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1.
Comparative study of periphyton community structure in long and short-hydroperiod Everglades marshes 总被引:1,自引:0,他引:1
The Florida Everglades is a mosaic of short and long-hydroperiod marshes that differ in the depth, duration, and timing of
inundation. Algae are important primary producers in widespread Everglades’ periphyton mats, but relationships of algal production
and community structure to hydrologic variability are poorly understood. We quantified differences in algal biomass and community
structure between periphyton mats in 5 short and 6 long-hydroperiod marshes in Everglades National Park (ENP) in October 2000.
We related differences to water depth and total phosphorus (TP) concentration in the water, periphyton and soils. Long and
short-hydroperiod marshes differed in water depth (73 cm vs. 13 cm), periphyton TP concentrations (172μg g−1 vs. 107 μg g−1, respectively) and soil TP (284 μg g−1 vs. 145 μg g−1). Periphyton was abundant in both marshes, with short-hydroperiod sites having greater biomass than long-hydroperiod sites
(2936 vs. 575 grams ash-free dry mass m−2). A total of 156 algal taxa were identified and separated into diatom (68 species from 21 genera) and “soft algae” (88 non-diatom
species from 47 genera) categories for further analyses. Although diatom total abundance was greater in long-hydroperiod mats,
diatom species richness was significantly greater in short- hydroperiod periphyton mats (62 vs. 47 diatom taxa). Soft algal
species richness was greater in long-hydroperiod sites (81 vs. 67 soft algae taxa). Relative abundances of individual taxa
were significantly different among the two site types, with soft algal distributions being driven by water depth, and diatom
distributions by water depth and TP concentration in the water and periphyton. Periphyton communities differ between short
and long-hydroperiod marshes, but because they share many taxa, alterations in hydroperiod could rapidly promote the alternate
community.
Electronic supplementary material Electronic supplementary material is available for this article at
and accessible for authorised users. 相似文献
2.
The Status and Characteristics of Eutrophication in the Yangtze River (Changjiang) Estuary and the Adjacent East China Sea, China 总被引:19,自引:0,他引:19
Eutrophication has become increasingly serious and noxious algal blooms have been of more frequent occurrence in the Yangtze
River Estuary and in the adjacent East China Sea. In 2003 and 2004, four cruises were undertaken in three zones in the estuary
and in the adjacent sea to investigate nitrate (NO3–N), ammonium (NH4–N), nitrite (NO2–N), soluble reactive phosphorus (SRP), dissolved reactive silica (DRSi), dissolved oxygen (DO), phytoplankton chlorophyll
a (Chl a) and suspended particulate matter (SPM). The highest concentrations of DIN (NO3–N+NH4–N+NO2–N), SRP and DRSi were 131.6, 1.2 and 155.6 μM, respectively. The maximum Chl a concentration was 19.5 mg m−3 in spring. An analysis of historical and recent data revealed that in the last 40 years, nitrate and SRP concentrations increased
from 11 to 97 μM and from 0.4 to 0.95 μM, respectively. From 1963 to 2004, N:P ratios also increased from 30–40 up to 150. In parallel with the N and P enrichment,
a significant increase of Chl a was detected, Chl a maximum being 20 mg m−3, nearly four times higher than in the 1980s. In 2004, the mean DO concentration in bottom waters was 4.35 mg l−1, much lower than in the 1980s. In comparison with other estuaries, the Yangtze River Estuary was characterized by high DIN
and DRSi concentrations, with low SRP concentrations. Despite the higher nutrient concentrations, Chl a concentrations were lower in the inner estuary (Zones 1 and 2) than in the adjacent sea (Zone 3). Based on nutrient availability,
SPM and hydrodynamics, we assumed that in Zones 1 and 2 phytoplankton growth was suppressed by high turbidity, large tidal
amplitude and short residence time. Furthermore, in Zone 3 water stratification was also an important factor that resulted
in a greater phytoplankton biomass and lower DO concentrations. Due to hydrodynamics and turbidity, the open sea was unexpectedly
more sensitive to nutrient enrichment and related eutrophication processes. 相似文献
3.
