Rocky Streams Research Articles

Diet of two syntopic species of Crenuchidae (Ostariophysi: Characiformes) in an Amazonian rocky stream

Abstract This study assessed the diet of two poorly known syntopic fish species of the family Crenuchidae, Characidium aff. declivirostre and Leptocharacidium omospilus, in a Presidente Figueiredo´ rocky stream, Amazonas, Brazil. The stomach contents were analyzed and their Frequency of Occurrence (FO %) and Relative Volume (Vol %) were combined in a Feeding Index (IAi). We examined 20 individuals of C. aff. declivirostre and 23 of L. omospilus. The Morisita-Horn Index was used to estimate the overlap between the diets of these species. Immature insects were the most valuable items consumed by both fish species. The diet of C. aff. declivirostre was mainly composed of larvae and pupae of Chironomidae, while L. omospilus predominantly consumed larvae of Hydroptilidae, Hydropyschidae and Pyralidae. Thus, both species were classified as autochthonous insectivorous. Characidium aff. declivirostre was considered a more specialized species, probably reflecting lower feeding plasticity or the use of more restricted microhabitats compared to L. omospilus. When the food items were analyzed at the family taxonomic level, the diet overlap between these species was considered moderate (Morisita-Horn Index = 0.4). However, a more thorough analysis, at the genus level, indicates a very low diet overlap. Therefore, we conclude that the feeding segregation between C. aff. declivirostre and L. omospilus may favor their co-existence, despite their high phylogenetic closeness.

Development of Nine Microsatellite Markers forParamesotriton hongkongensis(Hong Kong Newt) Through Shotgun Sequencing and Cross-species Amplification in Other Asian Salamandrids

The Hong Kong newt (Paramesotriton hongkongensis) is a tropical stream-dwelling salamandrid native to Hong Kong and coastal areas of Guangdong Province, China, inhabiting small rocky hill streams and surrounding forests. It is categorized as “near threatened” on the IUCN Red List because of range-wide habitat degradation and vulnerability to over-exploitation for the pet trade. Nine novel polymorphic microsatellite markers were developed and characterized using Illumina paired-end shotgun sequencing. Number of alleles per locus ranged from 10 to 19 (median=14). Cross-species amplification was attempted in four species of Asian newt: Cynops ensicauda, Pachytriton granolosus, Paramesotriton chinensis, and Tylototriton shanjing, which included two species of conservation concern, with varying degrees of success. The nine novel markers can be used to quantify genetic variability among isolated populations and have potential forensic applications in a number of Asian newt species that are highly threatened by over-exploitation throughout their ranges.

Revision of the Australian species of Hydropeza Sinclair (Diptera: Empididae: Ragadinae subfam. nov.)

Nine new species of Hydropeza Sinclair from Australia are described (H. angulata sp. nov. (N. Queensland), H. aptera sp. nov. (Tasmania), H. cornuta sp. nov. (Queensland), H. curvata sp. nov. (N. Queensland), H. divaricata sp. nov. (N. Queensland), H. intricata sp. nov. (N. Queensland), H. queenslandensis sp. nov. (N. Queensland), H. tasmanica sp. nov. (Tasmania), H. unguicula sp. nov. (Tasmania)). In Australia, Hydropeza is currently widely disjunct in distribution, known only from Tasmania and northern Queensland (Wet Tropics), absent from intervening regions despite extensive surveys of rocky streams and creeks. The male terminalia are illustrated, distributions mapped and a key to species is presented. The subfamily Ragadinae subfam. nov. is proposed for the Ragas-group of genera (Dipsomyia Bezzi, Hormopeza Zetterstedt, Hydropeza, Ragas Walker, Zanclotus Wilder). A revised phylogeny of the species of Hydropeza, including species from New Zealand and Chile, is presented and discussed.

Use of self-organizing maps in modelling the distribution patterns of gammarids (Crustacea: Amphipoda)

Self-organizing maps (SOMs) are increasingly popular methods for processing high-dimensional ecological data; however, their potentials are not yet fully utilized. It was our objective to prove evidence on an unknown advantage of SOMs, which we aimed to test using data on the spatial distributional patterns of gammarids. Quantitative samples and a wide spectrum of environmental data were obtained from the catchment area of two of the largest side tributaries of the Tisza River. Distributional patterns and habitat preference of three Gammarus species were described by self-organizing map methods and regression tree analysis (CART) on spatial and temporal scale. Using SOMs helped us bring out distinctions in our data and enhance the differences, thus making them easier to recognize and also, with their help, we were able to model the relations of the species to habitat types that were non-existent among our samples. According to the analysis, Gammarus roeselii preferred low altitudes, high conductivity, fine substrate, deep actual mean depth and dense plant coverage; Gammarus fossarum preferred rocky stream beds, high altitudes, lower temperatures and little actual mean depth; while Gammarus balcanicus preferred coarse substrate, little or no plant coverage and low temperatures. SOMs improved the correlations that proved to be highly useful: besides their use in displaying complex data in a perspicuous way, they have other advantages in bringing out existing relationships in data that would otherwise be difficult to detect.

