Algal Species Richness Research Articles

Epiphytic Algae on Dominant Macrophytes in Lotic Ecosystems in the Eastern Flanks of Mount Cameroon

Aims: This study was designed to assess quantitative estimates of epiphyte biomass and diversity on the dominant macrophytes in two rivers in the Eastern flanks of Mount Cameroon. Place and Duration of Study: Two sets of water samples were collected at the top 10cm of the rivers for nutrient and chlorophyll a determination. A single preliminary collection of algal epiphytes from partially submerged aquatic macrophytes was carried out from the littoral zone of Ndongo and Limbe rivers, between May and June 2023. Methodology: The sedimentation technique was employed in the study. Three slides were prepared for each aquatic macrophyte sample for microscopic analysis. Identification was done by comparative morphology using relevant journals and textbooks. Results: All variables related to water clarity (TSS, Phytoplankton Chl a, HC) assessed during the study were similar in both rivers. Water clarity based on HC values was below 6 mg/l implying both rivers were clear during the study period. Epiphytic algae identified were recorded from 4 main divisions, namely Bacillariophyta, Chlorophyta, Cyanophyta and Euglenophyta. The highest algal diversity in Ndongo was recorded from Commelina benghalensis (H=3.45) with 41 algal species identified. Justicia in Ndongo river had the lowest algal species richness (24) with an algal diversity of 2.91. Nymphaea had the highest algal diversity (H=3.36) and algal species richness (36) in Limbe river. Algal species richness was the same in the two other plant hosts Commelina benghalensis and Colocasia esculentus (29 species per host). The highest algal chlorophyll a was recorded on Nymphaea (621mg/g dry weight) and Commelina benghalensis (644mg/g) in Limbe and Ndongo respectively. Lowest epiphyte Chlorophyll a was recorded in Justicia secunda in Ndongo (607 mg/g). Conclusion: All macrophytes studied harbored a large algal flora demonstrating their diverse ecological roles carried out in these rivers. Nymphaea lotus and Commelina benghalensis in Limbe and Ndongo rivers had the highest epiphytic algal biomass.

The effect of habitat on benthic diatoms in subarctic ponds – differences between rock and sediment

Subarctic ecosystems represent a vulnerable environment for their biota and studying their habitats provides a better understanding of ongoing and accelerated environmental change. Literature suggests that habitat and environmental variables such as water chemistry jointly influence benthic algal species richness and assemblage composition. However, the combined effects of habitat and water chemistry on benthic algal communities are poorly understood especially in subarctic freshwaters. This study compared benthic diatom assemblages on rocks and on sediment and examined if environmental variables affect diatoms similarly in these habitats. A total of 20 subarctic ponds were sampled for diatoms on sediment and rock in summer 2022 in northern Fennoscandia. Differences in species richness and Pielou evenness between habitats were analysed by a paired Wilcoxon signed-rank test. The most significant environmental variables influencing diatom species richness were determined by generalized linear models. Differences in diatom assemblage compositions were analysed using non-metric multidimensional scaling, analysis of similarities, and Jaccard similarity index. Finally, to study how environmental variables shape diatom compositions on rock and sediment, a redundancy analysis was performed. According to our results species richness and evenness were significantly higher on sediment than on rock, and water pH was the major determinant for diatom richness in both habitats. Diatom assemblage composition did not differ between rocks and sediment, and composition was shaped by the same environmental variables such as pond surface area and water pH in both habitats. Our results support the prevailing conception that sediment habitat contains higher diatom species richness than rocks, while assemblage composition does not differ between these habitats. This study highlights the role of water pH on benthic diatoms regardless of their habitat. Given that global warming is expected to affect water pH levels, such a change will probably have a notable influence also on subarctic diatom communities in the future decades.

Habitat attributes mediate herbivory and influence community development in algal metacommunities.