R. Jan Stevenson Steven T. Rier Catherine M. Riseng Richard E. Schultz Michael J. Wiley 《Hydrobiologia》2006,561(1):149-165
Responses of stream algal biomass to nutrient enrichment were studied in two regions where differences in hydrologic variability
cause great differences in herbivory. Around northwestern Kentucky (KY) hydrologic variability constrains invertebrate biomass
and their effects on algae, but hydrologic stability in Michigan (MI) streams permits accrual of high herbivore densities
and herbivory of benthic algae. Multiple indicators of algal biomass and nutrient availability were measured in 104 streams
with repeated sampling at each site over a 2−month period. Many measures of algal biomass and nutrient availability were positively
correlated in both regions, however the amount of variation explained varied with measures of biomass and nutrient concentration
and with region. Indicators of diatom biomass were higher in KY than MI, but were not related to nutrient concentrations in
either region. Chl a and % area of substratum covered by Cladophora were positively correlated to nutrient concentrations in both regions. Cladophora responded significantly more to nutrients in MI than KY. Total phosphorus (TP) and total nitrogen (TN) explained similar
amounts of variation in algal biomass, and not significantly more variation in biomass than dissolved nutrient concentrations.
Low N:P ratios in the benthic algae indicated N as well as P may be limiting their accrual. Most observed responses in benthic
algal biomass occurred in nutrient concentrations between 10 and 30 μg TP l−1 and between 400 and 1000 μg TN l−1. 相似文献
4.
Algal-periphyton population and community changes from zinc stress in stream mesocosms 总被引:3,自引:3,他引:0
Three treatments of zinc (0.05, 0.5, 1.0 mg Zn l−1) and a control could be identified by different algal communities in outdoor, flow-through, stream mesocosms. Established
communities were continuously exposed to Zn, and samples were collected on days 0, 2, 5, 10, 20 and 30 after treatment began.
Experiments were conducted in spring, summer, and fall 1984. Control stream mesocosms could be identified by diatoms in all
seasons. The 0.05 mg Zn l−1 treatment could be identified by certain diatom taxa being more abundant than in the control in all seasons and by a filamentous
green alga in summer and fall. The 0.5 mg Zn l−1 treatment could be identified by a filamentous green alga in fall. The 1.0 mg Zn l−1 treatment was dominated by unicellular green algae in all seasons and by a filamentous blue-green alga in summer. A similarity
index (SIMI) indicated that Zn-stressed samples generally became less similar to control samples as Zn concentration increased
from 0.05 to 1.0 mg Zn l−1. Total biovolume-density of all taxa responded slower than individual taxa in spring and failed to distinguish between Zn
treatments in summer and fall. Zinc bound to periphyton was much better than total Zn in water for identifying Zn treatments.
Zinc treatments as low as 0.05 mg Zn l−1 changed algal species composition despite 0.047 mg Zn l−1 being the Criterion of the US Environmental Protection Agency for the 24-h average of total recoverable Zn. 相似文献
5.
Influence of suspended clay on phosphorus uptake by periphyton 总被引:1,自引:0,他引:1
We investigated the effect of suspended clay upon the phosphorus uptake rate exhibited by lotic periphyton communities. Suspended
inorganic clays and periphyton are common to aquatic environments, and both can strongly influence physical and chemical water
conditions. We used replicated artificial stream channels to test the prediction that suspended clay particles would affect
the uptake of soluble reactive phosphorus (SRP) by periphyton. Commercially available kaolinite and bentonite clays were characterized
for their aqueous suspension behavior and affinities for SRP. Periphyton was grown in a recirculating stream system and subjected
to simultaneous suspended clay and SRP additions. SRP removal from solution, both in the presence and absence of suspended
clays, was used to quantify SRP uptake parameters by periphyton. Clay type and concentrations of 20, 80, and 200 mg l−1 had no significant effect upon SRP uptake rate exhibited by periphyton during three 90-min experiments. Less than 1% of SRP
removal was attributable to the suspended clay load or artificial stream construction materials, based on clay isotherm data
and material sorption studies, indicating that 99% of SRP removal was attributable to biotic uptake. Removal of SRP (as KH2PO4) was described by a first-order equation with rate constants ranging between 0.02 and 0.14 min−1. Our results suggest that high turbidity conditions caused by suspended mineral clays have little immediate effect upon SRP
removal from the water column by periphyton.
