The Spatial and Temporal Distribution of Epipelic Algae in a Shallow Eutrophic Prairie-parkland Lake,Alberta, Canada

Investigations were conducted upon the epipelic algal community of a shallow eutrophic lake in central Alberta, Canada. The lake was Hastings Lake (longitudes 112° 50′ and 113° 00′ W; latitudes 53° 15′ and 53° 50′ N). The epipelic algae displayed both spatial and temporal distributions for species composition, standing crop as well as productivity. In situ cross incubation experiments showed the potential photosynthetic viability of epipelic algae living below the 1% irradiance level.     

PERIODICITY OF EPIPELIC UNICELLULAR VOLVOCALES (CHLOROPHYCEAE) IN A SHALLOW ACID POOL1

The occurrence, periodicity and growth of twenty species of unicellular Volvocales on sediments in an acidic pool are described. Minimum populations were recorded in winter, but during the rest of the year standing crops fluctuated rapidly. The greatest species diversity and primary productivity occurred in late spring-early summer and in autumn, when maximum numbers of Chlamydomonas spp. and Chloromonas spp. increased exponentially on the sediments. The chlamydomonads were more numerous in the epipelon than other major algal components such as diatoms, euglenoids, bluegreen algae and desmids. Growth of the chlamydomonad population occurred after the period of maximum diatom standing crop. Evidence shows that rates of primary production were greater in late spring and late summer when species diversity and standing crop or apparent growth rates of unicellular Volvocales were high. Thus these algae which are normally neglected may be more important in primary productivity than previously believed since they grow during periods when larger algae are scarce. Analysis of the data using the multivariate technique of Reciprocal Averaging confirmed seasonal periodicity in this community of epipelic flagellates. It also identified species with distinctive ecological requirements. A relationship between the bicarbonate-alkalinity of the overlying water and the chlamydomonad population was demonstrated by ordination analysis.     

Seasonal succession of algae in a eutrophic stream in Southern England

The epipelic and epilithic algal communities in a small eutrophic stream situated in southern England expanded rapidly during March of both 1973 and 1974 primarily in response to changing light conditions. Although numbers varied greatly during the summer, these fluctuations were probably not due to nutrient, temperature or light conditions. High rates of disappearance of algae from the substrate were correlated with flooding, a deterioration of attachment characteristics and high metabolic rates. The episammic algal community consisted of only a few species, all of which showed maximum development during the summer. Although the well developed attachment mechanism and small size of the species undoubtedly aid in their ability to colonize sand grains, each species must be able to withstand frequent burial in the bottom deposits. Although temperature was probably an important factor controlling the number of epiphytes associated with Cladophora glomerata, light seemed to be of relatively less importance. Large numbers of isopods, amphipods and copepods occurred in the stream but their grazing seemed to have had little effect of the standing crop of the algae.     

Observations on standing crops of epipelic and epipsammic algal communities in Shear Water,Wilts

Methods of estimating the standing crops of epipsammic diatoms have been evaluated and compared with those used for epipelic algal crops.

Good correlations between chlorophyll a content and cell counts were obtained for epipelic populations, but because of the presence of large numbers of decaying cells, inseparable from living cells, such correlation was not obtained with epipsammic algae, even after correction of the pigment estimates for the presence of pheophytin a. The standing crop of epipsammic algae was at all times greater than that of epipelic algae at the same sampling station, and this was attributed to the differential effects of sediment disturbance by burrowing animals and water movements.     

Standing crops and primary productivity of the epipelon of two small ponds in North Somerset,U. K.

Summary The primary productivity and the standing crop of the epipelic algal communities in two small ponds of contrasting nutrient status were measured over a 2 year period. Standing crops reflected the richer nutrient status of the eutrophic Abbot's Pond compared with the oligotrophic Priddy Pool as did the productivity results when the same depth category in both ponds was examined. Production resulted from an interrelationship among light intensity, standing crop size and other variable environmental factors in both pools, however light in Abbot's Pond appeared to be the most important factor in limiting standing crop size and production in the deeper depth categories.     

