
Ronald OsingaWageningen University & Research | WUR · Department of Aquaculture and Fisheries
Ronald Osinga
Doctor of Philosophy
About
146
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Introduction
Publications
Publications (146)
Restoration and artificial reefs can assist the recovery of degraded reefs but are limited in scalability and climate resilience. The Mineral Accretion Technique (MAT) subjects metal artificial reefs to a low-voltage electrical current, thereby creating a calcium-carbonate coating. It has been suggested that corals on MAT structures experience enha...
Artificial reefs for coral reef restoration are often concrete-based. After concrete is poured, it initially has a high surface pH (approx. 13), which neutralizes within several weeks. During this curing, colonization by marine microalgae is delayed and also macrobenthos such as corals may be impacted. In this study, we evaluated how concrete curin...
Sea temperature increases may compromise ecological restoration as a tool for recovering degraded coral reefs. A potential solution may lay within using corals with naturally higher thermal resilience, such as intertidal corals. This study aimed at comparing thermal resilience, growth and survival between intertidal and subtidal corals in a recipro...
Caribbean coral reefs account for only 7% of the world total coral reef area but play a vital role in the economy of the Caribbean and the livelihoods of millions of people
who depend upon the reefs for income and employment. Coral cover has declined from 50% in the 1970s to less than 20% today, potentially reducing the ability of
the reefs to prov...
Sea temperature increases may compromise ecological restoration as a tool for recovering degraded coral reefs. A potential solution may lay within using corals with naturally higher thermal resilience, such as intertidal corals. This study aimed at comparing thermal resilience, growth and survival between intertidal and subtidal corals in a recipro...
Global ocean warming and acidification will alter the physicochemical conditions in the deep North-Atlantic Ocean. Here, extensive sponge grounds, often dominated by the demosponge species Geodia barretti, provide three-dimensional structure, habitat and significantly contribute to benthic-pelagic coupling and nutrient cycling processes in the deep...
Restoration is an emerging tool for coral reef conservation, yet despite small‐scale successes there are concerns about high costs and ecological setbacks. Integration between reef ecology and restoration could help address such concerns. A prime example is the use of grazing by herbivores to reduce coral nursery cleaning costs. However, the relati...
Active coral reef restoration is increasingly applied for local reef management, but remains hampered by biological interactions such as coral predation (corallivory). To determine factors that drive corallivory and develop more ecology-based restoration approaches, coral and corallivore communities were characterized and fish bite mark densities q...
Monitoring of reef restoration efforts and artificial reefs (ARs) has typically been limited to coral fragment survival, hampering evaluation of broader objectives such as ecosystem recovery. This study aimed to determine to what extent AR design influences the ecological recovery of restored reefs by monitoring outplanted coral fragments, benthic...
Fish assemblages of different types of artificial reefs can differ greatly in abundance, biomass and composition, with some reef types harboring over five times more herbivores than others. It is assumed that higher herbivorous fish abundance results in a higher grazing intensity, affecting the benthic community by means of enhanced coral recruitme...
The increase of macroalgae at degraded reefs impedes several ecosystem services and calls for effective methods to facilitate a return to coral dominance. Removal of macroalgae (browsing) is typically realized by fish, but the role and identity of browsers at the heavily-fished East African coast is still largely unknown. This study investigated ho...
The massive die-off of the sea urchin Diadema antillarum in 1983–1984 is one the main reasons for low coral recruitment and little coral recovery in the Caribbean. As the natural recovery of D. antillarum is slow to non-existent, multiple restoration studies have been attempted. There are currently three different approaches to obtain individuals f...
The increase of macroalgae at degraded reefs impedes ecosystem services and calls for effective methods to facilitate a return to coral dominance. Removal of macroalgae (i.e. browsing) is typically realized by fish, but the role and identity of browsers at the heavily-fished East African Coast is still largely unknown. This study investigated how b...
To support the use of marine demosponges for collagen production in integrated culture settings, we investigated a low–cost, easily applicable and sustainable production method for the culture of Chondrosia reniformis Nardo, 1847 (Demospongiae, Chondrosiida, Chondrosiidae). Novel methods were tested to culture this collagen-rich demosponge in three...
p>Caribbean coral reefs are in decline and the deployment of artificial reefs, structures on the sea bottom that mimic one or more characteristics of a natural reef, is increasingly often considered to sustain ecosystem services. Independent of their specific purposes, it is essential that artificial reefs do not negatively affect the already stres...
Plumes of re-suspended sediment potentially smother and clog the aquiferous system of filter-feeding sponges with unknown implications for their health. For the first time, we examined the physiological responses of repeated exposure to natural sediment in the glass sponge Vazella pourtalesii, which forms dense sponge grounds in Emerald Basin off N...
Ocean warming has severe impacts on coral reef ecosystems with frequent incidences of coral bleaching. In addition, eutrophication poses an increasing threat to coral reef environments and has been found to increase the vulnerability of corals to thermal bleaching. Eutrophication has accelerated in recent years with coastal nutrient loads expected...
