Use of overhead imaging for body condition assessment

six-rotor remote-controlled helicopter (foreground) at ready
Unmanned aerial vehicle imaging system (foreground), a six-rotor remote-controlled helicopter with a downward-facing digital camera, developed by researchers at the Duke Marine Lab and the Woods Hole Oceanographic Institution to measure dolphin body condition.

The body or nutritional condition of dolphins can significantly affect survival, reproductive success, and susceptibility to disease through impacts on immune function. In addition, it can be a sensitive indicator of prey abundance and individual feeding success, as well as the presence of disease. 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 and 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 cetaceans at sea.

The UAV, which has a digital camera, is designed to be launched from a small boat and to hover precisely over individual animals and collect photographs for detailed measurements of body size and shape (a technique called aerial photogrammetry), which then can be used to derive indices of body condition. Initial field testing of the UAV system was conducted over bottlenose dolphins being temporarily held in large net corrals during capture-release health assessments in Sarasota Bay. These initial trials enabled us to compare measurements (such as total body length and girth) obtained from the aerial photographs with those obtained directly from the animals during capture-release events and, thus, assess the accuracy of our technique.

Our next step will be to use the UAV system to collect measurements of body condition from resident bottlenose dolphins during year-round boat surveys in Sarasota Bay, and to conduct comparisons based on the animals’ sex, age, and reproductive class, as well as comparisons between seasons and between healthy and unhealthy individuals. Our novel health assessment technique could be used in the future to help determine whether capture-release health evaluations of bottlenose dolphins are warranted in areas of concern. In addition, our methodology could be applied to a wide variety of marine mammal species that have yet to be studied in this manner.

This article was published on page 10 in the November 2014 issue of Nicks n Notches

Bottlenose dolphin immunology

University of Connecticut researchers (left to right) Erika Gebhard, Milton Levin, and Lindsay Jasperse process samples for immunology studies.
University of Connecticut researchers (left to right) Erika Gebhard, Milton Levin, and Lindsay Jasperse process samples for immunology studies.

The immune system is very important in an individual’s defense against pathogenic microorganisms that live in one’s environment. Our work with Sarasota Bay dolphins has helped us better understand the normal immune system of bottlenose dolphins and establish reference intervals that can be used to assess the potential effects of man-made or natural stressors, such as the Deepwater Horizon oil spill in the northern Gulf of Mexico.

Using blood samples collected during bottlenose dolphin health assessment, our lab has measured the function of different white blood cell types using functional assays. These assays include the ability of neutrophils and monocytes to engulf foreign particles approximately the size of bacteria (phagocytosis), as well as their ability to produce oxygen free radicals to kill such ingested microorganisms (respiratory burst). We also measure the ability of B and T lymphocytes to proliferate upon stimulation, which mimics the early phase of an immune response. Further, following preliminary results obtained in previous years, we started this year measuring serum cytokines, which are small messenger molecules that direct the magnitude and direction for an appropriate immune response. The results obtained in Sarasota have allowed for the first time the determination of confidence intervals (“normal values”) for some of those functions for which sufficient numbers of animals have been sampled. Those results in a relatively healthy population are currently used to assess the potential health effects of the recent exposure of dolphins to oil following the Deepwater Horizon spill.

This work has been supported by the Chicago Zoological Society, who provided logistical support and access to dolphin samples in Sarasota Bay over many years, as well as continued support from NOAA for similar analyses at different locations in the Gulf of Mexico.

This article was published on page 10 in the November 2014 issue of Nicks n Notches

Welcoming a new vessel to the Sarasota Dolphin Research Program fleet: R/V Challenger

Bottlenose dolphin health assessments are a valuable tool to evaluate individual dolphin health and provide insight into stressors that are impacting the overall ecosystem.  Blood sampling for health evaluation began in 1987 to develop medical histories for the known resident dolphins and provide baseline data for comparison to other free-ranging and managed dolphin populations.

Over the past 26 years since these initial blood data were collected, SDRP researchers, in collaboration with a team of biologists and veterinarians, have developed protocols for clinical evaluation of individual dolphins that minimizes dolphin handling time, optimizes safety and sample collection, and provides a quantitative methodology for assessing the overall health of a dolphin population.  Many of the samples collected for this assessment require immediate processing in the field to ensure that subsequent laboratory analyses are not compromised.

To meet these needs, SDRP researchers began searching for a suitable platform that would serve as a “floating laboratory” to process samples efficiently in the field and provide the highest quality data for laboratory analyses.  The ideal vessel would have a large, stable working platform with good airflow to permit centrifuging of blood tubes, pipetting of serum and plasma, and fine-scale processing of samples while in the field.

After an intensive search, a vessel was located that fit this description, a 24 ft. Sun Tracker pontoon boat, built one year after the first blood samples were collected in Sarasota, in 1988.  The pontoon boat was extremely well cared for and had an open design, which allowed for ample table space to process samples.  A new 90 hp Yamaha 4-stroke was added to the pontoon boat to provide enough power to carry its sampling crew and gear as well as keep up with the rest of the health assessment fleet.

The pontoon boat was named the R/V Challenger in thanks to the Community Foundation of Sarasota County’s Giving Challenge, which raised a large portion of the funding needed to purchase and outfit the vessel, and as a salute to the HMS Challenger expedition of 1872-76 which was a global scientific research cruise that made some of the first discoveries in the field of oceanography.

This article was published on page 48 in the January 2014 Nicks n Notches.

Ultrasound evaluation for pregnancy determination and fetal evaluation in Sarasota Bay dolphins

Ultrasound is a rapid and noninvasive tool for examining the female reproductive tract in bottlenose dolphins.

