L. Henderson \ Oceans First, Issue 2, 2015, pgs. 1-9.
Climate change associated with increasing ocean temperatures is impacting the narwhal population of the Arctic Ocean, an area highly susceptible to rising temperatures. Among other things, these unique cetaceans are being affected by ice-entrapments and top-down controls from killer whale predation. Examining these factors can help predict the dangers to narwhal populations for future conservation efforts. Increasingly delayed ice formation due to global warming is causing high mortality of narwhals as they become entrapped in the rapidly freezing ice of the harsh winter. Warming ocean temperatures are opening up Arctic waters for killer whales to hunt narwhals as well, killing many more than they need for food in the process. The small population of narwhals is especially vulnerable to climate change. The narwhals are an important part of the Arctic food chain, being one of many secondary consumers, and increase its biodiversity with their distinctive protruding tusk, unique to the narwhal only. This review synthesizes the events causing increased mortality rates of narwhals to provide a scope for future conservation efforts.
R. Lung \ Oceans First, Issue 1, 2014, pgs. 12-19.
Studies show increasingly negative effects associated with anthropogenic sound and human disturbance. These negative effects are both behavioural and physiological. The chronic activation of the short-term stress response as a result of increased ship noise potentially has detrimental effects regarding growth, reproduction, immune function, and digestion. Methods to acquire data involving behaviour are mainly observational. To monitor acoustic behaviour, hydrophones are used. The behaviour of cetacean species is altered in the presence of human disturbances such as marine construction, sonar, and ship noise. Their vocalizations are also affected; differing in length, overall presence, and frequency. Mass strandings have occurred as a result of active naval sonar exposure. Naval sonar administers frequencies similar to those of beaked whales, often resulting in acoustic masking. To examine sustained injuries, post-mortem internal examinations are conducted. The sonar signals can have fatal effects, including hemorrhage in multiple organs, gas and fat embolism, and bubble lesions formed as a result of the supersaturation of nitrogen gas within tissues. Future research will enable the determining of more long term effects in relation to anthropogenic sound effects.