• Going with the flow: How corals in high‐flow environments can beat the heat

      Fifer, James; Bentlage, Bastian; Lemer, Sarah; Fujimura, Atsushi G.; Sweet, Michael; Raymundo, Laurie J.; University of Guam Marine Laboratory, UOG Station, Mangilao, GU, USA; Boston University, Boston, MA, USA; University of Derby (Wiley, 2021-03-02)
      Coral reefs are experiencing unprecedented declines in health on a global scale leading to severe reductions in coral cover. One major cause of this decline is increasing sea surface temperature. However, conspecific colonies separated by even small spatial distances appear to show varying responses to this global stressor. One factor contributing to differential responses to heat stress is variability in the coral's micro‐environment, such as the amount of water flow a coral experiences. High flow provides corals with a variety of health benefits, including heat stress mitigation. Here, we investigate how water flow affects coral gene expression and provides resilience to increasing temperatures. We examined host and photosymbiont gene expression of Acropora cf. pulchra colonies in discrete in situ flow environments during a natural bleaching event. In addition, we conducted controlled ex situ tank experiments where we exposed A. cf. pulchra to different flow regimes and acute heat stress. Notably, we observed distinct flow‐driven transcriptomic signatures related to energy expenditure, growth, heterotrophy and a healthy coral host–photosymbiont relationship. We also observed disparate transcriptomic responses during bleaching recovery between the high‐ and low‐flow sites. Additionally, corals exposed to high flow showed “frontloading” of specific heat‐stress‐related genes such as heat shock proteins, antioxidant enzymes, genes involved in apoptosis regulation, innate immunity and cell adhesion. We posit that frontloading is a result of increased oxidative metabolism generated by the increased water movement. Gene frontloading may at least partially explain the observation that colonies in high‐flow environments show higher survival and/or faster recovery in response to bleaching events.
    • Improving the reliability of eDNA data interpretation

      Burian, Alfred; Mauvisseau, Quentin; Bulling, Mark; Domisch, Sami; Qian, Song; Sweet, Michael; University of Derby; Marine Ecology Department, Lurio University, Nampula, Mozambique; Helmholtz Centre for Environmental Research, Leipzig, Germany; Natural History Museum, University of Oslo, Oslo, Norway; et al. (Wiley, 2021-03-25)
      Global declines in biodiversity highlight the need to effectively monitor the density and distribution of threatened species. In recent years, molecular survey methods detecting DNA released by target‐species into their environment (eDNA) have been rapidly on the rise. Despite providing new, cost‐effective tools for conservation, eDNA‐based methods are prone to errors. Best field and laboratory practices can mitigate some, but the risks of errors cannot be eliminated and need to be accounted for. Here, we synthesize recent advances in data processing tools that increase the reliability of interpretations drawn from eDNA data. We review advances in occupancy models to consider spatial data‐structures and simultaneously assess rates of false positive and negative results. Further, we introduce process‐based models and the integration of metabarcoding data as complementing approaches to increase the reliability of target‐species assessments. These tools will be most effective when capitalizing on multi‐source data sets collating eDNA with classical survey and citizen‐science approaches, paving the way for more robust decision‐making processes in conservation planning.