Cannibalism makes invasive comb jelly, Mnemiopsis leidyi, resilient to unfavourable conditions

Jamileh Javidpour,Juan-Carlos Molinero,Patrick Roberts,Thomas Larsen,Eduardo Ramírez-Romero

doi:10.1038/s42003-020-0940-2

Abstract

The proliferation of invasive marine species is often explained by a lack of predators and opportunistic life history traits. For the invasive comb jelly Mnemiopsis leidyi, it has remained unclear how this now widely distributed species is able to overcome long periods of low food availability, particularly in their northernmost exotic habitats in Eurasia. Based on both field and laboratory evidence, we show that adult comb jellies in the western Baltic Sea continue building up their nutrient reserves after emptying the prey field through a shift to cannibalizing their own larvae. We argue, that by creating massive late summer blooms, the population can efficiently empty the prey field, outcompete intraguild competitors, and use the bloom events to build nutrient reserves for critical periods of prey scarcity. Our finding that cannibalism makes a species with typical opportunistic traits more resilient to environmental fluctuations is important for devising more effective conservation strategies.

Highlights

The proliferation of invasive marine species is often explained by a lack of predators and opportunistic life history traits
We carried out a daily high frequency sampling of M. leidyi and their prey in Kiel Fjord (Fig. 1) in August and September 2008, the period before and after bloom collapse
Abundance and total specimen size of M. leidyi peaked around the 245th day of the year (September 1, Fig. 2A, B), seven days after the abundance peak of mesozooplankton, the main prey for adults, but ten days before the peak of microzooplankton, the main prey for larval M. leidyi (Fig. 2D)

Summary

Introduction

The proliferation of invasive marine species is often explained by a lack of predators and opportunistic life history traits. For the invasive comb jelly Mnemiopsis leidyi, it has remained unclear how this widely distributed species is able to overcome long periods of low food availability, in their northernmost exotic habitats in Eurasia Based on both field and laboratory evidence, we show that adult comb jellies in the western Baltic Sea continue building up their nutrient reserves after emptying the prey field through a shift to cannibalizing their own larvae. A shift from interspecific to intraspecific predation in late summer allowed the adult population to build its nutrient reserves during a period where their basal metabolism is very high We posit that this strategy confers a fitness advantage in regions with long and cold winters, and that cannibalism may be a key trait behind M. leidyi’s success in establishing permanent populations in its northernmost exotic habitats

Methods

Results

Conclusion