A comparison of algal periphyton composition on eleven species of submerged macrophytes

Summary The composition of algal periphyton was examined on eleven species of submerged macrophytes collected at a depth of 0.25 m in Sewell Lake, southwestern Manitoba, a shallow nitrogen and phosphorus rich lake. There were substantial differences in the periphyton on all macrophyte species. Diatom subcommunities were the most similar, while the green algal subcommunities were the most dissimilar on different plant hosts.Potamogeton zosteriformis differed the most from all other macrophytes with respect to the composition of its periphyton. These results and a comparison of the literature suggest that the composition and structure of periphyton communities on living substrates is a product of the interaction of many variables, determined by the characteristics of the host plant, the external environment and the algae themselves. Studies of periphyton at a given site must take into account the various substrates available.     

Influence of substrate type on periphyton biomass and nutrient state at contrasting high nutrient levels in a subtropical shallow lake

How substrate affects periphyton biomass and nutrient state at different, but high, nutrient levels was tested in three large enclosures in a hypereutrophic subtropical shallow lake. We compared periphytic characteristics (1) on three hard substrates (stone, bamboo, and wood) incubated for 2 weeks and 1 year, respectively, to investigate the existence of the influences of substrate type at hypereutrophic levels, and (2) on artificial plants with contrasting (parvopotamid-like and myriophyllid-like) soft substrate morphology. In general, periphytic biomass and nutrient state were sensitive to variations in nutrient level, incubation time, hard substrate type (except 2-week incubated) and substrate morphology, but to a varying extent. The periphyton nutrient content increased with increasing nutrient levels on most substrates. Long-time incubated substrates supported more periphytic biomass, had a higher nutrient content and autotrophic proportion, while the effect of nutrient level on nutrient content in the periphyton was independent of incubation time. The effects of hard substrate type on periphyton characteristics were much weaker than those of nutrient level. By contrast, the effects of soft substrate morphology on periphyton biomass and carbon: nutrient ratios surpassed those of nutrient level. Chlorophyll a, dry mass, and ash free dry mass were much higher on parvopotamid than on myriophyllid substrates. Our results show that periphyton biomass and nutrient state are influenced by both substrate and nutrient level even in hypereutrophic lakes, which might have cascading effects on the benthic food web.     

空间层次及人工基质对着生藻类建群特性的影响

为全面了解着生藻类在建群中群落变化的生态学特性,揭示着生藻类的建群规律,在以丝状藻类为优势藻的生态塘中,采用花岗岩和瓷砖为附着材料,设置水体底部和中部为附着位点,进行频次为10d的采样分析。结果表明,生态塘中共检出8门73属117种着生藻类,其中以硅藻、蓝藻、绿藻为优势类群。同时不同人工基质和不同空间层次条件下着生藻类的建群特征较一致,早期以单细胞硅藻如舟形藻(Navicula sp.)、脆杆藻(Fragilaria sp.)、曲壳藻(Achnanthes sp.)等为优势,后期以丝状藻类如鞘丝藻(Lyngbya sp.)、颤藻(Oscillatoria sp.)、伪鱼腥藻(Pseudanabaena sp.)等为优势;研究结果发现不同人工基质(花岗岩和瓷砖)对着生藻类的种类组成、细胞密度、生物量和藻类多样性无显著影响,花岗岩和瓷砖上附着的着生藻类具有较高的相似性;但不同的空间层次对着生藻类建群特征影响明显,水体底部具有更多的硅藻种类数,中部具有更多的绿藻,随着建群时间的发展,蓝藻比例不断增加;就生物量而言,底部的着生藻类叶绿素a显著高于水体中部,但两者的细胞密度无显著性差异;随着建群过程的发展,水体底部的着生藻类生物量达峰值所需的时间比中部更长。通过相关性分析,生态塘中着生藻类的生长主要受总磷的影响。     

