Net Daily Metabolism Research Articles

Development of a periphyton-based index for biological integrity for lakes and reservoirs in Baiyangdian Watershed, China

A periphyton-based index for biological integrity was developed to assess the ecological status of lakes and reservoirs in Baiyangdian Watershed, China. Periphyton and environmental surveys were conducted at 20 sites during 2009-2010. A total of 22 surveyed metrics of periphyton, which were classified into 6 categories: biomass groups, community structure, pigment ratios, bacteria diversity, enzyme activities, and metabolism were evaluated in order to understand their responsiveness to environmental degradation. Out of these 22 metrics, six metrics were selected to constitute the periphyton-based index for biological integrity: chlorophyll b, chlorophyll c: chlorophyll a ratio, alkaline phosphatase activity, bacteria dominance, net daily metabolism, and autotrophic index by sensitivity and redundancy analysis. Then the periphyton-based index for biological integrity was verified by an independent validation-site data set. The test results indicated the index could not only discriminate disturbed sites from reference sites, but also be triggered by land use types. The scores of periphyton-based index for biological integrity were significantly correlated with the environmental parameters, especially ammonia nitrogen and total phosphorus. These results suggest that this index may be a potential tool for assessing the ecological status of lakes and reservoirs, polluted mainly by organic contaminants in Baiyangdian Watershed.

The responses of epilithic algal community structure and function to light and nutrients and their linkages in subtropical rivers

Epilithic algal community structure and function are important indicators of stream ecosystem health and are sensitive to ambient environmental changes. In this study, we examined the impact of light and nutrients on epilithic algal community structure and function by an in situ nutrient addition and shaded canopy experiment in subtropical streams in China. Epilithic algae structure, dominated by diatoms, was significantly different with nutrient addition and light reduction. Nutrient addition increased the epilithic algae and diatom density, colonial life-forms, planktonic diatoms, and high-profile diatoms but decreased the low-profile diatoms. The shaded canopy increased the low-profile diatoms but decreased the adnate life-forms, planktonic diatoms, and high-profile diatoms. Epilithic metabolism, including gross primary production (GPP), net daily metabolism (NDM), and production/respiration (P/R) increased with nutrient addition, while respiration (R) only increased when the canopy was open with nutrient addition. Epilithic GPP had a significant positive correlation with diatom density (P < 0.01, R2 = 0.9425). Our results indicated that changes in epilithic algae structure due to changes in riparian canopy coverage and nutrients could affect epilithic algal community function. Quantifying the impacts of such drivers on community structure and function is vital to effective river management.

Serial discontinuity in naturally alternating forest and floodplain habitats of a Michigan (USA) stream based on physicochemistry, benthic metabolism, and organismal assemblages

ABSTRACTWe tested the response of several different water quality metrics at 6 sites along a 4-km alternating forest (canopied) and floodplain (non-canopied) reach of the East Branch of the Black River, an undisturbed northern Lower Michigan trout stream, during summer 2015. Physicochemical parameters were unchanged between sites and reflected an undisturbed continuum. In-stream woody debris was higher at the forest sites, whereas relative canopy cover and sunlight intensity were higher at the floodplain sites. Both benthic macroinvertebrates and adult caddisflies exhibited greater species richness and a higher abundance of shredders at the forest sites, and a higher abundance of scrapers at the floodplain sites. Fish specimen abundance, species richness, and percentage of trout were not different between sites, and instead all increased throughout the summer. Community respiration was unchanged between the single tested floodplain site and the forest sites upstream and downstream of it. Gross primary production and net daily metabolism were higher at the floodplain site, leading to stream autotrophy. This result was also obtained when tested in summer 2017. Our results support the idea that terrestrial habitat changes can singularly affect the fundamental ecological functioning of an undisturbed stream, primarily due to deviations in sunlight penetration and allochthonous input. Moreover, the short distances between sites with alternating results indicate the dynamic and serially discontinuous state of natural rivers.