Handling editor: D. Ryder 相似文献
6.
Frank Triska Catherine M. Pringle John H. Duff Ronald J. Avanzino Gary Zellweger 《Biogeochemistry》2006,81(2):145-157
Soluble reactive phosphorus (SRP) transport/retention was determined in two rain forest streams (Salto, Pantano) draining La Selva Biological Station, Costa Rica. There, SRP levels can be naturally high due to groundwater enriched by geothermal activity within the surfically dormant volcanic landscape, and subsequently discharged at ambient temperature. Combined field and laboratory approaches simulated high but natural geothermal SRP input with the objective of estimating the magnitude of amended SRP retention within high and low SRP settings and determining the underlying mechanisms of SRP retention. First, we examined short-term SRP retention/transport using combined SRP-conservative tracer additions at high natural in situ concentrations. Second, we attempted to observe a DIN response during SRP amendment as an indicator of biological uptake. Third, we determined SRP release/retention using laboratory sediment assays under control and biologically inhibited conditions. Short-term in situ tracer-SRP additions indicated retention in both naturally high and low SRP reaches. Retention of added SRP mass in Upper Salto (low SRP) was 17% (7.5 mg-P m−2 h−1), and 20% (10.9 mg-P m−2 h−1) in Lower Salto (high SRP). No DIN response in either nitrate or ammonium was observed. Laboratory assays using fresh Lower Salto sediments indicated SRP release (15.4 ± 5.9 μg-P g dry wt.−1 h−1), when incubated in filter sterilized Salto water at ambient P concentration, but retention when incubated in filter sterilized river water amended to 2.0 mg SRP l−1 (233.2 ± 5.8 μg-P g dry wt.−1 h−1). SRP uptake/release was similar in both control- and biocide-treated sediments indicating predominantly abiotic retention. High SRP retention even under biologically saturated conditions, absence of a DIN response to amendment, patterns of desorption following amendment, and similar patterns of retention and release under control and biologically inhibited conditions all indicated predominantly abiotic P flux. 相似文献
7.
Effects of hydrologic and water quality drivers on periphyton dynamics in the southern Everglades 总被引:2,自引:2,他引:0
David M. Iwaniec Daniel L. Childers Damon Rondeau Christopher J. Madden Colin Saunders 《Hydrobiologia》2006,569(1):223-235
Everglades periphyton mats are tightly-coupled autotrophic (algae and cyanobacteria) and heterotrophic (eubacteria, fungi
and microinvertebrates) microbial assemblages. We investigated the effect of water column total phosphorus and nitrogen concentrations,
water depth and hydroperiod on periphyton of net production, respiration, nutrient content, and biomass. Our study sites were
located along four transects that extended southward with freshwater sheetflow through sawgrass-dominated marsh. The water
source for two of the transects were canal-driven and anchored at canal inputs. The two other transects were rain-driven (ombrotrophic)
and began in sawgrass-dominated marsh. Periphyton dynamics were examined for upstream and downstream effects within and across
the four transects. Although all study sites were characterized as short hydroperiod and phosphorus-limited oligotrophic,
they represent gradients of hydrologic regime, water source and water quality of the southern Everglades. Average periphyton
net production of 1.08 mg C AFDW−1 h−1 and periphyton whole system respiration of 0.38 mg C AFDW−1 h−1 rates were net autotrophic. Biomass was generally highest at ombrotrophic sites and sites downstream of canal inputs. Mean
biomass over all our study sites was high, 1517.30 g AFDW m−2. Periphyton was phosphorus-limited. Average periphyton total phosphorus content was 137.15 μg P g−1 and average periphyton total N:P ratio was 192:1. Periphyton N:P was a sensitive indicator of water source. Even at extremely
low mean water total phosphorus concentrations ( ≤ 0.21 μmol l−1), we found canal source effects on periphyton dynamics at sites adjacent to canal inputs, but not downstream of inflows.
These canal source effects were most pronounced at the onset of wet season with initial rewetting. Spatial and temporal variability
in periphyton dynamics could not solely be ascribed to water quality, but was often associated with both hydrology and water
source. 相似文献
8.
