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Microbial Degradation of Spilled Oil in Aqueous Environments: Beyond C15 Hydrocarbons
Published in Wael Ahmed Ismail, Jonathan Van Hamme, Hydrocarbon Biotechnology, 2023
Fernanda Lopes Motta, Nayereh Saborimanesh, Heather D. Dettman
The role of marine snow on the fate of spilled oil in the deep sea has attracted significant attention. Marine snow aggregates form and degrade in the water column. Marine snow forms naturally in the ocean and consists of living and non-living particles, involving mucus-producing phytoplankton and bacteria, detritus, feces from zooplankton and fish, and inorganic particles (Henry et al., 2018). Degradation is to a large extent due to the activity of attached microbes (Smith et al., 1992), which typically occur in aggregates in abundances that are orders of magnitude higher than in the ambient water (Alldredge and Silver, 1988; Kiørboe, 2000; Simon et al., 2002). Dissolved organic matter liberated from snow particles due to the activity of attached bacteria may become important substrates even for free-living (non-symbi-otic) bacteria (Kiørboe, 2000). Thus, marine snow aggregates are unique microcosms in the water column within which material and energy flows are regulated by complex biological and physical processes (Simon et al., 2002). Grossart et al. (2007) observed that cultures of bacteria isolated from marine snow showed a 20-fold increase in enzyme activity within 2 h of particle attachment (Grossart et al., 2007). Elevated extracellular enzymatic activity on aggregates may result from bacterial quorum sensing that has been demonstrated to occur in bacterial strains isolated from marine snow (Jatt et al., 2015).
Animals and Microplastics
Published in Judith S. Weis, Francesca De Falco, Mariacristina Cocca, Polluting Textiles, 2022
Jennifer F. Provencher, Sarah Y. Au, Dorothy Horn, Mark L. Mallory, Tony R. Walker, Joshua Kurek, Lisa M. Erdle, Judith S. Weis, Amy Lusher
Marine snow is recognized as particles (> 0.5 mm) or aggregations of particles, both organic and inorganic, which can be observed sinking through the water column. When MPs are associated with sinking material, such as bacteria, phytoplankton, microzooplankton, or within fecal pellets and bio-deposits (Cole et al., 2016; Piarulli and Airoldi, 2020), feeding structures (larvacean houses; Katija et al., 2017) and detritus, this can facilitate the transport of microplastics in the global ocean. Laboratory experiments have shown that marine snows can transport MPs (of different morphologies and polymer types) through the water column from surface waters and enhance their bioavailability to benthic organisms (Porter et al., 2018).
Particulate and Dissolved Organic Matter as Food
Published in Roger S. Wotton, The Biology of Particles in Aquatic Systems, 2020
A feature of oceanic surface waters is the presence of aggregates, a major type containing phytoplankton, blue-green algae, bacteria, protozoans, and mucus375–377 being referred to as marine snow. The composition of aggregates changes with phytoplankton abundance, and marine snow (with aggregates up to 20 cm in diameter) is found when there is a high concentration of phytoplankton, and when there is a low level of turbulence within the water378,379 (marine snow is discussed in Chapter 4). Mucus produced from diatom blooms, in addition to promoting the formation of marine snow aggregates, can accumulate at the sea surface where the inclusion of bubbles maintains the position of yellowish sheets covering wide areas.380 These can severely restrict light penetration, but only occur close to riverine inputs of nutrients that act as an algal fertilizer.
