idw – Informationsdienst Wissenschaft
Nachrichten, Termine, Experten
Nachrichten, Termine, Experten
Coral reefs are currently experiencing the largest global bleaching event on record, resulting in mass mortality of reef-building corals worldwide. Additional stressors, such as pollution and overfishing, are further damaging coral health. On many reefs this is causing reef-building corals to be replaced by fast-growing algae, a process called a “phase shift”. Since corals and algae exert different ecosystem effects, these phase-shifts disrupt the functioning of coral reef ecosystems.
Now, new research conducted by an international research team, jointly led by Prof. Dr. Christian Wild (Marine Ecology, University of Bremen), and Dr. Malik Naumann (Coral Reef Ecology, Leibniz Center for Tropical Marine Ecology, ZMT), has discovered that corals and algae differently influence nutrient cycling by the “sponge loop”, a key pathway by which energy and nutrients are transferred up the reef food chain. The results have recently been published in the journal Functional Ecology by the Canadian lead author Dr. Laura Rix, who recently obtained her PhD from University of Bremen. Link to the article: http://onlinelibrary.wiley.com/doi/10.1111/1365-2435.12758/full.
The sponge loop drives nutrient cycling on coral reefs
As the main primary producers on coral reefs, corals and algae release large quantities of energy-rich invisible dissolved organic matter that consists of very small nutrients like sugars and amino acids. Sponges rapidly take up these dissolved nutrients and transform them to larger visible particles that can then be used as a food source by other reef organisms (e.g. worms, crabs or sea stars). This so-called “sponge loop” is believed to play an important role in enabling the energy and nutrients produced by corals and algae to be transferred to higher trophic levels in the reef food web. However, the team of researchers discovered that the dissolved nutrients released by corals and algae are actually processed very differently by coral reef sponges. By carrying out a number of field experiments on a coral reef in the Red Sea, the researchers found that the dissolved nutrients produced by algae were not only taken up more rapidly by sponges, but that they were also transformed into particles at a higher rate. This indicates that algae enhance the recycling of energy and nutrients through the sponge loop.
Phase –shifts and consequences of altered nutrient cycling
Coral reefs rely on efficient but balanced nutrient recycling to maintain their health and high productivity, and there is increasing evidence that altered nutrient cycling may have major consequences for coral reef productivity, food webs and overall ecosystem functioning. The important discovery of this study is that by demonstrating how corals and algae differently influence the sponge loop, these findings shed new light on how phase-shifts from coral to algal dominance may alter nutrient cycling and affect the flow of energy through coral reef food webs. Millions of people worldwide depend on coral reefs to sustain fisheries that provide them with food and income. Global and local stressors, like climate change and overfishing, are responsible for the current catastrophic mass mortality of reef-building corals, and we should be very concerned by how these disturbances are tipping the balance between corals and algae. The findings of this study indicate that not only nutrient cycling but eventually also the important functions and services of coral reef ecosystems will be drastically modified by phase-shifts to algal dominance.
Publication:
Rix et al. (2016) Differential recycling of coral- and algal-derived dissolved organic matter (DOM) by coral reef sponges. Functional Ecology (in press)
Further Information
Prof. Dr. Christian Wild
University of Bremen
Faculty Biology / Chemistry
Marine Ecology
Phone. 0421 218 63367
E-mail: christian.wild@uni-bremen.de Further information:
Leibniz Center for Tropical Marine Ecology (ZMT)
Coral Reef Ecology
Dr. Malik Naumann
Tel. 0421/23800-119
Merkmale dieser Pressemitteilung:
Journalisten, Wissenschaftler
Biologie, Meer / Klima, Umwelt / Ökologie
überregional
Forschungsergebnisse
Englisch
Sie können Suchbegriffe mit und, oder und / oder nicht verknüpfen, z. B. Philo nicht logie.
Verknüpfungen können Sie mit Klammern voneinander trennen, z. B. (Philo nicht logie) oder (Psycho und logie).
Zusammenhängende Worte werden als Wortgruppe gesucht, wenn Sie sie in Anführungsstriche setzen, z. B. „Bundesrepublik Deutschland“.
Die Erweiterte Suche können Sie auch nutzen, ohne Suchbegriffe einzugeben. Sie orientiert sich dann an den Kriterien, die Sie ausgewählt haben (z. B. nach dem Land oder dem Sachgebiet).
Haben Sie in einer Kategorie kein Kriterium ausgewählt, wird die gesamte Kategorie durchsucht (z.B. alle Sachgebiete oder alle Länder).