Atyid shrimps (Decapoda: Atyidae) influence the spatial heterogeneity of algal communities over different scales in tropical montane streams, Puerto Rico

1. Atyid (Decapoda: Atyidae) shrimps influence the distribution of algal communities over different scales in tropical montane streams of Puerto Rico. Within pools of an atyid-dominated stream, atyid shrimps enhanced patchiness in algal communities along the depth gradient. Algal bands occurred in shallow pool margins where atyids did not forage (< 3 cm below water surface), with significantly greater standing crop, taxon richness, and structural complexity than deeper areas. In deeper water, atyids reduced small-scale patchiness in algal community composition and maintained a low-growing understorey turf dominated by sessile diatoms (Bacillariophyta) and, sometimes, closely cropped, filamentous blue-greens (Cyanophyta).
2. Among pools of the atyid-dominated stream, atyids interacted with light to determine algal patchiness between stream margins and deeper areas. In sunny pools, algal standing crop was 140-fold greater in pool margins than in deeper areas where atyids foraged. In shaded pools, however, standing crop in pool margins was only 5-fold greater than in deeper areas. Effects of light on algal standing crop were greater outside atyid foraging areas than within, indicating that shrimp grazing overrides the positive effects of light.
3. In contrast to the atyid-dominated stream, algal communities in an atyid-poor stream were characterized by a high biomass of loosely attached epipelic diatoms and no depth zonation. Interstream rock and shrimp transplant experiments indicated that atyids significantly reduced algal standing crop and altered community composition on rocks from atyid-poor streams within 24 h. Results support the hypothesis that atyid shrimps play a major role in determining observed interstream differences in algal communities.     

Atyid shrimps (Decapoda: Atyidae) influence the spatial heterogeneity of algal communities over different scales in tropical montane streams, Puerto Rico

1. Atyid (Decapoda: Atyidae) shrimps influence the distribution of algal communities over different scales in tropical montane streams of Puerto Rico. Within pools of an atyid-dominated stream, atyid shrimps enhanced patchiness in algal communities along the depth gradient. Algal bands occurred in shallow pool margins where atyids did not forage (< 3 cm below water surface), with significantly greater standing crop, taxon richness, and structural complexity than deeper areas. In deeper water, atyids reduced small-scale patchiness in algal community composition and maintained a low-growing understorey turf dominated by sessile diatoms (Bacillariophyta) and, sometimes, closely cropped, filamentous blue-greens (Cyanophyta).
2. Among pools of the atyid-dominated stream, atyids interacted with light to determine algal patchiness between stream margins and deeper areas. In sunny pools, algal standing crop was 140-fold greater in pool margins than in deeper areas where atyids foraged. In shaded pools, however, standing crop in pool margins was only 5-fold greater than in deeper areas. Effects of light on algal standing crop were greater outside atyid foraging areas than within, indicating that shrimp grazing overrides the positive effects of light.
3. In contrast to the atyid-dominated stream, algal communities in an atyid-poor stream were characterized by a high biomass of loosely attached epipelic diatoms and no depth zonation. Interstream rock and shrimp transplant experiments indicated that atyids significantly reduced algal standing crop and altered community composition on rocks from atyid-poor streams within 24 h. Results support the hypothesis that atyid shrimps play a major role in determining observed interstream differences in algal communities.     

ALGAE OF TWO SOMERSETSHIRE POOLS STANDING CROPS OF PHYTOPLANKTON AND EPIPELIC ALGAE AS MEASURED BY CELL NUMBERS AND CHLOROPHYLL A

Standing crops measured as cell numbers and as chlorophyll a content of phytoplankton and epipelic algal communities (those free-living on sediment surfaces) in 2 small water bodies of contrasted nutrient status were measured for 27 months. Mean yearly crops, on an areal basis, of phytoplankton were 4–13.4 times greater than those of epipelic algae in the nutrient-rich pool, but were only 0.65–1.8 times as great in the nutrient-poor pool, which, however, was shallower than the rich pool. The role of cells < 5 μ, in diameter in the composition of standing crops was minor. Effects of phytoplankton in limiting growth of epipelic algae by light attenuation are shown. Compilation of available data shows a direct relationship between epipelic algal crops in various water bodies and nutrient-status of the ambient water, similar to that already established for phytoplankton.     

Species composition and biomass of an epipelic algal community in a subarctic lake before and during lake fertilization

The species composition, biomass (measured as algal volumes) and chlorophyll concentration of epipelic algae was studies before (1977) and during (1978–1979) fertilization with phosphorus and nitrogen of Lake Gunillajaure, a small subarctic lake in northern Sweden.
The epipelic biomass, dominated by Cyanophyceae and Bacillariophyceae, was high (5.6–20.1 cm³ m⁻²) at all depths in the lake with the highest values in the hypolimnion (8–13.7 m). Calculated over mean depth it was 20 times higher than that of the phytoplankton. There was no significant increase in biomass during fertilization and neither did the species composition change. The chlorophyll concentration on the other hand were significantly higher in late 1978 and in 1979 which was probably an effect of the declining light climate caused by a large phytoplankton development in the lake. Constant seasonal biomass and species composition indicate a perennial epipelic community in this lake.     