Effective discharge in Rocky Mountain headwater streams

Summary Whereas effective discharge ( Q eff ) in mountain streams is commonly associated with a moderate flow such as bankfull discharge ( Q bf ), this study found that the maximum discharge ( Q max ), and not bankfull discharge, is the channel forming or effective flow for gravel transport in plane-bed streams where partial bed mobility causes steep gravel transport rating curves. Q eff may approach bankfull flow in some step-pool channels where gravel moves over a static cobble/boulder bed. Our conclusions are based on magnitude–frequency analyses conducted at 41 gauged Rocky Mountain headwater streams. Because these gauged streams lacked gravel transport data, as is typical, comparable streams with measured transport rates were used to develop scaling relations for rating curve exponents with stream and watershed characteristics. Those scaling relations were then used to estimate the steepness of gravel rating curves at the 41 gauged but unsampled sites. The measured flow frequency distributions were characterized by two fitted power functions. The steepness of the flow frequency distributions and the estimated steepness of gravel transport relations were combined in magnitude–frequency analyses to compute Q eff .

Morphological taxonomy, DNA barcoding, and species diversity in southern Rocky Mountain headwater streams

Elevation gradients allow scientists to observe changes in fauna over a range of abiotic conditions. A variety of trends in aquatic insect diversity patterns across elevation have been reported. However, many of these studies are confounded because they include streams at lower elevations, which are often larger in size and more polluted than their higher-elevation counterparts. Moreover, such studies always relied solely on morphological delineation of taxa, thereby potentially overlooking cryptic diversity. We reduced these limitations by sampling only minimally impacted wadeable streams across an elevation gradient and by combining morphological taxonomy with deoxyribonucleic acid (DNA) barcoding to identify taxa. We collected numerically abundant Ephemeroptera, Plecoptera, and Trichoptera (EPT) from single streams at ∼200-m elevation intervals across >1000-m transects in 3 watersheds draining the eastern slope of the Colorado Rocky Mountains. Based on morphology alone, we identified 49 numerically abundant EPT morphospecies across 26 sites. Using DNA barcoding, we found 69 distinct lineages that probably represent distinct species. EPT species richness was highest at mid-elevations, and rates of turnover along elevation transects showed no consistent elevation trend or trend among ecological zones defined by vegetation. β-diversity across sites at comparable elevations in different watersheds showed a negative trend with increasing elevation that was marginally significant for DNA barcode taxa (p = 0.051) but not for morphospecies. Furthermore, significant (p < 0.05) differences in taxon richness, turnover, and lateral β-diversity values generated by DNA barcoding underscore the ability of molecular tools to quantify patterns in aquatic insect diversity across elevations.

New records of Crossodactylus schmidti Gallardo, 1961 (Anura: Hylodidae) for the state of Rio Grande do Sul, Brazil, with data on morphometry and an updated geographic distribution map

Crossodactylus schmidti Gallardo, 1961 is a diurnal frog inhabiting rocky streams in forested areas, recently considered as a threatened species in the Brazilian states of Rio Grande do Sul and Santa Catarina. Herein we present four new population records of C. schmidti for the northwestern region of Rio Grande do Sul state and discuss the major impacts that may be threatening the species in the state. Additionally, we present an updated map of the current known species distribution and compare morphometric data among populations from Rio Grande do Sul state and Paraná state, in Brazil, and from the province of Misiones, Argentina, based on the examination of voucher specimens available from herpetological collections.