Phosphorus (P) dynamics in large shallow lakes are greatly influenced by physical processes such as wind-driven sediment resuspension,
at times scales from hours to years. Results from long-term (30 year) research on Lake Okeechobee, Florida (area 1,730 km2, mean depth 2.7 m) illustrate key features of these P dynamics. Variations in wind velocity result in changes in water column
transparency, suspended solids, and total P (TP). In summer there are diurnal changes in TP associated with afternoon winds,
and in winter, when strong winds occur for multiple days, monthly average TP remains high compared to summer. The magnitude
of daily and seasonal TP changes can exceed 100 μg l−1. Hurricanes and tropical storms also cause extreme changes in TP that are superimposed on seasonal dynamics. When a hurricane
passed 80 km south of the lake in October 1999, mean pelagic TP increased from 88 to 222 μg l−1. During large resuspension events, light attenuation is substantially increased, and this influences the biomass and spatial
extent of submerged plants, as well as water column TP. In Lake Okeechobee, TP concentrations typically are ∼20 μg l−1 when submerged plants are dense, and soluble reactive P concentrations are reduced below detection, perhaps by the periphyton
and plant uptake and by precipitation with calcium at high pH. In contrast, TP exceeds 50 μg l−1 when submerged plants and periphyton are absent due to prolonged deep water, and phytoplankton biomass and algal bloom frequency
both are increased. In Lake Okeechobee and other large shallow lakes, complex models that explicitly consider wind-wave energy,
hydrodynamics, and sediment resuspension, transport, and key biological processes are needed to accurately predict how lake
water TP will respond to different management options. 相似文献
9.
Periphyton biomass and ecological stoichiometry in streams within an urban to rural land-use gradient 总被引:2,自引:0,他引:2
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 NO3
− and NH4
+ 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/m2 AFDM and 75.6 ± 28.5 mg/m2 Chl-a. Urban Chl-a levels ranging between 100 and 200 mg/m2, 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 μmol/mm2) 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. 相似文献
10.
Cristina Barrón Núria Marbà Carlos M. Duarte Morten F. Pedersen Cecilia Lindblad Kees Kersting Frithof Moy Tor Bokn 《Ecosystems》2003,6(2):0144-0153
We studied the effect of nutrient inputs on the carbon (C) budget of rocky shore communities using a set of eight large experimental
mesocosms. The mesocosms received a range of inorganic nitrogen (N) and phosphorus (P) additions, at an N:P ratio of 16. These
additions were designed to elevate the background concentration, relative to that in eutrophic Oslofjord (Norway) waters,
by 1, 2, 4, 8, 16, 32 μmol dissolved inorganic nitrogen (DIN)l−1 (and the corresponding P increase). Two unamended mesocosms were used as controls. The nutrients were added continuously
for 27 months before gross primary production (GPP), respiration (R), net community production (NCP), and dissolved organic
carbon (DOC) production were assessed for the dominant algal species (Fucus serratus) and for the whole experimental ecosystem. Inputs and outputs of DOC and particulate organic carbon (POC) from the mesocosms
were also quantified. The F. serratus communities were generally autotrophic (average P/R ratio = 1.33 ± 0.12), with the GPP independent of the nutrient inputs
to the mesocosms, and maintained a high net DOC production during both day (0.026 ± 0.008 g C m−2 h−1) and night (0.015 ± 0.004 g C m−2 h−1). All the experimental rocky shore ecosystems were autotrophic (P/R ratio = 2.04 ± 0.28), and neither macroalgal biomass
nor production varied significantly with increasing nutrient inputs. Most of the excess production from these autotrophic
ecosystems was exported from the systems as DOC, which accounted for 69% and 58% of the NCP of the dominant community and
the experimental ecosystem, respectively, the rest being lost as POC. High DOC release and subsequent export from the highly
energetic environments occupied by rocky shore communities may prevent the development of eutrophication symptoms and render
these communities resistant to eutrophication.
Received 10 October 2001; accepted 18 July 2002. 相似文献
11.
