Abstract— Enrichment of live food for marine fish larvae with highly unsaturated fatty acids (HUFA) has been shown to improve survival, growth and stress resistance in many species and to decrease pigmentation abnormalities in flatfish. In order to aid the developing summer flounder industry, we conducted an experiment in which summer flounder larvae were fed diets differing in HUFA composition to determine whether enrichment with a commercially available product would increase survival and growth and reduce the incidence of abnormal pigmentation. We also examined whether growing unenriched rotifers on different species of algae would affect the survival, growth and pigmentation of the flounder larvae to which they were fed. Growth of summer flounder larvae was significantly better when they were fed HUFA‐enriched Mtifers and Artemia rather than unenriched and, among the unenriched treatments, was significantly better when the larvae were fed rotifers raised on Isochrysis galbana rather than on Tetraselmis suecica. The percentage of larvae that failed to complete metamorphosis during the experiment was significantly higher in the unenriched treatments than in the enriched treatments. Neither survival nor percentage of individuals with pigmentation abnormalities were significantly different among the treatments.

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Human usage of coastal water bodies continues to increase and many invertebrates face a broad suite of anthropogenic stressors (e.g., warming, pollution, acidification, fishing pressure). Underwater sound is a stressor that continues to increase in coastal areas, but the potential impact on invertebrates is not well understood. In addition to masking natural sound cues which may be important for behavioral interactions, there is a small but increasing body of scientific literature indicating sublethal physiological stress may occur in invertebrates exposed to high levels of underwater sound, particularly low frequency sounds such as vessel traffic, construction noise, and some types of sonar. Juvenile and sub-adult blue crabs (Callinectes sapidus) and American lobsters (Homarus americanus) were exposed to simulated low-frequency vessel noise (a signal was low-pass filtered below 1 kHz to ensure low-frequency content only) and mid-frequency sonar (a 1-s 1.67 kHz continuous wave pulse followed by a 2.5 to 4.0 kHz 1-s linear frequency modulated chirp) and behavioral response (the animal’s activity level) was quantified during and after exposure using EthoVision XT™ from overhead video recordings. Source noise was quantified by particle acceleration and pressure. Physiological response to the insults (stress and recovery) were also quantified by measuring changes in hemolymph heat shock protein (HSP27) and glucose over 7 days post-exposure. In general, physiological indicators returned to baseline levels within approximately 48 h, and no observable difference in mortality between treatment and control animals was detected. However, there was a consistent amplified hemolymph glucose signal present 7 days after exposure for those animals exposed to mid-frequency sound and there were changes to C. sapidus competitive behavior within 24 h of exposure to sound. These results stress the importance of considering the impacts of underwater sound among the suite of stressors facing marine and estuarine invertebrates, and in the discussion of management actions such as protected areas, impact assessments, and marine spatial planning efforts.