Evolutionary ecology of settlement size in planktotrophic neritimorph gastropods

Body size during larval development is one of the most important attributes of aquatic animals. The optimal size for changing form or habitat may vary according to ecological traits of species, while phylogenetic constraints also play a significant role. The major goal of this study is to reveal the patterns in the settlement size of planktotrophic larvae in an archaic gastropod superorder Neritimorpha. We take advantage of the fact that size at various ontogenetic stages of neritimorphs can be rigorously estimated by measuring features of the adult opercula. This unique feature of neritimorphs has allowed us to generate the largest data set so far on larval settlement sizes within a group of marine invertebrates that recruit into very different post-metamorphic habitats. Eighty-eight species that represent most extant genera from rocky shores, seagrass beds, mangroves, estuaries, streams, submarine caves, deep-sea vents or seeps showed negligible intraspecific variation and considerable interspecific differences in settlement size, particularly between genera or families. Settlement size is determined primarily by phylogenetic constraints, while parallel evolution toward smaller sizes was shown to occur exclusively in four independent clades (two living and two extinct) of amphidromous snails with a marine larval period followed by a limnic adult phase. The smaller settlement size may possibly reduce the risk of being wafted away from the estuaries of their natal streams through less time achieving metamorphic competence, while ability to make occasional long-distance trips is retained by the presence of a sufficiently long delay period. This delay period also seems to obscure the possible correlation between settlement size and geographic distribution range of neritimorph species, both fully marine and amphidromous.

Eastern dobsonfly (adult), hellgrammite (larva) Corydalus cornutus (Linnaeus) (Insecta: Megaloptera: Corydalidae: Corydalinae)

The eastern dobsonfly is one of our largest non-lepidopteran insects. Its larvae, known as hellgrammites, are the top invertebrate predators in rocky streams where they occur. Adult male dobsonflies are particularly spectacular because of their large sickle-shaped mandibles (jaws). This 4-page fact sheet was written by Donald W. Hall and published by the UF Department of Entomology and Nematology, April 2013.&#x0D; http://edis.ifas.ufl.edu/in987

Evaluating levels of genotoxic stress in eastern hellbenders (Cryptobranchus alleganiensis alleganiensis) using the erythrocyte micronucleus assay

The micronucleus assay is a count of cells containing fragments of nuclear content (micronuclei, MN) that arise duringerrorsincelldivisionand when animals are exposed to genotoxic agents such as chemicals or radiation. The assay can be performed (via light microscopy) using any nucleated cell type, such as erythrocytes in amphibians, birds, fish, and reptiles. Most prior studies of MN in amphibians have been performed in laboratory settings. The goal of this project was to determine baseline levels of genotoxic stress (i.e., frequency of MN in erythrocytes) in a free-living popu- lation of eastern hellbenders (Cryptobranchus alleganiensis alleganiensis, a species of giant salamander that lives in rocky streams) in northern Georgia, USA. We obtained and examined blood smears from 51 hellbenders from eight streams during a 3-month survey (June-August) in 2012. Counts of erythrocytes with MN were made from stained thin bloodfilmsandexpressedasapercentageoftotalcellscounted (1,000 per animal). Micronuclei were detected in 1.16 % of erythrocytes on average in the hellbenders, and there was a negative relationship between snout-vent length and MN frequency, indicating an age-related increase in clearance of cells with nuclear damage. This relationship with size should

A Previously Undocumented Locality of Eastern Hellbenders (Cryptobranchus alleganiensis alleganiensis) in the Elk River, Carter County, TN

Abstract Cryptobranchus alleganiensis alleganiensis (Eastern Hellbender) is a large, imperiled aquatic salamander found in rocky upland streams from New York to Alabama. Although widespread, many Hellbender populations are now highly fragmented by impoundments and degraded habitats. Hellbenders likely require specific stream habitats with relatively low anthropogenic impacts in order to maintain population viability. The Elk River is a small (5th order), high-gradient tributary of the Watauga River drainage that originates in Avery County, NC and flows northwest to Watauga Reservoir in northeastern Tennessee. Although the Elk River's headwaters are heavily impacted by development in the resort towns of Banner Elk and Sugar Mountain; its lower reaches flow through portions of the Pisgah and Cherokee National Forests and over several large waterfalls before reaching the reservoir. Hellbender presence was undocumented in the Elk River prior to 2010. We learned that Hellbenders were likely present in the lowe...

Can seasonal differences influence food web structure on preserved habitats? Responses from two Brazilian streams

Many studies on Neotropical streams have reported seasonal changes in the diet of fish, although studies that evaluate the influence of these temporal differences on the entire web are very scarce. Under the hypothesis that trophic interactions and the food web structure are under seasonal influences, two forested streams (named S1 and S2) were sampled during the wet and dry periods. The samplings were conducted in August 2007 and April 2008 and included algae, macrophytes, plankton. macroinvertebrates, and fish. All heterotrophic taxa sampled were submitted to diet analysis. The similarity among samples was estimated by a cluster analysis using quantitative data of environmental variables, community attributes, and food web properties. A total of 2,250 individuals of 139 trophic species were identified. The food webs were mainly detritus-based, which resulted in a great proportion of trophic species at the first trophic level and high omnivory in all samples. All fish species were top species because they had no predators. The S1 stream, predominantly composed of a sandy substrate, presented lower abundance than the predominantly rocky S2 stream in both dry and wet periods, although richness was similar. Cluster analysis demonstrated that environmental attributes were more similar between seasons, community attributes were more similar between streams, and food web parameters were very similar (94% similarity) both between streams and seasons. Therefore, we concluded that although environmental attributes varied temporally and community attributes varied spatially, the trophic relationships and overall food web structure of these preserved streams remain similar.

