How does noise impact marine whales?

We all know that it’s difficult for light to transmit in the water, especially in deep water areas. Compared to being in the air on land, the visibility underwater is so low that sight is not that important for creatures living in the water. Therefore, sound has become the only tool they can explore and communicate. Water is a very good conductor of transmission, and sound can travel very long distances in water (Jensen et al., 2009). Many marine mammals, such as whales and dolphins, use sound to see this marine environment. They use the auditory system to discover food, find mates, communicate and explore the surrounding terrain (Peng et al., 2015). However, the increasing amount of anthropogenic noise created below sea level is having a huge impact on whales.

After searching the news and information on the internet, two large whale stranding struck me. One occurred off the coast of the Bahamas in 2000, where about 17 cetaceans were spotted on the shore in two days (Nevala, 2008). The enthusiastic people tried to drive these poor animals back to the open ocean, but they kept swimming back to the shore. Some of the whales unfortunately died. The marine biologists dissected and found that the whales had severe bleeding near their brains. After investigation, it was found that the U.S. Navy’s sonar system had caused a huge, explosion-like sound in the sea, resulting in serious damage to the whales’ hearing system (Nevala, 2008). That’s the reason why these cetaceans wanted to flee away from their habitats. Massive noise altered their behaviors.

There are two classifications of anthropogenic noise. One is impulsive noise like blasting caused by sonar and air guns, and another is stationary noise (Peng et al., 2015). Commercial transportation vessels similarly interfere with whale communication by this kind of low-frequency stationary noise. The communication signals of these mammals are masked and interfered with by the loud noise sound from the ship’s oars, reducing their sensitivity to sound signals (Peng et al., 2015). Without receiving signals that bounce back, young whales may be lost in the ocean, unable to find their families, or even eventually come to their deaths. A defunct auditory system may make it difficult for the whales to find food and miss their mates in the near distance. What sad results these are.

The good news is that industries started to develop quieter ships and enhance the shapes of ships to reduce the noise. Also, with more and more attention on this issue, more policies and requirements have been established for cooperation (Dolman & Jasny, 2015). It is our responsibility to protect the ecological health of the ocean. We should do all we can to reduce the damage and maintain the ecological balance.



Dolman, S., & Jasny, M. (2015). Evolution of Marine Noise Pollution Management. Aquatic Mammals, 41, 357–374.
Jensen, FH., Bejder, L., Wahlberg, M., Aguilar Soto, N., Johnson, M., & Madsen, PT. (2009). Vessel noise effects on delphinid communication. Marine Ecology Progress Series, 395, 161–175.

Peng, C., Zhao, X., & Liu, G. (2015). Noise in the Sea and Its Impacts on Marine Organisms. International Journal of Environmental Research and Public Health12(10), 12304–12323.

Nevala, A. (2008). The Sound of Sonar and the Fury about Whale Strandings. Oceanus.

Fragmentation impact on salamander

I attended a conference activity called Ohio Natural History Conference last weekend and all posters and presentations are super interesting. Among these excellent presentations, one presentation about salamander habitat and population dynamics attracted my attention. The speaker, Dr. Mike Benard, is from Case Western Reserve University and one of the researches his team did was to investigate population dynamics of salamanders under the modification of their habitats, such as habitat loss and new habitat construction. The talk was great and it also invoked me of how fragmented habitats, which means separate habitats, impact salamanders’ reproduction.

Salamanders of Spring | Lake Metroparks

In the presentation, Dr. Benard and his team sampled the population around a wetland where about 75% of the wetland was removed for the construction of a new sewage plant. I expected that the population of salamanders would decrease due to loss of habitat and limited carrying capacity, which means maximum numbers of individuals can be held in one place. However, in contrast, the population of salamanders increased after a slight decrease due to unknown reasons, which represents that the salamanders gave more births within less habitat (Benard 2022).

On the other hand, the abundance of salamanders was estimated in another area that had a history of agriculture and forest fragmentation. These places were altered artificially after agriculture, including less vegetation and less canopy cover existing. Measured the population of local salamanders, the team found out that the abundance here was quite low (Cosentino & Brubaker 2018). The results reflected that vegetation has a negative relationship with the population of salamanders and forest fragmentation could decrease the reproduction of salamanders (Cosentino & Brubaker 2018).

In addition, calculating the risk of local extinction of salamanders, assuming a population isolated from breeding grounds, was used to assess the possible impact of habitat fragmentation in salamanders’ survival. The parameters were calculated using data from the previous 18 years. Their findings revealed a high likelihood of local extinction of the population under habitat fragmentation. It highlighted the grave repercussions of fragmentation (Bar-David et al. 2007). As a result, terrestrial habitats must be protected, and landscape connectivity must be promoted to allow individuals to migrate between breeding locations for potential escape benefits.

In conclusion, the fragmented habitat has various impacts on the population dynamics of salamanders. For example, low vegetation cover would result in low reproduction rates(Cosentino & Brubaker 2018). And isolated populations could show a negative relationship with salamanders’ survivals(Bar-David et al. 2007). The restoration and protection of habitats and connected populations are necessary.





Bar-David, Shirli, Ori Segev, Nir Peleg, Naomi Hill, Alan R. Templeton, Cheryl B. Schultz, and Leon Blaustein. Long-Distance Movements by Fire Salamanders (Salamandra Infraimmaculata) and Implications for Habitat Fragmentation. Israel Journal of Ecology and Evolution 53.2:143-159 (2007).

Benard, M. Ambystoma salamander population dynamics during 11 years of habitat modification and restoration. Ohio Natural History Conference (2022).

Cosentino, B.J., Brubaker, K.M. Effects of land use legacies and habitat fragmentation on salamander abundance. Landscape Ecology 33, 1573–1584 (2018).