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Visualizing our work

Creating conceptual diagrams that simplify and synthesize complex scientific processes and analyses are crucial to understanding and building upon our work. Take a look at some of the figures coming out of our work below, alongside its figure caption, and a description to position it within the broader content of the research. Click on the title to be taken to the publication.

Global Environmental Change, Dr. Amanda Bates et al.

Climate change is transforming the structure of biological communities through the geographic extension and contraction of species’ ranges. Range edges are naturally dynamic, and shifts in the location of range edges occur at different rates and are driven by different mechanisms. This leads to challenges when seeking to generalize responses among taxa and across systems. The figure below focuses on warming-related range shifts in marine systems to describe extensions and contractions as stages, including a sequence of (1) arrival, (2) population increase, and (3) persistence, or by contrast (1) performance decline, (2) population decrease and (3) local extinction. This stage-based framework can be broadly applied to geographic shifts in any species, life-history stage, or population subset. Ideally the probability of transitioning through progressive range shift stages could be estimated from empirical understanding of the various factors influencing range shift rates. While abundance and occupancy data at the spatial resolution required to quantify range shifts are often unavailable, case studies conducted in this study illustrate how diverse evidence sources can be used to stage range extensions and contractions and assign confidence that an observed range shift stage has been reached. Read more about this study and its suggestions for future directions by clicking on the title above.

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Figure: Stages of geographic range extension and contraction. Grey circles represent suitable habitats spanning a temperature gradient; individuals are indicated by black circles. Range extension and contraction can be considered as a progression from a historical state that, under climate change, is expected to transition through three stages of range change (indicated by black, filled arrows). At preliminary stages, there is a probability of transitioning to a former stage (dotted arrows). Hence the highest confidence that a rangechange  has occurred arises in cases where establishment (extension) or local extinction (contraction) is detected as transitioning through these stages, and is stable.

The otolith-isotope method: An opportunity to examine field metabolic rate as an in situ indicator of climate change within and across juvenile Atlantic cod populations (Gadus morhua)

MSc Thesis, Valesca de Groot
Dr. Amanda Bates, Dr. Clive Trueman, Dr. Bob Gregory


Individual metabolism is a unifying variable in animal ecology, influencing all aspects of performance including growth rate, energetic efficiency, and mortality. As abiotic factors continue to fluctuate due to climate change and anthropogenic disturbance, it is becoming increasingly important to measure an individual's metabolic rate in its natural environment to assess critical energetic tradeoffs.  The otolith-isotope method of recovering field metabolic rate (described above) has recently filled a gap for the bony fishes, linking otolith stable isotope composition to in situ oxygen consumption and experienced temperature estimates, yielding the full temporal history of the energetic costs associated with environmental change in free-ranging fishes. I applied this method to two juvenile Atlantic cod (Gadus morhua) populations (Newman Sound, Canada - cold and Skagerrak Coast, Norway - warm) and found that colder adapted juvenile Atlantic cod are less sensitive to temperature change, and maintain higher metabolic rates, than warmer adapted populations at the cold edge of their range, hinting at population specific thermal adaptation.

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Figure: The stable isotope otolith method is dependent on biochemical processes, in which respiration alters the carbon concentration of two isotopically distinct sources of carbon in the blood (δ13CDIC, δ13Cdiet values), which then undergo fractionation and are deposited into the otolith as an interpretable stable isotope signature (Solomon et al., 2006; Chung et al., 2019a). The stable isotope signatures from DIC and diet are isotopically distinct, and the proportion of carbon derived from metabolic sources (Cresp) can be isolated using a two-component mixing model. Cresp can then be converted to O2 consumption using a species-specific statistical calibration equation (Chung et al., 2019b, Martino 2020), and then converted to field metabolic rate (FMR). The abbreviation RESP stands for respiration (O2 consumption, CO2 production) and the e* in the two-component mixing model stands for the fractionation coefficient. The panels surrounded by solid lines represent processes that occur within the organism, while the dashed lines represent those outside the organism
(Atlantic cod illustration: Cerren Richards).

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