Mayfly Nymphs Research Articles

Distinguishing among declarative, descriptive and causal questions to guide field investigations and student assessment

Teachers as well as students often have difficulty formulating good research questions because not all questions lend themselves to scientific investigation. The following is a guide for high-school and college life-science teachers to help students define question types central to biological field studies. The mayfly nymph was selected as the example study organism because they are common in warm humid climates worldwide and are used as key indicators of water quality and stream health. Assessment of students’ work should be a logical extension field investigations. Assessment simply using traditional multiple-choice items after research investigations communicates to students that recall of specific facts (declarative knowledge) is important and investigative processes (procedural knowledge) are not important. Assessment of declarative knowledge should not be ignored, but procedural knowledge should be included. Both are important to science literacy.

Ephemeroptera (Insecta) ocorrentes no leste do Estado do Mato Grosso, Brasil

Com o objetivo de apresentar um levantamento da fauna de Ephemeroptera no Estado do Mato Grosso, investigamos as ninfas de Ephemeroptera, principalmente de duas bacias hidrográficas do leste do estado. Sessenta e sete espécies/morfoespécies em 41 gêneros e oito famílias foram encontradas. Quatro espécies (Cloeodes redactus Waltz & McCafferty, 1987 e Waltzoyphius roberti Thomas & Peru, 2002 [Baetidae], Tricorytopsis chiriguano Molineri, 2001 [Leptohyphidae] e Microphlebia surinamensis Savage & Peters, 1983 [Leptophlebiidae]) foram registradas pela primeira vez no Brasil. As famílias Euthyplociidae, Polymitarcyidae e Coryphoridae foram registradas pela primeira vez para o Mato Grosso, assim como 19 gêneros e 18 espécies. Vinte e cinco espécies não foram identificadas devido à falta de informação envolvendo o estágio ninfal de seus respectivos gêneros. Assim como demonstrado em outros trabalhos com o grupo, a ordem se mostrou mais diversa do que se conhece atualmente, especialmente se considerarmos as várias fisionomias e bacias hidrográficas do estado que se mantêm desconhecidas.

Accumulation and Depuration of Polychlorinated Biphenyls from Field-Collected Sediment in Three Freshwater Organisms

As laboratory-based bioaccumulation methods are standardized and expanded to include other test species, kinetic studies assessing the major classes of contaminants with these species are needed to adequately select the standard duration for bioaccumulation tests. In the present study we measured the uptake (28-d exposure) of polychlorinated biphenyls (PCBs; total and selected congeners) from field-contaminated sediment in the oligochaete Lumbriculus variegatus, mayfly nymph Hexagenia spp., and fathead minnow Pimephales promelas. Depuration (25 d) of PCBs was measured in organisms that had been transferred to clean sediment after the 28-d exposure. Uptake and elimination of PCBs was rapid in L. variegatus and Hexagenia spp. Tissue residues reached steady-state concentrations within 28 d; elimination rates and biota-sediment accumulation factors (BSAFs) of the PCB congeners were not correlated with K(OW). Uptake and elimination rates of PCBs were slower in P. promelas, and it is not clear whether steady-state was reached in fish tissues. Elimination rates of the PCB congeners significantly decreased with increasing K(OW) in fish. The appropriateness of a 28-d exposure for measuring steady-state concentrations in tissue of the invertebrates was confirmed, but further study is required for fish.

New mayfly nymphs (Insecta: Ephemeroptera) from Yixian Formation, China

Three new species of mayfly nymphs, Clavineta excavata sp. nov., Clavineta brevinodia sp. nov., and Siberiogenites branchicillus sp. nov., from the Yixian Formation (Late Jurassic-Early Cretaceous) in western Liaoning Province, China, are described. These mature nymphs are small-sized, with the body less than 16.0 mm long. The systematic position of the genera Clavineta and Siberiogenites, which are recorded for the first time in the Yixian Formation, is briefly discussed.

