| In situ measurements of primary production and respiration were performed using benthic chambers in an area of Ruditapes philippinarum communities and its adjacent field of Jiaozhou Bay, Qingdao, China. Sheldon-type and normalized biomass size spectra of metazoan benthos of eight cruises are made in the two stations and effects to the benthic ecological system function are discussed. Compared to the method of BCSPM (Benthic Chamber System for Production Measurement), secondary production and respiration of benthic assemblages are calculated by continuous integral model.It shows that environmental factors vary seasonally in the studied months in Jiaozhou Bay, which can be separated into two seasons: early summer (June) and summer, autumn (July and September). The Chl-a and Pha-a content are higher in early summer than summer and autumn, due to phytoplankton bloom. Sediment characters are important controlling factors of Chl-a and Pha-a content. Environmental conditions are similar in the two studied stations. A total of 18 meiofauna groups are identified. The most dominant group is nematode, accounting for 91.1% of the total abundance with benthic harpacticoid copepods in the second, accounting for 6.48%. The remaining groups included polychaeta, nauplii, bivalvia, and so on. The average meiofaunal abundance, biomass and production are 1975.14±382.61 ind.10cm-2, 1269.89±576.16μg dwt.10cm-2, 11429.03±5185.44μg dwt.10cm-2·a-1, respectively. A total of 71 species are identified in macrofauna assemblages, with 58 species in raft-cultural station and 50 species in outside station. The dominant species are Lumbrineris inflate and Ruditapes philippinarum in raft-cultural station, and Lumbrineris inflate, Sternaspis sculata, Nephtys oliogobranchia outside. The average macrofaunal abundance, biomass and production are2277.5±2294.28 ind.m-2 ,199.95±433.55g·m-2,105.76±228.30 g. m-2·a-1. Trawling disturbance has no significant effect on the meiofaunal abundance and the macrofaunal abundance of outside station, but significantly lowers the macrofaunal abundance in aquiculture station attributed to macrobenthic community difference. The benthic community is controlled by environmental variations combination of salinity, temperature, pH, Chl-a and silt-clay content.Low benthic primary production is measured in the investigation area by the method of BCSPM, due to low irradiance at the sea floor. Benthic respiration is 5.95±1.43 mmol·m-2·h-1 in the aquiculture station, which is higher than the value (1.65±0.22 mmol·m-2·h-1) in the outside station. It is because of the large number of Ruditapes philippinarum in the aquiculture station. Benthic respiration increases after trawling disturbance, possibly due to the increasing of microorganism. Nitrogen fluxes have the same changeable trend as respiration, and the results of nitrogen flux confirm the values of benthic primary production and respiration. The study shows that this benthic system is heterotrophic and strengthens the idea that an important pelagic-benthic coupling is required for the functioning in such coastal ecosystems.Sheldon biomass spectra appear biomodal, with obvious biomass trough in 3 to 6 size class. It is similar to most of the other studies. The average slope,intercept and regression coefficient of normalized biomass spectra in the two stations are 0.65 and -0.813, 14.22 and 15.16, 0.789 and 0.90 , respectively. The biomass spectra reflect that the ecosystem in aquiculture station is in an unstable condition. Artifical seedling leads to higher slope of the normalized biomass spectra in aquiculture station. Food competition theory can be used to explain the variation of intercept. Trawling disturbance significantly influences on parameters of the size spectra in aquiculture station with relatively lower effect in outside station. The reason is that the large size benthos are more sensitive to the disturbance.By the method of continuous integral model, secondary productions and respirations of macro- and meiofauna are calculated in the studied area. The values are 16.82±16.22g dwt·m-2·a-1and 0.96±0.95mmol·m-2·h-1, 4.33±2.38g dwt·m-2·a-1 and 0.20±0.11mmol·m-2·h-1 in the two stations respectively. Compared to the method following the formula P=9B, continuous integral model can provide more reliable evaluation in secondary production of meiofauna. However, the respiration values are lower, compared to BC. It is that BC can measure the total respiration of benthic community, but the biomass spectra can only provide the values among the studied size classes.
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