Periphyton Community Structure Research Articles

Responses of phytoplankton and periphyton community structure to an anthropic eutrophication gradient in tropical high-altitude Lake Titicaca

Eutrophication is a global environmental problem in aquatic ecosystems, mainly caused by increased nutrient loads (nitrogen and phosphorus). Phytoplankton and periphyton responses to the nutrients increase and temporal variation may be related to mutual seeding and/or variable environmental constraints. Each of these communities may be useful for characterizing and monitoring eutrophication processes. However, little information exists about the simultaneous responses or interactions between such communities during eutrophication, even less in high-altitude tropical lakes such as Lake Titicaca. Here, we first established a eutrophication gradient with stable isotopes (δ15N and δ13C) and physicochemical variables in a shallow bay of Lake Titicaca. Later, we analyzed the shifts in taxonomic and morphological forms of phytoplankton and periphyton colonizing the underwater stems of totora (Schoenoplectus californicus ssp. tatora), an emergent aquatic macrophyte, along the eutrophication gradient. There is a clear turnover (groups, genera, and morphological forms) in phytoplankton and periphyton and decreased biodiversity along the eutrophication gradient. Gomphonema genus relative abundance increase with eutrophication in both communities, while Achnanthidium abundance decreases. However, other genera behave differently in each community, allowing for the identification of specific bioindicators of eutrophication for phytoplankton (Oscillatoria, Spirogyra, and Euglena) and periphyton (Oedogonium, Stigeoclonium, and Characium). They share genus composition with some taxa showing similar behaviors, thus interactions between phytoplankton and periphyton may exist. We also believe that each compartment can act as a seeding reservoir for the other, though remaining independent to some extent.

Revealing the response characteristics of periphyton biomass and community structure to sulfamethoxazole exposure in aquaculture water: The perspective of microbial network relationships

The widespread application of sulfonamide antibiotics in aquaculture has raised concerns about their adverse environmental impacts. Periphyton plays a crucial role in the aquatic ecosystem. In this study, we examined sulfamethoxazole (SMX) effects on the community structure and interactions of periphyton in simulated aquaculture water. Our findings indicated that the total biomass of periphyton decreased, while the biomass of periphytic algae and the secretion of extracellular polymeric substances (EPS) increased at 0.7 × 10−3 mg/L. Under higher SMX concentrations (5 mg/L and 10 mg/L), periphyton growth was severely inhibited, the microbial community structure of periphyton were sharply altered, characterized by the cyanobacteria growth suppression and decrease in the diversity index of community. Furthermore, elevated SMX concentrations (5 mg/L and 10 mg/L) increased the ratio of negative relationships from 45.4% to 49.4%, which suggested that high SMX concentrations promoted potential competition among microbes and disrupted the microbial food webs in periphyton. The absolute abundance of sul1 and sul2 genes in T2 and T3 groups were 2–3 orders of magnitude higher than those in control group after 30 days of SMX exposure, which elevated the risk of resistance gene enrichment and dissemination in the natural environment. The study contributes to our understanding of the detrimental effects of antibiotic pollution, which can induce changes in the structure and interaction relationship of microbial communities in aquaculture water.

Community structure of periphyton on bamboo substrate in whiteleg shrimp (Litopenaeus vannamei Boone, 1931) pond with semi-biofloc system

