Noise Pollution in the Ocean: A Growing Problem

By Rachael Ragen, SRC intern

Marine animals face many forms of pollution, but one of the less obvious forms that has potentially dangerous effects is noise pollution. Humans have always established civilizations near the water, but humans continue to explore further into the ocean and discover new resources. This shift brings a large amount of anthropogenic noise that can be “categorized as high-intensity and acute such as the noise produced by military sonar, pile driving and seismic explorations, or lower-level and chronic such as ship noise.” (Codarin 2009). Sound travels about four times faster in water than making the effects of sound pollution much more pronounced. It often goes unnoticed by humans since the sound of a motor may not be loud above water, but below it can be deafening. This can cause a great amount of stress for animals. Stress can be defined as “a threat to homeostasis” (Romano 2004). This stress can disrupt the normal behaviors of these animals including communication, diving, and hunting.

Cargo Ships [ File:Cargo_Ships_at_Sekondi-Takoradi_Harbour_(Takoradi_Harbour).jpg]

Sound as a form of communication is especially important to the ecology of marine mammals. Many marine mammals live in groups and can be used as part of their social structure or group hunting strategies. It is also often used in locating prey as seen by the bottlenose dolphin and their use of echolocation.

The most extreme example is the response of beaked whales to sonar. There are mass strandings of beaked whales that coincide with military activities. It is believed that these sounds can disrupt normal diving behavior of these whales and cause them to rise much more rapidly. This can lead to gas bubbles in the tissues and the supersaturation of nitrogen in tissues, which could possibly lead to decompression sickness (Rommel 2006). This is likely the cause of death and mass strandings of these organisms. Ear injuries are also common in specimens from mass strandings. Many theories exist on this topic but the definitive cause of the strandings is still unclear.

Beaked Whale [ File:The_True%27s_beaked_whale_

Sensitivity to sound pollution has been shown across many species of marine mammals, including one study by Romano et. al. This study demonstrated the neural-immune response of a white whale and a bottlenose dolphin with the effect of intense sound from a seismic water gun, BEN water gun, and BEN tone. Blood was taken before and after an intense sound and the hormones were analyzed. While there were only two animals used in this study, the results of the blood analysis showed several changes in the immune response. As the study went on the animals began to become desensitized and did not show the same level of stress.

Stress responses have been observed across a wide range of animals besides marine mammals. Fish can communicate vocally, and it has been shown that anthropogenic sounds can greatly decrease the ability of fish to hear each other. Sensitivity was studied in damselfish, brown meagre, and the red-mouthed goby during this experiment. While the effect of the noise changes based on frequency, all species of fish were negatively affected (Codarin 2009).

Damselfish [ _chromis#/media/File:Chromis_chromis_2.jpg]

Noise pollution is a problem for a large variety of marine animals. Further consideration for mitigation measures is required since the long term effects of sound pollution are relatively unknown and could be problematic for many animals. If stress is considered “a threat to homeostasis,” the increased stress levels could lower the ability of their immune system, reproductive success, and many other factors. This could be catastrophic for wild populations if management strategies are not established.

Works Cited

Codarin, A., L. Wysocki, F. Ladich, and M. Picciulina. 2009. Effects of ambient and boat noise on hearing and communication in three fish species living in a marine protected area (Miramare, Italy). 58(12):1880-1887.

Romano, T.A., M.J. Keogh, C. Kelly, P. Feng, L. Berk, C.E. Schlundt, D.A. Carder, and J.J. Finneran. 2004. Anthropogenic sound and marine mammal health: measures of the nervous and immune systems before and after intense sound exposure. Can. J. Fish. Aquat. Sci. 61:1124-1134.

Rommel, S.A., A. M. Costidis, A. Fernandez, P.D. Jepson, D.A. Pabsta, W.A. McLellana, D.S. Houser, T.W. Cranford, A.L. Van Heldenaa, D.M. Allen, and N.B.Barros. 2006. Elements of beaked whale anatomy and diving physiology and some hypothetical causes of sonar-related stranding. 7(3):189-209.

