Colonization of diatoms and bacteria on artificial substrates in the northeastern coastal Adriatic Sea

Mejdandžić, Maja; Ivanković, Tomislav; Pfannkuchen, Martin; Godrijan, Jelena; Marić Pfannkuchen, Daniela; Hrenović, Jasna; Ljubešić, Zrinka (2015) Colonization of diatoms and bacteria on artificial substrates in the northeastern coastal Adriatic Sea. Acta Botanica Croatica, 74 (2). pp. 407-422. ISSN 0365-0588

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Abstract

Every surface that is immersed in seawater becomes rapidly covered with an unavoidable biofilm. Such biofilm formation, also known as fouling, is a complex multistage process and not yet thoroughly investigated. In this study, the succession of diatoms and bacteria was investigated during a one month exposure on an artificial substrate of plexiglass (polymer of methyl methacrylate) mounted above the seafloor at a depth of 5 m. For biofilm analyses, the fouling was investigated using selective agar plates, epifluorescence, light and electronic microscopy, as well as high performance liquid chromatography (HPLC) pigment analysis. During biofilm development, the abundance of all biofi lm components increased and reached maximum values after a one month exposure. In the bacterial community, heterotrophic marine bacteria were dominant and reached 1.96 ± 0.79 × 104 colony forming units (CFU) cm–2. Despite the fact that faecal coliforms and intestinal enterococci were detected in the water column, faecal coliforms were not detected in the biofilm and intestinal enterococci appeared after one month of exposure but in the negligible number of 60 ± 10 CFU cm–2. The phototrophic component of the biofilm was dominated by diatoms and reached a concentration of 6.10 × 105 cells cm–2, which was supported by pigment analysis with fucoxanthin as dominant pigment in a concentration up to 110 ng cm–2. The diatom community was dominated by Cylindrotheca closterium and other pennate benthic diatoms. A detailed taxonomic analysis by electronic microscopy revealed 30 different taxa of diatoms. The study confirmed that a plexiglass surface in a marine environment is susceptible to biofouling within 30 days of contact. Furthermore, the colonization process sequence firstly involved bacteria and cyanobacteria, and secondly diatoms, which together formed a primary biofilm in the sea.

Item Type:

Article

Uncontrolled Keywords:

bacteria; biofilm; biofouling; diatoms; succession

Subjects:

NATURAL SCIENCES > Geology

Divisions:

Center for Marine Research

Projects:

Project title	Project leader	Project code	Project type
Bio-tracing Adriatic water masses (BIOTA) (Bioindikatori vodenih masa u Jadranu)-BIOTA	Zrinka Ljubešić	UIP-11-2013-6433	HRZZ
Structure and development of microalgal communities in a trophic gradient (Struktura i razvoj zajednica mikroalga u trofičkom gradijentu)	Damir Viličić	119-1191189-1228	MZOS
Interaction of mineral carriers and phosphate-removing bacteria in wastewaters (Međuodnos mineralnih nosača i fosfat-uklanjajućih bakterija u otpadnim vodama)	Jasna Hrenović	119-1191155-1203	MZOS
Mechanism of long-term changes in the northern Adriatic ecosystem (Mehanizam dugoročnih promjena u ekosustavu sjevernog Jadrana)	Robert Precali	098-0982705-2731	MZOS