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Bacterioplankton and Phytoplankton Populations in a Rapidly‐Flushed Eutrophic Reservoir
Abstract
Densities of bacterioplankton and phytoplankton were studied in relation to water retention time, temperature, nutrient concentrations, and other variables in a eutrophic montane reservoir (Bluestone Lake, West Virginia, U.S.A.). Weak temperature stratification occurred occasionally during the summer, but the reservoir did not become anaerobic. Water retention times were short (3.9 to 9.7 days between June and December), and differences in flushing rate within that range were important in regulating phytoplankton populations. Green algae and planktonic diatoms were dominant in summer during periods when water residence times were shorter. The occurrence of blue-green algal blooms in fall was related to increased water residence times. Retention time was highly correlated with the percent composition of phytoplankton represented by Anabaena spp. and Microcystis sp. (r=0.898, p<0.001). Advective effects limited phytoplankton biomass when retention time was shortest, but were not as important when retention times were longer. Peaks in bacterial densities often coincided with decreases in viable algal cell densities, so bacterioplankton were less directly related to retention time.
... Conversely, from May to August, the water column mixes. Cyanobacterial blooms generally occur when the retention time is longer, whereas diatoms and Chlorophyta have shorter retention times (Perry et al., 1990). ...
Climate projections models indicate that longer periods of droughts are expected within the next 100 years in various parts of South America. To understand the effects of longer periods of droughts on aquatic environments, we investigated the response of chlorophyll-a (Chl-a) concentration to recent severe drought events in the Barra Bonita Hydroelectric Reservoir (BBHR) in São Paulo State, Brazil. We used satellite imagery to estimate the Chl-a concentration from 2014 to 2020 using the Slope Index (NRMSE of 18.92% and bias of −0.20 mg m⁻³). Ancillary data such as precipitation, water level and air temperature from the same period were also used. Drought events were identified using the standardized precipitation index (SPI). In addition, we computed the probability of future drought events. Two periods showed extremely dry conditions: 1) January–February (2014) and 2) April–May (2020). Both periods were characterized by a recurrence probability of 1in every 50 years. The highest correlation was observed between Chl-a concentration and SPI (−0.97) in 2014, while Chl-a had had the highest correlation with water level (−0.59) in 2020. These results provide new insights into the influence of extreme drought events on the Chl-a concentration in the BBHR and their relationship with other climate variables and reservoir water levels. Drought events imply less rainfall, higher temperatures, and atmospheric dryness, and these factors affect evaporation and the water levels in the reservoir.
... Both Aulacoseira sp. and Stephanodiscus sp. were both found in high numbers in the river. Diatom species are favoured in high flow systems (Reif 1939;Perry et al. 1990;Reynolds et al. 1994;Rojo et al. 1994), because their strong skeletal structure allows them to be more resilient to the turbulent conditions of the river than any other phytoplankton group. Fragilaria crotonensis, a species which was a significant contributor to summertime biomass in eastern Lake Erie in 2008 and again in 2011 (Alliger and Reavie 2013), appears to survive the entire length of the Niagara River, as shown by its presence at NIA4 in August 2014. ...
This report collects all available plankton community data for the Niagara River Area of Concern (AOC) designated requires further assessment for the Beneficial Use Impairment (BUI 13): “degradation of phytoplankton and zooplankton populations”. The Niagara River connecting channel, though it joins well-studied Lake Erie and Lake Ontario is data-poor, with no active plankton sampling programs. A single season of sampling in 2014 took place monthly from June-Oct for water quality, zooplankton and phytoplankton composition and density. Oligotrophic conditions persisted throughout the season and plankton densities were extremely low, though this was expected in a high-flow system such as the Niagara River. The residence
time for plankton in the Niagara River is only 11-28 hours, but could be much longer if plankton are entrained in the hydroelectric reservoirs. Given the results of this survey, no impairment of plankton populations is indicated.
... d -1 is exceeded. However, Perry et al. (1990) reported that standing crops were limited by rates of cell export only at extremely high flushing rates (>0.25 d -1 ), and that the effects were not pronounced at 0.1-0.17 d -1 flushing rates. ...
Withdrawal is an important process in reservoir hydrodynamics, removing phytoplankton with flushed water. Zooplankton, the grazers of phytoplankton, having longer generation times, are even more susceptible than phytoplankton to flushing loss, therefore phytoplankton are affected not only by abiotic conditions linked to hydrodynamics but also by zooplankton due to weakened grazing pressure. During the Asian Games (November 12-27, 2010 in Guangzhou, China), two intensive epilimnetic withdrawals were conducted in Liuxihe, a deep canyon-shaped reservoir. To examine the influence of the intensive epilimnetic withdrawals on the phytoplankton community, a seven-week field observation and a hydrodynamic simulation were carried out. The observation was divided in two stages: stage 1 represented partial surface vertical mixing period, and stage 2 represented intensive epilimnetic withdrawal period. It was found that phytoplankton abundance and biomass declined with water temperature and partial surface vertical mixing in stage 1. However, the intensive epilimnetic withdrawal reversed this decreasing trend and increased phytoplankton biomass and abundance in stage 2. Phytoplankton showed a higher rate of composition change in stage 2. A numerical model (DYRESM-CAEDYM) simulated scenarios with and without epilimnetic withdrawal to test their effects on abiotic factors (water temperature, suspended sediment and soluble reactive phosphorus) for phytoplankton. The results showed no obvious difference in the abiotic factors between the two scenarios during stage 2. We therefore suggested that the abiotic factors in the water column were probably driven by a seasonal pattern, not by epilimnetic withdrawal. It is likely that the intensive epilimnetic withdrawal could remove large crustaceans. The reduced grazing pressure probably explained the increase of phytoplankton biomass and abundance after the withdrawal. Thus, we suggest that reservoir operation should pay more attention to grazing from large crustaceans. It is recommended that, in the management of reservoirs, intensive epilimnetic withdrawal during autumn should be avoided in order to control excessive phytoplankton in the tropics and subtropics.
