(Photo: University of Adelaide)
Marine food webs could collapse due to climate change
Thursday, January 11, 2018, 02:50 (GMT + 9)
Research by scientists at the University of Adelaide found that rising sea temperatures, due to global climate change, could contribute to a dramatic collapse of marine "food webs," a situation that harms commercial fish stocks.
The study shows that rising temperatures reduce the vital flow of energy from the primary food producers at the bottom of the food chain (for example, algae), to intermediate consumers (herbivores) and top predators of marine food webs. This can directly affect the availability of food for the main predators, with a great impact on marine species.
The doctoral student and lead author of the study, Hadayet Ullah, emphasizes that having healthy food webs is important to maintain the diversity of marine species, which provide a valuable global source of income and food.
To carry out the study 12 large tanks of 1,600 liters were built, in which the ocean temperature and the acidity of the water caused by the increase of greenhouse gas emissions were imitated. The tanks harbored several marine species, such as algae, shrimp, sponges, snails and fish.
The scientists measured the survival and growth rates, biomass and productivity of all animals and plants by maintaining a mini food web for six months under the expected climate conditions for the future.
Plant productivity increased despite climate change, but was due to an expansion of cyanobacteria (small blue-green algae). However, Ullah explains that this is not compatible with food webs, since the aforementioned bacteria have bad taste and are not consumed by herbivores.
Professor Ivan Nagelkerken, leader of the research project, clarifies that it is necessary to carry out more complex and realistic investigations in order to adequately forecast the impact of climate change on oceanic food webs and fishing productivity.
The study was published in the journal PLOS Biology.