Periphyton growth and diatom community structure in a cooling water pond

Periphyton (Aufwuchs) accumulation was measured on artificial substrates in a pond in central Finland which receives warm cooling-water effluent from a power plant. The growth of periphyton was generally more rapid on the substrates during the first two weeks of colonization near the inflow of the warm water effluent than in the middle of the pond. The maximum accumulation of periphyton was in spring and autumn (dry weight maximum at warm effluent was in spring 3.5 mg DW cm⁻²,2.65 mg AFDW cm⁻²; chlorophyll a maximum 3.96 μg cm⁻² was found in autumn at pond-middle station). During mid-winter months the growth was strongly limited by solar radiation, but the growth was also slow at both stations in the summer months, when the power plant was out of operation. The periphyton accumulation rate was fastest near the water surface and decreased rapidly with increasing depth. A total of 167 diatom species were found in periphyton samples. However, most species were rare; many of the dominants were common to both plankton and periphyton. Species similarity analyses (Jaccard's similarity) between 10 different diatom communities (including periphyton from 9 different types of substrates and phytoplankton) indicated low similarity index values although differences between communities were not significant.     

Phosphorus Availability Alters the Effects of Silver Nanoparticles on Periphyton Growth and Stoichiometry

Exposure to silver nanoparticles (AgNPs) may alter the structure and function of freshwater ecosystems. However, there remains a paucity of studies investigating the effects of AgNP exposure on freshwater communities in the natural environment where interactions with the ambient environment may modify AgNP toxicity. We used nutrient diffusing substrates to determine the interactive effects of AgNP exposure and phosphorus (P) enrichment on natural assemblages of periphyton in three Canadian Shield lakes. The lakes were all phosphorus poor and spanned a gradient of dissolved organic carbon availability. Ag slowly accumulated in the exposed periphyton, which decreased periphyton carbon and chlorophyll a content and increased periphyton C:P and N:P in the carbon rich lakes. We found significant interactions between AgNP and P treatments on periphyton carbon, autotroph standing crop and periphyton stoichiometry in the carbon poor lake such that P enhanced the negative effects of AgNPs on chlorophyll a and lessened the impact of AgNP exposure on periphyton stoichiometry. Our results contrast with those of other studies demonstrating that P addition decreases metal toxicity for phytoplankton, suggesting that benthic and pelagic primary producers may react differently to AgNP exposure and highlighting the importance of in situ assays when assessing potential effects of AgNPs in fresh waters.     

Interactions between neighboring algae and snail grazing in structuring microdistribution patterns of periphyton

The micro-distribution of periphyton (filamentous algae) on homogeneous substrates was examined in experimental tanks with and without the pressure of grazing snails. The growth of periphyton attached to artificial substrate was estimated at a small spatial scale (9.3 mm×9.3 mm cells) by varying the number of grazers (0, 5, or 10 snails per tank), using image processing analysis without removing the periphyton. The results suggest that periphyton growth within a cell was negatively affected by the biomass of periphyton in the cell but was positively affected by the biomass of periphyton in neighboring cells. A semivariogram analysis indicated that spatial heterogeneity increased with increasing grazing pressure. The size of patches was not clearly related to the number of snails, but there was a tendency for relative patch size to increase with snail density. Computer simulations were also conducted to examine factors affecting the degree of spatial heterogeneity. The simulation studies indicated that snails should graze a site that was previously grazed in order to produce the observed spatial heterogeneity of periphyton. The results also indicated that the positive effects of neighboring periphyton on the growth of algae might create patches. The interactions among neighboring algae and snail grazing might be an important factor creating the spatial heterogeneity of periphyton even on homogeneous substrates.     

