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In this study, Soda Lime Glass (SLG) and Stainless Steel (SS316L) substrata coated with Titanium oxide (TiOx) were tested for their efficacy in the laboratory microcosms and in field against micro- and macrofouling. Laboratory microcosm studies were conducted for five days using natural biofilms, single-species diatom (Navicula sp.), and bacterial biofilms, whereas field observations were conducted for 30 days. The TiOx-coating induced change in the mean contact angle of the substratum and rendered SS316L more hydrophilic and SLG hydrophobic, which influenced the Navicula sp. biofilm, and bacterial community structure of the biofilm. Overall, the TiOx-coated SS316L showed minimal microfouling, whereas non-coated SLG exhibited greater efficacy in deterring/preventing macrofouling organisms. Moreover, the reduction in macrofouling could be attributed to high abundance of Actinobacteria. Unraveling the mechanism of action needs future studies emphasizing biochemical processes and pathways. [ABSTRACT FROM AUTHOR]

Identification of marine invertebrate larvae using morphological characters is laborious and complicated by phenotypic plasticity. Balanus amphitrite is a dominant barnacle, important in the context of intertidal ecology and biofouling of manmade structures. Morphological identification of barnacle larval forms in a mixed population is difficult because of their intricacy and similarity in size, shape and developmental stages. We report the development and application of a nucleic acid-based Polymerase Chain Reaction (PCR) method for the specific identification of the barnacle, B. amphitrite, from the heterogeneous zooplankton sample. This method is reliable and accurate thereby overcoming taxonomic ambiguity. Sequence alignment of the 18S rRNA gene region of selected species of barnacles allowed the design of B. amphitrite-specific PCR primers. Assay specificity was evaluated by screening DNA obtained from selected species of barnacles. The oligonucleotide primers used in the study flanked a 1600 bp region within the 18S rRNA gene. The primer is specific and can detect as few as 10 individuals of B. amphitrite larvae spiked in a background of ~186 mg of zooplankton. This technique facilitates accurate identification and the primer can be used as a marker for enumeration of B. amphitrite larvae in the plankton. [ABSTRACT FROM PUBLISHER]

The impact of diatom food species (Chaetoceros calcitrans and Skeletonema costatum), temperature and starvation on the larval development of Balanus amphitrite was evaluated. Starvation threshold levels for different ages of larvae (0- to 5-day-old) fed with C. calcitrans and S. costatum and then starved at 5, 15 and 25 °C temperature were estimated as ultimate recovery hour (URH; denoting the starvation point in hours at the end of which larvae can recover and continue development). Effect of temperature on starvation threshold varied significantly with larval age and food species. The URH declined with larval age at 5 °C, but not at 15 and 25 °C. The URH and grazing rates were high for early instars fed on C. calcitrans, and for advanced instars fed on S. costatum. Carbon gain through feeding was maximum for 2-day-old larvae when fed with C. calcitrans and decreased with larval age. However, when fed with S. costatum carbon gain increased with larval age. This confirms that with development the utility of food types changes. The differences in the carbon gain can be attributed to differences in grazing rate due to variations in the size of the diatom cells, larval intersetular distance, diatom sinking rate and the photo-taxic behavior of larvae. Molting was observed at times when larvae were undergoing starvation and this could be viewed as stress-induced molting, and it differed with the larval age and food organisms. [Copyright &y& Elsevier]

Experiments were carried out to evaluate the influence of rearing temperature and food concentration (20 and 30 °C, 1×105 and 2×105 cells ml−1) on the starvation threshold and nucleic acid content of the larvae of Balanus amphitrite. The larvae were also field-reared using micro-enclosures. Laboratory-reared larvae were larger in size than the field-reared larvae. An increase in size, DNA content and instar index of the starved II instar larvae was observed indicating that the absence of food may not be fatal to this early instar. The temperature at which larvae were raised and the food concentration had variable influence on the capacity to withstand starvation. Exposure to increased temperatures during starvation eliminated the effect of doubling food concentration during their feeding period prior to starvation. The larvae reared at 20 °C had comparatively lower nucleic acid content. The laboratory-reared larvae had ca. 1.7 times greater RNA:DNA ratio than larvae raised at comparable temperature in the field. [Copyright &y& Elsevier]

Abstract: Barnacles have drawn the attention of many naturalists and often dominate fouling communities. Balanus amphitrite, is a shallow water acorn barnacle capable of inhabiting expanses from supralittoral to subtidal levels, and as an epibiont. Its potential to survive and successfully establish local population is endorsed by various physiological adaptations and larval sensory perceptions. The larval life cycle of this species has both planktrotrophic naupliar and non-feeding cyprid stages. The naupliar energetics has a bearing on the capabilities of cypris larvae to explore surfaces for settlement and also the recruitment success of juveniles. The most complete nervous system in the barnacles is established in the cypris larva. Although there has been considerable research with reference to their settlement and metamorphosis, not much is known about the olfactory, photo and auditory sensory mechanisms with respect to settlement and metamorphosis, which need further attention. Understanding the response of most sensitive life stages of barnacles to environmental changes in intertidal habitats can also serve as important models for understanding the effect of climate change on species distribution. [ABSTRACT FROM AUTHOR]