Edge effects on trophic cascades in tropical rainforests

The cascading effects of biodiversity loss on ecosystem functioning of forests have become more apparent. However, how edge effects shape these processes has yet to be established. We assessed how edge effects alter arthropod populations and the strength of any resultant trophic cascades on herbivory rate in tropical forests of Brazil. We established 7 paired forest edge and interior sites. Each site had a vertebrate-exclosure, procedural (exclosure framework with open walls), and control plot (total 42 plots). Forest patches were surrounded by pasture. Understory arthropods and leaf damage were sampled every 4 weeks for 11 months. We used path analysis to determine the strength of trophic cascades in the interior and edge sites. In forest interior exclosures, abundance of predaceous and herbivorous arthropods increased by 326% and 180%, respectively, compared with control plots, and there were significant cascading effects on herbivory. Edge-dwelling invertebrates responded weakly to exclusion and there was no evidence of trophic cascade. Our results suggest that the vertebrate community at forest edges controls invertebrate densities to a lesser extent than it does in the interior. Edge areas can support vertebrate communities with a smaller contingent of insectivores. This allows arthropods to flourish and indirectly accounts for higher levels of plant damage at these sites. Increased herbivory rates may have important consequences for floristic community composition and primary productivity, as well as cascading effects on nutrient cycling. By interspersing natural forest patches with agroforests, instead of pasture, abiotic edge effects can be softened and prevented from penetrating deep into the forest. This would ensure a greater proportion of forest remains habitable for sensitive species and could help retain ecosystem functions in edge zones.     

The demarcation of arbitrary boundaries for coastal zone management: The Israeli case

Integrated coastal zone management (ICZM) addresses the interconnections, complexities, and conflicts between many users of the coastal area with different goals. It requires setting managerial boundaries that capture many elements of human and natural systems. Experience teaches us that without a directed effort managerial rules and laws are not likely to coincide with the physical sensitivity of units that reflect different environmental characteristics of the coastal zone. Hence the aim of this study is to explore why coastal managerial boundaries are set arbitrarily and whether and how it is possible to address the problems this poses. We examine what influences the decisions of a new coastal management authority in Israel to determine how this body overcomes the limits of arbitrary boundary demarcation. The study found that real life management succeeded to both address areas outside the arbitrary boundaries and also to respect some of the different socio-economic needs and physical constraints of the coastal sub-units. Israel’s Coastal Environment Protection Law allows and, in fact, encourages the regulator to use discretion and to employ various criteria to balance development and conservation. This implies that policy makers are cognizant of a need to balance ecologically-sensitive boundaries that consider the homogeneity of the coast with politically feasible boundaries that are set arbitrarily.     

Coastal management, climate change adaptation and sustainability in small coastal communities: leatherback turtles and beach loss

Beaches are frequently subjected to erosion and accretion that are influenced by coastal development interventions and natural variations due to storms and changes in river flow. Climate change may also exacerbate beach erosion and accretion. Natural scientists are concerned with the sustainability of species dependent on the beach ecosystem. Policymakers are pre-occupied with the economic sustainability of coastal communities should species decline and prolonged beach loss occur. The aim of this paper is to explore the linkage between science and policy by reporting the findings of a study of coastal change impacts on leatherback turtle nesting and analysing the socio-economic and adaptation implications of these changes for coastal communities. Grande Riviere, Trinidad, was used as a case study. Primary fieldwork investigated unsustainable coastal management practices. A questionnaire was administered to examine livelihoods, including ecotourism based on leatherback turtle nesting, and knowledge and awareness of climate change. One key finding of the study was that the community’s livelihoods were natural resources dependent, and that natural beach dynamics and unsustainable coastal management practices posed major threats to natural resource and economic sustainability. Another key finding was that, despite these impacts, community knowledge and awareness of climate change in general was low, and there was a perception of state responsibility for climate change adaptation. The research findings have global applicability for coastal communities at risk of exposure and that are highly vulnerable to natural resources damage arising from anthropogenic stress and potential climate change. These communities require policy reforms to strengthen current coastal management practices and adaptation responses aimed at ensuring long-term sustainability.     