Techniques have been established to evaluate the ovaries, uterine body, and uterine horns of the female dolphin with ultrasound.

In the case of pregnancy, a fetal assessment is also performed to determine the approximate gestational age and health of the dolphin fetus.  These techniques are extremely valuable and informative, as there is no other way to definitely diagnose a pregnancy and accurately assess the health of a developing fetus.

Ultrasound has been used for decades to evaluate the reproductive status of Sarasota Bay dolphins, and techniques continue to improve over time with increased sonographer experience and advances in ultrasound technology.  During the Sarasota Bay health evaluations, all female dolphins are quickly evaluated to determine if they have the potential to be reproductively mature.  This is generally based on total body length as a rough estimate of age.  If the dolphin is either suspect or confirmed to be old enough to be pregnant, an in-water reproductive ultrasound exam is performed.

Exams are typically performed with the ultrasound technician and ultrasound machine positioned on the stern gate of the research vessel, and the sonographer is partially submerged in the water to allow easy access to the animal.  The sonographer wears heads-up display video goggles, more commonly used by video game players, to view the ultrasound image in bright sunlight.  The research team gently restrains the dolphin while the sonographer quickly gathers sonographic data on the reproductive tract and status.

The ovaries are examined for the presence or absence of ovarian structures, specifically follicles and corpora lutea (CL).  Follicles are typically evidence of active cycling behavior; however large solitary follicles may be cystic.  CLs most commonly represent pregnancy, but can also be consistent with an active cycle in a non-pregnant female or a disease process.  If follicles and/or a CL are detected, images are captured and the structures are measured.

Any evidence of pregnancy, including a CL with or without uterine fluid, warrants close inspection of the uterine horns for an embryonic vesicle or fetus.  If a fetus is detected, the biparietal skull diameter is measured and the fetus staged according to skull size.  An estimated due date can be calculated based on the skull diameter.  The fetus is further evaluated for viability based on a heartbeat, fetal movement, and basic organ definition.  If time allows, motion (M) mode is utilized to measure fetal heart rate, which is another indicator of fetal health.  Color Doppler can also be used to interrogate the umbilical cord vessels, the fetal heart, and great vessels to document presence or absence of blood flow.

Upon return of the research team to land, all images captured during the in-water exam are then reviewed in a dark room to facilitate more thorough evaluation of the sonograms and measurement of significant structures when appropriate.  If needed, additional review is performed by the veterinary sonographer with a marine mammal veterinary radiologist.  During this review, final ultrasound interpretations are made and abnormalities are recorded.

During 2012-13, the SDRP was funded by NOAA’s Marine Mammal Health and Stranding Response Program to compile and examine Sarasota Bay dolphin data collected since 1989 from ultrasound exams for pregnancy determination.  The project involved identifying which cases were observed to result in calves that survived long enough to be observed during regular monthly photographic identification surveys, in order to provide an estimate of the proportion of observed fetuses reaching successful parturition.  Preliminary analyses indicate that about 85% of dolphins with diagnosed pregnancies were subsequently observed with calves.

Understanding female reproductive status, fetal health, and estimated due dates add great value to understanding dolphin population health and behavior.  These data also inform the way animals are handled during their health exam, tracked during the months to follow, and scored with regards to overall health.   We will continue to gather these critical data during future health evaluations, and Sarasota Bay health data will continue to be utilized as the baseline reference values for female reproductive health, pregnancy outcomes, and success in comparisons with other bottlenose dolphin populations, including those potentially impacted by oil spills and other pollutants.


This article was published on page 18 in the January 2014 Nicks n Notches.

Comparing dietary consumption of iron in wild dolphins vs. those in managed collections

Iron storage disease has been reported in a large variety of managed collections of mammal species.

Differences in the amount and bioavailability of iron between natural forages and provisioned diets are most often cited when discussing possible etiologies for iron storage disease among affected species.

Our research goals were to compare the iron levels in the blood of wild and managed dolphins and to analyze fish for iron content from their native and non-native diets. Using this information, our goal was to determine if there is a correlation between diet and iron levels in dolphins.

Dolphin blood values for total iron, AST, ALT, and GGT were compiled from wild and captive populations. The wild population consisted of 180 individuals (93 males, 87 females) ranging from 1 year to 50 years old, provided by the Sarasota Dolphin Research Program. The managed collection data were collected from 12 cooperating marine mammal facilities. The managed population consisted of 118 individuals (58 males, 60 females) with an age range of less than 1 year of age to 59 years old.

Seven species of native fish from Sarasota Bay were used in the study (ladyfish, mullet, pigfish, pinfish, seatrout, spot, and toadfish).  In total, 46 samples of native fish caught during 2009-2012 were analyzed for iron content.  Native fish were caught during fish monitoring surveys conducted by the Sarasota Dolphin Research Program. Six species of non-native fish were used in the study from the managed population diets (herring, capelin, smelt, sardines, mackerel, and saury).  In total, 109 samples of non-native fish from 2009-2012 were analyzed for iron content.

Wild dolphins’ iron levels decreased with age with a slight increase in advanced age. Managed dolphins’ iron levels increased with age. The native diet had an average iron consumption of 22.03 ppm per day and non-native (managed) diets ranged from 16.4 ppm – 17.5 ppm per day. It appeared that managed dolphins consumed less iron than wild dolphins. Wild and managed dolphins’ diet values were based on the average proportions of prey items consumed as reported. Further research is needed to determine the cause for iron overload observed in select dolphins that consume a non-native diet.  Funding for this research was provided by the 2012 International Marine Animal Trainer’s Association (IMATA) research grant.

This article was published on page 17 in the January 2014 Nicks n Notches.