... Besides this, higher flow rates and shorter water residence time tend to favour faster-growing diatom taxa (e.g. Perry et al., 1990). ...
Current efforts to yield an appropriate method that would simplify the use of phytoplankton in the ecological evaluation of freshwaters resulted in different approaches based on clustering phytoplankton organisms. In this study, we applied the morphology‐based functional group (MBFG) concept to determine the spatial changes of phytoplankton in the natural riverine floodplain of the alluvial reaches of the Danube River along the horizontal gradient from the river towards the floodplain habitats.
The obtained results showed that the magnitude of environmental changes depended on alternations in hydrological variables (hydropattern and water level) that influenced changes in the physical and chemical conditions. High‐intensity flood pulses caused environmental homogenizations and nitrate enrichment of the floodplain habitats. Phytoplankton dynamics were strongly associated with the environmental changes, and using the MBFG approach, two basic hydrological conditions were identified: inundation phase dominated by diatoms (GVI) and isolation phase dominated by filamentous cyanobacteria (GIII). Total diatom biomass decreased along the floodplain gradient with a diminishing of physical constraints, and site‐specific variables became more important in favouring diatom assemblages. The different response of cyanobacterial species to mixing regime was of particular significance for species successions during bloom period. Altogether, classifying very diverse diatoms (centrics and pennates and planktonic and benthic) and cyanobacterial taxa into single groups represents a weakness of the MBFG approach, which might make it impossible to reflect all the ecological differences governed by environmental constraints along river–floodplain gradients. Copyright © 2014 John Wiley & Sons, Ltd.
... In fact, the hydrologic conditions in 1997, reflected by the lower water retention time and increased hydraulic loading, may have selected against organisms with longer generation times (Basu and Pick, 1996) but may have favoured plankters with shorter generation times (phytoplankton, rotifers). However, water residence time in TDNP (131.4 days) exceeded the critical period needed for maturation of plankton communities (Perry et al., 1990;Basu and Pick, 1996), although water velocity can be high enough, particularly in spring, to dilute crustaceans in TDNP. Assuming that crustacean rinsing is negligible on a whole year basis, we suggest that dispersing mosquito fish populations, which occurred in 1997 (Alvarez-Cobelas, personal observation), effectively controlled crustacean biomass by predation (Meffe and Snelson, 1989;Rojo et al., 2000). ...
This study attempts to describe changes in plankton biomass (including bacteria, phyto- plankton, ciliates, rotifers, and crustaceans) in the semi-arid, hypertrophic, freshwater wetland, Las Tablas de Daimiel National Park (central Spain), in relation to water inflow. An inter-annual compari- son of 1996 and 1997, with contrasting rainfall, reveals that inflows in the form of flooding act as a bottom-up structuring force on total plankton biomass. However, the responses of plankton biomass to flooding were different in strength between the two years, which can be attributed to shifts in plankton community structure. Crustacean zooplankton conditioned total plankton biomass in 1996, based on the relationship between the high individual biomass and community development. Crust- aceans decreased in 1997, while bacteria, phytoplankton and rotifers increased. The quantitative increase of the latter groups resulted in a higher total plankton biomass in 1997. The key position of crustaceans in the wetland plankton is also reflected in their capability for exerting significant top- down control, which was clearly evident in 1996 but weaker in 1997, based on their numerical reduction. Statistical analyses provide evidence that the decline of trophic interactions in 1997 is related to the strength of flooding in that year, thereby highlighting the significance of the disruptive action of physical disturbance on biotic interactions in the plankton. Flooding and areal inundation were also shown to be significant for spatial heterogeneity. In 1996, site-specific development took place in the absence of prolonged flooding effects, resulting in high spatial heterogeneity. In 1997, however, remarkable homogenization of plankton biomass occurred along the major water flow path. Thus, wetland landscape heterogeneity depends on inflows which condition areal inundation. This, in turn, influences plankton dynamics.
... Similarly to other data reported (STRASKRABOVA, 1979, PERRY at al. 1990) the spatial and seasonal changes of the bacteria abundance are better expressed than the vertical gradient during the time of summer stratifi cation. Furthermore the seasonal changes (differences between spring and summer abundances) of bacterioplankton biomass were better expressed than the algal ones. ...
