Toxins in Marine Mammals: a Story

By: Alexa Kownacki, Ph.D. Student, OSU Department of Fisheries and Wildlife, Geospatial Ecology of Marine Megafauna Lab

As technology has developed over the past ten years, toxins in marine mammals have become an emerging issue. Environmental toxins are anything that can pose a risk to the health of plants or animals at a dosage. They can be natural or synthetic with varying levels of toxicity based on the organism and its physiology. Most prior research on the impacts toxins before the 2000s was conducted on land or in streams because of human proximity to these environments. However. with advancements in sampling methods, increasing precision in laboratory testing, and additional focus from researchers, marine mammals are being assessed for toxin loads more regularly.

A dolphin swims through a diesel slick caused by a small oil spill in a port. (Image Source: The Ocean Update Blog)

Marine mammals live most of their lives in the ocean or other aquatic systems, which requires additional insulation for protection from both cold temperatures and water exposure. This added insulation can take the form of lipid rich blubber, or fur and hair. Many organic toxins are lipid soluble and therefore are more readily found and stored in fatty tissues. When an organic toxin like a polychlorinated biphenyl (PCB) is released into the environment from an old electrical transformer, it persists in sediments. As these sediments travel down rivers and into the ocean, these toxic substances slowly degrade in the environment and are lipophilic (attracted to fat). Small marine critters eat the sediment with small quantities of toxins, then larger critters eat those small critters and ingest larger quantities of toxins. This process is called biomagnification. By the time a dolphin consumes large contaminated fishes, the chemical levels may have reached a toxic level.

The process by which PCBs accumulate in marine mammals from small particles up to high concentrations in lipid layers. (Image Source: World Ocean Review)

Marine mammal scientists are teaming with biochemists and ecotoxicologists to better understand which toxins are more lethal and have more severe long-term effects on marine mammals, such as decreased reproduction rates, lowered immune systems, and neurocognitive delays. Studies have already shown that higher contaminant loads in dolphins cause all three of these negative effects (Trego et al. 2019). As a component of my thesis work on bottlenose dolphins I will be measuring contaminant levels of different toxins in blubber.  Unfortunately, this research is costly and time-consuming. Many studies regarding the effects of toxins on marine mammals are funded through the US government, and this is where the public can have a voice in scientific research.

Rachel Carson examines a specimen from a stream collection site in the 1950s. (Image Source: Alfred Eisenstaedt/ The LIFE picture collection/ Getty Images.)

Prior to the 1960s, there were no laws regarding the discharge of toxic substances into our environment. When Rachel Carson published “Silent Spring” and catalogued the effects of pesticides on birds, the American public began to understand the importance of environmental regulation. Once World War II was over and people did not worry about imminent death due to wartime activities, a large portion of American society focused on what they were seeing in their towns: discharges from chemical plants, effluents from paper mills, taconite mines in the Great Lakes, and many more.

Discharge from a metallic sulfide mine collects in streams in northern Wisconsin. (Image Source: Sierra Club)

However, it was a very different book regarding pollutants in the environment that caught my attention – and that of a different generation and part of society – even more than “Silent Spring”. A book called “The Lorax”.  In this 1972 children’s illustrated book by Dr. Seuss, a character called the Lorax “speaks for the trees”. The Lorax touches upon critical environmental issues such as water pollution, air pollution, terrestrial contamination, habitat loss, and ends with the poignant message, “Unless someone like you cared a whole awful lot, nothing is going to get better. It’s not.”

The original book cover for “The Lorax” by Dr. Seuss. (Image source: Amazon.com)

Within a decade, the US Environmental Protection Agency (EPA) was formed and multiple acts of congress were put in place, such as the National Environmental Policy Act, Clean Air Act, Clean Water Act, and Toxic Substances Control Act, with a mission to “protect human health and the environment.” The public had successfully prioritized protecting the environment and the government responded. Before this, rivers would catch fire from oil slicks, children would be banned from entering the water in fear of death, and fish would die by the thousands. The resulting legislation cleaned up our air, rivers, and lakes so that people could swim, fish, and live without fear of toxic substance exposures.