Understanding the drivers and impacts of spatiotemporal variation in species abundance on community trajectories is key to understanding the factors contributing to ecosystem resilience. Temporal variation in species trajectories across patches can provide compensation for species loss and can influence successional patterns. However, little is known about the underlying mechanisms that lead to patterns of species or spatial compensation and how those patterns may be mediated by consumer-resource relationships. Here we describe an experiment testing whether habitat attributes (e.g., structural complexity and spatial heterogeneity) mediate the effects of herbivory on tropical marine macroalgal communities by reducing accessibility and detectability, respectively, leading to variable trajectories among algal species at community (within patch) and metacommunity (i.e., among patch) scales. Reduced accessibility (greater habitat complexity) decreased the effects of herbivory (i.e., depressed consumption rate, increased algal species richness), and both accessibility and detectability (spatial heterogeneity) influenced algal community structure. Moreover, decreased accessibility at the community scale and a mosaic of accessibility at the metacommunity scale led to variation in community assembly. We suggest that habitat attributes can be important influencers of consumer-resource interactions on coral reefs, which in turn can increase species diversity, promote species succession, and enhance stability in algal metacommunities.

Phyllosphere eukaryotic microalgal communities in rainforests: Drivers and diversity

Phyllosphere algae are common in tropical rainforests, forming visible biofilms or spots on plant leaf surfaces. However, knowledge of phyllosphere algal diversity and the environmental factors that drive that diversity is limited. The aim of this study is to identify the environmental factors that drive phyllosphere algal community composition and diversity in rainforests. For this purpose, we used single molecule real-time sequencing of full-length 18S rDNA to characterize the composition of phyllosphere microalgal communities growing on four host tree species (Ficus tikoua, Caryota mitis, Arenga pinnata, and Musa acuminata) common to three types of forest over four months at the Xishuangbanna Tropical Botanical Garden, Yunnan Province, China. Environmental 18S rDNA sequences revealed that the green algae orders Watanabeales and Trentepohliales were dominant in almost all algal communities and that phyllosphere algal species richness and biomass were lower in planted forest than in primeval and reserve rainforest. In addition, algal community composition differed significantly between planted forest and primeval rainforest. We also found that algal communities were affected by soluble reactive phosphorous, total nitrogen, and ammonium contents. Our findings indicate that algal community structure is significantly related to forest type and host tree species. Furthermore, this study is the first to identify environmental factors that affect phyllosphere algal communities, significantly contributing to future taxonomic research, especially for the green algae orders Watanabeales and Trentepohliales. This research also serves as an important reference for molecular diversity analysis of algae in other specific habitats, such as epiphytic algae and soil algae.

Fairy ring disease affects epiphytic algal assemblages associated with the moss Sanionia uncinata (Hedw.) Loeske (Bryophyta) on King George Island, Antarctica.

Since the nineteenth century, a ring-forming disease attacking Antarctic mosses has been reported. However, to date, only the effects on the mosses themselves are known. In this study, we used DNA metabarcoding to investigate the effects on the moss epiphytic algal community at different stages of disease progression. As the disease progressed, algal species richness decreased, although overall abundance was not significantly affected. Prasiolales appeared unaffected, whereas Ulotrichales were more sensitive. Trebouxiales dominated the advanced disease stage, suggesting a possible benefit from the disease, either through the elimination of competition or creation of new niches. Infection is responsible for moss death, leading to habitat loss for other organisms, but pathogenic effects on algae cannot be ruled out. Our data indicate that the disease not only impacts mosses but also other groups, potentially resulting in loss of Antarctic biodiversity. This study provides the first report of the disease effects on epiphytic algal communities of Antarctic bryophytes.

Bioblitz Assessment of Rocky Intertidal Biodiversity within the Boston Harbor Islands National Recreation Area

Bioblitzes are rapid assessments of local biodiversity that provide opportunities for science, outreach, and management. Here, we present results from a bioblitz motivated by the National Park Service All Taxa Biodiversity Inventory to catalog species diversity in the rocky intertidal zones of the Boston Harbor Islands National Recreation Area. Through a combination of structured, quantitative surveys and opportunistic sampling, public participants, experienced scientists, and naturalists worked together to identify more than 130 species in the rocky intertidal zones of 8 of the Boston Harbor Islands. Sampling by experts alone yielded greater diversity than sampling conducted in collaboration with public participants. However, quantitative, structured sampling by expert-only and collaborative expert–public teams both revealed the expected negative relationship between algal species richness and intertidal elevation, suggesting that, with structure, public bioblitzes can feasibly document ecological patterns. We discuss these results in the context of rocky intertidal ecology, island biogeography, and the role of technology in the growing popularity of bioblitzes as a tool for collaborative engagement of scientists and the public in the study and management of natural systems.