Some trophic characteristics as chlorophyll-a, Secchi-disk transparency, turbidity, phytoplankton and bacterioplabkton abundances were investigated during spring and summer of 2005 in three reservoirs in northeastern Bulgaria, suggested by the experts of the Ministry of Environment and Waters (MEW) as po-tential reference sites. Different characteristics show differences in the assessment of the reservoir trophic status as only Tsonevo seems to be appropriate to reference site on the basis of the most of characteristics studied. Secchi-disk transparency seems to be inappropriate for assessment of the ecological status of the studied water bodies without considering its different components especially at the time of spring high waters. It is necessary to separate clearly different zones (water bodies) of reservoirs, which strongly depend on the morphometry, seasons, retention time and development of their shoreline. Phytoplankton (both abundance and composition) seems to be a good indicator for the differentiation of reservoir zones. Bacterial contribution to some of investigated variables (e.g. turbidity) and bacteria-algae relationships were also studied. Indication for top-down control of mixotrophic algae on bacteria was obtained under conditions of P-limitation.
... In this regard, Abdel-Tawwab (2003) and Abdel-Tawwab and El-Marakby (2004) reported that Nile tilapia has the capability to select Cyanobacteria as a food item, in addition to Bacillariophyceae, Chlorophyceae, and Euglenophyceae. On the other hand, Perry et al. (1990) found that green algae and diatoms were dominant in summer, while blue green algae were dominant in autumn. ...
In semi-intensive aquaculture systems, cultured fish can rely on natural food, produced through fertilization, up to certain size. Beyond this size, supplemental diet becomes imperative to sustain optimum fish growth. The application of supplemental diet to fish ponds should be optimized. In this regard, the present study was carried out to examine the relative importance of top-down (fish predation) and bottom-up (nutrient addition) control to phytoplankton dynamics in earthen fish ponds receiving different rates of supplemental feed for 19 weeks, and polycultured with Nile tilapia, Oreochromis niloticus (L.); common carp, Cyprinus carpio (L.); and silver carp, Hypophthalmichthys molitrix (V.). Ten earthen ponds (0.1 ha each) were used in this study. Each pond was stocked with 1,000 Nile tilapia (13.7±1.2 g), 200 common carp (10.7±1.7 g) and 1,000 silver carp (1.8±0.3 g). The supplemental diet was provided to the ponds at a daily rate of 0.0% (control), 0.5%, 1%, 3%, and 5% of fish biomass. Water quality analyses revealed that water temperature, pH, free ammonia, and water conductivity were not significantly affected by feeding rate, while dissolved oxygen, orthophosphate, and nitrate levels were significantly (P < 0.05) increased with increasing feeding levels. Average Secchi disk reading was significantly (P < 0.05) lower at higher feeding rates. Chlorophyll a content and phytoplankton and zooplankton densities were also directly correlated to feeding rate up to 5%. The maximum growth of Nile tilapia and common carp was obtained at feeding rate of 3% and 5%, respectively, while the maximum growth of silver carp was obtained at 0.5% feeding rate. The best total fish production was obtained at 3% feeding rate. This study suggested that the optimum feeding rate for Nile tilapia, common carp, and silver carp reared in a polyculture system, in earthen ponds is 3% of fish biomass.
... Several studies have shown that algal communities during pre-disturbance periods with short residence time are generally dominated by diatoms. Cyanobacterial communities often dominate in post-distrurbance periods with variations in flushing rates (Stockner and Benson, 1967; Peterson and Stevenson, 1989; Perry et al., 1990). Additionally, changes in phytoplankton diversity can be dependent on the availability of growth limiting resources. ...
With the increasing rate of species extinctions following anthropogenic perturbation, there is a growing interest in biodiversity research. Although productivity and species richness relationships have been tested and applied in contemporary aquatic ecological studies, none have been applied to paleoecology with contrasting trophic states. The present study explores the applicability of a contemporary production and species richness relationship in high-resolution paleoecological records with low, intermediate and mid to high productive aquatic systems. Results from our study reveal that diatom species richness was positively correlated in low to intermediate productive lakes. In contrast, the relationship was hump shaped (unimodal) in a mid to high productive system concurrent with the species diversity analyses. Contrasting relationships between diatom species richness and stable isotope records (δ 13 C and δ 15 N) suggested that the nutrient biogeochemical cycle might play an important role in controlling species richness. From fossil pigment records we show that the variations in algal functional group signatures were highest in intermediate state. Collectively, these results suggest that the hump shaped (unimodal) relationship between diatom species richness and production might be limited to high productive systems with maximum richness and diversity in intermediate states, which is also supported in contemporary studies. Moreover, fossil pigment records as proxies for algal functional groups reveal that in a mid to high productive system with intense watershed scale disturbances, community composition of algal functional groups declined favoring certain diatoms. Our results demonstrate the applicability of production and diversity relationship theory in paleo-perspective and that recent watershed scale land use changes might affect the species diversity in aquatic systems.
... A residence time of -3 days may be critical. The shortest onset of growth was found after 3-4 days (Perry et al., 1990; Basu and Pick, 1996). This threshold is in agreement with the generation times of rotifers (Walz, 1987). ...
The Neuendorfer See is a shallow lake through which the River Spree flows. In the lake, abundances of zooplankton (mainly
rotifers) and phytoplankton increased exponentially over the flowing stretch between the inflow and the outflow of the river.
Increase in space is enhanced by increased residence time in the lake. Sensitivity of plankton development on residence times
of >8 days weakened at longer residence times. This pattern holds for all zooplankton species. Rates of change in chlorophyll
and rotifers (after correction for temperature) are first enhanced, then are decreased at longer residence times. Concentrations
of dissolved inorganic nutrients [Si, soluble reactive phosphorus (SRP) and NO3−] and the N/P ratio diminished with increasing residence time. The plankton dynamics in the lake were dependent on discharge
and the lake behaved as a ‘plug flow tubular reactor’ with minor longitudinal mixing. This was not different from the transportation
in large rivers.
