Biology subjects

Howe-Kerr, L. I.

Publications and source records attributed to Howe-Kerr, L. I..

3 recordsLinked to original sources

bioRxiv2021

Thermal stress triggers productive viral infection of a key coral reef symbiont

Climate change-driven ocean warming is increasing the frequency and severity of bleaching events, in which corals appear whitened after losing their dinoflagellate endosymbionts (family Symbiodiniaceae). Viral infections of Symbiodiniaceae may contribute to some bleaching signs, but little empirical evidence exists to support this hypothesis. We present the first temporal analysis of a lineage of Symbiodiniaceae-infecting positive-sense single-stranded RNA viruses ( dinoRNAVs) in coral colonies, which were exposed to a 5-day heat treatment (+2.1{degrees}C). A total of 124 dinoRNAV major capsid protein gene aminotypes (unique amino acid sequences) were detected from five colonies of two closely related Pocillopora-Cladocopium (coral-symbiont) combinations in the experiment; most dinoRNAV aminotypes were shared between the two coral-symbiont combinations (64%) and among multiple colonies (82%). Throughout the experiment, seventeen dinoRNAV aminotypes were found only in heat-treated fragments, and 22 aminotypes were detected at higher relative abundances in heat-treated fragments. DinoRNAVs in fragments of some colonies exhibited higher alpha diversity and dispersion under heat stress. Together, these findings provide the first empirical evidence that exposure to high temperatures triggers some dinoRNAVs to switch from a persistent to a productive infection mode within heat-stressed corals. Over extended time frames, we hypothesize that cumulative dinoRNAV production in the Pocillopora-Cladocopium system could affect colony symbiotic status, for example, by decreasing Symbiodiniaceae densities within corals. This study sets the stage for reef-scale investigations of dinoRNAV dynamics during bleaching events.

ecology↗

bioRxiv2020

Fish predation on corals promotes the dispersal of coral symbionts

Predators drive top-down effects that shape prey communities, but the role of predators in dispersing prey microbiomes is rarely examined. We tested whether coral-eating (corallivorous) fish disperse the single-celled dinoflagellate symbionts (family Symbiodiniaceae) of their prey. Our findings demonstrate that: (1) coral-eating fish egest feces containing live Symbiodiniaceae at densities up to seven orders of magnitude higher than other environmental reservoirs such as sediments and water; (2) Symbiodiniaceae communities in the feces of most corallivores are compositionally similar to those in corals; (3) some obligate corallivore species release over 100 million Symbiodiniaceae cells per 100 m2 per day; and (4) after being egested, corallivore feces often come in direct contact with coral colonies (potential hosts for Symbiodiniaceae). These findings suggest that fish predators can play an important role in symbiont acquisition by corals; such predators may have a previously unrecognized, indirect positive effect on prey health.

ecology↗

bioRxiv2020

On a reef far, far away: Offshore transport of floodwaters following extreme storms impacts sponge health and associated microbial communities

Terrestrial runoff can negatively impact marine ecosystems through stressors including excess nutrients, freshwater, sediments, and contaminants. Severe storms, which are increasing with global climate change, generate massive inputs of runoff over short timescales (hours to days); such runoff impacted offshore reefs in the northwest Gulf of Mexico (NW GoM) following severe storms in 2016 and 2017. Several weeks after coastal flooding from these events, NW GoM reef corals, sponges, and other benthic invertebrates -185 km offshore experienced mortality (2016 only) and/or sub-lethal stress (both years). To assess the impact of storm-derived runoff on reef filter feeders, we characterized the bacterial communities of two sponges, Agelas clathrodes and Xestospongia muta, from offshore reefs during periods of sub-lethal stress and no stress over a three-year period (2016-2018). Sponge-associated bacterial communities were altered during both flood years. Additionally, we found evidence of wastewater contamination (based on 16S rRNA gene libraries and quantitative PCR) in offshore sponges following these flood years, but not during the no-flood year. We show that flood events from severe storms have the capacity to reach offshore reef ecosystems and impact resident benthic organisms. Such impacts are most readily detected if baseline data on organismal physiology and associated microbiome composition are available. This highlights the need for molecular and microbial time series of benthic organisms in near- and offshore reef ecosystems, and the continued mitigation of stormwater runoff and climate change impacts.

microbiology↗