Essie Rodgers

In the Anthropocene, species are increasingly faced with multiple stressors that are more severe and less predictable than before. While multiple stressors often interact to affect organisms negatively, sometimes these interactions can be beneficial, enhancing resilience through cross-protection. Cross-protection interactions occur when exposure to one stressor, such as elevated temperature, enhances an organism’s tolerance to a different stressor, like hypoxia, through shared protective mechanisms or signaling pathways. Understanding the potential for cross-protection to combat rapid and diverse environmental change is crucial for conservation, as it potentially alters the predicted consequences of such change. Here, we outline 10 key considerations for investigating cross-protection in a conservation context. These considerations include the importance of stressor intensity and timing, recognizing species-specific and sex-specific responses, and embracing temporal variability in environmental stressors. Additionally, predictions will depend upon uncovering the underlying mechanisms of cross-protection by integrating emerging approaches like omics and meta-analyses. By better understanding—and in some cases explicitly leveraging—cross-protective interactions, conservation practitioners may be able to develop more effective management plans to enhance species resilience, potentially mitigating the immediate effects of emerging stressors. These insights are vital for guiding future research directions and informing conservation policies and management practices to preserve biodiversity in the Anthropocene.

In some estuaries, low inflow and/or isolation from the ocean can result in evapoconcentration and hypersalinity (≥40 ppt). This can create osmoregulatory and energetic challenges for the faunal community, leading to reductions in diversity as more species pass their thresholds. As climate change is increasing the magnitude and duration of hypersaline conditions, we used benthic macroinvertebrate data from 12 estuaries across a Mediterranean climatic region (southwestern Australia) to assess the influence of salinity (0–122 ppt) on the invertebrate fauna. Taxa richness and diversity were highest in salinities between 0 and 39 ppt, peaking at salinities closest to seawater, while total density peaked at 40–49 ppt. Beyond 50 ppt, these measures declined significantly. Community composition changed markedly along the salinity gradient. In lower salinities, communities were diverse, comprising polychaetes, malacostracans, hexapods, ostracods, bivalves, and gastropods. However, in salinities ≥50 ppt, many taxa declined, leading to communities dominated by polychaetes (mainly Capitella spp.) and hexapods (mostly larval chironomids). At 90 ppt, only polychaetes and hexapods remained, and at ≥110 ppt, only the latter taxon persisted. This faunal shift towards insect dominance in hypersaline conditions mirrors observations in other Mediterranean and arid/semi-arid regions, with the resulting communities resembling saline wetlands or salt lakes. This loss of invertebrates can substantially impact ecosystem functioning and trophic pathways, and the findings of this study provide a basis for predicting how these communities will respond to increasing hypersalinity driven by climate change.

Starting with the Remane diagram, various conceptual models have been proposed to show how species richness varies along a salinity gradient. However, as relatively few estuaries experience extreme hypersalinity, quantitative data are lacking to evaluate the model. We used data for 1891 samples of benthic macroinvertebrates from 12 estuaries in southwestern Australia (salinity 0–122 ppt) to determine the salinities in which 257 taxa were recorded. The pattern of richness differed from the conceptual models, with relatively few species (≤20%) recorded in freshwater and oligohaline salinities. Richness peaked at 35 ppt (seawater, 44%) before declining precipitously, with 21% and 10% of taxa recorded in hyperhaline salinities of 40 and 48 ppt, respectively. Taxa were recorded across the full salinity range, and several holohaline annelids, crustaceans, and insects were identified. Descriptive statistics and the frequency distribution of each taxon along the salinity gradient are provided. These identify stenohaline taxa and those with different extents of euryhalinity and how the occurrence of these taxa changes with salinity. The results help predict how benthic macroinvertebrate species and assemblages in estuaries in southwestern Australia and other Mediterranean climatic regions may shift due to climate change, particularly increased incidences and magnitude of hypersalinity.

