Browsing by Author "Kline, David I."
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Item Effects of ocean acidification on dopamine-mediated behavioral responses of a coral reef damselfish(2023) Hamilton, Trevor; Tresguerres, Martin; Kwan, Garfield T.; Szaszkiewicz, Joshua; Franczak, Brian C.; Cyronak, Tyler; Andersson, Andreas J.; Kline, David I.We investigated whether CO2-induced ocean acidification (OA) affects dopamine receptor-dependent behavior in bicolor damselfish (Stegastes partitus). Damselfish were kept in aquaria receiving flow through control (pH ~ 8.03; pCO2 ~ 384 μatm) or OA (pH ~ 7.64; CO2 ~ 1100 μatm) seawater at a rate of 1 L min−1. Despite this relatively fast flow rate, fish respiration further acidified the seawater in both control (pH ~7.88; pCO2 ~ 595 μatm) and OA (pH ~7.55; pCO2 ~ 1450 μatm) fish-holding aquaria. After five days of exposure, damselfish locomotion, boldness, anxiety, and aggression were assessed using a battery of behavioral tests using automated video analysis. Two days later, these tests were repeated following application of the dopamine D1 receptor agonist SKF 38393. OA-exposure induced ceiling anxiety levels that were significantly higher than in control damselfish, and SKF 38393 increased anxiety in control damselfish to a level not significantly different than that of OA-exposed damselfish. Additionally, SKF 38393 decreased locomotion and increased boldness in control damselfish but had no effect in OA-exposed damselfish, suggesting an alteration in activity of dopaminergic pathways that regulate behavior under OA conditions. These results indicate that changes in dopamine D1 receptor function affects fish behavior during exposure to OA. However, subsequent measurements of seawater sampled using syringes during the daytime (~3–4 pm local time) from crevasses in coral reef colonies, which are used as shelter by damselfish, revealed an average pH of 7.73 ± 0.03 and pCO2 of 925.8 ± 62.2 μatm; levels which are comparable to Representative Concentration Pathway (RCP) 8.5 predicted end-of-century mean OA levels in the open ocean. Further studies considering the immediate environmental conditions experienced by fish as well as individual variability and effect size are required to understand potential implications of the observed OA-induced behavioral effects on damselfish fitness in the wild.Item Shoaling behaviour is differentially altered by ethanol and dopamine D1 receptor modulators in tropical marine forage fish(2018) Hamilton, Trevor; Kline, David I.; Tresguerres, MartinAnchovies are filter-feeding fish that inhabit nearshore environments worldwide. With increasing human pharmaceutical use, drugs that alter neurological functioning are becoming more prevalent in aquatic ecosystems via wastewater effluent, creating the need for tests that can reliably determine sublethal effects of these drugs on coastal fish populations. In this study, we used Caribbean anchovies (Anchoa spp.) as a tropical marine fish model to test drug-induced alterations of locomotion and shoaling behaviour with a video-based analysis system. Consistent with its anxiolytic effects in zebrafish (Danio rerio), ethanol decreased shoal cohesion in anchovies. We also characterized the effects of drugs known to modulate the dopaminergic system in zebrafish and rodents. A D1 receptor agonist (SKF 38393) and a D1 receptor antagonist (SCH 23390) increased the time anchovy spent in the center of the arena, but neither drug had an impact on shoal cohesion. Finally, the D1 receptor agonist caused significantly lower meandering compared with fish treated with the D1 receptor antagonist and ethanol. This study suggests that anchovy is a suitable Caribbean marine model for toxicology studies.