PATTERNS OF EPIPELIC ALGAL DISTRIBUTION IN AN ACIDIC ADIRONDACK LAKE1

The biovolume and species composition of epipelic algae along sediment depth gradients were sampled seasonally in an acidic oligotrophic lake in the Adirondack Park in New York State. The epipelic algal community of Woods Lake (Herkimer Co., NY) was dominated by diatoms and cyanobacteria. Distinct depth zonation patterns of community composition were evident. Total algal biovolume increased with depth due to a dense cyanobacterial mat on the sediments in deeper water (5–8 m). This mat was dominated by a single species of cyanobacteria, Hapalosiphon pumilus (Kütz.) Kirchner, which accounted for the late summer maximum in total biovolume at 7 m. The shallower (1–4 m) epipelic communities were dominated by diatoms, which showed a spring maximum in total biovolume and were dominated by Fragilaria acidobiontica Charles, Navicula tenuicephala Hust. and N. subtilissima Cl.     

SEASONAL,SUCCESSION OF ALGAE IN RIVERS. I. EXAMPLES FROM THE AVON,A LARGE SLOW-FLOWING RIVER1

The epipelic, epilithic and epiphytic algae in a large slow-flowing river (the Avon) situated in southern England usually exhibited a pronounced bloom during early spring probably in response, to increasing daylength. Although floods caused a reduction in the standing crop of most communities both through scouring action and possibly long-term alteration of microhabitat, they also seemed essential for the renovation of sediment and, rock substrates after periods of rapid algal growth. Because of the attachment characteristics of the predominant epiphytic species, the community attached to Cladophora remained relatively unaffected by flooding. Water velocity may have been important in determining the species composition of some communities, particularly the epiphytic associations. Nutrients probably seldom limited development, but during part of the summer competition with planktonic diatoms for silicon appeared to limit attached algae. During the summer, large scale detachment (which greatly reduced algal density) apparently correlates with a high photosynthetic rate. Algal, numbers in the plankton occasionally decreased in response to a loss of buoyancy of the predominant species.     

Effects of sediment resuspension on phytoplankton production: teasing apart the influences of light, nutrients and algal entrainment

1. Wind‐induced sediment resuspension can affect planktonic primary productivity by influencing light penetration and nutrient availability, and by contributing meroplankton (algae resuspended from the lake bed) to the water column. We established relationships between sediment resuspension, light and nutrient availability to phytoplankton in a shallow lake on four occasions. 2. The effects of additions of surficial sediments and nutrients on the productivity of phytoplankton communities were measured in 300 mL gas‐tight bottles attached to rotating plankton wheels and exposed to a light gradient, in 24 h incubations at in situ temperatures. 3. While sediment resuspension always increased primary productivity, resuspension released phytoplankton from nutrient limitation in only two of the four experiments because the amount of available nitrogen and phosphorus entrained from the sediments was small compared with typical baseline levels in the water column. In contrast, chlorophyll a entrainment was substantial compared with baseline water column concentrations and the contribution of meroplankton to primary production was important at times, especially when seasonal irradiance in the lake was high. 4. Comparison of the in situ light climate with the threshold of light‐limitation of the phytoplankton indicated that phytoplankton in the lake were only likely to be light‐limited at times of extreme turbidity (e.g. >200 nephelometric turbidity units), particularly when these occur in winter. Therefore, resuspension influenced phytoplankton production mainly via effects on available nutrients and by entraining algae. The importance of each of these varied in time. 5. The partitioning of primary productivity between the water column and sediments in shallow lakes greatly influences the outcome of resuspension events for water column primary productivity.     