Phosphorus removal from eutrophic lakes using periphyton on submerged artificial substrata

The potential of periphyton for phosphorus removal from lakes has been investigated using a novel method involving polypropylene (PP) substrate carriers submerged in the pelagial. The study area Lake 'Fühlinger See' in Cologne (Germany) is a complex of mesoeutrophic gravel pit lakes. The whole site is intensively used as a recreation area. Visitors are thought to be the most important single contributors to lake eutrophication. Carriers were exposed at different depths (2, 3.5, 5 m), for different time intervals (1–8 months) and from March to November PP-sheets were readily colonised by periphyton and a biofilm consisting mainly of benthic diatoms developed. Seasonal variability of periphyton on substrates was observed since filamentous green algae colonised the artificial substrates mainly between July and November. Chlorophyll a content of periphyton on the PP-fleece was up to 240-fold higher than chlorophyll a concentrations in the same volume in the epilimnion. Up to around 100 mg of total phosphorus per m² PP-fleece was bound and can be eliminated from the lake by removal of the substrate carriers together with the periphyton after four months of exposure. Though large-scale validations are needed, this method may be applicable as a technique to harvest phosphorus from the water column in larger-scale settings.     

Initial colonization of periphyton on natural and artificial apices of Myriophyllum heterophyllum Michx

SUMMARY. 1. The initial colonization of periphyton on natural and artificial apices of Myriophyllum heterophyllum Michx was compared at three depths in the littoral zone of Lake Winnipesaukee, a soft-water New England lake. After a 1 week incubation period, the apices were sampled and the periphyton was removed and counted as numbers of periphyton organisms per centimetre of stem.
2. Initial colonization on both substrates was characterized by diatoms, particularly small single-celled species, throughout the spring and summer. Blue-green and green algae occurred in low numbers on both substrates during mid-summer, usually forming a greater percentage of the population of the natural apices. Blooms of the green alga Zygnema sp. dominated both substrates in late August.
3. Community composition generally did not differ significantly by depth or substrate on the natural and artificial apices: however, total abundance was significantly greater on the natural apices. M. heterophyllum appeared to serve as a neutral substrate in terms of community composition but had a positive effect on the total numbers of algae.     

A quantitative method for determining the efficacy of algicides in industrial cooling towers

Summary Quantitative sampling of periphyton from natural substrates is difficult and uncommon due to the nonhomogenous and irregular nature of most natural substrates. This paper describes an experimentally verified method for quantitative sampling of periphyton directly from the relatively homogenous and regular upper deck of a cooling tower.     

Effects of copper on periphyton communities assessed in situ using chemical-diffusing substrates

Chemical-diffusing substrates were designed to allow delivery of toxicants to mature periphyton communities under natural conditions without contaminating the surrounding environment. Artificial stream validation studies were conducted in which the effects of substrate-released copper (Cu) on periphyton communities were compared to those generated in a more conventional manner (via water column additions). Effects of copper on the following community parameters were assessed: total community biomass (measured as ash-free dry mass), relative chlorophyll a (chl a and adenosine triphosphate contents, and relative biomass of heterotrophic bacteria. Exposure of more laboratory periphyton communities to substrate-released Cu generated dose-response relationships and recovery models that were indistinguishable from those generated by the conventional route of exposure. The results of this study demonstrate the utility of chemical-diffusing substrates in field validations of laboratory toxicity tests and in investigations of the effects of stress history on periphyton tolerance to toxicants. This revised version was published online in September 2006 with corrections to the Cover Date.     

Hydraulic influences on periphyton and benthic macroinvertebrates: simulating the effects of upstream bed roughness

1. Hydraulic conditions, periphyton biomass and invertebrate communities were compared on artificial substrates exposed to a range of upstream roughness conditions across an area of uniform current velocity and depth in a gravel-bedded river. The effect of river bed roughness was simulated by installing roughness elements upstream of artificial substrates.
2. Increasing upstream roughness reduced the average near-bed velocity above the substrates and increased short-term variability in velocity (i.e. turbulence).
3. Periphyton chlorophyll a density showed a general decline with near-bed velocity and was significantly lower on the substrates exposed to the river bed reference and 0 mm roughness treatments than the 110 mm roughness elements. Chlorophyll a was also negatively correlated with the abundance of larger collector-browsing invertebrates. This indicates that effects of the changes in hydraulic conditions on invertebrates may have contributed to the observed treatment effects on periphyton.
4. Invertebrate abundance and diversity declined with increasing upstream roughness. Filter-feeders, collector-browsers and predatory invertebrates all declined in abundance with increasing upstream roughness, but the effect was strongest for filter-feeders. Eight of the nine most common taxa showed significant treatment effects. The orthoclad chironomid, Eukiefferiella sp., was not influenced strongly by upstream roughness, but its abundance was correlated significantly with periphyton biomass.     