A comparison of the bioaccumulation potential of three freshwater organisms exposed to sediment‐associated contaminants under laboratory conditions

In the field of sediment quality assessment, increased support has been expressed for using multiple species that represent different taxa, trophic levels, and potential routes of exposure. However, few studies have compared the bioaccumulation potential of various test species over a range of sediment contaminants (hydrophobic organics and metals). As part of the development and standardization of a laboratory bioaccumulation method for the Ontario Ministry of the Environment, the oligochaete Lumbriculus variegatus, mayfly nymph Hexagenia spp., and juvenile fathead minnow Pimephales promelas were exposed to a variety of field-contaminated sediments (n = 10) to evaluate their relative effectiveness for accumulating different contaminants (e.g., dichlorodiphenyltrichloroethane [DDT] and metabolites, polychlorinated biphenyls [PCBs), polycyclic aromatic hydrocarbons [PAHs), polychlorinated dibenzo-p-dioxins and dibenzofurans [PCDD/Fs), and heavy metals). Bioaccumulation was usually highest in L. variegatus but also most variable within and (relative measures) between sediments. Bioaccumulation was similar between L. variegatus and Hexagenia spp. in most of the sediments tested. Significant differences in bioaccumulation between species were observed for DDT, dichlorodiphenyldichloroethane (DDD), PAHs, and PCDD/Fs. The present study indicates that species-specific differences in bioaccumulation may, but do not always, exist and can vary with contaminant and sediment type. The choice of test species or combination to use in a standard test method may depend on the objectives of the sediment quality assessment and data requirements of an ecological risk assessment. The results of the present study provide insight for selection of test species and validation of laboratory methods for assessing bioaccumulation with these species, as well as valuable information for interpreting results of bioaccumulation tests.

Heavy metals in sediments and uptake by burrowing mayflies in western Lake Erie basin

During the past two decades, burrowing Hexagenia mayflies have returned to the western basin of Lake Erie. Because of their importance as a prey resource for higher trophic levels and their extensive residence time in potentially contaminated sediment, Hexagenia may be a source of heavy metal transfer. To better understand the distribution and transfer of heavy metals in sediment and mayflies, sediment and mayfly nymphs were collected from 24 locations across the western basin of Lake Erie in May 2007. Following USEPA protocols, samples were analyzed for 16 elements using ICP-OES or ICP-MS. Metal concentrations in the sediments exceeded the Threshold Effect Level for at least one metal at all sample sites. Sediment heavy metal distribution profiles indicate metal concentrations are correlated with organic matter content, and the highest heavy metal concentrations were found in the central deeper region of the western basin where organic content in the sediments was greatest. Hexagenia were distributed throughout the western basin, with greatest density (1350/m 2) within the Detroit River plume. The Cd and Zn levels in mayflies were on average approximately 4 and 2 times greater, respectively, than sediment levels, and the Cd concentrations in the sediments exceeded the Threshold Effect Level at 27 of 28 sites and exceeded the Probable Effect Level at 9 of 28 sites. Spatial representation of heavy metal concentrations in mayflies exhibited a similar pattern to the spatial distribution of heavy metals and organic matter in the sediments with higher concentrations of metals found in mayflies residing in the central deeper region of the western basin.

New species and new stage descriptions of Campsurus major species group (Polymitarcyidae: Campsurinae), with first report of silk-case construction in mayfly nymphs

Campsurus major, C. argentinus and C. amapaensis sp. nov. form a monophyletic group supported by the following apomorphies in the male genitalia: robust pedestals with a widely rounded inner-posterior margin and a more acute and thinner outer margin, penes strongly sclerotised and curved ventrally, each lobe twisted outwards, and with a small membranous lobe on ventral margin. The nymphs of Campsurus major and C. argentinus and the female adult of C. major are described for the first time and illustrated here; the male adults of both species are redescribed. A new species, C. amapaensis, is described from male imagos. The following new synonymies are proposed: Campsurus argentinus Esben-Petersen (= C. pallidus Needham & Murphy, junior synonym) and C. major Needham & Murphy (= C. brasiliensis Traver, junior synonym). The nymphs of both species are reported to use silk to build soft cases and to glue substrate particles. A list of characters useful to distinguish the treated species from others in the genus is given.

Attributes of the wood-boring trace fossil Asthenopodichnium in the Late Cretaceous Wahweap Formation, Utah, USA

A common, macroscopic, wood-boring trace fossil occurs in the Upper Cretaceous braided- and meandering-stream deposits of the upper and capping sandstone members of the Wahweap Formation in Grand Staircase-Escalante National Monument, Utah. Upon detailed examination, this trace warrants assignment to Asthenopodichnium (Thenius, 1979). Asthenopodichnium is a scoop-shaped, pouch-like trace that is preserved as iron hydroxide rind casts of wood fragments and logs. The long axes of the scoops are typically aligned parallel or sub-parallel to the long axis of the preserved wood. In the upper and capping sandstone members, Asthenopodichnium characteristically occur in dense clusters in which pouches overlie one another, although they are found as isolated, individual traces and tight clusters of multiple individuals as well. The Asthenopodichnium trace maker has been purported to be the possible product of mayfly nymphs developed in moving fresh water. As a fresh water trace Asthenopodichnium may be used in conjunction with Teredolites, a marine or brackish indicator, to delimit the brackish-fresh water limit in estuarine deposits.