Abstract. Arfiati D, Zakiyah U, Anitasari S, Inayah ZN, Pratiwi RK. 2023. Community structure of periphyton on bamboo substrate in whiteleg shrimp (Litopenaeus vannamei Boone, 1931) pond with semi-biofloc system. Biodiversitas 24: 5080-5087. Periphyton is one aquatic organism that attaches to the substrate and can be used as a bioindicator. This study analyzes the community structure and dynamics of periphyton on bamboo substrates in whiteleg shrimp ponds with a semi-biofloc system. The study was conducted from May to July 2022. The bamboo substrate was placed in the ponds, and the samples were taken every seven days to 8 weeks. Identification and calculation of periphyton using Lackey Drop Micro transect Counting Method. The periphyton was found on a bamboo substrate in whiteleg shrimp ponds with a semi-biofloc system consisting of phyto-periphyton and zoo-periphyton. The phyto-periphyton group contains 4 phylum, 21 species, including the Bacillariophyta, Chlorophyta, Cyanophyta, and Ocrophyta. The zoo-periphyton group has 4 phylum, 10 species consisting of Arthropoda, Ciliophora, Nematoda, and Rotifera. The abundance of periphyton found changes every week. The relative abundance of phyto-periphyton includes phylum Bacillariophyta (17-69%), Chlorophyta (1-22%), Cyanophyta (30-65%), and Ocrophyta (0-25%), while zoo-periphyton includes phylum Arthropoda (0-3%), Ciliophora (69-99%), Nematodes (0-2%) and Rotifers (0-28%). The total abundance of phyto-periphyton on bamboo substrate ranged from 223,806-989,398 cells/L, while zoo-periphyton ranged from 396-1,924 individual/L. The diversity, uniformity, and dominance index of phyto-periphyton and zoo-periphyton are moderate. Water quality parameters during the study were relatively good for aquatic organism growth, except for very high total organic matter levels in several weeks.

Community structure of periphyton at floating net cages and non-floating net cages in Laut Tawar Lake, Aceh Tengah

Many activities are carried out around the Laut Tawar lake, one of which is the cultivation of floating net cages that can contribute nutrients to the waters. One of the organisms that can take advantage of the abundance of nutrients in the waters is periphyton. This study aims to examine the community structure of periphyton as natural food in Laut Tawar Lake. This research was conducted in January-April 2022. The results showed that there are 9 classes of periphyton at the KJA station, namely Bacillariophyceae, Chlorophyceae, Cyanophyceae, Rhizopoda, Dinophyceae, Euglenophyceae, Trebouxiophyceae, Klebsormidiophyceae and Coscinodiscophyceae. While, at non-KJA stations there are 7 classes where the Klebsormidiophyceae class and the dinophyceae class are not found at non-KJA stations. The highest abundance at the KJA station was on the 7th day with a value of 108,655 cells/cm2 and non-KJA was 24,552 cells/cm2. The lowest abundance occurred on day 14 at both stations. Periphyton diversity index at KJA and non-KJA stations ranged from 1.88-2.76, which was moderate. The evenness index of periphyton species ranging from 0.61-0.75 was classified as high, while the dominance index ranging from 0.09-0.24 was classified as low. Based on the values obtained, the community structure of periphyton on artificial substrates in the KJA and non-KJA areas in Laut Tawar Lake experienced moderate ecological stress with the community in a stable condition. The t-test results obtained that the abundance values at KJA stations and non-KJA stations had the difference that the abundance of periphyton at KJA stations was greater than at non-KJA stations.

NEW DATA ON THE COMPOSITION OF CYANOBACTERIA AND ALGAE OF SOME WATERCOURSES OF THE KAMCHATKA PENINSULA

The results of studying the biological diversity of the fl ora of freshwater algae in some streams of the Kamchatka Peninsula are presented, the structure of algal periphyton communities is revealed and the ecological characteristics of the studied algofl ora are given. The following rivers were surveyed: Kamchatka, Andrianovka, Plotnikova, Avacha, Paratunka, Gavanka, Kirpichnaya, Karymshina, Mutnushka and the Perviy stream. As a result of sample processing, 193 species, varieties and forms of cyanobacteria and algae from fi ve divisions were found: Cyanobacteria – 5 species, Bacillariophyta – 167 taxa (taking into account varieties and forms – 177), Ochrophyta – 2, Charophyta – 4, Chlorophyta – 5. In the algae communities of the surveyed water bodies, both in terms of abundance in fouling and species diversity, diatoms prevailed. The most common species, often growing on stones and dominating in fouling, were Encyonema minutum, E. silesiacum, Hannaea arcus, Gomphonema ventricosum, Ulnaria inaequalis, Cocconeis placentula, Fragilaria capucina, Nitzschia palea. Melosira varians, Meridion circulare, Planothidium lanceolatum, Gomphonella olivacea, species of the genera Staurosira, Diatoma, Cymbella, Fragilaria and some others were most often present as subdominants. In some cases, Rhoicosphenia abbreviata, Didymosphenia geminata, and Tabularia fasciculata took the fi rst places in terms of abundance. Of the Chlorophyta Ulothrix zonata and Cladophora glomerata were found. In a number of streams Hydrurus foetidus was encountered in mass. The division of Charophyta is represented by fi laments of Spirogyra and single specimens of the genera Closterium and Cosmarium. Cyanobacteria practically did not form mass fouling, except for the Tapinothrix genus. For each surveyed area, the species composition of algae was determined and complexes of dominant species were characterized. Giving a general ecological characteristic of the studied algofl ora, it should be noted that benthic and planktonic- benthic organisms predominate in periphyton communities, which are indiff erent to water salinity and prefer a slightly alkaline habitat.

