Mangrove microbial diversity and the impact of trophic contamination

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 : 11082 b s t r a c tMangroves are threatened ecosystems that provide numerous ecosystem services, especially through their wide biodiversity, and their bioremediation capacity is a challenging question in tropical areas. In a mangrove in Mayotte, we studied the potential role of microbial biofilm communities in removing nutrient loads from pre-treated wastewater. Microbial community samples were collected from tree roots, sediments, water, and from a colonization device, and their structure and dynamics were compared in two areas: one exposed to sewage and the other not. The samples from the colonization devices accurately reflected the natural communities in terms of diversity. Communities in the zone exposed to sewage were characterized by more green algae and diatoms, higher bacteria densities, as well as different compositions. In the area exposed to sewage, the higher cell densities associated with specific diversity patterns highlighted adapted communities that may play a significant role in the fate of nutrients.

Antifouling Coatings Influence both Abundance and Community Structure of Colonizing Biofilms: a Case Study in the Northwestern Mediterranean Sea

“…While this technique is extensively used for marine planktonic communities, especially for picoplankton enumeration, only three recent articles have reported its use for marine biofilms (22)(23)(24), and none of them are related to AF coatings. FCM has the advantage of providing accurate cell abundances for the different subcommunities evidenced by their optical properties, which is not possible with either fingerprinting or deep-sequencing approaches.…”

“…Cyanobacteria are especially known to quickly release their pigments (phycoerythrin or phycocyanin) when they start to degrade. It is interesting that in analyses of biofilms that displayed overall low densities after short immersion times (3 days [22] and 8 days [24]) or of biofilms developed in 3 weeks but in a cold immersion site (23), no pretreatment step was performed. It should be noted that in previous studies by Bouchez et al (24) and Toupoint et al (23), only one group of picocyanobacteria was mentioned.…”

“…Until now, prokaryotic diversity in marine biofilms on artificial surfaces has been addressed only by using fingerprinting or fluorescence in situ hybridization (FISH) (e.g., see references 9, 19, and 24), cloningsequencing (11), or PhyloChip (10) studies, and AF coatings were investigated only by using culture-dependent (30,57) or fingerprinting (19,35) approaches. As far as eukaryote diversity is concerned, Bouchez et al (24) reported various community patterns according to nutrient availability by using a 18S rRNA gene-based fingerprinting approach. Only Toupoint et al (23), using cloning-sequencing approaches, reported organisms other than diatoms (mainly ciliates, dinoflagellates, and Chlorophyceae).…”

“…Fluorescence in situ hybridization (FISH) was used mainly for relative quantification of classes or specific groups of bacterial taxa (7,9,12,18), as was quantitative PCR (qPCR) (19)(20)(21). Only very recently were relative abundances of (picocyano)bacteria and pico-and nanoeukaryotes from biofilm on glass determined by using flow cytometry (FCM) (22)(23)(24). Microphytobenthos in marine biofilms on artificial surfaces appears to be represented mainly by diatoms and especially pennates.…”

“…Diatoms especially dominate these biofilms, which adhere tenaciously to hydrophobic surfaces and are not released from FRC, even on vessels operating at high speeds (Ͼ30 knots) (28). Considering the difficulty in bacterial enumeration when bacteria are embedded in biofilms, their abundance on AF coatings has been reported rarely, and when they have been reported, the analyses were based mostly on microscopy observation (16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30). Successful colonization of all coatings by bacteria soon after immersion has been reported, and significant differences were observed, depending on the coatings and the immersion sites.…”