Direct and Indirect Influence of Parental Bedrock on Streambed Microbial Community Structure in Forested Streams

Abstract

A correlative study was performed to determine if variation in streambed microbial community structure in low-order forested streams can be directly or indirectly linked to the chemical nature of the parental bedrock of the environments through which the streams flow. Total microbial and photosynthetic biomass (phospholipid phosphate [PLP] and chlorophyll a), community structure (phospholipid fatty acid analysis), and physical and chemical parameters were measured in six streams, three located in sandstone and three in limestone regions of the Bankhead National Forest in northern Alabama. Although stream water flowing through the two different bedrock types differed significantly in chemical composition, there were no significant differences in total microbial and photosynthetic biomass in the sediments. In contrast, sedimentary microbial community structure differed between the bedrock types and was significantly correlated with stream water ion concentrations. A pattern of seasonal variation in microbial community structure was also observed. Further statistical analysis indicated dissolved organic matter (DOM) quality, which was previously shown to be influenced by geological variation, correlated with variation in bacterial community structure. These results indicate that the geology of underlying bedrock influences benthic microbial communities directly via changes in water chemistry and also indirectly via stream water DOM quality.Microorganisms are one of the most important groups of living organisms. Their small size, ubiquitous distribution, metabolic diversity, and genetic plasticity cast microorganisms in the role of recycling agents for the biosphere, making life possible for more complex organisms (47). To better understand the ecology of microbial communities, it is important not only to describe the community composition but also to identify biological and/or environmental factors that regulate their diversity (34, 52).Baas-Becking's dictum that "everything is everywhere, but the environment selects" has inspired many studies and debates since its inception and is considered the precursor to the niche concept adopted by macroecologists (10). Microbes were thought to be cosmopolitan due to large population sizes and short generation times, resulting in high dispersal rates (18,22). Many studies in the past were limited by methodological tools to elucidate bacterial species, as most bacteria found in the natural environment have yet to be cultured and functional roles and diversity were largely unknown (56, 64). With the recent advances in non-culture-dependent techniques, there has been an increase of studies that have shown evidence of varying distributions, abundance, and diversity of microorganisms in the natural environment across spatial and environmental scales, including freshwater lakes and rivers (60, 65, 70), streams (28), soils (8,21,51,57), and marine ecosystems (33,54). Yet, it is not clear whether limits in distribution or strong environmental selection lead to the observed patterns....

Both species sorting and neutral processes drive assembly of bacterial communities in aquatic microcosms

“…(), Fierer et al . () and Mosher & Findlay () provide evidence that spatial variability in bacterial community composition within freshwater ecosystems is correlated with environmental variables including pH, bedrock type and water temperature. Thus the importance of niche‐related factors for the assembly of microbial communities is rarely disputed.…”

“…For this reason, species sorting is expected to result in relationships between taxon composition and environmental conditions, although the strength of these relationships is nevertheless impeded by either low, that is, dispersal limitation, or high dispersal rates, that is, mass effects ( Van der Gucht et al, 2007). Recent studies including Kent et al (2007), Fierer et al (2007) and Mosher & Findlay (2011) provide evidence that spatial variability in bacterial community composition within freshwater ecosystems is correlated with environmental variables including pH, bedrock type and water temperature. Thus the importance of niche-related factors for the assembly of microbial communities is rarely disputed.…”

The influence of geology and season on macroinvertebrates in Belizean streams: implications for tropical bioassessment

“…Geology and season are 2 of the most important environmental factors producing heterogeneity in macroinvertebrate assemblage composition and bioassessment output in temperate streams (Munné andPrat 2011, Neff andJackson 2011). Geological effects on macroinvertebrates have been related to variation in water chemistry (Olson 2012), food resources (Mosher and Findlay 2011), stream flow (Jin and Ward 2007), and water flow pathways (Barquín and Death 2006). Geology also influences habitat characteristics that are of direct significance to macroinvertebrate assemblages (Minshall 1984).…”

Colonization Habitat Controls Biomass, Composition, and Metabolic Activity of Attached Microbial Communities in the Columbia River Hyporheic Corridor

“…Several prior studies have demonstrated habitat-driven selection of hyporheic microbial communities, including ones in systems with different hydrology, substratum properties, organic matter inputs, or gradients in heavy-metal contamination (19)(20)(21)(22)(23)(24)(25)(26). Based on this work and recent microbial community assembly studies in the Hanford 300 Area HC (15)(16)(17), deterministic selection imposed by the various DOC sources/ amounts in the three different habitats was expected to lead to distinct microbial assemblages in the colonized sand materials.…”