1
|
Ruthsatz K, Rico-Millan R, Eterovick PC, Gomez-Mestre I. Exploring water-borne corticosterone collection as a non-invasive tool in amphibian conservation physiology: benefits, limitations and future perspectives. CONSERVATION PHYSIOLOGY 2023; 11:coad070. [PMID: 37663928 PMCID: PMC10472495 DOI: 10.1093/conphys/coad070] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2023] [Revised: 08/03/2023] [Accepted: 08/26/2023] [Indexed: 09/05/2023]
Abstract
Global change exposes wildlife to a variety of environmental stressors and is affecting biodiversity worldwide, with amphibian population declines being at the forefront of the global biodiversity crisis. The use of non-invasive methods to determine the physiological state in response to environmental stressors is therefore an important advance in the field of conservation physiology. The glucocorticoid hormone corticosterone (CORT) is one useful biomarker to assess physiological stress in amphibians, and sampling water-borne (WB) CORT is a novel, non-invasive collection technique. Here, we tested whether WB CORT can serve as a valid proxy of organismal levels of CORT in larvae of the common frog (Rana temporaria). We evaluated the association between tissue and WB CORT levels sampled from the same individuals across ontogenetic stages, ranging from newly hatched larvae to froglets at 10 days after metamorphosis. We also investigated how both tissue and WB CORT change throughout ontogeny. We found that WB CORT is a valid method in pro-metamorphic larvae as values for both methods were highly correlated. In contrast, there was no correlation between tissue and WB CORT in newly hatched, pre-metamorphic larvae, metamorphs or post-metamorphic froglets probably due to ontogenetic changes in respiratory and skin morphology and physiology affecting the transdermal CORT release. Both collection methods consistently revealed a non-linear pattern of ontogenetic change in CORT with a peak at metamorphic climax. Thus, our results indicate that WB CORT sampling is a promising, non-invasive conservation tool for studies on late-stage amphibian larvae. However, we suggest considering that different contexts might affect the reliability of WB CORT and consequently urge future studies to validate this method whenever it is used in new approaches. We conclude proposing some recommendations and perspectives on the use of WB CORT that will aid in broadening its application as a non-invasive tool in amphibian conservation physiology.
Collapse
Affiliation(s)
- Katharina Ruthsatz
- Zoological Institute, Technische Universität Braunschweig, Mendelssohnstraße 4, 38106 Braunschweig, Germany
| | - Rafael Rico-Millan
- Ecology, Evolution, and Development Group, Doñana Biological Station – CSIC, Calle Américo Vespucio 26, 41092 Seville, Spain
| | - Paula Cabral Eterovick
- Zoological Institute, Technische Universität Braunschweig, Mendelssohnstraße 4, 38106 Braunschweig, Germany
| | - Ivan Gomez-Mestre
- Ecology, Evolution, and Development Group, Doñana Biological Station – CSIC, Calle Américo Vespucio 26, 41092 Seville, Spain
| |
Collapse
|
2
|
Santymire RM, Young M, Lenihan E, Murray MJ. Preliminary Investigation into Developing the Use of Swabs for Skin Cortisol Analysis for the Ocean Sunfish (Mola mola). Animals (Basel) 2022; 12:ani12202868. [PMID: 36290254 PMCID: PMC9597772 DOI: 10.3390/ani12202868] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2022] [Revised: 10/09/2022] [Accepted: 10/19/2022] [Indexed: 11/16/2022] Open
Abstract
Simple Summary Zoos and aquaria play an important role in preventing the mass extinction of wildlife through public awareness of conservation issues and providing a safe haven for wildlife populations. Because aquatic populations face many challenges due to pollution and global warming, it is important to develop an understanding of how species can cope with their environment whether it be in the wild or under human care. Here, we were interested in developing non-invasive methods to study fish stress physiology. We use the unique ocean sunfish (Mola mola) to develop the use of skin swabs to measure the stress hormone, cortisol. We used known times of stress including when a mola was injured or ill and during acclimation to the Monterey Bay Aquarium. We found that cortisol increased initially within the first month of being admitted to the aquarium, but returned to normal values afterward. Molas also had elevated cortisol