Effects of Hypoxia on the Behavior and Physiology of Juvenile Stage Temperate Reef Fishes (Genus: Sebastes)

• Main Author: Gilman Mattiasen, Evan
• Format: Text
• Language: unknown
• Published: Digital Commons @ CSUMB 2018
• Subjects: hypoxia; climate change; rockfish; reef fish; copper rockfish; blue rockfish; ventilation rates; Ocean acidification
• Online Access: https://digitalcommons.csumb.edu/caps_thes_all/722; https://digitalcommons.csumb.edu/context/caps_thes_all/article/1742/viewcontent/Mattiasen_Thesis_APPROVED.pdf

The progression of climate change is predicted to cause large-scale changes to ocean chemistry (i.e., shifts in temperatures, salinity, ocean acidification, etc.) within the California Current. Forecasts from climate models and oceanographic observations indicate an increase in the frequency and duration of hypoxic events in the coastal zone, which have the potential to affect marine biodiversity and fisheries. Many studies have shown that exposure to extreme low dissolved oxygen (pO2) conditions can have deleterious effects on fish in early life stages, such as inhibition to growth and locomotion. Rockfish (Sebastes spp.) are a diverse group of species composed of fishes with varying life history characteristics. This study aims to determine how exposure of two species of young-of-the-year (YOY) juvenile rockfishes will perform under chronic exposure to varying dissolved oxygen levels. Copper rockfish (Sebastes caurinus) and blue rockfish (Sebastes mystinus) are two closely related species that differ in early life history traits. Copper rockfish have a short pelagic duration that begins with parturition in the spring and ends with recruitment to the kelp forest canopy after 1-2 months. Blue rockfish have a longer pelagic duration that begins in the winter and ends with recruitment to the benthic kelp forest habitat after 3-6 months. I compared how behavior and physiology were affected under chronic exposure to low pO2 at four treatment levels (ambient = 9.0 mg O2 L-1, moderate = 6.0 mg O2 L-1, low = 4.0 mg O2 L-1, hypoxic = 2.0 mg O2 L-1). Behavioral tests were aimed at identifying changes in exploratory behavior (i.e., escape response trial), predator detection through olfactory perception (i.e., olfactory choice test), and changes in turning preference (i.e., behavioral lateralization). Physiological tests focused on determining changes in hypoxia tolerance (critical oxygen tension, pCrit), the capacity for aerobic activity (i.e., aerobic scope), and ventilation rates. Changes in growth rates of both species ...