Crustacean diversity in the Puget Sound: reconciling species, phylogenetic, and functional diversity

Biodiversity has critical phylogenetic and functional components, yet many prior studies of marine communities focus only on taxonomic diversity. Here, we surveyed intertidal crustacean communities across 11 sites in the Puget Sound (Washington state). We calculated taxonomic diversity (Shannon’s H), functional diversity (functional evenness and Rao’s Q), and phylogenetic diversity to examine how these indices were related and how they varied with environmental factors. A model selection approach (AIC) was used to examine which factors (habitat complexity, algal richness, salinity, and urbanization) were the best predictors for each index. Across sites, all four diversity indices were moderately correlated. Algal richness emerged as an important factor, occurring in well-supported models across all diversity indices: sites with more algal species had higher levels of taxonomic, functional, and phylogenetic diversity. Species diversity of both herbivores and non-herbivores was positively correlated with algal species richness, suggesting algae may be important for habitat as well as a food source. More species-rich algal communities had more phylogenetically diverse assemblages of herbivores, but algal richness was not correlated to non-herbivore phylogenetic diversity. Boulder size, but not other measures of habitat complexity, was positively correlated with functional diversity; most diversity in our samples was associated with boulders. Sites adjacent to higher levels of impervious surfaces (e.g., urbanization) had lower values of functional evenness. A growing number of studies have demonstrated that anthropogenic factors can have particularly strong effects on functional or phylogenetic diversity, and our study provides a number of tools for future investigations of crustacean diversity in this region.

Study of the algae flora of the Orenburg region: history and modernity

The article deals with the history of studying the species richness of algae in the Orenburg region from the first publications of the early nineteenth century to the present.

Post-fire redistribution of 137Cs and algal communities in contaminated forest soils in Belarus

This study was carried out in the forest area of the Gomel region of Belarus contaminated by 137Cs following the Chernobyl accident of 1986. The aim of the study was to explore the effects of different types of wildfires on the biological availability of radionuclides and the distribution of algal communities in fire-affected soils. Soil samples were collected in 2017 and 2018 from sites burnt by surface and crown fires, and from two unburnt reference locations. The soil samples were analyzed for radioactivity, agrochemical characteristics and the abundance of photoautotrophs. The proportions of various 137Cs fractions, according to our findings, differ between fire-affected and unburnt forest soils, and also between the different types of wildfire. The forest soil affected by surface fire is characterized by an increased amount of easily exchangeable and mobile fractions. In the forest burnt by the crown fire, where the above ground vegetation was almost completely destroyed, the mobile fractions of 137Cs are easily washed out from the topsoil, allowing them to penetrate into deeper soil layers. Soil algae play an important ecological role in sustaining terrestrial ecosystems and are sensitive to various physicochemical properties of soil, such as pH level, nutrient content and moisture. Most of these physicochemical properties are known to stimulate the growth of algal cells, however no evidence has been found in this study regarding the relationship between 137Cs activities in soil and the algal species richness.

Comparison of taxonomic composition of phytoplankton of the floodplain lakes of the buffer zone of the Prisursky State Nature Reserve

The data on the phytoplankton composition in the floodplain lakes of the Prisursky State Nature Reserve buffer zone in summer are presented for the first time. During two years of study, 219 taxa of algae (rank below genus) were registered in the phytoplankton. The representatives of the phyla Chlorophyta, Cyanophyta, and Euglenophyta played a dominant role. The larger the lake area, the highest was the species richness of algae. The algal planktonic flora of the lakes characterized by a high species richness had the highest similarity. In small water bodies, specific phytoplankton communities were developed.

Kelp patch size and density influence secondary productivity and diversity of epifauna

Habitat‐forming ecosystem engineers are the foundation of many marine ecosystems where they support diverse and productive food‐webs. A reduction in their patch size or density may affect the productivity, biodiversity and stability of these ecosystems. We determined the effects of different densities and patch sizes of Ecklonia radiata (the dominant kelp in southern Australia) on the secondary productivity, species richness, diversity and community structure of understory epifaunal invertebrates and how associated environmental covariates modified by kelp affected those patterns. We assessed sub‐canopy epifauna across 28 artificial reefs with transplanted E. radiata consisting of seven different patch sizes (0.12–7.68 m2) crossed with four kelp densities (0–16 kelp m−2) over two years. Epifaunal secondary productivity associated with both natural algal and standardised rope fibre habitats decreased with patch size and was elevated when kelp was absent, however, it was also high in natural habitat when there was a high density of kelp. Epifaunal productivity was positively associated with sub‐canopy light and water flow but negatively associated with the biomass of the dominant understory alga, Ulva sp. Epifaunal diversity declined with a reduction in reef size as did richness which correlated with a loss of algal species richness. Community structure of epifauna also differed between small and large reefs, between reefs with and without kelp, between rope habitats at the centre and at the edge of reefs, and within natural habitat between reefs supporting high and low densities of kelp. Overall, these results indicate complex effects of E. radiata decline on epifaunal communities, with high secondary productivity associated with dense kelp stands, but also areas without kelp that are dominated by turf algae. While the loss of standing kelp from rocky reefs may result in declines in epifaunal biodiversity, where turf algae replaces kelp, the reefs may still support high secondary productivity.

