Quantitative and qualitative variability of epiphytic algae on one Apiaceae (<Emphasis Type="Italic">Apium nodiflorum</Emphasis> L.) in a karstic river (Southeast of France)

Spatial distribution of the firmly attached epiphytic algae was investigated directly on the leaves of one Apiaceae (Apium nodiflorum L.) commonly found in chalky Mediterranean rivers, at two sampling dates (summer and autumn). The composition and structure of the epiphytic communities of the samples were determined at different levels: along the leaves, on both their sides and within each leaflet (n = 13). Forty-eight leaflets from four randomly selected plants were cut along the longitudinal and vertical axes so as to define 16 microhabitats located on the edge, the centre and the vein. Only a few species of algae were found to be constantly present whatever the sampling date, and dominated all microzones (n = 768). Their presence seemed to depend, rather, on the architectural structure of the plant. The other algae represented the major part of the epiphytic community and were only occasionally present. Those were more subject to temporal and environmental variations and less specific of the substrate. The epiphytes showed considerable spatial heterogeneity within their microhabitats, with an evident preference for the centre and the edge of the leaves, whereas two inhospitable spaces were the vein and apex. On the other hand, when the study was performed at a larger scale (along the leaf), the epiphytic populations of the youngest leaves (near the surface) and the eldest ones (close to the sediments) were homogenous, hence suggesting that other factors, independent from the physiology of the plant, may have an impact on epiphytic distribution.     

Recent benthic foraminiferal assemblages from cold-water coral mounds in the Porcupine Seabight

Cold-water coral ecosystems are characterised by a high diversity and population density. Living and dead foraminiferal assemblages from 20 surface sediment samples from Galway and Propeller Mounds were analysed to describe the distribution patterns of benthic foraminifera on coral mounds in relation to different sedimentary facies. Hard substrates were examined to assess the foraminiferal microhabitats and diversities in the coral framework. We recognised 131 different species, of which 27 prefer an attached lifestyle. Epibenthic species are the main constituents of the living and dead foraminiferal assemblages. The frequent species Discanomalina coronata was associated with coral rubble, Cibicides refulgens showed preference to the off-mound sand veneer, and Uvigerina mediterranea displayed abundance maxima in the main depositional area on the southern flank of Galway Mound, and in the muds around Propeller Mound. The distribution of these species is rather governed by their specific ecological demands and microhabitat availability than by the sedimentary facies. Benthic foraminiferal assemblages from coral mounds fit well into basin-wide-scale distribution patterns of species along the western European continental margin. The diversity of the foraminiferal faunas is not higher on the carbonate mounds as in their vicinity. The living assemblages show a broad mid-slope diversity maximum between 500 and 1,300 m water depth, which is the depth interval of coral mound formation at the Celtic and Amorican Margin. The foraminiferal diversity maximum is about 700 m shallower than comparable maxima of nematodes and bivalves. This suggests that different processes are driving the foraminiferal and metazoan diversity patterns.     

Vertical distribution of Hymenophyllaceae species among host tree microhabitats in a temperate rain forest in Southern Chile

Question: Are differences in microhabitat preferences of co‐occurring epiphytic Hymenophyllaceae species (filmy ferns) correlated with differences in ecophysiological responses to light availability and humidity in the host tree? Location: The Andean foothills in south‐central Chile. Methods: We evaluated the distribution pattern of nine filmy fern species in microhabitats that differ in light availability and humidity in four host tree species. A DCA was developed to assess Hymenophyllaceae species microhabitat preference in terms of canopy openness (CO) and relative humidity. We assessed whether differences in chlorophyll content, maximum photochemical efficiency (Fv/Fm), photosynthetic capacity (A_max), evapotranspiration (E) and instantaneous water use efficiency (WUE) are consistent with any pattern. Results: CO and relative humidity differed significantly with height in the host trees. While CO increased with height in a host tree, relative humidity decreased. DCA analysis showed that filmy fern species distribution within and among trees was mainly explained by the relative humidity of the microhabitat. Chlorophyll content, chlorophyll a/b ratio, A_max and E differed significantly among filmy fern species. A_max and E were correlated with axis 1 scores from the DCA analysis. Conclusions: The vertical distribution and abundance of filmy fern species in Chilean temperate rain forest seems to be closely related to the different microhabitats offered by host trees. This pattern may reflect interspecific differences in ecophysiological traits related both to light availability and humidity. Our results suggest that humidity is the main environmental factor driving functional responses and habitat preferences of these filmy fern species.     

