Editorial: Anthropogenic Impacts on the Microbial Ecology and Function of Aquatic Environments

摘要

Since, the beginning of the industrial revolution, anthropogenic pressures on natural environments have steadily escalated due to increased human population size, modification and destruction of habitats, and pollution. This has led to ecosystem degradation and widespread extinction of plant and animal species. In recognition of this unprecedented human impact, a new geological time period, labeled the Anthropocene, has been defined as the time period during which humans have significantly impacted the Earth's geological and ecological systems (Waters et al., 2016 ). During the last 40 years, a growing awareness of the negative impacts of humankind on the Earth has led to enactment of government legislation and a degree of modulation of human behavior. However, the emphasis of these changes in attitude and practice has typically been on the conservation of plants and animals, while the effect of anthropogenic activity on natural microbial populations has been largely ignored. This is a significant oversight because microbial communities are generally the first responders to environmental perturbation and can either augment or buffer environmental shifts via, often complex, positive, and negative feedback loops.Microbes are the most abundant organisms in aquatic ecosystems playing key roles in ecosystem productivity and biogeochemistry. The impacts of anthropogenic activity on the ecology and function of aquatic microbial assemblages are multifarious and often largely undefined, but the advent of powerful new tools including next generation sequencing and novel modeling approaches has begun to shed light on this important question ( Hunt and Ward ; Tan et al. ). The publications presented in this Research Topic are diverse with many, perhaps unsurprisingly, that address the impacts of two of the most important problems facing microbes in aquatic systems, climate change, and pollution.One of the major impacts of climate change on marine and aquatic ecosystems is an increase in sea surface temperature (SST). In their contribution, Tout et al. demonstrated that increasing SST disrupts the Pocillopora damicornis coral microbiome, increasing the occurrence of Vibrio species and in particular the coral pathogen V. corallilyticus. In light of previous evidence that V. corallilyticus can lead to coral bleaching (Ben-Haim and Rosenberg, 2002 ), these patterns provide evidence for an additional mechanism in the mass bleaching events that occur during elevated SSTs. Similar observations of increasing influence of microbial pathogens due to rising SST are being made in other systems. The Petton et al. contribution demonstrated that increasing SSTs are increasing the threat to an important aquaculture species, the Pacific Oyster ( Crassostrea gigas ), which was found to be more susceptible to the ostreid herpes virus (OsHV-1) at an elevated SST. As with the Tout et al. study, disruption of the C. gigas microbiome and replacement with Vibrio species was revealed to be an important factor in the full expression of disease by OsHV-1 ( Petton et al. ).In Europe, warming SST has led to increases in Vibrio infections in both humans and marine animals (summarized in Le Roux et al. ), which catalyzed the first European workshop (Paris, 2015) aimed at forming a research network to improve understanding of the factors driving Vibrio disease events and their impact on human and ecosystem health and, food security ( Le Roux et al. ). Vibrio disease events and pathogen evolution are inextricably linked to how humans interact with their aquatic environment. For example, the dense human population and low-lying geography of the river deltas is hypothesized to have allowed regular intrusion of Vibrio cholerae into human drinking water allowing for adaptation of this deadly pathogen to the human gut ( Boucher et al. ). Based on the conclusions of the workshop, rising SSTs are likely to result in increased and/or more severe disease outbreaks requiring further research to develop strategies for prevention and mitigation. Continuing with the theme of climate change, a potential partial solution to this problem is CO_(2)capture and storage in sub-seabed reservoirs however, Rastelli et al. sounded a warning that CO_(2)leakage from such reservoirs could significantly impact benthic microbial communities affecting carbon cycling and nutrient regeneration processes.In addition to the effects of climate change, anthropogenically-derived water pollution is another major impact within aquatic ecosystems. Contributions to this special issue indicate that influx of pollutants and nutrients into aquatic systems significantly disrupts the structure and function of natural microbial assemblages, leading to reduced species diversity, increased heterotrophy and rises in the numbers of potentially virulent/toxic microbes ( Moreira et al. ; Quero et al. ; Jeffries et al. ). Some of these localized pollution events can also amplify the effects of global-sc