Testing the utility of abiotic surrogates for marine habitat mapping at scales relevant to management

Habitat mapping at the scale at which marine protected areas are designed and managed is essential for assessment of, and design for, representation. Most habitat mapping studies rely solely or in part on abiotic surrogates for patterns of biodiversity. The utility of abiotic variables in predicting biological distributions at the local scale (10 s of km) was tested in a remote video survey of macrobenthos in Moreton Bay, Australia. Habitat classifications of the same set of 41 sites based on 6 abiotic variables and abundances of 89 taxa and bioturbation indicators were compared using correlation, regression and ordination analyses. The concepts of false homogeneity (abiotically similar but biologically distinct) and false heterogeneity (abiotically distinct but biologically similar) were defined to describe types of errors associated with using abiotic surrogates to construct habitat maps, and quantified using two separate methods. Overall, the best prediction by abiotic surrogates explained less than 30% of the pattern of biological similarity. Errors of false homogeneity were between 20% and 62%, depending on the methods of estimation. Predictive capability of abiotic surrogates at the taxon level was poor, with only 6% of taxon/surrogate correlations significant. Abiotic variables did not discriminate sufficiently between different soft bottom communities to be a reliable basis for mapping. These results have implications for the widespread use of abiotic surrogates in marine habitat mapping to plan for, or assess, representation in marine protected areas. Little confidence can be placed in marine habitat classifications based solely or largely on abiotic surrogates without calibration by rigorous biological surveys at the appropriate scale. Therefore, it is questionable whether marine protected areas designed on this basis can have measurable benefits for conservation.     

Effects of fishing and protection on Brazilian reef fishes

The vast Brazilian coast harbors unique and diverse reef fish communities. Unfortunately, relatively little is known about the impact of fishing on these fish species, and few management or conservation efforts are being made to protect them. Here, we examine the effect of different levels of protection on the composition, abundance, and size structure of reef fish species along a 2500 km portion of the Brazilian coastline, noting in particular the relative abundance of endemics and the effect of protection on these species. Pairwise comparisons of sites with different protection status (more versus less protected) were used to determine the potential responses of reef fishes to the establishment of marine protected areas. Highly targeted species (top predators and large herbivores) were significantly more abundant and larger in size within sites with a higher degree of protection, indicating that they benefit from protection, while lightly fished and unfished species were not. These results are consistent with past work documenting the responses of species to protection. Here, we use our results in particular to suggest strategies and provide expectations for managing and protecting Brazilian reef fisheries. Because this biogeographic province lies entirely within the jurisdiction of a single nation, there may be unique and significant opportunities to effectively manage and conserve these fish species.     

Woody species diversity in temperate Andean forests: The need for new conservation strategies

Chile has more than half of the temperate forests in the southern hemisphere. These have been included among the most threatened eco-regions in the world, because of the high degree of endemism and presence of monotypic genera. In this study, we develop empirical models to investigate present and future spatial patterns of woody species richness in temperate forests in south-central Chile. Our aims are both to increase understanding of species richness patterns in such forests and to develop recommendations for forest conservation strategies. Our data were obtained at multiple spatial scales, including field sampling, climate, elevation and topography data, and land-cover and spectrally derived variables from satellite sensor imagery. Climatic and land-cover variables most effectively accounted for tree species richness variability, while only weak relationships were found between explanatory variables and shrub species richness. The best models were used to obtain prediction maps of tree species richness for 2050, using data from the Hadley Centre’s HadCM3 model. Current protected areas are located far from the areas of highest tree conservation value and our models suggest this trend will continue. We therefore suggest that current conservation strategies are insufficient, a trend likely to be repeated across many other areas. We propose the current network of protected areas should be increased, prioritizing sites of both current and future importance to increase the effectiveness of the national protected areas system. In this way, target sites for conservation can also be chosen to bring other benefits, such as improved water supply to populated areas.     