Ingestion of Marine Debris and Sperm Whales

By Jessica Daley, SRC intern

Marine debris is one of the greatest threats facing marine life today. Any man-made, produced, or processed material that is either intentionally or accidentally discarded and finds its way to the ocean is considered marine debris. There are two major hazards to marine life from interactions with debris, entanglement and ingestion (Jacobsen et al. 2010). Entanglement occurs when an animal becomes trapped or wrapped in marine debris and is unable to escape. In some cases this involves discarded nets and other fishing gear, which can ensnare nearby marine life. This is especially dangerous for marine mammals, which breathe air and can drown if they are unable to free themselves (Jacobsen et al. 2010). Some entanglement cases are not lethal, but still severely damage the animal. For example, if a young turtle becomes trapped in a soda-case ring, it may not cause any problems at first. As the turtle grows, however, the ring becomes tighter and tighter on the body, warping the shell and potentially damaging internal organs.

A turtle trapped in a plastic soda ring has grown around the debris, warping its shell. [Leijon, Stefan. “Plastic Turtle.” 29 July 2012.]

Ingestion of marine debris can also be extremely dangerous for sea life. It is not uncommon for dead sea turtles to be found with plastic in their stomachs, because plastic bags resemble the jellyfish that several turtle species feed on (Mascarenhas et al. 2004). Blockage and rupture of the digestive systems are sometimes causes of death, while in other cases the animal starves to death because plastic has no nutritional value but takes up space in the stomach (Mascarenhas et al. 2004).

In the winter of 2016, a study was conducted by Unger et al. on the marine debris found inside 22 sperm whales that stranded and died along the coast of the North Sea (in England, France, the Netherlands, Germany, and Denmark). Prior to this study only 17 cases of debris ingestion had been noted in sperm whales (Unger et al. 2016). Sperm whales are deep-water animals, feeding mostly on squid at depths of more than 1000 meters, but must return to the surface to breathe (Unger et al. 2016). Because they live so deep, it is uncommon for sperm whales to strand. The North Sea is a shallow and variable habitat that is far from ideal for the sperm whale, and has a comparatively high stranding rate on its shores (Unger et al. 2016). Between January 8th and February 24th, 2016, a total of 30 sperm whales stranded along the North Sea. Of these, 22 whales had their gastro-intestinal tracts opened and examined during their necropsies. Seven GTIs were then rinsed and sieved to look for evidence of smaller debris bits. Fecal samples were also taken from 12 of the whales to look for evidence of micoplastics. The thickness of the whales’ blubber was also measured to assess nutritional status.

Nine of the 22 whales were found to have marine debris in their GI tracts, for a combined total of 322 pieces of trash. Of the debris found 78% was assorted fishing gear, including nets, hooks, monofilament fishing line, and rope. The remaining 22% was considered general debris, or anything that was not fishing related. Among the items discovered were a chocolate wrapper, a plastic bucket (broken in half), and a plastic car engine cover. It could not be determined that debris in any of the whales was the cause of death, and all of the whales were found to be in good overall nutritional health. No GI tract lesions or other internal injuries were observed either.

A large net inside the stomach of one of the stranded North Sea sperm whales [Ungar et al.]

A collection of all of the debris found inside a single whale [Ungar et al.]

The high percentage of the whales that had debris in their GI tracts as well as the high number of individual items suggests that sperm whales are more likely to ingest marine debris than other species, but it is not clear if the high volume of trash is partially due to the lack of sperm whales’ normal food source, deep water squids, in the North Sea (Unger et al. 2016). In the 100 years prior to this study only 17 sperm whales had been found with debris in their stomach, and it was assumed that marine debris was of minimal threat to sperm whales. With the results from this study, that proposition appears to be untrue. Although none of the whales showed signs of internal injuries or other complications from the debris inside them, the sheer quantity of material as well as the kinds of debris found are significant reasons for concern. It is not unlikely that if the whales had survived, the debris would have led to complications, such as fishhooks puncturing GI tract lining or netting blocking part of the tract (Jacobsen et al. 2010). In 2008 two sperm whales that stranded in northern California were found emaciated and with a significant amount of debris in their stomachs. One of them also had a ruptured stomach, and the cause of death of both whales could be traced back to the foreign material, which supports the assertion that ingestion of marine debris is dangerous to large cetaceans (Jacobsen et al. 2010).