A portable pump sampler for lotic periphyton

A sampling technique for collecting lotic periphyton on sedimentary substrates using a peristaltic pump is described. Quantitative samples of periphyton standing crop and colonization rate are collected by the same procedure. The technique eliminates human disturbance problems associated with floating artificial samplers by establishing permanent sampling sites directly on submerged substances.     

The Effects of Periphyton, Fish and Fertilizer Dose on Biological Processes Affecting Water Quality in Earthen Fish Ponds

The potential of periphyton-based aquaculture in South Asia is under investigation in an extensive research program. This paper is a further analysis of data from four experiments carried out in that framework, to explore periphyton, fish and fertilizer dose effects on water quality. Factor analysis and ANOVA models applied to a data matrix of water quality parameters in ponds with and without artificial substrates (bamboo poles and kanchi sticks), with and without fish (filter feeders catla and rohu, with and without bottom feeder kalbaush), and with a standard or 50% increased fertilizer dose, allowed us to identify the underlying ecological processes governing this novel periphyton-based pond system, and construct conceptual graphic models of the periphyton–environment relationships observed. We clearly established that the phosphorus flow is mainly linked to phytoplankton activity in the water column and decomposition on the pond bottom, while nitrogen flow is mainly linked to autotrophic (photosynthesis) and heterotrophic (decomposition and nitrification) processes that take place in the periphyton in addition to the water column and pond bottom. Consequently, disruption of the pond bottom by bottom feeding fish primarily promoted phosphate cycling and phytoplankton, while periphyton development on the supplied substrates and fertilization mainly improved oxygen balance and nitrogen related processes developing in the water column. The use of bamboo poles led to better results than kanchi sticks, related to the greater autotrophic periphyton development on bamboo and to the larger surface of bamboo poles that facilitate fish grazing and periphyton dislodgment that in turn have a renewal effect on periphyton. Stocking bottom feeding fish produces a fertilizing effect through the food web that benefits the filter-feeding fish and that makes it unnecessary to increase the dose of inorganic and organic fertilizers applied to the ponds. Thus, the output of this analysis will help the fish farmers in resource constrained countries to improve their production in periphyton-based ponds just by choosing bamboo substrates, stocking a bottom feeder fish together with the filter feeders, and saving money on fertilizers.     

Photosynthetic pigments of phytoperiphyton in the Sylva River (Middle Ural)

The pigment composition of phytoperiphyton algocenoses on stones and macrophytes (Potamogeton lucens L., P. perfoliatus L., P. gramineus L., P. pectinatus L., Mirophyllum spicatum, Petasites hybridus (L.) Gaertn., Mey. et Sxherb, Nuphar lutea L., and Alisma plantago-aquatica L.) in the submontane Sylva River (Middle Ural) is considered based on the surveys of 2000–2012. The wide variability in the content of plant pigments in phytoperiphyton depends on the season and type of substrate. The maximum values similar for all substrates are observed at the end of summer. The concentrations of Chl a increase during warm low-water years. Chlorophyll a prevails among green pigments in periphyton; the relative concentration of other pigments is lower. The concentration of plant carotenoids in epiphyton is slightly higher compared to epilithon and is comparable to the Chl a level. The trophic state index of the Sylva River may be determined as mesotrophic or weakly eutrophic when the Chl a concentration in phytoperiphyton is used as a marker.     