Evaluating ecological integrity in national parks: Case studies from Canada and South Africa

Many existing parks are currently experiencing difficulties in achieving their conservation aims, yet they remain an important option for maintaining and enhancing the conservation of biological diversity and ecosystem processes. Critics have claimed that many national parks cannot continue to protect the biological resources within their borders, and the sustainability of these areas over the long-term is in question. Ways need to be found to strengthen those that are failing, and to understand and replicate those that are succeeding. This paper presents the empirical results from a systematic evaluation of how effectively six case study national parks and national park reserves in Canada and South Africa have been protecting ecological integrity. Several parks were effective at addressing the priorities for which they had monitoring data, however the effectiveness rating of each park decreased when all indicators, including those identified as priorities but lacking monitoring data, were analysed. This indicates that the parks had generally identified more priority indicators than they were actually able to address (for many reasons, including lack of budget or trained staff, managerial challenges). Overall, a systematic approach to evaluating ecological integrity in national parks is recommended as the managers of protected areas cannot be expected to conserve the biological diversity and ecosystem processes within their borders if they are unaware of the ecological status of the park’s biodiversity. The paper concludes with several practical recommendations for monitoring ecological integrity in national parks.     

Controls over pathways of carbon efflux from soils along climate and black spruce productivity gradients in interior Alaska

Small changes in C cycling in boreal forests can change the sign of their C balance, so it is important to gain an understanding of the factors controlling small exports like water-soluble organic carbon (WSOC) fluxes from the soils in these systems. To examine this, we estimated WSOC fluxes based on measured concentrations along four replicate gradients in upland black spruce (Picea mariana [Mill.] BSP) productivity and soil temperature in interior Alaska and compared them to concurrent rates of soil CO₂ efflux. Concentrations of WSOC in organic and mineral horizons ranged from 4.9 to 22.7 g C m⁻² and from 1.4 to 8.4 g C m⁻², respectively. Annual WSOC fluxes (4.5-12.0 g C m⁻² y⁻¹) increased with annual soil CO₂ effluxes (365-739 g C m⁻² y⁻¹) across all sites (R²=0.55, p=0.02), with higher fluxes occurring in warmer, more productive stands. Although annual WSOC flux was relatively small compared to total soil CO₂ efflux across all sites (<3%), its relative contribution was highest in warmer, more productive stands which harbored less soil organic carbon. The proportions of relatively bioavailable organic fractions (hydrophilic organic matter and low molecular weight acids) were highest in WSOC in colder, low-productivity stands whereas the more degraded products of microbial activity (fulvic acids) were highest in warmer, more productive stands. These data suggest that WSOC mineralization may be a mechanism for increased soil C loss if the climate warms and therefore should be accounted for in order to accurately determine the sensitivity of boreal soil organic C balance to climate change.     

Beyond parks as monoliths: Spatially differentiating park-people relationships in the Tadoba Andhari Tiger Reserve in India

Parks represent spatially and socially heterogeneous conservation units, yet are often assessed and managed using spatially homogeneous approaches. This paper represents an effort to focus on the larger social-ecological landscapes within which protected areas are embedded, to understand why conservation succeeds and fails in different parts of the landscape. In a wildlife sanctuary in the central plains of India (Tadoba Andhari Tiger Reserve), we address: (i) how people living within and immediately outside a park differentially impact its resources and (ii) how the park differentially impacts communities living within. Using forest plots, satellite imagery and interviews, we evaluate park conservation by assessing plant diversity, land cover change, forest fragmentation, and attitudes of local communities towards conservation. We find that interior villages have a negative impact on regeneration, but there is a decline in tree species diversity, and increased forest cover change and fragmentation at the park periphery. Interior villages suffer greatly from crop and livestock depredations by wildlife and consider park rules to be unfairly devised. Yet, they affirm the importance of the park for conservation, and are willing to work with park authorities for stricter protection. Park authorities largely focus on resettlement of interior villages, when they should also pay attention to protecting the peripheral areas of the park from severe degradation by surrounding villages. In summary, we find that different parts of the park landscape face different conservation challenges. Taking into account spatial variations in the factors influencing conservation can greatly benefit the management of protected areas.     

Are higher taxa adequate surrogates for species-level assemblage patterns and species richness in stream organisms?