Distribution and photosynthetic potential of epilithic periphyton along an altitudinal gradient in Jue River (Qinling Mountain, China)

Abstract Periphyton in aquatic ecosystems play a crucial ecological role in element cycling and are susceptible to natural disturbances and anthropogenic activities. To understand the responses of periphytic communities to water quality factors and altitude gradients, DNA metabarcoding was employed to investigate the distribution characteristics of epilithic periphyton (comprising prokaryotes and eukaryotes). Epilithic periphyton and water were sampled at 26 sampling sites with an altitude ranging from 445 to 1,565 m in the Jue River and its three tributaries in Qinling Mountain, China. The altitudinal patterns of water quality variables were initially investigated, followed by redundancy analysis and distance‐based linear models to explore the responses of community structure to altitudes and water quality. Meanwhile, the relationship between these variables and fluorescence parameters to reflect the photosynthesis of epilithic periphyton along an altitudinal gradient was examined. The results indicated that with decreasing elevation, water quality variables including total dissolved solids (TDS), water temperature, conductivity, salinity, and concentrations of ‐N, total nitrogen, and ‐N increased. This pattern was closely associated with the intensification of anthropogenic disturbance downstream. Specifically, higher salinity and water temperature downstream may reduce the prokaryotic biodiversity but promote the diversity and evenness of eukaryotes; higher concentrations of total nitrogen may increase the diversity, richness, and evenness of the whole periphyton community. Furthermore, salinity, nutrients, and TDS were identified as crucial variables shaping periphyton community structure, especially salinity and TDS, which were linked to the growth of chlorophytes. The attenuated maximum photochemical efficiency of periphyton at high altitudes indicated that photosystem II was inhibited, while the enhancement of maximum photochemical efficiency at low altitudes may be attributed to the reduced abundance of synurophyceae and increased chlorophyte abundance with strong photosynthetic capacity. The spatial distribution of the structure and photosynthetic activity of the periphyton community along the altitudinal gradient of the Jue River and its tributaries showed that most water quality variables were negatively correlated with altitude. The photosynthetic efficiency of periphyton declined at high altitudes because the abundance of chlorophytes was lower at higher altitude reaches. This pattern of periphyton structural composition and function with altitude may also exist in other alpine rivers influenced by anthropogenic impacts.

Epiphytic microalgae community as aquatic bioindicator in Brantas River, East Java, Indonesia

Abstract. Arsad S, Putra KT, Latifah N, Kadim MK, Musa M. 2021. Epiphytic microalgae community as aquatic bioindicator in Brantas River, East Java, Indonesia. Biodiversitas 22: 2961-2971. One way to monitor water quality is by using biological indicators, namely epiphytic microalgae (periphyton). This study aims to analyze the epiphytic periphyton community structure and analyze the river health status using a saprobic index. The research location was in the Brantas River, Blitar District, East Java, Indonesia. The method used was a survey with sampling at three sites based on the purposive sampling technique. Periphyton samples were taken using the quadrant transect (5x5 cm²) method and then identified using the Lackey Drop Micro transect Counting Method. The results show that the periphyton community structure is in balance, and there are six divisions of 59 different genera. The six divisions found are Bacillariophyta, Cyanophyta, Chlorophyta, Charophyta, Ochrophyta, and Rhodophyta. The most identified genus is from the Bacillariophyta Division with 28 genera, while the least identified genus is the Rhodophyta division with 1 genus. The abundance ??ranges from 242,800-1,229,174 cells. cm-2, the relative abundance index ??of periphyton ranges from 3-60% (site 1), 9-57% (site 2), 1-62% (site 3), the diversity index ranges from 1.212-2.617 (moderate), the uniformity index ranges from 0.307-2.151 (high), the dominance index ranges from 0.105-0.549 (moderate), and the saprobic index ranges from-0.18 to 0.55. Moreover, supporting water quality parameters are still optimal, except for ammonia and total organic matter parameters that exceed the quality standard. Based on the saprobic value obtained, the water quality of the Brantas River in Tawangrejo Village can be classified into the category of ?/?-mesosaprobic to ?-mesosaprobic saprobic levels with mild to moderate levels of pollution.