Effects of combustion and operating conditions on PCDD/PCDF emissions from power boilers burning salt-laden wood waste

This paper discusses the effects of combustion conditions on PCDD/PCDF emissions from pulp and paper power boilers burning salt-laden wood waste. We found no correlation between PCDD/PCDF emissions and carbon monoxide emissions. A good correlation was, however, observed between PCDD/PCDF emissions and the concentration of stack polynuclear aromatic hydrocarbons (PAHs) in the absence of TDF addition. Thus, poor combustion conditions responsible for the formation of products of incomplete combustion (PICs), such as PAHs and PCDD/PCDF precursors, increase PCDD/PCDF emissions. PAH concentrations increased with higher boiler load and/or low oxygen concentrations at the boiler exit, probably because of lower available residence times and insufficient excess air. Our findings are consistent with the current understanding that high ash carbon content generally favours heterogeneous reactions leading to either de novo synthesis of PCDD/PCDFs or their direct formation from precursors. We also found that, in grate-fired boilers, a linear increase in the grate/lower furnace temperature produces an exponential decrease in PCDD/PCDF emissions. Although the extent of this effect appears to be mill-specific, particularly at low temperatures, the results indicate that increasing the combustion temperature may decrease PCDD/PCDF emissions. It must be noted, however, that there are other variables, such as elevated ESP and stack temperatures, a high hog salt content, the presence of large amounts of PICs and a high Cl/S ratio, which contribute to higher PCDD/PCDFs emissions. Therefore, higher combustion temperatures, by themselves, will not necessarily result in low PCDD/PCDFs emissions.     

No evidence for offspring sex-ratio adjustment to social or environmental conditions in cooperatively breeding purple-crowned fairy-wrens

When fitness returns or production costs vary between male and female offspring, selection is expected to favor females that adjust offspring sex ratio accordingly. However, to what extent vertebrates can do so is the subject of ongoing debate. Here, we explore primary sex ratios in 125 broods of cooperatively breeding purple-crowned fairy-wrens Malurus coronatus. We expected that females might adjust offspring sex ratio because this passerine species experiences considerable variation in social and environmental conditions. (1) However, although helpers substantially increase parental fitness, females (particularly in pairs and small groups) did not overproduce philopatric males (helper-repayment hypothesis). (2) Sex-ratio adjustment based on competition among individuals (helper-competition hypothesis) did not conceal helper-repayment effects or drive sex allocation on its own: while high-quality territories can accommodate more birds, brood sex ratios were independent of territory quality, alone or in interaction with group size. (3) Additionally, males are larger than females and are possibly more costly to produce (costly sex hypothesis), and (4) female offspring may benefit more from long-term effects of favorable conditions early in life (Trivers–Willard hypothesis). Nonetheless, large seasonal variation in food abundance was not associated with a consistent skew in primary sex ratios. Thus, overall, our results did not support the main hypotheses of adaptive sex-ratio adjustment in M. coronatus. We discuss that long-term differential costs and benefits may be insufficient to drive evolution of primary sex-ratio manipulation by M. coronatus females. More investigation is therefore needed to determine the general required sex differences in long-term fitness returns for mechanisms of primary sex-ratio manipulation to evolve.     

Environmental fate of pesticides used in Australian viticulture: Behaviour of dithianon and vinclozolin in the soils of the South Australian Riverland

The red calcareous earth soils of the South Australian Riverland produce more than one-third of the grapes used in Australian winemaking. As part of on-going investigations into pesticide transport in Australian vineyard soils, the movement of the fungicides dithianon and vinclozolin through such strongly alkaline soils was investigated. Small, undisturbed soil cores were extracted from the inter-row topsoil of a vineyard adjacent to the River Murray, approximately 10 km S.W. of Overland Corner, South Australia. The vines were grown in a deep (1 – 4 m) reddish brown, strongly alkaline, sandy loam with a low organic carbon content (1 – 2 %). Surface fluxes of pesticide were applied at the maximum recommended application rates to the surface of the cores, which were then irrigated, and pesticide residues in the leachate determined by HPLC. No leaching of either dithianon or vinclozolin occurred. Dithianon was immobilised in the top 2 cm of the soil. Dithianon concentrations were low ( 0 – 37 % applied dose) suggesting that rapid degradation of this compound occurs in these soils (63 – 100 % degradation in 10 days). Extremely low concentrations of vinclozolin were found throughout the soil core profiles (0.05 – 1.4 % applied dose) suggesting that this fungicide was somewhat mobile, but also that it too was unstable in such alkaline soils (> 98 % degradation in 10 days). These results suggest that the irrigated vineyard soils of this region are unlikely to be prone to leaching of dithianon or vinclozolin, and therefore that groundwater supplies in this area are unlikely to be at any significant risk of contamination through viticultural use of these compounds.     