We examined the utility of using genera and families as surrogates of species-level assemblage patterns. We assessed cross-taxonomic level congruence, as well as taxonomic structure-environment and taxon richness-environment relationships in stream macroinvertebrate and diatom data surveyed across Finland. A number of interesting and important findings emerged from our analyses. For both macroinvertebrates and diatoms, species richness was strongly correlated with genus and family richness, and similarities in assemblage structure between species-, genus- and family-level matrices were also significant and relatively strong. For macroinvertebrates, the key environmental variables for assemblage structure and taxon richness remained the same irrespective of taxonomic level. For diatoms, however, the environmental variables related to variation in diatom taxon richness varied between taxonomic data sets, while determinants of assemblage structure remained largely the same. For macroinvertebrates, relatively similar amounts of variation in assemblage structure and taxon richness for species-, genus-, and family-level data were accounted for by the environmental variables, shared environmental and spatial variables, spatial variables, and total variation explained. By contrast, for diatoms, these components of variability differed somewhat between taxonomic levels. Our results suggest that, for macroinvertebrates, even family-level data could be used in rapid biodiversity assessments, where the objective is to examine biodiversity patterns and rank sites according to their conservation value in our study region. Families might also perform well in this task in other regions that are characterized by low faunal species diversity, but the situation is likely to be different for regions with higher species diversity. Although weaker than the relationships in macroinvertebrate data, species-level data for diatoms also showed rather similar patterns to genus- and family-level data. However, due to the low number of diatom families, it is likely that families do not provide enough variability in biodiversity patterns. Thus, for diatoms, genus-level data could perhaps be more efficient than family-level data in correlating with species-level data and portraying assemblage patterns for conservation purposes.     

Lakeshore diversity and rarity relationships along interacting disturbance gradients: catchment area, wave action and depth

Diversity patterns of riparian plant communities have been associated with disturbance. Populations of a diversity of Atlantic Coastal Plain plants occur as disjuncts on shores of large catchment area lakes in Nova Scotia. These lakeshore communities contain rare plants with local, national and global rankings. The populations of rare plants are dynamic and their management requires an understanding of the relationship between disturbance and the survival of rare plants. This present study measured (overwinter wooden dowel removal) and observed disturbance along gradients of catchment area (CA), exposure and depth. In three separate experiments ranging from the landscape to the lake, to the single shoreline level, disturbance was linked to lake CA, exposure and depth, respectively. At all scales, disturbance was positively associated with the presence of rare species. The pattern of rare species richness over the river system was complex; at the within-lake level, the frequency of rare species per site was greatest in the intermediate CA lake while the pool of rare species was greatest in the largest CA lake. The findings focus field efforts on wide, exposed shorelines of large CA lakes where new rare plants continue to be discovered. In addition, the discrepancy between highest frequency of rare plants on intermediate CA lakes and highest species pools of rarities on large CA lakes, reinforces the need for larger protected area systems for the most naturally disturbed ecosystems which often support populations having a high turnover rate but a low site to site frequency.     

Incorporating anthropogenic threats into evaluations of regional biodiversity and prioritisation of conservation areas in the Limpopo Province, South Africa

Recent attempts to streamline the identification of areas requiring immediate conservation attention have resulted in the development of prioritisation procedures that identify areas of biodiversity importance facing large threats in the near future. This study incorporated biodiversity data on bird and vegetation distribution with an assessment of land use suitability for cultivation and afforestation for the Limpopo Province of South Africa. The low altitude savanna regions in the northeast contain high species diversity, but are unsuitable to alternative forms of land use and are well conserved (by e.g., the Kruger National Park). The central and eastern mountain ranges, sites of high biodiversity, are suitable to dryland cultivation and afforestation and are thus potential conservation priorities. Areas with high biodiversity values, e.g., irreplaceable areas that contain biodiversity features essential for meeting conservation targets, were then investigated for their potential land-use threats in order to prioritise those needing immediate conservation actions. We suggest how losses of biodiversity could be minimised by reaching such decisions more quickly.     

The feeding habits of collembola along decomposition gradients using stable carbon and nitrogen isotope analyses

We measured the natural stable carbon (C) and nitrogen (N) isotope ratio patterns of collembola and the organic substrates of their habitats and potential food sources in a warm temperate coniferous forest. Based on previous studies, we classified collembola into successional classes along litter decomposition gradients: early colonizers, late colonizers, and dominants-throughout. The stable C and N isotope ratios of late colonizers exceeded those of early colonizers, and those of the dominants-throughout were intermediate between early and late colonizers, which is consistent with previous studies on two macro-invertebrates, earthworms and termites. The C and N isotopic signature differences in collembola may reflect food resource partitioning along decomposition gradients.     

