Developing drought resilience in irrigated agriculture in the face of increasing water scarcity

Regional Environmental Change - In many countries, drought is the natural hazard that causes the greatest agronomic impacts. After recurrent droughts, farmers typically learn from experience and...     

Motile cryptofauna associated with live and dead coral substrates: implications for coral mortality and framework erosion

Coral reef cryptofauna are a diverse group of metazoan taxa that live within intra- and inter-skeletal voids formed by framework structures. Despite a hypothesized high biomass and numerous trophic roles, they remain uncharacterized relative to exposed reef communities. Motile cryptofauna were sampled from live coral colonies and dead frameworks typifying four successive levels of degradation on an eastern Pacific pocilloporid reef. Abundances and biomass were higher on live versus dead corals habitats. The density of cryptofauna per volume substrate was highest on dead coral frameworks of intermediate degradation, where complex eroded substrates provide abundant shelters. These data have important and far-reaching ramifications for how the diverse multispecies assemblages that are reef ecosystems will respond to anthropogenic stressors such as those associated with climate change. Extreme levels of coral mortality, bioerosion, and habitat destruction will lead to impairment and eventually loss of ecosystem functions.     

Parasite competition hidden by correlated coinfection: using surveys and experiments to understand parasite interactions

Within most free-living species exists a cryptic community of interacting parasites. By combining multiscale field data with manipulative experiments, we evaluated patterns of parasite coinfection in amphibian hosts and their underlying mechanisms. Surveys of 86 wetlands and 1273 hosts revealed positive correlations between two pathogenic trematodes (Ribeiroia ondatrae and Echinostoma trivolvis) both between wetlands and within individual hosts. In infection and coinfection experiments, Ribeiroia caused greater pathology than Echinostoma, including high host mortality (24%) and severe limb malformations (75%). No interactive effects were noted for host pathology, but both parasites decreased the per capita persistence of one another by 17-36%. Thus, in spite of consistently positive associations from field data, these parasites negatively affected the persistence of one another, likely via cross immunity (apparent competition). These findings underscore the danger of inferring parasite interactions from coinfection patterns and emphasize the potential disconnect between within-host processes (e.g., competition) and between-host processes (e.g., exposure and transmission). Here, correlated coinfections likely resulted from similarities in the parasites' host requirements and heterogeneity in host susceptibility or exposure. Understanding complex interactions among parasites depends critically on the scale under consideration, highlighting the importance of combining coinfection field studies with mechanistic experiments.     

Predicting structural complexity of reefs and fish abundance using acoustic remote sensing (RoxAnn)

This study determined whether the acoustic roughness of Caribbean reef habitats is an accurate proxy for their topographic complexity and a significant predictor of their fish abundance. Fish abundance was measured in 25 sites along the forereef of Glovers Atoll (Belize). At each site, in situ rugosity (ISR) was estimated using the “chain and tape” method, and acoustic roughness (E1) was acquired using RoxAnn. The relationships between E1 and ISR, and between both E1 and ISR and the abundance of 17 common species and the presence of 10 uncommon species were tested. E1 was a significant predictor of the topographic complexity (r ² = 0.66), the abundance of 10 common species of surgeonfishes, pomacentrids, scarids, grunts and serranids and the presence of 4 uncommon species of pomacentrids and snappers. Small differences in E1 (i.e. ∆0.05–0.07) reflected in subtle but significant differences in fish abundance (~1 individual 200 m⁻² and 116 g 200 m⁻²) among sites. Although we required the use of IKONOS data to obtain a large number of echoes per site, future studies will be able to utilise RoxAnn data alone to detect spatial patterns in substrate complexity and fish abundance, provided that a minimum of 50 RoxAnn echoes are collected per site.     

A comparative study of an innate immune response in Lamprologine cichlid fishes

Social interactions facilitate pathogen transmission and increase virulence. Therefore, species that live in social groups are predicted to suffer a higher pathogen burden, to invest more heavily in immune defence against pathogens, or both. However, there are few empirical tests of whether social species indeed invest more heavily in immune defence than non-social species. In the current study, we conducted a phylogenetically controlled comparison of innate immune response in Lamprologine cichlid fishes. We focused on three species of highly social cichlids that live in permanent groups and exhibit cooperative breeding (Julidochromis ornatus, Neolamprologus pulcher and Neolamprologus savoryi) and three species of non-social cichlids that exhibit neither grouping nor cooperative behaviour (Telmatochromis temporalis, Neolamprologus tetracanthus and Neolamprologus modestus). We quantified the innate immune response by injecting wild fishes with phytohaemagglutinin (PHA), a lectin that causes a cell-mediated immune response. We predicted that the three highly social species would show a greater immune reaction to the PHA treatment, indicating higher investment in immune defence against parasites relative to the three non-social species. We found significant species-level variation in immune response, but contrary to our prediction, this variation did not correspond to social system. However, we found that immune response was correlated with territory size across the six species. Our results indicate that the common assumption of a positive relationship between social system and investment in immune function may be overly simplistic. We suggest that factors such as rates of both in-group and out-group social interactions are likely to be important mediators of the relationship between sociality and immune function.     

Semen quality as a potential susceptibility indicator to SARS-CoV-2 insults in polluted areas

Environmental Science and Pollution Research - The epidemic of the new severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has impacted worldwide with its infectious spread and mortality...     

Application of the paleolimnological method to assess metal contaminant distribution (As,Cu, Pb,Zn) in pulp mill stabilization basin sediments,Nova Scotia,Canada

Environmental Science and Pollution Research - The paleolimnological method was used to decouple geogenic and anthropogenic metal (loids) contributions in a sediment stabilization basin (Boat...     

Parentally biased favouritism in relation to offspring sex in zebra finches

Family conflicts over parental care result in offspring attempting to exert control using solicitation behaviours, whilst the parents are potentially able to retaliate through provisioning rules. However, the evolutionary interests of one parent may not necessarily support the evolutionary interests of the other parent, and such conflicts of interest may be expressed in how the two parents allocate the same form of parental care to individual offspring. Theory suggests that such parentally biased favouritism is a universally predicted outcome of evolutionary conflicts of interest, and empirical evidence suggests that parentally biased favouritism occurs in relation to offspring size and solicitation behaviours. However, unequivocal empirical evidence of parentally biased favouritism in relation to offspring sex is absent, due to being strongly confounded by sex differences in size and solicitation behaviours. Here, we present strong evidence for parentally biased favouritism in relation to offspring sex in zebra finches (Taeniopygia guttata), independent of the effects of chick size and begging intensity. Mothers preferentially provisioned sons over daughters, whilst fathers showed no bias, meaning that sons received more food than daughters. Parentally biased favouritism in relation to offspring sex facilitates parental control over evolutionary conflicts of interest and is probably more widespread than previously realised.