The Cuyahoga River on fire in June 1969 after oil slicked debris ignited. (Image Source: Ohio Central History).

Fast forward to 2018 and times have changed yet again due to fear. According to a Pew Research poll, terrorism is the number one issue that US citizens prioritize, and Congress and the President should address. The environment was listed as the seventh highest priority, below Medicare (“Majorities Favor Increased Spending for Education, Veterans, Infrastructure, Other Govt. Programs.”). With this societal shift in priorities, research on toxins in marine mammals may no longer grace the covers of the National Geographic, Science, or Nature, not for lack of importance, but because of the allocation of taxpayer funds and political agendas. Meanwhile, long-lived marine mammals will still be accumulating toxins in their blubber layers and we, the people, will need to care a whole lot, to save the animals, the plants, and ultimately, our planet.

The Lorax telling the reader how to save the planet. (Image Source: “The Lorax” by Dr. Seuss via the Plastic Bank)

Citations:

“Majorities Favor Increased Spending for Education, Veterans, Infrastructure, Other Govt. Programs.” Pew Research Center for the People and the Press, Pew Research Center, 11 Apr. 2019, www.people-press.org/2019/04/11/little-public-support-for-reductions-in-federal-spending/pp_2019-04-11_federal-spending_0-01-2/.

Marisa L. Trego, Eunha Hoh, Andrew Whitehead, Nicholas M. Kellar, Morgane Lauf, Dana O. Datuin, and Rebecca L. Lewison. Environmental Science & Technology 2019 53 (7), 3811-3822. DOI: 10.1021/acs.est.8b06487

Olympians in Rio: keep your mouths closed! But what are the resident marine animals to do?

By Leila Lemos, Ph.D. Student, Department of Fisheries and Wildlife, OSU

August 5th was the Olympic games opening date in Rio de Janeiro, Brazil, the city where I am from. The opening ceremony was a big success and everybody seems to be enjoying the sporting events and all of the news that the city is offering. However, behind all the colors, magic and joy of this big event, Brazilians are very unsatisfied about hosting an event like this while the whole country is simultaneously dealing with a big educational, health, political and economic crisis at the moment.

Unfortunately, the crisis also affects the environment and is consequently affecting athletes that are competing in our “carioca” waters. Guanabara Bay, more specifically, where the sailing competitions are taking place, receive waters from more than 50 rivers and streams, as displayed below.

Figure 1: Hydrographic map of the Guanabara Bay region, Rio de Janeiro, Brazil, showing rivers and streams (in blue) that feed into the Bay.
Figure 1: Hydrographic map of the Guanabara Bay region, Rio de Janeiro, Brazil, showing rivers and streams (in blue) that feed into the Bay.

 

Much of the water is not treated and brings sewage and garbage from upstream (Fig.2). Although the government reports that the pollution index in the Bay conforms to national and international standards, and that the areas where competitions are taking place are clean and present no risk to athlete health, public health experts advise athletes to keep their mouth closed whenever they are in contact with the water, as reported by the Independent newspaper (http://www.independent.co.uk/sport/olympics/2016-rio-olympics-water-feces-athletes -mouth-shut-brazil-a7163021.html). The goal was to clean up 80% of the Bay in time for the Olympic games, however this goal was far from achieved and the “solution” was to install barriers to try to avoid waste and untreated sewage reaching the event area.

Figure 2: Pollution contrasting with the beauty of the Sugar Loaf, one of the main tourist attractions in the city. The photo shows the area where competitions are taking place. Source: http://www.insidethegames.biz/articles/1027142/brazilian-politician-accused-of-undermining-effort-to-clean-guanabara-bay-by-publicity-seeking-jump-into-water
Figure 2: Pollution contrasting with the beauty of the Sugar Loaf, one of the main tourist attractions in the city. The photo shows the area where competitions are taking place.
Source: http://www.insidethegames.biz/articles/1027142/brazilian-politician-accused-of-undermining-effort-to-clean-guanabara-bay-by-publicity-seeking-jump-into-water.