In this research, we investigated the possible consequences of the 2012–2014 drought in Southeastern Brazil on growing phytoplankton in a eutrophic reservoir. Weather has direct influence to phytoplankton communities and, consequently, underwater light climate which drives important processes in aquatic systems. Absorption coefficient of phytoplankton pigment (a φ) and chlorophyll-a (Chl-a) concentration were determined in laboratory in order to analyze the interference of phytoplankton biomass over light. In addition, a historical monthly rainfall series in the reservoir was analyzed. Results showed clearly the strong drought effect over the monthly useful volume and flow rate. Both of them play important roles to water column mixing and retention time which increase the nutrients availability in the system and phytoplankton biomass. Chl-a concentration and a phy values were extremely high [maximum Chl-a of 797.8 mg m−3 and a φ(440) of almost 6 m−1 in October]. So, more attention should be paid to water quality in long episodes of drought as occurred from 2012 to 2014.
This study attempts to describe changes in plankton biomass (including bacteria, phytoplankton, ciliates, rotifers, and crustaceans) in the semi-arid, hypertrophic, freshwater wetland, Las Tablas de Daimiel National Park (central Spain), in relation to water inflow. An inter-annual comparison of 1996 and 1997, with contrasting rainfall, reveals that inflows in the form of flooding act as a bottom-up structuring force on total plankton biomass. However, the responses of plankton biomass to flooding were different in strength between the two years, which can be attributed to shifts in plankton community structure. Crustacean zooplankton conditioned total plankton biomass in 1996, based on the relationship between the high individual biomass and community development. Crustaceans decreased in 1997, while bacteria, phytoplankton and rotifers increased. The quantitative increase of the latter groups resulted in a higher total plankton biomass in 1997. The key position of crustaceans in the wetland plankton is also reflected in their capability for exerting significant topdown control, which was clearly evident in 1996 but weaker in 1997, based on their numerical reduction. Statistical analyses provide evidence that the decline of trophic interactions in 1997 is related to the strength of flooding in that year, thereby highlighting the significance of the disruptive action of physical disturbance on biotic interactions in the plankton. Flooding and areal inundation were also shown to be significant for spatial heterogeneity. In 1996, site-specific development took place in the absence of prolonged flooding effects, resulting in high spatial heterogeneity. In 1997, however, remarkable homogenization of plankton biomass occurred along the major water flow path. Thus, wetland landscape heterogeneity depends on inflows which condition areal inundation. This, in turn, influences plankton dynamics.
This study was conducted to evaluate the effect of polyculture of
different stocking ratios of Nile tilapia (NT), Oreochromis niloticus,
common carp (CC), Cyprinus carpio and silver carp (SC),
Hypophthalmichthys molitrix reared in earthen pond on growth
performance, total production and water ecosystem. The investigated fish
species were polycultured at five groups (G1-G5) with ratios of
(G1)50:25:25 %, (G 2) 60:20:20 %, (G 3) 70:15:15 %, (G 4)80:10:10 %
and (G5) 90:5:5 % for NT: CC: SC respectively. Fish were stocked at a
joint density of 2 fish /m2 i.e. 2000 fish per pond (1000-m2) in all groups.
Organic and inorganic fertilizers were applied to each pond by the same
way every two weeks, with 15 kg chicken manure, 7.5 kg monosuperphosphate
(15.5% P2O5) and 2.5 kg urea (46.5% N) and no
supplementary diet was added. Every month, 10% of total fish in each
pond were sampled, and the individual weights were recorded. Water
samples were taken every 2 weeks from each pond and tabulated monthly
to determine the different water variables. After 150-days, ponds were
drained and the grown fish were harvested. It was found that growth
parameters of reared fish including final weight, final length, weight
gain, daily weight gain, specific growth rate and relative growth rate
decreased significantly (P<0.05) with the increase of their densities. K
factor for NT, CC and SC was not significantly affected by fish stocking
ratios. Nile tilapia production increased significantly, while common carp
and silver carp production decreased significantly from G1 to G5. The
highest total fish production was obtained at G4, whereas the lowest one
was obtained at G5. All water parameters were not affected by different
stocking groups except electric conductivity and total hardness which
increased with the increasing of carp fish density (common carp and
silver carp). The proximate analysis of fish body (moisture, protein, ash,
and lipids contents) of reared fish showed that there were no significant
differences among all stocking groups for the three fish species.