Biodiversity and thermal ecological function: The influence of freshwater algal diversity on local thermal environments.

The influence of temperature on diversity and ecosystem functioning is well studied; the converse however, that is, how biodiversity influences temperature, much less so. We manipulated freshwater algal species diversity in microbial microcosms to uncover how diversity influenced primary production, which is well documented in biodiversity research. We then also explored how visible‐spectrum absorbance and the local thermal environment responded to biodiversity change. Variations in the local thermal environment, that is, in the temperature of the immediate surroundings of a community, are known to matter not only for the rate of ecosystem processes, but also for persistence of species assemblages and the very relationship between biodiversity and ecosystem functioning. In our microcosm experiment, we found a significant positive association between algal species richness and primary production, a negative association between primary production and visible‐spectrum absorbance, and a positive association between visible‐spectrum absorbance and the response of the local thermal environment (i.e., change in thermal infrared emittance over a unit time). These findings support an indirect effect of algal diversity on the local thermal environment pointing to a hitherto unrecognized biodiversity effect in which diversity has a predictable influence on local thermal environments.

Green and Charophyte Algae in Bioindication of Water Quality of the Shah Alam River (District Peshawar, Pakistan)

Abstract 58 species and infraspecies of Chlorophyta and Charophyta algae were observed in 60 samples collected in September 2017 from the Shah Alam River, Pakistan. The algal species richness and environmental variables increased down the river, except for pH. Bioindication revealed low saline, low alkaline, middle streaming, and middle oxygenated water with low to middle organic pollution with Index saprobity S 1.48-1.73, Class 2-3 of Water Quality. The trophic state was eutrophic and meso-eutrophic with increasing eutrophication down the river. River Pollution Indices RPI demonstrated increasing of pollution in the Shah Alam River in comparison with the parallel part of the Kabul River.

Development and evaluation of a Planktonic Integrity Index (PII) for Jingpo Lake, China

A Planktonic Integrity Index (PII) for the China’s largest alpine barrier lake (Jingpo Lake) was developed to assess the water quality of Jingpo Lake by using phytoplankton and zooplankton metrics. Phytoplankton and zooplankton assemblages were sampled at 26 sites in Jingpo Lake. A total of 140 species of phytoplankton and 92 species of zooplankton were obtained in the investigations. We used a stepwise process to evaluate properties of candidate metrics and selected five for the PII: Algal cell abundance, Species richness of algae, Trophic diatom index, Zooplankton Shannon index, and Zooplankton Margalef index. Evaluation of the PII showed that it discriminated well between reference and impaired sites and the discriminatory biocriteria of the PII were suitable for the assessment of the water quality of Jingpo Lake. The further scoring results from the 26 sites showed that the water quality of Jingpo Lake was fair to good. The results of analyses between PII and major environmental factors indicated that water temperature (WT), transparency (SD), dissolved oxygen (DO), potassium permanganate (CODMn) and total nitrogen (TN) were the main factors influencing on the composition and distribution of phytoplankton and zooplankton. Additionally, more metrics belonging to habitat, hydrology, physics and chemistry should be considered for the PII, so as to establish comprehensive assessment system which can reflect the community structure of aquatic organisms, physical and chemical characteristics of water environment, human activities, etc.

