Understanding the impact of noise on marine fauna at the population level requires knowledge about the vulnerability of different life-stages. Here we provide the first evidence that noise exposure during larval development produces body malformations in marine invertebrates. Scallop larvae exposed to playbacks of seismic pulses showed significant developmental delays and 46% developed body abnormalities. Similar effects were observed in all independent samples exposed to noise while no malformations were found in the control groups (4881 larvae examined). Malformations appeared in the D-veliger larval phase, perhaps due to the cumulative exposure attained by this stage or to a greater vulnerability of D-veliger to sound-mediated physiological or mechanical stress. Such strong impacts suggest that abnormalities and growth delays may also result from lower sound levels or discrete exposures during the D-stage, increasing the potential for routinely-occurring anthropogenic noise sources to affect recruitment of wild scallop larvae in natural stocks.

Marine organisms are constantly exposed to stress, such as changes in seawater temperature, which may elicit biochemical, molecular, and physiological changes. In the present study, an integrative approach to evaluate stress in the green-lipped mussel Perna canaliculus exposed to control, moderate, and severe heat stress was used. Flow cytometry (FCM) was used to measure hemolymph parameters, including hemocyte concentration, viability, and reactive oxygen species (ROS) production. Spectrophotometry and a handheld electrochemical meter were used to determine the total antioxidant capacity (TAC) of hemolymph and gill tissue, and metabolomics was used to contrast specific metabolic responses among treatments. For hemolymph parameters measured using FCM, the number of nonviable hemocytes increased with the severity of heat shock. The proportion of superoxide-positive hemocytes mirrored the increase in nonviability; by contrast, the general ROS production initially increased following moderate heat shock, but then decreased after severe heat shock. Trolox-equivalent antioxidant capacity in the gill tissue and fast-acting antioxidant levels in the haemolymph showed small but significant decreases following heat shock, whereas the reciprocal pattern was seen for slow-acting and TAC in the hemolymph. Metabolomic profiles discriminated between treatments, with energy metabolism pathways appearing the most affected. The approach used in this study provides a deeper mechanistic understanding of the stress responses of organisms exposed to heat stress; however, these analytical techniques may be combined or used independently to measure stress in marine organisms in the laboratory or in the field, which can improve health assessments of wild and farmed aquatic organisms.

The early stages of intertidal mussels, including the green-lipped mussel, Perna canaliculus, face both direct and indirect environmental threats. Stressors may influence physiological status and, ultimately, survival. An understanding of the nature of stress experienced is critical to inform conservation and aquaculture efforts. Here, we investigated oxidative stress dynamics in juvenile P. canaliculus in relation to emersion duration (1–20 h) and relative humidity (RH, 29–98%) by quantifying oxidative damage (protein carbonyls, lipid hydroperoxides, 8-hydroxydeoxyguanosine) and enzymatic antioxidants (superoxide dismutase, catalase, glutathione peroxidase and reductase). Mussels held in low RH during emersion experienced severe water loss (>70%), high mortality (>80%) and increased oxidative damage (35–45% increase compared to control conditions), while mussels held at high RH were not impacted, even after 20 h of air exposure. Following re-immersion, reoxygenation stress resulted in further increases in damage markers in mussels that had experienced dryer emersion conditions; protective action of antioxidants increased steadily during the 10 h re-immersion period, apparently supporting a reduction in damage markers after 1–5 h of immersion. Clearly, conditions during emersion, as well as duration, substantially influence physiological performance and recovery of juvenile mussels. Successful recruitment to intertidal beds or survival in commercial aquaculture operations may be mediated by the nature of emersion stress experienced by these vulnerable juveniles.