when being treated for an injury or illness. This is the first step in the development of the use of skin swabs to collect samples for stress analysis in the mola. Additional biochemical analysis is needed to confirm these results and allow this method to be applied to other species of fish. Abstract The ocean sunfish (mola; Mola mola) is the heaviest bony fish in the world. This slow-moving fish often is injured by fishing boats that use drift gillnets attributing to its listing as Vulnerable by the IUCN. The Monterey Bay Aquarium (Monterey, CA, USA) has a program that brings in smaller molas from the ocean and acclimates them for an exhibit. When they grow too large for the million-gallon Open Seas exhibit, they are returned to Monterey Bay through a “reverse” acclimatization. Our overall goal was to use skin swabs to evaluate mola stress physiology to better understand the effects of this program. Our objectives were to validate this non-invasive method by taking opportunistic swabs throughout acclimatization and during stressful events. We swabbed each individual (n = 12) in three different body locations. Swabs were analyzed using a cortisol enzyme immunoassay. We averaged the three swabs and examined the absolute change of cortisol from the first taken upon handling to during treatments and the different acclimation stages. We considered elevated cortisol concentrations to be ≥1.5-fold higher than the first sample. Overall, mean (±SEM) cortisol varied among individuals (564.2 ± 191.5 pg/mL swab (range, 18.3–7012.0 pg/mL swab). The majority (four of six) of molas swabbed within the first week or month had elevated skin cortisol compared to their first sample. All seven molas that were being treated for an injury or illness had elevated skin cortisol (range, 1.7- to 127.6-fold higher) compared to their post-acclimation sample. This is the first step in validating the use of non-invasive skin swabs for glucocorticoid analysis in the mola. Further biochemical analysis is needed to determine the specific steroids that are being measured.
Collapse
Affiliation(s)
- Rachel M. Santymire
- Biology Department, Georgia State University, 100 Piedmont Ave SE, 4th Floor, Atlanta, GA 30303, USA
- Correspondence:
| | - Marissa Young
- Veterinary Services, Monterey Bay Aquarium, 886 Cannery Row, Monterey, CA 93940, USA
| | - Erin Lenihan
- Veterinary Services, Monterey Bay Aquarium, 886 Cannery Row, Monterey, CA 93940, USA
| | - Michael J. Murray
- Veterinary Services, Monterey Bay Aquarium, 886 Cannery Row, Monterey, CA 93940, USA
| |
Collapse
|
3
|
Silla AJ, Calatayud NE, Trudeau VL. Amphibian reproductive technologies: approaches and welfare considerations. CONSERVATION PHYSIOLOGY 2021; 9:coab011. [PMID: 33763231 PMCID: PMC7976225 DOI: 10.1093/conphys/coab011] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/08/2020] [Revised: 01/29/2021] [Accepted: 02/07/2021] [Indexed: 06/12/2023]
Abstract
Captive breeding and reintroduction programs have been established for several threatened amphibian species globally, but with varied success. This reflects our relatively poor understanding of the hormonal control of amphibian reproduction and the stimuli required to initiate and complete reproductive events. While the amphibian hypothalamo-pituitary-gonadal (HPG) axis shares fundamental similarities with both teleosts and tetrapods, there are more species differences than previously assumed. As a result, many amphibian captive breeding programs fail to reliably initiate breeding behaviour, achieve high rates of fertilization or generate large numbers of healthy, genetically diverse offspring. Reproductive technologies have the potential to overcome these challenges but should be used in concert with traditional methods that manipulate environmental conditions (including temperature, nutrition and social environment). Species-dependent methods for handling, restraint and hormone administration (including route and frequency) are discussed to ensure optimal welfare of captive breeding stock. We summarize advances in hormone therapies and discuss two case studies that illustrate some of the challenges and successes with amphibian reproductive technologies: the mountain yellow-legged frog (Rana muscosa; USA) and the northern corroboree frog (Pseudophryne pengilleyi; Australia). Further research is required to develop hormone therapies for a greater number of species to boost global conservation efforts.