Dissolved Oxygen Dynamics at the Sediment–Water Column Interface in an Urbanized Stream

This manuscript reports findings on sediment oxygen demand (SOD), gross primary production (GPP), net daily metabolism (NDM), and stream reaeration in an urbanized stream, the Jordan River, in Utah. The river has two segments; the Lower Jordan River, which is impaired for dissolved oxygen (DO) and the Upper Jordan River, which is fast flowing with coarse sediments and has no DO impairment. Summer SOD values for the Lower Jordan River ranged from a high 2.2 g DO/m2 per day to a low of 0.97 g DO/m2 per day with most of the sampled sites in the Lower Jordan River having SOD values greater than 1 g DO/m2 per day. SOD values correlated well with volatile solids in surface sediments of the Lower Jordan River. The Upper Jordan River showed SOD values as high as 3.0 g DO/m2 per day, which was attributed to hyporheic exchanges or groundwater upwelling. All sampled sites exhibited high SOD values in winter. A modified chamber method was employed to estimate community respiration (CR24), GPP, and NDM, while characterizing both the water column and benthos. In summer 2010, the sediment tray primary production (TPP) ranged from 1.0 to 7.4 g DO/m2 per day. In winter 2011, TPP ranged from 0.7 g DO/m2 per day to a high value of 5.6 g DO/m2 per day. NDM values indicated that the Upper Jordan River is a year round source of in-stream produced organic matter to the downstream Lower Jordan River with the majority of organic matter produced in the benthos. Reaeration measurements showed that the potential for reaeration is much higher in the mid-sections of the Jordan River, where the river has increased flow velocities due to topography, decreased depths, and a less uniform bottom.

Metabolic patch dynamics in small headwater streams: exploring spatial and temporal variability in benthic processes

Summary1. To gain a better understanding of the heterotrophic nature of small headwater streams in forested landscapes we explored the spatial and temporal variability of in‐stream organic matter processes. Three methods were used to measure the benthic metabolism of different in‐stream habitats in seven streams throughout a calendar year. This allowed us to analyse the contribution of various metabolic habitats (i.e. sediment, leaf litter, cobbles) to in‐stream metabolism during a natural flow regime. Furthermore, it allowed us to define in‐stream patchiness based on functional rather than structural elements.2. Bacterial growth, measured using a leucine assay, displayed a quadratic relationship over time with a peak in warmer months and consistently higher bacterial growth in fine depositional (3.00–710.64 mg C m−2 day−1) than coarse gravel (38.84–582.85 mg C m−2 day−1) sediments.3. Community metabolism, measured using dissolved oxygen chambers, showed distinct diel patterns and consistently greater net daily metabolism in leaf packs (−261.76 to −24.50 mg C m−2 day−1) than fine depositional sediments (−155.00 to −15.56 mg C m−2 day−1). Coarse gravel sediments (−49.55 to −16.88 mg C m−2 day−1) and cobble habitats (−151.98 to 55.38 mg C m−2 day−1) exhibited the lowest metabolic rates. Modelled whole‐stream metabolism was highly variable among streams and temporal patterns appeared driven by temperature and the relative contribution of patch configuration as a function of flow.4. Cellulose decomposition potential showed higher rates of microbial activity in fine depositional compared to coarse gravel sediments (30.5 and 29.1 kg average cotton tensile strength loss respectively), though there were higher rates of thread loss indicative of macroinvertebrate activity in gravel compared to depositional sediment (21% and 13% average thread loss respectively), with a slight quadratic trend. The high variability among habitats, streams and over time in this integrative measure may be explained by variability in local microbial activity as well as the potential for macroinvertebrates to contribute across patches.5. There were strong relationships among benthic processes and habitat structure, nutrient status, stream temperature and flow. Different habitats had distinct metabolic characteristics and these characteristics appear to influence stream food webs and biogeochemical cycling depending on the relative abundance of habitats. Generally, within habitat variability was less than among habitat variability and among stream variability was less than temporal variability. Hence, in terms of the spatial and temporal heterogeneity of benthic processes, these small headwater streams showed predictable metabolic patterns. However, there were few correlations between differing measures of benthic metabolism at the same patch and this suggests that caution should be taken when attempting to infer the rates of one level of metabolic activity (e.g. whole community metabolism) based on another (e.g. bacterial productivity).