Sou Nagasoe Tomoyuki Shikata Yasuhiro Yamasaki Tadashi Matsubara Yohei Shimasaki Yuji Oshima Tsuneo Honjo 《Hydrobiologia》2010,651(1):225-238
We investigated the impact of different nitrogen (N) and phosphorus (P) compounds and concentrations on the growth of Gyrodinium instriatum Freudenthal et Lee in laboratory experiments, and possible links to blooms of this species at Hakozaki Fishing Port, Fukuoka,
Japan. G. instriatum utilized only inorganic N compounds as N sources for growth. In contrast, G. instriatum utilized many inorganic and organic phosphorus compounds. We used the Monod equation to describe the growth rate of G. instriatum in N- or P-limited batch cultures as a function of ambient nutrient concentrations. Kinetic growth parameters for maximum
specific growth rate (μmax) and half-saturation nutrient concentration (K
S) were 0.57 divisions d−1 and 14.2 μmol l−1, respectively, under N-limitation and 0.65 divisions d−1 and 1.75 μmol l−1, respectively, under P-limitation. Compared with these K
S values, all in situ average dissolved inorganic nitrogen (DIN) concentrations in Hakozaki Fishing Port were higher than K
S for N, but all in situ average dissolved inorganic phosphorus (DIP) concentrations were lower than K
S for P, whether a red tide occurred or not bloom. Moreover, average DIP concentration in April (a month critical to red-tide
genesis) of 2004 (a non-red-tide year) was less than half those in 2002 and 2003 (red-tide years). Thus, differences in DIP
concentrations may be an important factor controlling blooms of G. instriatum in Hakozaki Fishing Port. 相似文献
12.
Elizabeth Kebede-Westhead Carolina Pizarro Walter W. Mulbry 《Journal of applied phycology》2006,18(1):41-46
Cultivating algae on nitrogen (N) and phosphorus (P) in animal manure effluents presents an alternative to the current practice of land application. The objective of this study was to determine how algal productivity, nutrient removal efficiency, and elemental composition of turf algae change in response to different loading rates of raw swine manure effluent. Algal biomass was harvested weekly from laboratory scale algal turf scrubber units using four manure effluent loading rates (0.24, 0.40, 0.62 and 1.2 L m−2 d−1) corresponding to daily loading rates of 0.3–1.4 g total N and 0.08–0.42 g total P. Mean algal productivity values increased from 7.1 g DW m−2 d−1 at the lowest loading rate (0.24 L m−2 d−1) to 9.4 g DW m−2 d−1 at the second loading rate (0.40 L m−2 d−1). At these loading rates, algal N and P accounted for> 90% of input N and 68–76% of input P, respectively. However, at higher loading rates algal productivity did not increase and was unstable at the highest loading rate. Mean N and P contents in the dried biomass increased 1.5 to 2.0-fold with increasing loading rate up to maximums of 5.7% N and 1.8% P at 1.2 L m−2 d−1. Biomass concentrations of Al, Ca, Cd, Fe, K, Mg, Mn, Mo, Si, and Zn increased 1.2 to 2.6-fold over the 5-fold range of loading rate. Biomass concentrations of Cd, K, Pb, and Si did not increase significantly with loading rate. At the loading rate of 0.40 L m−2 d−1 (corresponding to peak productivity) the mean concentrations of individual components in the algal biomass were (in mg kg−1): 250 (Al), 4900 (Ca), 0.30 (Cd), 1050 (Fe), 3.4 (Pb), 2500 (Mg), 105 (Mn), 6.0 (Mo), 7,500 (K), and 510 (Zn). At these concentrations, heavy metals in the algal biomass would not be expected to reduce its value as a soil or feed amendment. 相似文献
13.
The principal environmental factors influencing the seasonal dynamics of phytoplankton were examined from September 1997 to
July 1998 in three stations along a 26-km stretch of the lowland course of River Adige (northeast Italy). Nutrient concentrations
did not appear to be limiting for the phytoplankton growth. Annual minimum concentrations of reactive and total phosphorus,
and dissolved inorganic nitrogen were 22 μg P l−1, 63 μg P l−1 and 0.9 mg N l−1, respectively. The most critical forcing factors were physical variables, mainly water discharge and other variables related
to hydrology, i.e. suspended solids and turbidity, which acted negatively and synchronously by diluting phytoplankton cells
and decreasing light availability. Higher algal biomass was recorded in early spring, in conditions of lower flow velocity
and increasing water temperature. In late spring and summer, higher water discharge caused a decrease in phytoplankton biomass.