A new species of Bokermannohyla (Anura: Hylidae) from highlands of Central Brazil

We describe a new species of hylid frog, Bokermannohyla sapiranga sp. nov., from Central Brazil (15°55’49” S,47°52’59” W, 1110m asl). The species is characterized by medium size (males snout-vent length 45.6±4.7mm, N=13; fe-males 46.9±6.2, N=4) for the B. pseudopseudis group and by iris color varying from orange to reddish. The advertisementcall is similar in some aspects to calls of B. pseudopseudis, but differs mainly by structure and spectral features, but alsotemporal ones such as call length, note duration, and number of notes per call. The new species uses streams with muddybeds in gallery forests as well as rocky bed streams in the highlands of Goiás State and Distrito Federal. The new speciesis tentatively included in the B. pseudopseudis group based on shared morphological features, ecology, and behavior. Mor-phometric analysis of size-independent variables indicated that B. sapiranga differs from B. pseudopseudis mostly in head length and width, interorbital distance, and diameter of the fourth toe disc.

Archineura incarnata(Karsch, 1892) andAtrocalopteryx melli(Ris, 1912) in southern China (Odonata: Calopterygidae)

The calopterygines Archineura incarnata and Atrocalopteryx melli are subtropical habitat specialists, endemic to China, and sensitive to environmental change. We identified several sites with environmental deterioration from which the species seem to have disappeared; these species can be used as indicators of human disturbance. In this paper their distribution in China is mapped and information on their habitat is given, based on literature records (from 1892 until 2012) with supplements from field investigations in 2008–2011. We analysed Chinese literature, which contained much useful information. In all, 57 sites in 12 provinces were found to contain the two species. Suitable habitats occur in small shaded headwater streamlets for A. melli, in rocky streams for Ar. incarnata. The ranges of both species form an arc that descends from 30°N, then in the east curves inland at the level of the tropic. Archineura incarnata is clearly the more common species, but both are perhaps not so rare as hitherto belie...

A new species of Leptolalax (Anura: Megophryidae) from Laos

We describe a new species of megophryid frog in the genus Leptolalax from southern Laos. Leptolalax aereus sp. nov. is distinguished from its congeners by a combination of size (25.1–28.9 mm in 28 adult males, 27.1–38.6 mm in 12 adult females), absence of distinct black or dark brown dorsolateral markings on head, near immaculate white chest and belly, head length greater than head width, no webbing or lateral fringing on fingers, rudimentary webbing between toes I–IV and no webbing between toes IV–V, toes with weak lateral fringing, and a call consisting of an average of 3–4 notes containing 1–2 pulses, and with a dominant frequency of 6187.5–7875 Hz. The new species is associated with rocky streams in semi-evergreen and evergreen forest between 284–511 m elevation.

A new species of Leptolalax (Anura: Megophryidae) from Vietnam and further information on Leptolalax tuberosus

We describe a new species of megophryid frog from central Vietnam. Leptolalax croceus sp. nov. is most similar to L. tuberosus, but distinguished from this and all other Leptolalax species by its bright orange belly in life and by its unique, complex advertisement call consisting of 4–6 variably pulsed notes with a dominant frequency of 2635–3000 Hz. In contrast, L. tuberosus has an advertisement call consisting of a single, weakly pulsed note lasting 54–78 ms with a dominant frequency of 2584–2756.2 Hz. Leptolalax croceus sp. nov. can be further distinguished from its congeners by a combination of an indistinct tympanum, highly tuberculate dorsum, medium body size (22.2–27.3 mm in 16 adult males), head slightly wider than long, rudimentary webbing between toes I–III, no webbing between toes III–V, no lateral fringing on toes, and no ventrolateral glands. The new species is only known from a single locality in evergreen forest at 1316 m elevation. Males were found calling from leaf litter and low vegetation adjacent to a shallow, rocky stream. We suggest the species should be considered Data Deficient following IUCN’s Red List categories.