Small pilot ponds in a glasshouse at the Scottish Agricultural College (Auchincruive) were used to investigate the effects of changing C:N:P loading rate and retention time on pond performance as measured by nutrient removal and dry matter biomass. One experiment investigated ponds operated at two C:N:P ratios: low (9:7:1) and high (104:10:1) and two retention times (4 and 7 days θ. Increasing retention time from 4 to 7 days increased the concentration of total (dry matter) and algal (chlorophyll a) biomass and the degree of nitrification. It also increased removal of phosphorus, but had no effect on nitrogen or COD removal. Cyanobacteria predominated in ponds operated at both 4 and 7 days, and the density of cyanobacteria increased with increased retention time. Nitrogen removal was independent of C:N:P ratio; indeed the lower C:N:P ratio favoured increased nitrification. A high C:N:P ratio increased phosphorus and COD removal and increased the concentration of algal biomass (chlorophyll a), but had little effect on total biomass (dry matter). A second experiment varied COD loading rate (600, 350 and 100 kg COD ha^-1 d^-1) while maintaining a constant retention time (either 5 or 7 days θ). Species composition was independent of retention time. The longer retention time increased both total and algal biomass concentration and also percentage of nitrogen removed. Nitrification was independent of retention time. Increasing loading rate increased dry matter production and resulted in a predominance of cyanobacteria over Chlorophyceae. Increased loading rate was related to increase in nitrogen removal, however more complete nitrification occurred at low COD loading rates. Phosphorus removal in the pond with 5-day (θ) remained constant independent of loading rate, but in the pond with 7-day θ phosphorus removal increased with increased COD loading. COD removal was independent of both retention time and loading rate.
Properties of aquatic ecosystems have recently been considered in a landscape context where lakes in a geographic area are examined to identify common and long-term behavior patterns for one or more variables. Identifying such temporally coherent features should permit generalizations about lake behavior in specific regions and therefore, predictive models based upon such information should have broad applicability within a regional landscape. We considered the temporal coherence of a number of physical, chemical, and biological features of two southwestern reservoirs that differed in age, watersheds, and trophic status to identify common landscape-level predictors of behavior. We found synchronous behavior (temporal coherence) associated with particulate nutrient dynamics (organic carbon, nitrogen and phosphate (PP)), dissolved factors that force plankton dynamics (total dissolved phosphate, reactive phosphate and reactive silicate (SRSi), and with nutrient ratios used as indices of nutrient limitation in the plankton (TDN:TDP, C:P, and N:P). Algal parameters related to biomass (chlorophyll and Simpson's diversity index) did not vary coherently but algal genus richness and bacterial abundance did. Temperature was identified as a forcing function explaining synchronous variability in all cases except SRSi, PP, C:P, N:P, bacteria, and richness. The two systems, although managed for different purposes, behaved similarly with respect to several commonly measured limnological features, most notably, those involving phosphorus. We conclude that it may be possible to use such analysis to establish reference conditions for reservoirs in a given geographic region.
Selective withdrawal through the surface outlet was employed in Eau Galle Reservoir to reduce phytoplankton populations by 1) strengthening thermal stability, thereby decreasing vertical entrainment of hypolimnetic phosphorus (P); and 2) increasing epilimnetic flushing rate and discharge of algae. In spite of substantial release of sediment P over the growing season, epilimnentic P concentrations were overwhelming dominated by external sources, and thus insensitive to changes in withdrawal depth. Nor did surface withdrawal increase flushing rate sufficiently to affect phytoplankton biomass. In one year, an increase in thermal stability, due in part to surface withdrawal, permitted the development of a metalimnetic chlorophyll maximum in a summer that also experienced relatively low populations of ‘nuisance’ cyanophytes, and can be regarded as a positive effect of the change in operations.
East Sidney Lake, a small, eutrophic bottom release impoundment in NY, has undergone artificial circulation for three seasons. The artificial circulation system resulted in an overall reduction in the physical stability of the water column, making the lake subject to alternating periods of weak chemical stratification and mixing. Phytoplankton community succession exhibited a high degree of regularity from year to year, culminating in mid summer dominance by heterocystous cyanophytes in all years. Changes in the physical structure of the water column, with attendant changes in Z
eu
:Z
mix
, were not important determinants of phytoplankton community makeup in East Sidney Lake. Seasonal patterns and community characteristics were not affected by artificially induced alterations in stability, but instead were most sensitive to surface temperatures, flushing rate and TN:TP. The timing of cyanophyte blooms was not affected by artificial circulation, nor was maximum seasonal phytoplankton biomass reduced.
Rotifers were sampled at monthly intervals for a year at four monitoring stations in Rapel Reservoir (a hydroelectric impoundment) in Central Chile (34°02′S; 71°35′W). Fifteen species were identified, but only Keratella cochlearis was consistently found at each station, it usually was the most abundant (> 50% of total rotifers). Marked differences were found among sites; stations I and 2, those nearest to the dam, showed greatest rotifer densities in spring and autumn. Station 4, that nearest to the inflowing rivers, had its highest rotifer abundance in summer. Station 8 had the highest mean density but the least marked seasonal changes in rotifer numbers.
The impoundment water dynamics and the relative locations within the lake (distance from the dam or from the rivers) are suggested as determinants for different rotifer assemblages and, probably, for most other planktonic organisms.