Conversely, low algal biomass in late autumn and winter, during low discharge, was mainly related to low water temperatures
and shorter photoperiod. Physical constraints had a significant and measurable effect not only on the development of total
biomass, but also on the temporal dynamics of the phytoplankton community. Abiotic and biotic variables showed a comparable
temporal development in the three sampling stations. The small number of instances of spatial differences in phytoplankton
abundance during the period of lower flow velocity were related to the increasing importance of biological processes and accumulation
of phytoplankton biomass. 相似文献
14.
Nitrogen and phosphorus are the primary nutrients that affect water quality in streams in the midwestern USA and high concentrations
of these nutrients tend to increase algal biomass. However, how nutrients interact with physical controls in regulating algal
biomass is not well known in agricultural streams. Eighteen streams in east-central Illinois (USA) were sampled during June
and September 2003 to analyze factors possibly regulating algal biomass. Additionally, two shaded and two non-shaded sites
in the Embarras River in east-central Illinois were sampled intensively from June to December 2003. Both sestonic and periphytic
chlorophyll-a (chl-a) were analyzed, and periphytic chl-a was assessed on natural substrata and unglazed ceramic tiles. Although high concentrations of nutrients were found in these
streams (mean total P = 0.09–0.122 mg l−1 and mean NO3-N=4.4–8.4 mg l−1), concentrations of sestonic chl-a were low among all sites and both sampling periods (<18 mg m−3, median values of 5 and 3 in June and September, respectively). Filamentous algae were an important component of the algal
communities in streams with stable substrata. Periphytic chl-a was generally not related to the concentration of N or P in the water column, and in non-shaded streams periphyton appeared
at times to be light-limited due to turbid water. Turbidity was found to be an important factor controlling chl-a on ceramic tiles across the 18 sites and for the Embarras River sites; chl-a decreased exponentially in concentration (132–0 mg m−2) as turbidity increased from 4 to 39 NTU (r
2 = 0.80). In general, the interaction between hydrology and light (turbidity) likely controlled algal biomass in these nutrient-rich,
agricultural streams. 相似文献
15.
Vogelaar JC Klapwijk B Temmink H van Lier JB 《Journal of industrial microbiology & biotechnology》2003,30(2):81-88
Kinetic parameters describing growth and decay of mesophilic (30°C) and thermophilic (55°C) aerobic biomass were determined
in continuous and batch experiments by using oxygen uptake rate measurements. Biomass was cultivated on a single soluble substrate
(acetate) in a mineral medium. The intrinsic maximum growth rate (μ
max) at 55°C was 0.71±0.09 h−1, which is 1.5 times higher than the μ
max at 30°C (0.48±0.11 h−1). The biomass decay rates increased from 0.004 h−1 at 30°C to 0.017 h−1 at 55°C. Monod constants were very low for both types of biomass: 9±2 mg chemical oxygen demand (COD) l−1at 30°C and 3±2 mg COD l−1at 55°C. Theoretical biomass yields were similar at 30 and 55°C: 0.5 g biomass COD (g acetate COD)−1. The observed biomass yields decreased under both temperature conditions as a function of the cell residence time. Under
thermophilic conditions, this effect was more pronounced due to the higher decay rates, resulting in lower biomass production
at 55°C compared to 30°C.
Electronic Publication 相似文献
16.