The cost of postponing biodiversity conservation in Mexico

Though Neotropical countries are the most species rich in the world, their biodiversity is threatened by the loss of native vegetation. Land conversion in Mexico during the last 30 years has been extensive and is representative of that of other developing countries. However, the effects of land use change on the required size and configuration of an adequate biological conservation area network are largely unknown. It is shown here that endemic mammals in Mexico could have been protected considerably more economically if a conservation plan had been implemented in 1970 than is possible today due to extensive conversion of primary habitats. Analysis of the distributions of 86 endemic mammal species in 1970, 1976, 1993, and 2000 indicates that the distributions of 90% of the species shrank during this 30-year period. At each time step, optimal conservation area networks were selected to represent all species. 90% more land must be protected after 2000 to protect adequate mammal habitat than would have been required in 1970. In addition, under a realistic conservation budget, 79% fewer species can be represented adequately in a conservation area network after 2000 compared to 1970. This provides an incentive for rapid conservation action in Mexico and other biodiversity hotspots with comparable deforestation rates, including Burma, Ecuador, Indonesia, the Philippines, and Sri Lanka. Due to ongoing habitat degradation, the efficiency of a conservation plan decreases with delays in its implementation.     

Conservation planning with dynamic threats: The role of spatial design and priority setting for species’ persistence

Conservation actions frequently need to be scheduled because both funding and implementation capacity are limited. Two approaches to scheduling are possible. Maximizing gain (MaxGain) which attempts to maximize representation with protected areas, or minimizing loss (MinLoss) which attempts to minimize total loss both inside and outside protected areas. Conservation planners also choose between setting priorities based solely on biodiversity pattern and considering surrogates for biodiversity processes such as connectivity. We address both biodiversity processes and habitat loss in a scheduling framework by comparing four different prioritization strategies defined by MaxGain and MinLoss applied to biodiversity patterns and processes to solve the dynamic area selection problem with variable area cost. We compared each strategy by estimating predicted species’ occurrences within a landscape after 20 years of incremental reservation and loss of habitat. By incorporating species-specific responses to fragmentation, we found that you could improve the performance of conservation strategies. MinLoss was the best approach for conserving both biodiversity pattern and process. However, due to the spatial autocorrelation of habitat loss, reserves selected with this approach tended to become more isolated through time; losing up to 40% of occurrences of edge-sensitive species. Additionally, because of the positive correlation between threats and land cost, reserve networks designed with this approach contained smaller and fewer reserves compared with networks designed with a MaxGain approach. We suggest a possible way to account for the negative effect of fragmentation by considering both local and neighbourhood vulnerability to habitat loss.     

Patterns of nonindigenous herpetofaunal richness and biotic homogenization among Florida counties

Recent studies of geographic patterns of nonindigenous species richness suggest that a few key biogeographic and anthropogenic factors explain much of the variation in the richness of established species. It remains unknown, however, if the factors identified in these studies are taxon- and scale-specific or if general rules apply broadly across taxa and spatial scales. To address this issue, I used multiple regression analysis to identify factors that contribute significantly to variation in nonindigenous herpetofaunal richness at a relatively small spatial scale, the county level, in Florida, USA. Additionally, I used the Jaccard similarity index to determine if nonindigenous species affect the biotic similarity of the herpetofaunas of Floridian counties. In the regression analysis, county latitude strongly and negatively affected nonindigenous herpetofaunal richness, explaining approximately two-thirds of the variation in this variable. To a smaller degree, human population and university presence both related positively with nonindigenous herpetofaunal richness. Several other variables, including county land area, were not significantly related to nonindigenous herpetofaunal richness. The consistent importance of human population to nonindigenous species richness in this and past studies suggests that the influence of anthropogenic factors may be universal and are as or more important than the natural biogeographic factors that generally relate with native species richness. No evidence of overall homogenization was found based on Jaccard index values. However, a significant relationship between homogenization scores and distance between counties suggests that the effect of nonindigenous herpetofaunal richness on the similarity of county biotas is scale-dependent, such that adjacent counties tend to experience homogenization, while distant counties tend to experience differentiation as a result of the presence of nonindigenous herpetofauna. The results of this and similar studies may be useful in predicting the introduction and spread of nonindigenous species and in evaluating the effects of such introductions on native biodiversity.     

