Invited Talk

Granular biofilms: their generation and application in environmental biotechnology
Venugopalan VP^*, YV Nancharaiah
Biofouling and Biofilm Processes Section, Water and Steam Chemistry Division, BARC Facilities, Kalpakkam, Tamil Nadu, India
^*Email: vpv@igcar.gov.in

In natural environments, microorganisms predominantly exist as members of complex communities, often as surface-associated consortia. Living in a community facilitates enhanced metabolic cooperation and genetic exchange among the bacteria. This mode of biofilm growth empowers the bacteria with enhanced tolerance to abrupt environmental changes, stressors and toxicants. Biofilms are at the core of the emerging interdisciplinary research area collectively known as “environmental biotechnology”. Environmental biotechnology has been defined as “managing microbial communities to provide services to society” (Rittmann 2006). Biofilms involved in such useful applications are broadly classified into 1) communities that detoxify contaminated water, soil and sediment and 2) communities capable of generating usable energy in the form of methane, hydrogen or electricity. It has been established that the beneficial functions in all these processes are performed by bacterial communities existing in the form of biofilms. Formation of biofilms under natural and/or engineered conditions involves self-immobilization of microbes with the help of an attachment substratum. Using engineered systems, microorganisms can also be self-immobilized into dense macro-scale granules (granular biofilms), without providing any carrier material or attachment substratum. Such microbial granules, consisting of mixed culture microorganisms, find application in liquid waste treatment because of their ability to quickly sink, facilitating easy liquid-biomass separation. Moreover, granular biofilm reactor technology allows designing of compact and high rate bioreactors. It is expected that future wastewater treatment plants will increasingly use granular biofilm based systems in place of the existing activated sludge process. This presentation will cover generation of granular biofilms using sequencing batch reactors, highlighting advantages of granular biofilms and possible mechanisms involved in their development. Specific examples of possible applications of granular biofilms in environmental biotechnology (biodegradation and biosorption) are illustrated.

Keywords: biofilms, bacteria, environmental biotechnology, granular biofilms

Biofouling on marine sensors and its prevention by ultraviolet radiation (UVR-C)
Patil JS¹^*, Toshiro Saino²,³
¹National Institute of Oceanography, Dona Paula, Goa 403-004, India,
²Hydrospheric Atmospheric Research Center, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan,
³Japan Science and Technology Agency, Kawaguchi, Japan
^*Email: patilj@nio.org

Biofouling of sensors is one of the most serious problems hindering their long-term operations, especially in coastal environments. To facilitate the long-term monitoring of oceanic processes using remotely operated system, it is necessary that the sensors remain foul free during deployments. In order to develop an efficient monitoring system, it is not only important to keep the sensors clean but also to understand the nature of effect on the operation of marine sensors. An overview of these issues will be addressed in the presentation. The results obtained from the practical application of ultraviolet radiation (UV-C; 254 nm) in preventing biofouling from the optical windows of fast repetition rate fluorometer (FRRF) will be presented. The presentation further highlights the importance of design of the optical windows for fluorometers such as FRRF in minimizing interference from the biofilm algal fluorescence during measurements.

Keywords: Biofouling, Sensors, Ultraviolet radiation

Spatio-temporal variations in demersal fish community structure along the fishing grounds of Goa, Central West coast of India
Rivonker CU¹^*, VP Padate¹, SS Sawant², K Venkat², AC Anil²
¹Department of Marine Sciences, Goa University, Taleigao Plateau, Goa, India,
²National Institute of Oceanography, Dona Paula, Goa, India
^*Email: curivonker@gmail.com

Coastal, estuarine and bay waters of Goa, along the Central West coast of India, in the near vicinity of the Mormugao Port Trust, support diverse demersal fish fauna as evidenced from the observations made in the present study. The present study updates the baseline information of the demersal fish community structure in the light of the anthropogenic input in the port region. Data collected in the present study from 41 trawl hauls have been analysed to elucidate aspects such as taxa composition and seasonal variability among the total community. In the present study, a total of 137 taxa comprised of  finfish, crustaceans, molluscs and other miscellaneous groups were observed, of which 91 were  regularly occurring, whereas, 46 were rarely occurring. Observations made in the present study reveal that the number of taxa among teleosts (99) was higher than crustaceans (20) however percentage contribution to the total catch displayed an inverse trend among these two groups. In addition to these taxa, other miscellaneous taxa (18) contributed in meagre quantities to the total catch. Among the species reported in the present study, Caesio cuning is being reported for the first time from the West Coast of India, and 13 species are being reported for the first time from Goa coast. The results obtained on the seasonal variations among major demersal, minor demersal and pelagic faunal groups are presented and discussed with respect to habitat variability. 