Effects of dilution stress on the functioning of a saline Mediterranean stream

The effects of seasonality and dilution stress on the functioning of Rambla Salada, a hypersaline Mediterranean stream in SE Spain, were evaluated. The stream is subject to diffuse freshwater inputs from the drainage of intensively irrigated agriculture in the catchment and periodic losses of water through an irrigation channel. Metabolic rates and the biomass of primary producers and consumers were estimated over a 2-year period. During the first year several dilution events occurred, while during the second year the salinity recovery reached predisturbance levels. Functional indicators were compared in the disturbance and recovery salinity periods. Primary production and respiration rates in the Rambla Salada ranged between 0.07–21.05 and 0.19–17.39 g O2 m−2 day−1, respectively. The mean values for these variables were 7.35 and 5.48 g O2 m−2 day−1, respectively. Mean net daily metabolism rate was 1.87 ± 0.52 g O2 m−2 day−1 and mean production/respiration ratio was 2.48 ± 1.1, reflecting autotrophic metabolism. The metabolic rates showed the typical seasonal pattern of Mediterranean open canopy streams. Therefore, gross primary production (GPP) and ecosystem respiration (ER) registered maximum values in summer, intermediate values in spring and autumn and minimum values in winter. The metabolic rates and biomass of consumers were greater in the disturbance period than in the recovery period. However, they did not show significant differences between periods due to their important dependence on seasonal cycle. Seasonality accounted for much of the temporal variability in GPP and ER (76% and 83% in the multiregression models, respectively). Light availability seems to be the most important factor for GPP and ER in the Rambla Salada. Autotrophic biomass responded more to variations in discharge and conductivity than to seasonal variations. In fact, it was severely affected by freshwater inputs after which the epipelic biomass decreased significantly and Cladophora glomerata proliferated rapidly. Epipelic algal biomass was the most sensitive parameter to dilution disturbance.

Response of river metabolism to restoration of flow in the Kissimmee River, Florida, U.S.A.

Summary1. The single station diel oxygen curve method was used to determine the response of system metabolism to backfilling of a flood control canal and restoration of flow through the historic river channel of the Kissimmee River, a sub‐tropical, low gradient, blackwater river in central Florida, U.S.A. Gross primary productivity (GPP), community respiration (CR), the ratio of GPP/CR (P/R) and net daily metabolism (NDM) were estimated before and after canal backfilling and restoration of continuous flow through the river channel.2. Restoration of flow through the river channel significantly increased reaeration rates and mean dissolved oxygen (DO) concentrations from &lt;2 mg L−1 before restoration of flow to 4.70 mg L−1 after flow was restored.3. Annual GPP and CR rates were 0.43 g O2 m−2 day−1 and 1.61 g O2 m−2 day−1 respectively, before restoration of flow. After restoration of flow, annual GPP and CR rates increased to 3.95 O2 m−2 day−1 and 9.44 g O2 m−2 day−1 respectively.4. The ratio of P/R (mean of monthly values) increased from 0.29 during the prerestoration period to 0.51 after flow was restored, indicating an increase in autotrophic processes in the restored river channel. NDM values became more negative after flow was restored.5. After flow was restored, metabolism parameters were generally similar to those reported for other blackwater river systems in the southeast U.S.A. Postrestoration DO concentrations met target values derived from free flowing, minimally impacted reference streams.

