Abstract
Marine protists are highly heterogeneous and play key roles in the structure and functioning of marine ecosystems. However, little is known on the underlying biogeographic processes and seasonal diversity patterns that shape their community assembly in a regional scale in marginal sea. In this study, we conducted high-throughput sequencing of 18S rRNA gene to survey the protist community compositions (PCCs) of the Changjiang (Yangtze River) plume, an intensely human-affected coastal area, to the adjacent continental shelf waters over three seasons. Furthermore, the different impacts of environmental and spatial factors on marine PCCs were examined. The results revealed significant dissimilarities of PCC’s diversity among seasons and habitats, with more obvious seasonal variations in the Changjiang plume. Procrustes analysis showed better consistency of the community-environment relationship in shelf area, further supported by stronger correlation coefficients computed in the Mantel tests. This might be explained by seasonal dynamics of Changjiang Diluted Waters (i.e., the mixing of the Changjiang runoff with inshore water of the East China Sea) that changed the environmental conditions of coastal area dramatically, resulting in lower importance of spatial factors (dispersal limitation) on PCCs compared with environmental filters, including physicochemical properties (e.g., water temperature, salinity, dissolved oxygen, and nutrients), as well as biotic factors (e.g., Chl a and food abundance). This was further explained by higher immigration rate and fitness to neutral model, which suggested a predominant role of neutral process in shaping the PCCs in coastal area. Different richness, diversity, and taxonomic compositions but comparable biogeographic patterns were observed among abundant and rare sub-communities. In general, the abundant sub-communities exhibited higher dispersal ability which tend to respond to environmental selection during dispersal, whereas the rare sub-communities appeared to be present only in few samples due to dispersal limitation. Co-occurrence network further indicated the importance of biotic interactions in community assembly and potential roles of rare taxa in maintaining the community structure. Overall, this study suggests the dynamic in the biogeographic patterns of PCCs of the Changjiang plume to the adjacent waters in the ECS responding with the changing environmental conditions and geographical factors.
Highlights
Protists are significant components in global marine ecosystems with wide distributions and high biodiversity in multiple trophic modes, which play fundamental roles in numerous essential ecological and biogeochemical processes (Adl et al, 2012; Caron et al, 2012; Fuhrman et al, 2015; Keeling and del Campo, 2017)
The other category is the stochastic process supported by neutral theory (Hubbell, 2006), suggesting that the biogeographic distribution patterns of the community are affected by random processes such as dispersal effect restricted by spatial distance, ecological or genetic drift, and accidental or historical events (Martiny et al, 2006; Hanson et al, 2012)
This study provides a comprehensive description on the diversity, community structure, and biogeographic processes of abundant and rare marine protists in the Changjiang plume and its adjacent shelf area, considering scales of time and space
Summary
Protists (single-celled eukaryotes) are significant components in global marine ecosystems with wide distributions and high biodiversity in multiple trophic modes, which play fundamental roles in numerous essential ecological and biogeochemical processes (Adl et al, 2012; Caron et al, 2012; Fuhrman et al, 2015; Keeling and del Campo, 2017). The other category is the stochastic process supported by neutral theory (Hubbell, 2006), suggesting that the biogeographic distribution patterns of the community are affected by random processes such as dispersal effect restricted by spatial distance (known as dispersal limitation), ecological or genetic drift, and accidental or historical events (Martiny et al, 2006; Hanson et al, 2012). Time and space are the two major scales over which the microbial community composition changes in response to heterogeneous environment and at different spatial scales (Fuhrman et al, 2015; Langenheder and Lindström, 2019). Both the environmental and spatial factors should be considered when determining the PCCs assembly in different time and space scales
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call