Spatial and temporal variations of bacterioplankton in the Chesapeake Bay: A re‐examination with high‐throughput sequencing analysis

Abstract

Chesapeake Bay is a large, dynamic, and productive temperate estuary, which plays an important role in transporting terrestrial materials into the Atlantic Ocean. The bacterioplankton communities experience strong environmental changes both seasonally and along the central axis of the Bay. The goal of this study was to explore the spatiotemporal and interannual patterns of the bacterioplankton communities in the estuary using high‐throughput sequencing of 16S rRNA genes. Deep sequencing uncovered many new bacterial groups not found in earlier studies, and showed that Chesapeake Bay contained highly diverse and dynamic bacterial communities. Bacterioplankton in the Bay in summer and autumn were more diverse and stable than those in winter and spring. The spatial pattern was overruled by strong temporal variations when the samples from all seasons were analyzed together. But, the spatial trend became more visible when samples were analyzed separately in individual seasons. Bacterial diversity indices decreased from the upper Bay to lower Bay. The spatial and temporal distributions of bacterioplankton were best explained by variations of salinity and temperature. In addition, nutrient availability (nitrogen and phosphorus), chlorophyll a, and light availability also contributed significantly to the spatiotemporal variation. Despite the interannual variation of the bacterioplankton communities, a stable and reoccurring spatiotemporal pattern was observed in the Chesapeake Bay, suggesting limited functional redundancy for planktonic estuarine microbiomes. Our results highlight the resilience of the planktonic bacterial communities in estuaries with long residence time, and different bacterial groups have unique responses/adaptation to dynamic environmental gradients.

Spatiotemporal Variations Dictate Stable and Resilient Microbiome Interactions in the Chesapeake Bay

“…Microbial interactions affected by temporal variations were also found in Alaska Beaufort Sea coast [51], the San Pedro Ocean Time-series station [91], and the Lake Mendota [93]. The higher number of nodes in the co-occurrence networks of warm season agrees with the previously reported high microbial diversity in the Bay [14,54]. High biodiversity are able to promote interactions between microbial communities [94], and these biotic interactions including competition, are commonly thought to increase co-occurrence in microbial networks as they refer to common resources and environmental conditions [30,95,96].…”

“…Similar to microbiome structures [14,54], microbial interactions and networks showed strong temporal and spatial patterns with distinct property and stability (Fig. 2-5 and Table 1).…”

“…Detailed description of sampling and environmental measurements have been described in previous studies [14,54]. Brie y, surface water samples were collected from the CB at seven stations along the middle axis in February/March, May/June, August, and October from 2003 to 2005 ( Fig.…”

“…Recently, we have characterized the microbial community structures across both temporal and spatial scales in the CB, where planktonic microbiomes were collected across seven sampling stations (along spatial and salinity gradients) in four seasons over three consecutive years [54]. In this study, we constructed co-occurrence networks based on the detailed 16S rRNA gene high-throughput sequences.…”

Distinct Distribution of Archaea From Soil to Freshwater to Estuary: Implications of Archaeal Composition and Function in Different Environments

“…One important factor to recognize from this study is that our conclusions are intertwined with the season or seasons in which they were sampled. Seasonal categories can have a major influence on microbial community composition within an environment (Wang et al, 2020). For example, Hullar et al (2005) identified phototrophic-driven seasonal shifts in epilithic bacteria communities collected at the same White Clay Creek site (Pennsylvania Piedmont) used for this study.…”