Sponges are ubiquitous components of various deep-sea habitats, including cold water coral reefs, and form deep-sea sponge grounds. Although the deep sea is generally considered to be a food-limited environment, these ecosystems are known to be hotspots of biodiversity and carbon cycling. To assess the role of sponges in the carbon cycling of deep-...
This mini-review evaluates the use of marine sponges in integrated culture systems, two decades after the idea was first proposed. It was predicted that the concept would provide a double benefit: sponges would grow faster under higher organic loadings, and filtration by sponges would improve water quality. It is promising that the growth of some c...
Sponges are ubiquitous components of various deep-sea habitats, including cold water coral reefs and deep-sea sponge grounds. Despite being surrounded by oligotrophic waters, these ecosystems are known to be hotspots of biodiversity and carbon cycling. To assess the role of sponges in the carbon cycling of deep-sea ecosystems, we studied the energy...
To support the successful application of sponges for water purification and collagen production, we evaluated the effect of depth on sponge morphology, growth, physiology, and functioning. Specimens of Eastern Mediterranean populations of the sponge Chondrosia reniformis (Nardo, 1847) (Demospongiae, Chondrosiida, Chondrosiidae) were reciprocally tr...
In this study, we compared the early fish colonization of three types of artificial reefs deployed in the coastal waters of Saba and St Eustatius in the Caribbean: reef balls®, layered cakes and piles of locally obtained basaltic rock. As an indicator of performance, three fish assemblage parameters (abundance, biomass, species richness) were measu...
Coral bleaching due to global warming currently is the largest threat to coral reefs, which may be exacerbated by altered water quality. Elevated levels of the UV filter oxybenzone in coastal waters as a result of sunscreen use have recently been demonstrated. We studied the effect of chronic oxybenzone exposure and elevated water temperature on co...
Effects of depth and turbidity on the in situ pumping activity of the Mediterranean sponge Chondrosia reniformis (Nardo, 1847) were characterized by measuring osculum diameter, oscular outflow velocity, osculum density per sponge and sponge surface area at different locations around the Bodrum peninsula (Turkey). Outflow velocity was measured using...
We studied the effect of chronic oxybenzone exposure and elevated temperature on coral health. Microcolonies of Stylophora pistillata and Acropora tenuis were cultured in 20 flow-through aquaria, of which 10 were exposed to oxybenzone at a field-relevant concentration of ~0.06 μg L ⁻¹ at 26 °C. After two weeks, half of the corals experienced a heat...
Poster presentation on herbivory and corallivory on coral nurseries, at WIOMSA 2019
Coral mariculture involves time-consuming removal of fouling. On natural reefs, this service is provided by grazers. As natural reefs also harbour corallivores, it is debated whether reef-bound fish have a positive or negative effect on coral maricultured near natural reefs. This study quantified the net impact of herbivorous and corallivorous fish...
In this study, novel methods were tested to culture the collagen-rich sponge Chondrosia reniformis Nardo, 1847 (Demospongiae, Chondrosiida, Chondrosiidae) in the proximity of floating fish cages. In a trial series, survival and growth of cultured explants were monitored near a polluted fish farm and a pristine control site. Attachment methods, plat...
Recent research suggests that prior exposure of several months to elevated irradiance induces enhanced thermal tolerance in scleractinian corals. While this tolerance has been reported at the species level, individual coral colonies may react differently due to individual variability in thermal tolerance. As thermal anomalies are predicted to becom...
Figure S1: Image of light spectrum.
Spectrum of Orphek PR-156W.
Table S2: Table displaying significant main effects and interactions (excluding colony).
Summary of significant main effects and interactions based on factorial analysis of variance for photographic analyses and fluorescence (EQY).
Figure S2: Image of each group of ramets after fragging and during heat stress.
Photographs of Stylophora pistillata ramet (one ramet per group) after fragging, and during heat stress (day 44, 51 and 57). Control treatment (CT). Experimental treatment (ET). Colony 1 (C1), Colony 2 (C2) and Colony 3 (C3).
Figure S3: Image of DGGE gel (Symbiodinium ITS2).
DGGE gel displaying Symbiodinium community based on ITS2.
Table S1: Table displaying significant main effects and interactions (including colony).
Summary of significant main effects and interactions based on factorial analysis of variance for specific growth rate (during light treatment), cell density, chlorophyll a and photographic analyses, linear mixed model for fluorescence (EQY) and permutational mu...
In 2010, Dutch dredging and marine contractor, Van Oord, launched a Coral Rehabilitation Initiative as part of its Sustainability and Marine Ingenuity agenda. The key challenge was to demonstrate that already proven small-scale coral breeding techniques can be scaled-up and applied in practice to promote environmental gain around marine infrastruct...
Rates of dark respiration and net photosynthesis were measured on six replicate clonal fragments of the stony coral Galaxea fascicularis (Linnaeus 1767), which were incubated under twelve different combinations of dissolved oxygen (20%, 100% and 150% saturation), dissolved carbon dioxide (9.5 and 19.1 μmol L(-1)) and water flow (1-1.6 cm s(-1) vers...
