CCBW volunteer, Jennifer Curley, is a Plymouth resident and a 2012 graduate from Arcadia University in Pennsylvania. She writes about sea turtles in Cape Cod Bay, and potential impacts caused by nuclear power plants.

Cape Cod Bay and Sea Turtles

All six sea turtle species found in U.S. waters are listed as either endangered or threatened under the Endangered Species Act. Sea turtles thrive in warmer waters, and they migrate up north in and around Cape Cod Bay during summer months. However, sea turtles in this area don’t come to shore unless they are in need of help, often washed up because they are sick, hurt, or cold-stunned and cannot swim against the tides. When these turtles attempt to head south, they are often trapped in the Bay due to cold-stunning. So far this fall, 225 turtles have been found along the shore – the second biggest stranding year since Massachusetts Audubon’s Wellfleet Bay Wildlife Sanctuary began keeping track of this phenomenon in the 1980’s.

What exactly is cold-stunning? Cold-stunning is the term used to describe what happens after sea turtles are exposed to cold temperatures for an extended amount of time resulting in extreme lethargy, immobility, and oftentimes death. Unlike humans, sea turtles regulate their body temperatures based on external sources, which is why they migrate seasonally to different climates. At the end of November, more than ten Kemp’s Ridley sea turtles began rehabilitation at the National Marine Life Center (NMLC) in Buzzard’s Bay for treatment, according to a blog post on NMLC’s website. All of the turtles were found stranded on Cape Cod over a span of one month, and all suffered from cold-stunning or severe hypothermia. First rescued by Massachusetts Audubon’s Wellfleet Bay Wildlife Sanctuary, they were then treated with emergency care at the New England Aquarium. They will continue their care at NMLC for 5-10 months. These turtles were the lucky ones, since many of the 225 turtles stranded this fall were found dead.

U.S. Fish and Wildlife Service - Northeast Region

U.S. Fish and Wildlife Service – Northeast Region

Sea Turtles and Nuclear Power Plants

The large-scale stranding of cold-stunned sea turtles in Cape Cod Bay is almost always attributed to the shape of the bay – the “hook” of Cape Cod trapping the animals. But could industrial thermal pollution – specifically related to the Pilgrim Nuclear Power Station – play a role as well?

Since Pilgrim has been in operation, it has used up to a half-billion gallons of water from Cape Cod Bay daily for its once-through cooling system. After this water is cycled through the system, the water is discharged back into the bay 32 degrees F hotter. Approximately four times a year, thermal backwash operations clean out pipes and screens that are clogged with various marine life – up to 255 million gallons of water per day is heated to about 120 degrees F during these operations. Based on outdated studies, Entergy reports that Pilgrim creates a 5-mile thermal plume in the Bay – but it could be bigger.

Could turtles be attracted to these waters that are warm but contaminated with radionuclides, metals, and toxic chemicals? There is evidence from investigations at other nuclear plants that this occurs. However, there have not been studies around Pilgrim to investigate whether this could be a problem in Cape Cod Bay. The artificially warm habitat that Pilgrim creates could give sea turtles a false sense of security. It is possible that turtles hang around the artificially warmer waters longer and delay their migration, as evidenced by what has occurred near San Diego Bay’s gas and electric plants, and what is possibly occurring here in Cape Cod. In San Diego Bay, the South Bay power plant heated water to about 79 degrees F in the winters, which kept many turtles nearby. Since its closure, turtles’ migratory patterns have been notably changed according to data collected in the Bay.

Additionally, the environment around nuclear power plants is often “denuded,” or reduced to bare rocks. This is caused by the discharged pollution and existing debris in the water column. The debris is made up of fish, plants, and other organisms that have been sucked into the cooling-system and are killed and torn apart by the reactor condenser system, then reintroduced into the ocean as sediment around the discharge area. This clouds the water and blocks sunlight from reaching the ocean floor, thus killing sea grass and microorganisms essential for marine habitat and the food chain. Since sea turtles migrate to the northeast to feed (primarily on crabs), a healthy food chain is important to sea turtles’ survival.

Another potential problem for sea turtles posed by nuclear plants is impingement and entrainment due to once-through cooling systems. Impingement occurs when turtles and other sea life are pulled against intake screens of large pipes, often resulting in their drowning and suffocation. Entrainment is when smaller sea life is pulled though the screens and into the system. While Entergy’s official statements say they have not found any turtles impacted by their once-through cooling system, other nuclear plants have documented a plethora of turtles impinged and entrained.

This was the case at the Brunswick nuclear plant in North Carolina in 2012, when three turtles were found dead in their canal system. In one year alone, the St. Lucie nuclear power plant in Florida captured 933 sea turtles in their cooling canals, with some dying and being hurt when they were sucked through the pipes.

Injury caused by intake pipe at St. Lucie Nuclear Power Plant. Credit: Coastal Ecology and Conservation Research Group

Injury caused by intake pipe at St. Lucie Nuclear Power Plant. Credit: Coastal Ecology and Conservation Research Group

We hope that Entergy’s reports are correct, and no sea turtles have been impacted (entrained or impinged) by Pilgrim’s once-through cooling system in the past 41 years. However, considering all six sea turtle species found in Cape Cod Bay are federally protected under the Endangered Species Act, and so much time and effort is put in by various organizations and agencies to protect and save these amazing animals, it seems that the issues of thermal pollution, a potentially degraded food supply, and impingement/entrainment in Pilgrim’s once-through cooling system deserves investigation. We hope that when Pilgrims Clean Water Act Permit is updated in 2014 (also known as a NPDES permit; 17 years expired for Pilgrim), that Entergy will be required to not only investigate these issues based on current data, but perhaps even be required to phase out its once-through cooling system. Changing to better technology – a closed-loop system – could better protect sea turtles, as well as all marine life in Cape Cod Bay.

Read more about sea turtles and nuclear power plants →

Sea Turtles and other marine life need our help. If this fall or winter you come across any stranded sea turtles on our Bay’s beaches, please contact these agencies to help:

New England Aquarium: 617-973-5247
National Marine Life Center: 508-743-9888
Wellfleet Bay Wildlife Sanctuary Massachusetts Audubon: 508-349-2615
Provincetown Center for Coastal Studies: 1-800-900-3622

Sources and Additional Reading

1. Brunswick Nuclear Plant to blame for deaths of endangered sea turtles. WWAY NewsChannel 3. May 2012.
2. SEA TURTLE ENTRAPMENT STUDY – ST. LUCIE NUCLEAR PLANT, UNITS 1 AND 2 (TAC NOS. MA6374 AND MA6375). May 2000.
3. Cape Cod Cold Stunning. National Marine Life Center. Nov 2013.
4. Giant Sea Turtles Now Exploring San Diego Bay. The Log. August 2012.
5. License to Kill. NIRS. February 2001.