Quantification of the energy required for the destruction of Balanus amphitrite larva by ultrasonic treatment

Ultrasonic treatment, a relatively less explored technology in water disinfection, was used to quantify the energy required for the destruction of larvae of barnacle Balanus amphitrite, which is a major marine fouling and a potential invasive organism. Since the power used and treatment time for disinfection are economically, and practically, the most important parameters, the energy required to pulverize the larvae into pieces ≤30 μm was determined as a function of the acoustic power density. The present investigation suggests that an ultrasonic system operating at 20 kHz and 0.0975 W/cm3 can effectively pulverize barnacle larvae having length (~440 μm) and breadth (~350 μm) within 45 seconds using 0.1 mJ/larva of pulverization energy. It was also observed that following pulverization of the larvae, the bacterial abundance increased and the rate of release of bacteria was dependent on power level and treatment time, which in turn decided the pulverization rate and hence the rate of release of bacteria

Phytoplankton and Bacterial Communities in South Harbour, Manila Bay, Philippines

In line with the ASEAN-India project “Extent of Transfer of Alien Invasive Organisms in South/Southeast Asia via Shipping”, phytoplankton and bacterial communities in the waters off South Harbour, Manila Bay were investigated. Sampling was done in July and August 2012 and in April and May 2013. A total of 67 phytoplankton species including 29 diatoms and 38 dinoflagellates were identified. Potentially toxic Pseudo-nitzschia spp. were among the diatoms found as well as dinoflagellates Alexandrium spp., and Gymnodinium spp. The diatom Skeletonema costatum appeared to be the dominant species in July and August 2012, whereas Chaetoceros spp. constituted over 85% of the total phytoplankton assemblage in April and May 2013. Mean bacterial abundance ranged from 9.53 x 102–3.18 x 105 cells/mL in July 2012. In addition, 93 bacterial isolates were  identified using 16S rDNA, several of which belonged to the following phyla: Actinobacteria, Bacteriodetes,  Firmicutes, and Proteobacteria; whereas, others were determined as uncultured bacterial clones. These results will serve as a valuable baseline for future studies on phytoplankton and bacterial community structure in Manila Bay

Effect of hydrodynamic cavitation on zooplankton: a tool for disinfection

Application of hydrodynamic cavitation for disinfection of water is gaining momentum, as it provides environmentally and economically sound options. In this effort, the effect of cavitating conditions created by differential pump valve opening and that created by flowing through a cavitating element (orifice plates) on the microbes (zooplankton in sea water) is described. The experimental results are compared with modelling of cavitating conditions that includes cavity dynamics, turbulence generated by individual oscillating cavity, cell wall strength and geometrical and operating parameters of cavitation device. Theoretical model for quantifying the cavitationally generated turbulent shear and extent of microbial disinfection has been developed. Experimental results indicated that cavitation and/or turbulent fluid shear dominantly originating from cavitation are effective tools for sea water disinfection as more than 80% of the zooplankton present in the sea water were killed. It was also observed that shock waves generated due to cavitation is not the sole cause for zooplankton disruption. A correct physical mechanism accounting fluid turbulence and shear, generated from stable oscillation of cavity, significantly contribute towards the disruption. Further refinement of the model presented will serve as a basis for higher degree of disinfection and provide a practical tool for sea water disinfection

Characterization of Bacteria in Ballast Water Using MALDI-TOF Mass Spectrometry

To evaluate a rapid and cost-effective method for monitoring bacteria in ballast water, several marine bacterial isolates were characterized by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). Since International Maritime Organization (IMO) regulations are concerned with the unintended transportation of pathogenic bacteria through ballast water, emphasis was placed on detecting species of Vibrio, enterococci and coliforms. Seawater samples collected from the North Sea were incubated in steel ballast tanks and the presence of potentially harmful species of Pseudomonas was also investigated. At the genus-level, the identification of thirty six isolates using MALDI-TOF MS produced similar results to those obtained by 16S rRNA gene sequencing. No pathogenic species were detected either by 16S rRNA gene analysis or by MALDI-TOF MS except for the opportunistically pathogenic bacterium Pseudomonas aeruginosa. In addition, in house software that calculated the correlation coefficient values (CCV) of the mass spectral raw data and their variation was developed and used to allow the rapid and efficient identification of marine bacteria in ballast water for the first time

An inter-site study of biofouling recruitment on static immersion panels in major ports of South East Asia and India

Limited knowledge of native marine biodiversity hinders effective biodiversity management to safeguard South and Southeast Asia’s marine coastal environment against the threat of invasive species transfer through shipping. In particular, sessile marine biofouling organisms in South East Asian ports are poorly known. Through the support of the ASEAN-India Cooperation Project on the Extent of Transfer of Alien Invasive Organisms in South/South East Asia Region by Shipping, a coordinated effort to examine diversity of biofouling organisms in major port areas in Southeast Asia and India was made using polyvinylchloride (PVC) panels as recruitment surfaces in a static immersion study for a period of 12 months. Not surprisingly, the study revealed that fouling patterns differed between ports possibly as a result of dissimilar hydrographic conditions. However, there were also underlying similarities that reflected a regional uniformity in the composition of fouling communities. At the same time, the alien Caribbean bivalve Mytilopsis sallei was detected in Manila Bay (Philippines), Songkhla Port (Thailand) and Singapore. This is a first simultaneous biofouling survey involving scientists and government stakeholders from India and ASEAN nations of Brunei Darussalam, Indonesia, Lao PDR, Malaysia, Myanmar, Singapore, Thailand, Philippines and Vietnam