Variation in foraging behavior facilitates resource partitioning in a polymorphic cichlid, Herichthys minckleyi

We examined foraging behavior (microhabitat use and feeding behavior) in a trophically polymorphic cichlid fish, Herichthys minckleyi, to address several questions regarding resource partitioning in this threatened species. These include: (1) do morphotypes demonstrate different foraging behaviors? (2) do individuals within a morphotype vary in their foraging behavior (e.g. are some individuals specialists, only using a subset of available resources, while other are generalists)? (3) do foraging behaviors vary between isolated pools? (4) do foraging behaviors vary across seasons? We quantified microhabitat use and feeding behavior for over 100 individuals (of two morphotypes) feeding freely in two isolated pools (populations) and across two seasons (winter and summer). We found differences in foraging behavior between morphotypes and individual specializations within morphotypes; i.e. some individuals specialize on certain food resources by using a few feeding behaviors within a subset of microhabitats, whereas others employ a range feeding behaviors across many microhabitats. Foraging behavior also varied between pools and across seasons. This spatial and temporal variation in foraging behavior and resource use may serve to maintain this polymorphism, as the relative fitness of the each morph may vary over space and time.     

Detection of inconspicuous epiphytic algae supporting food webs in seagrass meadows

Summary Detritus from common seagrasses and other marine angiosperms may often be a less important basis for estuarine food webs than previously believed. In NW Gulf of Mexico seagrass meadows, epiphytic algae have high productivities, palatability, and a more important trophic role than common large plants have. Interdisciplinary field experiments show (1) intensive night-time ingestion of epiphytes by various invertebrate detritivores, (2) very high productivity of epiphytic algae on seagrasses, and (3) assimilation of epiphytes rather than seagrasses, as measured by ¹³C comparisons. These combined data show that many naturally concentrated and potentially competing invertebrates in Gulf of Mexico seagrass meadows feed largely on the algal overgrowth on seagrass blades, even when such algae appear to be sparse. Primary productivity of these epiphytic algae can equal that of the seagrasses, per blade or per unit biomass. Animal ¹³C values tracked epiphytic values rather than seagrass values when comparisons were made over six sites. These measurements reinforce the view that epiphytic algae can be the primary basis of the food web in seagrass meadows.Contribution No. 608 of The University of Texas Marine Science Institute     

Microhabitat Preference of Egernia napoleonis in Undisturbed Jarrah Forest,and Availability and Introduction of Microhabitats to Encourage Colonization of Restored Forest

An animal's microhabitat requirements can impact its ability to colonize restored areas, particularly species requiring slow developing microhabitats, such as logs and woody debris piles. Introduction of these microhabitats may be required to facilitate colonization by some species. Restored bauxite mine‐pits in the Jarrah (Eucalyptus marginata) forest of south‐western Australia contain introduced log piles at densities of 1 ha^?1. However, these have not facilitated colonization by Napoleon's skink (Egernia napoleonis), which rely on logs for habitat and are largely absent from restored sites. We radio‐tracked 12 skinks in unmined forest to determine their microhabitat preferences and examined differences in vegetation structure, and microhabitat and food availability, between restored and unmined forests to identify reasons for their absence. Restored and unmined forests differed in canopy, mid‐ and understory cover and ground substrates, which were all potential barriers to colonization. Food availability was similar between restored and unmined forest, thus not a barrier to colonization. Skinks primarily utilized long logs, large woody debris piles, and large trees; microhabitats that were scarce or absent in restored sites and, therefore, potential barriers to colonization. Using this information, we introduced small woody debris piles into restored sites in close proximity to unmined areas containing skinks to facilitate skink colonization. This showed early signs of success and suggested that the lack of logs and woody debris were barriers to colonization. However, further monitoring is required to accurately determine the long‐term value of woody debris piles in facilitating skink colonization.     