An energy budget for the Kootenai River, Idaho (USA), with application for management of the Kootenai white sturgeon, Acipenser transmontanus

An energy budget provides a useful tool for examining the exchange of energy between trophic levels. In this study we examined the potential for autotrophic productivity and organic material to support higher trophic levels in three distinct geomorphic segments of the Kootenai River, USA. This approach is particularly important given that several species of fish, including the endangered Kootenai white sturgeon (Acipenser transmontanus), have been in decline since the installation of a large hydropower and flood control dam on the river. Previous research indicated that (i) the reservoir formed by Libby Dam was retaining significant quantities of nutrients and organic material and (ii) phosphorus was limiting periphyton accrual downstream from the reservoir. Thus food limitation was a likely mechanism contributing to the decline in fish populations. Net daily metabolism (NDM) was positive during only 30% of the growing seasons from 1993 to 1995 indicating that autochthonous production was rarely sufficient to support higher trophic levels. All reaches were generally exporting transported organic matter (TOM). Results of an energy budget indicated that macroinvertebrate standing crop was generally lower than that which could be sustained by the relatively short bursts of positive NDM. Estimated fish biomass was higher than that sustained by positive NDM or stored TOM at energetic conversion efficiencies (C.E.) of 10% at average and maximum estimated active metabolic rate. Autotrophic and detrital sources were generally insufficient to support the estimated fish biomass. This study combines detailed analyses of both the autotrophic and detrital energy pathways and thereby suggests a mechanistic explanation for the decline in fish abundance ultimately caused by impoundment.

Ecosystem metabolism in a Mediterranean shallow lake (Laguna de Santa Olalla, Doñana National Park, SW Spain)

Santa Olalla is a Mediterranean permanent coastal shallow lake, with high annual solar irradiation and warm water temperature throughout the year. Ecosystem metabolism, chlorophyll a concentrations, and physical and chemical features were studied in the Santa Olalla lake from March 1998 to February 2000. Gross primary productivity (GPP) and community respiration (CR) were determined using a modification of the one-station diel oxygen change method. Chlorophyll a, Secchi depth, and total phosphorous and nitrogen reveal Santa Olalla to be a hypereutrophic system. Values of GPP and CR were very high (average 7.88 g O2 m−2 d−1 and 8.52 g O2 m−2 d−1, respectively). Principal components analysis and a multiple regression model showed photosynthetically active radiation and soluble reactive phosphorus to be the main factors that control primary production in Santa Olalla. Also, the annual and interannual variation of water level in Santa Olalla seems to be an important factor that influences the ecological processes of this system. Mean net daily metabolism during a hydrologic period was not statistically different from 0 (0.008 g O2 m−2 d−1, p=0.99), and the average P/R ratio was not statistically different from 1 (1.164, p=0.343). These results suggest that the primary productivity was balanced with community respiration in Santa Olalla lake. The high values of metabolic rates and low nutrient concentrations in this aquatic ecosystem suggest a quick recycling of nutrients, which were assimilated almost instantaneously after mineralization.

Macrophytic, epipelic and epilithic primary production in a semiarid Mediterranean stream

Summary 1. Primary production by Chara vulgaris and by epipelic and epilithic algal assemblages was measured in a semiarid, Mediterranean stream (Chicamo stream, Murcia, Spain) during one annual cycle.2. The rates of gross primary production (GPP) and community respiration (CR) were determined for each algal assemblage using oxygen change in chambers. The net daily metabolism (NDM) and the GPPd−1 : CR24 ratio were estimated by patch‐weighting the assemblage‐level metabolism values.3. Gross primary production and CR showed significant differences between assemblages and dates. The highest rates were measured in summer and spring, while December was the only month when there were no significant differences in either parameters between assemblages. GPP was strongly correlated with respiration, but not with algal biomass.4. Chara vulgaris showed the highest mean annual metabolic rates (GPP = 2.80 ± 0.83 gC m−2 h−1, CR = 0.76 ± 0.29 gC m−2 h−1), followed by the epilithic assemblage (GPP = 1.97 ± 0.73 gC m−2 h−1, CR = 0.41 ± 0.12 gC m−2 h−1) and epipelic algae (GPP = 1.36 ± 0.22 gC m−2 h−1, CR = 0.39 ± 0.06 gC m−2 h−1).5. The epipelic assemblage dominated in terms of biomass (82%) and areal cover (88%), compared with the other primary producers. Epipelic algae contributed 84% of gross primary production and 86% of community respiration in the stream.6. Mean monthly air temperature was the best single predictor of macrophyte respiration and of epipelic GPP and CR. However, ammonium concentration was the best single predictor of C. vulgaris GPP, and suspended solid concentration of epilithon GPP and CR.7. Around 70% of the variation in both mean GPP and mean CR was explained by the mean monthly air temperature alone. A multiple regression model that included conductivity, PAR and nitrates in addition to mean monthly air temperature, explained 99.99% of the variation in mean CR.8. Throughout the year, NDM was positive (mean value 7.03 gC m−2 day−1), while the GPP : CR24 ratio was higher than 1, confirming the net autotrophy of the system.

