The Impacts of Climate Change on Blackeye Goby, Rhinogobiops nicholsii, Stress Responses, Reproduction, and Offspring Fitness

• Main Author: Yarbrough, Alora
• Format: Text
• Language: unknown
• Published: Digital Commons @ CSUMB 2022
• Subjects: climate change; blackeye gobies; ocean acidification; hypoxia; egg cortisol; reproduction; stress response; Ocean acidification
• Online Access: https://digitalcommons.csumb.edu/caps_thes_all/1331; https://digitalcommons.csumb.edu/cgi/viewcontent.cgi?article=2368&context=caps_thes_all

Along with warming and sea level rise, the increasing intensity of ocean acidification (OA) and hypoxia events in coastal environments is of large concern as climate change progresses. Weakened immune function, altered reproductive output, reduced aerobic scope, and hyperventilation are just some of the ways OA and hypoxia negatively affect fish. Under stress, such as OA or hypoxia, fish will produce the hormone cortisol to maintain homeostasis, so cortisol concentration can be used to determine the relative stress an animal is experiencing. This study evaluated the stress response of adult female blackeye gobies under both acute and chronic exposure to environmental stressors by measuring muscular cortisol concentrations at specific time points from fish placed in one of four different treatments: control (8.1 pH; ~9 mg/L O2), low DO (8.1 pH; 2.0 mg/L O2), low pH (7.3 pH; ~9 mg/L O2), and a combination of low DO and low pH (7.3 pH; 2.0 mg/L O2). Additionally, some larval fish rely entirely on maternally derived hormones supplied by the yolk sac immediately after hatching. An increase in cortisol in the yolk supply may cause developmental disadvantages, but there is also evidence that it can better equip offspring to face the stressors experienced by their mothers. Therefore, the relationship between maternal muscular and whole egg cortisol concentrations was investigated with females laying clutches under each of the four treatments. After spawning, clutches were split to be incubated under the same conditions their mothers experienced or the control treatment. At 1 day post hatch, offspring physiological fitness was evaluated based on morphometric characteristics and standard metabolic rate. This study observed that adult female blackeye gobies experiencing acute stress tend to have higher cortisol concentrations than those under chronic stress. While under acute stress, blackeye gobies had the strongest stress response under the low pH treatment, followed by the combined stressors, with the response to the ...