Thraustochytrid fungoid protists in faecal pellets of the tunicate Pegea confoederata, their tolerance to deep-sea conditions and implication in degradation processes

S Raghukumar, C Raghukumar
1999 Marine Ecology Progress Series  
Dunng a swarm of the tunicate Pegea confoederala (salp) in the northern Arabian Sea, we examined their faecal pellets for thraustochytrid protists and bacteria to understand the role of the former in decomposition processes in the sea. Fresh faecal pellets from surface waters contained on average 6.58 X 106 thraustochytrids g-' dry wt, while bacterial numbers \.vere about 3 orders of magnitude higher. Highest numbers of thraustochytnds were observed when the faecal pellets were incubated at
more » ... for 6 d using unsterilized surface sea water, as cornpared to 10°C using sterilized or unsterilized water collected frorn 100 rn depth. Our results indicate that thraustochytrids in the water column may further colonize faecal pellets A thraustochytrid isolate cultured frorn such faecal pellets grew on pine pollen, Arternja larvae and nutrient broth, when subjected to 10°C and a pressure of 10 MPa, corresponding to 1000 m depth I t also produced proteases when subjected to combinations of 2 pressures, 0.1 (1 atm) and 10 MPa (100 atm], and 2 temperature conditions, 30 and 10°C. The results suggest that thraustochytnds found in such particulate organic matter may actively contnbute to decornposition processes not only in the surface waters, but also under deep-sea conditions.
doi:10.3354/meps190133 fatcat:2nxm2qkswneflkjtfpui47cdea