Understanding the effects of harmful algal blooms

 

Spencer Fire using a small plankton net to collect water samples for analyses during health assessments.
Spencer Fire using a small plankton net to collect water samples for analyses during health assessments.

I joined SDRP in 2003 as a University of California Santa Cruz PhD student with interests in the effects of harmful algal blooms (HABs) on marine wildlife. My research experience prior to joining SDRP was primarily focused on fisheries and human health, and as a true lab nerd, I had never seen a dolphin or spent much time on a boat. During my time with SDRP, I learned a variety of valuable field research skills that allowed me to successfully complete a dissertation investigating the effects of HAB toxins on the Sarasota bottlenose dolphin population. I also became conversant with important issues in marine mammal conservation biology that have served me well and shaped my research interests ever since.

After completing my graduate studies and leaving SDRP in 2006, I was fortunate to land a position with the National Oceanic and Atmospheric Administration (NOAA) due to my experience combining the study of HAB toxins and marine mammals. At the NOAA lab in Charleston, South Carolina, I led a team of scientists who responded to, and provided analytical services for, HAB-related events, most of which involved marine mammal strandings. During this time I continued my fruitful collaboration with my SDRP friends and colleagues, who allowed me back every year for health assessments despite my supernatural ability to disable boat electronics simply by being near them. One highlight of this collaboration was when we jointly published the first case of multiple HAB toxin exposure in live dolphins sampled during the SDRP health assessments.

In 2014, I moved from my role as a federal research scientist into a faculty position at Florida Institute of Technology in Melbourne, Florida. During this past year, I have been able to start my own research program and advise graduate students as we continue to investigate the role of natural toxins in marine mammal food webs. The research we are beginning through FIT focuses on the nearby Indian River Lagoon Estuarine System, a critical habitat along Florida’s Atlantic coast, where HABs and bottlenose dolphins also overlap. Fortunately, our fledgling research program continues to benefit from support, training and collaboration with SDRP staff. With time, we hope our research makes as positive an impact on the Indian River Lagoon dolphins as SDRP has had on their Sarasota Bay counterparts.

This article appeared on page 31 in the December 2015 issue of Nicks n Notches.

Use of overhead imaging for body condition assessment

pole cam, obtaining aerial photos
R/V Challenger, outfitted with the pole cam, obtaining aerial photos of Riptorn. In addition to revealing insights in body condition, this imaging technique also uniquely documented the severity of Riptorn’s scoliosis.

The body or nutritional condition of dolphins can significantly affect individual survival and reproductive success. In addition, it can be a sensitive indicator of prey abundance, feeding success, and the general health of an individual. Thus, assessing the body condition of animals is critical for monitoring the health of dolphin populations. However, current methods of measuring body condition in free-ranging dolphins require capturing, restraining and sampling individuals directly through capture-release health assessments, which are expensive, logistically complex, and are not feasible in many situations.

With a grant from the Association of Zoos & Aquariums Conservation Endowment Fund (through funding from the Disney Worldwide Conservation Fund), and a fellowship grant from the Morris Animal Foundation, we designed and built a low-cost remote controlled unmanned aerial vehicle (UAV) to remotely measure the body condition of dolphins at sea. The six-rotor UAV, which has a digital camera mounted below it, is designed to be launched from a small boat and to hover precisely over individual animals to collect photographs for detailed measurements of body size and shape (a technique called aerial photogrammetry). Initial field testing of the UAV system was conducted in 2014 over dolphins being temporarily held in large net corrals during capture-release health assessments in Sarasota Bay.

Riptorn, his severe case of scoliosis evident
Riptorn, his severe case of scoliosis evident in his peduncle.