The algal, protozoan and metazoan communities within different drift-ice types (newly formed, pancake and rafted ice) and
in under-ice water were studied in the Gulf of Bothnia in March 2006. In ice, diatoms together with unidentified flagellates
dominated the algal biomass (226 ± 154 μg ww l−1) and rotifers the metazoan and protozoan biomass (32 ± 25 μg ww l−1). The under-ice water communities were dominated by flagellates and ciliates, which resulted in lower biomasses (97 ± 25
and 21 ± 14 μg ww l−1, respectively). The under-ice water and newly formed ice separated from all other samples to their own cluster in hierarchical
cluster analysis. The most important discriminating factors, according to discriminant analysis, were chlorophyll-a, phosphate and silicate. The under-ice water/newly formed ice cluster was characterized by high nutrient and low chlorophyll-a values, while the opposite held true for the ice cluster. Increasing trends in chlorophyll-a concentration and biomass were observed with increasing ice thickness. Within the thick ice columns (>40 cm), the highest
chlorophyll-a concentrations (6.6–22.2 μg l−1) were in the bottom layers indicating photoacclimation of the sympagic community. The ice algal biomass showed additional
peaks in the centric diatom-dominated surface layers coinciding with the highest photosynthetic efficiencies [0.019–0.032 μg C (μg Chl-a
−1 h−1) (μE m−2 s−1)−1] and maximum photosynthetic capacities [0.43-1.29 μg C (μg Chl-a
−1 h−1)]. Rafting and snow-ice formation, determined from thin sections and stable oxygen isotopic composition, strongly influenced
the physical, chemical and biological properties of the ice. Snow-ice formation provided the surface layers with nutrients
and possibly habitable space, which seemed to have favored centric diatoms in our study. 相似文献
17.
TYLER J. KOHLER JUSTIN N. MURDOCK KEITH B. GIDO WALTER K. DODDS 《Freshwater Biology》2011,56(6):1133-1146
1. Anthropogenic activities in prairie streams are increasing nutrient inputs and altering stream communities. Understanding the role of large consumers such as fish in regulating periphyton structure and nutritional content is necessary to predict how changing diversity will interact with nutrient enrichment to regulate stream nutrient processing and retention. 2. We characterised the importance of grazing fish on stream nutrient storage and cycling following a simulated flood under different nutrient regimes by crossing six nutrient concentrations with six densities of a grazing minnow (southern redbelly dace, Phoxinus erythrogaster) in large outdoor mesocosms. We measured the biomass and stoichiometry of overstory and understory periphyton layers, the stoichiometry of fish tissue and excretion, and compared fish diet composition with available algal assemblages in pools and riffles to evaluate whether fish were selectively foraging within or among habitats. 3. Model selection indicated nutrient loading and fish density were important to algal composition and periphyton carbon (C): nitrogen (N). Nutrient loading increased algal biomass, favoured diatom growth over green algae and decreased periphyton C : N. Increasing grazer density did not affect biomass and reduced the C : N of overstory, but not understory periphyton. Algal composition of dace diet was correlated with available algae, but there were proportionately more diatoms present in dace guts. We found no correlation between fish egestion/excretion nutrient ratios and nutrient loading or fish density despite varying N content of periphyton. 4. Large grazers and nutrient availability can have a spatially distinct influence at a microhabitat scale on the nutrient status of primary producers in streams. 相似文献
18.
We performed a one-year study to determine the effects of on-site sewage disposal systems (OSDS, septic tanks) on the nutrient
relations of limestone groundwaters and nearshore surface waters of the Florida Keys. Monitor wells were installed on canal
residences with OSDS and a control site in the Key Deer National Wildlife Refuge on Big Pine Key. Groundwater and surface
water samples were collected monthly during 1987 and analyzed for concentrations of dissolved inorganic nitrogen (DIN = NOf3/sup- + NOf2/sup- + NH4/su+), soluble reactive phosphate (SRP), temperature and salinity.
Significant nutrient enrichment (up to 5000-fold) occurred in groundwaters contiguous to OSDS; DIN was enriched an average
of 400-fold and SRP some 70-fold compared to control groundwaters. Ammonium was the dominant nitrogenous species and its concentration
ranged from a low of 0.77 μM in control wells to 2.75 mM in OSDS-enriched groundwaters. Concentrations of nitrate plus nitrite
were also highly enriched and ranged from 0.05 μM in control wells to 2.89 mM in enriched groundwaters. Relative to DIN, concentrations
of SRP were low and ranged from 30 nM in control wells to 107 μM in enriched groundwaters. N : P ratios of enriched groundwaters
were consistently > 100 and increased with increasing distance from the OSDS, suggesting significant, but incomplete, adsorption
of SRP by subsurface flow through carbonate substrata.
