Mayfly Community Research Articles

Seasonal Variability in Community Structure and Habitat Selection of Mayflies (Ephemeroptera) in the Nišava River (Serbia)

ABSTRACTThe sedentary nature of many members of the river macroinvertebrate community allows spatial and temporal analyses of disturbance effects. This characteristic also implicates their strong affinity towards certain types of microhabitats. The results of the mayfly (Ephemeroptera) community structure analysis in the Nisava River (Serbia) have shown a clear dependence of the mayfly community on habitat type (solid vs. loose bottoms), physical and chemical parameters (nutrient content), and season. Over a one-year period, on a monthly basis, 28 species of mayfly were identified at 12 localities along the 151 km long stretch of the Nišava River. The community structure changed longitudinally with the changes of physical and chemical parameters and habitat type. The lowest Shannon's diversity index was estimated for the localities with the lowest percentage of solid bottoms (rock, pebble). The highest diversity index was estimated for localities with the highest percentage of solid bottoms and the lowest average content of phosphorus and nitrogen.

Mayfly communities in two Neotropical lowland forests

In 2006, the Stroud Water Research Center conducted inventories of stream macroinvertebrates in the Peninsula de Osa in Costa Rica and the Madre de Dios watershed in eastern Peru. Both areas have extensive lowland tropical rainforests under threat from road development, tourism, poaching and gold mining. The mayfly communities of the two regions were substantially different in family relative abundances. In Osa the mayfly community was more or less evenly divided among Baetidae, Leptohyphidae, and Leptophlebiidae. In streams where one group was clearly dominant, this was most often Leptohyphidae. By contrast, in the Madre de Dios watershed Leptophlebiidae was often 75% or more of the mayfly fauna while Leptohyphidae was 20% or less. In both Osa and Madre de Dios, EPT indices were calculated for impacted streams and relatively undisturbed streams. However, physical characteristics such as stream size and substrate diversity were often a better predictor of community composition than human activity.

Community structure and distribution of Ephemeroptera and Plecoptera larvae in lowland karst rivers in Slovenia

Mayfly and stonefly larval community compositions were investigated in lowland karst rivers. From January to December 2005, 49 benthos samples were taken using a multi-habitat approach. Environmental variables were measured in about monthly intervals. Altogether, 26 mayfly taxa (20 species) and 17 stonefly taxa (13 species) were recorded. Eight species were common, whereas 16 taxa were rare. Only Baetis rhodani and Ephemerella ignita occurred frequently at all sites. Significant differences were observed among sampling sites in diversity and richness metrics but neither in abundance nor in values of index of biocenotic regions. Spatial and seasonal differences amongst assemblages were determined by NMS. The relationship between mayfly and stonefly assemblage structure and seasonally varied environmental factors were investigated using canonical correspondence analysis (CCA). Mayfly and stonefly larval taxa distribution was best correlated to an eutrophication gradient represented by conductivity, nitrate concentration and dissolved oxygen concentration.

Structure and spatial variability of mayfly (Ephemeroptera) communities in the upper Hron River basin

Mayflies were sampled from eleven sites in six tributaries of the upper Hron River. Mayfly communities were ordinated and related to environmental factors using multiple regression and principal component analysis. Communities of headwater sites were dominated by Rhithrogena iridina which was gradually replaced by Baetis alpinus, at the lower reaches. Total mayfly species richness was inversely related to stream slope and overall abundance was inversely related to altitude. The prominent factor influencing mayfly communities was a complex longitudinal gradient as proposed by the river continuum concept. There were no significant differences in community composition and structure between the left-and right-hand tributaries of the Hron River.

Mayflies (Insecta: Ephemeroptera) and the assessment of ecological integrity : a methodological approach

Mayflies (Ephemeroptera) play an important role in almost all undisturbed freshwater communities and their larvae frequently form a considerable part of the material sampled during biomonitoring procedures. Mayfly taxa are widely accepted as bioindicators for water quality and form an integral part of standardized systems for the saprobic evaluation of running waters. Nevertheless, successful interpretation of data depends heavily on sampling strategies and the technical concepts adopted therein. The following paper discusses current problems affecting the correct assessment of mayfly community structure and proposes basic requirements to improve the meaningfulness of limnological routine sampling with regard to Ephemeroptera. The topics covered include: mayfly diversity in different types of freshwater communities in Europe; natural habitats and sampling sites / sampling strategies; life cycles and minimum sampling frequency; level of identification and interpretation of data.

Life Histories and Abundance Patterns of Snag-Dwelling Mayflies in a Blackwater Coastal Plain River

A diverse mayfly community (28 species) was found in the Ogeechee River, a blackwater river in the Georgia Coastal Plain. Quantitative samples of snag habitat, where most species (22) were found, were collected at 2-4 wk intervals in 1982 to investigate life history characteristics, and at monthly intervals in 1983 to determine consistency of seasonal and annual abundance patterns. Baetidae and Heptageniidae were abundant throughout each year with average densities of 1553-5981 / m² (1982-1983) and 1498-1828 / m² of snag surface, respectively. Field data for the most common species of Baetidae (Baetis ephippiatus, B. intercalaris) and Heptageniidae (Stenonema exiguum, S. integrum, S. modestum) showed no recognizable pattern of cohort development. This developmental asynchrony and long emergence periods for S. exiguum and S. modestum are consistent with previously published growth studies indicating multivoltinism. Ephemerellidae (551-719/m²), Oligoneuriidae (206-469/m²), Tricorythidae (721-1599/m²) and Caenidae (114-110/m²) were also commonly found on snags, but were seasonal in abundance. The major species of Ephemerellidae (Ephemerella argo, E. dorothea, Eurylophella sp.) showed distinct single cohorts developing primarily during winter/spring. Isonychia spp. (Oligoneuriidae) also showed a well-defined winter cohort, but had as many as two weakly defined cohorts during warm months. Caenis spp. (Caenidae) and Tricorythodes sp. (Tricorythidae) occurred primarily in summer months, during which time they were able to pass through multiple generations, as substantiated by either long emergence periods or independent growth studies. Major differences in life histories occurred between rather than within families. Relative abundance and seasonality at the family level were very consistent between years. The high degree of life history overlap in this diverse mayfly assemblage raises questions about the relationship between phenology and community structure, as well as latitudinal patterns of species richness.