The effects of elevated metals on benthic community metabolism in a rocky mountain stream

The effects of elevated metals (dissolved Zn, Mn and/or Fe) in a Rocky Mountain stream were assessed using measures of primary productivity, community respiration and water-column toxicity. Primary productivity was measured as rates of O 2 evolution from natural substrates incubated in situ in closed chambers. Oxygen depletion within these chambers, when incubated in the dark, provided estimates of periphyton community respiration. Sediment community respiration on fine-grained sediments, collected and composited along each stream study reach, was measured on-site by incubating these sediments in closed chambers and measuring O 2 depletion. Toxicity was measured as percent mortality of Ceriodaphnia dubia during 48 h acute tests. Gross (GPP) and net primary productivity (NPP) decreased significantly with increasing metal concentrations, from 10.88 ± 1.46 g O 2 m −2 day −1 to 0.83 ± 0.20 g O 2 m −2 day −1 and 9.85 ± 1.43 g O 2 m −2 day −1 to 0.81 ± 0.20 g O 2 m −2 day −1, respectively for the reference and most impacted site. Community respiration (CR) declined from 0.65 ± 0.08 g O 2 m −2 day −1 to 0.02 ± 0.01 g O 2 m −2 day −1 with increasing metal concentrations. Sediment community respiration (SCR) decreased from 0.26 ± 0.02 g O 2 m −2 day −1 to 0.01 ± 0.01 g O 2 m −2 day −1 at these same sites. Ceriodaphnia dubia mortality increased from 0% at the reference site to 95 ± 5% at the most impacted sites. Net daily metabolism, quantum yield and assimilation ratio all decreased with increasing metal concentrations, suggesting that both autotrophic and heterotrophic components of the periphyton community were impaired. Overall, functional measures were able to discern sites receiving greater metal impacts from less-impacted sites, with combinations of dissolved metals explaining between 25 and 92% of the variance in the regression models. Using these regression models we were able to calculate lethal and inhibition concentrations of dissolved Zn in the Eagle River. The lethal concentration (LC 50) of Zn for Ceriodaphnia dubia is 123 mg liter −1. The concentrations of Zn which inhibited respiration (IC 50) were 177 mg liter −1 for CR and 199 mg liter −1 for SCR. These results indicate functional measures may be as sensitive to metal concentrations as acute toxicity tests. Published by Elsevier Science Ltd

Effects of previous zinc exposure on pH tolerance of periphyton communities

AbstractThe community‐level effects of previous chemical exposure on resistance to a dissimilar subsequent stress were evaluated. Naturally derived periphytic communities on polyurethane‐foam artificial substrates provided colonists for development of new communities under controlled stress conditions in the laboratory. Communities were colonized under three levels of Zn stress: control, low (73 μg/L), and high (172 μg/L). After 21 d, laboratory‐colonized communities were exposed to 5 pH levels (control, 4.5, 4.0, 3.5, 3.0) for 48 h. No significant differences occurred between Zn treatments in response to pH for total biomass, assimilation ratio, respiration to biomass ratio, and net daily metabolism. Response to pH was dependent on Zn treatment for number of protozoan species, algal biomass, gross primary productivity, and community respiration. Number of protozoan species in high Zn was impaired in absence of pH stress. Primary production and community respiration were impaired in absence of pH stress in both low and high Zn. For these three end points, outcome for Zn treatments converged with increasing secondary stress; no differences between Zn treatment groups were observed at pH &lt; 4.0. For several end points, Zn‐stressed communities changed less, relative to their initial state, with subsequent acid shock.