There is a tremendous amount of evidence that demonstrates how dangerous marine debris is to sea life because of potential entanglement and ingestion. The most effective way to help protect these animals is to limit the amount of trash that enters the ocean, as well as attempting to remove what is already there. The United States alone produced 254 million tons of trash in 2013, and some of that trash inevitably ends up in the ocean (EPA). If you are interested in helping to decrease the amount of debris in the oceans there are many things you can do. Limiting your single-use plastic usage is perhaps the most impactful thing you can do, by doing things like using reusable shopping bags, using metal silverware instead of plastic, not using plastic straws, and using a reusable water bottle (Smithsonian Ocean Team). Beach clean-ups are a great way to help prevent coastal trash from making its way to the ocean. If you are a fisherman, you should avoid cutting and losing nets and monofilament lines so that do not become a potential hazard to animals (Smithsonian Ocean Team). While they may seem like small contributions, they can make a major impact on the lives of marine creatures.

Works Cited

Jacobsen, Jeff K., et al. “Fatal Ingestion of Floating Net Debris by Two Sperm Whales (Physeter Macrocephalus).” Marine Pollution Bulletin, vol. 60, no. 5, 2010, pp. 765–767.

Mascarenhas, Rita, et al. “Plastic Debris Ingestion by Sea Turtle in Paraı́ba, Brazil.” Marine Pollution Bulletin, vol. 49, no. 4, Aug. 2004, pp. 354–355.

“Municipal Solid Waste.” EPA, Environmental Protection Agency,

Smithsonian Ocean Team. “How You Can Help the Ocean.” Ocean Portal | Smithsonian, Smithsonian’s National Museum of Natural History, 27 Dec. 2017,

Unger, Bianca, et al. “Large Amounts of Marine Debris Found in Sperm Whales Stranded along the North Sea Coast in Early 2016.” Marine Pollution Bulletin, vol. 112, no. 1-2, 2016, pp. 134–141.

The Effect of Hurricane Hermine on Black Sea Bass

By Delaney Reynolds, SRC intern

Figure 1: Best Track Positions for Hurricane Hermine. This map is a composite of the best predicted tracks of Hurricane Hermine between August 28th and September 3rd, 2016. Offshore of western Florida, it transformed from a tropical storm to a hurricane, making landfall as a category one hurricane, and then transitioning back into a tropical storm as it made its way across the state into the eastern waters off Maryland. (Source: Berg 2017).

In September of 2016, Hurricane Hermine struck Florida as a category one hurricane and then migrated through Georgia, South Carolina, North Carolina, and then to offshore Maryland. According to the National Oceanic and Atmospheric Administration (NOAA) National Centers for Environmental Information (NCEI), Hermine’s damage “totaled around $550 million, with a 90% confidence interval of +/- $150 million” and demolished 1,600 homes and businesses (Berg 2017). But how did it affect offshore fish populations? Researchers from the University of Maryland designed an experiment to find out.

Four months before Hermine hit Florida, 45 black sea bass were acoustically tagged and acoustic receivers were moored in the shelf waters of three different sites off Maryland; a northern, middle, and southern site. Rash winds of Hurricane Hermine caused destratification, “a process in which the air or water is mixed in order to eliminate stratified layers of temperature, plant, or animal life,” in the water column of the Mid-Atlantic Bight.  Due to this disarrangement, temperatures of northern and middle experimental sites rose 10 degrees Celsius in just ten hours creating an unsuitable environment for living organisms and, thus, either migration or death of the black sea bass was expected.

Figure 2: Black Sea Bass Population Size, Summer 2016. This graph exhibits the decay in population size of black sea bass between the three experimental sites. The two vertical, black, hash-marked lines indicate September 2nd – 6th.  All three experimental sites showed a decline in black sea bass populations and by January of 2017, all three populations had diminished completely. (Source: Secor et al. 2017).

