Data from: Prozac in the water: chronic fluoxetine exposure and predation risk interact to shape behaviors in an estuarine crab

Predators exert considerable top-down pressure on ecosystems by directly consuming prey or indirectly influencing their foraging behaviors and habitat use. Prey is, therefore, forced to balance predation risk with resource reward. A growing list of anthropogenic stressors such as rising temperatures and ocean acidification has been shown to influence prey risk behaviors and subsequently alter important ecosystem processes. Yet, limited attention has been paid to the effects of chronic pharmaceutical exposure on risk behavior or as an ecological stressor, despite widespread detection and persistence of these contaminants in aquatic environments. In the laboratory, we simulated estuarine conditions of the shore crab, Hemigrapsus oregonensis, and investigated whether chronic exposure (60 days) to field-detected concentrations (0, 3, and 30 ng/L) of the antidepressant fluoxetine affected diurnal and nocturnal risk behaviors in the presence of a predator, Cancer productus. We found that exposure to fluoxetine influenced both diurnal and nocturnal prey risk behaviors by increasing foraging and locomotor activity in the presence of predators, particularly during the day when these crabs normally stay hidden. Crabs exposed to fluoxetine were also more aggressive, with a higher frequency of agonistic interactions and increased mortality due to conflicts with conspecifics. These results suggest that exposure to field-detected concentrations of fluoxetine may alter the trade-off between resource acquisition and predation risk among crabs in estuaries. This fills an important data gap, highlighting how intra- and interspecific behaviors are altered by exposure to field concentrations of pharmaceuticals; such data more explicitly identify potential ecological impacts of emerging contaminants on aquatic ecosystems and can aid water quality management.

捕食者可通过直接捕食猎物，或间接影响其觅食行为与栖息地选择，对生态系统施加显著的下行调控压力。因此，猎物不得不权衡捕食风险与资源收益之间的利弊。日益增多的人为胁迫因子（如升温、海洋酸化）已被证实会影响猎物的风险应对行为，进而改变关键生态系统过程。然而，尽管这类药物污染物在水生环境中已被广泛检出且持续存在，学界对慢性药物暴露对猎物风险行为的影响，以及其作为生态胁迫因子的研究仍较为匮乏。本研究在实验室中模拟了Oregon厚纹蟹（Hemigrapsus oregonensis）的河口生存环境，探究了为期60天的慢性暴露——以野外实测浓度（0、3、30 ng/L）的抗抑郁药氟西汀（fluoxetine）——是否会改变猎物在捕食者首长黄道蟹（Cancer productus）存在时的昼夜风险应对行为。研究发现，氟西汀暴露会改变猎物的昼夜风险应对行为：在捕食者存在的情况下，受试蟹的觅食与运动活跃度显著提升，尤其在本应隐蔽栖息的白昼时段。暴露于氟西汀的受试蟹还表现出更强的攻击性，同种间争斗行为的发生频率更高，且因同类冲突导致的死亡率也有所上升。上述结果表明，暴露于野外实测浓度的氟西汀，可能会改变河口蟹类在资源获取与捕食风险之间的权衡策略。本研究填补了一项重要的数据空白，揭示了野外浓度的药物暴露如何改变物种的种内与种间行为；此类数据可更明确地识别新型污染物对水生生态系统的潜在生态影响，进而助力水环境质量管理。