In the heat of the night: The role of hypoxia on coral reefs
Informations
- Funding country
Norway- Acronym
- -
- URL
- -
- Start date
- 1/1/2021
- End date
- 12/31/2025
- Budget
- 1,886,328 EUR
Fundings
| Name | Role | Start | End | Amount |
|---|---|---|---|---|
| Marine Resources and the Environment (MARINFORSK) - call 2016 | Grant | - | - | 1,886,328 EUR |
Abstract
A tropical coral reef is a colony of tiny animals that secrete a calcified skeleton they live within. They filter the water and feed on small zooplankton, but they also have an alga, called a zooxanthellae, living inside, as a symbiont. This alga receives nutrients from the food the coral has eaten, and in return uses sunlight to make sugars the coral can use. But it is dark during night, and then both the coral and its alga breathe and use the oxygen, and if the water is warm and there is little current then the water can be completely void of oxygen, especially early in the morning. This is critical for the coral, but also for all the fish that shelter for the night within the reef. With life history models, we have seen that this can explain why typical coral reef fishes grow only 2-3 cm per year, whereas cod in the ice cold Barents Sea grows 10 cm per year and Dolphinfish 50 cm in just six months. In this project, we will investigate the consequences of late-night hypoxia for corals and other animals on tropical reefs. We will combine models to formulate hypotheses, physiological laboratory experiments to test some of the expectations, and night-time filming at natural reefs with light-sensitive cameras to record natural behaviours. We will study fish, because they have behaviours that can easily be observed, but also corals. One hypothesis is that coral bleaching, i.e. that the coral expels the zooxanthellae and thereby lose an important source of energy, first and foremost is a response to hypoxia and therefore is initiated during early morning, especially during warm and long nights. We are also expecting that hypoxia becomes more severe as one moves from the outskirts of the reef towards its interior, and that this can gradient can explain why different species of fish and corals are found along the gradient from reef edge to reef interior.