Researchers discovered that 40% of the sea bass populations had evacuated the experimental sites in search of a more suitable habitat and any that stayed behind exhibited decreased activity levels showing that there were large behavioral changes due to the increased temperatures. Evacuation was found to be highest in the northern and southern sites and lower in the middle site and in most cases, migration was permanent. Although some recovery was indicated in the two weeks following Hermine, water column stratification and black sea bass population sizes did not return to normal (Secor et al. 2017).

Although hurricanes are just one of the factors contributing to the emigration of fish species, as our planet continues to warm, hurricanes are predicted to become more intense and more frequent potentially leading to even larger emigration phenomena which would ostensibly take a large toll on the fishing industry. According to the Fisheries Economics of the U.S. 2011 report, recreational fishing in the South Atlantic generates 52,000 jobs and adds $3 billion to the United States’ GDP (Back in Black). Due to their importance to our economy and the threats that they face, it will be imperative to monitor black sea bass and fisheries to ensure that measures are being taken to stabilize the economy when their performances decline.

Works cited

Berg, Robbie. “Hurricane Hermine.” National Hurricane Center Tropical Cyclone Report, 30 Jan. 2017.

Secor, D. H., Zhang, F., O’Brien, M. H., & Li, M. (2018). Ocean destratification and fish evacuation caused by a Mid-Atlantic tropical storm. ICES Journal of Marine Science.

USA Department of Commerce, 27 Sept. 2013. “Back in Black: Black Sea Bass Stock Is Rebuilt.” Accessed from:

Combining hard-part and DNA analyses
of scats with biologging and stable isotopes can reveal different diet compositions and feeding strategies within a fur seal population

By Nicole Suren, SRC intern

Diet analysis of top predators is important in the study of ecology because it can help to illuminate the energetics and ecological interactions of that predator. One method of studying diet is using hard part analysis and DNA barcoding using the animals’ scats, while other methods include stable isotope analysis from blood plasma and an examination of behavior using satellite telemetry. Jenniard-du-Dot et al aimed to compare the effectiveness of these methods, and compile data from all four to obtain a full picture of the diets of 98 lactating females in an Alaska colony of fur seals. The hard part analysis consisted of straining the hard parts out of the seal scat and identifying the prey items they belonged to, and the DNA barcoding utilized the matrix of the scat to isolate the DNA of the various prey items. The two scat analyses were generally in agreement, with the more general classifications obtained from the hard part analysis confirmed and further specified by DNA analysis. While this information was useful, it only included data on what the seals had eaten in the last one to two days. To obtain longer-term data, the researchers used stable isotope analysis from blood plasma, which would give insight into the trophic level the seals had been feeding from for the previous one to two weeks. Finally, the seals were fixed with satellite tags for two months to examine where they were going to forage and what they might be eating there.

Results of the scat analyses. The percentage of the diet of the population of fur seals of many different species confirmed by hard part analysis and DNA barcoding are shown (Jeanniard-du-Dot, Thomas, Cherel, Trites, & Guinet, 2017).


Results of the stable isotope analysis. Levels of carbon (x-axis) and nitrogen (y-axis) isotopes show two trophic clusters, one signifiying an oceanic (pelagic) diet, and one showing a neritic (inshore) diet.

The overall conclusions were that there were two separate foraging strategies within the population: neritic (inshore) foragers and offshore foragers. While the scat analyses may have hinted at this by identifying some exclusively offshore species in the seals’ diets, the other two methods illuminated this phenomenon. The stable isotope analysis identified the inshore trophic levels versus the offshore trophic levels in the respective individuals, and the satellite telemetry showed two distinct foraging patterns, shown in figure 3.

The foraging tracks of 20 satellite tagged fur seals show two distinct foraging patterns.

These findings are not only important in building the life histories of an Alaskan population of fur seals. They support some previous research demonstrating that generalist feeders are often made up of subsets of specialist individuals. Furthermore, they demonstrate the importance of mixed methods in ecology, and how using different methods to examine different timescales and aspects of the life history trait being examined (like combining direct diet analysis and behavior) results in a very thorough study that gives the trait a wider ecological context.

