean local autocorrelation (rho)= 0.15; mean spatial extent (mean distance where rho=0) = 420.7 km. Five of the 29 species exhibited significant synchrony in annual population growth rate (mean local autocorrelation = 0.06, mean distance = 457.8 km). Ten of the 29 species exhibited significant synchrony in population abundance variability (mean local autocorrelation = 0.49, mean distance = 413.8 km). Analyses of landscape structure indicated that habitat variables were infrequent contributors to spatial synchrony. Likewise, we detected no effects of life history traits on synchrony in population abundance or growth rate. However, short-distance migrants exhibited more spatially extensive synchrony in population variability than either year-round residents or long-distance migrants. The dissimilarity of the spatial extent of synchrony across species suggests that most populations are not regulated at similar spatial scales. The spatial scale of the population synchrony patterns we describe is likely larger than the actual scale of population regulation, and in turn, the scale of population regulation is undoubtedly larger than the scale of individual ecological requirements.     

Perceived barriers to and drivers of community participation in protected‐area governance

Protected areas (PAs) are a frequently used conservation strategy, yet their socioeconomic impacts on local communities remain contentious. A shift toward increased participation by local communities in PA governance seeks to deliver benefits for human well‐being and biodiversity. Although participation is considered critical to the success of PAs, few researchers have investigated individuals’ decisions to participate and what this means for how local people experience the costs and benefits of conservation. We explored who participates in PA governance associations and why; the perceived benefits and costs to participation; and how costs and benefits are distributed within and between communities. Methods included 3 focus groups, 37 interviews, and 217 questionnaire surveys conducted in 3 communities and other stakeholders (e.g., employees of a nongovernmental organization and government officials) in PA governance in Madagascar. Our study design was grounded in the theory of planned behavior (TPB), the most commonly applied behavior model in social psychology. Participation in PA governance was limited by miscommunication and lack of knowledge about who could get involved and how. Respondents perceived limited benefits and high costs and uneven distribution of these within and between communities. Men, poorer households, and people in remote villages reported the highest costs. Our findings illustrate challenges related to comanagement of PAs: understanding the heterogeneous nature of communities; ensuring all households are represented in governance participation; understanding differences in the meaning of forest protection; and targeting interventions to reach households most in need to avoid elite capture.     

Lipid biochemistry and reproductive biology in two species of Gammaridae (Crustacea: Amphipoda)

Gammarus oceanicus Segerstråle, 1947 and Echinogammarus marinus (Leach, 1815) were sampled during the breeding season from Oslofjord in 1984, and their lipid composition examined in relation to reproductive condition. In G. oceanicus, female lipid content increased as the ovary matured. Both the amount of lipid stored and the rate of accumulation were greater in spring than in winter. Spring eggs contained 12.4 g lipid, of which 63% was triacylglycerol and 27% phospholipid. Both fractions decreased steadily during embryonic development. Winter eggs contained 19.2g lipid, of which 52% was triacylglycerol and 43% phospholipid. During the early stages of embryonic development the amount of phospholipid decreased sharply, whereas that of triacylglycerol increased, suggesting that some of the fatty acid released from phospholipid was sequestered temporarily as triacylglycerol. When newly spawned, both winter and spring eggs were richer in monoenoic fatty acids than adult amphipods and these acids were the major fuel consumed during development. 6 fatty acids were utilised more slowly than 3 acids, and egg carotenoid pigment content remained constant. Female E. marinus increased in lipid content as the ovary matured. Spring eggs contained 14.7 g lipid when newly spawned and this increased to 16.6 g during the early stages of development. This increase was entirely triacylglycerol, which declined in later stages; the source of the extra lipid was unclear. Eggs contained very little phospholipid or sterol, and both of these components remained at a steady low level during development. E. marinus eggs were not significantly rich in thonoenoic acids compared with adults, and saturated, monoenoic and polyenoic acids were utilised about equally during development. Both adults and eggs were rich in 20.46, which was utilised at a slower rate than the 3 polyunsaturated acids during embryonic development; again, egg carotenoid pigment content remained constant. In both species there was a decrease in the size of the egg (and as a result, of the newly hatched juvenile), but an increase in total reproductive output (i.e., the total weight of the egg clutch) per female as the breeding season proceeded. The reproductive output of an individual female is probably related to food availability during the period of ovarian maturation, whereas the size of an individual egg is dictated largely by feeding conditions for the juveniles once they are independent of the female. The different patterns of lipid utilisation during development found in this study emphasize the flexibility of response in the reproductive biology of gammarid amphipods. It is not yet possible, however, to relate the differing patterns in a simple way either to egg size or total female reproductive output. Two outstanding problems are the source of extra triacylglycerol during the early stages of development of E. marinus and the metabolic cost of brooding eggs.     

