Effects of N: P ratio and total nutrient concentration on stream periphyton community structure, biomass, and elemental composition (original) (raw)
Related papers
Inland Waters, 2013
The purpose of this study was to experimentally evaluate the effects of nutrient ratios and nutrient concentration (NC) on periphyton biomass using water from 4 Irish streams. Stream water nitrogen to phosphorus (N:P) ratios were manipulated (high >50, medium 15–30, low <10) and crossed with 3 different NCs over a 2-week period. Algal biomass as chlorophyll a (Chl-a) showed variable response to the treatments compared to the control in 3 streams and no response to the treatments in the forth stream. The 3 streams showed significant interaction between N:P ratio and NC. Periphyton response to the NC treatments and N:P ratio was varied; 2 streams had a significant response to both NC treatments and N:P ratios. In these 2 streams Chl-a was positively correlated to dissolved inorganic N but not to soluble reactive P, indicating N limitations despite the high N:P ratio from the ambient stream water. The third stream showed a significant response to NC and was again co-limited by N ...
Effect of periphyton biomass on hydraulic characteristics and nutrient cycling in streams
Oecologia, 1994
The effect of periphyton biomass on hydraulic characteristics and nutrient cycling was studied in laboratory streams with and without snail herbivores. Hydraulic characteristics, such as average water velocity, dispersion coefficients, and relative volume of transient storage zones (zones of stationary water), were quantified by performing short-term injections of a conservative tracer and fitting an advection-dispersion model to the conservative tracer concentration profile downstream from the injection site. Nutrient cycling was quantified by measuring two indices: (1) uptake rate of phosphorus from stream water normalized to gross primary production (GPP), a surrogate measure of total P demand, and (2) turnover rate of phosphorus in the periphyton matrix. These measures indicate the importance of internal cycling (within the periphyton matrix) in meeting the P demands of periphyton. Dense growths of filamentous diatoms and blue-green algae accumulated in the streams with no snails (high-biomass streams), whereas the periphyton communities in streams with snails consisted almost entirely of a thin layer of basal cells of Stigeoclonium sp. (low-biomass streams). Dispersion coefficients were significantly greater and transient storage zones were significantly larger in the high-biomass streams compared to the low-biomass streams. Rates of GPPnormalized P uptake from water and rates of P turnover in periphyton were significantly lower in high biomass than in low biomass periphyton communities, suggesting that a greater fraction of the P demand was met by recy-cling in the high biomass communities. Increases in streamwater P concentration significantly increased GPP-normalized P uptake in high biomass communities, suggesting diffusion limitation of nutrient transfer from stream water to algal cells in these communities. Our results demonstrate that accumulations of periphyton biomass can alter the hydraulic characteristics of streams, particularly by increasing transient storage zones, and can increase internal nutrient cycling. They suggest a close coupling of hydraulic characteristics and nutrient cycling processes in stream ecosystems.
Role of Nutrient Cycling and Herbivory in Regulating Periphyton Communities in Laboratory Streams
Ecology, 1991
In this study we examined the role of nutrient cycling and herbivory in regulating stream periphyton communities. Population, community, and ecosystem-level properties were studied in laboratory stream channels that had nutrient inputs reduced compared to channels where ambient nutrient levels were maintained. We reduced nutrient inputs in four of eight channels by recirculating 90% of the flow, whereas the other four channels received once-through flow of spring water. We examined the interaction between herbivory and nutrients by varying the number of snails (Elimia clavaeformis) among streams with different nutrient input (circulation) regimes.
Water, Air, and Soil Pollution, 1987
Two artificial streams simulating low-order, softwater streams of the Upper Peninsula of Michigan were employed to examine the effects of lowered pH on periphytic algae. The control stream contained water with a circumneutral pH whereas the pH of the water in the acidified stream was decreased to pH 4 with H2SO 4. Chlorophyll a concentrations and cell densities in the periphytic algal communities were used to measure differences in biomass accumulations between the 2 streams over a 42-d, spring colonization period. Relative abundances of algal genera and Stander's similarity index (SIMI) were used to examine compositional differences between the control and acidified periphytic algal communities. These algal communities exhibited pronounced differences in their total biomasses and compositions indicating that periphytic algal communities inhabiting low-order, softwater streams, such as those of the Upper Peninsula of Michigan, are vulnerable to acidic deposition. Decreased biomass accumulation under acidified conditions was believed to result primarily from decreased nutrient availability, and possibly secondarily from elevated aluminum and/or iron concentrations. The shift in community compositions was interpreted to be a more direct response to the lowered pH as acidophils and acid tolerant genera became favored, and thus more abundant.
