Just in time for Shark Week, we're going down under to investigate what warming waters will do to the distribution of tiger sharks on the east coast of Australia with tiger shark expert, Dr. Yuri Niella!
This week we break down Dr. Yuri Niella et al. (2021) article, "Forecasting intraspecific changes in distribution of a wide-ranging marine predator under climate change."
Article Summary: (modified abstract)
Climate change is causing animal distributions to shift in response to changing temperatures. Typically shifts in these behaviors are evaluated at the species level, but in this study, Nuriella et al. studied behavioral shifts at the individual level. They investigated 115 tiger sharks, Galeocerdo cuvier, from 2002 to 2020, and evaluated how behavior and distribution differed between sex and maturation class (meaning, juveniles or adults). With this long-term data set, Nuriella et al. modeled how behavior and distribution may continue to change in tiger sharks to 2030, and included environmental factoers and predicted occurence of potential prey. Generalised Linear and Additive Models revealed that water temperature change, particularly at higher latitudes, was the factor most associated with shark movements. Females dispersed southwards during periods of warming temperatures, and while juvenile females preferred a narrow thermal range between 22 and 23 °C, adult female and juvenile male presence was correlated with either lower (<22 °C) or higher (>23 °C) temperatures. During La Niña, sharks moved towards higher latitudes and used shallower isobaths. Inclusion of predicted distribution of their putative prey signifcantly improved projections of suitable habitats for all shark classes, compared to simpler models using temperature alone. Tiger shark range of the east coast of Australia is predicted to extend~3.5° south towards the east coast of Tasmania, particularly for juvenile males. This study will assist in evaluating the consequences of climate change to species distribution.
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