Mystic ― In a vast two-story space in Mystic Aquarium’s Milne Center for Ocean Science and Conservation, daily conservation and rescue efforts for horseshoe crabs and sea turtles occur unnoticed by most aquarium visitors.

The Milne Center, which opened in 2019 and houses facilities for research, education, rehabilitation and breeding programs, provided much needed space.

The $10 million facility allowed expansion of the animal rescue program to take in more sea turtles for rehabilitation and space for a horseshoe crab hatching program intended to bolster declining populations.

MaryEllen Mateleska, senior director of education and development, on Thursday gestured through glass windows of the Aquaculture Laboratory, located in the space, at a large shallow tank.

The tank contained five tiny baby horseshoe crabs, which are more closely related to spiders than crabs. They’re part of a program to hatch and nurture the prehistoric creatures until they can be released.

“They are living fossils. They have remained unchanged for 200 million years, if not more, so when you look at fossils, they look the exact same,” she said. “They found a way to survive that fit for them, but we’ve benefited from that as well.”

Locally, the creatures are harvested for bait, but worldwide, they are sought for their unique, blue blood.

The biomedical industry uses the blood to detect endotoxins, a type of bacteria, in humans, medications, and medical equipment like intravenous devices. When the horseshoe blood encounters an endotoxin, the cells break open and form what Mateleska calls a jelly Band-Aid surrounding the bacteria.

The five hatchlings represent hope for the preservation of the animal, whose conservation status is labeled poor by the Atlantic States Marine Fisheries Commission due to dwindling numbers in the wild, which Mateleska attributes to habitat degradation and unregulated bait fisheries.

“In the past, during a survey, we might catch 200 horseshoe crabs in a night; now we are lucky if we see seven. The problem is, there isn’t a lot of migration, so once they’re out of our habitat, it’s not like new ones are going to come in,” said Mateleska.

Though a female can lay up to 80,000 eggs during a May through June nesting season, only one out of 2,000 eggs survives, due to birds, like the endangered Red Knot, that rely on the incredibly dense source of fat and protein for vital nutrition.

“Without them, you will have entire bird species that are on the endangered species list because of that interaction,” she said.

Mateleska will not see the impact of her daily efforts for another 8-10 years, when the babies hatching today finally reach adulthood, but she recognizes the importance of the work she is doing to conserve the species.

Sea turtles

A handful of yards from the lab, Sarah Callan, manager of the animal rescue program, stood at an exam table with a Kemps Ridley Sea Turtle called 120, currently being treated for wounds on the top of his shell caused by frostbite and a bone infection.

New England Aquarium numbers each turtle it rescues, starting from zero each fall. The name 120 indicates this was the 120th turtle rescued during a Thanksgiving weekend “cold-stunning” event, when rapid temperature drops cause the turtles to become hypothermic and wash up on beaches.

Of the four species of sea turtles found locally, only the Leatherback, which can reach 1,000 pounds, is here year-round. Kemps Ridley, Loggerheads and Green Sea Turtles, are seasonal visitors that migrate south as waters cool in the fall.

Callan said drops in temperature have become more abrupt in recent years due to climate change, leaving the turtles less time to find their way around the hooked coastline surrounding Cape Cod Bay, where they feed in warmer months. Many end up cold-stunned.

“They look dead, but if we can detect a heart rate, there’s a good chance we can save them,” she said.

Over Thanksgiving weekend, local organizations stepped in to take some of the hundreds of turtles that washed ashore. Mystic Aquarium accepted 12 of them. Since November, more than 800 turtles have been rescued on Cape Cod.

Callan explained that first responders transporting the turtles must drive with their windows open and without heat to prevent the animals from heating up too quickly. Once at the aquarium, their caretakers slowly raise the water temperature by five degrees a day to approximately 75 degrees, so the turtles do not go into shock.

Callan said the turtles will seem healthy at first, but two to three weeks after rescue, systemic illnesses like pneumonia begin to appear. She said #646, a Loggerhead that came in the first week of December, currently is being treated for it after aquarium veterinarians identified it through x-rays.

If the weather is still cold when the turtles recover, the aquarium uses a network of volunteer pilots with private planes called Turtles Fly Too, to fly the turtles down south to be released.

“It has a huge conservation impact because every single sea turtle that we respond to is threatened or endangered,” Callan said. “Just rehabbing and rescuing one turtle can impact the whole species.”