EFFECTS OF PREVIOUS ZINC EXPOSURE ON pH TOLERANCE OF PERIPHYTON COMMUNITIES

The community-level effects of previous chemical exposure on resistance to a dissimilar subsequent stress were evaluated. Naturally derived periphytic communities on polyurethane-foam artificial substrates provided colonists for development of new communities under controlled stress conditions in the laboratory. Communities were colonized under three levels of Zn stress: control, low (73 μg/L), and high (172 μg/L). After 21 d, laboratory-colonized communities were exposed to 5 pH levels (control, 4.5, 4.0, 3.5, 3.0) for 48 h. No significant differences occurred between Zn treatments in response to pH for total biomass, assimilation ratio, respiration to biomass ratio, and net daily metabolism. Response to pH was dependent on Zn treatment for number of protozoan species, algal biomass, gross primary productivity, and community respiration. Number of protozoan species in high Zn was impaired in absence of pH stress. Primary production and community respiration were impaired in absence of pH stress in both low and high Zn. For these three end points, outcome for Zn treatments converged with increasing secondary stress; no differences between Zn treatment groups were observed at pH < 4.0. For several end points, Zn-stressed communities changed less, relative to their initial state, with subsequent acid shock.

The effects of nutrient enrichment on algae and macroinvertebrates in the everglades: A review

Over 400 metric tons of phosphorus and 12,000 metric tons of nitrogen flow annually into the northern part of the Everglades. Data describing the effects of nutrient enrichment, especially phosphorus, on algae and macroinvertebrates in the Everglades are reviewed and compared to our preliminary results. The Everglades is a harsh aquatic environment characterized by high summer temperatures (>35 C) and fluctuating, low oxygen conditions. In unenriched habitats, oxygen concentrations at the algae-water interface can vary from 200% supersaturation (approximately 30 mg/l) during the day to less than 3.0 mg/l at night. Although surface water carbon dioxide concentrations from nighttime respiration are depleted by noon of the following day, pH remains circumneutral because of high bicarbonate concentrations. Growths of cyanobacteria, often exceeding 6 cm in thickness, characterize unenriched open water habitats. Despite longstanding suggestions to the contrary, there is no evidence that the cyanobacterial mat is consumed by higher trophic levels. Annual net daily metabolism in unenriched habitats ranges from −0.065 to 2.01 g C m−2 d−1 with an average of 0.92 g C m−2 d−1. Previous reports concerning the effects of P enrichment on oxygen and macroinvertebrates are confounded by comparisons between habitats that differ with respect to hydroperiod, water depth, and macrophyte species composition in addition to nutrient loading. Nutrient enrichment causes disintegration of the abundant cyanobacterial mat and a shift in algal species composition and relative abundance. Annual primary production and algal biomass were 2.9 and 3.0× greater, respectively, in phosphorus enriched conditions compared to unenriched areas. Algal diversity, however, was not significantly different in enriched compared to unenriched habitats. Our preliminary analyses indicate that macroinvertebrate diversity and density are higher within enriched compared to unenriched areas if similar habitat types (submerged macrophyte beds) are sampled. Also, there is no evidence that “fish kills” caused by anaerobiosis occur with greater frequency in enriched compared to unenriched areas.

Ecosystem Metabolism and Turnover of Organic Carbon along a Blackwater River Continuum