Collapse
Affiliation(s)
- Aimee J Silla
- Corresponding author: School of Earth, Atmospheric and Life Sciences, University of Wollongong, Northfields Ave, Wollongong, New South Wales 2522, Australia.
| | - Natalie E Calatayud
- Taronga Institute of Science and Learning, Taronga Conservation Society Australia, Taronga, Western Plains Zoo, Obley Rd, Dubbo, New South Wales 2830, Australia
- San Diego Zoo Global-Beckman Center for Conservation Research, San Pasqual Valley Rd, Escondido, CA 92027, USA
| | - Vance L Trudeau
- Department of Biology, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada
| |
Collapse
|
4
|
Santymire RM, Sacerdote-Velat AB, Gygli A, Keinath DA, Poo S, Hinkson KM, McKeag EM. Using dermal glucocorticoids to determine the effects of disease and environment on the critically endangered Wyoming toad. CONSERVATION PHYSIOLOGY 2021; 9:coab093. [PMID: 35186296 PMCID: PMC8849142 DOI: 10.1093/conphys/coab093] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Revised: 05/25/2021] [Accepted: 12/05/2021] [Indexed: 05/15/2023]
Abstract
Amphibian populations are declining worldwide, and increased exposure to environmental stressors, including global climate change and pathogens like Batrachochytrium dendrobatidis (Bd), may be contributing to this decline. Our goal was to use a novel dermal swabbing method to measure glucocorticoid (GC) hormones and investigate the relationship among disease and environmental conditions in the critically endangered Wyoming toad (Anaxyrus baxteri). Our objectives were to (i) validate the use of dermal swabs to measure GCs using an adrenocorticotropic hormone (ACTH) challenge on eight captive toads (4 ACTH: 2 M, 2F and 4 saline as a control: 2 M, 2F), (ii) investigate stress physiology and disease status of toads across six reintroduction sites and (iii) compare dermal cortisol between reintroduced and captive toads. Dermal cortisol peaked immediately after the ACTH and saline injections. Faecal GC metabolites (FGMs) were significantly higher one week after the ACTH injection compared with the week before. Saline-injected toads had no change in FGM over time. Toads were only found in three reintroduction sites and dermal cortisol was similar across sites; however, reintroduced toads had higher dermal cortisol in August compared with June and compared with captive individuals. Bd status did not influence dermal cortisol concentrations. Dermal and faecal hormonal metabolite analyses can be used to study amphibian stress physiology and learn how environmental conditions are impacting population success.
Collapse
Affiliation(s)
- Rachel M Santymire
- Davee Center for Epidemiology and Endocrinology, Lincoln Park Zoo, 2001 North Clark Street, Chicago, IL 60614, USA
- Department of Biology, Georgia State University, 100 Piedmont Avenue SE, Fourth floor, Atlanta, GA 30303, USA
- Corresponding author: Georgia State University, 100 Piedmont Avenue SE, Fourth floor, Atlanta, GA 30303, USA. Tel: +1 404-413-5300.
| | | | - Andrew Gygli
- US Fish & Wildlife Service, Wyoming Ecological Services Field Office, 334 Parsley Boulevard, Cheyenne, WY, 82007, USA
| | - Douglas A Keinath
- US Fish & Wildlife Service, Wyoming Ecological Services Field Office, 334 Parsley Boulevard, Cheyenne, WY, 82007, USA
| | - Sinlan Poo
- Department of Conservation & Research, Memphis Zoo, 2000 Prentiss Place, Memphis, TN 38112, USA
- Department of Biological Sciences, Arkansas State University, P.O. Box 599, State University, Jonesboro, AR 72467, USA
| | - Kristin M Hinkson
- Department of Conservation & Research, Memphis Zoo, 2000 Prentiss Place, Memphis, TN 38112, USA
| | - Elizabeth M McKeag
- USDA Forest Service, Nez Perce-Clearwater National Forests, 104 Airport Drive, Grangeville, ID 83530, USA
| |
Collapse
|