Comparative observations on the biometry and development of Calanus finmarchicus and C. helgolandicus in Copepodite Stage V,with comments on other Calanidae

A similar, sexual dimorphism in Copepodite Stage V was observed in winter generations of Calanus finmarchicus (Gunnerus) and C. helgolandicus (Claus), co-existing in the Firth of Clyde, Scotland. In both species, the frequency distribution of prosome length in the Copepodite V population was bimodal. Among individual Stage V copepodites kept in the laboratory, those of the larger form alone produced adult males. Indications of morphological distinctions between the forms other than in size, however, were absent. Differences in least-squares regressions of individual cephalosome on metasome lengths, previously attributed to a distinction in prosome shape by Grigg et al. (1985), reflected size alone. These two measurements also were greater in the “large” form, but this independently of each other. Variations in their relative contributions to the prosome length distinguished individuals, and were continuous between the forms. Present and previously published observations on members of the family Calanidae have been compared. The presence, or not, of a sexual distinction in prosome length in the Stage V copepodite is variable among calanids, within and between species. A possible association with the extent of seasonal variations in size and life-cycle characteristics is suggested.     

Age-specific social dominance affects habitat use by breeding American redstarts (Setophaga ruticilla): a removal experiment

Summary By removing older males from their breeding territories, we tested the hypothesis that age-related dominance behavior influenced the pattern of habitat selection by breeding American redstarts Setophaga ruticilla (Aves: Parulinae). Fifteen older male redstarts removed in five experimental replicates during three breeding seasons were replaced by ten yearling and five older males; no redstart males of either age colonized the control sites during the same time periods, although two yearlings disappeared. Significantly more yearling males (67%, n=9) colonized the vacated areas than were present in the redstart population at large (26.8%, n=209). We reject the alternative hypothesis that yearling male redstarts occupy different habitats from older males because of age-related (innate) habitat preferences. Redstarts that colonized the territories made vacant by our removals (i.e., floaters) were a behaviorally heterogeneous group of animals. The presence of both yearling and older male floaters indicates that suitable habitat is limiting for this species and that intraspecific competitive interactions are important in habitat distribution, and potentially in population regulation.     

BENEFITS OF ITERATIVE WATER SUPPLY FORECASTING IN THE WASHINGTON,D.C., METROPOLITAN AREA1

The three largest water utilities in the Washington, D.C., metropolitan area (WMA) rely on the Potomac River and its reservoirs for water supply. These utilities have committed to a periodic review of the system's adequacy to meet future demands. In 1990, 1995, 2000, and again in 2004 (for publication in 2005) the utilities requested that the Interstate Commission on the Potomac River Basin (ICPRB) conduct a 20‐year water demand and resource adequacy study to fulfill this need. The selection of the five‐year interval provides multiple benefits. It allows regular updates and incorporation of recent demographic forecasts, and it increases visibility and understanding of the adequacy of the region's water resources. It also provides adequate time to conduct research on the physical system and to incorporate modifications based on this research into subsequent studies. The studies and lessons learned are presented in this case study of the WMA. The work has been a natural outgrowth of a long history of cooperative water supply planning and management among the main WMA water utilities and ICPRB.     