Description of the Tadpole of Bokermannohyla martinsi (Anura: Hylidae), Morphological and Ecological Comparison with Related Bokermannohyla Tadpoles

The Bokermannohyla martinsi species group includes two species, B. martinsi and B. langei. Bokermannohyla martinsi is found mainly in rocky permanent streams, associated with gallery forests in the highlands of the southernmost portion of the Espinhaco Mountain Range, Brazil. Its tadpoles have robust, oval/ovoid in lateral and dorsal views, black bodies, and a muscular tail. External morphology, color in life and in preservative, and detailed morphometric data are presented, as well as natural history notes for the species. Diagnostic characteristics that help distinguish B. martinsi tadpoles from other species within the B. circumdata, B. pseudopseudis, B. alvarengai, and B. claresignata groups are as follows: labial tooth row formula, absence of a median gap on the anterior row of marginal papillae, and black coloration of the body and tail. Data on microhabitat use available for five species of Bokermannohyla indicate that their tadpoles have broad niches, being able to exploit many types of microhabitats (e.g., substrate type, depth, current, and vegetation presence or absence) throughout the year within the streams where they occur. Regardless of the available microhabitats in the sampling sites, tadpoles showed high niche overlap, rendering their differentiation based on microhabitat use unlikely.

A new species of Leptolalax (Anura: Megophryidae) from northeastern Cambodia

We describe a new species of megophryid frog in the genus Leptolalax from the Kon Tum Plateau in northeastern Cambodia. Leptolalax melicus sp. nov. is distinguished from its congeners by a combination of an off-white to pale pink ventral surface with diffuse dark brown blotches and distinct white speckling, finger I &lt; II, an absence of webbing and dermal fringes on fingers, slight basal webbing and no dermal fringes on toes, body size (19.5–22.7 mm for seven adult males), an absence of ventrolateral glandular lines, dorsum mostly smooth with no skin ridges, and a unique advertisement call consisting of a single long introductory note containing 8–50 pulses, followed by 3–11 predominantly single-pulsed notes, and with an average dominant frequency of 3560–3610 Hz. Leptolalax melicus can be further distinguished from the morphologically similar L. applebyi in having more distinct dorsal patterning, and significantly larger pectoral and femoral glands. Leptolalax melicus and L. applebyi also differ by 6.1% sequence divergence at the 16S mtDNA gene. All specimens of L. melicus were found near rocky streams in evergreen forest between 650–850 m elevation. We suggest the new species should be considered Data Deficient following IUCN’s Red List categories.

A Novel Technique for Mapping Habitat in Navigable Streams Using Low‐cost Side Scan Sonar

An inexpensive and rapid technique for mapping instream habitat of navigable rivers is needed by natural resource professionals. Unlike more expensive side scan sonar devices, the Humminbird® Side Imaging system employs a boat‐mounted transducer enabling the survey of shallow, rocky streams. This device can be used to obtain high resolution, georeferenced images of underwater habitat. We developed a technique employing geographic information systems (GIS) to transform raw sonar images to fit the configuration of a stream channel. The end product is a GIS layer that can be interpreted to map instream habitat. We demonstrated this approach by mapping substrate and large woody debris in a southwest Georgia stream, and evaluated the technique through a comprehensive accuracy assessment. An overall classification accuracy of 77% was observed for substrate mapping and sonar estimates of large woody debris were correlated (r2 = 0.79) with actual wood abundance. Sonar mapping generated estimates of reach and substrate area comparable to a traditional field approach, and reduced the time investment by 90%. Applications for high resolution habitat maps are widespread and numerous; the ability to produce these maps at low cost is now within the grasp of researchers and managers alike.

Anomaloglossus confusus, a New Ecuadorian Frog Formerly Masquerading as “Colostethus” chocoensis (Dendrobatoidea: Aromobatidae)

Anomaloglossus confusus, new species, is a small (21–26 mm SVL) riparian frog from the Pacific versant of the Andes in northwestern Ecuador. It inhabits rocky forest streams in an elevational range of about 600–1540 m. It is the only known Anomaloglossus in Ecuador, where it can be distinguished from all other dendrobatoids by the generic synapomorphy of a median lingual process. The only other named trans-Andean species of Anomaloglossus are the western Colombian A. atopoglossus and A. lacrimosus. Anomaloglossus confusus was previously confused with ‘‘Hylixalus’’ or ‘‘Colostethus’’ chocoensis (currently in Hyloxalus), a rare species described by Boulenger on the basis of a subadult female from Pacific lowland Colombia. The first adult specimen of Hyloxalus chocoensis, an adult male, is described. The generic name Hylixalus is not ‘‘an incorrect subsequent spelling’’ as recently interpreted, but an emendation with its own authorship and date of publication (Boulenger, 1882); as such, it is a junior objective synonym of Hyloxalus and is an available name.