Variation in ecosystem metabolism and organic carbon turnover length was examined in the Ogeechee River (Georgia, USA) basin, a sixth—order blackwater river, to determine if the patterns observed in other rivers are also seen along a river continuum characterized by warm water temperatures, low stream gradient, extensive riparian swamps, and tea—colored water. The study was in two parts: an intensive study of seasonal variation in metabolism and organic carbon turnover length at a fourth—order site, which can be compared with an earlier study at a sixth—order site, and a study of the variation in system metabolism at five second— through sixth—order sites along the continuum. Metabolism varied seasonally at the fourth—order site that was studied most intensively; mean gross primary production (GPP, measured as O2) was 0.8 g°m—2°d—1 and mean community respiration (CR, also measured as O2) was 4.1 g°m—2°d—1. The community production/respiration ratio (P/R) ranged from 0.02 to 0.4 with an annual mean of 0.2. This is clearly a heterotrophic stream reach, where high rates of community respiration are supported by inputs of organic matter from extensive riparian swamps. Mean annual organ carbon turnover length at the fourth—order site was 570 km, although on most dates the length was much less, with a median of 114 km. Turnover lengths are significantly less than those at the sixth—order site, but much greater than observed in other rivers of similar size, probably because most of the organic carbon export in this river is dissolved organic carbon (DOC), which is less efficiently retained. Seasonal variation in turnover length reflected variation in transport. At five sites along the Ogeechee River continuum ranging from second to sixth order, GPP, CR, and P/R increased with stream order, as observed in other rivers; yet P/R was always &lt;1, and net daily metabolism was always negative and became more negative with increasing stream order. In contrast to other river continua studied, metabolism in this low—gradient blackwater river becomes more dependent on allochthonous organic carbon with increasing stream size despite downstream increases in GPP; floodplains and riparian swamps appear to be the source of allochthonous carbon. Riparian influences increase rather than decrease along the continuum in this river. Although first—through third—order streams represent 32% of the channel area in the Sixth—order basin, only 4% of basin—wide GPP and 9% of basin—wide CR occurs in them. Higher order streams are less efficient in organic carbon processing (longer turnover lengths), but are nonetheless responsible for most of the metabolic activity in this river basin.

Autotrophlc-Heterotrophic Community Metabolism Relationships of a Woodland Stream

ABSTRACT Using an in situ chamber oxygen method at five first through third order stream riffle sites in Augusta Creek, Michigan, estimates of community metabolism were made on a monthly or seasonal basis (1973–1975). Net community productivity (NCP) ranged from −0.25 to 4.03 gO2m −2d−1, community respiration (CR) from 0.24 to 3.67 gO2m 2d1, and gross community productivity (GCP) from 0.09 to 5.35 gO2m −2d−1. The integrative parameters net daily metabolism (NDM) and ratio of GCP to 24 hour CR (P/R) ranged from −0.72 to 2.68 gO2m −2d−1 and 0.017 to 2.5, respectively and remained relatively constant at each site. Most parameters were consistently low and stable at first order sites, while autotrophic sites differed significantly. The first order sites were heterotrophic (P/R<1) with negative NDM. The meadow second order site was autotrophic with little capacity for export, illustrated by low NDM. Both third order sites (wooded and cleared) were autotrophic, but the cleared site had a higher NDM.

Benthic Community Metabolism in Two Northern Mississippi Streams

ABSTRACT Seasonal estimates of metabolism were determined with closed, replicate, 12-liter recirculating chambers on an artificially constructed gravel bar in a seventh order stream, the Tombigbee River, and on a natural riffle in a fourth order stream, the Buttahatchie River. In the Tombigbee and Buttahatchie rivers, the respective ranges for metabolism parameters were as follows (in g 02m−2 d−1): gross community primary productivity, 0.39 to 2.97 and 0.06 to 0.44; net community primary productivity, −0.72 to 2.38 and −0.50 to 0.11; community respiration, 0.60 to 6.00 and 0.24 to 1.04; net daily metabolism, −3.22 to 1.61 and −0.90 to −0.01; and ratios of gross community primary productivity to 24 hour community respiration (P/R), 0.38 to 2.01 and 0.09 to 0.98. Stepwise multiple linear regression indicated that most of the variation in metabolism parameters was explained by temperature, detritus, substrate-level light, and total Kjeldahl nitrogen in the Buttahatchie River, and by turbidity, temperature, c...

