[MARMAM] New study on manatee thermoregulation

Nicola Erdsack erdsack at mote.org
Sun Nov 5 16:51:33 PST 2023


Dear colleagues,

my co-authors and I are pleased to announce our new publication on 
manatee thermoregulation:

*Erdsack, N., Galves, J. A., & Powell, J. A. (2023). Heat loss or heat 
uptake? Skin temperature in Antillean manatees (**/Trichechus manatus 
manatus/**, Sirenia: Trichechidae) in Belize. International Journal of 
Tropical Biology and Conservation / Revista de Biología Tropical, 
71(54), e57272. doi: 10.15517/rev.biol.trop..v71iS4.57272*

Abstract:

Introduction: The two subspecies of the West Indian manatee (/Trichechus 
manatus/), Florida manatees (/T. m. latirostris/) and Antillean manatees 
(/T. m. manatus/), face different environmental challenges. While 
Florida manatees have to cope with winter water temperatures below their 
lower critical temperature of ~20°C and air temperatures below freezing, 
Antillean manatees live in year-round warm Caribbean waters. Sirenians 
lack effective thermal insulation and have limited capability of 
controlling peripheral heat loss. Although severe cold related health 
issues and mortality are primarily known in Florida manatees, it can be 
assumed that Antillean manatees and other extant sirenians  share the  
cold-sensitivity, but hardly ever experience it. Contrarily, during 
summer, Antillean manatees may face the opposite form of thermal stress 
by being exposed to water temperatures close to their body temperature. 
However, the upper critical temperature of manatees is not known. 
Objective: To improve understanding of the impact of high ambient 
temperatures on manatee physiology. Methods: We measured skin 
temperature in six Antillean manatees in two different habitats in 
Belize, and compared the results to skin temperatures measured in two 
captive Florida manatees. Results: We found a similar temperature 
distribution pattern over the body surface in both subspecies, but 
significantly higher temperatures and larger temperature ranges among 
measuring points in Antillean manatees as compared to Florida manatees. 
In one Antillean manatee, skin temperature was consistently lower than 
ambient water temperature by up to 2.5°C. This implies potential heat 
uptake from the environment, in contrast to the heat loss experienced by 
Florida manatees at low water temperatures, apparent in skin 
temperatures above ambient water temperature. Conclusions: Our findings 
suggest that heat stress may be a more likely risk for manatees in warm 
tropical waters. Despite the small sample size, our results present 
important findings towards understanding thermal tolerance and impact of 
high ambient temperatures on manatee physiology.

The study is published as part of a Special Issue on Aquatic Mammals of 
Central America and accessible at:

https://revistas.ucr.ac.cr/index.php/rbt/article/view/57272/57784

Best regards,

Nicola, Jamal & Buddy

-- 
************************************
Nicola Erdsack, Ph.D.
Affiliate Scientist Manatee Research
Mote Marine Laboratory & Aquarium
1600 Ken Thompson Pkwy
Sarasota, FL 34236
cell  +1-941-284-0708
erdsack at mote.org
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