Project

The heat is on: how might rising temperatures affect shark reproduction?

Species
  • Sharks
Years funded
  • 2021
Status
  • Active
Project types
  • Conservation
  • Research
Description

Carolyn is interested in the potential impact of rising ocean temperatures on the ability of epaulette sharks to successfully reproduce. Her work to date has already investigated how higher temperatures might affect the development of the embryos and hatchlings of these small, egg-laying sharks found across Australia’s Great Barrier Reef. Now, her project is focusing on how thermal stress affects adults and their ability to breed. Using portable ultrasound technology, and based around Heron Island, her research will bring new insights into egg-case development and hormone concentrations in our changing oceans.

The heat is on: how might rising temperatures affect shark reproduction?

Carolyn Wheeler

Project leader
About the project leader

Originally from upstate New York, I found my passion for fish biology during my undergraduate Honours research at the University of New England in Maine. There I was privileged to conduct physiological research on the locally threatened Atlantic sturgeon and a variety of shark and skate species. I am currently a co-tutelle PhD candidate between the School for the Environment at the University of Massachusetts Boston and the ARC Centre of Excellence for Coral Reef Studies at James Cook University. I spent the first half of my PhD working with the...

PROJECT LOCATION : Australia
Project details

The heat is on: how might rising temperatures affect shark reproduction?

Key objective

My research aims to determine the impacts of ocean warming on the seasonality and success of epaulette shark reproduction as a potential indicator for other egg-laying tropical sharks.

Why is this important

With many species of sharks and their relatives threatened worldwide, successful reproduction will be a key component in the recovery of many populations in the future. However, ocean temperatures are slowly rising and we currently do not fully understand how this environmental change may impact reproduction. My research uses a well-studied species, the epaulette shark, to conduct a first assessment of the direct impacts of ocean warming scenarios on reproduction.

Background

Defining life-history characteristics of elasmobranchs over many years of research has provided pivotal data that reveal underlying biology and facilitate effective management and conservation efforts for these species. Among the life-history characteristics, however, reproductive biology and endocrinology have in general been neglected as fields of research for the majority of elasmobranchs. This study aims to use a proposed indicator species and a new combination of methods to predict how climate change will shift reproductive timing and affect success in the future. These reproductive models are crucial for implementing the recovery of elasmobranchs worldwide in our rapidly changing environment.

Aims & objectives

My research has two main objectives. First, I am reassessing the reproductive biology and physiology of epaulette sharks at Heron Island from previous research conducted two decades ago. I hope to determine whether reproduction has changed over the past 20 years and to create a detailed profile of the reproductive cycle in wild sharks. Second, with short-term experiments at the field station, I am determining the maximum temperature tolerance of this species in different life stages (juveniles and reproductively active adults). I expect that, for example, females undergoing egg-encapsulation will have a lower temperature tolerance compared to immature and non-reproducing sharks, as this reproductive process is taxing and is likely to reduce the energy available to cope with increased water temperature. Findings from these objectives will indicate whether reproduction has already shifted in epaulette sharks at Heron Island and will enable us to predict how it may continue to change as a result of ocean warming in the future.