Microhabitat use in a mediterranean riverine fish assemblage

Summary We examined microhabitat use in Barbus graellsii, Barbus haasi, Chondrostoma toxostoma, Rutilus arcasii, and Salmo gairdneri over a 19 month period in the upper Rio Matarraña, Spain. B. graellsii and Ch. toxostoma exhibited non-random microhabitat use during all seasons and preferentially occupied deep microhabitats with heterogeneous substrates. During the majority of seasons in which they were present, B. haasi and R. arcasii occurred in microhabitats similar to those occupied by B. graellsii and Ch. toxostoma. S. gairdneri was over-represented in high velocity microhabitats with erosional substrates. We did not observe any evidence of interspecific interference competition or avoidance. Substrate composition did not appear to affect microhabitat use outside of its covariation with depth and velocity. Seaonal variation in microhabitat use by B. graellsii, B. haasi and Ch. toxostoma was strongly correlated with seasonal changes in microhabitat availability. S. gairdneri, however, occurred closer to the substrate when average velocities were high. Larger B. graellsii and B. haasi sometimes occupied deeper, higher velocity microhabitats than did smaller specimens. Larger B. graellsii also occasionally occurred farther from shelter than did smaller specimens; the reverse was true for B. haasi. Larger Ch. toxostoma sometimes were found farther from both the substrate and shelter than smaller individuals, whereas smaller specimens occasionally inhabited deeper areas with more depositional substrates than did larger Ch. toxostoma. During Late Summer 1985, smaller Ch. toxostoma also occupied microhabitats with higher velocities than did larger specimens. A comparison of microhabitat use for two species present in both upper and lower portions of the Matarraña indicated that most differences in microhabitat use could be attributed to inter-site differences in microhabitat availability. The data suggest, hovever, that both species shifted to more protected microhabitats in the higher velocity site. Assemblage members generally occupied statistically distinguishable microhabitats and could be classified as: 1) high-velocity upper water column (S. gairdneri), 2) low velocity lower water column (B. graellsii, Ch. toxostoma and R. arcasii), and 3) shelter-oriented benthic (B. haasi). The introduction of S. gairdneri during Winter 1984 did not produce microhabitat shifts in any of the native species. Whether or not the native species affected microhabitat use in S. gairdneri is unknown. Interspecific competition for space, however, did not appear to strongly influence microhabitat use among the native species.     

Amphipods on seaweeds: partners or pests?

Summary Herbivorous marine amphipods have been implicated as important grazers on filamentous and ephemeral algae, and thus as beneficial to macrophytes in reducing overgrowth by epiphytic competitors. In North Carolina, USA, amphipods comprise 97% of all macroscopic animals inhabiting the abundant brown seaweed Sargassum filipendula, and peak in abundance between late winter and early summer. I used outdoor tank experiments to test the species-specific impact of common phytal amphipods on the growth of Sargassum and its epiphytes. The results show that seaweed-associated amphipods are a trophically diverse group that could either increase or decrease host fitness depending on their feeding preferences. The amphipods Ampithoe marcuzii, Caprella penantis, and Jassa falcata each significantly reduced growth of epiphytes on Sargassum plants relative to amphipod-free controls, while Ericthonius brasiliensis had no significant effect on Sargassum or its epiphytes. However, amphipod grazing was not necessarily beneficial to Sargassum. A. marcuzii consumed Sargassum in one outdoor tank experiment, reducing its mass by 11%, while Sargassum plants without amphipods grew by 81%. Epiphytes (mostly diatoms and the filamentous brown alga Ectocarpus siliculosus) and detritus remained abundant on these plants suggesting that A. marcuzii preferred the host to its epiphytes. Similarly, when given simultaneous access to Sargassum and to several common foliose and filamentous epiphytes in the lab, A. marcuzii ate Sargassum almost exclusively. The other three amphipods ate no macroalgae. In contrast to A. marcuzii, C. penantis consistently reduced epiphytes with no negative effect on Sargassum. Thus the species composition of the amphipod fauna can determine whether these animals increase or decrease seaweed fitness.     

Microhabitat use by foraging white-clawed crayfish (<Emphasis Type="Italic">Austropotamobius pallipes</Emphasis>) in stream pools in the NE Iberian Peninsula

The white-clawed crayfish (Austropotamobius pallipes) is an endangered species across most of its distribution range, and information on its ecological requirements is needed to implement effective conservation measures. Its habitat use has been studied in different areas and at various spatial scales. However, being a nocturnal species, there is scarce information on its habitat selection during foraging periods. In this work we analyse nocturnal habitat use of white-clawed crayfish in pools of a small stream in the northeastern Iberian Peninsula at two different scales: (1) microhabitat selection and (2) pool characteristics. Large crayfish showed a clear positive selection for deeper microhabitats, a selection pattern that was weaker for medium-sized crayfish and absent for small ones. On the other hand, crayfish of all sizes avoided cobble and boulder microhabitats and positively selected fine substrate and more exposed microhabitats. Crayfish abundance in pools was positively influenced by pool area, pool depth and the availability of fine substrates, especially silt. While studies on white-clawed crayfish habitat use have often stressed the importance of rough substrates as crayfish refuge, our results show that fine substrates are positively selected by foraging crayfish of all size classes and promoted active crayfish abundance in pools. These apparently contradictory results may be due to the differences in microhabitat preferences exhibited by active and inactive crayfish. Thus, our results help to better complete the picture of white-clawed crayfish habitat requirements.     

