Biology subjects

Williamson, O. M.

Publications and source records attributed to Williamson, O. M..

3 recordsLinked to original sources

bioRxiv2023

Sediment source and dose influence the larval performance of the threatened coral Orbicella faveolata

The effects of turbidity and sedimentation stress on early life stages of corals are poorly understood, particularly in Atlantic species. Dredging operations, beach nourishment, and other coastal construction activities can increase sedimentation and turbidity in nearby coral reef habitats and have the potential to negatively affect coral larval development and metamorphosis, reducing sexual reproduction success. In this study, we investigated the performance of larvae of the threatened Caribbean coral species Orbicella faveolata exposed to sediments collected from a reef site in southeast Florida recently impacted by dredging (Port Miami), and compared it to the performance of larvae exposed to sediments collected from the offshore, natal reef of the parent colonies. In a laboratory experiment, we tested whether low and high doses of each of these sediment types affected the survival, settlement, and respiration of coral larvae compared to a no-sediment control treatment. In addition, we analyzed the sediments used in the experiments with 16S rRNA gene amplicon sequencing to assess differences in the microbial communities present in the Port versus Reef sediments, and their potential impact on coral performance. Overall, O. faveolata larvae exposed to high doses of either sediment type (Port or Reef) exhibited reduced survival and settlement rates, but only the Port sediments resulted in adverse effects in the low-dose treatment. Sediments collected near the Port also contained different microbiomes than Reef sediments, and higher relative abundances of the bacteria Desulfobacterales, which has been associated with coral disease. We hypothesize that differences in microbiomes between the two sediments may be a contributing factor in explaining the observed differences in larval performance. Together, these results suggest that the settlement success and survival of O. faveolata larvae are more readily compromised by encountering port inlet sediments compared to reef sediments, with potentially important consequences for the recruitment success of this species in affected areas.

ecology↗

bioRxiv2021

Effect of species, size, and chimerism on the susceptibility of Caribbean brain coral recruits to stony coral tissue loss disease (SCTLD)

Stony coral tissue loss disease (SCTLD) has devastated coral populations along Floridas Coral Reef and beyond. Although widespread infection and mortality of adult colonies have been documented, no studies have yet investigated the susceptibility of recruits to this disease. Here, we exposed eight-month-old Diploria labyrinthiformis recruits and four-month-old Colpophyllia natans recruits to two sequential doses of SCTLD in the laboratory to track infection and assess potential resilience. Both species began to develop lesions as early as 48 h after exposure began. During the first dose, 59.0% of C. natans recruits lost all tissue (died) within two to eight days of developing lesions, whereas D. labyrinthiformis recruits experienced significantly slower rates of tissue loss and minimal eventual mortality. In C. natans, larger recruits and those fused into groups of multiple genets (chimeras) exhibited the highest survivorship. In contrast, smaller and/or single (ungrouped) recruits had the lowest survivorship (9.9 - 26.5%). After 20 days, a second SCTLD dose was delivered to further test resistance in remaining recruits, and all recruits of both species succumbed within 6 days. Although no recruits showed absolute resistance to SCTLD following repeated exposures, our results provide evidence that interactions between species, size, and chimerism can impact relative resistance. This study represents the first report of SCTLD in Caribbean coral recruits and carries implications for natural species recovery and reef restoration efforts. Additional research on the susceptibility of coral juveniles to SCTLD is urgently needed, to include different species, locations, parents, and algal symbionts, with the goal of assessing relative susceptibility and identifying potential sources of resilience for this critical life history stage.

ecology↗

bioRxiv2020

Neighboring colonies influence uptake of thermotolerant endosymbionts in threatened Caribbean coral recruits

Intervention strategies to enhance coral resilience include manipulating the association between corals and their algal endosymbionts. While hosting thermotolerant Durusdinium trenchii can increase bleaching thresholds in adults, its effects remain largely unknown during the early life stages of Caribbean corals. Here, we tested if Orbicella faveolata recruits could establish symbiosis with D. trenchii supplied by nearby "donor" colonies and examined the resulting ecological trade-offs to evaluate early Symbiodiniaceae manipulation as a scalable tool for reef restoration. We exposed aposymbiotic recruits to 29{degrees}C or 31{degrees}C and to fragments of either Montastraea cavernosa (containing Cladocopium) or Siderastrea siderea (containing D. trenchii). After 60 days, recruits reared with D. trenchii donors hosted nearly three times more D. trenchii than those with Cladocopium donors, suggesting that recruits can acquire Symbiodiniaceae from nearby corals of different species. Temperature did not affect D. trenchii uptake. Next, donor colonies were removed and surviving recruits were maintained for three months at ambient temperatures, after which a subset was exposed to a 60-day heat stress trial. Recruits previously reared at 31{degrees}C survived twice as long at 34{degrees}C as those reared at 29{degrees}C, suggesting that pre-exposure to heat can prime recruits to withstand future thermal stress. In addition, recruits hosting primarily D. trenchii survived twice as long at 34{degrees}C as those hosting little or no D. trenchii. However, the proportion of D. trenchii hosted was negatively correlated with polyp size and symbiont density, indicating a trade-off between growth (of both host and symbiont) and heat tolerance. These findings suggest that, while donor colonies may be effective sources for seeding coral recruits with thermotolerant symbionts, practitioners will need to balance the likely benefits and costs of these approaches when designing restoration strategies.

ecology↗