Zinc levels in artificial seawater are often unnaturally elevated, and thus potentially toxic to aquacultured corals. However, our knowledge of how zinc affects corals is still limited. We tested the effects of zinc supplementation (0, 1, 10 and 100 µg L –1 ) on health, growth, NDVI (a proxy for chlorophyll a ) and overall colouration of the stony...
Zinc levels in artificial seawater are often unnaturally elevated, and thus potentially toxic to aquacultured corals. However, our knowledge of how zinc affects corals is still limited. We tested the effects of zinc supplementation (0, 1, 10 and 100 µg L –1 ) on health, growth, NDVI (a proxy for chlorophyll a ) and overall colouration of the stony...
Coral reef degradation worldwide and the concomitant increasing demand for corals to supply the marine ornamental trade have been driving the growing interest for coral aquaculture. Captive breeding and propagation of corals among aquarium hobbyists and public aquariums is a well-known and established activity. In contrast, the scientific community...
Although many coral reefs have shifted from coral-to-algal dominance, the consequence of such a transition for coral–algal interactions and their underlying mechanisms remain poorly understood. At the microscale, it is unclear how diffusive boundary layers (DBLs) and surface oxygen concentrations at the coral–algal interface vary with algal competi...
Sponges have a remarkable capacity to rapidly regenerate in response to wound infliction. In addition, sponges rapidly renew their filter systems (choanocytes) to maintain a healthy population of cells. This study describes the cell kinetics of choanocytes in the encrusting reef sponge Halisarca caerulea during early regeneration (0–8 h) following...
This study describes in vivo cell turnover (the balance between cell proliferation and cell loss) in eight marine sponge species from tropical coral reef, mangrove and temperate Mediterranean reef ecosystems. Cell proliferation was determined through the incorporation of 5-bromo-2'-deoxyuridine (BrdU) and measuring the percentage of BrdU-positive c...
Coral aquaculture is an activity of growing interest due to the degradation of coral reefs worldwide and concomitant growing demand for corals by three industries: marine ornamental trade, pharmaceutical industry and reef restoration. Although captive breeding and propagation of corals is a well-known activity among aquarium hobbyists and public aq...
The chemical diversity associated with marine natural products (MNP) is unanimously acknowledged as the “blue gold” in the urgent quest for new drugs. Consequently, a significant increase in the discovery of MNP published in the literature has been observed in the past decades, particularly from marine invertebrates. However, it remains unclear whe...
Coral reefs are essential to many nations, and are currently in global decline. Although climate models predict decreases in seawater pH (∼0.3 units) and oxygen saturation (∼5 percentage points), these are exceeded by the current daily pH and oxygen fluctuations on many reefs (pH 7.8-8.7 and 27-241% O2 saturation). We investigated the effect of oxy...
Light spectrum plays a key role in the biology of symbiotic corals, with blue light resulting in higher coral growth, zooxanthellae density, chlorophyll a content and photosynthesis rates as compared to red light. However, it is still unclear whether these physiological processes are blue-enhanced or red-repressed. This study investigated the indiv...
Coral reefs are essential to many nations, and are currently in global decline. Although climate models predict decreases in seawater pH (0.3 units) and oxygen saturation (5 percentage points), these are exceeded by the current daily pH and oxygen fluctuations on many reefs (pH 7.8-8.7 and 27-241% O2 saturation). We investigated the effect of oxyge...
Sponge Pump
“Darwin's Paradox” asks how productive and diverse ecosystems like coral reefs thrive in the marine equivalent of a desert. De Goeij et al. (p. 108 ) now show that coral reef sponges are part of a highly efficient recycling pathway for dissolved organic matter (DOM), converting it, via rapid sponge-cell turnover, into cellular detritus...
Corals are an important source of bioactive metabolites.Coral aquaculture for metabolite production is economically viable. Marine natural products (NP) are unanimously acknowledged as the �blue gold� in the urgent quest for new pharmaceuticals. Although corals are among the marine organisms with the greatest diversity of secondary metabolites, gro...
The process of biofouling of marine structures and substrates, such as platforms or ship hulls, proceeds in multiple steps. Soon after the formation of an initial conditioning film, formed via the adsorption of organic particles to natural or man-made substrates, a population of different bacterial taxa associates under the formation of a biofilm....
Many scleractinian coral species host epizoic acoelomorph flatworms, both in aquaculture and in situ. These symbiotic flatworms may impair coral growth and health through light-shading, mucus removal and disruption of heterotrophic feeding. To quantify the effect of epizoic flatworms on zooplankton feeding, we conducted video analyses of single pol...
Heterotrophy is known to stimulate calcification of scleractinian corals, possibly through enhanced organic matrix synthesis and photosynthesis, and increased supply of metabolic DIC. In contrast to the positive long-term effects of heterotrophy, inhibition of calcification has been observed during feeding, which may be explained by a temporal oxyg...
Several factors may affect heterotrophic feeding of benthic marine invertebrates, including water flow rate and polyp context (i.e., the presence of neighbouring polyps). We tested the interactive effects of water flow rate and polyp context on zooplankton feeding by the scleractinian coral Galaxea fascicularis. Single polyps and colonies were incu...