Diversity of dry forest epiphytes along a gradient of human disturbance in the tropical Andes

Question: Disturbance effects on dry forest epiphytes are poorly known. How are epiphytic assemblages affected by different degrees of human disturbance, and what are the driving forces? Location: An inter‐Andean dry forest landscape at 2300 m elevation in northern Ecuador. Methods: We sampled epiphytic bryophytes and vascular plants on 100 trees of Acacia macracantha in five habitats: closed‐canopy mixed and pure acacia forest (old secondary), forest edge, young semi‐closed secondary woodland, and isolated trees in grassland. Results: Total species richness in forest edge habitats and on isolated trees was significantly lower than in closed forest types. Species density of vascular epiphytes (species per tree) did not differ significantly between habitat types. Species density of bryophytes, in contrast, was significantly lower in edge habitat and on isolated trees than in closed forest. Forest edge showed greater impoverishment than semi‐closed woodland and similar floristic affinity to isolated trees and to closed forest types. Assemblages were significantly nested; habitat types with major disturbance held only subsets of the closed forest assemblages, indicating a gradual reduction in niche availability. Distance to forest had no effect on species density of epiphytes on isolated trees, but species density was closely correlated with crown closure, a measure of canopy integrity. Main conclusions: Microclimatic changes but not dispersal constraints were key determinants of epiphyte assemblages following disturbance. Epiphytic cryptogams are sensitive indicators of microclimate and human disturbance in montane dry forests. The substantial impoverishment of edge habitat underlines the need for fragmentation studies on epiphytes elsewhere in the Tropics.     

Detecting impacts of non‐native species on associated invertebrate assemblages depends on microhabitat

Invasive plants that displace native floral communities can cause changes to associated invertebrate species assemblages. Using a mini‐review of the literature and our own data we add to the still considerable debate about the most effective methods for testing community‐level impacts by invasive species. In endangered saltmarshes of southeast Australia, the non‐native rush Juncus acutus L. is displacing its native congener J. kraussii Hochst., with concurrent changes to floral and faunal assemblages. In two coastal saltmarshes, we tested the hypothesis that the ability to detect differences in the invertebrate assemblage associated with these congeneric rushes depends on the microhabitat of the plant sampled. We used three sampling methods, each targeting specific microhabitats: sweep netting of the plant stems, vacuum sampling of the plant tussock, and vacuum sampling of the ground directly below the plants. Over 3800 individuals and 92 morphospecies were collected across four main taxa: gastropods, crustaceans, hexapods and arachnids. Detection of differences in invertebrate density, richness and composition associated with native compared with non‐native rushes was dependent on the microhabitat sampled and these differences were spatially variable. For example, at one saltmarsh the stems and tussock of J. acutus had a lower density and richness of total invertebrates and hexapods than those of the native J. kraussii. In contrast, crustaceans on the ground were in greater abundance below J. acutus than J. kraussii. This study demonstrates that on occasions where overall differences in the assemblage are not detected between species, differences may become apparent when targeting different microhabitats of the plant. In addition, separately targeting multiple microhabitats likely leads to a greater probability of detecting impacts of invasion. Comparing the invertebrate assemblage without differentiating between or sampling an array of microhabitats can fail to determine the impact of invasive species. These results highlight that a combination of methods targeting different microhabitats is important for detecting differences within the invertebrate community, even for phylogenetically related species.     