Purpose
Extreme weather events including drought, flooding, and wildfires resulting from climate change can impact ecosystems. Various toxic substances are emitted during wildfires, such as particulate matter and volatile organic compounds, as the frequency and intensity of wildfires rise with climate change. This review aims to focus on the effects of wildfires on environmental health covering contaminants in soil, aquatic and atmospheric environment.

Materials and methods
A thorough literature search was conducted in Web of Science Core Collections with the following keywords: “wildfire” OR “volatile organic compounds” OR “pollution” OR “contamination” OR “terrestrial pollution” OR “aquatic pollution” OR “atmospheric pollution”. PRISMA flow chart was used to highlight the review's content and provide a more thorough synthesis of relevant studies.

Results and discussion
Various studies have shown how wildfire emissions affect the public health, although handful information available regarding the environmental health impacts of smoke emissions during wildfires. The post-wildfire trace elemental concentrations and speciation are notably linked to plant species, geology, and topography. Recent studies found increased levels of nitrogen (N), phosphorus (P), dissolved organic carbon (DOC), suspended solids, and water turbidity in lakes within wildfire-burnt watersheds. The response of individual ecosystems to wildfire depends on proximity to the fire, fire characteristics, fuel fee material burned, the effect of fundamental drivers of water quality.

Conclusions
The findings of this review will encourage and strengthen collaboration between the scientific community and regulatory agencies to better understand how erratic weather events, such as wildfires, may affect the health of people and animals.
[Display Omitted]

Scylla olivacea, or the mud crab, is a crucial economic contributor in Southeast Asia, notably in the coastal region of the Ganges-Brahmaputra delta. This study compared the nutritional and heavy metals of fattened and wild-captured mud crabs from the southwest coastal areas of the Ganges-Brahmaputra delta, focusing on proximate composition, fatty acids, amino acids, and heavy metals. Fattened mud crabs showed higher crude protein levels (13.2%–14.4%), particularly in males, and higher crude fat and ash contents than their wild counterparts. Among fatty acids, fattened crabs had the highest palmitic acid levels (34.0%–41.2%), whereas wild crabs were rich in linoleic and linolenic acids. Amino acid analysis revealed that histidine and arginine were the most prevalent essential amino acids in fattened and wild crabs, respectively. Elemental analysis indicated that calcium levels were high in both groups. However, zinc, copper, iron, and manganese concentrations exceeded recommended dietary allowances. Furthermore, the wild mud crabs contained heavy metals lower than that of the fattened mud crabs. Notably, nickel, lead, and cadmium levels surpassed maximum permissible limits, suggesting potential health risks in fattened and wild mud crabs. The concentration of Omega-3 fatty acids was higher in wild crabs than in cultured ones. These findings emphasize the need for cautious consumption and strict monitoring in mud crab aquaculture to ensure food safety and sustainability.

Climate warming is seeing temperatures breach exceptional thresholds as the frequency and intensity of heat waves increase. Efforts to forecast species vulnerability to climate warming often focus on upper thermal limits threatening survival, overlooking the role of intraspecific variation in determining vulnerability. Using an estuarine fish (black bream, Acanthopagrus butcheri) as a model, we explore how intraspecific variation in body mass and among populations affects upper thermal tolerance. Upper thermal limits were quantified using critical thermal maxima (CTmax) of wild fish. We used a ∼500 g (mean = 52.4 g, range = 0.57 – 541 g) mass range to test the relationship between body mass and thermal tolerance. Four distinct black bream populations were chosen along a 5° latitudinal cline to explore population differences in thermal limits. Contrary to expectations, there was no effect of body mass on upper thermal limits. However, significant population differences in thermal tolerance were observed that correlate with mean habitat temperatures. Specifically, the southern population had a significantly lower CTmax (35.57 ± 0.43 °C) compared to northern (36.32 ± 0.70 °C) and mid-latitude (36.36 ± 1.15 °C) populations. These data underscore the importance of observing intraspecific variation in thermal limits to reveal the capabilities of individuals within a species to cope with climate warming and improve the management of at-risk life stages and populations.
•Upper thermal limits of black bream were assessed along a 5° latitudinal cline•Upper thermal limits did not scale with body mass over a 500g range (0.57 – 541 g)•Mean annual temperature range best explained differences in CTmax•Southern population had a significantly lower CTmax compared to northern populations

