Annual Community Respiration Research Articles

Benthic primary production during emersion: In situ measurements and potential primary production in the Seine Estuary (English Channel, France)

A two year survey of benthic primary production during periods of emersion was performed on two stations of an intertidal mudflat (a muddy-sand station and a muddy station) in the Seine Estuary (English Channel, France). The goals of this study were to investigate the seasonal variations of metabolism, to estimate daily potential primary production variation at the annual scale and to estimate the annual potential primary production of the mudflat. Primary production and respiration were estimated by in situ measurements of carbon dioxide fluxes. Chlorophyll a concentration exhibited a great variability on both locations. Gross community production ranged from ca. 0 to 77 mg C m −2 h −1 at the muddy-sand location and from ca. 0 to 122 mg C m −2 h −1 at the muddy location. Community respiration showed a seasonal trend following temperature variations (up to 28.51 mg C m −2 h −1 in the muddy-sand and up to 23.40 mg C m −2 h −1 in the mud). Daily potential primary production was calculated, according to seasonal variations of photosynthetic parameters calculated using three photosynthesis versus irradiance curves obtained for the muddy location. The annual gross community primary production was 135 g C m −2 yr −1, leading to a low autotrophic annual budget, considering an annual community respiration of 110 g C m −2 yr −1.

In situ measurements of benthic primary production during emersion: seasonal variations and annual production in the Bay of Somme (eastern English Channel, France)

A survey of benthic primary production during periods of emersion was performed in a muddy-sand station of the Bay of Somme. Primary production and respiration were estimated by in situ measurements of carbon dioxide fluxes using infra-red analysis. Photosynthetic response of the community to incident light and temperature was analysed at different periods of the year. Seasonal variations of the photosynthetic parameters were estimated using the photosynthesis versus irradiance (P–I) curves constructed in February, April, July, August and October. The rate of maximum gross community primary production (Pm), highly correlated to sediment chlorophyll a (Chl a) content, was low in February (6.7mg Cm−2h−1) and high in July (97.7mg Cm−2h−1). Photosynthetic efficiency at low light intensity (α) was positively correlated to Pm. The very high production (Pm=126.8mg Cm−2h−1) and productivity (ratio of Pm and sediment Chl a content) measured in March may be related to the set down of active planktonic microalgae. At five dates, the effects of temperature on primary production seemed to overshadow the role of light. The Q10 for primary production varied from 1.2 in August to 3.0 in December. Daily potential primary production was calculated as a function of theoretical and measured irradiance for the period of superimposition of day and emersion. At the annual scale, the potential gross community primary production was 147g Cm−2 with theoretical irradiance and 110g Cm−2 with measured irradiances. The annual community respiration was 188g Cm−2, leading to a heterotrophic annual budget. The annual pattern of daily production can be largely explained by changes in day length. It is also characterized by a fortnightly variability due to the variation of the total daily irradiance available for photosynthesis caused by the superimposition of the tidal and day/night cycles. Finally, sharp variations occurring with nebulosity can overshadow this fortnightly variability.

Ecological evaluation of the Cumberland Basin ecosystem model

A holistic ecosystem simulation model has been developed for the Cumberland Basin and upper Chignecto Bay, a turbid macrotidal estuary at the head of the Bay of Fundy. This one-dimensional deterministic model has three compartments, three boundaries and three interacting submodels (physical, pelagic and benthic). Twenty-eight biological state variables represent broad functional groups of organisms and non-living organic carbon pools. All major components of the estuarine ecosystem are included. At the present stage of development, individual pelagic state variables give reasonable annual simulations which are in general agreement with available calibration data. Major problems remain with some benthic state variables, especially the subtidal ones about which little is known. In aggregate, the model performs well and output at the ecosystem level agrees with field observations. In the Cumberland Basin water column, annual community respiration exceeds phytoplankton net production (1–3 g C m −3) by a factor of 2–5 suggesting the importance of carbon imported from surrounding saltmarshes and the seaward boundary. Annual community respiration and microalgal net production (28 g C m −2) on the other hand are closely balanced in intertidal sediments. Respiration in subtidal sediments is entirely dependent upon sedimented carbon. The model supports the hypothesis that the Cumberland Basin is a heterotrophic ecosystem with low primary production which requires imported organic carbon to support the production and respiration of higher trophic levels.