The Effect of Organism Density on Bioaccumulation of Contaminants from Sediment in Three Aquatic Test Species: A Case for Standardizing to Sediment Organic Carbon

Laboratory methods for measuring bioaccumulation of organic contaminants from sediment into aquatic organisms continue to improve, but some aspects are still in need of standardization. From a review of published methods, we noted that the loading density of organisms was determined inconsistently and was primarily based on either sediment volume or total organic carbon (TOC). The rationale mainly expressed for standardizing to TOC was to minimize the depletion of sediment contaminants. However, even when density was standardized to TOC, the relative amount of TOC provided (i.e., ratio of TOC to organism dry weight [dw]) was highly variable. In this study, we examined the effect of organism density (standardized to sediment TOC or volume) on bioaccumulation in three freshwater organisms. The oligochaete Lumbriculus variegatus, mayfly nymph Hexagenia spp., and fathead minnow Pimephales promelas were exposed for 28days to two field-contaminated sediments that varied in concentration of PCBs and TOC. Densities tested were 50:1 and 27:1 ratios of TOC to organism dw and 140ml sediment/g wet weight (ww) biomass, yielding low to high organism densities. Bioaccumulation in Hexagenia spp. was significantly higher at the lowest organism density compared with the highest organism density when exposed to site 2 sediment (1.1% TOC) but only with tissue concentrations expressed on a ww basis. Otherwise, there was no significant effect of density on bioaccumulation in organisms exposed to sediments from site 1 (12% TOC) or site 2. Survival of Hexagenia spp. was adversely affected at the highest organism density when the relative amount of TOC was low. The results of this study support the recommendation of standardizing organism density relative to a particular amount of TOC for invertebrate species. A 27:1 ratio of TOC:organism dw was selected as a standard organism density for a new bioaccumulation method because survival, growth, and bioaccumulation were not impacted relative to a 50:1 ratio, and less sediment was required. This density is recommended as an appropriate ratio for sediment bioaccumulation assessments in general.

On the effect of kraft pulp mill wastes on the water flea and the may-fly nymph

On the effect of kraft pulp mill wastes on the water flea and the may-fly nymph

A preliminary study into the potential of mayflies (Ephemeroptera: Baetidae and Caenidae) as bio-indicators of stream health in Fiji

flowing through an area of tropical lowland rainfor est and urban streams running through residential and indus trial areas. The two rural streams were Waisila Stream l ocated within the Colo-I-Suva Forest Reserve approximately 6 km from Suva and the Savura water catchment within the forested area of the upper Wailoku River. The two urban streams were the Nabua stream where it runs through an army barracks and the Nabukalou creek running directly through Suva city centre. Mayfly nymphs were sampled from riffles in each stream by lifting ten rocks and vigorously brushing the surface of each with a soft brush while a fine-mesh net was held down stream. All mayfly nymph specimens were preserved in 80% ethanol until being examined under a dissecting microscope and identified to family leve l according to Dean and Suter (1996). Five samples of nymphs were collected from five replicate sites in each stream (approximately 10m of stream length) on each stream. The samples collected within each site wer e then pooled.

Mayfly (Insecta: Ephemeroptera) community structure as an indicator of the ecological status of a stream in the Niger Delta area of Nigeria

