River Drainage Research Articles

Water Resources, Pollution, Integrated Management and Practices in Nigeria – An Overview

This paper provides a comprehensive overview of Nigeria’s water landscape, focusing on its abundant surface and underground water sources and the agencies responsible for water resources development and management. Findings reveals that the country boasts vast freshwater reserves, encompassing surface and groundwater, intricate river drainage systems, numerous dams, and managed aquifer formations, primarily overseen by River Basin Development Authorities. Despite these resources, Nigeria faces severe pollution challenges, especially in the Niger Delta, resulting from oil-related activities and causing environmental degradation, health crises, and enduring ecosystem consequences. Approximately 13 million barrels of oil spills have adversely impacted coastal wetlands, mangroves, and agricultural lands. Elevated levels of heavy metal pollution, exceeding recommended guidelines, pose significant threats to public health, emphasizing the lasting impact of persistent oil spillage on fishery production and aquatic organisms. River Basin Development Authorities have made substantial contributions, challenges persist in catchment management and the indiscriminate disposal of hazardous substances. The absence of effective environmental policies necessitates urgent, coordinated action from federal and state governments. Nigeria must prioritize integrated water management practices to strike a delicate balance between resource utilization and preservation for the benefit of current and future generations. This manuscript relies on secondary sources, utilizing key search terms such as “water resources in Nigeria,” “water pollution in Nigeria,” “water supply and demand in Nigeria,” “water management in Nigeria,” and “integrated water practices in Nigeria.” Data were sourced from reputable institutions, including the Federal Ministry of Water Resources, The World Bank, United Nations Environmental Protection (UNEP), USAID’s Sustainable Water Partnership, and various scientific publications, ensuring the reliability of the presented data.

A new characid species with remarkable sexual dimorphism (Characiformes: Characidae: Stevardiinae) from the upper Guayabero River, Orinoco basin, Colombia.

A new species of characid with remarkable sexual characteristics is described from the upper Guayabero River drainage from the Orinoco basin in Colombia. The new species is included in the genus Monotocheirodon by sharing most of the previously proposed diagnostic features of this genus. It differs from all Stevardiinae by the combination, in adult males, of an enlarged urogenital papilla in contact with the first anal-fin unbranched ray and a highly modified anal fin with enlarged and distally elongated first and second branched anal-fin rays, forming a gonopodium-like structure. In addition, it differs from congeners by the presence of an adipose fin, an incomplete lateral line, an ascending process of the premaxilla dorsally oriented, and a long snout. The new species was discovered from a poorly sampled region in Colombia and is an unexpected new record given its disjunct geographic distribution from other species of the genus. Monotocheirodon species were previously known from piedmont drainages in Bolivia and Peru. The conservation status of the new species is herein categorized following IUCN criteria.

Calibration, validation and uncertainty analysis of a SWAT water quality model

Sediment and nutrient pollution in water bodies is threatening human health and the ecosystem, due to rapid land use changes and improper agricultural practices. The impact of the nonpoint source pollution needs to be evaluated for the sustainable use of water resources. An ideal tool like the soil and water assessment tool (SWAT) can assess the impact of pollutant loads on the drainage area, which could be beneficial for developing a water quality management model. This study aims to evaluate the SWAT model’s multi-objective and multivariable calibration, validation, and uncertainty analysis at three different sites of the Yarra River drainage area in Victoria, Australia. The drainage area is split into 51 subdrainage areas in the SWAT model. The model is calibrated and validated for streamflow from 1990 to 2008 and sediment and nutrients from 1998 to 2008. The results show that most of the monthly and annual calibration and validation for streamflow, nutrients, and sediment at the three selected sites are found with Nash–Sutcliffe efficiency values greater than 0.50. Furthermore, the uncertainty analysis of the model shows satisfactory results where the p-factor value is reliable by considering 95% prediction uncertainty and the d-factor value is close to zero. The model's results indicate that the model performs well in the river's watershed, which helps construct a water quality management model. Finally, the model application in the cost-effective management of water quality might reduce pollution in water bodies due to land use and agricultural activities, which would be beneficial to water management managers.

Redescription of Cyprinion muscatense (Teleostei: Cyprinidae) with the first phylogenetic analysis of the genus.