Hydraulic influences on periphyton and benthic macroinvertebrates: simulating the effects of upstream bed roughness

1. Hydraulic conditions, periphyton biomass and invertebrate communities were compared on artificial substrates exposed to a range of upstream roughness conditions across an area of uniform current velocity and depth in a gravel-bedded river. The effect of river bed roughness was simulated by installing roughness elements upstream of artificial substrates.
2. Increasing upstream roughness reduced the average near-bed velocity above the substrates and increased short-term variability in velocity (i.e. turbulence).
3. Periphyton chlorophyll a density showed a general decline with near-bed velocity and was significantly lower on the substrates exposed to the river bed reference and 0 mm roughness treatments than the 110 mm roughness elements. Chlorophyll a was also negatively correlated with the abundance of larger collector-browsing invertebrates. This indicates that effects of the changes in hydraulic conditions on invertebrates may have contributed to the observed treatment effects on periphyton.
4. Invertebrate abundance and diversity declined with increasing upstream roughness. Filter-feeders, collector-browsers and predatory invertebrates all declined in abundance with increasing upstream roughness, but the effect was strongest for filter-feeders. Eight of the nine most common taxa showed significant treatment effects. The orthoclad chironomid, Eukiefferiella sp., was not influenced strongly by upstream roughness, but its abundance was correlated significantly with periphyton biomass.     

Effects of nutrients and light on periphytic biomass and nutrient stoichiometry in a tropical black-water aquatic ecosystem

This article aims to test the light-nutrient hypothesis (LNH) in a periphytic community in a tropical black-water lake. Individual and interactive effects of light and nutrient availability were assessed with periphyton biomass accrual, nutrient content, and nutrient stoichiometry. We performed a manipulative field experiment with a 4 × 2 factorial design. We used nutrient diffusing substrates to produce four different nutrients treatments: Control (no nutrient added), nitrogen amended (N), phosphorus amended (P) and combined N and P amendment (NP). Two light levels were also considered: high light (near surface water) and low light (near bottom water). Light and nutrients individually and interactively caused significant changes in aggregate periphyton community properties. Total and autotrophic biomasses were significantly higher in high light conditions and in nutrient enriched treatments. Autotrophic biomass was significantly higher in N enriched treatment whereas total biomass was mainly affected by the joint addition of N and P. At lower light availability periphyton growth was limited, even in enriched treatments. Light also strongly affected periphyton nutrient content. Periphyton C, N and P in general increased when subjected to high light conditions. As predicted by the LNH, light promoted an increase in periphyton C:P ratios in P deprived treatments, but an opposite effect was observed on C:N ratios, especially in N-enriched treatments. This experiment revealed that light availability strongly limits the propagation of nutrient effects on periphyton growth. Such complex interdependencies on basal resources affect the proportion of autotrophic to total periphytic biomass that can be an important mechanism to explain variation in the nutrient stoichiometry of periphyton in nature.     

Influence of the colonizing substrate on diatom assemblages and implications for bioassessment: a mesocosm experiment

Although diatoms are important bioindicators of ecological quality, their ecological traits are still not well understood. A major issue is that of substrate preferences, which may result in differences in production, and assemblage structure and composition, and which should therefore be taken into account for ecological quality assessment studies. Thus, in this work, the periphyton grown on sand and ceramic tiles in indoor controlled channels were compared to understand whether substrate differences lead to differences in: periphyton production (chlorophyll-a), chlorophyll-b and c concentrations, diatom assemblages (diversity-Shannon-Wiener, cell density, taxonomic composition, trait proportions), and ecological quality assessments (IPS-‘Indice de Polluosensibilité Spécifique’). A combined inoculum of periphyton from four Portuguese streams was introduced to the running channels (six sand and six tile) and left to colonize for 35 days. Epilithic (tiles) and epipsammic (sand) assemblages were sampled at days 14 and 35. We verified that there were no differences in chlorophyll-a concentration over time and between substrates. On both sampling occasions, the epipsammic assemblages had higher concentration of chlorophyll-c and diatom density but without significant differences over time in each substrate. The taxonomic composition was different between substrates and over time. However, these differences were not reflected in ecological quality assessment. The diversity was also similar between substrates in both sampling occasions, but it was higher at day 14. Mobile and stalked species were more abundant over the entire study and differed significantly between substrates, with the epipsammic assemblages presenting higher abundances of both traits. We concluded that the colonizing substrate influences diatom assemblages but not the ecological quality assessment.     