Ephemeroptera is an important group of insects used in the bioassessment and monitoring of freshwater bodies worldwide because of their relative abundance in a wide variety of substrates and their increasing chances of detecting pollution impacts. In this study, their faunistic composition and spatiotemporal variations in density and diversity in River Orogodo (Southern Nigeria) was investigated at five ecologically distinct stations over a 12-month period. The mayfly nymph community responses to environmental variables were evaluated by means of biological measures and multivariate analysis (redundancy analysis [RDA]). Thirteen morphologically distinct taxa belonging to six families were identified. The dominant taxa were Afrobaetodes pusillus (23.1%), Baetis sp. (13.7%), and Caenis cibaria (11.4%). The density of Ephemeroptera differed significantly (p < 0.05) both in space and time. Diversity was influenced by substrate heterogeneity which in turn was influenced by catchment processes such as flooding and anthropogenic activities especially abattoir effluent. Based on the RDA ordination and relative abundance data, Baetis sp. dominated at impacted stations while a more equitable distribution of species were observed in less disturbed sites. Water velocity, canopy cover, nature of bottom sediments, and the amount of dissolved oxygen also accounted for the variations in Ephemeroptera densities at the different stations. Shannon diversity, taxa richness, and evenness were lowest in station 3 (the abattoir discharge site).

Trichomycetes from lentic and lotic aquatic habitats in Ontario, Canada

Fungi and protists make up an ecological group, trichomycetes, that inhabit the guts of invertebrates, mostly aquatic insects. Trichomycetes are reported herein from arthropods collected in lotic habitats (fast flowing streams) and lentic environments (ponds, ditches, seeps, and lakes) from 11 sites in Algonquin Park and 6 other sites in Ontario, Canada. Thirty-two trichomycete species were recovered, including 7 new species: Legeriomyces algonquinensis , Legeriosimilis leptocerci , Legeriosimilis whitneyi , and Paramoebidium umbonatum are described from mayfly nymphs (Ephemeroptera); Pennella digitata and Glotzia incilis from black fly and midge larvae (Diptera), respectively; and Arundinula opeongoensis from a crayfish (Crustacea). Legeriomyces rarus Lichtw. &amp; M.C. Williams and Stachylina penetralis Lichtw. are new North American records, and seven species are documented for the first time in Canada. More common and widely distributed trichomycete species such as Harpella melusinae Léger &amp; Duboscq and Smittium culicis Manier, were also recovered. Most previous studies on trichomycetes have been done primarily in lotic environments but clearly lentic systems (e.g., ponds and lakes) harbour diverse arthropod communities and further exploration of these habitats will continue to increase our knowledge of trichomycete diversity.

Aquatic hemiptera of Pocharam lake, Andhra Pradesh

Systematic Account Family: Nepidae Subfamily: Ranantrinae 1. Ranatra elongata (Fabricius) 1790. Ranatra elongata Fabricius, Skirf. Nat.Selesk., 1: 228 1994. Ranatra elongata Fabricius: Thirumalai, Rec. zool. Surv. India, Occ. Pap. No. 165: 22 Material examined: 3 exs., 4.xi.2003, Wadalaparthy, S.S. Kamble & Party; 4 exs., 22.xii.2004, Rajpet, Deepa & Party; 4 exs., 12.iv.2005, Pocharam village, SVAC Sekhar & Party. Diagnostic characters: This species can be identified by the structure of the anterior femur, which is provided with a triangular tooth beyond the middle of its length, and the metasternal process, which is subtriangular. Remarks: It feeds on tadpoles, nymphs of mayflies and other aquatic hemipterans. During dry seasons it is known to migrate in search of suitable areas. Distribution: India: Andhra Pradesh, Bihar, Delhi, Jammu & Kashmir, Karnataka, Kerala, Madhya Pradesh, Maharashtra, Orissa, Pondicherry, Rajasthan, Tamil Nadu, Uttar Pradesh, West Bengal. Elsewhere: Australia, Nepal, Sri Lanka.

Acute Toxicity of Aqueous Copper, Cadmium, and Zinc to the Mayfly Rhithrogena hageni

Heptageniid mayfly nymphs have been suggested as sensitive indicators of metal contamination in streams based on biomonitoring studies, experimentation in situ, and experimentation in microcosm. Laboratory tests were conducted to evaluate the sensitivity of Rhithrogena hageni, a heptageniid mayfly, to waterborne copper, cadmium, and zinc. Tests were conducted with soft water (hardness = 40-50 mg/L) at about 12 degrees C. Toxicity endpoints were survival and moulting (%/day). Median 96 hr lethal concentrations were 0.137, 10.5, and 50.5 mg/L for copper, cadmium and zinc, respectively. The average daily moulting rate of survivors significantly decreased after exposure to these metals in solution.

