Coral reefs occupy <1% of the seafloor yet harbour a quarter of marine biodiversity in the world. They contribute the protein upon which hundreds of nations depend, underpin enormous sources of economic income and employment, and shelter 150,000 km of tropical coastlines from erosion.

Planetary‐scale climate change and a wealth of anthropogenic pressures have altered coral reefs worldwide, and are projected to worsen. Our research group focuses on understanding how reefs function in the Anthropocene viewing humans as major engineers of environmental change, threat mitigation, preservation, and restoration. Our work spans four research themes:

Reefs in our changing climate

Reefs and our changing climate

Projects framed in this theme aim to understand how reefs recover or reorganise following acute climate-driven perturbations (e.g. bleaching events), and how their functional diversity varies across latitude and changes in response to rising sea surface temperatures (CLIFTEP). We also aim at quantifying current levels of ecosystem functions underpinned by mobile reef fauna (e.g. fish) and predict how these will change under future realistic climate change scenarios (REEF FUTURES).



Reefs and ocean pollution

reef systems 3Ayu Christien Rahaweman setting up her pollution experiments by Achim Meyer

Here we focus on documenting corals’ responses to a range of pervasive ocean pollutants including microplastics, herbicides, and sunscreen filters. We ask whether a) corals react differently to microplastics of different shapes, b) microplastics disrupt key ecological functions of corals, and c) polyps undergo high levels of stress when inspecting or ingesting microplastics.
Most work in this theme is carried out at our Marine Experimental Facility (MAREE) and will develop in further novel directions in collaboration with the Microsensor Group in the Max Planck Institute for Marine Microbiology.

reef systems 3Small colony of Pocillopora damicornis exposed to irregular PET microplastics in the MAREE. In the field, we have also aimed at understanding how coral reefs living in atypically turbid and polluted conditions function. In this context, we joined the research efforts of Pontificia Universidad Javeriana de Cali and Fundacion Ecomares in Varadero reef which may paradoxically be one of the best coral reefs n the continental shelf of Colombia despite being exposed to heavy industrial and sewage waste.




Protecting reefs functioning with traditional conservation measures

reef systems 4High diversity reef in Raja Ampat, Indonesia by Sonia Bejarano

Projects in this theme investigate the role of marine protected areas (MPAs) and fishing gear regulations in sustaining functionally diverse fish communities over time. We also ask whether reefs within protected and fished areas exhibit divergent post-disturbance trajectories. This has been possible by establishing long-term field experiments but also analysing long term coral reef monitoring datasets.

Linking functional traits, functions, biodiversity and reef resilience

reef systems 5 S. Bejarano measuring fish morphology during catch surveys in Pohnpei by Kevin Rhodes

This theme is a fundamental pillar to all other themes. We concentrate here in measuring and compiling different functional traits for different species and individuals, understanding their relationship to function levels, and how they make species more or less vulnerable to perturbation. So far we have focused on fish traits (morphological and behavioural), asking how morphology relates to swimming performance and proving that strong wave energy prevents certain species from feeding affecting the make-up of herbivory.

Research Projects

Research Projects (completed)


A glimpse into some of our starting and ongoing projects

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The future of reef services in the Anthropocene (REEF FUTURES)

The Reef Systems Work group is the German partner of this project funded by BiodivERsA Belmont Forum through the DFG. This project is a collaboration among 18 partners from 11 countries co-directed by Professors David Mouillot and Loïc Pellisier. REEF FUTURES tackles the accelerated loss of biodiversity and deterioration of ecosystem services which are distinctive marks of the Anthropocene. Our general goal is to quantify five key ecosystem services provided by reef fishes to the World’s coasts. At the Reef Systems workgroup we will focus on fishes’ inputs to the carbon cycle through the egestion of carbonates that accompanies osmoregulation. This information will be integrated in models aimed to predict future ecosystem service levels under multiple scenarios of human demography, economic development, and climate change. In the context of REEF FUTURES the Reef Systems group will welcome its first PhD student in August 2019.

Coral polyp interactions with microplastics and natural particles (CORALASTIC)

While plastic debris is ubiquitous in the ocean, our understanding of the interactions between corals and microplastics remains incipient. CORALASTIC is the first to document how coral polyps respond to microplastics. For two branching corals species in laboratory experiments, we a) characterised the typical behaviours polyps display when exposed to realistic concentrations of fibres and irregular polyethylene terephthalate MP, b) determined whether these responses changed with MP shape, and c) whether MP interfere with the corals’ feeding and sediment-shedding functions. Two publications summarising our findings are currently in preparation.

Climatic drivers of reef fish functional diversity in the Tropical Eastern Pacific (CLIFTEP)

This ZMT funded project will start in August 2019 with the engagement of the first post-doctoral researcher of the Reef Systems workgroup. The aim of this project will be to analyse historical databases of reef fish abundance compiled throughout the Eastern Tropical Pacific in order to (i) compile species traits related to various functions, (ii) quantify how fish abundance and trait diversity vary across latitude, (iii) determine which historical, geographic, oceanographic, and climatic factors explain the current spatial patterns of abundance and functional diversity, and (iv) examine how has functional diversity changed in selected locations over the past decade. This project will be conducted in collaboration with the Systems Ecology at ZMT and the University of São Pablo.

Mangrove trees on back reefs: Familiar functions in unlikely places (ReefTREES)

While mangroves usually grow and develop on soft-bottom sediments, some trees were able to settle on consolidated sediment on a backreef system in Laucala Bay, south of Suva in Fiji. The atypical occurrence of mangrove trees on a backreef located relatively distant from the shore, provided us with the perfect natural setting to study the changes in physical and chemical attributes and processes that follow mangrove establishment, together with their effect on the associated fauna. This project is a collaboration between the Reef Systems and the Mangrove Ecology workgroups. Two Master’s theses and respective publications are currently in preparation.

Post-bleaching trajectory of branching corals inside and outside Fijian tabu areas

This project is the result of an ongoing collaboration between the Reef Systems Workgroup and Reef Explorer Fiji (Victor Bonito). Here, we have tracked a 1-year field experiment to investigate the changes undergone by branching coral colonies since their mortality followed the massive bleaching event in February 2016. The progressive colonisation of the coral skeletons by algae, as well as the changes in fish assemblages associated with the colonies have been documented using photo and video cameras, respectively. The analysis of videos and photos is nearly concluded and a publication will be finalised this year.

To feed or not to feed? The effects of artificial feeding on coral reef fish functions in the Aitutaki lagoon, Cook Islands

Feeding wild animals is a regular habit in ecotourism worldwide, with poorly-known consequences for ecosystem function. This project was led by Natalie Prinz to complete her Master’s degree in International Studies in Aquatic Tropical Ecology, and co-supervised by Dr. Sebastian Ferse. It aimed to determine the effects of a regular tourism practice (i.e. bread feeding) on the abundance and diversity of fish assemblages in the reef lagoon of Aitutaki (Cook Islands). Species with the highest and lowest affinity for artificial food were identified. Focusing on a corallivore (Chaetodon auriga) and a grazer-detritivore (Ctenochaetus striatus), changes in natural feeding behaviours resulting from artificial feeding with important implications for fish functions were documented. Miss Prinz’s thesis received the prestigious Campus Award in 2018, and her publication is currently in review.