Association of bacteria with marine invertebrates: implications for ballast water management

Bacteria associated with plankton are of importance in marine bioinvasions and the implementation of ship’s ballast water treatment technologies. In this study, epibiotic and endobiotic bacteria associated with zooplankton, including barnacle nauplii, veliger larvae, and adults of the copepod Oithona sp., were characterized and quantified. Barnacle nauplius and veliger larva harbored ~4.4 × 10⁵ cells ind⁻¹ whereas Oithona sp. had 8.8 × 10⁵ cells ind^-1. Computation of bacterial contribution based on biovolume indicated that despite being the smallest zooplankton tested, veliger larvae harbored the highest number of bacteria, while barnacle nauplii, the largest of the zooplankton, tested in terms of volume contributed the least. Pulverization of zooplankton led to an increase in bacterial numbers; for example, Vibrio cholerae, which was initially 3.5 × 10³, increased to 5.4 × 10⁵ CFU g^-1; Escherichia coli increased from 5.0 × 10² to 1.3 × 10⁴ CFU g^-1; and Streptococcus faecalis increased from 2.1 × 10² to 2.5 × 10⁵ CFU g^-1, respectively. Pulverized zooplankton was aged in the dark to assess the contribution of bacteria from decaying debris. Aging of pulverized zooplankton led to emergence of Chromobacterium violaceum, which is an opportunistic pathogen in animals and humans

Underwater adhesion: the barnacle way

Barnacle cement is an underwater adhesive insoluble protein complex. Marine proteins secreted by the invertebrates such as barnacles and mussels have potential application as powerful adhesives as they insolubilize and adhere to variety of substrates in aqueous environment. The adhesive properties of the barnacle adhesive proteins have been utilized for various dental and medical purposes. These polyphenolic proteins are currently in demand as they are non-toxic biomaterial, highly effective glues and it is very difficult to raise antibodies against these proteins and owing to this low immunogenicity is also attractive for human applications. This review provides a brief account of biochemical composition of barnacle adhesive proteins and their applications

Influence of elevated temperature and pCO₂ on the marine periphytic diatom Navicula distans and its associated organisms in culture

Influence of temperature and pCO₂, reflecting the future climatic scenario, on the marine periphytic diatom (Navicula distans) and its associated organisms was evaluated. Navicula distans along with its associated picoperiphyte and heterotrophic bacteria were exposed to two temperatures (30°C-present day, and 34°C-projected for year 2100) and pCO₂ levels (~500 µatm-present day, and ~1500 µatm-projected for year 2100) in a 2 × 2 factorial design. It was observed that rising temperature reduced the abundance of N. distans and picoperiphyte, but increased that of heterotrophic bacteria. On the other hand, rising pCO₂ favoured the growth of N. distans and picoperiphyte and had no significant effect on the bacterial growth. Synergistically, rising temperature and pCO₂ had a negative effect on N. distans, and a positive effect on picoperiphyte and heterotrophic bacteria. Additionally, this also resulted in the reduction of diatom cell size. This study suggests that in the future climatic scenario, increased abundance of picoperiphyte and heterotrophic bacteria along with smaller N. distans cells might influence the carbon budget and may have a cascading effect on higher trophic levels

Exploration and metamorphosis in Balanus amphitrite Darwin (Cirripedia; Thoracica) cyprids: significance of sugars and adult extract

Earlier observations have shown that sugars in solution adsorb electrostatically through –OH groups to polar groups associated with the cypris larva temporary adhesive (CTA). Lens culinaris agglutinin (LCA)-binding sugar chains of the adult extract (AE) have been suggested to be involved in the settlement of Balanus amphitrite. In the present study experiments were carried out to assess how cypris larvae would explore and metamorphose when treated with LCA-specific sugars (i.e. d-glucose and d-mannose). The influence of d-galactose was also assessed similarly. Evaluation of sugar-treated as well as nontreated cyprids was carried out with AE-coated and non-coated multiwells containing filtered sea water (FSW). d-mannose-treated cyprids resulted in higher metamorphosis than the nontreated cyprids at 10−8 M, whereas cyprids treated with the other LCA-specific sugar (d-glucose) showed an inhibitory effect in the absence of AE. This result implies the involvement of d-mannose moieties of AE in the settlement promotion of B. amphitrite. The barnacle cyprid, while exploring some surfaces, leaves behind ‘footprints’ of temporary adhesive. In the absence of AE, sugar-treated cyprids did not deposit footprints. Concurrently, the sugar-treated cyprids deposited footprints when exposed to multiwells coated with AE. A comparison of observations between single cyprid and multiple cyprid assays showed a similar trend, thus indicating that larva–larva interaction may not play an important role, when such pretreated larvae are subjected to assays. The third antennular segment with its attachment disc is the most obvious point of contact between the cyprid and the substratum during exploration. The detection of AE, even after blockage of polar groups of CTA on the third antennular segment, suggests availability of alternate sites for pheromone reception