No effects of plasticized microplastics on the body condition and reproduction of a marine fish

This study experimentally explored the influence of periodic consumption of polystyrene (PS) microplastic fragments on the body condition and fitness of a tropical marine fish. Adult damselfish, Acanthochromis polyacanthus, were pulse fed microplastic fragments bound with one of two different common plasticizers [di-2-ethylhexyl phthalate (DEHP), di-2-ethylhexyl terephthalate (DEHT)] together with virgin-plastic and no-plastic controls. Ingestion of plastic over a 150d period had no detectable effect on growth, indices of body condition, or gonadosomatic indices. Histology of the liver showed no detrimental effects of ingesting any of the plastic treatments on hepatocyte density or vacuolation. Plastic consumption had no effect on the number of clutches produced over the breeding period, the number of eggs, or the survival of embryos. It is believed that the relatively inert nature of PS, the low amount of plasticizers leached from the fragments and fast gut through-put times meant fish were exposed to low levels of toxic compounds

Boat noise affects the early life history of two damselfishes

Anthropogenic noise can have a negative effect on the physiology and survival of marine fishes. Most research has focused on later life-stages, and few studies have investigated the effects of human-induced noise on embryogenesis. The current study investigated whether playback of motorboat noise affected the embryogenesis of the coral reef damselfishes, Amphiprion melanopus and Acanthochromis polyacanthus. Embryos reared under the playback of boat noise had faster heart rates compared to the ambient reef controls. The effects of noise on morphological development differed between species and the fundamental interrelationships between early life history characteristics changed dramatically under boat noise for Ac. polyacanthus. Noise treatments did not alter the survival rates of embryos under laboratory conditions. Although species specific, our findings suggest that anthropogenic noise causes physiological responses in fishes during embryogenesis and these changes have direct impacts on their development and these alterations may have carry-over effects to later life stages

Coral degradation alters predator odour signatures and influences prey learning and survival

Habitat degradation is a key factor leading to the global loss of biodiversity. This problem is particularly acute in coral reef ecosystems. We investigated whether recognition of predator odours by damselfish was influenced by coral degradation and whether these changes altered survival in the wild. We taught whitespot damselfish to recognize the odour of a predator in the presence of live/healthy coral or dead/degraded coral. Fish were tested for a response to predator odours in environments that matched their conditioning environment or in environments that were mismatched. Next, we taught blue damselfish to recognize the odour of three common reef predators in live and degraded coral environments and then stocked them onto live or degraded patch reefs, where we monitored their subsequent response to predator odour along with their survival. Damselfish learned to recognize predator odours in both coral environments, but the intensity of their antipredator response was much greater when the conditioning and test environments matched. Fish released on degraded coral had about 50% higher survival if they had been trained in the presence of degraded coral rather than live coral. Altering the intensity of antipredator responses could have rather profound consequences on population growth