More recently, in response to FAA restrictions and uncertainties regarding deployment of UAVs, we have been using a pole-mounted camera system to collect overhead images of Sarasota Bay dolphins. The pole camera was constructed by engineers at Woods Hole Oceanographic Institution under the guidance of Michael Moore. It makes use of a long carbon fiber pole that was previously used to deploy tags on large whales. With the pole camera mounted on the SDRP’s pontoon boat R/V Challenger, we collected overhead images of more than 60 dolphins this summer both during capture-release health assessments and during boat-based surveys while animals were free-swimming in the bay.

Lizzie, Fringes, and calf
Lizzie, Fringes, and calf FRN4, less than a month old.

The images will enable us to compare body size and shape measurements (such as total body length and girth) obtained from the aerial photographs with those obtained directly from the animals being temporarily restrained during capture-release events, to assess the accuracy of our technique. The images will also allow us to compare measurements based on the animals’ sex, age, and reproductive class, as well as between healthy and unhealthy individuals. Our novel health assessment technique could be used to help determine whether capture-release health evaluations of bottlenose dolphins are warranted in areas of concern, and it could be applied in the future to a wide variety of marine mammal species that have yet to be studied in this manner. This system was used to provide body condition data for treatment of a stranded bottlenose dolphin undergoing treatment at Mote’s dolphin hospital.

This article appeared on page 21 in the December 2015 issue of Nicks n Notches.

Measuring bone density in live, free-ranging bottlenose dolphins

James Powell measures bone density in a dolphin flipper.
James Powell measures bone density in a dolphin flipper.

Bone density is an indicator of health in many mammals, including humans. During the 2014 and 2015 Sarasota Bay health assessments, the first-ever measurements of bone density in live, free-ranging bottlenose dolphins were performed. Measurements of bone density in dead, beachcast dolphins are straightforward, as skeletal specimens can be collected and analyzed through traditional laboratory methods; however, novel technology and protocols had to be developed in order to include bone density assessments in the overall health evaluation of live dolphins. To date, bone density profiles have been established for 17 dolphins in Sarasota Bay.

In addition to these measurements, bone density values from archived skeletal specimens for nearly 300 dolphins from both Sarasota Bay and coastal South Carolina were recorded to develop the first ever reference dataset for bottlenose dolphin bone density. This reference dataset is being used as a baseline by which to compare bone density values for dolphins in areas where human impacts, such as high levels of contamination, are of great concern. In September 2015, bone density measurements were incorporated as part of the health diagnostics performed in a NOAA bottlenose dolphin capture-release health assessment in the estuarine and coastal waters near Brunswick, GA, where some of the highest PCB concentrations ever recorded for dolphins have been documented. Bone density values for individual dolphins assessed during this project will be compared to Sarasota Bay resident dolphins and the bottlenose dolphin reference dataset to determine whether coastal bottlenose dolphins differ in bone density from estuarine resident dolphins and to examine whether estuarine bottlenose dolphins exposed to high levels of environmental contamination exhibit lower bone density than dolphins from Sarasota Bay.

This article appeared on pages 19-20 in the December 2015 issue of Nicks n Notches.

 

Dental exams and radiology for dolphins

 dental x-rays on a dolphin
A digital film plate and a handheld radiograph machine enable Jean Herrman to obtain dental x-rays on dolphins while aboard the R/V Flip.

As your dentist will tell you, the mouth is an indicator of overall health. Poor oral health is linked to heart disease and other chronic health conditions in humans and our companion animals. The finding that a portion of a wild dolphin population in Louisiana was missing most of their teeth prompted the desire to investigate the oral health of wild dolphin populations in general.

It is common practice and standard care to not only examine the mouth, but also to take radiographs (x-rays) of the majority portion of the teeth that anchor them into the jawbone and are out of view to the eye. Radiographs may help understand the reasons underlying tooth loss, determining if it was just broken off, or if it is really completely missing. For dolphin mouth x-rays, a digital film plate is inserted within a holder and placed gently into a dolphin’s mouth. A very low dose of x-rays is used with dolphins because the digital plate is very sensitive; the plate is then put through a small digital laser scanner to produce the image.

