A Deep Dive with the Dauphin Island Sea Lab
Marine Research at Dauphin Island Sea Lab
The story begins in 1971 when seven Alabama universities and colleges came together to develop a marine science lab for students on Dauphin Island on Alabama’s Gulf Coast. The overarching idea was to consolidate the disparate marine research and educational resources and channel them into a single world-class entity.
Today, the Dauphin Island Sea Lab (DISL) is the centerpiece of marine research in Alabama, serving as a resource for 22 public and private universities. In 2022, the lab welcomed a record 110,000 visitors.
Are bottlenose dolphins of the Northern Gulf of Mexico migratory? Or do they live out their lives within the local waters?
Bottlenose dolphins primarily can be divided into two groups: coastal and offshore. Coastal bottlenose dolphins are often bay, sound and estuary residents who live close to shore and have small home ranges. On the other hand, offshore bottlenose dolphins, or “transients,” may travel along the coast, with some in the Atlantic known to seasonally migrate.
However, the animals in our area are not yet known to be migratory in this way (best documented for higher-latitude beasts). Our work in the Northern Gulf is trying to answer these types of question about local populations, including the extent to which they may be resident or transient, their home ranges, and their movements in Alabama and adjacent waters.
What is the greatest threat to the dolphin population in the Northern Gulf?
Our research here in Alabama has found about half of dolphin deaths in our area are linked to human interactions. In fact, this is the most common single known cause of death in the stranded dolphins we recover. Typical human interactions that may cause death include vessel trauma, drowning due to entanglement, and sharp or blunt force trauma.
Another common threat to dolphins in the northern Gulf of Mexico is low salinity due to freshwater discharge. When dolphins experience prolonged freshwater exposure it can cause skin lesions, physiological imbalances, and ultimately death either directly or via secondary illnesses.
Can you characterize the intelligence of dolphins? Is it similar to that of any other species in the animal kingdom?
This is a difficult question because measuring intelligence is inherently biased (the testing is done by humans on a human scale of judgment). Dolphins are known to have complex communication. They are also able to teach and learn skills, such as surgically depredating fish from lines, and to use of ‘tools’ to forage for food. They’ve been documented using sponges as face protection while foraging among corals in Australia.
Can you characterize the dolphin’s faculty of echolocation?
In short, dolphins echolocate by producing short clicks using two air pockets located near their blowhole that are tuned and directed through their bulbous forehead, which is really a large fat deposit called a melon. When the click bounces off something and comes back to the dolphin, it is received into another fat pad in the lower jaw next to the ear where it then travels to and is interpreted by the brain.
What is a little-known but extraordinary fact about dolphins?
We’ll Give You Three!
1. Dolphins can be aged using their teeth. They have only one set of teeth throughout their lives (unlike humans who have two), and deposit new layers of dentin annually. When an animal dies and strands, we can save some teeth, slice them in half and count the internal growth layer groups—just like counting the rings of a tree.
These layers of organic and inorganic material also record information about the external environment so that we know the conditions in which the animal was living. The really cool aspect of this research—which our lab carries out—is that it allows us to relate the environmental data to specific years of the animal’s life. Also, when we know the time of death, we can relate the layers to specific years in time. This approach allows us to do things like trace exposure to freshwater that might periodically cause stress throughout the animal’s life.
2. All of a dolphin’s skin sloughs every 2 hours—12 times a day!
3. Dolphins have special adaptations to live in saltwater. Their kidneys are “reticulated,” which means that they have many small kidneys clustered together to form one large kidney like a bunch of grapes. This allows them to be extremely efficient in recovering freshwater from their food. Because of this adaptation, dolphins do not need to directly drink freshwater.
Extra bone fact! Dolphins have ossified sternal ribs. In humans, we have cartilage that connects the tips of our ribs to our sternum. In dolphins, these connections are ossified with bone and provide additional hinges in the dolphin ribcage to allow contracting for deep diving.
A note on reporting marine mammals in distress:
For marine mammals in the Southeastern United States: Please report manatees, whales, and dolphins in distress or stranded at 1-877-WHALE-help (1-877-942-5343). Callers can select the specific state for their report. Specifically for manatees: In Florida, please report to the Florida Fish and Wildlife Conservation Commission (FWC) at 1-888-404-3922. In Mississippi and Alabama: Please report to Dauphin Island Sea Lab’s Manatee Sighting Network at 1-866-493-5803
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