By Brandon L. Southall, Ph.D., SEA & University of California, Santa Cruz
The ocean’s living soundscape reflects teeming life, wild weather, and the deep rumbling of the Earth’s movement. As discussed in my 2 November article, https://www.tpgonlinedaily.com/noisy-ocean-getting-noisier/ humans are newcomers to this scene but have increasingly added various noises. Some sources are loud and intermittent – others are less intense but chronic around ports and population centers.
How these may negatively effect marine life, especially marine mammals, has been the subject of much research, debate, and regulatory and conservation interest, increasingly so in recent decades. These are complex questions with local, national, and global implications.
We are fortunate to have world-class researchers here in Monterey Bay studying how these amazing animals perceive their environment, behave naturally, and respond to disturbances, including noise. Some work in controlled laboratory settings. Others study wild animals with increasingly sophisticated multi-sensor tools. Still others use mathematical models to predict consequences of disturbance for animal populations.
The University of California, Santa Cruz has long been a leader in studying marine mammals, both at Long Marine Laboratory and around the world. For instance, Dr. Colleen Reichmuth, a research biologist at the Institute of Marine Science, Pinniped Cognition and Sensory System Laboratory http://pinnipedlab.ucsc.edu studies hearing, visual, and tactile (“feel”) systems in seals and sea lions. Her team carefully measures how these amphibious mammals perceive sounds in quiet conditions, below and above water. Animals are trained to voluntarily participate in hearing studies, telling us what they hear by pressing a paddle, much like elementary school children in hearing screening tests. This allows Colleen and colleagues to measure how they hear and how noise can affect them.
Local researchers are using new technologies to measure marine mammal behavior in the field. Dr. Jeremy Goldbogen of Stanford University’s Hopkins Marine Station has pioneered multi-sensor data sampling and analytical methods using tags attached to individual marine mammals. His collaborative studies http://goldbogen.stanford.edu/ have shown detailed features of feeding strategies and behavioral changes in response to noise using high resolution movement sensors, simultaneous acoustic measurements of prey, and even high-definition videos from cameras riding on the backs of whales.
With many other colleagues, we’ve been applying these and other tools in a multi-disciplinary research team studying behavior and the effects of noise, including military sonar, on marine mammals in the Channel Islands www.socal-brs.org. The U.S. Navy has supported this research to better understand potential negative effects of their sonars. We have discovered many exciting new aspects of behavior in almost a dozen species, including that many animals clearly respond to such sounds, but their responses depend on the species tested, their behavior at the time, and contextual factors including distance from sound sources.
Many of the broader questions are moving from how individual behavior changes to how disturbance could negatively affect populations. Dr. Dan Costa’s long-standing research program at UC Santa Cruz studies the movement, foraging ecology, and energetics of various marine animals http://costa.eeb.ucsc.edu/. His work integrates aspects of feeding, reproduction, and survival for different species and what levels of disturbance would be required to result in population consequences.
These and other local researchers in our Monterey Bay hotbed of marine science are doing amazing science with local and global implications, increasing our understanding of how animals make, perceive, and respond to noise. Our appreciation has matured beyond more extreme concerns about dramatic loud events to an appreciation for more subtle kinds of responses and what they tell us about responsibly managing our activities in the ocean to ensure we continue to conserve these remarkable animals.