Tag: biopsy

The significance of blubber hormone sampling in conservation and monitoring of marine mammals

By: Alexa Kownacki, Ph.D. Student, OSU Department of Fisheries and Wildlife, Geospatial Ecology of Marine Megafauna Lab

Marine mammals are challenging to study for many reasons, and specifically because they inhabit the areas of the Earth that are uninhabited by people: the oceans. Monitoring marine mammal populations to gather baselines on their health condition and reproductive status is not as simple as trap and release, which is a method often conducted for terrestrial animals. Marine mammals are constantly moving in vast areas below the surface. Moreover, cetaceans, which do not spend time on land, are arguably the most challenging to sample.

One component of my project, based in California, USA, is a health assessment analyzing hormones of the bottlenose dolphins that frequent both the coastal and the offshore waters. Therefore, I am all too familiar with the hurdles of collecting health data from living marine mammals, especially cetaceans. However, the past few decades have seen major advancements in technology both in the laboratory and with equipment, including one tool that continues to be critical in understanding cetacean health: blubber biopsies.

Biopsy dart hitting a bottlenose dolphin below the dorsal fin. Image Source: NMFS

Blubber biopsies are typically obtained via low-powered crossbow with a bumper affixed to the arrow to de-power it once it hits the skin. The arrow tip has a small, pronged metal attachment to collect an eraser-tipped size amount of tissue with surface blubber and skin. I compare this to a skin punch biopsies in humans; it’s small, minimally-invasive, and requires no follow-up care. With a small team of scientists, we use small, rigid-inflatable vessels to survey the known locations of where the bottlenose dolphins tend to gather. Then, we assess the conditions of the seas and of the animals, first making sure we are collecting from animals without potentially lowered immune systems (no large, visible wounds) or calves (less than one years old). Once we have photographed the individual’s dorsal fin to identify the individual, one person assembles the biopsy dart and crossbow apparatus following sterile procedures when attaching the biopsy tips to avoid infection. Another person prepares to photograph the animal to match the biopsy information to the individual dolphin. One scientist aims the crossbow for the body of the dolphin, directly below the dorsal fin, while the another photographs the biopsy dart hitting the animal and watches where it bounces off. Then, the boat maneuvers to the floating biopsy dart to recover the dart and the sample. Finally, the tip with blubber and skin tissue is collected, again using sterile procedures, and the sample is archived for further processing. A similar process, using an air gun instead of a crossbow can be viewed below:

GEMM Lab members using an air gun loaded with a biopsy dart to procure marine mammal blubber from a blue whale in New Zealand. Video Source: GEMM Laboratory.

Part of the biopsy process is holding ourselves to the highest standards in our minimally-invasive technique, which requires constant practice, even on land.

Alexa practicing proper crossbow technique on land under supervision. Image Source: Alexa Kownacki

Blubber is the lipid-rich, vascularized tissue under the epidermis that is used in thermoregulation and fat storage for marine mammals. Blubber is an ideal matrix for storing lipophilic (fat-loving) steroid hormones because of its high fat content. Steroid hormones, such as cortisol, progesterone, and testosterone, are naturally circulating in the blood stream and are released in high concentrations during specific events. Unlike blood, blubber is less dynamic and therefore tells a much longer history of the animal’s nutritional state, environmental exposure, stress level, and life history status. Blubber is the cribs-notes version of a marine mammal’s biography over its previous few months of life. Blood, on the other hand, is the news story from the last 24 hours. Both matrices serve a specific purpose in telling the story, but blubber is much more feasible to obtain from a cetacean and provides a longer time frame in terms of information on the past.

A simplified depiction of marine mammal blubber starting from the top (most exterior surface) being the skin surface down to the muscle (most interior). Image Source: schoolnet.org.za

I use blubber biopsies for assessing cortisol, testosterone, and progesterone in the bottlenose dolphins. Cortisol is a glucocorticoid that is frequently associated with stress, including in humans. Marine mammals utilize the same hypothalamic-pituitary-adrenal (HPA) axis that is responsible for the fight-or-flight response, as well as other metabolic regulations. During prolonged stressful events, cortisol levels will remain elevated, which has long-term repercussions for an animal’s health, such as lowered immune systems and decreased ability to respond to predators. Testosterone and progesterone are sex hormones, which can be used to indicate sex of the individual and determine reproductive status. This reproductive information allows us to assess the population’s composition and structure of males and females, as well as potential growth or decline in population (West et al. 2014).