Bottom‐up manipulations alter the community structures of galling insects and gall morphs on Neoboutonia macrocalyx trees in a moist tropical rainforest

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Epiphytic ferns and bryophytes of Tasmanian tree‐ferns: A comparison of diversity and composition between two host species

Abstract Ferns, bryophytes and lichens are the most diverse groups of plants in wet forests in south‐eastern Australia. However, management of this diversity is limited by a lack of ecological knowledge of these groups and the difficulty in identifying species for non‐experts. These problems may be alleviated by the identification and characterization of suitable proxies for this diversity. Epiphytic substrates are potential proxies. To evaluate the significance of some epiphytic substrates, fern and bryophyte assemblages on a common tree‐fern species, Dicksonia antarctica (soft tree‐fern), were compared with those on a rare species, Cyathea cunninghamii (slender tree‐fern), in eastern Tasmania, Australia. A total of 97 fern and bryophyte species were recorded on D. antarctica from 120 trunks at 10 sites, and 64 species on C. cunninghamii from 39 trunks at four of these sites. The trunks of C. cunninghamii generally supported fewer species than D. antarctica, but two mosses (particularly Hymenodon pilifer) and one liverwort showed significant associations with this host. Several other bryophytes and epiphytic ferns showed an affinity for the trunks of D. antarctica. Species assemblages differed significantly between both sites and hosts, and the differences between hosts varied significantly among sites. The exceptionally high epiphytic diversity associated with D. antarctica suggests that it plays an important ecological role in Tasmanian forests. Evidently C. cunninghamii also supports a diverse suite of epiphytes, including at least one specialist species.     

Seagrass response to CO2 contingent on epiphytic algae: indirect effects can overwhelm direct effects

Increased availability of dissolved CO₂ in the ocean can enhance the productivity and growth of marine plants such as seagrasses and algae, but realised benefits may be contingent on additional conditions (e.g. light) that modify biotic interactions between these plant groups. The combined effects of future CO₂ and differing light on the growth of seagrass and their algal epiphytes were tested by maintaining juvenile seagrasses Amphibolis antarctica under three different CO₂ concentrations representing ambient, moderate future and high future forecasts (i.e. 390, 650 vs. 900 µl l^?1) and two light levels representing low and high PAR (i.e. 43 vs. 167 µmol m^?2 s^?1). Aboveground and belowground biomass, leaf growth, epiphyte cover, tissue chemistry and photosynthetic parameters of seagrasses were measured. At low light, there was a neutral to positive effect of elevated CO₂ on seagrass biomass and growth; at high light, this effect of CO₂ switched toward negative, as growth and biomass decreased at the highest CO₂ level. These opposing responses to CO₂ appeared to be closely linked to the overgrowth of seagrass by filamentous algal epiphytes when high light and CO₂ were combined. Importantly, all seagrass plants maintained positive leaf growth throughout the experiment, indicating that growth was inhibited by some experimental conditions but not arrested entirely. Therefore, while greater light or elevated CO₂ provided direct physiological benefits for seagrasses, such benefits were likely negated by overgrowth of epiphytic algae when greater light and CO₂ were combined. This result demonstrates how indirect ecological effects from epiphytes can modify independent physiological predictions for seagrass associated with global change.     

Understanding Fossil Phytolith Preservation: The Role of Partial Dissolution in Paleoecology and Archaeology

Opaline phytoliths are important microfossils used for paleoecological and archaeological reconstructions that are primarily based on relative ratios of specific morphotypes. Recent studies have shown that phytolith assemblages are prone to post-depositional alteration involving partial dissolution, however, the manner in which partial dissolution affects morphotype composition is poorly understood. Here we show that morphotype assemblages from four different plant species subjected to controlled partial dissolution are significantly different from the original assemblages, indicating that the stability of various morphotypes differs, mainly depending on their surface area to bulk ratios. This underlying mechanism produces distorted morphotype compositions in partially dissolved phytolith assemblages, bearing vast implications for morphotype-based paleoecological and archaeological interpretation. Together with analyses of phytolith assemblages from a variety of archaeological sites, our results establish criteria by which well-preserved phytolith assemblages can be selected for accurate paleoecological and archaeological reconstructions.     

