Sponges and the cycling of food on Caribbean coral reefs

16 November 2017

Last year marine ecologist Jasper de Goeij (UvA-IBED) received a prestigious ERC starting grant for his proposal 'SPONGE ENGINE: Fast and Efficient Sponge Engines Drive and Modulate the Food Web of Reef Ecosystems'. Jasper and his newly formed group are now on their first field trip to the Carmabi Research Station on Curaçao to investigate the role of sponges in the cycling of food on Caribbean coral reefs.

The new team consists of Post-Doc Benjamin Mueller, and PhD candidates Sara Campana, Meggie Hudspith and Niklas Kornder, all part of de department of Freshwater and Marine Ecology.

The role of sponges on coral reefs

Ever since Charles Darwin’s descriptions of tropical coral reefs, researchers are wondering how such hotspots of productivity and biodiversity can thrive while being surrounded by a nutrient-poor ocean. It is becoming increasingly evident that sponges play an important role in the recycling of food, which is crucial for such systems to exist.

On coral reefs, algae and corals release large amounts of energy and nutrients in the water as dissolved organic matter (DOM). However, this potential food source can’t be consumed by most heterotrophic organisms.

Jasper de Goeij and Benjamin Mueller on their way to their study site close to the Carmabi Research Station. Photo: Benjamin Mueller

Recently, Jasper de Goeij was able to show that certain sponges mainly feed on DOM. This abundant food source allows them to constantly replace cells in their bodies and thereby rejuvenate themselves. “Old cells” are then expelled and serve as food source for other organism on the reef.

Through this so-called “Sponge Loop” pathway energy and nutrients stored in DOM is converted into particles and is thereby made available for the reef community.

Sponges recycle food, but how does it work?

While the discovery of the “Sponge Loop” pathway was an important step, it raised many new questions. How do sponges take up DOM? Can all sponges do it or does the growth form and the amount of bacteria living in them matter? Does it make a difference whether the DOM was produced by corals or algae? And how much energy and nutrients are recycled through the “Sponge Loop” pathway?

Niklas Kornder having a closer look at a branching vase sponge Callyspongia vaginalis. Photo: Benjamin Mueller.

To start answering these questions, Jasper de Goeij, PhD students Sara Campana, Meggie Hudspith, and Niklas Kornder, and Post-Doc Benjamin Mueller (UvA-IBED) are currently on a two months field trip at the Carmabi Research Station on Curaçao.

Sara Campana and Meggie Hudspith placing coral branches in ziplock bags to transport them to the Carmabi Research Station to test the processing of coral-derived food for sponges. Photo: Benjamin Mueller

You can follow the research activities of the Sponge Team online:

Author: Benjamin Mueller

Published by  IBED Water