In this project, PhD Caterina Coral (NIOZ, 2020 – 2025) studied the ecological functions of biogenic reefs that form rich habitats and complex food ecosystems in the North Sea, focusing on species such as flat oysters, mussels, and tube-building worms, as well as the intricacies of food web structure and function. Caterina’s PhD was part of the larger ReVIFES project; a collaboration between NIOZ (lead), TU Delft, and Wageningen University. Partners in the project were NWO-TTW, Waardenburg Ecology ARK Rewilding, CIV, Ministerie van LVVN, Natuur & Milieu, Roem van Yerseke, Sas Consultancy, Stichting de Noordzee, Van Oord, Waardenburg Ecology, WWF. A comprehensive reference guide is available for North Sea professionals interested in starting their own reef restoration projects: Download the North Sea ReVIFES booklet here.

In this NWO-VENI project, the Phd project of Alumni Fee Smulders, we studied how changes in large herbivore populations and invasive seagrass species impact seagrass ecosystem services in the Caribbean. Our findings highlight the role of green turtles in influencing invasive species dynamics and seagrass recovery. As we know from our previous research, sea turtles can facilitate the expansion of invasive seagrass H. stipulacea by preferring native T. testudinum seagrass. Diverse and abundant herbivore communities can therefore play an important role in limiting the success of invasions. The conservation of these species may serve as a tool to slow down seagrass invasion and mitigate the potential negative effects of invasive plants on the ecosystem community. In addition, we found that large herbivores, such as green turtles, can shape seagrass meadows through top-down effects from humans (tourist feeding) or predators (shark presence). Sea turtle grazing may limit the recovery rates of seagrass, while moderate fish grazing can improve seagrass resilience. For both above- and belowground seagrass recovery rates, gradual warming may increase seagrass resilience to the positive effects of temperature in subtropical parts of its range.

This project by Sara Pino Cobacho, (part of of NESSC) investigated the links between mangroves, seagrass, and coral ecosystems, focusing on biogeochemical processes and especially mangroves. Sara found that mangroves are significantly impacted by global change drivers such as sargassum brown tides, rising temperatures, and local eutrophication. These impacts not only affect their functionality but also create a feedback loop of mangrove degradation. Additionally, mangroves help lower local water pH and exhibit diverse reproductive strategies as adaptive responses to their environment. The mesocosm experiments employed throughout this thesis have played a vital role in addressing key questions regarding mangrove functionality and underlying biogeochemical processes. The knowledge generated in this thesis fills critical gaps in understanding mangrove ecology and can inform management practices to more efficiently restore and conserve mangroves within connected tropical ecosystems. 

Since 2011, thick mats of sargassum have been washing ashore along Caribbean coasts. These beaching events, known as ‘brown tides,’ are causing serious ecological and economic problems. We assessed the biogeochemical pathways of how sargassum brown tides affect mangroves and seagrasses using field observations experiments, lab experiments, and combined it with remote sensing. PhD project Luuk Leemans, Radboud University Nijmegen, with NIOZ and WU, 2019-2024

This project mapped sea turtle foraging and nesting habitats in 6 Caribbean Islands of the Dutch Kingdom of the Netherlands. We studied nesting females and foraging subadults, using satellite tracking on nesting females and foraging subadults, isotope analysis and molecular tools – tracks and summary of the research via this storymap. Project funded by NWO-Caribbean, PhD: Jurjan van der Zee 2014-2019, Postdoc Marjolijn.

We tested and co-developed biodegradable structures to support seagrass restoration, simulating natural feedback mechanisms that enhance establishment and growth. Our experiments in the Wadden Sea and Bonaire led to further refinement of these 3D restoration structures, which are now being used to upscale restoration across multiple ecosystems worldwide by BESE-products and NIOZ.

In this Wadden Sea-wide food web study, we collected stable isotope data from over 10,000 samples to create the first extensive food web of the (Dutch) Wadden Sea, covering 173 species larger than 1 mm from Texel to Eemsdollard. We found that benthic diatoms were the main primary producers, contributing to approximately 70% of the productivity. By examining food web dynamics of foundational species like mussels, we also developed new food web metrics to monitor success in nature conservation.

We investigated the factors driving unique self-organization patterns in seagrass beds.

Using drone aerial imagery, Marjolijn and Jim van Belzen analyzed how turtle grazing and hydrodynamics shape seagrass patterns, offering insights into ecosystem resilience