Develops the notion of a 'phycosphere', with examination of: the size and abundance of planktonic bacteria and algae; associated species in the algal microenvironment; endosymbiotic bacteria; inhibition of algal growth by bacteria (eg. by modifying the environment, by lysis, by competing for limiting nutrients and by other forms of inhibition); stimulation of algal growth by bacteria (eg. by nutrient regeneration, vitamin production, and other stimulatory products); inhibition of bacterial growth by algae (eg. by production of antibiotics and alteration of the macroenvironment); and stimulation of bacteria by algae (eg. by decomposition, extracellular release, and growth of enteric and pathogenic organisms in algal organic matter). The appropriateness of considering ecological succession in the phycosphere is indicated.-P.J.Jarvis
The US participation in the OECD Eutrophication Program of having 20 investigators prepare reports on the nutrient load-lake and impoundment response relationships for their respective water bodies. This report presents a critical review of these overall relationships with particular emphasis given to evaluation of the Vollenweider nutrient load-trophic state formulations. This review includes consideration of the nutrient load response relationships for 38 water bodies, or parts of water bodies, located throughout the US, with the preponderance located in the northern half of the US. It has been found that the Vollenweider nutrient load relationship involving water body mean depth, hydraulic residence time and phosphorus load correlates well with the trophic states assigned by the US OECD eutrophication study investigators. A good correlation has also been found between phosphorus loading, normalized as to hydraulic residence time and mean depth, and the average chlorophyll and water clarity (as measured by Secchi depth) for the US OECD water bodies. In general, phosphorus and nitrogen loads to US OECD water bodies were within a factor of + two of the loads predicted on the basis of average nutrient concentrations within the water bodies and on the land use patterns within the water body watersheds. Generalized nutrient export coefficients have been developed in this study, enabling estimates of nutrient loads to be made on the basis of land use patterns within the watershed. The relationships developed in this study can be used to predict the improvement in water quality that will result from a change in the phosphorus load to a water body for which phosphorus is the key chemical element limiting planktonic algal growth. The US OECD water bodies all show approximately the same trophic status when evaluated by several recently-proposed trophic state index systems. A new trophic state index system has been developed in this study which is based on the relationship between the actual phosphorus loading and permissible phosphorus loading as defined in the Vollenweider phosphorus loading and mean depth/hydraulic residence time relationship. This relationship has been modified to enable water quality managers to determine the appropriate phosphorus load for a particular water body in order to yield a certain chlorophyll content from planktonic algae and its corresponding water clarity. It is recommended that these relationships be used as a basis for establishing critical phosphorus loads to lakes and impoundments. This report was submitted in fulfillment of Contract No. R-803356-01-0 and Contract No. R-803356-01-3 under the sponsorship of the U.S. Environmental Protection Agency. Work was completed as of August, 1977. EPA
A considerable development of phyto- and zooplankton occurs seasonally in the Blue Nile at Khartoum. Details of seasonal succession are described from quantitative and qualitative records made chiefly during 1951-53 (zooplankton) and 1955-56 (phytoplankton). They are interpreted in relation to hydrological, physical and chemical characteristics, with some evidence from longitudinal upstream surveys of plankton development. Concentrations of plankton were very low during the annual phase of high flood water, when adverse conditions of rapid flow and high turbidity existed. Subsequent population increase was rapid, particularly by the diatom Melosira granulata and the crustaceans Moina dubia and some Cyclopid Copepods; it was probably favoured by the filling of an upstream reservoir and relatively high concentrations of some plant nutrients. The reduction of nitrate-nitrogen to below 10-20 μ g/l was possibly responsible for the primary check to the increase of Melosira, as in the neighbouring White Nile. Later increase of the blue-green alga Anabaena flos-aquae f. spiroides produced higher population densities, some supersaturation of dissolved oxygen, increase of pH to values of 8· 9 or more, and probably contributed to a depletion of phosphate. A decline of both phyto- and zooplankton occurred about March-April, and a second maximum appeared in May-June before the flood; the environmental control of these events is poorly understood. Both plankton maxima at Khartoum were partly the result of multiplication in flowing river conditions below the reservoir; the first maximum involved a sharp increase of plankton in the seasonally filled reservoir. Quantitative aspects of planktonic growth and production under these two hydrological situations are discussed and contrasted. The importance of the reservoir in enhancing plankton development is supported by evidence from older records. Brief comparison is made with other examples of dense plankton development in the Nile river system, both in reservoirs and in flowing river conditions.
A regression analysis of global data for freshwater phytoplankton production, chlorophyll, and various nutrient parameters revealed the following: A high proportion of the variance in both annual phytoplankton production and mean annual chlorophyll could be explained by annual phosphorus input (loading), once a simple correction for water renewal time was applied. Good relationships were also found between phosphorus loading and mean total phosphorus concentration, and between total phosphorus concentration and chlorophyll. The slope of the regression of total phosphorus on phosphorus loading for stratified lakes was not significantly different from that for unstratified lakes, suggesting that the effect of stratification on phosphorus concentration is insignificant compared to external sources of the element. Nutrient input, which was unavailable in previous analyses, appears to be an important factor in controlling freshwater production. There is some evidence for a correlation between latitude and nutrient input, and it is possible that this may explain the good correlation between latitude and production observed by earlier investigators.
Data for summer chlorophyll and spring total phosphorus concentration were collected from 19 lakes in southern Ontario and combined with data reported in the literature for other North American lakes to produce a regression line that can be used to predict the average summer chlorophyll concentration from a single measurement of phosphorus concentration at spring overturn. This equation is not significantly different from a previously published phosphorus‐chlorophyll relationship derived for a number of Japanese lakes.
Primary production in Marion Lake is inversely related to the rate at which water enters the lake when light intensity is corrected to a standard level. Increased flushing rates reduce the phytoplankton standing crop thereby lowering the total primary productivity in the lake. Thus seasonal variations in rainfall in southwestern British Columbia exert an appreciable influence on the annual productivity pattern of the lake’s phytoplankton.