Keywords: Demersal fish, Seasonal variations, Species diversity, Community structure, Goa, Central west coast of India

Competitive strategies within a fouling diatom community
Mitbavkar S^*, AC Anil
National Institute of Oceanography, Goa, India
^*Email: mitbavkars@nio.org

Natural diatom biofilms were studied under controlled conditions to understand the roles of nutrients, initial cell inoculum and seasonal variation in species composition in structuring the fouling diatom community. Seasonal variations were observed in the diatom species interactions during the monsoon, post-monsoon and pre-monsoon periods depending on the species composition. In the monsoon community, high densities achieved by the opportunistic species, Nitzschia longissima in nutrient enriched (NE) condition probably denied access to key nutrients to its competitors, thereby resulting in competitive exclusion. However, in unenriched (UE) condition the same species could not prosper, even though its initial field inoculum was high, probably because of its higher half-saturation constant for nutrients thereby resulting in co-existence of many species. In the post-monsoon community, NE favored the species with comparatively higher growth rate, Amphora coffeaeformis thereby suppressing the growth of other co-existing species whereas UE resulted in similar growth rates of the initial dominant species. This competitive trait was found to be effective at an appropriate cell density ratio of the competitive and target species. In the pre-monsoon community, nutrients did not play an important role for Navicula transitans var. derasa f. delicatula and Amphora turgida in contrast to A. coffeaeformis and Amphora hyalina because of their lower initial inoculum. In these experiments, as the community was developing, certain species were dislodged from the substrata and hence removed from the environment. In another experiment, where all the species stayed in the community throughout, it was observed that the larger sized species which are known to be the ‘storage specialists’ that can store the nutrients for use during the low nutrient conditions, dominated the community ultimately. This shows that, not only the strategies employed by the species but also the environmental conditions play a role in deciding the fate of the community. Understanding such pathways within the biofouling community will be useful for modeling the interactions between diatom species in various habitats under different resource conditions.

Keywords: Fouling diatom community, Initial cell inoculum, Species composition, Competitive exclusion, Co-existence, Storage specialists

Distribution and effects of the key invasive species in the northern Baltic Sea
Helen Orav-Kotta^*, Jonne Kotta, Kristjan Herkül
Estonian Marine Institute, University of Tartu, Mäealuse 10a, Tallinn 12618, Estonia
^*Email: helenorav@sea.ee

In recent years at least one successful invasion has been recorded annually at the coastal range of the northern Baltic Sea. Providing very low biological and functional diversity of these coastal ecosystems such high invasion rate undoubtedly destabilizes the integrity of our ecosystems. The polychaete Marenzelleria neglecta, the bivalve Dreissena polymorpha and the amphipod Gammarus tigrinus are ranked among the most influential exotics in the Baltic Sea. The species are potentially able to affect biodiversity and modify organic matter and energy transfer pathways compared to the pre-invasion time. In this paper distribution and ecological impacts of these three keystone species are described in the northern Baltic Sea. M. neglecta prevails in eutrophicated soft bottom habitats where the species may reduce the growth and survival of native polychaetes and amphipods. D. polymorpha is able to colonize both fresh and brackish water bodies as well as soft or hard sediments. Prior to this invasion there was no benthic suspension feeding mode in the northern Baltic Sea where salinity is below 5 psu. Thus, D. polymorpha potentially increased the energy flow from pelagic system to benthos and caused a shift from pelagic production to benthic production. This was also supported by experimental observations about the fertilizing effect of the bivalve on macrophyte and associated invertebrate communities. The effects of D. polymorpha were more pronounced in fresh than in brackish water environments. G. tigrinus is currently the most aggressive nonindigenous species in the region. Since the late 1990s and 2000s G. tigrinus significantly expanded its distribution in the Baltic Sea and currently threatens the integrity of mesoherbivore assemblages in the area. The studied abiotic environmental variables did not explain the spatial variability of M. neglecta, D. polymorpha and G. tigrinus indicating that the species are still at their initial phase of invasion.

Keywords: Baltic Sea, Dreissena polymorpha, Gammarus tigrinus, Marenzelleria neglecta, Diversity.