A review of the effect of river regulation on mayflies (Ephemeroptera)

AbstractImpoundment and diversion of watercourses for power production and water supply can have profound effects on the mayfly fauna. To explain such effects a species‐specific approach is adopted on account of differing habitat requirements and life histories in the order and even within genera. Environmental conditions such as discharge and flow patterns, temperature, food availability, and predation may be changed. This leads to changes in the density and species composition of the mayfly community, especially when there is a hypolimnion drain from reservoirs. Temperature changes below such reservoirs may remove obligatory life cycle thresholds. Prolonged periods of low discharge lead to the dominance of genera, such as Paraleptophlebia, Choroterpes, Siphlonurus, and Pseudocloen, typical of slow‐flowing and lentic habitats.The life cycle plasticity and opportunism shown by Baetis rhodani in Europe and B. tricaudatus in North America have undoubtedly contributed to their success in regulated rivers. The life history characteristics of Tricorythodes are also advantageous below dams. The increased growth of periphyton and mosses below many dams favour certain Ephemerellidae, but restrict or eliminate many Heptageniidae. In order to survive adverse conditions, flexible life cycles or a short period of rapid nymphal growth coupled with a long period of egg development, are advantageous.

Structure, zonation, and species diversity of the mayfly communities of the Bel� River basin, Slovakia

Four mayfly taxocoena which correspond to zones in the river continuum concept of Vannote et al. (1980) and to the zonation concept of Illies & Botosaneanu (1963), were distinguished by cluster analysis in the Bela River basin, Slovakia. By principal components analysis, taxocoena were shown to be separated along a complex gradient dominated by altitude and slope. An increase of species diversity was observed downstreams. The species-diversity data can be fitted to a geometric series, and interpreted by the niche preemption hypothesis. Equitability and the ratio of Baetidae to Heptagenidae are supposed to indicate ecological conditions.

The Replacement ofStenonemaspp. byCaenis diminutaWalker as the Numerical Dominant in the Mayfly Assemblage of a Thermally-Stressed Stream

ABSTRACT Mayfly community structures in a thermally-stressed, previously thermally-stressed and an undisturbed stream were compared based on nymphal colonization of leaf packs incubated over a 48 d period from December 1982 to February 1983. Temperatures ranged from 7–31C in the thermally-stressed stream and from 4–12C in the other two streams. Accumulated degree days (>0C) were 734, 340 and 322 for the thermally-stressed, post-stressed and undisturbed streams, respectively. Stenonema spp. numerically dominated the mayfly fauna over the sampling period in the undisturbed (70%) and post-stressed (98%) streams, but was replaced by Caenis diminuta Walker (88%) in the stream receiving thermal effluent from a nuclear production reactor. Caenis diminuta is tolerant of rapidly fluctuating (Delta;T > 11C/hr) and high temperatures (possibly up to 40C).

Mayfly communities in a Laurentian watershed (Insecta; Ephemeroptera)

Mayfly communities were investigated in a series of four lakes, two beaver ponds, and 13 streams in a Laurentian watershed. Forty-five taxa were collected mostly through emergence trapping of adults (76 trap-years). Q and R analyses were used to show similarities between the stations and associations between the species. The middle reaches of the mainstream harbour the richest communities which are an assemblage of a few ubiquitous species (Baetis gr. pygmaeus, Stenonema modestum, Habrophlebia vibrans, and Paraleptophlebia volitans), lotic species (Baetis flavistriga, B. pluto, Stenonema vicarium, and Heptagenia pulla) some of which show a restricted distribution (Paraleptophlebia adoptiva, P. Ontario, Leucrocuta hebe, and Stenacron interpunctatum heterotarsale), and also lentic species (Eurylophella verisimilis, Leptophlebia cupida, Cloeon simplex, C. rubropictum, Centroptilum album, and Stenacron interpunctatum frontale). The headwater streams contain no distinct element, except perhaps Siphlonurus typicus, but rather the more resistant or dispersive species from the mainstream, mainly Ephemerellidae and Leptophlebiidae. The lower reaches of the mainstream are characterized by the addition of a few typical river species, Serratella sordida and Epeorus vitreus. Lacustrine communities are less diverse, comprising mostly the lentic species from the streams plus a distinctive element (Stenacron interpunctatum canadense, Callibaetis ferrugineus, and Hexagenia limbata occulta). Only Leptophlebia cupida colonizes the bog lake, and no species occur in the beaver ponds. Most congeneric species are either spatially or temporally segregated. The sections of the mainstream produce an average of some 1000 adult mayflies/m2 per year; other streams are less productive and the lakes even less so (less than 100/m2). The seasonal succession of the species and the emergence patterns of the dominant species are illustrated; a classification of emergence patterns is attempted on the basis of the present data and of other recent studies.