太湖湖岸带浮游植物初级生产力特征及影响因素

利用高频溶解氧监测,估算了太湖梅梁湾湖岸带浮游植物初级生产力的高频变化特征。结合同步气象监测及浮游植物、浮游动物和营养盐的周年逐周观测数据,分析了气象和环境条件对富营养化湖泊浮游植物初级生产力的影响。结果发现,高频溶解氧监测估算的初级生产力变化与浮游藻类生物量的变化一致,能够反映出浮游植物生产力的昼夜变化、季节变化等规律。统计分析表明,气温对太湖这一富营养化湖泊初级生产力影响很大;氮的供给与浮游动物的选择性牧食也是影响浮游植物初级生产力的重要因素。湖岸带的水华堆积过程对初级生产力影响巨大,气象、水文过程又加剧了蓝藻水华初级生产力的变化幅度,反映出富营养化湖泊初级生产力可能存在极大的时空不均一性。研究表明,溶解氧高频监测法估算初级生产力能够捕捉到湖泊初级生产力的快速变化过程,可以用于富营养化湖泊初级生产力监测、蓝藻水华灾害预警中。     

Light,nitrogen, and phosphorus limitation of edaphic algae in a delaware salt marsh

The effects on edaphic algae associated with a pure stand of the cord grass, Spartina alterniflora Loisel of manipulating light intensity and additions of inorganic nitrogen and phosphorus as fertilizers to the marsh surface have been investigated for one year. The standing crop of edaphic algae as measured by chlorophyll a production was limited only by phosphorus supplies during fall and winter, by both phosphorus and nitrogen in spring, and only by nitrogen during the summer. Since the responses were in phase with the seasonal fluctuations in the concentration of nitrogen and phosphorus, it is concluded that the flood tide is the major source of nitrogen and phosphorus compounds for edaphic algal growth. Reduction in the quantity of light reaching the edaphic algae by Spartina cover is always a limiting factor for the standing crop. A gradient in the composition of the algal flora is directly related to light intensity, and indicates that this factor determines the relative contribution of diatoms and filamentous algae to the community. The interaction of light intensity and nutrients in regulating the production of edaphic algae and cord grass on the marsh under study over a yearly cycle has also been investigated.     

Disturbance, resource supply, and food-web architecture in streams

We studied food webs comprising fish, macroinvertebrates, and algae (identified to species or morphospecies) in small streams using a consistent methodology at the same spatial and temporal scales. Our aim was to test a priori hypotheses derived from dynamic-demographic and energetics models concerning the effects of disturbance and resource availability on food-web attributes. The regime of bed disturbance affecting the organisms in the webs was measured in 10 streams. We also derived measures of the supply of resources for animals in the webs in terms of algal primary productivity and detritus standing crop. Both web size and number of links per species were significantly negatively related to mean intensity of bed disturbance. Mean chain length had a significant positive relationship with algal primary productivity but not disturbance. No food-web attribute was related to detritus standing crop.     

Uptake of phosphate and inorganic nitrogen by a sediment-algal system in a subarctic lake

SUMMARY.

• 1 The uptake of phosphate and inorganic nitrogen by sediment and phytoplankton was studied under natural conditions (1977) and during lake fertilization with phosphorus and nitrogen (1978–79) in Lake Gunillajaure, a small, stratified, subarctic lake in northern Sweden. The experiments were performed in situ in plexiglass cylinders, to which additions of nutrients were made, and the uptake followed by consecutive sampling and analysis of the water phase.
• 2 Additions of HgCl₂ to the experimental vessels reduced the phosphate uptake to the sediment to less than 10% and it could therefore be concluded that the sediment uptake was mainly of biological nature.
• 3 Dark assimilation was 30–40% of that in light. Since light clearly stimulated the sediment uptake the epipelic algae were probably responsible.
• 4 The phosphate uptake to the sediment could be described by Michaelis-Menten kinetics and the calculated constants (V_max, ks) were very alike in 1977 and 1978 but appeared to have increased in 1979.
• 5 The sediment uptake of ammonium and nitrate was very slow indrcating that the epipelic algae were not nitrogen starved.
• 6 Even though the epipelic algae had a potential for efficient uptake of phosphorus, the phytoplankton took up 92–96% of the phosphate added to the lake on each fertilization occasion due to the relatively large water volume in the epilimnion in relation to the bottom area available for the epipelic algae.

