Biology subjects

van der Windt, N.

Publications and source records attributed to van der Windt, N..

3 recordsLinked to original sources

bioRxiv2025

Adaptive strategies of Caribbean sponge holobionts beyond the mesophotic zone

Marine sponges and their microbiomes function together as holobionts, playing essential roles in ecosystem dynamics and exhibiting remarkable adaptability across depth gradients. This study utilized a multi-omics approach, integrating microbiome and metabolome analyses, to investigate adaptive strategies in sponge holobionts inhabiting the mesophotic (80-125 m), upper-rariphotic (125-200 m), and lower-rariphotic (200-305 m) zones of Curacao. We hypothesized that depth-related environmental factors drive distinct adaptive strategies, similar to patterns observed in fish and coral assemblages. Results revealed major differences in holometabolomes and microbial communities between Demospongiae and Hexactinellida sponges, reflecting class-specific adaptive strategies. Notably, phospholipid homeoviscous adaptation to temperature and pressure emerged as a key mechanism in phosphorus metabolism. Adaptations in nitrogen metabolism were linked to diverse ammonia oxidizing archaea (AOA) symbionts, and dissolved organic matter cycling. Hexactinellid microbiomes exhibited intra-specific heterogeneity; however, species-specific associations with AOA symbionts such as Cenarchaeum and Nitrosopumilus were observed. Additionally, the lower-rariphotic hexactinellid holometabolomes highlighted the significance of the nested ecosystem concept through the identification of secondary metabolites produced by their associated fauna (aphrocallistins by zoanthids, and xanthurenic acid by shrimp). This study highlights the ecological significance of sponge holobionts in mesophotic and rariphotic ecosystems, revealing diverse adaptations to unique physicochemical conditions and biotic interactions.

microbiology↗

bioRxiv2023

Humic substances mitigate adverse effects of elevated temperature with potentially critical repercussions for coral reef resilience

Previous observational studies have suggested that terrestrially-derived compounds, most notably humic substances (HS) can protect coral reefs from thermal stress. No study hitherto has, however, tested this hypothesis. In the present study, we used a randomised-controlled microcosm setup to test to what extent HS are able to mitigate the adverse effects of elevated temperature and intense UVB radiation on coral photosynthetic activity, and environmental and host-associated bacterial ercommunities. Our results clearly demonstrate a significant protective effect of HS. Corals in HS-supplemented microcosms had significantly higher photosynthetic activities than those in microcosms subjected to elevated heat and intense UVB radiation. Our results, furthermore, showed that coral reef organisms in HS-supplemented microcosms contained unique bacterial communities enriched with known groups of potentially beneficial bacteria. Our findings have significant repercussions for reef resilience in the face of increasing climate-induced stressors and highlight the importance of restoring coastal forests and the land-sea interface in order to protect coral reefs.

ecology↗

bioRxiv2023

Development and validation of an experimental life support system to study the impact of ultraviolet B radiation and temperature on coral reef microbial communities

In the present study, we developed and validated an experimental life support system (ELSS) designed to investigate the response of coral reef associated bacterial communities to increases in temperature and UVB intensity. The ELSS consisted of 32 independent microcosms, which enables researchers to study the individual and interactive effects of up to three factors using a full factorial experimental design. Temperature can be controlled using water-baths. UV exposure was introduced to the system using UV fluorescent lights. Individual UVB-opaque polyester films were added to the microcosms using a random design. In the validation experiment (stable temperature and no UVB), a coral reef environment was simulated using a layer of coral reef sediment, synthetic seawater, and specimens from five benthic reef species. The species used were two hard corals Montipora digitata and Montipora capricornis, a soft coral Sarcophyton glaucum, a zoanthid Zoanthus sp., and a sponge Chondrilla sp.. To validate the system, we assessed physical and chemical parameters and characterised host and free-living bacterial communities of the ELSS over 34 days and compared these data to those observed in natural reef ecosystems. Water temperature, dissolved oxygen, pH, salinity and dissolved nutrients in the ELSS were similar to those at shallow coral reef sites. Sediment bacterial diversity and composition were more similar to natural-type communities at day 29 and 34 than at day 8 after transfer to the microcosms, indicating a return to natural-type conditions following an initial, apparent perturbation phase. Transplantation significantly altered the bacterial community composition of M. digitata and Chondrilla sp. and increased coral photosynthetic efficiency compared to before transplantation. These results highlight the importance of M. digitata and Chondrilla sp. microbiomes to host adaptation following potential stress events.. Altogether, our results validated the suitability of the ELLS developed in this study as a model system to investigate the responses of coral reef associated bacterial communities to shifts of temperature and UVB radiation and potentially other environmental conditions (e.g., environmental pollution).

microbiology↗