Health Assessment Results

We know little about viral diseases in dolphins. Our collaborators are developing state-of-the-art molecular tools to detect viruses and study their impact on marine mammals.

Dive deeper into the science of viral disease

Prior to 2003, only 11 virus species had been reported in all marine mammal species combined. Just in the last three years, calaborating scientists have identified 10 previously unidentified virus species in our dolphins.

This research also has confirmed that humans in close contact with dolphins can be exposed to dolphin viruses and dolphins can catch a virus from humans.

This research was supported by Marine Animal Disease Lab at the University of Florida, and by the Chicago Zoological Society.

Dive deeper into the science of lungworms

Lungworms, are parasites commonly found in the respiratory systems of stranded or dead dolphins. But we know little about how often these parasites occur in healthy wild dolphins, and whether lungworms might be transmitted from mother to calf.

To study this problem, veterinarians collected swabs from dolphin blowholes and samples from their feces. So far, the early evidence suggests the occurrence in wild dolphins is low (only 3%).

Lungworm (Halocercus lagenorhynchi) larvae from a tracheal swab.

It appears that lungworm infections may be transmitted from mother to calf during pregnancy. The impact that such infections may have on calf survival before birth is unknown, but these infections could increase mortality of newborn dolphin calves.

This research was funded by Harbor Branch Oceanographic Institution and supported by the Chicago Zoological Society.

We tend to think of plankton-rich waters as a sign of a productive habitat and as good feeding grounds for whales. But some types of plankton can become a problem for marine animals (and humans nearby) if the plankton population explodes.

Dive deeper into the science of red tide

When this happens in the Sarasota area, it’s called a red tide. The ocean sometimes has a reddish-brown tint because of all the plankton in the water. The plankton causing red tide is called Karenia brevis. The plankton produces a suite of harmful toxins, called brevetoxins, that can build up in fish and cause massive fish kills. Brevetoxins can build up in dolphins that eat the fish, or dolphins can inhale the brevetoxins that occur in the air just above the water’s surface. Brevetoxins also impact manatees, sea birds, and sea turtles.

Fish killed by red tide brevetoxins

Most (76%) of the 21 dolphins stranding in Southwest Florida during 2006-2007 had brevetoxin levels high enough to be detected. In almost one third of these, brevetoxin poisoning was implicated in the animal’s death.

This research was supported by funding from the John H. Prescott Grant Program, Morris Animal Foundation, the Florida Sea Turtle License Plate Sea Turtle Grants Program, and the Chicago Zoological Society.

Antibodies are found in blood or other bodily fluids, and they help the immune system identify and neutralize harmful bacteria and viruses. But little is known about the immune system, or immunology, of dolphins.

Dive deeper into the science of antibodies

Understanding dolphin immunology is critical in the diagnosis, treatment, and management of diseases in captive dolphins, and it’s vital to help nurse sick wild dolphins back to health if they strand. Understanding a dolphin’s immune system helps a veterinarian evaluate the effects of age, infectious diseases, and exposure to toxins.

Because captive dolphins are fed frozen-and-thawed fish and are routinely treated with anti-parasite medications, it is wise to have information for comparison from wild dolphins that likely carry higher parasitic loads.

Funding for this project was provided by Merck Merial Veterinary Scholars, and it was supported by the Chicago Zoological Society.

Researcher takes milk sample

Calves stay with their mothers for 3-6 years, and they may continue to nurse during much of this time.Research conducted from 1988 to 2006 looked at the nutritional value of milk received by dolphin calves, and when calves start catching fish for themselves.

Dive deeper into the science of dolphin milk composition

Results show that calf body weight increased with the percentage of milk fat, and varied inversely with milk water and potassium content in their mother’s milk. There was no significant link between calf survivorship and milk composition.

Blood values from moms and calves caught together suggest that mothers don’t leave their calves to forage for food. If the mother is eating a large meal, the calf is also likely to be ingesting a lot of food.

These results suggest that while continuing to nurse from their mothers at least occasionally, dolphin calves are gradually learning to catch more and more food for themselves. They probably learn about foraging grounds and prey capture techniques from their mothers.

Dive Deeper into the science of dolphin skin disease:

2009 report

2010 update

Lobo’s Disease [Lacaziosis (Lacazia loboi)] occurs naturally only in humans and dolphins. It is a chronic and slow-growing skin disease. It was first observed in dolphins by Randy Wells and  Blair Irvinein 1970.

Lacaziosis lesions observed on FB28 in 2008

This new research is using health assessment data to estimate the prevalence of Lobo’s disease in the Sarasota Bey and Charlotte Harbor dolphin communities.

Graduate student Leslie Burdett Hart is comparing the progression of the disease among four Sarasota Bay resident dolphins that have it, using long-term photographic data. The influence of how genetic, social, and environmental factors that may affect disease progression will also be studied

Funding for this project was provided by NOAA’s Center of Excellence for Oceans and Human Health, Hollings Marine Laboratory, and the Chicago Zoological Society.