How does noise impact marine whales?

https://www.sciencenewsforstudents.org/article/lets-learn-about-whales-dolphins-cetaceans

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.

 

References

Dolman, S., & Jasny, M. (2015). Evolution of Marine Noise Pollution Management. Aquatic Mammals, 41, 357–374. https://doi.org/10.1578/AM.41.4.2015.357
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.https://www.int-res.com/abstracts/meps/v395/p161-175/

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. https://doi.org/10.3390/ijerph121012304

Nevala, A. (2008). The Sound of Sonar and the Fury about Whale Strandings. Oceanus.https://www.whoi.edu/oceanus/feature/the-sound-of-sonar-and-the-fury-about-whale-strandings/

Hypoxia in the Mississippi River Delta

The Mississippi River Delta is one of the most biologically diverse areas in the United States, teeming with fish, waterfowl, and dense vegetation. The Mississippi River is essential for the maintenance of this estuarine environment, depositing nutrients and sediment into the delta and Gulf of Mexico. However, this mass nutrient deposition causes eutrophic conditions and a large hypoxic zone every year. This “dead zone” can exceed 20,000 square km and can leave potential habitat within the zone uninhabitable.

Hypoxic zone formation is a eutrophication process . Excess nutrients, primarily nitrogen and phosphorus, often enter the river from sources of agricultural runoff and waste. As nutrients flow down the Mississippi River, levels of primary production increase along with organic matter (Rabalais et.al. 2002). Degradation of the organic matter is mostly done by oxygen-consuming microbes which deplete dissolved oxygen.

Excess nutrients and affected primary production have the potential to change the dynamic of an entire ecosystem. One of the most noticeable effects is displacement of aquatic organisms. Fish breathe by buccal pumping where oxygen is filtered out of water by the gills, so depleted oxygen in water decreases survivability, and many swimming organisms cope by simply leaving the hypoxic area (Rabalais et.al. 2002, Bryant 2010). Shifts in partial oxygen can increase the oxygen-binding affinity of hemoglobin. Direct mortality also negatively affects the ecosystem. Fish populations that feed mainly on primary producers increase, while others decrease due to oxygen deficiency and depleted food sources (Rabalais et.al. 2002).

 

References

Rabalais, N. N., R. E. Turner, and W. J. Wiseman. 2002. Gulf of mexico hypoxia, a.k.a. “The dead zone.” Annual Review of Ecology and Systematics 33:235–263.

Bryant, M.D. 2010. Past and present aquatic habitats and fish populations of the Yazoo-Mississippi Delta. Gen. Tech. Rep. SRS–130.

Wildlife Crossings Cross One Risk Off the List

As urbanization spreads and the human population of earth grows, roads and highway systems are expanding to keep up with urban sprawl. It is well known that habitat loss is one of the more detrimental anthropogenic impacts to wildlife. But what about roads specifically can be so harmful to animals? And is there anything we can do to mitigate these impacts?

First of all, the sheer stress that traffic noise elicits can have quite the negative impact. Birds are one unlucky recipient of the brunt of negative effects of roads. Obviously, most birds do not need to cross a busy street on foot and can instead just fly right over. However, birds often have to compete with the loud, low hum of traffic noise when emitting calls to find a mate or defend their territories. Traffic noise has even been shown to cause changes in breeding patterns, increase stress levels, and change how birds interact with their offspring (Halfwerk et al., 2011).

Furthermore, roadways by design fragment wildlife habitat and act as a literal barrier for animals that can prove fatal to attempt to cross on foot. Collisions with vehicles are all too common in cities, as I am sure we all are familiar with seeing an animal laying on the side of the road after an unfortunate encounter with a car or truck. Deer, opossums, squirrels, and even mountain lions (among many other animals) are all examples of creatures who too often meet unfortunate ends while trying to cross a street to find food, a mate, new territory or to escape predation.

So, what can be done to mitigate the impacts roadways have on wildlife? While the impacts from traffic noise are harder to alleviate, there is a solution to help with the fragmentation roads cause and danger associated with attempts to cross them. Enter: wildlife crossings!

Wildlife crossings are exactly what they sound like: a corridor designed to link habitats on either side of a roadway or other barrier, which will help restore landscape connectivity and give wildlife a safe way to cross the street. The first wildlife crossing was built over 60 years ago in Florida. Now, wildlife crossings are often incorporated into early highway planning stages and may even be added as retrofits to existing highways (Clevenger, 2005).

“Wildlife crossing 3” by afagen is marked with CC BY-NC-SA 2.0. To view the terms, visit https://creativecommons.org/licenses/by-nc-sa/2.0/?ref=openverse

Construction has recently started on what will be the world’s largest wildlife crossing, which will span 10 lanes of Highway 101 traffic in Los Angeles. The $87 million project is expected to be completed in 2025 and was primarily designed to give mountain lions a safe way to pass from the Santa Monica mountains, over the freeway, and into the Simi Hills of the Santa Susana mountain range. The population of mountain lions in this area also is suffering from inbreeding and a resulting lack of genetic diversity due to being surrounded by roadways and isolated to their “urban island”, which further underscores the importance of this project (Mossburg, 2022).

California Governor Gavin Newsom has pledged to contribute $50 million to other similar projects around the state (Mossburg, 2022). This project will also likely kick forward other wildlife crossing projects across the country (and perhaps the world). It is time to start incorporating wildlife considerations into our roadway plans to allow for safe passages. Next up, how to deal with all that traffic noise…

 

REFERENCES:

Clevenger AP. (2005) Conservation Value of Wildlife Crossings: Measures of Performance and Research Directions. GAIA 14(2):124-129.