Fish Assemblage Response to a Small Dam Removal in the Eightmile River System,Connecticut, USA

We examined the effects of the Zemko Dam removal on the Eightmile River system in Salem, Connecticut, USA. The objective of this research was to quantify spatiotemporal variation in fish community composition in response to small dam removal. We sampled fish abundance over a 6-year period (2005–2010) to quantify changes in fish assemblages prior to dam removal, during drawdown, and for three years following dam removal. Fish population dynamics were examined above the dam, below the dam, and at two reference sites by indicator species analysis, mixed models, non-metric multidimensional scaling, and analysis of similarity. We observed significant shifts in fish relative abundance over time in response to dam removal. Changes in fish species composition were variable, and they occurred within 1 year of drawdown. A complete shift from lentic to lotic fishes failed to occur within 3 years after the dam was removed. However, we did observe increases in fluvial and transition (i.e., pool head, pool tail, or run) specialist fishes both upstream and downstream from the former dam site. Our results demonstrate the importance of dam removal for restoring river connectivity for fish movement. While the long-term effects of dam removal remain uncertain, we conclude that dam removals can have positive benefits on fish assemblages by enhancing river connectivity and fluvial habitat availability.     

Percolation of Lead(II) and Cadmium(II) through two bentonites used as landfill liner

In order to prevent contamination of subsoil and groundwater by leachates containing heavy metals, montmorillonite linings are used on landfill bottoms. It is therefore important to understand ion uptake by this clay. In this study we have performed percolation of lead(II) and cadmium(II) through columns filled firstly with a technical bentonite and then with a reference bentonite. Elution curves provide an evaluation of metals retention. After the percolation step, columns are cut and metal ions are extracted to evaluate influence of side effects and soil depth on metal uptake. Moreover retentions of lead(II) and cadmium(II) are compared.     

Importance of timely metadata curation to the global surveillance of genetic diversity

Genetic diversity within species represents a fundamental yet underappreciated level of biodiversity. Because genetic diversity can indicate species resilience to changing climate, its measurement is relevant to many national and global conservation policy targets. Many studies produce large amounts of genome-scale genetic diversity data for wild populations, but most (87%) do not include the associated spatial and temporal metadata necessary for them to be reused in monitoring programs or for acknowledging the sovereignty of nations or Indigenous peoples. We undertook a distributed datathon to quantify the availability of these missing metadata and to test the hypothesis that their availability decays with time. We also worked to remediate missing metadata by extracting them from associated published papers, online repositories, and direct communication with authors. Starting with 848 candidate genomic data sets (reduced representation and whole genome) from the International Nucleotide Sequence Database Collaboration, we determined that 561 contained mostly samples from wild populations. We successfully restored spatiotemporal metadata for 78% of these 561 data sets (n = 440 data sets with data on 45,105 individuals from 762 species in 17 phyla). Examining papers and online repositories was much more fruitful than contacting 351 authors, who replied to our email requests 45% of the time. Overall, 23% of our email queries to authors unearthed useful metadata. The probability of retrieving spatiotemporal metadata declined significantly as age of the data set increased. There was a 13.5% yearly decrease in metadata associated with published papers or online repositories and up to a 22% yearly decrease in metadata that were only available from authors. This rapid decay in metadata availability, mirrored in studies of other types of biological data, should motivate swift updates to data-sharing policies and researcher practices to ensure that the valuable context provided by metadata is not lost to conservation science forever.