 

Bacteria, fecal coliforms and metals occur in the Bay. Professionals from Oswaldo Cruz Foundation (Fiocruz), one of the world’s main public health research institutions, found a drug-resistant bacterium in the Bay waters, which is resistant to antibiotics and may cause multiple infections (https://www.rt.com/news/214807-brazil-olympic-venue-superbug/). Metals like mercury, one of the most toxic metals, can also be found in the Bay and shows long-term effects on marine life of the ecosystem.

Guanabara Bay used to be part of the migratory route of Southern right whales (Eubalaena australis), but unfortunately we do not see the whales in the area anymore. We also do not see turtles any longer and populations of prawns are extremely reduced. On the other hand, mussels, biological indicators of ambient pollution due to their sessile and filter-feeding habits, are continuously proliferating in the Bay. These individuals can accumulate high pollutant levels and are not safe to eat when present in polluted areas. However, local fishermen persist in eating mussels and fish from the Bay.

The Guiana dolphin (Sotalia guianensis) is the only mammal that still frequents the Bay waters and, while about 400 Guiana dolphins inhabited the region in the 80s, currently there are only 34 individuals (http://www.abc.net.au/news/2016-06-27/rio27s-dolphins-need-olympic-effort-to-survive-toxic-waters/7543544). The project MAQUA, responsible for monitoring the dolphins in the Guanabara Bay, correlated the decline of the population with worsening water quality, fishing and noise, as published in an article in “O Globo”, the main Brazilian newspaper (http://oglobo.globo.com/rio/populacao-de-golfinhos-da-baia-de-guanabara-sofre-reducao-de-90-em-tres-decadas-1-16110633).
In this article they presented pictures of dolphins from the Guiana dolphin population in the Bay, including the unfortunate consequences on human interactions (Fig.3).

Figure 3: Guiana dolphins in Guanabara Bay, Rio de Janeiro. A: some of the remaining individuals of Guiana dolphin population from the Guanabara Bay; B: a dolphin plays with a plastic bag; C: a dolphin that suffered an accident with a nylon yarn when young presents a scar across its whole circumference; D: a dolphin exhibit the absence of the pectoral fin. Source: O Globo, 2015 (http://oglobo.globo.com/rio/populacao-de-golfinhos-da-baia-de-guanabara-sofre-reducao-de-90-em-tres-decadas-1-16110633).
Figure 3: Guiana dolphins in Guanabara Bay, Rio de Janeiro. A: some of the remaining individuals of Guiana dolphin population from the Guanabara Bay; B: a dolphin plays with a plastic bag; C: a dolphin that suffered an accident with a nylon yarn when young presents a scar across its whole circumference; D: a dolphin exhibit the absence of the pectoral fin.
Source: O Globo, 2015 (http://oglobo.globo.com/rio/populacao-de-golfinhos-da-baia-de-guanabara-sofre-reducao-de-90-em-tres-decadas-1-16110633).

 

This dolphin population is living in heavily polluted waters caused solely by human behavior. Although dolphins may distinguish between trash and food, they feed on contaminated fish – a consequence of bioaccumulation.

During my master’s degree at the Oswaldo Cruz Foundation in Rio de Janeiro, I undertook a toxicological analysis of different species of dolphins (Lemos et al. 2013; http://www.sciencedirect.com/science/article/pii/S0147651313003370). We found high levels of different metals, such as mercury and cadmium, in animals along the north coast of Rio de Janeiro. Just like the mussels, dolphins bioaccumulate high pollutant levels in their tissues and organs, primarily via feeding, but also through dermal contact. Metals and other pollutants present in polluted waters, like the Guanabara Bay, enter the food chain and affect multiple trophic levels, compromising health.

Dolphins from the Guanabara Bay are feeding on the same prey as the local fisherman, and act as sentinels of the environment, warning of public health concerns for humans. Just like humans, these dolphins are long-lived and large mammals, but they live every day in these waters and must open their mouths to survive. If we are concerned about human athletes spending a few hours in the water, we should be outraged at the conditions we force marine animals to live in daily in the Rio de Janeiro region. The dolphins have the intrinsic right to live in a non-polluted environment and be healthy.