Alexa using a crossbow from a small boat off of San Diego, CA. Image Source: Alexa Kownacki

The coastal and offshore bottlenose dolphin ecotypes of interest in my research occupy different locations and are therefore exposed to different health threats. This is a primary reason for conducting health assessments, specifically analyzing blubber hormone levels. The offshore ecotype is found many kilometers offshore and is most often encountered around the southern Channel Islands. In contrast, the coastal ecotype is found within 2 kilometers of shore (Lowther-Thieleking et al. 2015) where they are subjected to more human exposure, both directly and indirectly, because of their close proximity to the mainland of the United States. Coastal dolphins have a higher likelihood of fishery-related mortality, the negative effects of urbanization including coastal runoff and habitat degradation, and recreational activities (Hwang et al. 2014). The blubber hormone data from my project will inform which demographics are most at-risk. From this information, I can provide data supporting why specific resources should be allocated differently and therefore help vulnerable populations. Further proving that the small amount of tissue from a blubber biopsy can help secure a better future for population by adjusting and informing conservation strategies.

Literature Cited:

Hwang, Alice, Richard H Defran, Maddalena Bearzi, Daniela. Maldini, Charles A Saylan, Aime ́e R Lang, Kimberly J Dudzik, Oscar R Guzo n-Zatarain, Dennis L Kelly, and David W Weller. 2014. “Coastal Range and Movements of Common Bottlenose Dolphins (Tursiops Truncatus) off California and Baja California, Mexico.” Bulletin of the Southern California Academy of Sciences 113 (1): 1–13. https://doi.org/10.3390/toxins6010211.

Lowther-Thieleking, Janet L., Frederick I. Archer, Aimee R. Lang, and David W. Weller. 2015. “Genetic Differentiation among Coastal and Offshore Common Bottlenose Dolphins, Tursiops Truncatus, in the Eastern North Pacific Ocean.” Marine Mammal Science 31 (1): 1–20. https://doi.org/10.1111/mms.12135.

West, Kristi L., Jan Ramer, Janine L. Brown, Jay Sweeney, Erin M. Hanahoe, Tom Reidarson, Jeffry Proudfoot, and Don R. Bergfelt. 2014. “Thyroid Hormone Concentrations in Relation to Age, Sex, Pregnancy, and Perinatal Loss in Bottlenose Dolphins (Tursiops Truncatus).” General and Comparative Endocrinology 197: 73–81. https://doi.org/10.1016/j.ygcen.2013.11.021.

A day in the office

Join us for a couple boat rides as we study blue whales in the South Taranaki Bight of New Zealand.

In both videos below you can see and hear the field team coordinate to capture photo-identification images of the whale(s) while also obtaining a small tissue biopsy sample. It is important to match the individual whale to the sample so we can link biological data obtained from the sample (genetics, hormones, stable isotopes) to the individual whale. We also carefully take notes on where, when and what we collect in order to help us keep track of our data.

In this video clip you can watch as we gently approach two blues surfacing off the starboard bow of the RV Star Keys in order to capture photo-identification images and a small tissue biopsy sample. Callum Lilley (DOC) on the bow; Leigh Torres, Dawn Barlow, and Todd Chandler (OSU) photographing and coordinating from the flying bridge.

 

We are in the small boat here collecting data on a pair of blue whales. Callum Lilley (DOC) is on the rifle; Leigh Torres (OSU) is on the camera and taking notes; Todd Chandler (OSU) is on the helm.

 

I love it when a plan comes together

By Dr. Leigh Torres

GEMM Lab

After four full-on days at sea covering 873 nautical miles, we are back in port as the winds begin to howl again and I now sip my coffee with a much appreciated still horizon. Our dedicated team worked the available weather windows hard and it paid off with more great absence data and excellent presence data too: blue whales, killer whales, common dolphins, and happily swimming pilot whales not headed to nearby Farewell Spit where a sad, massive stranding has occurred. It has been an exhausting, exhilarating, frustrating, exciting, and fulfilling time. As I reflect on all this work and reward, I can’t help but feel gratified for our persistent and focused planning that made it happen successfully. So, as we clean-up, organize data, process samples, and sit in port for a few days I would like to share some of our highlights over the past four days. I hope you enjoy them as much as we did.

The team in action on the RV Star Keys. Callum Lilley (DOC) on the bow waiting for a biopsy opportunity, Dawn Barlow (OSU) on the radio communicating with the small boat, Kristin Hodge (Cornell) taking photos of whales, Captain James Dalzell (Western Work Boats) on the helm, and Chief Engineer Spock (Western Work Boats) keeping his eyes peeled for a blow. (Photo credit: L. Torres)

 

In the small boat off looking for whales in a lovely flat, calm sea with an oil rig in the background. (Photo credit: D. Barlow)

 

Small boat action with Todd Chandler (OSU) at the helm, Leigh Torres (OSU) on the camera getting photo-id images, and Callum Lilley (DOC) taking the biopsy shot, and the dart is visible flying toward the whale in the black circle. (Photo credit: D. Barlow)

 

The stars of the show: blue whales. A photograph captured from the small boat of one animal fluking up to dive down as another whale surfaces close by. (Photo credit: L. Torres)

 