Using three-dimensional surface area to compare the growth of two Pocilloporid coral species

Many facets of coral research require coral colony surface area estimates. This study developed a relationship between the two-dimensional (2D) projected area and the three-dimensional (3D) whole colony surface area for two commonly studied Indo-Pacific coral species: Pocillopora damicornis and Stylophora pistillata. The surface index function was used to measure the growth of colonies in situ around Heron reef on the southern Great Barrier Reef. The results show that while growth between the two species was not significantly different when measured in two dimensions, the 3D area showed significantly different growth rates with S. pistillata growing at almost double the rate of P. damicornis. The study demonstrates that it is possible to make reliable estimates of the 3D surface area of entire colonies of these complex branching coral species, using the plan view of the coral and a pre-determined surface index function. In addition, this study shows that the 3D surface area provides a more useful measure of colony growth than the traditional methods of either 2D area or longest dimension.     

Detecting Extinction Risk from Climate Change by IUCN Red List Criteria

Anthropogenic climate change is a key threat to global biodiversity. To inform strategic actions aimed at conserving biodiversity as climate changes, conservation planners need early warning of the risks faced by different species. The IUCN Red List criteria for threatened species are widely acknowledged as useful risk assessment tools for informing conservation under constraints imposed by limited data. However, doubts have been expressed about the ability of the criteria to detect risks imposed by potentially slow‐acting threats such as climate change, particularly because criteria addressing rates of population decline are assessed over time scales as short as 10 years. We used spatially explicit stochastic population models and dynamic species distribution models projected to future climates to determine how long before extinction a species would become eligible for listing as threatened based on the IUCN Red List criteria. We focused on a short‐lived frog species (Assa darlingtoni) chosen specifically to represent potential weaknesses in the criteria to allow detailed consideration of the analytical issues and to develop an approach for wider application. The criteria were more sensitive to climate change than previously anticipated; lead times between initial listing in a threatened category and predicted extinction varied from 40 to 80 years, depending on data availability. We attributed this sensitivity primarily to the ensemble properties of the criteria that assess contrasting symptoms of extinction risk. Nevertheless, we recommend the robustness of the criteria warrants further investigation across species with contrasting life histories and patterns of decline. The adequacy of these lead times for early warning depends on practicalities of environmental policy and management, bureaucratic or political inertia, and the anticipated species response times to management actions. Detección del Riesgo de Extinción a partir del Cambio Climático por medio del Criterio de la Lista Roja de la UICNKeith et al.     

Benefits to poorly studied taxa of conservation of bird and mammal diversity on islands

Protected area delineation and conservation action are urgently needed on marine islands, but the potential biodiversity benefits of these activities can be difficult to assess due to lack of species diversity information for lesser known taxa. We used linear mixed effects modeling and simple spatial analyses to investigate whether conservation activities based on the diversity of well‐known insular taxa (birds and mammals) are likely to also capture the diversity of lesser known taxa (reptiles, amphibians, vascular land plants, ants, land snails, butterflies, and tenebrionid beetles). We assembled total, threatened, and endemic diversity data for both well‐known and lesser known taxa and combined these with physical island biogeography characteristics for 1190 islands from 109 archipelagos. Among physical island biogeography factors, island area was the best indicator of diversity of both well‐known and little‐known taxa. Among taxonomic factors, total mammal species richness was the best indicator of total diversity of lesser known taxa, and the combination of threatened mammal and threatened bird diversity was the best indicator of lesser known endemic richness. The results of other intertaxon diversity comparisons were highly variable, however. Based on our results, we suggest that protecting islands above a certain minimum threshold area may be the most efficient use of conservation resources. For example, using our island database, if the threshold were set at 10 km² and the smallest 10% of islands greater than this threshold were protected, 119 islands would be protected. The islands would range in size from 10 to 29 km² and would include 268 lesser known species endemic to a single island, along with 11 bird and mammal species endemic to a single island. Our results suggest that for islands of equivalent size, prioritization based on total or threatened bird and mammal diversity may also capture opportunities to protect lesser known species endemic to islands. Beneficios de los Taxa Poco Estudiados para la Conservación de la Diversidad de Aves y Mamíferos en Islas