Nutrient Exposure Alters Microbial Composition, Structure, and Mercury Methylating Activity in Periphyton in a Contaminated Watershed.

The conversion of mercury (Hg) to monomethylmercury (MMHg) is a critical area of concern in global Hg cycling. Periphyton biofilms may harbor significant amounts of MMHg but little is known about the Hg-methylating potential of the periphyton microbiome. Therefore, we used high-throughput amplicon sequencing of the 16S rRNA gene, ITS2 region, and Hg methylation gene pair (hgcAB) to characterize the archaea/bacteria, fungi, and Hg-methylating microorganisms in periphyton communities grown in a contaminated watershed in East Tennessee (United States). Furthermore, we examined how nutrient amendments (nitrate and/or phosphate) altered periphyton community structure and function. We found that bacterial/archaeal richness in experimental conditions decreased in summer and increased in autumn relative to control treatments, while fungal diversity generally increased in summer and decreased in autumn relative to control treatments. Interestingly, the Hg-methylating communities were dominated by Proteobacteria followed by Candidatus Atribacteria across both seasons. Surprisingly, Hg methylation potential correlated with numerous bacterial families that do not contain hgcAB, suggesting that the overall microbiome structure of periphyton communities influences rates of Hg transformation within these microbial mats. To further explore these complex community interactions, we performed a microbial network analysis and found that the nitrate-amended treatment resulted in the highest number of hub taxa that also corresponded with enhanced Hg methylation potential. This work provides insight into community interactions within the periphyton microbiome that may contribute to Hg cycling and will inform future research that will focus on establishing mixed microbial consortia to uncover mechanisms driving shifts in Hg cycling within periphyton habitats.

The Perifiton Alga Community in Masang Kecil River Receives Liquid Palm Oil Mill Waste in Kinali District, West Pasaman Regency

The study of the periphyton algae community in Masang Kecil River that received palm oil mill effluent in Kinali District, West Pasaman Regency was held from November 2017 to September 2018. This study aims to determine the composition and structure of periphyton communities in the Masang Kecil River in Kinali, West Pasaman. This study used purposive sampling method with a sampling location of 4 stations. Based on this study, 88 species of periphyton were classified as 3 classes i.e Bacillariophyceae (64 species), Chlorophyceae (15 species) and Cyanophyceae (9 species). The average density is 8.967 ind/ cm2. The highest relative density (KR) at stations 1,2 and 3 is Navicula lanceolata and station 4 is Fragilaria capucina. Species that are always found at each station (FK= 100%) are Fragilaria capucina, Navicula lanceolata and Synedra ulna. The diversity index in the Masang Kecil River is classified as medium (H’ = 2.87). Equitability index is evenly distributed (E= 0.64). Dominance index (C= 0.12) there is no dominant species. The similarity index is almost the same except between stations 1 and 3.

Conversion of tropical forests to agriculture alters the accrual, stoichiometry, nutrient limitation, and taxonomic composition of stream periphyton

AbstractThe conversion of forests to agriculture in tropical areas profoundly changes adjacent streams by modifying hydrological conditions, altering light regimes, and increasing nutrient concentrations. In this study, we used an integrative approach to examine how transformations of intact forests affected the physical, chemical, and biological properties of periphyton, in three Brazilian Atlantic rainforest streams. We found that riparian land use change affected the stream periphyton in a variety of ways that were linked to the availability of light and nutrients. Periphyton standing stocks and accrual rates of new periphyton biomass on tiles were higher in deforested reaches than forested reaches. Linear mixed‐model analyses showed that the increase of chlorophyll‐a in the periphyton was explained by the increase in deforestation and soluble reactive phosphorus concentration. Deforestation also altered periphyton stoichiometry as deforested streams exhibited lower C:P, whereas C:N ratios decreased with increasing NH4+ concentration that was higher in some deforested reaches. Periphyton productivity appeared to be limited by light in forested reaches and by nutrients in deforested reaches. There was differential availability of nitrogen and phosphorus in the deforested reaches, depending on land use type, and this resulted in different nutrient limitation. Periphyton community structure shifted from taxa less tolerant to high nutrients and light found in forested sites, to species tolerant to these conditions dominating periphyton assemblages in deforested sites. The loss of canopy cover was the strongest predictor of community composition for all sites, whereas phosphorus concentration was the best predictor of algal abundance in deforested reaches. This study highlights the complex effects of forest clearing on stream periphyton, ranging from changes to biomass accrual, nutrient limitation, stoichiometry, and community structure. We show the importance of using a comprehensive approach to help determine and predict how deforestation impacts stream ecosystems.

