Self-reflection puts fish in hot water

In a narcissistic age, it is not uncommon to think of situations in which spending too long focussed on ourselves can lead to harm.  But what about fish, you might ask?

Today our paper entitled “Social cues can push amphibious fish to their thermal limits” was published in Biology Letters.

This manuscript represents an experimental field study performed in Belize this past spring examining how social information can delay the behavioural thresholds that an amphibious fish exhibits to escape from a thermally stressful environment.  As natural environments are complex systems including abiotic and biotic stressors that may act synergistically, it is important to understand how these interactions operate and impact an animal’s thermal limits.

The mangrove rivulus (Kryptolebias marmoratus), in particular, is an intriguing fish since it routinely leaves the water (emerge) to avoid stressful conditions and in some instances can survive for weeks out of water.  If the water gets too hot or too hypoxic, rivulus will simply jump out and chill out on land.

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K. marmoratus contemplating life on land.  Not quite sure yet.  Photo courtesy Keri Martin, Mount Allison University.

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K. marmoratus out of water – Image courtesy of Keri Martin, Mount Allison University.

In the present study, we demonstrate that the decision to emerge from water onto land is also socially sensitive.

So, what does this have to do with self-image?  Studying social cues from conspecifics can be a challenge if the conspecifics jump out of water first, so we designed an experiment to provide continuous social cues, using a simple mirror placed underwater.

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Supplementary Figure from manuscript

Key Finding: The presence of cues from a conspecific (produced from a mirror) caused the rivulus to delay leaving water until they reach a higher temperature.  This delay is clearly a behavioural decision and not due to enhanced tolerance of warmer temperatures, since their CTmax was not sensitive to the presence of social cuing from the mirror.

This discovery is important since it demonstrates that critical behavioural decisions may affect survival in an animal living in a thermally stressful environment.  Much research into thermal stress to date has focussed on individual responses but social cues are likely just as important to animals in the wild.  We have only addressed what simple visual cues produced by a mirror do to their emersion behaviour.  Extrapolating to how multiple cues will work is, of course, open for future investigation.


 

Full Citation:

Currie, S and Tattersall, GJ. 2018. Social cues can push amphibious fish to their thermal limits.  Biology LettersLink here

 


 

Further Information

K. marmoratus inhabit stress aquatic habitats and can be found often inside crab burrows.

See Dr. Andy Turko’s video from 2012.  It is fascinating to watch:

 

On this year’s trip we took more images attempting to visualise the thermal environments inhabited by the various fish living in the Long Caye.  Here is a thermal image of a crab burrow:

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Thermal image of a crab burrow (central triangular region) capturing a crab leaving the burrow (bottom centre of image).  Rivulus can be found cohabiting with crabs or each other.  Image taken in April 2018 with a FLIR T1030K thermal imaging camera.

Ever hopeful to observe rivulus emerging spontaneously in the field we set up various camera traps and go pros and time lapse images.

The following video depicts a time lapse video (each frame 10 apart) captured with a simple IR webcam of a outdoor, artificial burrow with water, following 3 rivulus over time.  You can see one emerging in the bottom part of the screen and staying out of water.

 

We want to acknowledge Team Rivulus and Fellow Scientists:

Dr. Patricia Wright, University of Guelph

Dr. Suzie Currie, Acadia University

Dr. Andy Turko, University of Guelph

Dr. Tamzin Blewett, University of Alberta

Dr. Emily Standen

Giulia Rossi, University of Guelph

Louise Tunnah, University of Guelph

Keri Martin, Mount Allison University

Dr. D. Scott Taylor (mangrove.org)

Itza Lodge, Long Caye, Belize

Journal Comparative Physiology Ed Board

EdBoard

What was I thinking!?

Seriously, though, I’ve just been invited by Professor Heldmaier to be a member of the Journal of Comparative Physiology B editorial board.  I am honoured!  More especially as one my earliest memories of an influential paper was Heldmaier and Ruf’s 1992 paper on “Body temperature and metabolic rate during natural hypothermia in endotherms” published in J Comp Physiol B.  Their paper really helped to spark my interest in hibernation and thermoregulation as it so elegantly explained concepts that can trip up any novice student of physiology.  Anyhow, it is an honour to be part of Dr. Heldmaier’s team.

So, now, I put out a call to anyone reading this post to consider submitting their comparative physiology research to J Comp Physiol B for consideration.

 

Symposium in Seville – July 2019

Come join us in Seville next year to present on or listen to a great line up of speakers presenting on heat exchange with the environment.

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When the call for abstracts come out, please consider submitting a topic that we might be able to feature in the symposium.

And by the end of our session, you should be able to put this type of image into context!

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Alas, my co-organiser, Dr. Dom McCafferty is 5-6 hours ahead of me and has already posted this!