2001
Nutrient-releasing artificial substrata were deployed in streams draining clearcut and forested watersheds to evaluate resources potentially limiting to populations of benthic algae. Nitrogen, phosphorus, and calcium were released singly and in combination in the two streams that differed primarily in light availability. Periphyton were harvested after one-and two-month exposure periods and analyzed for chlorophyll. The two-month substrata were additionally analyzed for algal community structure. Algal periphyton in the clearcut stream accumulated more chlorophyll and biovolume than in the forested stream across all nutrient treatments. Algal community structure was significantly different between streams but not between nutrient treatments. Algal physiognomies were also significantly different between streams with filamentous green algae dominating the clearcut stream and erect diatoms dominating the forested stream. Light appears to limit algal accumulation in the forested stream and there is evidence that some populations in the clearcut stream may be nutrient limited. Adequate light also resulted in a more architecturally diverse community.
Periphyton biomass and community composition in rivers of different nutrient status
Canadian Journal of Fisheries and Aquatic Sciences, 1999
Epilithic periphyton was investigated in riffle zones of 13 rivers in southern Ontario and western Quebec to describe how algal biomass and community composition vary with nutrient concentration and water velocity during summer. Algal biomass (milligrams chlorophyll a (Chl a) per square metre) was strongly correlated with total phosphorus concentration (r 2 = 0.56, p < 0.001) and conductivity (r 2 = 0.71, p < 0.001) of the overlying water but unrelated to water velocity over the range of 10-107 cm·s -1 . Differences in periphyton Chl a were associated with changes in biomass of Chlorophyta (r 2 = 0.51, p = 0.001) and Bacillariophyta (r 2 = 0.64, p < 0.001) and were not related to Rhodophyta and Cyanophyta biomass (p > 0.10). The relative proportions of taxonomic divisions varied with total standing stock. Percent Chlorophyta biomass increased with periphyton Chl a and was the largest fraction at moderately eutrophic sites. Rhodophyta contributed the most biomass at sites with the lowest Chl a. Cladophora, Melosira, and Audouinella biomasses were positively correlated with total phosphorus concentration over the range of 6-82 µg·L -1 (r 2 = 0.39-0.64, p < 0.005), and these genera were dominant at sites with the highest nutrient concentrations.
Effects of Light, Nutrients and Grazing on Periphyton Communities in Streams
Net daily metabolism under different grazing pressures. 48 18 Turnover times of periphyton under different grazing pressures. 50 19 Rates of gross primary production in relation to standing crops of chlorophyll a. 51 20 Assimilation number in relation to standing crops of chlorophyll a. 53 21a Ratios of absorbance at 480 nm to absorbance at 665 nm for heavily grazed and moderately grazed periphyton communities. 54 21b Ratios of absorbance at 480 nm to absorbance at 665 nm for periphyton communities exposed to low grazing pressures and no grazing. 54 22 Rates of growth and ingestion by snails at different standing crops of periphyton. 58 23 Relationships between biomass, growth rates and production. 62 24 Annual patterns of light intensity in the clearcut and old-growth sections of Mack Creek. 77 25 Annual patterns of stream temperature. 26 Annual patterns of precipitation. 79 27 Streamflow in Mack Creek. 28 Standing crops of chlorophyll a in the clearcut and old-growth forest sections of Mack Creek. 29 Biomass of periphyton in the clearcut and old-growth forest sections of Mack Creek. 30 Rates of Gross primary production in the clearcut and old-growth forest sections of Mack Creek. 84 31 Rates of net community primary production in the clearcut and old-growth forest sections of Mack Creek. 97 40 Assimilation number in the clearcut and old-growth forest sections of Mack Creek. 99 Page Rates of community respiration in the clearcut and 87 old-growth forest sections of Mack Creek. P/R ratios in the clearcut and old-growth forest sections of Mack Creek. 88 Net daily metabolism in the clearcut and old-growth forest sections of Mack Creek. 90 Concentration of organic matter in the drift in the clearcut and old-growth forest sections of Mack Creek. 91 Total output of organic matter from the clearcut and old-growth forest sections of Mack Creek. 91 Biomass of algae in the drift in the clearcut and old-growth forest section of Mack Creek. 93 Percent of the drift comprised by algae in the clearcut and old-growth forest sections of Mack Creek. 93 Concentrations of nitrate in the clearcut and old-growth forest sections of Mack Creek. 94 Concentrations of orthophosphate-phosphorus in the clearcut and old-growth forest sections of Mack Creek. 94 Alkalinity in the clearcut and old-growth forest sections of Mack Creek. 96 pH in the clearcut and old-growth forest sections of 96 Mack Creek.. chamber in the clearcut and old-growth forest sections Rates of uptake of nitrate by periphyton in the of Mack Creek.
