Tropical aquatic fungi

This paper reports on the distribution of fungal communities in aquatic habitats in tropical regions and highlights differences in the taxa observed in freshwater and marine habitats. Ascomycetes are dominant on substrata in marine environments, with few basidiomycetes and discomycetes. Equally, few freshwater basidiomycetes and discomycetes have been reported from the tropics. In marine habitats, Dothideomycetes dominate on mangrove substrata, and halosphaeriaceous species are most numerous on submerged woody substrata in coastal waters, while yeasts are common in seawater and estuarine habitats. In freshwater, Ingoldian anamorphic fungi are most numerous on decaying leaves, while ascomycetes (Dothideomycetes, Sordariomycetes) are prevalent on submerged/exposed woody substrata. Unique fungi are found in tropical waters and differ from those in temperate locations.     

Diversity and abundance of nematode-trapping fungi from decaying litter in terrestrial, freshwater and mangrove habitats

Nematode-trapping fungi are ubiquitous in terrestrial habitats in dung, soils, litter and woody debris and they also occur in freshwater, but only one species has been found in marine habitats. The purpose of this study was therefore to investigate whether nematode-trapping fungi occurred in mangrove habitats. To achieve this we assessed the diversity of nematode-trapping fungi on decaying litter from mangroves, freshwater and terrestrial habitats (22 sites) in Hong Kong. Composite samples (n = 1,320) of decaying litter (wood and leaves) were examined and a total of 31 species of nematode-trapping fungi belonging to four genera, Arthrobotrys, Monacrosporium, and Dactylella were recorded. Twenty-nine species reported in this study are new records for Hong Kong and 16 species are new records from mangrove habitats worldwide. Nematode trapping fungi are therefore present in marine environments. Commonly encountered taxa were Arthrobotrys oligospora and Monacrosporium thaumasium which are abundant in all habitats. A. oligospora, M. thaumasium and Arthrobotrys musiformis were frequent (F > 10%). Twenty-six species were rare (0.16–9.32%). Species richness and diversity was higher in terrestrial than in freshwater and mangrove habitats (ANOVA, P < 0.001). A higher mean diversity was observed on decaying leaves as compared to decaying wood in all habitats (P < 0.001). Based on Shannon diversity index, it was also observed that taxa characterized by adhesive nets were more frequent in all habitats. This can be explained by the fact that these taxa may have a better competitive saprotrophic ability which would allow them to compete favourably in nutrient limited environments. Abiotic factors that could be linked to differences in species diversity between decaying wood and leaves are also discussed.     

Biodiversity and Enzyme Activity of Marine Fungi with 28 New Records from the Tropical Coastal Ecosystems in Vietnam

The coastal marine ecosystems of Vietnam are one of the global biodiversity hotspots, but the biodiversity of marine fungi is not well known. To fill this major gap of knowledge, we assessed the genetic diversity (ITS sequence) of 75 fungal strains isolated from 11 surface coastal marine and deeper waters in Nha Trang Bay and Van Phong Bay using a culture-dependent approach and 5 OTUs (Operational Taxonomic Units) of fungi in three representative sampling sites using next-generation sequencing. The results from both approaches shared similar fungal taxonomy to the most abundant phylum (Ascomycota), genera (Candida and Aspergillus) and species (Candida blankii) but were different at less common taxa. Culturable fungal strains in this study belong to 3 phyla, 5 subdivisions, 7 classes, 12 orders, 17 families, 22 genera and at least 40 species, of which 29 species have been identified and several species are likely novel. Among identified species, 12 and 28 are new records in global and Vietnamese marine areas, respectively. The analysis of enzyme activity and the checklist of trophic mode and guild assignment provided valuable additional biological information and suggested the ecological function of planktonic fungi in the marine food web. This is the largest dataset of marine fungal biodiversity on morphology, phylogeny and enzyme activity in the tropical coastal ecosystems of Vietnam and Southeast Asia. Biogeographic aspects, ecological factors and human impact may structure mycoplankton communities in such aquatic habitats.     