Influences and impacts of biofouling in SWRO desalination plants
Published in Critical Reviews in Environmental Science and Technology, 2021
Tamar Jamieson, Sophie C. Leterme
Those aggregates formed by microorganisms in the pelagic realm are commonly called marine snow. Marine snow is regarded as aggregates, of 0.5 mm or larger in diameter, which are highly diverse in origin, morphology, and characteristics within marine environments (Alldredge & Silver, 1988; Burd & Jackson, 2009; Silver et al., 1998; Simon et al., 2002). The structural components of aggregates therefore vary from fragile, porous, loosely associated smaller particles and organisms to those that are extremely cohesive, robust, and gelatinous in structure (Alldredge & Silver, 1988). Marine snow is primarily formed from algae, inorganic particles, zooplankton feeding structures, fecal pellets and detritus (Alldredge & Gotschalk, 1990; Alldredge et al., 1998). The formation of marine snow via physical aggregation is enhanced through two biological-mediated pathways (Alldredge & Silver, 1988). First, via the production of sticky mucus, exopolymers or products of cell lysis which increase the probability of colliding particles attaching, and also through the probability for potential collision resulting from biological alteration of the size and surface characteristics of the particles (Alldredge & Silver, 1988). Marine snow can be seen as macromolecular structures containing bacterial biofilms associated with the suspended particles (Gupta et al., 2016). They frequently contain higher concentrations of organic and inorganic particles than that of the surrounding environment (Prgzelin & Alldredge, 1983; Shanks & Trent, 1979), often resulting in heavy colonization by heterotrophic bacteria (Alldredge & Youngbluth, 1985; Alldredge et al., 1986). Polysaccharides, excreted by bacteria, produce a sticky medium consisting of gel like particles, which provides further structure to the aggregates together with the colloids and organic gels and organic matter (Alldredge et al., 1993; Long & Azam, 2001). Living and lysed cells in the majority of natural environments excrete extracellular polymeric material (Passow, 2002). Dissolved organic matter is removed from the surrounding environment by attached bacteria and converted to particulate matter through extracellular excretion (Alldredge & Silver, 1988).
The current state of knowledge for toxicity of corexit EC9500A dispersant: a review
Published in Critical Reviews in Environmental Science and Technology, 2019
Kevin M. Stroski, Gregg Tomy, Vince Palace
Plankton appear to be the most sensitive species toward Corexit EC9500A with many species displaying toxic effect concentrations below 1 ppm (Table 1) (Almeda et al., 2014; van Eenennaam et al., 2016). Significant growth inhibition was seen for six different marine microzooplankton species (Strombidium sp, Spirostrombidium sp, Eutintinnus pectinis, Favella ehrenbergii, Gyrodinium spirale, and Protoperidinium divergens) with EC50 values from 0.03 ppm to 0.76 ppm (48h) indicating a highly toxic response of these species to low levels of Corexit (Almeda et al., 2014). These effects may have serious impacts on marine food webs as many organisms, including some commercially viable fish, feed on such zooplankton in their larval stages (Beyer et al., 2016). Two phytoplankton species, Dunaliella tertiolecta and Phaeodactylum tricornutum, also showed effects at low Corexit concentrations (0.5 ppm, 3d) but in this case, was related to the formation of extracellular polymeric substances. These substances are naturally occurring excretions of many microorganisms, however, in extreme conditions they can aggregate together to form marine snow which can settle to the ocean floor causing major changes in sediment redox conditions and oxygen concentrations as they decay. This can result in harm to benthic organisms and was observed during the DWH spill where large concentrations of oil reached the sea floor through this method (van Eenennaam et al., 2016). In another study, phytoplankton communities containing 28 different species were exposed to Corexit 9500 in microcosm experiments. While growth inhibition was only experienced after relatively high exposures (63 ppm, 10d) at lower concentrations the species percentages in the community changed. Centric diatoms showed reductions from 63 to 15% after only 3 days, while both pennate diatoms (26 to 43%) and dinoflagellates (6 to 40%) saw increases to their abundance over this time (Ozhan & Bargu, 2014). These results suggest that changes to communities independent of mortality can occur even below the effect concentration. Based on the high toxicity of Corexit EC9500A to the many different plankton species (i.e. less than 1 ppm) and the propensity for effects even below these levels, we would recommend further studies investigate these effects in the field to better evaluate if plankton communities are truly affected as suggested here including chronic work to see whether they can restore themselves to pre-spill counts after dosage.