Responses of stream algae to grazing minnows and nutrients: a field test for interactions

Summary Previous studies have shown that an algivorous grazing minnow (Campostoma anomalum) is the major herbivore in Brier Creek, a hardwater stream in south central Oklahoma. In summer and autumn schools of Campostoma virtually eliminate algae from substrate surfaces in deeper areas of some pools. The pool-to-pool distributions of algae and Campostoma reported for this stream could occur if nutrient limitation permits grazing by Campostoma to outrun algal growth. To test this hypothesis, mesh pens were built to exclude Campostoma from substrates in each of four typical Campostoma pools. N+P+K lawn fertilizer was added daily to two of the four pools; the other two, which received no fertilizer additions and which were not visibly affected by fertilizer transported downstream from the pools enriched with nutrients, served as controls. Algae accumulated rapidly on natural substrates and on unglazed ceramic tiles in grazer-exclusion pens in pools receiving N+P+K additions and more slowly in pens in both control pools. Periphyton biomass on grazed substrates in all four pools remained low throughout the experiment. Hence, Campostoma at normal densities were able to outrun algal growth even when nutrients were added. Eleven days after the experiment started, I determined biomass, biomass-specific net primary productivity, and areal net primary productivity of periphyton on substrates exposed to all combinations of grazer (+,0) and nutrient (+,0) treatments. Grazing increased biomass-specific primary productivity, prevented accumulation of biomass, and decreased areal primary productivity of periphyton. Additions of N+P+K increased biomass-specific net primary productivity of grazed and ungrazed periphyton and markedly increased biomass of periphyton on substrates protected from Campostoma. Although food supply for Campostoma appeared to be greater with nutrient additions, condition of Campostoma in pools receiving N+P+K was not significantly different from Campostoma collected from control pools 35 days after the experiment started. I conclude that although nutrient supply limits biomass-specific primary productivity of periphyton in Brier Creek, nutrient limitation in this stream exacerbates, rather than causes, the visually conspicuous pool-to-pool complimentary distribution of algae and Campostoma: in this stream, grazing by Campostoma at natural densities can outrun periphyton growth even when nutrients are added.     

Effects of desiccation duration on the community structure and nutrient retention of short and long-hydroperiod Everglades periphyton mats

Responses of periphyton communities to different relevant durations of dry down were assessed. Long-hydroperiod sites within Everglades National Park remain wet for greater than 8 months of the year while short-hydroperiod mats are wet for fewer than 4 months of the year. Dry down duration of long and short-hydroperiod Everglades periphyton was manipulated from 0 to 1, 3, or 8 months after which periphyton was rewetted 1 month and examined for algal species composition. The effects of desiccation and rewetting on periphyton nutrient retention were also assessed. Relative abundance of diatoms declined from an average of 47% in the long-hydroperiod community at the start of the experiment to 24% after 1 month of desiccation and only 12% after 8 months of desiccation. Short-hydroperiod periphyton contained a lower proportion of diatoms at the outset (3%), which declined to less than 1% after the 8-month desiccation treatment. A significant increase in the filamentous cyanobacteria Schizothrix calcicola occurred in long-hydroperiod periphyton mats during this same period, but not in short-hydroperiod mats. Long-hydroperiod periphyton communities had a greater response to desiccation overall, but short-hydroperiod community structure responded to desiccation more rapidly. Because short-hydroperiod communities dry frequently, they appear to cope better to desiccating conditions than long-hydroperiod periphyton communities. This is indicated by the dominance of desiccation resistant algal taxa such as the cyanobacterial filaments S. calcicola and Scytonema hofmanni. Long-hydroperiod periphyton mat communities converge compositionally to short-hydroperiod periphyton communities after prolonged desiccation. Desiccation and rewetting caused long-hydroperiod periphyton to flux greater concentrations of nutrients than short-hydroperiod periphyton. Significant increases in efflux occurred from 1 to 8 months for total phosphorus (TP) and from 1 to 3 and 8 months for total nitrogen (TN) and total organic carbon (TOC). Thus, changes in periphyton mat community structure and function with altered hydroperiod may have long-term ecosystem effects.