Abstract
In nature, a multitude of both abiotic and biotic stressors influence organisms with regard to their overall fitness. Stress responses that finally impair normal biological functions may ultimately result in consequences for whole populations. This study focused on the metabolic response of the intertidal rock pool fish Gobius paganellus towards simulated predation risk. Individuals were exposed to a mixture of skin extracts from conspecifics and chemical alarm cues from a top predator, Octopus vulgaris. Oxygen consumption rates of single fish were measured to establish standard (SMR) and routine metabolic rates (RMR) of G. paganellus, and to address the direct response towards simulated predation risk, compared to handling and light stress. The SMR of G. paganellus (0.0301 ± 0.0081 mg O2 h-1 g-1 WW) was significantly lower than the RMR (0.0409 ± 0.0078 mg O2 h-1 g-1 WW). In contrast to increased respiration due to handling and light stress, the exposure to chemical predation cues induced a significant reduction in oxygen consumption rates (0.0297 ± 0.0077 mg O2 h-1 g-1 WW). This metabolic suppression was interpreted as a result of the stereotypic freezing behaviour as antipredator response of gobiid fish. Results underline the importance of biotic interactions in environmental stress assessments and predation as a biotic factor that will provide more realistic scenarios when addressing stress impacts in tidal rock pool organisms.
Highlights
In an ecosystem, both abiotic and biotic stressors may affect organisms and have impacts on somatic growth, reproduction, and disease resistance, which might result in consequences for whole populations (e.g., [1,2,3,4,5,6,7])
For G. paganellus (n = 13), the mean standard metabolic rate (SMR) was 0.0301 ± 0.0081 mg O2 h-1 g-1 wet weight (WW), which was significantly lower than the mean routine metabolic rates (RMR) being 0.0409 ± 0.0078 mg O2 h-1 g-1 WW
oxygen consumption (OC) rates at handling stress were significantly higher than RMR (Games-Howell, P = 0.021) and SMR (Games-Howell, P = 0.003)
Summary
Both abiotic and biotic (e.g., intra- and/or interspecific competition for space, food, mating partners) stressors may affect organisms and have impacts on somatic growth, reproduction, and disease resistance, which might result in consequences for whole populations (e.g., [1,2,3,4,5,6,7]). Organisms are often more vulnerable to biotic stressors [8]. Biotic interactions can affect the individuals’ ability to cope with abiotic stress [9,10]. One of the most prominent biotic interactions is the predator/ prey relation. From the prey’s point of view, proper predation risk assessment is of life-saving importance (reviewed by [11]). Fish that are able to avoid high-risk areas [12] can significantly
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