Kasey Dresser | January 10, 2018

Recent research conducted at the University of Adelaide looked at the how commercial fish stocks could be negatively impacted by rising sea temperatures.

To test their theory, PhD student, Hadayet Ullah and supervisors Professor Ivan Nagelkerken and Associate Professor Damien Fordham of the University’s Environment Institute, managed twelve 1,600 liter tanks that mimicked the predicted habitat changes in the ocean. The recreated food webs were maintained for 6 months while the researchers gathered information on survival, growth, biomass, and productivity of the animals and plants to use these measurements in a food web model.

A food web maps out the flow of energy in an ecosystem. At the bottom are algae and other food producers, then intermediate consumers like herbivores and finally predators at the tops. Shifts in the bottom of the energy transfer affects the amount of food available for predators.

“Healthy food webs are important for maintenance of species diversity and provide a source of income and food for millions of people worldwide,” said Mr Ullah. “Therefore, it is important to understand how climate change is altering marine food webs in the near future.”

At the end of the 6 months they found, “climate change increased the productivity of plants, this was mainly due to an expansion of cyanobacteria (small blue-green algae),” said Mr Ullah. “This increased primary productivity does not support food webs, however, because these cyanobacteria are largely unpalatable and they are not consumed by herbivores.” Less food for herbivores would result in a smaller population which means less food for predators.