The biological importance of the Eastern Arc Mountains of Tanzania and Kenya

The Eastern Arc Mountains are renown in Africa for high concentrations of endemic species of animals and plants. Thirteen separate mountain blocks comprise the Eastern Arc, supporting around 3300 km² of sub-montane, montane and upper montane forest, less than 30% of the estimated original forested area. At least 96 vertebrate species are endemic, split as follows: 10 mammal, 19 bird, 29 reptile and 38 amphibian species. This includes four endemic or nearly endemic species of primate - the Sanje Mangabey, the Iringa Red Colobus, the Mountain Galago and the new Kipunji monkey that forms its own monotypic genus. A further 71 vertebrate species are near-endemic. At least 800 vascular plant species are endemic, almost 10% of these being trees. These endemics include the majority of the species of African violet - Saintpaulia, a well-known flowering plant in Western households. An additional 32 species of bryophytes are also endemic. Many hundreds of invertebrates are also likely to be endemic, with data for butterflies, millipedes and dragonflies indicating potential trends in importance. Seventy-one of the endemic or near-endemic vertebrates are threatened by extinction (8 critical, 27 endangered, 36 vulnerable), with an additional seven wide ranging threatened species. Hundreds of plant species are also threatened. Most Eastern Arc endemics are closed-forest specialists and comprise taxa with an ancient history and those of more recent origin, including some possessing ancient affinities with taxa from West Africa, Madagascar, and even South America and Southeast Asia. Mountain block prioritisation for biodiversity conservation shows that Udzungwas, East Usambaras and Ulugurus are the most important blocks, with other important blocks being the Ngurus and West Usambaras. Rankings are correlated closely with the area of remaining forest. Most of the remaining forest is found within nearly 150 Government Forest Reserves, with 106 of these managed nationally for water catchment, biodiversity and soil conservation and where forest exploitation is not allowed. Outside these areas most forest has been cleared, except in small village burial/sacred sites, a few Village Forest Reserves, and inaccessible areas. In most Eastern Arc Mountains the local populations have not encroached beyond the reserve boundaries to develop farms, but forest resources within the boundaries are used for fuel and building materials and some forests are heavily degraded. Fire is also a problem as it enters and destroys forests during the dry seasons. The future of the biodiversity on the Eastern Arc Mountains is closely tied to management policies and capacity of the Tanzania Forestry and Beekeeping Division, Tanzania National Parks Authority, and Kenya Forest Department. Supporting these agencies in their mandated job is an essential conservation investment over the longer term.     

Farmland birds and resource protection in the UK: Cross-cutting solutions for multi-functional farming?

Farmland bird declines in Europe are well documented. In the UK, agri-environment schemes are key mechanisms for reversing the declines of birds and other farmland biodiversity, but recent reviews suggest that wet habitats might be a gap in provision by these schemes. Important resources provided by wet habitats include: (i) damp soil, for probing species; (ii) permanent water to provide water-dependent invertebrates, as a source of food; (iii) bare or sparsely vegetated ground in the draw-down zone, to improve access to food; (iv) rank emergent vegetation for nesting. However, wet habitats have been lost from farmland as a result of loss of ponds and filling of ditches, as well as the effective removal of water from fields by surface run-off, itself affected by soil compaction, and extensive under-field drainage. The efficient removal of water from fields can cause problems downstream, both through flooding, and diffuse pollution. Regular farmland pollutants include pesticides, nitrogen, phosphorus and sediment, leading to environmental problems such as eutrophication and reduced quality of drinking water. Major new political instruments, such as the Water Framework Directive, will aim to reduce the impact of this diffuse pollution from agriculture. A variety of solutions to diffuse pollution, such as conservation tillage, buffer strips at field edges, and small constructed wetlands, could simultaneously provide some of the resources required by farmland birds. We suggest that future agri-environment schemes, to be truly multifunctional, could focus on bringing these diverse objectives together.     

