Trophic interactions drive the emergence of diel vertical migration patterns: a game-theoretic model of copepod communities

Abstract

Diel vertical migration (DVM), the daily movement of organisms through oceanic water columns, is mainly driven by spatio-temporal variations in the light affecting the intensity of predator–prey interactions. Migration patterns of an organism are intrinsically linked to the distribution of its conspecifics, its prey and its predators, each with their own fitness-seeking imperatives. We present a mechanistic, trait-based model of DVM for the different components of a pelagic community. Specifically, we consider size, sensory mode and feeding mode as key traits, representing a community of copepods that prey on each other and are, in turn, preyed upon by fish. Using game-theoretic principles, we explore the optimal distribution of the main groups of a planktonic pelagic food web simultaneously. Within one single framework, our model reproduces a whole suite of observed patterns, such as size-dependent DVM patterns of copepods and reverse migrations. These patterns can only be reproduced when different trophic levels are considered at the same time. This study facilitates a quantitative understanding of the drivers of DVM, and is an important step towards mechanistically underpinned predictions of DVM patterns and biologically mediated carbon export.

Body size‐ and season‐dependent diel vertical migration of mesozooplankton resolved acoustically in the San Diego Trough

“…Daytime depths and vertical migration speeds of large, intermediate, and small scatterers differed, with progressively shallower depths, smaller DVM amplitudes, and slower migration speeds with diminishing size. The increased DVM amplitudes of larger‐bodied organisms are in agreement with previous net‐based studies (Steinberg et al 2008; Ohman and Romagnan 2016) and model predictions (Pinti et al 2019) for different sized copepods. In experimental mesocosms, copepods increased their daytime depth and amplitude with increasing developmental stage and size (Huntley and Brooks 1982).…”

“…Experimental assessment of size-and taxonspecific light responses is needed to address this issue. Previous studies have found the optical attenuation coefficient (Ohman and Romagnan 2016;Pinti et al 2019) and water clarity (Steinberg et al 2008) to be related to DVM amplitude and residence depths.…”

“…The depth at which organisms of different body sizes reside can also reflect their predation risk (Ohman and Wood 1996; Hirst and Kiørboe 2002). The size‐dependent mortality risk from visual predators in surface waters is modulated by the availability of light (De Robertis et al 2000; Pinti et al 2019).…”

Linking plankton size spectra and community composition to carbon export and its efficiency

“…Implementing vertical migrations may be done through optimisation (e.g. Brun et al, 2019; Pinti et al, 2019; Pinti & Visser, 2019). However, implementing behaviour together with population dynamics is challenging, especially if considered at the global scale.…”

Model estimates of metazoans’ contributions to the biological carbon pump

“…Higher trophic levels have their own imperative to organise their vertical migration to take advantage of their migrating prey while avoiding predators. DVM within a marine pelagic community is therefore the product of a co-adaptive game where many animals seek to optimize their migration patterns relative to the migration patterns of their respective prey, predators and con-specifics ( 6 –8 ).…”