Responses of periphyton on non-plant substrates to different macrophytes under various nitrogen concentrations: A mesocosm study

Periphyton in aquatic ecosystems is comprised of algae, heterotrophic microbes, and detritus. In shallow lakes, periphyton is affected by substrate type, nutrient supply, and other factors. Periphyton on macrophytes can interact strongly with the host, but whether different periphyton on non-plant substrates are affected by nearby submerged macrophytes is unclear. We conducted a six-month mesocosm study to investigate the responses of periphyton (on sand, cobblestone, or plastic) to different nitrogen concentrations (i.e., 10 mg L−1 ammonia, 10 mg L−1 nitrate, or no addition) in the presence of different macrophyte species (i.e., Vallisneria spinulosa, Potamogeton wrightii, and Potamogeton maackianus). Periphytic pigment content (chlorophyll and pheophytin), nutrient accrual (carbon, nitrogen, and phosphorus), carbon:chlorophyll ratio, and algal species composition were determined at the end of the experiment. Results showed that substrate type was critical for all periphyton parameters. Periphytic nutrient accrual and the carbon:chlorophyll ratio were both higher on sand than on the other two substrates. Nitrogen concentrations had a considerable effect on periphytic chlorophyll-a, nitrogen, and phosphorus accrual. In particular, the addition of ammonia (but not nitrate) led to significantly higher periphytic chlorophyll-a than the treatment without nitrogen. Furthermore, periphytic algal species richness and diversity were lower in the presence of P. wrightii than in the presence of the other macrophyte species. Thus, in addition to the importance of substrate type and nitrogen concentration, the species composition of nearby submerged macrophytes could potentially influence the periphyton community on a non-plant substrate.

Impact of the invasive species Sargassum muticum (Phaeophyta) on tide pool macroalgal assemblages of northern Spain

The impact of the invasive seaweed Sargassum muticum (Yendo) Fensholt (Phaeophyta, Sargassaceae) on tide pool macroalgal assemblages of northern Spain was investigated between 2001 and 2004. Invader removal experiments were simultaneously conducted at three semi-exposed rocky-shores within a shoreline length of 200 km. Changes in the abundance of algal functional-form groups, species richness and diversity were compared between manipulated and control rock pools. Leathery macrophytes, especially Bifurcaria bifurcata, slightly increased following removal of S. muticum at 2 of the 3 studied localities. The remaining functional-form groups, diversity and species richness did not appear to be affected. Because of the heterogeneous distribution of S. muticum in northern Spain, the overall effect of the species is likely to be minimal both among localities and among pools within a locality.

Biodiversity influences invasion success of a facultative epiphytic seaweed in a marine forest

The biotic resistance hypothesis predicts that more diverse communities should have greater resistance to invasions than species-poor communities. However for facultative and obligate epiphytic invaders a high native species richness, abundance and community complexity might provide more resources for the invader to thrive to. We conducted surveys across space and time to test for the influence of native algal species abundance and richness on the abundance of the invasive facultative epiphytic filamentous alga Lophocladia lallemandii in a Mediterranean Cystoseira balearica seaweed forest. By removing different functional groups of algae, we also tested whether these relationships were dependent on the complexity and abundance of the native algal community. When invasion was first detected, Lophocladia abundance was positively related to species richness, but the correlation became negative after two years of invasion. Similarly, a negative relationship was also observed across sites. The removal experiment revealed that more complex native communities were more heavily invaded, where also a positive relationship was found between native algal richness and Lophocladia, independently of the native algal abundance. Our observational and experimental data show that, at early stages of invasion, species-rich seaweed forests are not more resistant to invasion than species-poor communities. Higher richness of native algal species may increase resource availability (i.e. substrate) for invader establishment, thus facilitating invasion. After the initial invasion stage, native species richness decreases with time since invasion, suggesting negative impacts of invasive species on native biodiversity.

Heterogeneity in Nitrogen Sources Enhances Productivity and Nutrient Use Efficiency in Algal Polycultures.

Algae hold much promise as a potential feedstock for biofuels and other products, but scaling up biomass production remains challenging. We hypothesized that multispecies assemblages, or polycultures, could improve crop yield when grown in media with mixed nitrogen sources, as found in wastewater. We grew mono- and poly- cultures of algae in four distinct growth media that differed in the form (i.e., nitrate, ammonium, urea, plus a mixture of all three) but not the concentration of nitrogen. We found that mean biomass productivity was positively correlated with algal species richness, and that this relationship was strongest in mixed nitrogen media (on average 88% greater biomass production in 5-species polycultures than in monocultures in mixed nitrogen treatment). We also found that the relationship between nutrient use efficiency and species richness was positive across nitrogen treatments, but greatest in mixed nitrogen media. While polycultures outperformed the most productive monoculture only 0-14% of the time in this experiment, they outperformed the average monoculture 26-52% of the time. Our results suggest that algal polycultures have the potential to be highly productive, and can be effective in recycling nutrients and treating wastewater, offering a sustainable and cost-effective solution for biofuel production.