Periphyton Community Structure of the Spring-fed Foot-hill Stream Tamsa Nadi from Doon Valley, Uttarakhand, India

Periphyton Community Structure of the Spring-fed Foot-hill Stream Tamsa Nadi from Doon Valley, Uttarakhand, India

Struktur Komunitas Alga Perifiton Sungai dalam Gua Batu Asahan di Sumpur Kudus Kabupaten Sijunjung Sumatera Barat

The cave ecosystem has a unique environment because it receives minimal sunlight and does not even get sunlight at all. Dark conditions in the cave will affect producers such as periphyton algae that live in rivers in caves that need sunlight for photosynthesis. This study aims to determine the periphyton community structure in the river in the Batu Asahan Cave in Sumpur Kudus, Sijunjung District, West Sumatra. This research held in August 2016. The research was carried out by survey method at 3 stations: bright, dim and dark zones. The results showed that periphyton were found as many as 22 species classified as Bacillariophycea 13 species, Cyanophyceae 5 species, Chlorophyceae and Euglenophyceae each of 2 species. Based on the number of individuals Bascillariophyceae 67.0%, Cyanophyceae 24.49%, Chlorophyceae 4.79% and Euglenophyceae 3.72%. Population density in each zone was low, ranges from 1.26 - 2.82 ind / cm2. The dominant species vary in each zone which is the highest shown by Synedra ulna (Bacillariophyceae) and Oscillatoria tenuis (Cyanophyceae). Diversity index ranging from 2.11-2.47 is not significantly different between zones, indicating the quality of clean water. The equitability index was high (E = 0.88-0.96) show the populations in the community evenly. Similarity index between zones was low (C = 25 - 56%). Fisicochemical factors of water indicate the quality of clean water supports the life of periphyton algae in the river.

Seasonal shifts in the importance of bottom–up and top–down factors on stream periphyton community structure

We examined the importance of temporal variability in top–down and bottom–up effects on the accumulation of stream periphyton, which are complex associations of autotrophic and heterotrophic microorganisms. Periphyton contributes to primary production and nutrient cycling and serves as a food resource for herbivores (grazers). Periphyton growth is often limited by the availability of nitrogen and phosphorus, and biomass can be controlled by grazers. In this study we experimentally manipulated nutrients and grazers simultaneously to determine the relative contribution of bottom–up and top–down controls on periphyton over time. We used nutrient diffusing substrates to regulate nutrient concentrations and an underwater electric field to exclude grazing insects in three sequential 16–17 day experiments from August to October in montane Colorado, USA. We measured algal biomass, periphyton organic mass, and algal community composition in each experiment and determined densities of streambed insect species, including grazers. Phosphorus was the primary limiting nutrient for algal biomass, but it did not influence periphyton organic mass across all experiments. Effects of nutrient additions on algal biomass and community composition decreased between August and October. Grazed substrates supported reduced periphyton biomass only in the first experiment, corresponding to high benthic abundances of a dominant mayfly grazer (Rhithrogena spp.). Grazed substrates in the first experiment also showed altered algal community composition with reduced diatom relative abundances, presumably in response to selective grazing. We showed that top–down grazing effects were strongest in late summer when grazers were abundant. The effects of phosphorus additions on algal biomass likely decreased over time because temperature became more limiting to growth than nutrients, and because reduced current velocity decreased nutrient uptake rates. These results suggest that investigators should proceed with caution when extending findings based on short‐term experiments. Furthermore, these results support the need for additional seasonal‐scale field research in stream ecology.

