Sounds of Stress: Assessment of Relationships between Ambient Noise, Vessel Traffic, and Gray whale Stress Hormone

Elevated noise from human activities in nature can impact animal behavior and physiology, with subsequent impacts on individual health and population dynamics. Baleen whale communication, navigation, habitat use, and ability to recognize and locate prey and predators may be impaired by anthropogenic activities that increase ocean noise within the whales' hearing frequency range. To understand the physiological impacts of noise disturbance on baleen whales, we investigated the adrenal stress response of gray whales (Eschrichtius robustus) to variable ambient noise levels through an assessment of fecal glucocorticoid metabolite concentrations. This analysis was conducted at the individual level, at multiple temporal scales (1-7 days), and accounted for factors that may confound glucocorticoid hormone concentrations: sex, age, nutritional status, and reproductive state. Data were collected along the Oregon coast, USA, from June to October of 2016-2018. Results indicate a significant positive correlation between underwater noise levels and vessel traffic. Vessel counts from the day prior to fecal sample collection and sex had significant positive relationships with glucocorticoid metabolite concentrations. This study increases knowledge of gray whale physiological response to variable ocean noise and may inform management decisions regarding regulations of anthropogenic noise activities and thresholds near critical whale habitats.

Seagrass Posidonia is impaired by human-generated noise

The last hundred years have seen the introduction of many sources of artificial noise in the sea environment which have shown to negatively affect marine organisms. Little attention has been devoted to how much this noise could affect sessile organisms. Here, we report morphological and ultrastructural changes in seagrass, after exposure to sounds in a controlled environment. These results are new to aquatic plants pathology. Low-frequency sounds produced alterations in Posidonia oceanica root and rhizome statocysts, which sense gravity and process sound vibration. Nutritional processes of the plant were affected as well: we observed a decrease in the number of rhizome starch grains, which have a vital role in energy storage, as well as a degradation in the specific fungal symbionts of P. oceanica roots. This sensitivity to artificial sounds revealed how sound can potentially affect the health status of P. oceanica. Moreover, these findings address the question of how much the increase of ocean noise pollution may contribute in the future to the depletion of seagrass populations and to biodiversity loss.

Measuring the Pulse of Earth's Global Ocean: Ocean Sound and Marine Life Interagency Working Group

The “Measuring the Pulse of Earth's Global Ocean” project will attempt to quantify sound levels in what should be the quietest parts of the ocean—the five deepest locations—to gauge the baseline level of sound in these remote ocean areas. Ocean noise from human-made sources of sound (e.g., shipping) can have a detrimental effect on marine animals that use sound to sense their environment. Thus noise can negatively impact the health of marine ecosystems, which are the basis for many sectors of the global “Blue” economy, including commercial fisheries and aquaculture. This project will gather unique baseline data to monitor the “acoustic health” of the oceans. A novel, deep-ocean capable hydrophone-lander system will be deployed at each of these five deep-sea sites (all >7 km deep). The project will involve the collaboration of several U.S. governmental agencies, private industry and NGOs, and international partners to access these global locations. We will collaborate with scientists from each of these five sites to deploy, recover, and analyze this deep ocean acoustic data. Our ocean sound program aspires to develop a robust and inclusive education/outreach program, focusing on the impact of underwater noise on the health of marine ecosystems.