A trait-based approach to planktonic foraminifera ecology and biogeography

Abstract

Despite the importance of planktonic foraminifera in carbonate production and
palaeoceanography as zooplankton calcifiers with well-preserved fossil record, our knowledge regarding their ecology is limited. This study aims to a mechanistic understanding of foraminifera ecology and biogeography through the trait approach. The two first trait-based ecosystem models which consider foraminifera part of a plankton community have been developed; a 0-D and a 3-D (ForamEcoGEnIE). Shell size, calcification, passive feeding strategy and larger apparent size due to spines have been foraminifera’s studied traits. Calcification is represented with energy loss (reduction in growth) and protection (reduction in predation and mortality). The 0-D model has been used for studying two life
stages of foraminifera (prolocular, adult) under nine different environments. With
ForamEcoGEnIE the biogeography of adult non-spinose foraminifera under present and future climate conditions have been explored. The energetic needs of calcification varied from 10% to 60% reduction in growth depending on the life stages, populations (spinose, nonspinose) and modelled environments. The models suggested a combination of foraminifera low biomass and shell as a protection from predation. Applying a required reduction in mortality indicated that foraminifera could use the shell as protection for other reasons than
predation like pathogens. Following the observations, in the presented models carnivorous diet was more efficient in oligotrophic regions, while herbivorous in cold waters. A further investigation on species diet and encounter rates is needed for a deeper understanding of their biogeography. ForamEcoGEnIE showed that the traits of size, calcification and herbivorous diet could successfully capture the main biogeographical patterns of non-spinose species. ForamEcoGEnIE projected an increase of foraminifera biomass in subpolar regions and a reduction elsewhere by 2100. This study delivered novel insights on planktonic
foraminifera ecology, and two new foraminifera models which can be used as methods tools for studying foraminifera ecology under different climate conditions.

Date of Award	12 May 2020
Original language	English
Awarding Institution	University of Bristol
Supervisor	Daniela N Schmidt (Supervisor), Fanny M Monteiro (Supervisor) & Andy J Ridgwell (Supervisor)