Halfwerk W, Holleman LJ, Lessells CM and Slabbekoorn H. (2011) Negative impact of traffic noise on avian reproductive success. Journal of Applied Ecology 48:210-219.

Mossburg C. (2022, April 25). Construction starts on world’s largest wildlife crossing to let animals roam over 10 lanes of L.A. highway. CNN. Retrieved from https://www.cnn.com/2022/04/23/us/california-wildlife-crossing-scn-trnd/index.html.

“Hey! Turn that light off!” – Sea Turtles and Light Pollution

Sea turtles (Cheloniidae and Dermochelyidae families) are beloved by many, featured in animated kids movies like Finding Nemo as well in many viral videos showing newly-hatched babies scurrying into the ocean. Many people who live near them know they are endangered and care about them. What they don’t know is that their back porch light to their beach house is causing trouble. Artificial light pollution is a relatively new threat for sea turtles, disrupting many of their physiological functions.

Florida’s beaches are where many sea turtle species call home, nesting under the sand in the dunes. As beach tourism in the state continues to grow, more and more artificial light is spreading along the coastline, threatening these nesting sites. The artificial light disrupts the turtle’s circadian rhythm, confusing them if it is nighttime or daytime, making them more vulnerable to nocturnal predators who catch them unaware (Hu et al., 2018). In addition, when baby turtles are hatching, light pollution can disorient them during their dash to the ocean (Long et al., 2022). Geo-spacial collected data shows, however, that sea turtles are already avoiding areas of high light pollution (figure 1). Therefore, continued expansion of lights along Florida’s beaches could continue to reduce usable habitat for sea turtle nesting activities.

Figure 1. Geo-spacial map of artificial light on the Florida coast vs. density of Loggerhead turtle nests (Hu et al., 2018)

Luckily, the people of Florida have the sea turtles backs. Legislation exists that prohibits certain wavelengths of light to be visible from the beach, requiring shielding of exterior light bulbs (Mascovich et al., 2018). Education programs are also conducted to inform tourists who may be staying at a place close to the beach, informing them to turn off their exterior lights at night to protect nests. These programs are conducted with mixed success, however, with guests often still leaving their lights on throughout the night (Mascovich et al., 2018).

New lighting technology has also recently become an idea of preventing further and reducing current light pollution. For example studies show that Loggerhead sea turtles (Caretta caretta) are generally more sensitive to shorter wavelengths of light at less than 560 nanometers (Long et al., 2022). Thus, the state of Florida has been testing a new 624 nanometer lamp to use along coastal highways, to try and reduce light pollution that highways create. A study conducted by Long et al. showed that these new lamps DO work, with hatching turtles finding their way to the ocean just fine (2022).

Overall, while these solutions do work, they are not strictly enforced. There must be more legislative action and encouragement to use higher frequency light near the nesting locations to reduce light pollution.

References:

Hu, Z., Hu, H., & Huang, Y. (2018). Association between nighttime artificial light pollution and sea turtle nest density along Florida coast: A geospatial study using Viirs Remote Sensing Data. Environmental Pollution, 239, 30–42. https://doi.org/10.1016/j.envpol.2018.04.021

Long, T. M., Eldridge, J., Hancock, J., Hirama, S., Kiltie, R., Koperski, M., & Trindell, R. N. (2022). Balancing human and sea turtle safety: Evaluating long-wavelength streetlights as a coastal roadway management tool. Coastal Management, 50(2), 184–196. https://doi.org/10.1080/08920753.2022.2022974

Mascovich, K. A., Larson, L. R., & Andrews, K. M. (2018). Lights on, or lights off? hotel guests’ response to nonpersonal educational outreach designed to protect nesting sea turtles. Chelonian Conservation and Biology, 17(2), 206. https://doi.org/10.2744/ccb-1299.1

Animals are gaining longer appendages in the face of Climate Change

Ectotherms, or animals that regulate their own body heat, have recently been shown having longer legs, tails, or beaks due to increased temperatures (Fearon, 2021). This may seem like a weird adaptation for animals to get on board with, but it makes sense. Endotherms shed heat through their beaks and tails, so having a larger surface area means these animals are able to cool off quicker (Fearon, 2021). Physiologically speaking, as temperatures continue to warm, these individuals will need to find ways to keep their bodies at optimal temperatures because once their body temperatures increase to a certain point they will have other problems to contend with.

Figure 1: The North American dark-eyed junco with a longer then usual beak (modified from Fearon, 2021).

So, as temperatures continue to rise, we may just see more birds like The North American dark-eyed junco showing longer beaks. Or individuals like the Wood Mouse showing longer tails. Or even animals like the Masked Shrew adapting larger legs. So why do we, as humans, care about these changes? It’s important to know that some animals are able to adapt to the quick changes in temperature that we are currently seeing. However, it is important to know that this is not an indication that animals are doing well in the face of climate change (Fearon, 2021). It means they are surviving by adapting in these ways. Climate change is happening quickly, and in most cases, it may be happening too quickly for animals to adapt to (Fearon, 2021).

This is not the only way we see animals adapting to the effects of Climate Change. It is, however, one of the most interesting to see. The adaptations mentioned above are happening at faster rates then we usually see, but they are among the multiple adaptations we will likely be seeing moving forward (Fearon, 2021).

 

References

Fearon, R. (2021). Shape-shifting is how some animals adapt to climate change. Retrieved April 25, 2022, from https://www.discovery.com/nature/shape-shifting-is-how-some-animals-adapt-to-climate-change