Unravelling the taxonomy and identification of a problematic group of benthic fishes from tropical rivers (Gobiidae: Glossogobius)

Flathead gobies (genus Glossogobius) include c. 40 small- to medium-sized benthic fishes found primarily in freshwater habitats across the Indo-Pacific, having biodiversity value as well as cultural and economic value as food fishes, especially in developing countries. To help resolve considerable confusion regarding the identification of some of the larger-growing Glossogobius species, a systematic framework was established using nuclear genetic markers, mitochondrial DNA barcoding and phenotypic evidence for a geographically widespread collection of individuals from the waterways of tropical northern Australia. Species boundaries and distribution patterns were discordant with those previously reported, most notably for the tank goby Glossogobius giuris, which included a cryptic species. Genetic divergence was matched with accompanying unique visual characters that aid field identification. Additional taxonomic complexity was also evident, by comparison with DNA barcodes from international locations, suggesting that the specific names applicable for two of the candidate species in Australia remain unresolved due to confusion surrounding type specimens. Although flathead gobies are assumed to be widespread and common, this study demonstrates that unrealised taxonomic and ecological complexity is evident, and this will influence assessments of tropical biodiversity and species conservation. This study supports the need for taxonomic studies of freshwater fishes to underpin management in areas subject to significant environmental change.     

Influence of salinity on bacterioplankton communities from the Brazilian rain forest to the coastal Atlantic Ocean

Background

Planktonic bacteria are recognized as important drivers of biogeochemical processes in all aquatic ecosystems, however, the taxa that make up these communities are poorly known. The aim of this study was to investigate bacterial communities in aquatic ecosystems at Ilha Grande, Rio de Janeiro, Brazil, a preserved insular environment of the Atlantic rain forest and how they correlate with a salinity gradient going from terrestrial aquatic habitats to the coastal Atlantic Ocean.

Methodology/Principal Findings

We analyzed chemical and microbiological parameters of water samples and constructed 16S rRNA gene libraries of free living bacteria obtained at three marine (two coastal and one offshore) and three freshwater (water spring, river, and mangrove) environments. A total of 836 sequences were analyzed by MOTHUR, yielding 269 freshwater and 219 marine operational taxonomic units (OTUs) grouped at 97% stringency. Richness and diversity indexes indicated that freshwater environments were the most diverse, especially the water spring. The main bacterial group in freshwater environments was Betaproteobacteria (43.5%), whereas Cyanobacteria (30.5%), Alphaproteobacteria (25.5%), and Gammaproteobacteria (26.3%) dominated the marine ones. Venn diagram showed no overlap between marine and freshwater OTUs at 97% stringency. LIBSHUFF statistics and PCA analysis revealed marked differences between the freshwater and marine libraries suggesting the importance of salinity as a driver of community composition in this habitat. The phylogenetic analysis of marine and freshwater libraries showed that the differences in community composition are consistent.

Conclusions/Significance

Our data supports the notion that a divergent evolutionary scenario is driving community composition in the studied habitats. This work also improves the comprehension of microbial community dynamics in tropical waters and how they are structured in relation to physicochemical parameters. Furthermore, this paper reveals for the first time the pristine bacterioplankton communities in a tropical island at the South Atlantic Ocean.     

Phylogeny of Chaetonotidae and other Paucitubulatina (Gastrotricha: Chaetonotida) and the colonization of aquatic ecosystems

Kånneby, T., Todaro, M. A., Jondelius, U. (2012). Phylogeny of Chaetonotidae and other Paucitubulatina (Gastrotricha: Chaetonotida) and the colonization of aquatic ecosystems. —Zoologica Scripta, 42, 88–105. Chaetonotidae is the largest family within Gastrotricha with almost 400 nominal species represented in both freshwater and marine habitats. The group is probably non‐monophyletic and suffers from a troubled taxonomy. Current classification is to a great extent based on shape and distribution of cuticular structures, characters that are highly variable. We present the most densely sampled molecular study so far where 17 of the 31 genera belonging to Chaetonotida are represented. Bayesian and maximum likelihood approaches based on 18S rDNA, 28S rDNA and COI mtDNA are used to reconstruct relationships within Chaetonotidae. The use of cuticular structures for supra‐specific classification within the group is evaluated and the question of dispersal between marine and freshwater habitats is addressed. Moreover, the subgeneric classification of Chaetonotus is tested in a phylogenetic context. Our results show high support for a clade containing Dasydytidae nested within Chaetonotidae. Within this clade, only three genera are monophyletic following current classification. Genera containing both marine and freshwater species never form monophyletic clades and group with other species according to habitat. Marine members of Aspidiophorus appear to be the sister group of all other Chaetonotidae and Dasydytidae, indicating a marine origin of the clade. Halichaetonotus and marine Heterolepidoderma form a monophyletic group in a sister group relationship to freshwater species, pointing towards a secondary invasion of marine environments of these taxa. Our study highlights the problems of current classification based on cuticular structures, characters that show homoplasy for deeper relationships.     