Members of the genus Cyprinion (Cypriniformes: Cyprinidae) are found in the Indus River basin west to the Arabian Peninsula and the Tigris-Euphrates River drainages (Persian Gulf basin). The taxonomic status of Cyprinion including Cyprinion muscatense is poorly understood when compared to other cyprinid genera. C. muscatense has been considered as a member of the Cyprinion watsoni-microphthalmum group and a valid species endemic to the Arabian Peninsula. Here, we redescribe C. muscatense based on an integrative morphological and molecular approach and freshly sampled material from several localities in the Oman Mountains ecoregion. The results showed that C. muscatense is distinguished from the other Cyprinion species in the Arabian Peninsula by having a short, thin, and slightly serrated last unbranched dorsal fin ray; the lower number of circumpeduncular scales; lateral line scales; and also scales between the lateral line and the dorsal-fin origin. Subterminal mouth, presence of one pair of small barbels at the mouth corner, 3-4 unbranched and 9½-10½ dorsal-fin branched rays, 12-14 pectoral-fin rays, 7-8 pelvic-fin rays, 2-3 unbranched and 6½-7½ branched anal-fin rays, and 37-40 lateral line scales are other morphological characteristics of C. muscatense. C. muscatense is also well distinguished by molecular characters among its congeners. The first molecular phylogenetic analysis of the genus, covering all currently recognized Cyprinion species except for C. watsoni, is also presented. C. muscatense is resolved as the sister species to another endemic fish of the Arabian Peninsula Cyprinion mhalense, with a Kimura-2-Parameter model distance of 5.3%.

A review of Appalachian Dasycerus Brongniart and the recognition of cryptic diversity within Dasycerus carolinensis (Coleoptera: Staphylinidae: Dasycerinae)

Abstract Previous analyses have revealed deep divergences among populations of the relictual and enigmatic rove beetle, Dasycerus carolinensis Horn. New data from additional populations, molecular markers, and morphology unambiguously reveal this “species” to represent a complex of closely related species, distinguishable by characters of the male genitalia and corresponding closely to geographically coherent clades discovered by molecular analyses. Calibrated dating analyses show Appalachian Dasycerus to have been diverging in the region for more than 10 million years, yet largely respecting important biogeographic barriers in the region, such as the French Broad and Little Tennessee River drainages. In addition to discussing finer scale biogeographic patterns in the group, we formally recognize 9 new species from within what was formerly known as Dasycerus carolinensis: Dasycerus virginiensis sp. nov., Dasycerus tuckasegee sp. nov., Dasycerus pacolet sp. nov., Dasycerus chattooga sp. nov., Dasycerus itseyi sp. nov., Dasycerus unicoi sp. nov., Dasycerus nikwasi sp. nov., Dasycerus egwanulti sp. nov., and Dasycerus gadalutsi sp. nov. It was not, however, possible to assign all samples to one of these species, and specimens from some sparsely sampled outlying areas, northern Alabama and central Tennessee in particular, may represent additional species.

A Pliocene lacustrine system in the Nellis basin, southern Nevada, USA: implications for the Colorado River drainage system

