Influence of initial substratum surface tension on marine micro- and macro-fouling in the Gulf of Thailand

Abstract

The density of five major groups at fouling organisms Ibacteria, diatoms, choanotlagellates, ciliates, macroorganisms) on seven artilicial substrata with surface tensions between 19.0 and 64.5 mN m ' was studied in the Gulf at Thailand. Two series of test panels r the different substrata were immersed into the sea between 3 hours and 64 days (macrotauna 128 days). The results show that surface tension has ,t limited impact on the density of the organisms. Only bacteria settled conlinuously in signilicantly lower numbers on materials within the minimum bioadheslw2 range (20-25 mN m ') than on other substrata. Signifi(:dn[ differences between the substrata may disappear after long exposure, as in series 2 after 16days For diatoms and protozoa, a colonisation pattern similar to thdt of bacteria with a minimum ol 20-25 mN m : was detected alter severdl exposure intervals, l.lowever, it was never recor(ted m more than 3 exl)osure intervals in a row. The colonisation pattern of macroorganisms could not be attributed Io substratum surface tension. An index, called "colonisation degree" is introduced to give a gene.~ral impression at the density of organisms on the materials tested. The colonisation degree did not show any signilicant difference at any exposure interval. The present results clearly suggest that substratum surface tension is easily overshadowed by other factors in colonisation processes under natural conditions.

Barnacle settlement:field experiments on the influence of larval supply, tidal level, biofilm quality and age on Balanus amphitrite cyprids

“…This is in accordance with previous works focusing on experimental , Wieczorek et al 1995 or natural microbial biofilms (Hudon & Bourget 1981, Becker 1993, Becker et al 1997, Tsurumi & Fusetani 1998.…”

“…Physical cues known to influence cypris larvae involve salinity (Dineen & Hines 1994a,b), temperature (O'Connor & Richardson 1994, Kitamura & Nakashima 1996, light (Crisp & Barnes 1954, Raimondi 1990), wave strength (Raimondi 1990), benthic boundary layer flows (Crisp 1955, Wethey 1986, Mullineaux & Butman 1991, Mullineaux & Garland 1993, Judge & Craig 1997 and the characteristics of the surface: physico-chemistry (Raimondi 1988b, Holmes et al 1997), surface energy (Rittschof Costlow 1989a;b, Roberts et al 1991, Maki et al 1992, Becker 1993, O'Connor & Richardson 1994, Becker et al 1997, Holmes et al 1997, vibration , Rittschof et al 1998, texture (Crisp & Barnes 1954, Letourneux & Bourget 1988, Raimondi 1990, Hills & Thomason 1996, 1998a and small-scale heterogeneity (Bergeron & Bourget 1986, Chabot & Bourget 1988, Walters 1992, Lernire & Bourget 1996, Miron et al 1996, Walters & Wethey 1996.…”

“…Habitat selection is influenced by boundary layer structure (Crisp 1955, Wethey 1986, Mullineaux & Butman 1991, Mullineaux & Garland 1993, Judge & Craig 1997, the nature of the surface (physico-chemistry: Raimondi 1988b, Holmes et al 1997surface energy: Rittschof & Costlow 1989a,b, Roberts et al 1991, Maki et al 1992, Becker 1993, O'Connor & Richardson 1994, Becker et al 1997, Holmes et al 1997vibrations: Branscomb & Rittschof 1984, Rittschof et al 1998texture: Crisp & Barnes 1954, Letourneux & Bourget 1988, Raimondi 1990, Hills & Thomason 1996, 1998a; and small-scale heterogeneity: Bergeron,& Bourget 1986, Chabot & Bourget 1988, Walters 1992, Gregoire & Bourget 1996, Lemire & Bourget 1996, Miron et al 1996, Walters & Wethey 1996, substratum biological cues (associated with the presence of natural biofilms: Hudon & Bourget 1981, Letourneux & Bourget 1988& Todd 1-998; conspecific adults: Knight-Jones--1-953, Rittschof et al 1984, &ttschof 1985, Gabbott & Larman 1987, Letourneux & Bourget 1988, Chabot & Bourget 1988, Raimondi 1988a…”

Relevance of crustacean carapace wettability for fouling

“…Distance weighted least square line fit of carapace wettability and densities of bacteria (3a), diatoms (3b), protozoa (3c) and fungi (3d). Becker et al, 1997). Both artificial materials became (U-test: p < 0.05) much more densely colonised by all groups of foulers within 5-8 days of exposure than carapaces of corresponding wettability.…”

“…Despite some promising results in antifouling research (Dexter, 1979;Bultmann et al, 1984;Fletcher & Baier, 1984;Rittschof & Costlow, 1989;Roberts et al, 1991;Lindner, 1992), there is some doubt about the efficiency of surface wettability as an antifouling mechanism under natural conditions (Becker, 1993;Becker et al, 1997). Wettability effects may be easily dwarfed by other abiotic factors and biological interactions under natural conditions.…”