Morphometric convergence among European sand gobies in freshwater (Gobiiformes: Gobionellidae)

The five genera of sand gobies inhabit the seas and freshwaters of Europe and western Asia and occupy habitats ranging from fully marine to exclusively freshwater. In this study, we use geometric morphometrics to quantify body shape among sand gobies, in order to investigate how shape has evolved and how it is related to habitat. We also compare body shape between preserved museum specimens and fresh specimens, to determine whether or not fixation and storage in ethanol introduce detectable bias. We confirm that the fixed specimens exhibit significant shape changes as compared to fresh specimens, and so, we perform the bulk of our analyses exclusively on fixed specimens. We find that Economidichthys, Orsinigobius, and Pomatoschistus occupy distinct regions of morphospace. Knipowitschia and Ninnigobius have intermediate forms that overlap with Pomatoschistus and Orsinigobius, but not Economidichthys. This pattern is also in rough accordance with their habitats: Pomatoschistus is fully marine, Economidichthys fully freshwater, and the others fresh with some brackish tolerance. We augment a recent phylogeny of sand gobies with data for P. quagga and interpret morphometric shape change on that tree. We then evaluate convergence in form among disparate lineages of freshwater species by constructing a phylomorphospace and applying pattern‐based (convevol) measures of convergence. We find that freshwater taxa occupy a mostly separate region of morphospace from marine taxa and exhibit significant convergence in form. Freshwater taxa are characterized by relatively larger heads and stockier bodies than their marine relatives, potentially due to a common pattern of heterochronic size reduction.     

Fungi populate deep-sea coral gardens as well as marine sediments in the Irish Atlantic Ocean

Fungi populate deep Oceans in extreme habitats characterized by high hydrostatic pressure, low temperature and absence of sunlight. Marine fungi are potential major contributors to biogeochemical events, critical for marine communities and food web equilibrium under climate change conditions and a valuable source of novel extremozymes and small molecules. Despite their ecophysiological and biotechnological relevance, fungal deep-sea biodiversity has not yet been thoroughly characterized. In this study, we describe the culturable mycobiota associated with the deepest margin of the European Western Continental Shelf: sediments sampled at the Porcupine Bank and deep-water corals and sponges sampled in the Whittard Canyon. Eighty-seven strains were isolated, belonging to 43 taxa and mainly Ascomycota. Ten species and four genera were detected for the first time in the marine environment and a possible new species of Arachnomyces was isolated from sediments. The genera Cladosporium and Penicillium were the most frequent and detected on both substrates, followed by Candida and Emericellopsis. Our results showed two different fungal communities: sediment-associated taxa which were predominantly saprotrophic and animal-associated taxa which were predominantly symbiotic. This survey supports selective fungal biodiversity in the deep North Atlantic, encouraging further mycological studies on cold water coral gardens, often overexploited marine habitats.     

Anamorphic fungi from freshwater habitats in China: Dictyosporium tetrasporum and Exserticlava yunnanensis spp. nov., and two new records for Pseudofuscophialis lignicola and Pseudobotrytis terrestris

This article describes two new anamorphic fungi from freshwater habitats, Dictyosporium tetrasporum sp. nov. and Exserticlava yunnanensis sp. nov., based on morphological characters. Both species are illustrated with light micrographs and compared with similar taxa. Pseudofuscophialis lignicola and Pseudobotrytis terrestris are reported as new records from freshwater habitats.     

A fine-scale gap analysis of the existing protected area system in Hong Kong, China

As well as being one of the most densely populated areas on Earth, Hong Kong also has the highest percentage of protected areas (38% of the 1098 km² land area) of any administrative region in the Asia Pacific. Overlay of field records from a biodiversity survey of eight taxa (amphibians, reptiles, mammals, breeding birds, ants, butterflies, dragonflies and rare vascular plants) in 1 km grid squares with protected areas indicated that over half of the 623 species of conservation concern (globally, regionally, or locally restricted species) were under-represented. Ants, butterflies and reptiles were most poorly represented. The hotspots of different taxa also received differing levels of protection. Hong Kong's protected areas are biased towards high-altitude habitats, so the under-represented species are mostly associated with the lowland habitats (freshwater wetlands, abandoned agriculture and feng shui woods). Since the restricted species are scattered and the hotspots of different taxa do not overlap, a large protected area network will be required to represent all species. This indicates the challenge that will be encountered in the conservation of many other parts of Asia that support burgeoning human populations, and where landscapes are increasingly human-dominated.     