Combined CdS nanoparticles-assisted photocatalysis and periphytic biological processes for nitrate removal

The concept of improving in-situ nitrate removal was demonstrated in a CdS nanoparticles (NPs)-assisted periphyton bioelectrochemical system (PCdS-BES). Compared to the control (periphyton bioelectrochemical system, P-BES), nitrate reduction to nitrogen gas by the PCdS-BES was enhanced by 1.5 times on day 7 under stimulated sunlight irradiation (20 W m−2), avoiding nitrous oxide emission. The presence of CdS NPs optimized the community structure of periphyton, enhanced its activities (represented by ATPase), stimulated more extracellular polymeric substance (EPS) production and increased the relative abundance of electroactive bacteria strains (e.g. Family Xanthomonadaceae, Hyphomonadaceae and Sphingobacteriales). The enhancement of nitrate reduction under irradiation was primarily attributed to the synergistic effect of EPS, electroactive bacteria strains and CdS NPs. Specifically, CdS NPs provided photoexcited electrons under light irradiation. The EPS facilitated the stability of CdS NPs in the periphyton matrix and separation of photo-induced electron-hole on the surface of CdS NPs. EPS served as extracellular electron transfer mediators for electron transfer from CdS NPs to microorganisms. The electroactive bacteria were beneficial to the acquisition of electrons produced by CdS NPs under irradiation, promoting catalytic nitrate reduction. This study gives an insight into the mechanism of nitrate reduction via the synergistic action of photoexcited electrons, EPS and electroactive bacteria. The successful combination of photocatalyst (i.e. CdS NP) and microbial community in BES also provides a promising approach for nitrate removal.

Long-term exposure to silver nanoparticles affects periphyton community structure and function

Silver nanoparticles (AgNPs) are widely used as antimicrobial agents.

Impact of Talc Ore Mining on Periphyton Community Structure and Water Environment

In order to explore the impact of Talc ore mining on aquatic ecosystems, periphyton communities and environmental factors from control portion, impacted portion and recovery portion separately were investigated and analyzed. Samples were collected from upstream Tanghe River (an important tributary of Tazi River) in November 2015, April 2016, and July 2016. Mann-Whitney U test was applied to compare the differences in environmental factors and periphyton community structures among three portions. Spearman correlation analysis, canonical correspondence analysis, and t-value biplot analysis were used to determine the relationship between the environmental factors and periphyton community structures. In the control and recovery portions, mass concentrations of magnesium (Mg), selenium (Se), arsenic (As), iron (Fe), molybdenum (Mo), bicarbonate ion (HCO3-), nitrate ion (NO3-), power of hydrogen (pH) and electric conductivity (EC), were the highest, and in the impacted portion, mass concentrations of potassium(K), sodium (Na), strontium (Sr), barium (Ba), silicon dioxide (SiO2), and dissolved oxygen (DO) were the lowest. The mass concentrations of Mg, Mo, As, EC, and HCO3- were significantly different (P<0.05) among the three portions. In control and recovery portions, the periphyton density, species richness, diatom siltation index, and relative abundance of Achnanthes sp. were the highest, while in the impacted portion, the percentage of handle diatom, the relative abundance of Surirella sp., and relative abundance of Navicula sp. were the lowest. Species richness of periphyton was significantly different (P<0.05) among the three portions. In summary, Mg, EC, and HCO3- from Talc Ore mining had significant impacts on periphyton assemblage structure.

Struktur Komunitas Perifiton Pada Lamun Jenis Thalassia hemprichii dan Cymodocea rotundatta di Kawasan Pantai Sanur

Seagrass has function as nursery ground, spawning ground, feeding ground and habitat for many coastal organism (benthic, fish and epiphytes). Tourism activities in Sanur beach, the habitat of seagrass, could change the water condition, it indirectly influencing the existences of seagrass plants and periphyton in Sanur beach. The aim of this study are to analyze community structure of periphyton on seagrass leaves (Thalassia hemprichii and Cymodocea rotundatta) and its relationship with water parameters in four stations at Sanur beach area that has the unique characteristics. Water parameters measured were temperature, salinity, DO (Dissolved oxyen), pH, nitrate, phosphate, and TSS (Total Suspended Solid). Data analysis using PCA (Principal Component Analysis) to see the parameters that most influence on the abundance of periphyton. The results showed diversity index (H’) of periphyton is moderate, eveness index (E) moderate to high, and dominance index (C) is low to medium. It concluded that conditions of Sanur waters is stable but it is easily changed due to anthropogenic influences. PCA analysis showed that the parameters of the water have different effects on the abundance of periphyton at each seagrass leaves. Periphyton on Thalassia hemprichii was influenced by TSS, while Cymodocea rotundatta was influenced by phosphate, nitrate, temperature, DO, and TSS.