Lake water artificially enclosed within small areas of the lake produced algal blooms while phytoplankton standing crop in the rest of the lake remained low. Nannoplankton appear to have a selective advantage over larger, more slowly reproducing forms in Marion Lake. The production: biomass ratio for lake phytoplankton was used as an indication of the general type of limiting factor affecting the instantaneous rate of productivity in the lake.
Water renewal may influence reservoir zooplankton communities through the mechanisms of dilution, transport (selective removal or addition), or through localized modifications of limnological conditions (e.g., light penetration, food quality, temperature) which then provide the setting for alteration of zooplankton community structure. An inverse relationship between reproduction in cladoceran zooplankton and water renewal time was found for six reservoirs sampled during summer 1980. This relationship suggests a strategic response in resource allocation by cladoaerans to dilution effects associated with water renewal. However, analysis of variation in cladoceran demography at different sites within each of the reservoirs and over a four-month period at a single site in one reservoir demonstrated that repoductive variation could be explained by spatial or temporal variation in limnological conditions and independently of transport or dilution processes associated with water renewal.
The zooplankton of the Blue Nile overcomes the adverse conditions of the flood by entering into a state of diapause. Resting stages were found in the river bottom, flowing water and rain pools. They were blown to different localities by wind and can withstand long periods of desiccation. Some species of zooplankton go into diapause more than once a year, notably during their seasonal peaks of abundance. Release from diapause occurred in the temperature range 20–30°C and was facilitated by longer photoperiods and decreased concentrations of suspended silt. Various species of zooplankton were induced in facultative diapause when stored in complete darkness.
We examined the abundance and heterotrophic uptake of bacteria attached to particulate matter suspended in five coastal ponds and two marshes near Woods Hole, Mass. Although the number of particle-bound bacteria was low (<10%), these bacteria incorporated a large proportion (>40%) of [ ¹⁴ C]glucose and [ ¹⁴ C]glutamate in selected aquatic systems. The uptake per cell was significantly higher for epibacteria than for unattached bacteria in all systems. Two groups of the aquatic environments sampled were statistically different in the contribution made by particle-bound bacteria to total bacterial abundance and to total assimilation of [ ¹⁴ C]glucose and [ ¹⁴ C]glutamate. Particle-bound bacteria were more important in those waters with a high particle concentration and not flushed regularly by tides than in waters with a low particle concentration and flushed regularly.
During 1981 the seasonal growth and community composition of phytoplankton were investigated at six sampling stations in Eau Galle reservoir, a shallow eutrophic basin located in central Wisconsin, U.S.A. Eau Galle was strongly dominated by diatoms (spring and fall), and co-dominated by cyanophytes and dinoflagellates (summer). Three species (Stephanodiscus hantzschii Grun., Aphanizomenon flos- aquae (L.) Ralfs, and Ceratium hirundinella (O.F.M.) Schrank) collectively contributed about 50% of total annual phytoplankton biomass. Phytoplankton response was quite similar at open water sampling stations, but differed at a station in the littoral zone and at another located near the mouth of the primary inflowing river. Depressed epilimnetic silica concentrations occurred during spring and fall periods of diatom growth. The development of nitrogen-fixing cyanophyte populations during the summer reflected reduced dissolved inorganic nitrogen availability. Midsummer mixing events reduced water column stability. Shifts in the phytoplankton species composition of Eau Galle appeared to occur in response to major changes in water column stability.
1. This review considers the periodic cycles of species dominance in a wide selection of temperate lakes. By ascribing individual species to assemblages, a high incidence of similarity among periodic cycles is demonstrated. Reference to lakes at high and low latitudes, as well as to rivers, shows conformity to parts of the same broad patterns.
2. The role of population dynamics in shaping community structure is emphasized. Two types of change are recognized: autogenic, undirectional subsequences (successions), regulated by specific responses to critically changing resource-ratio gradients; and allogenic changes, regulated by variability in the physical environment.
3. Analysis of the responses of representative species to allogenic change permits further grouping of the assemblages. These groupings coincide with clear morphological distinctions among the same phytoplankton species according to their unit sizes and surface area/volume ratios.
4. It is argued that these properties condition the physiological responses of algae to seasonal variations in temperature, mixing and exposure to the underwater light field. The responses are compounded by relative resistances to loss processes (sinking, grazing), by short-term photosynthetic adaptation and vertical migratory behaviour.
5. Graphical summaries are presented that relate the morphologically-, physiologically- and behaviourally-mediated responses to a hierarchy of physical, chemical and biotic environmental variables. Phytoplankton periodicity is the outcome of these interactions.
1. The diel vertical distribution and abundance of zooplankton in the Red River arm of Lake Texoma, Oklahoma‐Texas, U.S.A., were examined between 25 January and 26 June 1982.
2. During periods of low river inflow, zooplankton vertical patchiness was related to wind stress. Zooplankton did not maintain distinct vertical patches under strong mixing.
3. In mid May heavy rainfall in the drainage basin increased discharge from the Red River and reduced water retention time in the reservoir. The Red River water mass entered the lake as a turbid, surface overflow plume. During this period of flooding most zooplankton populations declined and the distributions of remaining individuals deepened. Greatest population losses occurred between 0 and 7m, depths where most zooplankton had been concentrated prior to the flood.
4. A model of population dynamics based on depth specific rates of water exchange between the lake and the Red River, estimated from conductivity changes through time, accounted for the general pattern of change in zooplankton abundance and vertical dispersion.