Latitudinal, habitat and substrate distribution patterns of freshwater ascomycetes in the Florida Peninsula

Freshwater ascomycetes are important decomposers of dead woody and herbaceous debris in aquatic habitats. Despite evidence of their ecological importance, latitudinal, habitat and substrate distributional patterns of freshwater ascomycetes are poorly understood. In this study, we examined the latitudinal and habitat distributional patterns, and substrate recurrences of freshwater ascomycetes by collecting dead submerged woody and herbaceous debris in lentic and lotic habitats at five selected sites along a north-central-south, temperate–subtropical latitudinal ecotone in Florida. One hundred and thirty-two fungal taxa were collected during the study. Seventy-four were meiosporic and 56 were mitosporic ascomycetes, while two species were basidiomycetes. Canonical analyses of principal coordinates (CAP) and Sørenson’s similarity index of species based on presence/absence data revealed a high turnover in species composition between the northern and southern sites, indicating a change in species composition along the temperate–subtropical latitudinal ecotone of the Florida Peninsula. Results from the ordination analysis indicated that freshwater ascomycete community composition is not significantly different between lentic and lotic habitats in Florida. The geographically broadly distributed species and species commonly found in Florida occurred in both habitats, whereas a number of new or rare species occurred in either lentic or lotic habitats, but not both. The same freshwater ascomycete species did not necessarily occur on both woody and herbaceous debris; of the 132 taxa collected, 100 were reported only on woody debris; 14 species occurred exclusively on herbaceous debris; and 18 species were found on both woody and herbaceous debris in lentic or lotic habitats. Implications of data from this study to the conservation and knowledge of biodiversity for freshwater ascomycetes is discussed.     

Biogeography,habitat transitions and hybridization in a radiation of South American silverside fishes revealed by mitochondrial and genomic RAD data

Rivers and lake systems in the southern cone of South America have been widely influenced by historical glaciations, carrying important implications for the evolution of aquatic organisms, including prompting transitions between marine and freshwater habitats and by triggering hybridization among incipient species via waterway connectivity and stream capture events. Silverside fishes (Odontesthes) in the region comprise a radiation of 19 marine and freshwater species that have been hypothesized on the basis of morphological or mitochondrial DNA data to have either transitioned repeatedly into continental waters from the sea or colonized marine habitats following freshwater diversification. New double digest restriction‐site associated DNA data presented here provide a robust framework to investigate the biogeographical history of and habitat transitions in Odontesthes. We show that Odontesthes silversides originally diversified in the Pacific but independently colonized the Atlantic three times, producing three independent marine‐to‐freshwater transitions. Our results also indicate recent introgression of marine mitochondrial haplotypes into two freshwater clades, with more recurring instances of hybridization among Atlantic‐ versus Pacific‐slope species. In Pacific freshwater drainages, hybridization with a marine species appears to be geographically isolated and may be related to glaciation events. Substantial structural differences of estuarine gradients between these two geographical areas may have influenced the frequency, intensity and evolutionary effects of hybridization events.     

Taeniolella rudis and Taeniolella longissima sp. nov. with secondary sympodioconidia from freshwater habitats

 Taeniolella rudis, with secondary sympodioconidia, is illustrated and described and its taxonomic assignment evaluated. A second new species, Taeniolella longissima, is described and illustrated. The ecological role of these fungi in the colonization of wood in freshwater habitats is discussed. Received: August 16, 2001 / Accepted: February 8, 2002     