Abundance, diversity and connectance of soil food web channels along environmental gradients in an agricultural landscape

Soil food webs respond to anthropogenic and natural environmental variables and gradients. We studied abundance, connectance (a measure of the trophic interactions within each channel), and diversity in three different channels of the soil food web, each comprised of a resource-consumer pair: the microbivore channel (microbes and their nematode grazers), the plant–herbivore channel (plants and plant-feeding nematodes), and the predator–prey channel (predatory nematodes and their nematode prey), and their associations with different gradients in a heterogeneous agricultural landscape that consisted of intensive row crop agriculture and grazed non-irrigated grasslands in central California. Samples were taken at three positions in relation to water channels: water’s edge, bench above waterway, and the adjacent arable or grazed field. Nematode communities, phospholipid fatty acid (PLFA) biomarkers, and soil properties (NH₄⁺-N, NO₃⁻-N, total N, total C, pH, P, bulk density and soil texture) were measured, and riparian health ratings were scored. Environmental variables were obtained from publicly-available data sources (slope, elevation, available water capacity, erodability, hydraulic conductivity, exchangeable cation capacity, organic matter, clay and sand content and pH).The abundance and richness in most food web components were higher in grazed grasslands than in intensive agricultural fields. Consumers contributed less than their resources to the abundance and richness of the community in all channels. The association between richness and abundance for each component was strongest for the lowest trophic links (microbes, as inferred by PLFA) and weakest for the highest (predatory nematodes). The trophic interactions for the predator–prey and plant–herbivore channels were greater in the grassland than in the cropland. Fields for crops or grazing supported more interactions than the water’s edge in the plant–herbivore and microbivore channels. Connectance increased with the total richness of each community. Higher connectance within the microbivore and predator–prey soil food web channels were associated with soil NO₃⁻-N and elevation respectively, which served as surrogate indicators of high and low agricultural intensification.     

Abundance,diversity and connectance of soil food web channels along environmental gradients in an agricultural landscape

Soil food webs respond to anthropogenic and natural environmental variables and gradients. We studied abundance, connectance (a measure of the trophic interactions within each channel), and diversity in three different channels of the soil food web, each comprised of a resource-consumer pair: the microbivore channel (microbes and their nematode grazers), the plant–herbivore channel (plants and plant-feeding nematodes), and the predator–prey channel (predatory nematodes and their nematode prey), and their associations with different gradients in a heterogeneous agricultural landscape that consisted of intensive row crop agriculture and grazed non-irrigated grasslands in central California. Samples were taken at three positions in relation to water channels: water’s edge, bench above waterway, and the adjacent arable or grazed field. Nematode communities, phospholipid fatty acid (PLFA) biomarkers, and soil properties (NH₄⁺-N, NO₃⁻-N, total N, total C, pH, P, bulk density and soil texture) were measured, and riparian health ratings were scored. Environmental variables were obtained from publicly-available data sources (slope, elevation, available water capacity, erodability, hydraulic conductivity, exchangeable cation capacity, organic matter, clay and sand content and pH).The abundance and richness in most food web components were higher in grazed grasslands than in intensive agricultural fields. Consumers contributed less than their resources to the abundance and richness of the community in all channels. The association between richness and abundance for each component was strongest for the lowest trophic links (microbes, as inferred by PLFA) and weakest for the highest (predatory nematodes). The trophic interactions for the predator–prey and plant–herbivore channels were greater in the grassland than in the cropland. Fields for crops or grazing supported more interactions than the water’s edge in the plant–herbivore and microbivore channels. Connectance increased with the total richness of each community. Higher connectance within the microbivore and predator–prey soil food web channels were associated with soil NO₃⁻-N and elevation respectively, which served as surrogate indicators of high and low agricultural intensification.     