Works cited

Jeanniard-du-Dot, T., Thomas, A. C., Cherel, Y., Trites, A. W., & Guinet, C. (2017). Combining hard-part and DNA analyses of scats with biologging and stable isotopes can reveal different diet compositions and feeding strategies within a fur seal population, 584, 1–16.

Spatial Dynamics as an Approach to Fisheries Management

By Casey Dresbach, SRC intern

In the last half of the century alone, industrial fisheries have witnessed a global increase in total fishing efforts (Anticamara et al., 2011). Fishing efforts include, but are not limited to: the number of organisms caught, the type of gear used, and the areas in which fish are extracted. Implementation of spatial dynamics into fisheries management will afford us a greater comprehension of the direction of the global fishing sector from the perspective of sustainability. It involves the understanding of fishing effort in space and time.

The success of spatial dynamics can be seen in industrial fisheries, specifically those in developed countries. Utilization of vessel monitoring systems, a fairly recent technological advancement, permits the tracking of fishers through live space and time. Spatial information can help managers discern areas of overlap, where fishing practices may be too high in a vulnerable area important to threatened marine species (Rosenberg, 2000).

It is critical to take small-scale fisheries around the world into account when estimating a total global catch. In the developing world, small-scale fisheries are the driving force of the economy and, because of this, have significant impact on the total number of fish caught each year. Nearly removing close to 22 million tonnes, (48.5 billion pounds) per year. Unfortunately, unlike the technology that is readily available in the United States, these decentralized countries are limited. They tend to be spread along the coastline, occur in regions with limited funds or stable governance, and overall have data-poor knowledge with regards to estimating long-term fishing efforts (FAO, 2015).

These small-scale fisheries implement almost an “inherited sense of knowledge,” using what is called local-ecological knowledge (LEK) to support proper management in these fisheries, which is not entirely beneficial in terms of adapting with the rest of the world’s technological advancements.

In a recent study, spatial dynamics were used to assess a small-scale fishery in the Philippines (Selgrath, J. C., Gergel, S. E., and Vincent, A. C. J. 2017). A defined location was chosen, as well as a specified time frame from 1960-2010. The Danajon Bank ecosystem in the Central Visayas, Philippines houses an important double barrier coral reef ecosystem. The study quantified spatial and temporal changes there, in a province with extreme poverty and poor infrastructure. Their small-scale fishery is of vital importance to the highly-populated area. Through participatory mapping and interviews, researchers analyzed the direction of fishing practices and the dramatic shift from fishermen and members of the community who have been exposed to it for the past several years.

Figure 1. Danajon Bank, a double barrier reef located off the northwest coast of Bohol, Philippines.  (The Fisheries and Coastal Resource Management Interpretive Center (FCRMIC))

From these 391 interviews, information was systematically collected about the spatial history of the study area in six specific steps: personal history, fishing history, gear history, orienting fishers to the map, mapping fishing grounds, and fishing ground history. This approach combined historical experience and expertise to create multifaceted timelines and maps of local practices or environments, as shown in Figure 2.  The study also established the evolution of fishing gear practices and further classification of them as destructive or non-destructive, relative to the time. For example, in 1960 this spatial dynamic approach was able to discern that hook-and-line fishing was the predominant fishing gear, used in about 10% of the study area. While at the same time, traps were less than 5% of the study area until the 1970s, when the gear became more prolific.

Figure 2. Along the Danajon Bank Ecosystem in the Philippines, residents were interviewed and asked to map the history of their fishing practices inside of a mapped area. (Selgrath, J. C., Gergel, S. E., and Vincent, A. C. J. 2017)

​The multifaceted participatory mapping of the area over the past fifty years showed in great detail how small-scale fisheries have changed drastically. The study demonstrates how spatial dynamics and historical maps can lead to better-informed policies in data-poor systems (Selgrath, J. C., et al., 2017). A supporting study stated while “scaling up management interventions can make both biological and institutional sense, there is a point at which institutional capacity is exceeded.” (Christie, Pollnac, Oracion, Sabonsolin, Diaz, & Pietri, 2009). The need to immediate policy implementation is important, but deeper evaluations and historical mapping prior can help create a stronger framework of conservatory policy.