Hydrobiologia, 2009
This study examined the effects land use on biomass and ecological stoichiometry of periphyton in 36 streams in southeastern New York State (USA). We quantified in-stream and land-use variables along a N-S land-use gradient at varying distances from New York City (NYC). Streams draining different landscapes had fundamentally different physical, chemical, and biological properties. Human population density significantly decreased (r =-0.739; P \ 0.00001), while % agricultural land significantly increased (r = 0.347; P = 0.0379) with northing. Turbidity, temperature, conductivity, and dissolved Mg, Ca, SRP, pH, DOC, and Si significantly increased in more urban locations, but NO 3 and NH 4 ? did vary not significantly along the gradient. Periphyton biomass (as AFDM and Chl-a) in rural streams averaged one-third to one-fifth that measured in urban locations. Periphyton biomass in urban streams averaged 18.8 ± 6.0 g/m 2 AFDM and 75.6 ± 28.5 mg/m 2 Chl-a. Urban Chl-a levels ranging between 100 and 200 mg/m 2 , are comparable to quantities measured in polluted agricultural streams in other regions, but in our study area was not correlated with % agricultural land. Periphyton nutrient content also varied widely; algal C varied [20-fold (0.06-1.7 lmol/mm 2) while N and P content varied [6-fold among sites. Algal C, N, and P correlated negatively with distance from NYC, suggesting that periphyton in urban streams may provide greater nutrition for benthic consumers. C:N ratios averaged 7.6 among streams, with 91% very close to 7.5, a value suggested as the optimum for algal growth. In contrast, periphyton C:P ratios ranged from 122 to [700 (mean = 248, twice Redfield). Algal-P concentrations were significantly greater in urban streams, but data suggest algal growth was P-limited in most streams regardless of degree of urbanization. GIS models indicate that land-use effects did not easily fit into strict categories, but varied continuously from rural to urban conditions. We propose that the gradient approach is the most effective method to characterize the influence of land use and urbanization on periphyton and stream function. Keywords Benthic algae Á Periphyton Á Rivers Á Land use Á Ecological stoichiometry Á Urban-rural gradient Á Nutrients Á New York
In situ nutrient assays of periphyton growth in a lowland Costa Rican stream
Nutrient limitation of primary production was experimentally assessed using an in situ bioassay technique in the Quebrada Salto, a third-order tropical stream draining the northern foothills of the Cordillera Centrall in Costa Rica . Bioassays employed artificial substrata enriched with nutrients that slowly diffuse through an agar-sand matrix . Multiple comparisons of regression coefficients, describing chlorophyll-a accrual through time for different nutrient treatments, revealed positive micronutrient effect(s) . Micronutrient treatment combinations (Fe, B, Mn, Zn, Co, Mo, EDTA), supplemented with and without nitrate and phosphate, exhibited significantly greater chlorophyll-a accrual over all other treatments (P < 0.05), supporting over three times that of the control after 14-d of substratum colonization . Neither of the major nutrients (N or P) produced a significant stimulation, although the N treatment displayed =50% more chlorophyll-a than the control after 14-d . Similarly, Si, EDTA, and Si + N + P treatments did not exhibit chlorophyll-a response curves that were significantly different from the control . During the experiment, mean NH4-N and (NO2 + NO 3)-N concentrations in the Salto were 2 .0 µM (28 .6 µg • 1 -') and 7.2 µM (100 .2 µg •1 -'), respectively. High concentrations of P0 4-P (x = 2 .0 µM ; 60 .9 µg •1 -') and TP (x = 3 .0 µM ; 94 .0 µg •1 -1 ) were also found, and consequently low molar N :P ratios (1-c = 4.7). Despite the potential for N limitation in the system, both N and P appear to be at growth saturating levels . This may be due to micronutrient limitation and/or light limitation of periphyton growth in densely shaded upstream portions of the stream .
Freshwater Biology, 2007
1. Nutrient diffusing substrata (NDS) were used to determine the relative importance of nutrients and light as potential limiting factors of periphyton biomass and nitrogen (N) uptake in Mediterranean streams subjected to different human impacts. The nutrients examined were phosphorus (P) and N, and we also further differentiated between the response of periphyton communities to N species (i.e. NO 3 -N and NH 4 -N). To examine the effect of light and nutrients on periphyton biomass, chlorophyll a accrual rates on NDS located at open and closed canopy sites were compared. The effect of nutrient availability on periphyton uptake was measured by 15 N changes on the NDS after NO 3 -15 N short-term nutrient additions. 2. Results show that light was the main factor affecting algal biomass in the study streams. Algal biomass was in general higher at open than at closed canopy sites. Nutrient availability, as simulated with the NDS experiments, did not enhance algal biomass accrual in either of the 2 light conditions. 3. In the control treatments (i.e. ambient concentrations), periphyton NO 3 -N uptake rates increased and C : N molar ratios decreased consistently with increases in N availability across streams. NO 3 -N uptake rates were altered when ambient N concentrations were increased artificially in the N amended NDS. Periphyton assemblages growing on N enriched substrata seemed to preferentially take up N diffusing from the substratum rather than N from the water column. This response differed among streams, and depended on ambient N availability. 4. Periphyton biomass was not significantly different between substrata exposed to the two forms of available N sources. Nonetheless, we found differences in the effects of both N sources on the uptake of N from the water column. NH 4 -N seemed to be the preferred source of N for periphyton growing on NDS. 5. Results suggest that the effect of riparian zones on light availability, although seldom considered by water managers, may be more important than nutrients in controlling eutrophication effects derived from human activities. Finally, our results confirm that not only increases in concentration, but also stoichiometric imbalances should be considered when examining N retention in human altered streams.