From Sea to Sea: Canada's Three Oceans of Biodiversity

Evaluating and understanding biodiversity in marine ecosystems are both necessary and challenging for conservation. This paper compiles and summarizes current knowledge of the diversity of marine taxa in Canada''s three oceans while recognizing that this compilation is incomplete and will change in the future. That Canada has the longest coastline in the world and incorporates distinctly different biogeographic provinces and ecoregions (e.g., temperate through ice-covered areas) constrains this analysis. The taxonomic groups presented here include microbes, phytoplankton, macroalgae, zooplankton, benthic infauna, fishes, and marine mammals. The minimum number of species or taxa compiled here is 15,988 for the three Canadian oceans. However, this number clearly underestimates in several ways the total number of taxa present. First, there are significant gaps in the published literature. Second, the diversity of many habitats has not been compiled for all taxonomic groups (e.g., intertidal rocky shores, deep sea), and data compilations are based on short-term, directed research programs or longer-term monitoring activities with limited spatial resolution. Third, the biodiversity of large organisms is well known, but this is not true of smaller organisms. Finally, the greatest constraint on this summary is the willingness and capacity of those who collected the data to make it available to those interested in biodiversity meta-analyses. Confirmation of identities and intercomparison of studies are also constrained by the disturbing rate of decline in the number of taxonomists and systematists specializing on marine taxa in Canada. This decline is mostly the result of retirements of current specialists and to a lack of training and employment opportunities for new ones. Considering the difficulties encountered in compiling an overview of biogeographic data and the diversity of species or taxa in Canada''s three oceans, this synthesis is intended to serve as a biodiversity baseline for a new program on marine biodiversity, the Canadian Healthy Ocean Network. A major effort needs to be undertaken to establish a complete baseline of Canadian marine biodiversity of all taxonomic groups, especially if we are to understand and conserve this part of Canada''s natural heritage.     

Global analysis reveals that cryptic diversity is linked with habitat but not mode of life

The ubiquity of genetically distinct, cryptic species is limiting any attempt to estimate local or global biodiversity as well as impeding efforts to conserve species or control pests and diseases. Environmental factors or biological traits promoting rapid diversification into morphologically similar species remain unclear. Here, using a meta‐analysis of 1230 studies using DNA sequences to search for cryptic diversity in metazoan taxa, we test two hypotheses regarding the frequency of cryptic taxa based on mode of life and habitat. First, after correcting for study effort and accounting for higher taxonomic affinities and biogeographical region of origins, our results do not support the hypothesis that cryptic taxa are more frequent among parasitic than free‐living taxa. Second, in contrast, the results support the hypothesis that cryptic taxa are more common in certain habitats than others: for a given study effort, more cryptic taxa are found in freshwater than in terrestrial or marine taxa. These findings suggest that the greater heterogeneity and fragmentation of freshwater habitats may promote higher rates of genetic differentiation among its inhabitants, a general pattern with serious implications for freshwater conservation biology.     

Diversity patterns of ground beetles and understory vegetation in mature,secondary, and plantation forest regions of temperate northern China

Plantation and secondary forests form increasingly important components of the global forest cover, but our current knowledge about their potential contribution to biodiversity conservation is limited. We surveyed understory plant and carabid species assemblages at three distinct regions in temperate northeastern China, dominated by mature forest (Changbaishan Nature Reserve, sampled in 2011 and 2012), secondary forest (Dongling Mountain, sampled in 2011 and 2012), and forest plantation habitats (Bashang Plateau, sampled in 2006 and 2007), respectively. The α‐diversity of both taxonomic groups was highest in plantation forests of the Bashang Plateau. Beetle α‐diversity was lowest, but plant and beetle species turnover peaked in the secondary forests of Dongling Mountain, while habitats in the Changbaishan Nature Reserve showed the lowest turnover rates for both taxa. Changbaishan Nature Reserve harbored the highest proportion of forest specialists. Our results suggest that in temperate regions of northern China, the protected larch plantation forest established over extensive areas might play a considerable role in maintaining a high biodiversity in relation to understory herbaceous plant species and carabid assemblages, which can be seen as indicators of forest disturbance. The high proportion of phytophagous carabids and the rarity of forest specialists reflect the relatively homogenous, immature status of the forest ecosystems on the Bashang Plateau. China's last remaining large old‐growth forests like the ones on Changbaishan represent stable, mature ecosystems which require particular conservation attention.     