Benthic community metabolism in four temperate stream systems: An inter-biome comparison and evaluation of the river continuum concept

Benthic community metabolism was studied on four stream systems located in different biomes in the United States: the eastern deciduous forest (Pennsylvania, PA, and Michigan, MI), the high desert (Idaho, ID), and the coniferous forest (Oregon, OR). Studies were designed to test the hypothesis advanced within the River Continuum Concept that a transition in community metabolism will occur from a predominance of heterotrophy in headwaters to a predominance of autotrophy in mid-sized reaches, with a return to heterotrophy further downstream. Both gross primary productivity (GPP) and community respiration (CR24) increased with downstream direction on all systems. Net daily metabolism (NDM, or GPP − CR24) shifted from heterotrophy (−NDM, GPP CR24) with downstream direction at all sites, supporting the hypothesis. Annual metabolism in the most upstream reach of all sites was dominated by respiration; however, the farthest downstream reach was not necessarily the most autotrophic. Site-specific factors affected manifestation of the trend. Photosynthesis predominated annual metabolism in reaches (designated 1–4 in order of increasing size) 2–4 in ID, 3 and 4 in OR, and 4 in MI. In PA annual photosynthesis was slightly greater than respiration only at Station 3. Photosynthesis was predominant most consistently in ID and respiration most often in PA. About half the reaches that were heterotrophic annually were autotrophic at one or more seasons. Annual means of benthic GPP, CR24 and NDM ranged from 0.16 to 3.37, 0.36 to 2.88 and −0.73 to 0.50 g O2 · m2 · d1, respectively. Metabolic rates were usually high in PA and MI (and sometimes ID) and almost always lowest in OR. Parameters accounting for most variance in multiple linear regression analyses of the combined metabolism data from all sites were indicators of stream size, photosynthetically active radiation, temperature, and chlorophyll a concentration.

Estimates of ecosystem metabolism in the La Trobe River, Victoria

Diel oxygen-curve techniques were used to estimate gross primary productivity (PG), community respiration and net daily metabolism (NDM) for five reaches of the La Trobe River from headwaters to lowlands. All reaches were heterotrophic throughout the study (December 1980-November 1981) with NDM ranging from - 1 to -6 g O2 m-2. PG was consistently very low at the most upstream station and highest in the middle reaches of the river, where both benthic and planktonic contributions were important. At the most downstream station benthic productivity was negligible but planktonic productivity was appreciable in spring and autumn. PG in the river may be limited in the upper reaches by lack of light (due to shading by vegetation) and low levels of nutrients, and in the lower reaches by turbidity and increased depth.

Relationships Between Metabolic Parameters and Stream Order in Oregon

The light regime, standing stock of chlorophyll, and five metabolic parameters were measured seasonally at four Oregon stream sites; Devils Club Creek (1st order), Mack Creek (3rd order), Lookout Creek (5th order), and the McKenzie River (7th order). Periphyton from pools and riffles, aquatic moss (Fontinalis), fine particulate organic matter (FPOM: 0.5 μm–1 cm), and coarse particulate organic matter (CPOM: &gt; 1 cm) were examined separately for gross production (GP), net community production (NCP), diel respiration (R24), net daily metabolism (NDM), and the production to respiration (P:R) ratio. Total autotrophic production was found to increase in a downstream direction where more light is available; however, the efficiency of light utilization is greatest in heavily shaded Mack Creek. Detrital metabolism, per unit weight, is similar in all streams for each metabolic parameter. The standing stock of detritus though, is highest in headwater streams, decreasing as streams become larger. Therefore, the relative contribution of the detritus community to total metabolism decreases downstream. Mosses occur in significant quantities only in the McKenzie River and have an areal community respiration rate about twice that of periphyton; other metabolic parameters are nearly equal in this case. On an areal basis periphyton metabolism is much greater than detrital metabolism and, as a consequence, total stream metabolism and the P:R ratio increase downstream.Gross production rates measured for these sites are some of the lowest recorded (0.1–1.0 g O2∙m−2∙d−1). These rates are compared to those from other streams in the northwestern United States and western Canada, and the importance of photosynthesis to stream systems is demonstrated. The decomposition rate of the detrital standing stock is estimated to be 0.0029–0.0057%∙m−2∙d−1 and the turnover time is calculated to be 48–93 yr for particles &lt; 10 cm in diameter.Key words: streams, rivers, metabolism, primary production, detritus, photosynthesis, chlorophyll, respiration, light, Oregon