First experimental observations on the development of Rhabdochona denudata (Nematoda: Rhabdochonidae) in the intermediate host

Two species of mayfly nymphs, Habroleptoides modesta (Hagen) and Habrophlebia lauta (Eaton) (Ephemeroptera: Leptophlebiidae), were found as suitable experimental intermediate hosts of the fish nematode Rhabdochona denudata (Dujardin, 1845) (Rhabdochonidae), an intestinal parasite of Palaearctic cyprinids. The parasite's eggs were obtained from nematode gravid females parasitizing the European chub, Leuciscus cephalus (L.), of the Rokytná River, Czech Republic. At the water temperature of 9 degrees C, the eggs of R. denudata were ingested by the intermediate host and the hatched, toothed (with a minute cephalic boring tooth) first-stage larvae about 200 microm long penetrated into the body cavity of the mayfly. There the larvae grew and moulted twice (on 16-18 and 30-35 days p.i.) before attaining the third stage, which is already infective for the fish definitive host. Infective larvae of this stage were about 1.5 mm long and their morphology resembled that of adults except for the vestibule structure; they became encapsulated as in those of other congeneric species.

Food Habits of Four Bottom‐Dwelling Gobiid Species at the Confluence of the Danube and Hron Rivers (South Slovakia)

AbstractSince 1997, three newNeogobiusspecies (Neogobius kessleri,N. fluviatilisandN. melanostomus) have been regularly recorded in the Slovak part of the Danube River, formerly inhabited only by one native gobiid species (Proterorhinus marmoratus). The study of their food habits proved that the amphipodCorophium curvispinum,chironomid larvae and pupae, caddis fly larvae (Hydropsychesp.) and mayfly nymphs (Ephoron virgo,Potamanthus luteus) were the most important food items contributing to the similarity of the diets of the gobiid species. Fish (0+Zingel zingelandSander lucioperca) appeared in the diet ofN. kesslerionly. (© 2007 WILEY‐VCH Verlag GmbH &amp; Co. KGaA, Weinheim)

Landscape variation in C sources of scraping primary consumers in streams

AbstractWe studied variation in C and energy flow in stream food webs by examining primary consumer diets and potential food sources at 8 sites of different drainage areas in the South Fork Eel River drainage. Both heptageniid mayfly nymphs and Glossosoma caddisfly larvae are considered scrapers in traditional functional feeding group classification, but past studies suggested that they differed in their relative use of terrestrial and algal C in some streams. In our study, microscopic examination and stable C isotope ratios (δ13C) suggested an increasing contribution of algae to both epilithic biofilms and fine particulate organic matter as stream drainage area and productivity increased. The proportion of algal cells in biofilms of small, unproductive streams was low, and biofilm δ13C values were similar to those of terrestrial detritus, suggesting that biofilms were composed primarily of heterotrophic microorganisms. Glossosoma larvae fed selectively on algae where it was scarce within the biofilms of ...

New mayfly nymphs from the Jurassic of Northern and Northeastern China (Insecta: Ephemeroptera)

Four new species of mayfly nymphs, Furvoneta relicta sp. nov., Clavineta eximia sp. nov. (originally Mesoneta antiqua), Mesobaetis latifilamentacea sp. nov., and Stackelbergisca cylindrata sp. nov. are described from the Jurassic of China. All these species may have inhabited lakes rather than flowing water. The geological age and stratigraphical correlation of the nymph-bearing strata are briefly reviewed.

Clouds, shadows or twilight? Mayfly nymphs recognise the difference

Summary1. We examined the relative changes in light intensity that initiate night‐time locomotor activity changes in nymphs of the mayfly, Stenonema modestum (Heptageniidae). Tests were carried out in a laboratory stream to examine the hypothesis that nymphs increase their locomotion in response to the large and sustained reductions in relative light intensity that take place during twilight but not to short‐term daytime light fluctuations or a minimum light intensity threshold. Ambient light intensity was reduced over a range of values representative of evening twilight. Light was reduced over the same range of intensities either continuously or in discrete intervals while at the same time nymph activity on unglazed tile substrata was video recorded.2. Nymphs increased their locomotor activity during darkness in response to large, sustained relative light decreases, but not in response to short‐term, interrupted periods of light decrease. Nymphs did not recognise darkness unless an adequate light stimulus, such as large and sustained relative decrease in light intensity, had taken place.3. We show that nymphs perceive light change over time and respond only after a lengthy period of accumulation of light stimulus. The response is much lengthier than reported for other aquatic organisms and is highly adaptive to heterogeneous stream environments.