Oceanographic boundaries constrain microbial diversity gradients in the South Pacific Ocean

Abstract

Marine microbes along with microeukaryotes are key regulators of oceanic biogeochemical pathways. Here we present a high-resolution (every 0.5° of latitude) dataset describing microbial pro- and eukaryotic richness in the surface and just below the thermocline along a 7,000-km transect from 66°S at the Antarctic ice edge to the equator in the South Pacific Ocean. The transect, conducted in austral winter, covered key oceanographic features including crossing of the polar front (PF), the subtropical front (STF), and the equatorial upwelling region. Our data indicate that temperature does not determine patterns of marine microbial richness, complementing the global model data from Ladau et al. [Ladau J, et al. (2013) ISME J 7:1669-1677]. Rather, NH, nanophytoplankton, and primary productivity were the main drivers for archaeal and bacterial richness. Eukaryote richness was highest in the least-productive ocean region, the tropical oligotrophic province. We also observed a unique diversity pattern in the South Pacific Ocean: a regional increase in archaeal and bacterial diversity between 10°S and the equator. Rapoport's rule describes the tendency for the latitudinal ranges of species to increase with latitude. Our data showed that the mean latitudinal ranges of archaea and bacteria decreased with latitude. We show that permanent oceanographic features, such as the STF and the equatorial upwelling, can have a significant influence on both alpha-diversity and beta-diversity of pro- and eukaryotes.

Diversity and composition of intertidal gastropod microbiomes across a major marine biogeographic boundary

“…This differs from previous studies of host-associated marine microbial communities, where alpha diversity significantly differed between collection sites (Luter et al, 2015;Pantos et al, 2015). Similarly, pelagic microbial diversity has been shown to change across major oceanographic boundaries (Raes et al, 2018). Thus, our results suggest that marine biogeographic boundaries may affect the diversity of intertidal gastropod-associated microbial communities differently from that of other groups.…”

“…Little is known at present about the role of marine biogeographic boundaries in structuring spatial patterns of microbial species richness and composition, but a recent study suggests that richness of free‐living bacterial, archaeal and microeukaryotic taxa can change across oceanographic boundaries (Raes et al . ).…”

“…Thus, populations of the host species at our site north of PtC (Jalama Beach County Park, Lompoc, CA (JB; 34.5131 N, −120.5041 W)) experience very different environmental conditions compared with our site south of this boundary (Scripps Coastal Reserve, La Jolla, CA (SIO; 32.8661 N, 117.2543 W)). Little is known at present about the role of marine biogeographic boundaries in structuring spatial patterns of microbial species richness and composition, but a recent study suggests that richness of free-living bacterial, archaeal and microeukaryotic taxa can change across oceanographic boundaries (Raes et al 2018).…”

Where the Ecological Gaps Remain, a Modelers' Perspective

“…Nevertheless, recent advances in process-based macroecology (Cabral et al, 2017;Connolly et al, 2017) and trait-based approaches (Kiørboe et al, 2018) are making advances in terms of dynamic prediction of macroecological patterns, including across scales. Isotopic methods are helping bridge the trophic gaps at larger spatial and temporal scales (Hobson et al, 2010;Quillfeldt et al, 2010) and new metagenomic methods are being used to generate new ecosystem scale maps of active processes and biodiversity (Raes et al, 2018). As we outline above, nested network approaches are also helping to link understanding of interactions and connectivity across processes, space, and time (Pilosof et al, 2017).…”

Metabolic pathways inferred from a bacterial marker gene illuminate ecological changes across South Pacific frontal boundaries

“…Recent metagenomics and metatranscriptomics work from the Tara Oceans Project suggested that, in polar regions, the effects of ocean warming on bacterial communities will be stronger on a community (composition) level than on a gene (regulatory) level 6 . On a basin scale, Raes, Bodrossy 7 showed that permanent oceanographic frontal systems can have a signi cant in uence on both the alpha-and beta-diversity of prokaryotes and microbial eukaryotes. In addition, their data supported a strong positive link between productivity and microbial diversity.…”