Zooplankton community structure was examined at five stations in Normandy Reservoir, Tennessee, on six dates from 11 July to 15 September 1980. Four physical and chemical parameters at three depths at each station were used to discriminate statistically among areas of the reservoir over time; a similar analysis based on nine taxonomic and ecological categories of zooplankton was also completed. Each of the two multi-variate analyses provided a matrix of similarities among station-times (n = 30) in the reservoir. The two similarity matrices were compared by the Mantel test and were found to be not significantly concordant, suggesting that physical-chemical variation among areas in the reservoir during the summer months was not precisely reflected by zooplankton community structure.
The lack of congruence between physically- and chemically-determined reservoir structure and structure implied by zooplankton taxa or functional groups was also observed in the results of a random-effects-model ANOVA of physical and chemical parameters and zooplankton densities. ANOVA of zooplankton densities revealed that spatial variation was generally greater than temporal variation, although most of the spatial variation was ephemeral (station-time interaction) rather than fixed (station effects). An ANOVA of physical and chemical variables revealed considerable fixed spatial variation over the same time scale.
Various methods for the estimation of populations of algae and other small freshwater organisms are described. A method of counting is described in detail. It is basically that of Utermhl and uses an inverted microscope.If the organisms are randomly distributed, a single count is sufficient to obtain an estimate of their abundance and confidence limits for this estimate, even if pipetting, dilution or concentration are involved.The errors in the actual counting and in converting colony counts to cell numbers are considered and found to be small relative to the random sampling error.Data are also given for a variant of Utermhl''s method using a normal microscope and for a method of using a haemocytometer for the larger plankton algae.
Dilution water, low in macronutrients, was added to Moses Lake on three occasions in 1977 and once in 1978 during the spring-summer period. The addition resulted in reducing the annual average inflow concentration of phosphorus from about 130–140 μg l−1 to 100 μg l−1. The water exchange rate in Parker Horn, which is 8% of the lake volume, increased from about 1% day−1 normally to 7 and 11% day−1 for the May–September period in 1977 and 1978, respectively. Lake water was displaced at a predictable rate in the whole lake as well as the areas proximal to the input, as verified by specific conductance.Improvements in lake quality, compared to values from 1969–70, were rather good with greater reductions in algal biomass occurring than might have been expected to result from the less impressive reductions in total P content. Chlorophyll a decreased by about 60–80% and total P decreased by about 50–60%, depending on the area of the lake. However, Chl a averaged only 15 μg l−1 during May–September 1978, while total P was rather high at 70–80 μg l−1. The fraction of the phytoplankton composed by blue-green algae decreased from 96% in 1970 to 68% in 1977–78. The cause for the effect on biomass and species composition is unknown, but may be related to dilution of blue-green excretory products.A dilution water input of about 6 m3 s−1 continuously during April–September would require 20% less total water and should provide adequate control of eutrophication in at least 30% of the lake volume proximal to the input and Parker Horn. That would provide an exchange rate of 5% day−1 for Parker Horn and should achieve lake water residuals by midsummer of ⩽50%. Two additional inputs to the lake are also proposed as two more phases in the restoration project.
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The seasonal succession of the phytoplankton of a small reservoir (Guelph Lake, Ontario) in the spring-summer of 1982 was compared to that in 1981. Mixing of the deeper waters occurred several times throughout the summer in 1982 but not in 1981. The water at 10 m became anoxic for only 2 weeks in late July in 1982. In contrast, in 1981, the water at 10 m became anoxic at the beginning of July and remained so until mid-September. The phytoplankton dynamics observed in 1982 did not follow the typical progression from spring diatoms to summer species adapted to survive under stratified conditions, as in 1981. Diatoms were present throughout the summer in higher amounts in 1982 than in 1981. The most obvious difference in the two summers was the much greater abundance of Aphanizomenon flow-aquae in 1982. Other blue-green algae including Microcystis aeruginosa, Gomphosphasria lacustris , and Lyngbya birgei appeared earlier on in 1982, but did not immediately increase in abundance as in 1981. In 1982, rates of phytoplankton community change were low in May and June and increases were observed in mid-July, early August, late August and late September. In contrast, in 1981, the rate of community change increased in late May, mid-June, early July and late July and remained low throughout August and September.
1969: Some effrcts of lake renewd on pliyt,oplankton productivity and species coin-position.--limnol
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DICKMAN, M.. 1969: Some effrcts of lake renewd on pliyt,oplankton productivity and species coin-position.--limnol. Ocemogr. 14: 660-666.
Ameriran Water U'orks A4ssociat,ion. ;tnd WiLtvr Pollution Control Federation). lYXf : Stondard Methods for t h c Esa.minat,ion of Wat.er and Wastewater. 15t.h Sea-sonal growth and community composition of phyt
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The phospliorus-cliloropliyll rclationship in 1akrs
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Water Resources Data West Virginia, Water Year 1985
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Portion) OECD Eutrophication Project: Nutrient Loading-Lake Response Relationships and Trophic State Indices
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SAS User's Guide.-Cary, North Carolina
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SAS User's Guide.-Cary North Carolina
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Studies on redox potential of marine sediments
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Geological Survey and West Virginia Geological and Economic Survey Morgantown W
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Plankton in a rapidly flushed impoundment: spatial distribution, population dynamics and community structure
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