Collecting oceanographic data: Spock and Jason (Western Work Boats) deploy the CTD from the Star Keys. The CTD is an instrument that measures temperature, salinity, fluorescence and depth continuously as it descends to the bottom and back up again. (Photo credit: L. Torres)

 

The recently manufactured transducer pole in the water off the RV Star Keys (left) deployed with the echosounder to collect prey availability data, including this image (right) of krill swarms near feeding blue whales. (Photo credit: L. Torres)

 

The small boat returns to the Star Keys loaded with data and samples, including a large fecal sample in the net: The pooper scooper Leigh Torres (OSU), the biopsy rifle expert Callum Lilley (DOC), and the boat operator Todd Chandler (OSU). (Photo credit: D. Barlow)

 

Drone operator and videographer, Todd Chandler (OSU) under the towel (crucial piece of gear) to minimize glare on the screen as he locates and records blue whales. (Photo credit: K. Hodge)

 

A still shot captured from the drone footage of two adult blue whales surfacing in close proximity. (Photo credit: T. Chandler)

 

The team in action looking for blue whales in ideal survey conditions with Mt. Taranaki in the background. Todd Chandler (OSU) enters survey data while Dawn Barlow (OSU) spies for whale blows. (Photo credit: L. Torres)

 

A late evening at-sea after a big day sees Callum Lilley (DOC) processing a blue whale biopsy sample for transport, storage and analysis. (Photo credit: K. Hodge)

 

And we can’t forget why so many have put time, money and effort into this project: These blue whales are feeding and living within a space exploited by humans for multiple purposes, so we must ensure minimal impacts to these whales and their sustained health. (Photo credit: D. Barlow)

Biopsy sampling blue whales in New Zealand

By: Callum Lilley

Senior Ranger, Marine – Department of Conservation, Taranaki, New Zealand

During the end of January, I had the privilege to be part of the research team studying blue whales in the South Taranaki Bight, New Zealand.  My role, along with assisting with visual survey, was to obtain biopsy samples from whales using a Paxarm modified veterinary rifle.   This device fires a plastic dart fitted with a sterilized metal tip that takes a small skin and blubber sample for genetic and stable isotope analysis. This process is very carefully managed following procedures to ensure that the whales are not put under any undue stress.  Biopsy sampling provides a gold mine of genetic and dietary information to help us understand the dynamics of this whale population.

Although firing a dart at a creature that is considerably larger than a city bus sounds reasonably easy, it is rarely the case.  The first challenge is to find whales within a large expanse of ocean.  The team then needs to photograph the side of each animal and take note of any distinctive features so that each individual is only sampled once.  Sometimes other work will be undertaken (such as collecting fecal samples, or deploying a drifting hydrophone or unmanned aerial system/drone).  Finally the team will attempt to get close enough to the whales, while taking care not to unduly disturb them, to get a biopsy sample.  Wind, vessel movement, glare, the length of time whales spend underwater and the small target they sometimes present above the water are further challenges.

The video below shows a successful biopsy attempt.  It is a well-coordinated team effort that relies on great communication. You can hear observer Todd Chandler direct the skipper of the vessel Ikatere into position while keeping me (the biopsy sampler) informed as to which whale is surfacing and where.  From the vantage point of the flying bridge, Todd can see the whales’ position and movement (my view is limited from the lower deck).  Todd points out where the whale is surfacing and it momentarily presents a target.  This was the second sample from the two racing whales previously discussed by Dr. Torres, so it will be interesting to see their relationship to one-another.

The ideal angle to approach a whale to take a biopsy sample is from behind at a 45 degree angle, as this causes the least disturbance.  The following video was taken from an unmanned aerial system.  It shows the vessel Ikatere approaching from the whale’s left flank. Department of Conservation (DOC) biodiversity ranger Mike Ogle is on the bow of the vessel and fires a biopsy dart at the whale.  After the biopsy is taken the vessel maneuvers to collect the dart/sample from the water while the whale continues to travel.

In addition to blue whale samples, the DOC permit issued to Oregon State University also allowed for opportunistic sampling of other whales.  The following video was taken during an encounter with a large pod of pilot whales.  The video shows how the lightweight dart bounces off the animal and floats in the water.  Care is taken to communicate its location to the skipper who positions the vessel so it can be retrieved with a net.

Once samples have been retrieved they are handled very carefully to prevent contamination.  The sample is split, with some preserved for genetic analysis and the rest for stable isotope analysis.  Analysis of genetic samples provides information on sex, abundance (through genetic capture-recapture, which is calculated by analyzing the proportion of individuals repeatedly sampled over subsequent seasons), and relationships to other blue whale populations.  Stable isotope analysis provides information on diet.  Also, a portion of all samples will be stored for potential future opportunities such as hormone and fatty acid analysis. It blows me away how much information can be gleaned from these tiny samples!