Struktur Komunitas Perifiton Dibagian Hulu Sungai Cisadane, Kawasan Taman Nasional Gunung Halimun Salak, Jawa Barat

ABSTRACT Perifiton is one community of organisms that can adapt and thrive in the river, and relatively settled in one location. Riparian vegetation in the Mountain Halimun-Salak National Park could be expected to affect the community structure of periphyton. The purpose of this study was to identify the community structure of periphyton on different vegetation canopy coverage, to analyze relationship between the communities structure of periphyton and upstream Cisadane water quality conditions, and to determine water quality based on perifiton community. There were three sets three stations based on canopy coverage (80%, 60%, dan 40%). The results showed two groups of stations, the high canopy coverage (80%) and the low canopy coverage. The highest perifiton abundance was found at stations low canopy coverage, that dominated by Bacillarophycae, Pennales order, especially Navicula with higher rate of succesion than the higher canopy caverage. Abundance of periphyton of low canopy coverage was affected by ammonium, turbidity, and water current. Furthermore, in stations high canopy coverage it was influenced by orthophosphate and currents. As a whole, the periphyton community at upstream of Cisadane indicated a good condition of water quality. Keywords: canopy, periphyton, succession rate

Responses of periphyton morphology, structure, and function to extreme nutrient loading

Periphyton have been widely applied in aquaculture systems, however, little information is available on how periphyton respond to such high nutrient levels in water. Thus, changes in the morphological characteristics, community structure, and metabolic function of periphyton under high eutrophic waters were evaluated. The results indicated that the morphology of periphyton was affected by increasing the nutrient concentration of water, which shifted the micromorphology of periphyton from spheriform to filamentous. The periphyton under higher water nutrient levels were able to utilize more carbon source types. Additionally, higher water nutrient levels increased the bacterial and protozoal proportions in periphyton. This study fills the gap in knowledge about the responses of periphytic communities to extremely eutrophic waters. It provides valuable information on the full understanding of the periphyton-nutrient relationship in aquaculture systems, which is beneficial for regulating the microbial species or communities in periphyton by manipulating the nutrient levels in water.

Independent effects of grazing and tide pool habitats on the early colonisation of an intertidal community on western Antarctic Peninsula

Prevailing environmental conditions can modulate the structuring role of biotic interactions. In intertidal habitats, less stressful environmental conditions and/or higher grazer densities may allow grazing effects to be stronger in tide pools than on emergent rocks. To test this hypothesis, we conducted a manipulative experiment on an intertidal rocky shore in Fildes Bay, King George Island, in which the effect of the dominant grazer Nacella polaris on the structure of benthic periphyton communities was compared between emergent rock and tide pool habitats. Also, we determined the spatial variation in density, weight, and maximum length of individuals of N. polaris in both habitats. The density of N. polaris was significantly larger in tide pools than on emergent rocks. Contrarily, we observed no significant differences in morphological parameters of N. polaris between both habitats or between intertidal elevations. In the manipulative study, we observed a greater taxonomic richness, diversity, and abundance of periphyton on emergent rocks than in tide pools. These variables also showed, in comparison with control areas, significantly higher values in experimental areas where herbivores were excluded by means of stainless-steel fences. The effects of habitat and grazer exclusion treatments were independent of each other, as no statistically significant interaction between both factors was observed. Our results showed significant, but independent, effects of tide pool habitats and grazing on the early colonisation of these assemblages. Albeit the grazing effects of other herbivores such as amphipods and small gastropods cannot be ruled out, we suggest that traits of N. polaris, such as high mobility and circadian activity, allow this species to exert a firm control on the intertidal Antarctic assemblages across local environmental conditions.