Arbuscular mycorrhizas and dark septate endophytes in bromeliads from South American arid environment

Most plant roots are associated with glomalean fungi forming arbuscular mycorrhizas (AM) and a wide range are also colonized by ascomycetous dark septate endophytes (DSE). Bromeliaceae species can be epiphytic, rupicolous or terrestrial but their mycorrhizal status is poorly studied. We examined the AM and DSE status of 5 epiphytic and 4 terrestrial Bromeliaceae from an arid area of Central Argentina. The terrestrial species were either dually associated (AM and DSE) or non-associated whereas the epiphytes were only DSE colonized. Terrestrial Bromeliaceae that formed AM-DSE associations were likely responding to the arid conditions of the area and the availability of AM fungal (AMF) spores in the soil. The terrestrialBromelia ubaniana was not colonized either by AMF or DSE. This could reflect its root morphology and high number of root hairs. DSE are endosymbiotic in the stressful ecosystems experienced by canopy epiphytes in the studied environment. The different fungal associations are discussed in relation to the three Bromeliaceae subfamiles and we suggest that environmental features determinethe type of association formed by species in this plant family.     

Seasonal variation in a low shore Fucus serratus (Fucales,Phaeophyta) population and its epiphytic fauna

Seasonal variation in a Fucus serratus assemblage was studied on the Isle of Man, UK over a 13-month period. Algal cover varied greatly, related to shedding reproductive fronds and winter storms. Peak reproduction was recorded in the autumn. There was little change in density of plants, the population was dominated by a bank of germlings (<20 cm) and an adult mode between 50–70 cm. An indistinct third component of recruiting juveniles was present when gaps in the canopy formed. Seasonal variation in the algae was reflected in the population dynamics of the mobile epiphytes such as Littorina mariae and Lacuna pallidula, which exhibited annual life histories. Sessile species (such as bryozoans) utilized the algae year round, dominating the perennial stipes and lower fronds, which were not shed. Other species utilized the algae in a transient fashion: some feeding on the algae (e.g. Idotea), or other epiphytic animals (e.g. Nucella). Fucus serratus, therefore, provides a variety of spatially and temporally variable niches that explain the diversity of epiphytic animal species that exploit this alga.     

The biology of an Antarctic aquatic moss community

SUMMARY. Two species of aquatic moss ( Calliergon sarmentosum and Drepanocladus sp.) occur in deep water in Moss Lake, Signy Island (60° 43'S, 45° 38'W). Their elongate stems support a structurally complex community of epiphytic algae and associated invertebrates which has a greater diversity than the surrounding benthic algal communities.
Qualitative differences in the distribution and abundance of the epiphytic algae are described. Two groups of algae present on both mosses are distinguished–'habitual' and 'casual' epiphytes. On Calliergun , algae are most abundant in the leaf axil. The succession of epiphytes down the stem and the progressive deterioration of the moss plant are used to characterize six stem zones.
The invertebrates are benthic and most move actively among the moss. Six species of rotifers are more or less permanently attached and show a preference for the middle stem zones where epiphyte cover is highest. Four species favour the leaf axil, the other two colonize the bare underside of the leaf.
A settlement experiment has shown the importance of wind-induced mixing in summer for the transport of some epiphytic species from shallow parts of the lake. The settlement of sessile rotifers is effected by their larvae.
Photosynthesis declines from the stem apex to the dead old stem. Much of the primary production of the community is algal. The respiration maximum occurs where the highest concentration of epiphytic algae and invertebrates is found.
Interrelationships between the invertebrates and the epiphytic algae are suggested and a comparison is made between these data and other studies.     

Snail communities increase submerged macrophyte growth by grazing epiphytic algae and phytoplankton in a mesocosm experiment

The relationships between producers (e.g., macrophytes, phytoplankton and epiphytic algae) and snails play an important role in maintaining the function and stability of shallow ecosystems. Complex relationships exist among macrophytes, epiphytic algae, phytoplankton, and snails. We studied the effects of snail communities (consisting of Radix swinhoei, Hippeutis cantori, Bellamya aeruginosa, and Parafossarulus striatulus) on the biomass of phytoplankton and epiphytic algae as well as on the growth of three species of submerged macrophytes (Hydrilla verticillata, Vallisneria natans, and one exotic submerged plant, Elodea nuttallii) in a 90‐day outdoor mesocosm experiment conducted on the shore of subtropical Lake Liangzihu, China. A structural equation model showed that the snail communities affected the submerged macrophytes by grazing phytoplankton and epiphytic algae (reduction in phytoplankton Chl‐a and epiphytic algal abundance), enhancing the biomass of submerged macrophytes. Highly branched macrophytes with high surfaces and morphologies and many microhabitats supported the most snails and epiphytic algae (the biomass of the snail communities and epiphytic algae on H. verticillata was greater than that on V. natans), and snails preferred to feed on native plants. Competition drove the snails to change their grazing preferences to achieve coexistence.