As part of the Deepwater Horizon Oil Spill Natural Resource Damage Assessment in the Gulf of Mexico, we conducted a large passive acoustic survey across the eastern Gulf continental shelf edge to assess impacts to sperm whale population. In the months immediately after the spill, sperm whale occurrence was significantly higher in areas closest to the spill. Over the following seasons in 2010–2011, we documented cyclical patterns of decreased and increased occurrence suggesting that this population exhibits a seasonal occurrence pattern in the region, with seasonal movements to other regions, and not likely directly influenced by the oil spill. Unfortunately, a lack of adequately scaled, pre-spill data on sperm whales, along with limitations on the survey duration constrain our ability to infer spill-related changes in sperm whale occurrence. However, our study establishes post-disaster baseline data for continued monitoring, and an expanded study design could provide a model for continued monitoring.

Cadmium (Cd) is a non-essential environmental endocrine-disrupting compound found in water and a potential threat to aquatic habitats. Cd has been shown to have various short-term effects on aquatic animals; however, evidence for long-term effects of Cd on vocal communications in amphibians is lacking. To better understand the long-term effects of low-dose Cd on acoustic communication in amphibians, male Xenopus laevis individuals were treated with low Cd concentrations (0.1, 1, and 10 μg/L) via aqueous exposure for 24 months. At the end of the exposure, the acoustic spectrum characteristics of male advertisement calls and male movement behaviors in response to female calls were recorded. The gene and protein expressions of the androgen receptor (AR) were determined using Western blot and RT-PCR. The results showed that long-term Cd treatment affected the spectrogram and formant of the advertisement call. Compared with the control group, 10 μg/L Cd significantly decreased the first and second formant frequency, and the fundamental and main frequency, and increased the third formant frequency. One and 10-μg/L Cd treatments significantly reduced the proportion of individuals responding to female calls and prolonged the time of first movement of the male. Long-term Cd treatment induced a downregulation in the AR protein. Treatments of 0.1, 1, and 10 μg/L Cd significantly decreased the expression of AR mRNA in the brain. These findings indicate that long-term exposure of Cd has negative effects on advertisement calls in male X. laevis.