Limiting Nutrient Determination in Lotic Ecosystems Using a Quantitative Nutrient Enrichment Periphytometer (original) (raw)
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Periphyton response to nutrient manipulation in streams draining clearcut and forested watersheds
2000
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
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 ...
Limnology and Oceanography, 2001
The effects of nutrient ratios on algal community structure and algal growth have been examined extensively in lakes and marine environments, but rarely in streams. We manipulated stream water N : P ratio (65 : 1, 17 : 1, 4 : 1) and total nutrient concentration (low and high) in a factorial experiment using once-through streamside flumes and measured responses in abundance, community structure, and elemental composition of periphyton communities. Early in the experiment, periphyton chlorophyll a and total algal biovolume were higher for treatments where N was added (high total nutrient concentration) but were not affected by N : P ratio. This response is contrary to our prediction that P would limit periphyton growth based on the high N : P ratio in the source water and unamended periphyton mats. The relative abundance of nine of eleven common algal taxa was affected by N : P ratio, total nutrient concentration, or both. Overall, algal community structure was more sensitive than bulk measures of periphyton abundance to changes in N : P ratio and total nutrient concentration. Periphyton %N and %P increased with the N and P concentration of stream water, and periphyton N : P tracked stream water N : P ratio. Responses in periphyton chemical composition to nutrients could affect the food quality of periphyton for consumers.
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.
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.
Journal of the North American Benthological Society, 1992
Longitudinal gradients in streamwater nutrient concentrations in Walker Branch are generated as a result of instream nutrient uptake and spatially confined groundwater inputs during the period from November to May. The response of the stream periphyton community to these longitudinal nutrient reductions was determined by measuring periphyton biomass, productivity, species composition, and phosphorus (P) cycling indices at four stations along a longitudinal transect in the stream. Phosphorus cycling indices (chlorophyll-specific phosphatase activity, phosphorus content of periphyton) exhibited significant changes along the longitudinal transect during those times of the year when streamwater soluble reactive phosphorus (SRP) concentrations also decreased along the transect. During the period from June to October, however, neither streamwater phosphorus concentrations nor phosphorus cycling characteristics exhibited longitudinal trends. Regressions between phosphatase activity and streamwater SRP concentration and between phosphorus content and streamwater SRP were highly significant for all data combined, with SRP explaining >74% of the variation in phosphatase activity and P content. Measures of periphyton biomass (chlorophyll a, total biovolume), and productivity (areal carbon fixation rate, chlorophyll-specific carbon fixation rate) exhibited no consistent longitudinal patterns, even during the period of longitudinal streamwater phosphorus depletion. Regressions between productivity measures and streamwater SRP concentration for all data combined were significant, but SRP explained <56% of the variation in productivity. Periphyton biomass and productivity at all stations along the longitudinal transect appear to be maintained at low levels by high and longitudinally uniform rates of herbivory throughout the year. Algal species composition exhibited some response to longitudinal nutrient depletion. The biovolume and percentage of the blue-green alga Chamaesiphon investiens increased and the percentage of the chlorophyte Stigeoclonium sp. declined longitudinally when nutrients also declined. Our results demonstrate an upstream-downstream biotic linkage in Walker Branch. We show that instream nutrient uptake can reduce the concentrations of nutrients in stream water and thereby influence the structure and functioning of downstream periphyton communities. However, increases in nutrient cycling in response to lower streamwater concentrations can partially compensate for nutrient depletion by upstream organisms, thereby buffering primary productivity in downstream periphyton communities from changes in nutrient supply.
Journal of the North American Benthological Society, 2009
Many streams and rivers in the Pacific Northwest of the US are inherently oligotrophic, and primary production in these ecosystems is assumed to be nutrient-limited. In many of these streams, reductions in the amount of marine-derived nutrients delivered by spawning salmonids could be exacerbating the degree of oligotrophication. To test whether primary producers are nutrient-limited, nutrient diffusing substrate (NDS) experiments were used to measure algal responses to amendments of N, P, and a combination of N and P (N+P) in 13 Salmon River basin streams in central Idaho, USA. Thirtyeight experiments were conducted between 2003 and 2006 to determine whether nutrient limitation varied among streams and over time within individual streams. Primary producers in most streams showed some form of nutrient limitation. Thirty-nine percent of our experiments suggested N and P colimitation, 18% suggested N limitation, 11% suggested primary N and secondary P limitation, and 32% did not indicate limitation by either N or P. The type of nutrient limitation within individual streams varied with time, and the relative importance of N or P changed seasonally or annually in 7 of the 13 streams. Algal accrual rates on control and treatment substrates were most strongly predicted by water temperature, light, and ambient concentrations of N and P. Among all of the experiments, algal accrual rates were greater on N substrates in streams with lower ambient N concentrations and greater ambient P concentrations. Our results suggest that a combination of N and P typically limits primary producers in these streams. Our efforts to characterize current nutrient limitation in these streams will be of value to managers considering nutrient additions as a tool to improve stream productivity to benefit threatened and endangered salmonids.
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 .
Canadian Journal of Fisheries and Aquatic Sciences
1991. Interactive effects sf nutrient reduction and herbivory on biomass, taxonomic structure, and P uptake in lotic periphyton communities. Can. 1. Fish. Aquat. Sci. 48: 1951-1 959. Four treatments were imposed on eight laboratory streams in a factorial design to examine the roles of nutrient reduction and kerbivory on periphytsn communities. Treatments included two flow regimes (once-through flow or 90% recirculated water) and two levels of grazer density (1 0001 or OI.m-2, using the snail Elimia clavaeforrnis). Periphyton biomass was significantly greater in streams without snails than in those with them, but water supply had no overall significant effect on biomass, even though inorganic P and N concentrations were significantly lower in recirculated than in once-through streams. Areal-specific P uptake rates (measured with 3"P) were significantly greater on two dates in ns-snail streams compared with snail streams, presumably because of the greater biomass levels in the former systems. Differences in biomass-specific P uptake rates were not significantly affected by either grazer density or water supply. Relative abundances of most algal species were unaffected by the water supply treatment, although percent biovolume of two Epithernia species was greater in no-snail, recirculated than in no-snail, once-through streams. Grazing activity dramatically reduced the percent biovolurne of species with upright growth forms, resulting in dominance by species with prostrate growth forms.
Nutrient Limitation of Periphyton in a Spring-Fed, Coastal Stream in Florida, USA
Journal of Aquatic Plant Management
There is strong evidence to suggest that ground-water nitrate concentrations have increased in recent years and further increases are expected along portions of the central Gulf coast of Florida. Much of the nitrate enriched ground- water is discharged into surface waters through numerous freshwater springs that are characteristic of the area and the potential for eutrophication of their receiving waters is a legitimate concern. To test the potential effects of elevated nutrient concentrations on the periphyton community an in situ nutrient addition experiment was conducted in the spring-fed Chassahowitzka River, FL, USA, during the sum- mer of 1999. Plastic tubes housing arrays of glass microscope slides were suspended in the stream. Periphyton colonizing the microscope slides was subjected to artificial increases in nitrogen, phosphorus or a combination of both. Slides from each tube were collected at 3- to 4- day intervals and the periphyton communities were measured for chloroph...