Search bioRxiv⌕ Search
Home/Archive/bioRxiv

bioRxiv · 10.1101/2022.06.14.495714

Securing algal endosymbiont communities for reef-building corals

Bouwmeester, J.·Daly, J.·Quinn, M.·Henley, E. M.·Lager, C.·Perry, R.·Page, C. A.·Hagedorn, M.
View original source ↗Export metadata ↓

Abstract

Photosynthetic dinoflagellates that live in symbiosis with corals (family Symbiodiniaceae) are fundamental for the survival of coral reef ecosystems. During coral bleaching events, it is assumed that these symbionts remain available in the water column, in sediments, or are seeded from unbleached coral colonies. Yet, this hypothesis has not been verified and it remains unclear whether some diversity of Symbiodiniaceae may be lost in the process. Culture methods have been developed for some Symbiodiniaceae, but for the vast majority of these photosynthetic symbionts, known culture methods are not successful at maintaining them for extensive periods. For these unculturable symbionts, cryopreservation, which places cells and tissues in suspended animation for days to decades, offers the best hope for saving the biodiversity of these crucial coral partners. Some cryopreservation processes use slow freezing, but if the cells are sensitive to low temperatures, as is the case for Symbiodiniaceae, then rapid freezing, called vitrification, is needed. We here, tested two published vitrification protocols that had been designed for algal symbionts extracted from Hawaiian corals, but we were unable to recover living symbionts after vitrification and warming. Therefore, we report a successful optimisation of the former vitrification protocols, which we tested on algal symbionts freshly extracted from three Hawaiian coral species, the development of ultra-rapid laser-warming cryopreservation techniques for symbionts, and banking procedures for algal symbionts. We also present some successful uptake of cryopreserved algal symbionts by coral larvae, although at a low rate. It is unclear why the former vitrification protocols failed but we propose that it may have been related to thermal stress and bleaching events that occurred on several occasions throughout the Hawaiian Islands. Maintenance of biodiversity is essential for sustaining functional, productive ecosystems with the adaptability to effectively recover from disturbances. By successfully cryopreserving and banking coral symbionts, we provide a critically needed component for securing Symbiodiniaceae biodiversity into the future.

Explore related subjects

zoologyPreprint

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Bouwmeester, J., Daly, J., Quinn, M., Henley, E. M., Lager, C., Perry, R., Page, C. A., Hagedorn, M.. 2022-06-15. Securing algal endosymbiont communities for reef-building corals. https://doi.org/10.1101/2022.06.14.495714

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related preprints

bioRxiv2026

Impact of iron-enriched diets on the nutritional composition and microbiome diversity of house crickets (Acheta domesticus)

Iron deficiency (ID) and iron-deficiency anaemia (IDA) pose significant global health challenges. ID and IDA are particularly widespread in Sub-Saharan Africa and South Asian countries, where reliance on plant-based foods is high. Edible insects provide an alternative nutritious food source, rich in both protein and essential minerals and trace elements. Little is known about how dietary iron manipulation affects the trace element bioaccumulation and microbiome community composition of edible insects. This study examined the impact of dietary iron supplementation on the growth, survival, nutrient profile, and microbiome of Acheta domesticus. Experimental diets were formulated using iron (II) sulphate heptahydrate, resulting in final iron concentrations ranging from 333.45 mg Fe/kg (control diet) to 6923.39 mg Fe/kg (100 mM Fe diet). Iron supplementation significantly altered the cricket trace element profile, with iron levels increasing fivefold from basal 21.38 mg/kg to 118.34 mg/kg in the highest iron treatment group. Concurrently, manganese levels showed a strong negative correlation with dietary iron, while zinc and cadmium displayed non-significant downward trends. High-iron diets statistically altered dry matter, chitin, and TBARS, whereas carbohydrates, protein, glycogen, and lipids remained stable. Amino acid profiles shifted progressively, with branched-chain, sulphur-containing, and aromatic amino acids peaking in the 25 mM Fe group. In contrast, the diversity and overall structure of the microbial community remained unaffected across all treatments. In conclusion, tailoring dietary iron can significantly boost the iron content of Acheta domesticus without compromising host survival or altering core microbial structures. To optimize insect rearing strategies aimed at alleviating human micronutrient deficiencies, a feeding dose of 10-25 mmol Fe/kg is recommended.

zoology↗
bioRxiv2026

Tardigrades survive reversible dormancy during spaceflight: In-orbit revival, post-flight recovery, and transcriptomic responses

Long-duration space missions face substantial challenges, including limited resources and prolonged exposure to microgravity and radiation. Transporting organisms in a dormant state and reviving them at their destination could help overcome some of these limitations. However, the feasibility of this strategy has not been experimentally demonstrated in multicellular animals beyond Earth. Here, we investigated this possibility using tardigrades, microscopic invertebrates capable of entering a reversible state of dormancy. We demonstrate that dormant tardigrades can withstand near-absolute-zero temperatures (~12 mK), near-vacuum conditions (10-9 mbar), high doses of ionizing radiation (3000 Gy), and complete desiccation. We transported dormant tardigrades to the International Space Station (ISS). They were revived aboard the ISS, subsequently returned to a dormant state, and successfully revived again following their return to Earth. Approximately 45% of the space-flown tardigrades survived the 64-day experimental period. This included two dormancy-revival cycles, 18 days aboard the ISS, and prolonged periods without food or water. Importantly, surviving tardigrades retained their reproductive capacity. Transcriptomic analysis of ISS-exposed tardigrades revealed upregulation of genes associated with protein folding and stress responses, accompanied by downregulation of genes involved in energy metabolism and protein synthesis, providing insights into their molecular responses to the spaceflight environment. Together, these findings demonstrate the successful revival and re-induction of dormancy in a multicellular animal beyond Earth and establish an experimental foundation for exploring dormancy-based strategies for future long-duration space missions.

zoology↗
bioRxiv2026

A baseline for aquatic parasite diversity in West African mangroves: host-parasite records, DNA barcodes, and an experimental design for future use

Macroparasites represent a major fraction of biodiversity and biomass in marine ecosystems, yet remain substantially underrepresented in ecological surveys and food-web models, particularly in the Global South. This study addresses this geographic bias by providing the first comprehensive ecological survey of macroparasite communities of fishes in a West African Marine Protected Area (MPA) and adjacent Open-Access Area (OAA) characterised by mangrove forests. We collected 5,020 parasite specimens from 10 fish and one crab species in the Saloum Delta, Senegal, identifying 27 parasite species across all major taxa. Our findings include 15 new records for Senegal of which 11 are also new for West Africa. Additionally, 64% of host-parasite combinations constitute new host records. We provide 208 DNA barcodes, offering the first molecular data for 31% of these species globally and establishing a reference library for future DNA metabarcoding efforts in the region. Using sample size-corrected biodiversity indices and mixed-model analyses, we detected significant variations in parasite infracommunities and component communities between the MPA and OAA, demonstrating the feasibility of using comparative study designs to monitor fisheries impacts on parasite diversity in the Saloum Delta. Furthermore, the identification of trophically transmitted parasites provided evidence of unstudied food-web connections, e.g. predator-prey linkages between fishes and higher-trophic-level definitive hosts including birds and elasmobranchs. By integrating morphological identification, molecular data, and archiving of voucher specimens into publicly accessible, curated collections, this study establishes a new baseline for marine parasite biodiversity in West Africa and provides a methodological blueprint for surveying understudied regions.

zoology↗