Use of soil biota in the assessment of the ecological potential of urban soils

In assessing the ecological conditions and classification of urban soils, data about soil biota should be taken into account. The environment of urban territories is characterized by significant changes compared to their surrounding environments. It is established that the algal flora of urban soils lose their zonal features and features associated with the edification influence of higher plants. Specific biotopes with a definite species structure are formed in urboecosystems. Fifty 50 algae species have been recorded in the soils of the Henichesk urboecosystems (Kherson region, Ukraine): Cyanoprocaryota – 21, Chlorophyta – 13, Charophyta – 2, Eustigmatophyta – 1, Xanthophyta – 11, Bacillariophyta – 2. Among dominant and subdominant species were Cyanoprocaryota and Chlorophyta. The other phyla were represented by Klebsormidium dissectum, K. flaccidum, Hantzschia amphioxys, Eustigmatos magnus, Botrydiopsis eriensis. Compared with the surrounding environment, the urbanized flora of Henichesk has a low species richness, and is characterized by prevalence of Cyanoprocaryota and Chlorophyta species. The coefficient that takes into account the percentage of preservation of species richness in a particular urban area compared to the background indicators of species richness can be used to evaluate the urban transformation of soil biota. The degree of degradatory changes in the composition of living organisms and the direction of these changes depends on the specificity and intensity of exploitation of the territory of the urban ecosystem. The most diverse composition of algae species within the the city of Henichesk was noted in the recreational, residential, and transport zones, in comparison with the industrial zone and the zone of special use. Different functional areas of the city are distinguished not only by the algae species richness, but also by the composition of dominants. Among the dominants and subdominants of the recreational and transport zones were species of different phyla. The dominants and subdominants of the residential and industrial zones were Cyanoprocaryota species, in the zone of special use – representatives of Chlorophyta. The distribution of species richness of algae along the soil profile in the city acquires an atypical character. The species richness increases not in the most superficial layers of soil, but in the lower, aphotic parts of the soil profile. The soil biota, on the one hand, depends on the ecological conditions of soil, and on the other as a result of its life activity, changes the ecological functions of the soil, strengthening or weakening them. The reduction in the species richness of the soil algae of the urboecosystem Henichesk shows the limitations of ecological functions of urban soils. It is established that changes in the composition of algae in soils of urban ecosystems are one of the indicators of the presence and severity of transformation processes. These processes occur with the soil biota and soil as a whole under the conditions of urban ecosystems and can be used as indicators in the environmental assessment of urban soils, in the development and subsequent examination of ways to reduce negative expression of urbanization.

Main predictors of periphyton species richness depend on adherence strategy and cell size.

Periphytic algae are important components of aquatic ecosystems. However, the factors driving periphyton species richness variation remain largely unexplored. Here, we used data from a subtropical floodplain (Upper Paraná River floodplain, Brazil) to quantify the influence of environmental variables (total suspended matter, temperature, conductivity, nutrient concentrations, hydrology, phytoplankton biomass, phytoplankton species richness, aquatic macrophyte species richness and zooplankton density) on overall periphytic algal species richness and on the richness of different algal groups defined by morphological traits (cell size and adherence strategy). We expected that the coefficients of determination of the models estimated for different trait-based groups would be higher than the model coefficient of determination of the entire algal community. We also expected that the relative importance of explanatory variables in predicting species richness would differ among algal groups. The coefficient of determination for the model used to predict overall periphytic algal species richness was higher than the ones obtained for models used to predict the species richness of the different groups. Thus, our first prediction was not supported. Species richness of aquatic macrophytes was the main predictor of periphyton species richness of the entire community and a significant predictor of the species richness of small mobile, large mobile and small-loosely attached algae. Abiotic variables, phytoplankton species richness, chlorophyll-a concentration, and hydrology were also significant predictors, depending on the group. These results suggest that habitat heterogeneity (as proxied by aquatic macrophytes richness) is important for maintaining periphyton species richness in floodplain environments. However, other factors played a role, suggesting that the analysis of species richness of different trait-based groups unveils relationships that were not detectable when the entire community was analysed together.