Fish Hearts:
By Nishad Jayasundara Awards: Myers |
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Fishing in Antarctica |
My research focuses on understanding physiological adaptations to environmental temperature changes in marine fish.
Organisms have been able to inhabit an enormously diverse range of environments. They have altered a common set of biochemical structures to survive and thrive in an array of physical, chemical and biotic stresses presented to them by the environment they live in. These alterations in their physiology vary depending on the magnitude and the duration of a particular environmental stress.
During its lifetime an organism can induce gene and protein level responses to reset its physiology to best survive the changes in environmental conditions through a process known as acclimatization. The process of acclimatization can alter the critical threshold of a certain stress for a given organism, therefore maintaining or increasing its fitness in a given environment. This ability of an organism to alter its physiology during its lifetime depending on biotic and abiotic factors is known as phenotypic plasticity. |
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| Marine organisms may experience variation in one or more physical and chemical factors in their environment, depending on the habitat in which the species occurs. Temperature and levels of dissolved oxygen, pH and salinity are commonly varying environmental factors in the marine environment. Similar to other organisms, marine fish respond to temperature stress at the behavioral and physiological levels. |
Antarctic fish, Trematomus bernacchii |
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 Measuring fish heart rates |
Despite the obvious advantages of phenotypic plasticity, the energetic costs associated with this type of adaptive response might play a significant role in the ultimate fitness of a given species. To compensate for environmental stresses like temperature under optimum energy consumption, organisms have to remodel their physiology. This process requires efficient and adequate transport of material and humoral messages to all body cells. The circulatory system serves these purposes by providing oxygen and fuels for energy production and distributing cellular products through the body. Therefore, heart, as the power supply of the circulatory system, can be considered as an important focal point of physiological plasticity. Cardiac function in teleosts is known to be profoundly affected by temperature changes suggesting that cardiac limitations might define thermal boundaries for ectothermic organisms including marine teleosts. Considering the significance of cardiac function, I am interested in learning about fish heart responses to temperature and how it is related to the phenotypic plasticity of the animal. |
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I am investigating gene, protein, enzyme and whole organ level responses to acute and chronic temperature stress in cardiac muscle tissues of three physiologically and ecologically distinct families of fish – Gobiidae (longjaw mudsucker, Gillichthys spp), Nototheniidae (Antarctic fish, Trematomus spp) and Scombridae (bluefin tuna, Thunnus spp). These fish species from each family represents a group of ectothermic eurythermal and stenothermal (ability to tolerate a wide range and a narrow range of temperatures) and endothermic eurythemal fish species respectively. Studies such as this further our understanding of phenotypic plasticity of cardiac muscle tissues and may provide insights into which species are better or poorer adapted to climate temperature changes.
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