Vertebrate sex is typically determined genetically, but in many ectotherms sex can be determined by genes (Genetic Sex Determination: GSD), temperature (Temperature-dependent Sex Determination: TSD), or interactions between genes and temperature during development. Temperature dependent sex determination may involve GSD systems with either male or female heterogamety (XX/XY or ZZ/ZW) where temperature overrides chromosomal sex determination to cause a mismatch between genetic sex and phenotypic sex (sex-reversal). In these temperature-sensitive lineages, phylogenetic investigations point to recurrent evolutionary shifts between genotypic and temperature-dependent sex determination. These evolutionary transitions in sex determination can occur rapidly if selection favours the reversed sex over their concordant phenotypic sex. To investigate the consequences of sex-reversal on offspring phenotypes, we measured two energy-driven traits (metabolism and growth) and 6-month survival in two species of reptile with different patterns of temperature-induced sex-reversal. Male sex-reversal occurs in Bassiana duperreyi when chromosomal females (femaleXX) develop male phenotypes (maleSRXX), while female sex-reversal occurs in Pogona vitticeps when chromosomal males (maleZZ) develop female phenotypes (femaleSRZZ). We show metabolism in maleSRXX was like that of maleXY, that is, reflective of phenotypic sex and lower than genotypic sex. In contrast, for Pogona vitticeps, femaleSRZZ metabolism was intermediate between maleZZ and femaleZW metabolic rate. For both species, our data indicate that differences in metabolism become more apparent as individuals become larger. Our findings provide some evidence for an energetic advantage from sex-reversal in both species but do not exclude energetic processes as a constraint on the distribution of sex-reversal in nature.

Nitrogen-based fertilizers can increase agricultural yields and crop quality, but this comes at the risk of contaminating nearby waterways. Nitrate is the most stable and abundant form of inorganic nitrogen in the environment and chronic exposure can impair performance and fitness in aquatically respiring species. But it remains unknown if these impairments are linked to disruptions in energy homeostasis. Here, we investigated the energetic cost of living in nitrate contaminated waters during early, energy-limited, larval life stages in the endangered southern bell frog (Litoria raniformis). We hypothesised that chronic nitrate exposure during development would increase energetic costs, evidenced by reductions in growth rates and body sizes, and elevations in routine heart rate (RHR) and routine metabolic rate (RMR). Following hatching, larvae were exposed to one of three nitrate treatments (0, 25 and 50 mg NO3−L−1) for 12 weeks, and survival, growth, RHR, and RMR were measured. Survival rates were similar across all treatments. Nitrate exposure caused a reduction in growth rates, resulting in larvae with significantly smaller body sizes. Compared to controls, nitrate-exposed larvae were 12% and 18% smaller in total length in the 25 and 50 mgNO3−L−1 treatments, respectively. However, RHR and RMR were independent of nitrate exposure, indicating that the ‘cost of living’ was similar across treatments. Observed growth reductions were therefore independent of RHR and RMR, suggesting other mechanisms were involved. Taken together, these results highlight the vulnerability of L. raniformis to nitrate during early life and suggest that the application of nitrogen-based fertilizers near critical aquatic habitats will be harmful.

Aquatic habitats encompass some of the most complex and dynamic environs on earth, leaving fish to navigate multiple, interacting stressors. Fish regularly contend with shifts in key environmental conditions in combination with biotic challenges and anthropogenic pressures. Stressors are becoming more numerous and severe owing to human pressures, and multi-stressor studies are critical to building an understanding of how fish physiology is affected by multivariate phenomena, like climate change. In this article, we explore how fish physiologically respond to multivariate changes in their environment, paying particular attention to non-additive stressor interactions where “ecophysiological surprises” are revealed.