Dolphins have 76-108 teeth. They are all the same shape and they are born with their adult set of teeth. They are used to grab food only, not for chewing. Typically observed wearing down of teeth in bottlenose dolphins has even led to their name Tursiops truncatus, because their teeth seemed short or truncated compared to other toothed cetaceans. With radiography we have discovered that this typical wear does not affect the supporting bone and even teeth worn down to the gum-line remain vital and healthy. Also it is common for teeth to be broken, sometimes with the gum tissue growing over the roots of the teeth. Most of these roots stay vital and sometimes they remain dead and mildly diseased in the bone. Our radiographic findings also include pocketing around worn teeth especially in the front of the mouth. This is known as periodontal disease and is usually mild, mostly in older dolphins with less than 25% of the supporting bone affected. Occasionally the jawbone loss around teeth throughout the mouth is more severe, affecting a greater number of teeth and loss of greater than 75% of the supporting bone. It is diseased bone or a severe form of periodontal disease that is suspected to be the reason for extensive tooth loss, not normal wear and tear. This has only been confirmed by radiographs in one Sarasota Bay dolphin over the past 3 years, compared to multiple dolphins in other populations.

It will be interesting to be able to link oral disease to other health information being collected by projects on the same dolphins in order to provide a more complete health assessment of our wild dolphin populations. Another potential use for dental radiology will be to provide age information. Dental radiography is used for age determination in human forensics and archeology and I would like to extend this technique to wild dolphins. It would provide a non-invasive tool to age dolphins in health assessments, stranding events, and rehabilitation efforts. The Sarasota Bay population is an important contributor to health and age assessments since most of their life histories and ages are well-known.

This article appeared on page 19 in the December 2015 issue of Nicks n Notches.

Use of mobile x-ray technology for dolphin health assessments

taking radiographs of a dolphin
Mike Walsh taking radiographs of a dolphin aboard the R/V Flip.

The determination of the health status of individual cetaceans as part of an evaluation of population health has dramatically changed over the years. While the sampling of blood has been the foundational approach to assess health it is widely recognized that additional technology such as ultrasound and other imaging techniques can add to the clarity of understanding of the health status of individuals.

In human care of dolphins, or your typical animal hospital, radiographs (x-rays) are also part of a health assessment. Just a few years ago the limits in applying this to animals in a field situation included the need for electricity to run the generator and a method for acquiring images that could be easily taken and stored electronically. The development of digital radiographs to replace the need to develop film in tanks like photographs was a great leap forward and brought us closer to taking the system in the field. With that challenge solved we still needed an electrical source for powering the unit that produces the x-rays and a sensitive plate that receives the exposure and sends the image back to a computer program that can be viewed almost immediately. Both of these needed to be safe and able to handle the presence of water.

X-ray obtained from experimental field radiograph equipment.
X-ray obtained from experimental field radiograph equipment.

Now there are battery operated generators and the next step in realizing the goal was the availability of a wireless plate that communicated directly with the computer eliminating the need for a cord between the plate and the computer. We began working with Vet Rocket, an imaging company founded by Andy Fu, that specializes in radiology equipment where the plate is extremely sensitive, giving great detail, as well as wireless and the generator is powered by a battery pack. We used the system first at Clearwater Marine Aquarium as part of the health assessments for dolphins to show it was quick and applicable. With that success we proposed using the system in the field. Last year was the first try and we imaged the chests of two large males to prove the system could acquire good images even with larger animals. The system worked beyond our hopes and we came back in 2015 to add more information and improve the steps needed to get the images quickly and safely. Our hope is to work in concert with the other technologies such as ultrasound and to help get even more information on chest disease and skeletal changes in this amazing population of animals in Sarasota Bay. We would like to thank the people who are supportive of this project and always making things better for the animals, including Craig Pelton, Andy Fu, Jeff Wood, and Ned Waters.

This article appeared on page 18 in the December 2015 issue of Nicks n Notches.