     

Effects of the discharge of thermal effluent from a power station on Lake Wabamun,Alberta, Canada — The epipelic and epipsamic algal communities

1. The epipelic algal standing crops were increased by the discharge of thermal effluent into Lake Wabamun, particularly in the discharge canal at station (03–04) and 05.
2. The increase in the standing crop size of the epipelon was due to Oscillatoria amoena and O. borneti in the heated area, while the discharge canal provided the inoculum of the algae for the heated area of the lake.
3. At station (03–04) the increased standing crop size was also a function of increased light penetration to the sediment due to the heated effluent keeping an area of the lake free of ice during the winter.
4. The species composition of the diatoms was similar at all stations except in the discharge canal where there was a reduction in the number of diatom species.
5. Navicula cuspidate developed best in the discharge canal in the summer where water temperatures of 31°C were recorded.
6. Amphora ovalis var. pediculus was the dominant diatom species during the winter under ice-cover.
7. The heated effluent had no effect upon the standing crop or species composition of the epipsammon.
8. Results obtained from the sediment core study showed that the shallow littoral zone of the lake is very disturbed due to wind-induced wave action.

     

Benthic algal biomass in an unshaded first-order lowland stream: distribution and regulation

The vertical distribution of algal biomass in the bed sediment and the seasonal development of benthic algae on stones and fine-grained sediments were studied in a small unshaded stream. In addition, field experiments were conducted on the role of irradiance and phosphorus in regulating algal biomass. We found that algal biomass was high at a sediment depth of ten centimetres. Comparison of studies on algal biomass where different depths of the sediment are used should therefore be made with caution. Substrata-dependent differences in algal biomass development were substantial. While algal biomass development on stones was controlled by macroinvertebrate grazing, that on the fine-grained sediment followed the dynamics of incident irradiance, but was attenuated by sediment rebedding. Because of the high grazing pressure on algal biomass on stony substrata, no significant response to phosphorus enrichment was attained. In contrast, algal biomass development on fine-grained sediments was phosphorus-limited. Heavy shading of the fine-grained sediments did not significantly affect algal biomass development, thus suggesting that phosphorus limitation prevents algae from fully utilizing the light resource in this stream. This revised version was published online in July 2006 with corrections to the Cover Date.     

Removal of settled sediments and periphyton from macrophytes by grazing invertebrates in the littoral zone of a large oligotrophic lake

• 1 The resistance and resilience of littoral zone communities to sedimentation will depend both on the extent to which sediment deposition affects productivity, and on interactions within the communities. A series of hypotheses were set up and tested to examine interactions and feedback mechanisms among deposited sediments, periphyton, macrophytes and grazers in a large oligotrophic lake subject to fluctuating sediment loadings.
• 2 Although sediments incorporated into periphyton reduced light availability to macrophytes, periphytic algae were generally the dominant light absorbing component under natural conditions. When grazers were absent, both sediments incorporated in the periphyton and periphytic algal densities increased, and both were then important in reducing light available to macrophytes.
• 3 Grazing rate and assimilation efficiency for the dominant grazer, the prosobranch gastropod Potamopyrgus antipodarum, increased with increasing sediment content under natural lake conditions to reach a maximum at 10 mg sediment cm^?2.
• 4 An increase in sediment incorporation into periphyton films resulted in an increased grazing rate and hence grooming of sediments from macrophytes.
• 5 Grazing invertebrates can play a major role in maintenance of littoral communities by continuously grooming macrophyte hosts of periphytic algae and settled sediments.

     

Distribution and Diversity of Cyanobacteria and Eukaryotic Algae in Qinghai–Tibetan Lakes

Cyanobacteria and eukaryotic algae are important primary producers in a variety of environments, yet their distribution and response to environmental change in saline lakes are poorly understood. In this study, the community structure of cyanobacteria and eukaryotic algae in the water and surface sediments of six lakes and one river on the Qinghai–Tibetan Plateau were investigated with the 23S rRNA gene pyrosequencing approach. Our results showed that salinity was the major factor controlling the algal community composition in these aquatic water bodies and the community structures of water and surface sediment samples grouped according to salinity. In subsaline–mesosaline lakes (salinity: 0.5–50 g L^?1), Cyanobacteria (Cyanobium, Synechococcus) were highly abundant, while in hypersaline lakes (salinity: >50 g L^?1) eukaryotic algae including Chlorophyta (Chlorella, Dunaliella), Bacillariophyta (Fistulifera), Streptophyta (Chara), and Dinophyceae (Kryptoperidinium foliaceum) were the major members of the community. The relative abundance ratio of cyanobacteria to eukaryotic algae was significantly correlated with salinity. The algae detected in Qinghai–Tibetan lakes exhibited a broader salinity range than previously known, which may be a result of a gradual adaptation to the slow evolution of these lakes. In addition, the algal community structure was similar between water and surface sediment of the same lake, suggesting that sediment algal community was derived from water column.