Patterns in estuarine macrofauna body size distributions: The role of habitat a...

• Author(s): Dolbeth, Marina ; Raffaelli, Dave ; Pardal, Miguel A.
• Date: 2014
• Persistent ID: http://hdl.handle.net/10316/25269
• Origin: Estudo Geral - Universidade de Coimbra
• Subject(s): Body Mass; Benthic Macrofauna; Sedimentary Environments; Eutrophication; Resilience
• Document Type: Article
• Language: English

Description

Schwinghamer's (1981) habitat architecture hypothesis for body mass spectra in marine sediments predicts a single macrofauna mode in response to the bulk nature of the sediment. This proposition was examined for intertidal macrofauna from a well-studied estuarine system, using kernel density estimation to define modality and the locations of peaks and troughs. Three sedimentary environments and habitats were examined along a disturbance gradient related to eutrophication. Our results indicate that bimodality is likely to occur within the macrofauna size range, which weakens the habitat architecture model and casts doubts on the mechanisms behind other modes in benthic size spectra. The location of the modes and intervening trough were not conservative and not apparently related to sediment grain size or habitat structure, but somewhat dependent on the presence of particular species: the presence or absence of large numbers of individuals of Hydrobia ulvae and larger-bodied taxa such as Scrobicularia plana and Hediste diversicolor. Alternative competing hypotheses are explored for the observed results, including Warwick's (1984) phylogenetic explanation, but taking into consideration both species composition and disturbance impact, it seemsmost likely Holling's (1992) textural discontinuity hypothesis, as a measure of resilience, could be a plausible explanation. This research was supported by FCT (Portuguese Foundation for Science and Technology), through a grant attributed to M Dolbeth (SFRH/BPD/41117/2007) and BIOCHANGED project (PTDC/MAR/ 111901/2009), with funds from POPH (Portuguese Operational Human Potential Program), QREN Portugal (Portuguese National Strategic Reference Framework), andMCTES (PortugueseMinistry of Science, Technology, and Higher Education).