Abstract
Rather than spatial means of biomass, observed overlap in the intermittent spatial distributions of aquatic predators and prey is known to be more important for determining the flow of nutrients and energy up the food chain. A few previous studies have separately suggested that such intermittency enhances phytoplankton growth and trophic transfer to sustain zooplankton and ultimately fisheries. Recent observations have revealed that phytoplankton distributions display consistently high degrees of mm scale patchiness, increasing along a gradient from estuarine to open ocean waters. Using a generalized framework of plankton ecosystem models with different trophic configurations, each accounting for this intermittency, we show that it consistently enhances trophic transfer efficiency (TE), i.e. the transfer of energy up the food chain, and expands the model stability domain. Our results provide a new explanation for observation-based estimates of unexpectedly high TE in the vast oligotrophic ocean and suggest that by enhancing the viable trait space, micro-scale variability may potentially sustain plankton biodiversity.
Highlights
Rather than spatial means of biomass, observed overlap in the intermittent spatial distributions of aquatic predators and prey is known to be more important for determining the flow of nutrients and energy up the food chain
Recent observations have revealed ubiquitous intermittency in phytoplankton distributions at the micro scale[8,9,10,11], and a few recent modelling studies have suggested that this micro-scale variability impacts plankton ecosystem dynamics and biodiversity[12,13,14]
Using a generalized plankton ecosystem modelling framework, including models of differing trophic complexity and with different grazing functional responses, we investigate how micro-scale variability affects plankton biodiversity and ecosystem function
Summary
Rather than spatial means of biomass, observed overlap in the intermittent spatial distributions of aquatic predators and prey is known to be more important for determining the flow of nutrients and energy up the food chain. We apply the closure modelling approach to test the functional forms often assumed in ecosystem models against observed micro-scale intermittency as quantified www.nature.com/scientificreports by the coefficient of variation (CV) (ratio of standard deviation to mean) of the micro-scale fluorescence field, which is a proxy for phytoplankton biomass With both saturating and non-saturating grazing functions and in all model configurations considered, we find that micro-scale variability consistently supports the highest trophic level present, i.e. enhances trophic transfer efficiency (TE), and expands the model stability domain, potentially sustaining biodiversity by allowing species with a wider range of trait values to coexist
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