2.4 Microflora of Detritus of Peri phy tonic Fouling 



Detritus is formed as a result of the destruction of the remains of 

 dead organisms and the excrement of microflora and protozoa. During the 

 course of this processing in organic aggregates, which make up the mass 

 of detritus, a unique type of microcommunity is formed, consisting 

 mostly of bacteria, infusoria and heterotrophic fl age! lata, as well as 

 algae (primarily diatoms), and even small Crustacea (Rodina, 1963; 

 Fenchel , 1970). They determine the food value of the detritus, which 

 serves as one of the main sources of nutrition of planktonic and benthic 

 filter feeders, particularly in the highly productive areas of the shelf 

 and in the water beneath the eutrophic zone (Odum, de la Cruz, 1963). 

 In "young" detritus particles, the source of energy for bacterial 

 biosynthesis is the substance of the dead remains itself, while in 

 "mature" detritus particles, it is the dissolved organic matter of the 

 sea water (Finenko, Zaika, 1970; Khaylov, 1971). As a result of 

 bacterial biosynthesis utilizing this external organic matter, the mass 

 of organic matter in the detritus may increase as it matures, as is 

 observed, for example, in the feces of shrimp, which was held for 

 several days in sea water (Johannes, Satomi, 1966). 



The total population of bacteria in the detritus and detrital 

 sediments reaches magnitudes comparable to those of the active silt in 

 sewage plants: 5-25«10 cl/ml. The mass of bacteria represents as much 

 as 4% of the total organic matter of the detritus (Rodina, 1963; 

 Fenchel, 1970, 1972; Sorokin, 1971b; DiSalvo, 1973). The intensity of 

 the metabolism of detritus (20 mg 02/g'day) is close to that of the 

 benthic animals of the same weight. Thus, detritus must not be 

 considered dead organic matter: actually, it is an active component of 

 the ecosystem. It is the living fraction of the detritus which is 

 assimilated as it is consumed by filter feeders and sestonophages 

 (Newell, 1965; Sorokin, 1971b, 1972; Hargrave, 1971; Fenchel, 1972; 

 Odum, 1975). 



The porous surfaces of rocks, dead corals, clastic material, and 

 particles of large-grained benthic sediment are abundantly overgrown 

 with periphytonic microflora (Khaylov, Gorbenko, 1967; Sorokin, 1971b, 

 1973d). The biomass of bacteria in the periphyton on dead coral is 2-5 

 mg/g of scrapings. A significant portion consists of filamentous forms 

 of flexi bacteria such as Cladotrix , Crenotrix , or Leucotrix . The latter 

 frequently cover the surface of dead corals and the periphytonic algae 

 growing on it in a solid layer. Bacterial foulings on dead corals, 

 fragments, and large-grained sediment in coral reefs is one of the most 

 metabolically active components of the ecosystem and the primary 

 nutrient component of periphyton, consumed by many benthic animals. 



2.5 Biogeochemical Activity of Marine Microflora 



In aerobic marine basins, the basic biogeochemical functions of the 

 microflora is the oxidation of organic matter and the creation, by means 

 of the energy liberated in this process, of their own biomass. The 

 processes of biochemical consumption of oxygen and formation of CO2, 

 regulating the content of oxygen, pH and Eh of sea water and sediments 

 are related to these large-scale biogeochemical processes performed by 



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