Temperature variation and heat waves
Central predictions of climate change are that, in addition to increases in mean habitat temperatures, species will face increased climate variability, with more frequent heat waves. This is true for terrestrial and aquatic habitats alike. The increased probability of extreme habitat temperatures will lead to future heat waves that are longer in duration, with warmer maximal temperatures. My research aims to detail the responses of ectothermic (“cold-blooded”) animals to temperature variation and heat waves. I am using a mixture of experimental and meta-analytical tools to test how ectothermic animals cope under warmer and more variable temperature extremes.
Multiple stressors
The acceleration of anthropogenic activity has caused novel or extreme environmental challenges for species to navigate. Species must now contend with complex combinations of environmental threats which include habitat degradation, pollution and climate change. Yet, the lack of available data on how species cope when confronted with multiple environmental challenges poses a significant challenge to conservation. Nutrient pollution is regarded as one of the most common and widespread forms of habitat degradation. Anthropogenic activities have caused a rampant increase in nitrate (NO3−) concentrations, peaking at concentrations above 100 mg NO3− L-1. Aquatically respiring organisms (e.g., fish, crustaceans) are particularly vulnerable to elevated nitrate concentrations, causing significant physiological and behavioural alterations. These alterations may be exacerbated by the presence of additional threats (low oxygen conditions, low pH, elevated temperatures), but information on the interactive effects of nitrate and other environmental stressors is scarce. As such, the overarching aim of this research was to investigate species responses to multiple environmental stressors, specifically how nitrate interacts with other stressors to affect physiological function, organismal performance and tolerance limits.
Can diet change the ‘thermal phenotype’ of fish?
Aquatic organisms, including important cultured species, are being forced to contend with sudden changes in water temperature as the frequency and intensity of extreme weather events worsen. Acute temperature spikes are likely to threaten aquaculture species, but dietary intervention may play an important protective role. Diet can shape the thermal resilience of aquaculture species and allow fish to tolerate otherwise deadly temperatures. In the literature, several dietary intervention techniques, such as the manipulation of vitamins (vitamins A, B, C), heavy metals (zinc, selenium), probiotics and even algae, have been trialed all with varying effects on the thermal tolerance of fish. This project aims to understand how different diet supplements affect the thermal physiology (thermal tolerance, growth, disease susceptibility) of important aquaculture species (salmon, barramundi).
Contact
Harry Butler Institute, Murdoch University Perth WA 6150 Australia
Email: daniel.gomezisaza@uq.net.au
Phone: +61 413 633 561
Daniel Gomez Isaza 