Bioturbation functional roles associated with mangrove development in French Guiana, South America

Abstract

OATAO is an open access repository that collects the work of Toulouse researchers and makes it freely available over the web where possible. This is an author-deposited version published in : http://oatao.univ-toulouse.fr/ Eprints ID : 17613 Any correspondence concerning this service should be sent to the repository administrator: staff-oatao@listes-diff.inp-toulouse.fr Abstract This study aims to qualify, quantify, and compare the sediment reworking rates induced by the meso-(0.25-1 mm) and macro-infauna ([1 mm) along a mangrove growth gradient in the sedimentary dynamics of the French Guiana coast. The characterization of the role of small-infauna bioturbation in mangroves is new despite their known numerical dominance in tropical environments. Bare sediment, pioneer mangroves, and young mangroves were investigated during the dry season and spring tide to characterize their environment, infaunal functional community structure and sediment reworking rates. The biodiffusion differed significantly between mangrove stages, co-varying mainly with density and functional richness. On the contrary, the non-local transport remained similar, despite the mangrove-agespecificity of infauna functional compositions, which responded to modifications in the nature and content of organic matter. The first mangrove infaunal functional sequence is described: organisms that first colonize deposited mud generate the maximum biodiffusive mixing and induce a total downward particle flux (BDF) as high as in the young mangroves; in the pioneer mangroves, the infauna variables and BDF are stressed to minimum values. Our study sheds light on the functional contribution of the small infauna in a mangrove coastal area and quantifies its role in particle transport during mangrove development.

First Assessment of the Benthic Meiofauna Sensitivity to Low Human-Impacted Mangroves in French Guiana

“…Several studies demonstrate that meiofauna (32 µm-1 mm), besides being fundamental to understand the structure and functioning of marine communities, can be used as an additional proxy for responses of benthic communities to environmental changes and can be a useful tool to investigate anthropogenic impacts, reflect spatial and temporal changes, and describe and document the good ecological status of soils and sediments ( [21] and references therein). Meiofauna is the most abundant and diversified benthic component into mangroves sediments providing important ecosystem benefits such as sediment bioturbation activities stimulating the recycling of organic matter [22][23][24][25] and trophic food webs [26,27]. Meiofauna abundance and community structure are shaped by sediments physical and biogeochemical characteristics and are rapidly affected by environmental changes, making this benthic component potentially suitable for biomonitoring [21].…”

Assessing the relationship between macro-faunal burrowing activity and mudflat geomorphology from UAV-based Structure-from-Motion photogrammetry

“…These muddy deposits and their colonizing mangroves dissipate wave energy, enabling further progressive muddy coastal accretion. Ap Brunier et al Remote Sensing of Environment xxx (xxxx) xxx-xxx parently uniform and monotonous at a large-scale, the muddy intertidal substrate is difficult to access in the field and characterised by centimetre-scale spatial habitat and biogeomorphic variability (Anthony et al, 2008(Anthony et al, , 2014Proisy et al, 2009;Aschenbroich et al, 2016Aschenbroich et al, , 2017. These two aspects limit the possibilities of characterisation of benthic variables, even when high-resolution and accurate surface-mapping techniques such as RTK-DGPS, terrestrial LiDAR (TLS), or a total station are used.…”

Quantifying bioturbation across coastal seascapes: Habitat characteristics modify effects of macrofaunal communities

“…Understanding the drivers of bioturbation and variations in its intensity is key for assessing how coastal systems act as critical biogeochemical transition zones. However, quantitative data on bioturbation across natural environmental gradients are rare (Wheatcroft and Martin 1996, Sturdivant et al 2012, Aschenbroich et al 2017, impeding our mechanistic understanding of this important process.…”