Community-based conservation results in the recovery of reef fish spawning aggregations in the Coral Triangle

In the Coral Triangle community-based marine protected areas (MPAs) are being established at a prolific rate. Their establishment can benefit both fisheries and biodiversity, and they provide both a socially and economically acceptable means of managing coral reefs in developing nations. However, because such MPAs are typically small (usually <0.5 km²), they will rarely provide protection to large mobile fishes. An exception to this limitation may exist when community-based MPAs are established to protect small sites where vital processes occur, such as fish spawning aggregations (FSAs). To test the effectiveness of small (0.1–0.2 km²) MPAs for protecting FSAs, we monitored three FSA sites where brown-marbled grouper (Epinephelus fuscoguttatus), camouflage grouper (Epinephelus polyphekadion) and squaretail coralgrouper (Plectropomus areolatus) aggregate to spawn. Sites were monitored during peak reproductive periods (several days prior to each new moon) between January 2005 and November 2009. All three sites are located in New Ireland Province, Papua New Guinea, and had been exploited for decades, but in 2004 two sites were protected by the establishment of community-based MPAs. The third site continued to be exploited. Over the monitoring period densities of E. fuscoguttatus and E. polyphekadion increased at both MPAs, but not at the site that remained open to fishing. At one MPA the densities of E. polyphekadion increased tenfold. Our findings demonstrate that community-based MPAs that are appropriately designed and adequately enforced can lead to the recovery of populations of vulnerable species that aggregate to spawn.     

The responses of leaf litter invertebrates to environmental gradients along road edges in subtropical island forests

Knowledge of how roads affect forest biodiversity can be improved by measuring the responses of indicator species to complex environmental gradients caused by these infrastructures. We studied litter invertebrate species responses to road edges in laurel and pine forests in Tenerife, Canary Islands. We sampled invertebrates from litter and assessed the environmental variation related to road proximity. We also assessed the effect of relevant environmental predictors on a diverse array of potential indicator species. We applied canonical ordination and non-parametric regression (Lowess) to classify invertebrate species responses to roads and their associated gradients. Three types of responses to road edge proximity were defined for the most common invertebrate taxa: edge-preferring or edge specialists, interior-preferring or edge-avoiders, and edge-indifferent or neutral species. Those species appearing most frequently and with higher population density between 1 and 20 m from the edge (commonly peaking at 10 m from the road) were categorized as edge-preferring. We classified taxa attaining peak population densities at or beyond 60 m from the edge (and most commonly 100 m) as interior species. Edge-neutral species were those without an evident pattern of stabilization in abundance along the gradient and with peaks in abundance at varying distance intervals. These edge litter communities contain a high native and endemic diversity but also a significant density of alien fauna. The specific patterns of penetration of road edge effects on invertebrate species should be seen as having a pervasive and cumulative impact considering the exceptionally large number of roads in these forests and the high population densities of alien invertebrates. Future management plans for forest conservation on the Canary Islands should include the highly altered but valuable litter communities along road edges.     

Patterns of solanidine glycoalkaloid variation in four gene pools of the cultivated potato

Patterns of variation for the solanidine-based glycoalkaloids have been determined for tuber material of genebank accessions of landraces of the cultivated potato and three closely-related wild species. Total levels were low in the cultivated taxa investigated,S. phureja, S. stenotomum, and the tetraploidS. tuberosum in its two formsS. tuberosum ssp.tuberosum andS. tuberosum ssp.andigena. The only solanidine-based glycolkaloids found in the tubers investigated in this study were-solanine and-chaconine, with one additional related compound, dehydrocommersonine, found in tubers of an accession ofS. canasense. The ratio of chaconine : solanine differed markedly from a mean of 0.98 inS. phureja to 2.28 in ChileanS. tuberosum ssp.tuberosum. The chaconine : solanine ratio was relatively constant within these two taxa, reflecting their relatively narrow genetic bases, but was much more variable within the taxa regarded as ancestral,S. stenotomum andS. tuberosum ssp.andigena. The wild speciesS. sparsipilum has been implicated in the origin of the tetraploid potato,S. tuberosum, but there was no support for this from the patterns of variation in chaconine : solanine ratio. The cline of chaconine : solanine ratios in cultivated potatoes along the spine of S. America does not appear to relate to the influence of local wild species through introgression, but may instead reflect differing selective pressures acting in different parts of the native range of the cultivated potato.