Nutrient concentrations of groundwaters also varied seasonally and were approximately two-fold higher during the winter (DIN
= 1035 μM; SRP = 10.3 μM) compared to summer (DIN = 470 μM; SRP = 4.0 μM). In contrast, surface water nutrient concentrations
were two-fold higher during the summer (DIN = 5.0 μM; SRP = 0.50 μM) compared to winter (DIN = 2.5 μM; SRP = 0.15 μM).
Direct measurement of subsurface groundwater flow rate indicated that tides and increased groundwater recharge enhanced flow
some two-fold and six-fold, respectively. Accordingly, the observed seasonal coupling of OSDS-derived nutrients from groundwaters
to surface waters is maximum during summer because of seasonally maximum tides and increased hydraulic head during the summer
wet season. The yearly average benthic flux of anthropogenic DIN into contiguous canal surface waters is 55 mmol m-2 day-1, a value some five-fold greater than the highest rate of benthic N-fixation measured in carbonate-rich tropical marine waters. 相似文献
19.
José Juan Barrera-Alba Sônia Maria Flores Gianesella Gleyci Aparecida Oliveira Moser Flávia Marisa Prado Saldanha-Corrêa 《Hydrobiologia》2008,598(1):229-246
Heterotrophic bacterial and phytoplankton biomass, production, specific growth rates and growth efficiencies were studied
in July 2001 and January 2002 during both spring and neap tides, along a tidal cycle, at three sites in a subtropical estuary.
Major freshwater inputs located in the Northern region led to differences in both phytoplankton and bacterioplankton biomass
and activity along the estuary. While in the Northern region phytoplankton is light-limited, with mean phytoplankton production
(PP) between 1.1 and 1.9 μg C l−1 h−1 and mean specific growth rates (PSG) between 0.14 and 0.16 d−1, the Southern region registered values as high as 24.7 μg C l−1 h−1 for PP and 2.45 d−1 (mean PP between 3.4 and 7.3 μg C l−1 h−1; mean PSG between 0.28 and 0.57 d−1). On the other hand, maximum bacterial production (BP: 63.8 μg C l−1 h−1) and specific growth rate (BSG: 32.26 d−1) were observed in the Northern region (mean BP between 3.4 and 12.8 μg C l−1 h−1; mean BSG between 1.98 and 6.67 day−1). These bacterial activity rates are among the highest recorded rates in estuarine and coastal waters, indicating that this
system can be highly heterotrophic, due to high loads of allochthonous carbon (mainly derived from mangrove forest). Our results
also showed that, despite that BP rates usually exceeded PP, in the Southern region BP may be partially supported (∼45%) by
PP, since a significant regression was observed between BP and PP (r = 0.455, P < 0.001).
Handling editor: P. Viaroli 相似文献
20.
Changes in Nutrient Loading in an Agricultural Watershed and Its Effects on Water Quality and Stream Biota 总被引:3,自引:0,他引:3
P. A. Chambers R. Meissner F. J. Wrona H. Rupp H. Guhr J. Seeger J. M. Culp R. B. Brua 《Hydrobiologia》2006,556(1):399-415
Non-point-sources of nitrogen (N) and phosphorus (P) are recognized as major causes of eutrophication of surface waters. Adoption
of policies to reduce pollution in the former German Democratic Republic following re-unification of Germany in 1990 provided
an opportunity to examine how taking agricultural land out of production affected nutrient loads and aquatic biota in a small
rural watershed. Between 1994 and 1996, soluble reactive phosphorus (SRP) and dissolved inorganic nitrogen (DIN) loads in
a first-order agricultural stream decreased by >90% while instream concentrations decreased by 89% for DIN and 40% for SRP.
This reduction in nutrients coincided with a decrease in precipitation (from 760 to 440 mm between 1994 and 1996) and an increase
in the area of land set aside from agricultural production (from 0.3% in 1990 to a maximum of 8% in 1994). The biomass of
primary producers (episammic algae) showed no clear response to this decrease in nutrient concentrations. However, benthic
invertebrate composition shifted from a chironomid–amphipod to an oligochaete–gastropod dominated community in response to
the decrease in DIN and changes in episammic algal abundance and sediment organic carbon concentrations. Results from our
4-year study showed reductions in soil nutrient losses combined with less precipitation resulted in less P and N in a rural
stream and a change in benthic invertebrate community composition and abundance. 相似文献