Influence of diatom exopolymers and biofilms on metamorphosis in the barnacle Balanus amphitrite

Abstract

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 301:231-245 (2005) - doi:10.3354/meps301231 Influence of diatom exopolymers and biofilms onmetamorphosis in the barnacle Balanus amphitrite Jagadish S. Patil, Arga Chandrashekar Anil* Marine Corrosion and Materials Research Division, National Institute of Oceanography, Dona Paula, Goa 403 004, India *Email: acanil@darya.nio.org ABSTRACT: Natural biofilms constitute a complex network of microorganisms (bacteria, diatoms, protozoa, fungi) and their extracellular polymeric substances (EPS), which influence settlement in benthic invertebrates. We investigated the influence of diatom (Bacillariophyceae) films and EPS (>1000 molecular weight) on metamorphosis in the acorn barnacle Balanus amphitrite Darwin, a dominant fouling organism, using axenic and non-axenic films, and free and biofilm EPS, of 5 species of pennate diatoms: Amphora coffeaeformis and A. rostrata, and Navicula transitans var. derasa f. delicatula, N. crucicula and N. subinflata. Fourier-transformed infrared spectroscopy (FTIR) spectra revealed that the EPS produced by diatoms are of similar nature; however, the proportion of monosaccharides varies with species, indicating a potential role for influencing larval metamorphosis. Free EPS of axenic diatoms had no effect, whereas biofilm EPS induced larvae to metamorphose. Amphora spp. produced more biofilm EPS, but had relatively weaker effects than Navicula spp. Axenic diatom films also facilitated larval metamorphosis (depending on species and cell density) in some cases, suggesting that the cues provided by the diatoms themselves can also mediate invertebrate larval metamorphosis in the absence of microbial films. Non-axenic diatom films (which had higher cell densities) and biofilm EPS promoted metamorphosis to a greater degree than those of axenic diatoms. Enhancement of metamorphosis depended on diatom species and on their density in the films, as well as on the composition of their EPS. Differential responses of barnacle larvae to different diatom species and their EPS indicate that each diatom species provides a different set of physico-chemical signals to settling larvae. KEY WORDS: Diatoms · Bacillariophyceae · Extracellular polymeric substances · Biofilms · Larvae · Balanus amphitrite Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 301. Online publication date: October 11, 2005 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2005 Inter-Research.