Drift in ocean currents impacts intergenerational microbial exposure to temperature

Abstract

Microbes are the foundation of marine ecosystems [Falkowski PG, Fenchel T, Delong EF (2008) Science 320(5879): [1034][1035][1036][1037][1038][1039]. Until now, the analytical framework for understanding the implications of ocean warming on microbes has not considered thermal exposure during transport in dynamic seascapes, implying that our current view of change for these critical organisms may be inaccurate. Here we show that upper-ocean microbes experience along-trajectory temperature variability up to 10°C greater than seasonal fluctuations estimated in a static frame, and that this variability depends strongly on location. These findings demonstrate that drift in ocean currents can increase the thermal exposure of microbes and suggests that microbial populations with broad thermal tolerance will survive transport to distant regions of the ocean and invade new habitats. Our findings also suggest that advection has the capacity to influence microbial community assemblies, such that regions with strong currents and large thermal fluctuations select for communities with greatest plasticity and evolvability, and communities with narrow thermal performance are found where ocean currents are weak or along-trajectory temperature variation is low. Given that fluctuating environments select for individual plasticity in microbial lineages, and that physiological plasticity of ancestors can predict the magnitude of evolutionary responses of subsequent generations to environmental change [Schaum CE, Collins S (2014) Proc Biol Soc 281(1793):20141486], our findings suggest that microbial populations in the sub-Antarctic (∼40°S), North Pacific, and North Atlantic will have the most capacity to adapt to contemporary ocean warming. microbial ecology | plankton | advection | evolution | plasticity

The Role of Ocean Currents in the Temperature Selection of Plankton: Insights from an Individual-Based Model

“…Equatorward-flowing currents, like the Falkland Current and Canary Current, have negative differential. These global patterns are also qualitatively similar to those for temperature offsets for drift of planktic foraminifera presented by van Sebille et al [26] and the inter-generational temperature ranges due to drift experienced by microbes presented by Doblin and van Sebille [28]. However, these two previous studies did not explicitly consider fitness and selection.…”

“…The role of ocean currents on the temperature record incorporated into the shells of planktic foraminifera has been recognized and quantified using modeling [26, 27]. Over several generations, currents can move microbes across different temperature regions, which increases the range of temperatures they experience by up to 10°C, compared to the seasonal fluctuation at one location [28]. Therefore, the role of currents in ocean microbe biogeography is well-recognized.…”

Evidence for environmental and ecological selection in a microbe with no geographic limits to gene flow

“…Correlation between population structure and temperature is not entirely surprising. Temperature is an important factor regulating phytoplankton growth rates both between and within species, and likely plays a role in regulating dispersal capacity (51,52).…”

Highlighting patterns of fungal diversity and composition shaped by ocean currents using the East China Sea as a model

“…Microorganisms can travel long distances by hitchhiking on ocean currents, influencing microbial community assemblies (Brum et al., ; Doblin & van Sebille, ) from prokaryotes (Hamdan et al., ; Zhao et al., ) to microeukaryotes (Pernice et al., ). Previous studies have reported algae and plankton as intruders in the ECS through the KSWM (Dai et al., ; Hsieh et al., ).…”