Editing Cetacea (section)

=== Environmental hazards ===
{{See also|Marine mammals and sonar}}
{{Quote box|quote=Worldwide, use of active sonar has been linked to about 50 marine mammal strandings between 1996 and 2006. In all of these occurrences, there were other contributing factors, such as unusual (steep and complex) underwater geography, limited egress routes, and a specific species of marine mammal—beaked whales—that are suspected to be more sensitive to sound than other marine mammals.
|source=—Rear Admiral Lawrence Rice|align=left|width=30%}}

Heavy metals, residues of many plant and insect venoms and plastic waste [[flotsam]] are not biodegradable. Sometimes, cetaceans consume these hazardous materials, mistaking them for food items. As a result, the animals are more susceptible to disease and have fewer offspring.<ref name="wdcs" />

Damage to the [[ozone layer]] reduces plankton reproduction because of its resulting radiation. This shrinks the food supply for many marine animals, but the filter-feeding baleen whales are most impacted. Even the [[Nekton]] is, in addition to intensive exploitation, damaged by the radiation.<ref name="wdcs" />

Food supplies are also reduced long-term by [[ocean acidification]] due to increased absorption of increased atmospheric carbon dioxide. The CO<sub>2</sub> reacts with water to form [[carbonic acid]], which reduces the construction of the [[calcium carbonate]] skeletons of food supplies for zooplankton that baleen whales depend on.<ref name="wdcs" />

The military and resource extraction industries operate strong [[sonar]] and blasting operations. Marine seismic surveys use loud, low-frequency sound that show what is lying underneath the Earth's surface.<ref name="Nowacek">{{cite journal|last1=Nowacek|first1=Douglas|last2=Donovan|first2=Greg|last3=Gailey|first3=Glenn|last4=Racca|first4=Roberto|last5=Reeves|first5=Randall|last6=Vedenev|first6=Alexander|last7=Weller|first7=David|last8=Southall|first8=Brandon|title=Responsible Practices for Minimizing and Monitoring Environmental Impacts of Marine Seismic Surveys with an Emphasis on Marine Mammal|journal=Aquatic Mammals|date=2013|volume=39|issue=4 |pages=356–377|doi=10.1578/am.39.4.2013.356|bibcode=2013AqMam..39..356N }}<!--|access-date=April 2, 2016--></ref> Vessel traffic also increases noise in the oceans. Such noise can disrupt cetacean behavior such as their use of [[biosonar]] for orientation and communication. Severe instances can panic them, driving them to the surface. This leads to bubbles in blood gases and can cause [[decompression sickness]].<ref>{{Cite book|author1=M. Andre|title=Europe Oceans 2005|author2=T. Johansson|author3=E. Delory|author4=M. van der Schaar|publisher=Oceans 2005–Europe|year=2005|volume=2|pages=1028–1032 Vol. 2|doi=10.1109/OCEANSE.2005.1513199|chapter=Cetacean biosonar and noise pollution|isbn=978-0-7803-9103-1|s2cid=31676969}}</ref> Naval exercises with sonar regularly results in fallen cetaceans that wash up with fatal decompression. Sounds can be disruptive at distances of more than {{convert|100|km|mi}}. Damage varies across frequency and species.{{citation needed|date=October 2024}}