A preliminary organic carbon budget for a small dystrophic lake in Maritime Canada

The results of a preliminary organic budget for a small (1.13 h) dystrophic lake in Maritime Canada are presented. Wood's Pond is moderately autotrophically productive (395 mg C m-2 day-1). Allochthonous inputs overwhelmed autochthonous production by an approximate ratio of 9.7:1. Seepage through the surrounding Sphagnum mosses accounted for 89.9% of all organic carbon entering the lake while fluvial transport was responsible for over 90% of losses. The yearly balance was a net loss of approximately 1820 kg C. The marked dominance of allochthonous inputs over autochthonous production obviously influences the physico-chemical limnology of Wood's Pond but it does not necessarily follow that this system is heterotrophic. The yearly autotrophic production, approximately 1466 kg C, essentially balances an annual community respiration and insect emergence of 1481 kg C. This suggests that, at least in theory, the biological functioning of this dystrophic lake system could be driven almost entirely by autotrophic production.

Structure and Productivity of Grassland Small Mammal Communities Related to Grazing-Induced Changes in Vegetative Cover

Effect of grazing on the structure and productivity of small mammal communities in four types of North American grasslands is examined quantitatively using data collected during a 4-year period. Small mammal communities in tallgrass and montane grasslands appear more affected by grazing and the subsequent reduction in vegetative cover (=total above-ground standing crop of plants) than do small mammal communities in shortgrass and bunchgrass grasslands. This trend is evident when small mammals in grazed versus ungrazed habitats are compared with regard to mean community biomass, annual community respiration, production, and consumption, mean species diversity and evenness, proportional species and functional group composition, seasonal dynamics of community biomass, and temporal variation in proportional species composition. These results lend further support to the hypothesis that the general composition of grassland small mammal communities is determined primarily by structural attributes of the habitat.

Community metabolism of intertidal flats in the Ems-Dollard estuary

To obtain an insight into the flux of carbon through intertidal sediments of the Ems-Dollard estuary, the annual cycles of gross benthic primary production and community respiration were measured at six stations, together with a set of environmental parameters. In a stepwise multiple regression analysis it was shown that temperature alone and temperature plus viable bacteria explained 50 and 70% respectively of the observed variation in community respiration. Other variables, including the rate of primary production and amount of organic carbon in the sediment were less important. The rate of primary production could not be fitted adequately into a multiple regression equation. The annual values of community respiration (177–794 gO2·m-2·yr-1) and primary production (82–628 gO2·m-2·yr-1) were within the range of published values. except for one station in the vicinity of a wastewater outfall, which had an extreme production (average 984 gO2·m-2·yr-1). At four stations, annual community respiration exceeded primary production by 40%. It is concluded that the main carbon flux within the sediment, from CO2 to benthic primary producers, to benthic consumers and from there to CO2 again,was completed within a month or so, leaving untouched the large bulk of organic matter within the sediment. Possible effects of wastewater discharges on community metabolism are discussed.

The ecology of eelgrass, Zostera marina (L.), fish communities. II. Functional analysis

Consumption, production, and respiration of fish communities utilizing two eelgrass beds in a shallow estuarine system near Beaufort, North Carolina have been estimated for 1971–1972: annual production was 21.7 kcal/m 2 in each bed with pinfish accounting for 45 and 68% of the production in the Phillips Island and Bogue Sound beds, respectively. Annual community respiration was 57.9 and 69.7 kcal/m 2 in the two beds with pinfish accounting for 62.6 and 26.7% of the total in the Bogue Sound and Phillips Island beds, respectively. Estimation of the annual food energy consumed by the eelgrass fish community using the Winberg and daily ration methods gave values within 6% of each other. Energy turnover was high (2.8), and the efficiency of energy dissipation low for the two eelgrass fish communities, suggesting that the resident fish populations were adapted to the temperature extremes within the bed. High ecological efficiencies of 0.24 and 0.23 and the high overall efficiency of the eelgrass system (production/solar radiation) of 0.0051 and 0.0086% indicate that the eelgrass beds are efficient systems for converting consumed energy and solar radiation into fish.

Respiration of a Sublittoral Community

Respiration of a sublittoral community was examined off Sapelo Island, Georgia, from July 1969 through July 1970. Total community respiration ranged from 53.7 ml O_2 m(—2)hr(—1) in January to 92.7 ml O_2 m(—2)hr(—1) in July. A positive correlation was found between community respiration and water temperature. Annual community respiration was estimated to be 676.6 liters O_2 m(—2)yr(—1). The macrofauna consisted of 103 species representing ten phyla. Species abundance ranged from 744 individuals/m2 in July to 14,213 individuals/m2 in March. Biomass (ash free dry wt) increased from 7.3 g/m2 in October to 20.2 g/m2 in March. Macrofaunal respiration comprised from 5 to 26% of community respiration. Bacteria were the major functional component of the community accounting for 30% to 60% of the total respiration. Meiofaunal—microfaunal—microfloral respiration contributed from 25% to 58% to total community respiration. Sediment chemical oxidation was responsible for 2.8 ml O_2 m(—2)hr(—1) in January to 8.5 ml O_2 m(—2)hr(—1) in July of the total oxygen uptake.