A multigene molecular assessment of cryptic biodiversity in the iconic freshwater blackfishes (Teleostei: Percichthyidae: Gadopsis) of south‐eastern Australia

Freshwater biodiversity is under ever increasing threat from human activities, and its conservation and management require a sound knowledge of species‐level taxonomy. Cryptic biodiversity is a common feature for aquatic systems, particularly in Australia, where recent genetic assessments suggest that the actual number of freshwater fish species may be considerably higher than currently listed. The freshwater blackfishes (genus Gadopsis) are an iconic group in south‐eastern Australia and, in combination with their broad, naturally divided distribution and biological attributes that might limit dispersal, as well as ongoing taxonomic uncertainty, they comprise an ideal study group for assessing cryptic biodiversity. We used a multigene molecular assessment including both nuclear (51 allozyme loci; two S7 introns) and matrilineal markers (cytb) to assess species boundaries and broad genetic substructure within freshwater blackfishes. Range‐wide examination demonstrates the presence of at least six candidate species across two nominal taxa, Gadopsis marmoratus and Gadopsis bispinosus. Phylogeographical patterns often aligned to purported biogeographical provinces but occasionally reflected more restricted and unexpected relationships. We highlight key issues with taxonomy, conservation, and management for a species group in a highly modified region. © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 111 , 521–540.     

Open water zooplankton communities in North African wetland lakes: the CASSARINA Project

Zooplankton (Copepoda, Cladocera, Ostracoda, Rotifera and Diptera larvae) in nine North African lakes was collected from open water areas over twenty months during 1997/99. The results were used to monitor changes in the pelagic micro-invertebrate fauna of these sites with the purpose of exploring diversity structure and regional species occurrences.The studied sites formed three distinct groups based on hydrology and water quality criteria: (i) acid water with no marine connection (Megene Chitane); (ii) alkaline freshwater/brackish with no marine connection (Merja Sidi Bou Rhaba and Merja Bokka); (iii) freshwater/brackish with marine connection (Merja Zerga, Lac de Korba, Garaet El Ichkeul and three Nile Delta lakes). However, cluster analysis of the zooplankton data alone indicated four groups with Korba being separated because of its prevalence of species tolerant of summer hypersalinity.The total regional zooplanktonic species richness found was 88 taxa and these were characterized by species tolerant of widely fluctuating environmental conditions. However, some recorded species were very rare for North African freshwaters (e.g. Alonella excisa, Leydigia quadrangularis and, Ilyocryptus sordidus) and generally indicate favourable environmental conditions of low salinity and temperature. The sites influenced by marine waters generally exhibited slightly lower numbers of species but which generally demonstrate cosmopolitan distributions. Distinct seasonal patterns in species distributions were more similar to those observed in European lakes rather than to those of lower latitudes sites.Zooplankton play a key role in maintaining aquatic ecosystem quality in the North African study lakes and the community distributions described for the late 20th century help set biodiversity base-line data for future studies. If the remaining wetland lakes in this region are to persist as important resources during the 21st century, they will need to be managed in a way that ensures that aquatic diversity is maintained.     

Power law relationships among hierarchical taxonomic categories in algae reveal a new paradox of the plankton

Aim In this continental‐scale study, the biodiversity of benthic and planktonic algal communities was explored. A recent analysis of extinct and extant tree communities by Enquist et al. (2002) showed that richness of higher taxa was a power function of species richness, invariant across temporal and spatial scales. Here we examined whether the relationships between algal richness at hierarchical taxonomic levels conform to power laws as seen for trees, and if these relationships differ between benthic and planktonic habitats. Location Streams from more than 50 major watersheds in the United States. Method A total of 3698 samples were collected from 1277 locations by the National Water‐Quality Assessment Program. Three types of stream habitat were sampled: richest targeted habitats, depositional targeted habitats, and phytoplankton. The relationships between taxonomic richness at the species level vs. all higher categories from genus to phylum across the three habitats were examined by ordinary least squares (OLS) regressions after ln‐transformation of all variables. The slopes, b, of these regressions represent the exponents of the power functions that scaled the richness of higher taxonomic levels (T) to species richness (S) in the form: T∝S^b. Results Algal richness at hierarchical taxonomic categories (genus to phylum) is a power function of species richness. The scaling exponent of this function, which captures the diversification of higher taxa, i.e. the rate of increase of their richness with the increase of species richness, is significantly different across environments. Main conclusions The differential algal diversification in the three studied habitats emphasizes the fundamental role of the environment in structuring the communities of simple organisms such as algae. The finding that the diversification of higher taxa is greater in the seemingly homogeneous planktonic environment, when compared to benthic habitats, encompassing an array of ecological niches, poses a new paradox of the plankton.