​Moving forward, more research is needed to analyze the importance of historical mapping and to better understand a fishery’s status. “The match between the spatial range of the ecosystem and the governance system is the most important consideration and will play an important role in scaling up of fisheries management initiatives.” (Armada, White, et. al 2009). A collaborative method among small-scale fisheries and larger industrial industries should be established in order to optimize an accurate estimate of long term fishing efforts on the global scale; gathering knowledge from a more personal level to better understand the broader impacts.

Works Cited

Armada, N., White, A. T., Christie, P., & Global Marine Time, T. N. (2009, April 17). Managing Fisheries Resources in Danajon Bank, Bohol, Philippines: An Ecosystem-Based Approach. Coastal Management , 308-330.

Anticamara, J. A., Watson, R., Gelchu, A., and Pauly, D. 2011. Global fishing effort (1950–2010): trends, gaps, and implications. Fisheries Research, 107: 131–136. Elsevier B.V.

FAO. 2015. Voluntary guidelines for securing sustainable small-scale fisheries in the context of food security and poverty eradication. FAO, Rome.

Christie, P., Pollnac, R. B., Oracion, E. G., Sabonsolin, A., Diaz, R., & Pietri, D. (2009, April 17). Back to Basics: An Empirical Study Demonstrating the Importance of Local-Level Dynamics for the Success of Tropical Marine Ecosystem-Based Management. Coastal Management , 349-373.

Selgrath, J. C., Gergel, S. E., and Vincent, A. C. J. 2017. Incorporating spatial dynamics greatly increases estimates of long-term fishing effort: a participatory mapping approach. – ICES Journal of Marine Science, doi:10.1093/icesjms/fsx108.

The Fisheries and Coastal Resource Management Interpretive Center (FCRMIC). (n.d.). Danajon Bank. Philippines.

Family Bythograeidae: Highly Specialized Crabs

By Rachael Ragen, SRC intern

The Family Bythograeidae are marine crabs that live near thermal vents. Most of them are colorless, but some may be yellow in color. The eggs and megalopa, which is a post-larva stage of the crab, tend to be orange or red. This coloration is likely due to carotenoids produced by hydrothermal vent bacteria, on which the crabs may be preying. Bythograeidae crabs are influenced by their environment including gametogenesis, which is part of the reproduction process for crabs. As different biological factors in their surroundings fluctuate, the size of oocyst and the rate of gametogenisis also changes. Their climate is therefore incredibly important to their survival.

Bythograeidae crab [Leignel, V., L. A. Hurtado, and M. Segonzac. “Ecology, adaptation, and acclimatisation mechanisms of Bythograeidae Williams, 1980, a unique endemic hydrothermal vent crabs family: current state of knowledge.” Marine and Freshwater Research, 2018, 69, 1-15.]

Hydrothermal vents present a very extreme habitat since they are located in deep sea environments and thermal vents release hot clouds full of chemicals. These crabs must withstand a high pressure climate of about 125 atm and a low temperature of about 2 to 25ºC. The environmental factors also tends to fluctuate frequently. In response to the fluctuations in their surroundings, these crabs are osmoconformers, meaning they can handle changes in salinity. Despite the importance of their environmental factors, there is not a distinct pattern in biogeography.

hydrothermal vent []

As a result of their harsh living conditions, these crabs have developed many specialized behaviors. Since hydrothermal vents release a large amount of chemicals, these crabs must actively remove chemicals from their system. They are also able to handle higher metal concentrations due to episymbiotic bacteria, which has a symbiotic relationship with the crabs and lives on their shell, which aids in detoxification. Studies have shown that the crucial factor for these crabs is temperature and suffer once past their ideal range.

Works Cited:

Leignel, V., L. A. Hurtado, and M. Segonzac. “Ecology, adaptation, and acclimatisation mechanisms of Bythograeidae Williams, 1980, a unique endemic hydrothermal vent crabs family: current state of knowledge.” Marine and Freshwater Research, 2018, 69, 1-15.