Effects of gas and oil field structures and effluents on fouling community production and function

Abstract

From Conclusions and Significant Findings: “1) Production Platform 296B was estimated to have discharged 5.08 x 105 bbl of produced water during  1978-1979. 2) Results from respirometry experiments indicated that biofouling primary production rates were low and that produced water generally increased the oxygen demand of the systems under study, particularly the biofouling components. 3) A well casing on Production Platform 296B had lower biomass than other platform supports, measurable effects on total biomass from produced water were limited to near the area of the discharge point. 4) Pistol shrimp were significantly more abundant at 8-m depths that at 3-m depths during both summer and winter, and were slightly more abundant in summer than winter. 5) Stone crabs were significantly more abundant at 3-m depths than at 8 m and were more abundant in summer than in winter. 6) Brittle stars were patchily distributed and were most abundant at Satellite 288-5. Maximum densities were at 3-m depths. 7) Biomass of macroalgae was higher in summer  (28 g/m² at 3 m;  6 g/m² at  8 m) than in winter (6 g/m² at  3 m; 1.0 g/m2 at  8 m) and higher at 3-m depths than at 8-m depths. 8) The macroalgae were dominated  by greens and reds, distribution by species was patchy during both seasons and exhibited few definite trends. 9) During winter, structures without discharges had higher macroalgae biomass at 3-m depths than structures with discharges. 10) Recolonization samples taken for summer and fall seasons were dominated by Balanus amphitrite. Beneath the discharge, numbers and biomass increased with depth, whereas abundance and biomass decreased with depth at control structures. 11) Recolonization rates were low for winter and spring seasons. 12) Long-term recolonization experiments performed at the surface for summer to winter and winter to summer periods gave results similar to the short-term seasonal experiments. In general, lowest biomass was obtained at production platforms and highest biomass at control structures. 13) S. tintinnabulum condition was intermediate in summer, lowest in fall and increased from the fall low to a spring high. The differences were mostly associated with reproduction stages. 14) Barnacles at 1-m depths were characterized  by significantly better condition than those living at 8-m depths. 15) Comparisons of the production discharge leg to a quarters platform leg using condition of barnacles from 1-m deep collections as the response variable showed no significant differences. 16) A 10% solution of produced water-seawater killed 100% of the amphipod J. falcata in 48 h; a  1% solution killed  12.5% in 48 h. 17) The large barnacle, Balanus tintinnabulum, feeds during the night with feeding rates apparently higher in summer than in winter. 18) Barnacle production experiments indicated production rates for a single recruitment of B. amphitrite was  9.3 g/m²/d and that adult size is attained in 1 yr. 19) Production experiments using the hydroid, Tubularia crocea as a test animal, indicated that winter production rates for an average stalk was  0.00016 g/d for areas undergoing regrowth after clipping, and 0.00042 g/d for undamaged areas of the colony. 20) Based upon the above results and those from time-lapse photography, hydroid production is high during winter and the colonies decline markedly during spring. Production rate of the bryozoan Bugula neritina during a winter to spring period was estimated to have been 0.24 mg/cm²/d.”