During composting, facilities usually exert greater control over the bio-oxidative phase of the process, which uses a specific technology and generally has a fixed duration. After this phase, the material is deposited to mature, with less monitoring during the maturation phase. While there has been considerable study of biological parameters during the thermophilic phase, there is less research on the stabilization and maturation phase. This study evaluates the effects of the type of starting material on the evolution of microbial dynamics during the maturation phase of composting. Three waste types were used: sludge from the fish processing industry, municipal sewage sludge and pig manure, each independently mixed with shredded pine wood as bulking agent. The composting system for each waste type comprised a static reactor with capacity of 600L for the bio-oxidative phase followed by stabilization and maturation phase in triplicate 200L boxes for 112days. Phospholipid fatty acids, enzyme activities and physico-chemical parameters were measured throughout the maturation phase. The evolution of the total microbial biomass, Gram + bacteria, Gram - bacteria, fungi and enzymatic activities (β-glucosidase, cellulase, protease, acid and alkaline phosphatase) depended significantly on the waste type (p<0.001). The predominant microbial community for each waste type remained present throughout the maturation process, indicating that the waste type determines the microorganisms that are able to develop at this stage. While fungi predominated during fish sludge maturation, manure and municipal sludge were characterized by a greater proportion of bacteria. Both the structure of the microbial community and enzymatic activities provided important information for monitoring the composting process. More attention should be paid to the maturation phase in order to optimize composting.

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The dominant fatty acids in all neutral lipid fractions of non-water hardened eggs from two wild and one cultured stock of striped bass Morone saxatilis were the monoenes, 18 : 1n9/ n7>16 : 1n7>17 : 1. The dominant fatty acids in the phospholipid fraction of all eggs, regardless of origin, were 22 : 6n3>18 : 1n9/n7>20 : 5n3>16 : 1n7>16 : 0>18 : 0. Arachadonic acid (AA, 20 : 4n6) was significantly lower (2·0%) in cultured fish eggs compared to either wild stock (5·8-6·1%). Fatty acids from the liver and eggs of wild Shubenacadie fish were similar to one another with respect to both neutral and phospholipid fractions. However, the AA and eicosapentaenoic acid (EPA, 20 : 5n3) content of the phospholipid fraction varied according to the hypothesized migration behaviour of Shubenacadie fish. The total lipid content of wild fish eggs was significantly greater than that of cultured fish. The total phospholipid content of Shubenacadie eggs was significantly higher than either Roanoke or cultured fish eggs. Phosphotidylinositol (PI) was the dominant phospholipid found in all egg samples from all origins as opposed to phosphotidylcholine, which is usually the dominant phospholipid. These data indicate that PI and AA may have important and as yet unidentified roles in fertilization and embryonic development in these fish. 1998 The Fisheries Society of the British Isles

Experiments were conducted to investigate larval mortality in cultured summer flounder during the first two weeks after hatch.The importance of feeding success,parentage, addition of algae, water quality, and the microbial community to mortality during this period were investigated. Larvae were raised in 2-L bowls at initial densities of 50 and 75/L with light aeration, 12L:12D photoperiod, and regular 1-L water changes.In all experiments mortalities were recorded and removed daily. In the first two experiments daily samples of larvae were taken to assess feeding success and to relate that to survival.The second experiment investigated the effects of both feeding success and the addition of algae to larval culture bowls on larval survival. The third experiment investigated the effects of water quality and bacterial load on survival during the experimental period. The first two experiments indicated that failure to establish .feeding is probably not the cause of catastrophic mortality of the larvae, although a statistical relationship existed between feeding incidence and survival in two of six cases. High variability (34 ± 38% n=82) in survival was seen in the first two experiments (both within and between parental crosses) suggesting that catastrophic mortalities were due to rearing conditions rather than gamete quality. The addition of algae to larval cultures increased survival from 13 ± 24% (n=33) during the ii ·f i rst experiment to 46 ± 39% (n=49 ) during the second experiment. The final experiment indicated that larval mortality was not linked to the measured microbial or water quality conditions. The relationship between the percentage of floating eggs at time of fertilization and survival at 10 DAH was found to be not significant, providing further evidence that gamete quality was not as important as rearing conditions in these experiments.iii ACKNOWLEDGMENTS

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