ABSTRACT Lacustrine basins and the sediments in them provide a critical component of regional tectonic development and climate history. Each sub-basin in the landscape records the interplay between active tectonism and shifting climate. Many of the basins in southern Nevada that contain deposits of the Muddy Creek Formation were closed fluvio-lacustrine systems during the latest Miocene and into the Pliocene. They were subsequently integrated into the regional Colorado River system. Lacustrine deposits of the Muddy Creek Formation are exposed along the trace of the Las Vegas Valley shear zone in the Nellis Dunes Recreation Area (NDRA), northeast of Las Vegas, Nevada. The Muddy Creek Formation in NDRA consists of approximately 130 m of mixed carbonates and clastics, and new tephrochronology suggests an early to late Pliocene age (∼ 4.7 to ∼ 2.6 Ma) for the lowermost lacustrine deposits and an unknown, but younger, age for the uppermost spring-fed lacustrine deposit. These sediments were deposited in an arid to semiarid lake (Lake Nellis) and alluvial floodplain system based on the interpretation of lithologies and facies associations. The stratigraphic succession coarsens upward and reflects establishment of a lacustrine carbonate system overlain by a clastic succession of peripheral lake sediments of alluvial and floodplain origin. The peripheral lake deposits consist of spring-fed and fluvial wetland mudflats of brown claystone and siltstone. This brown claystone is capped by a succession of yellow and red sandstones deposited by fluvial and minor eolian processes. The second, and youngest, freshwater limestone, likely disconformably, overlies the yellow and red sandstones, and is thought to be temporally and depositionally distinct from the underlying Muddy Creek deposits. The transition from the lower lacustrine carbonates to clastic fluvial channel and flood-plain deposits indicates desiccation of Lake Nellis and possibly occurs soon after ∼ 2.7 to ∼ 2.6 Ma based on the ages of tuffs occurring in the uppermost limestone and marl beds. This is consistent with an interpreted increase in regional aridity after ∼ 2.8 Ma (Smith et al. 1993). The second limestone deposit at the top of the section represents an even younger spring-fed lacustrine deposit of unknown age. Throughout the lower carbonate section, three tuffs were identified, and geochemically correlated, using a discriminant-function analysis, to the tuff of Napa (≤ 4.70 ± 0.03 Ma), the Putah Tuff (∼ 3.3 Ma), and the lower tuffs of the Badlands (∼ 2.7 to ∼ 2.6 Ma). The timing of deposition of Lake Nellis sediments postdates the integration of the three major lake systems in this region (Lake Grand Wash, Lake Hualapai, and Lake Las Vegas) into the Colorado River drainage (5.6–4.9 Ma), and also postdates the full integration of the river to sea level (4.8–4.63 Ma) (Howard et al. 2015; Crow et al. 2021). Lake Nellis represents an isolated lake basin that was one, and maybe the last, lacustrine system to be fully integrated into the Colorado River drainage in this region.

Trophic niche drives the evolution of craniofacial shape in Trinidadian guppies.

Diverse clades of fishes adapted to feeding on the benthos repeatedly converge on steep craniofacial profiles and shorter, wider heads. But in an incipient radiation, to what extent is this morphological evolution measurable and can we distinguish the relative genetic vs. plastic effects? We use the Trinidadian guppy (Poecilia reticulata) to test the repeatability of adaptation and the alignment of genetic and environmental effects shaping poecilid craniofacial morphology. We compare wild-caught and common garden lab-reared fish to quantify the genetic and plastic components of craniofacial morphology across 4 populations from 2 river drainage systems (n = 56 total). We first use micro-computed tomography to capture 3D morphology, then place both landmarks and semilandmarks to perform size-corrected 3D morphometrics and quantify shape space. We find a measurable, significant, and repeatable divergence in craniofacial shape between high-predation invertivore and low-predation detritivore populations. As predicted from previous examples of piscine adaptive trophic divergence, we find increases in head slope and craniofacial compression among the benthic detritivore foragers. Furthermore, the effects of environmental plasticity among benthic detritivores produce exaggerated craniofacial morphological change along a parallel axis to genetic morphological adaptation from invertivore ancestors. Overall, many of the major patterns of benthic-limnetic craniofacial evolution appear convergent among disparate groups of teleost fishes.

Local environments, not invasive hybridization, influence cardiac performance of native trout under acute thermal stress.

Climate-induced expansion of invasive hybridization (breeding between invasive and native species) poses a significant threat to the persistence of many native species worldwide. In the northern U.S. Rocky Mountains, hybridization between native cutthroat trout and non-native rainbow trout has increased in recent decades due, in part, to climate-driven increases in water temperature. It has been postulated that invasive hybridization may enhance physiological tolerance to climate-induced thermal stress because laboratory studies indicate that rainbow trout have a higher thermal tolerance than cutthroat trout. Here, we assessed whether invasive hybridization improves cardiac performance response to acute water temperature stress of native wild trout populations. We collected trout from four streams with a wide range of non-native admixture among individuals and with different temperature and streamflow regimes in the upper Flathead River drainage, USA. We measured individual cardiac performance (maximum heart rate, "MaxHR", and temperature at arrhythmia, "ArrTemp") during laboratory trials with increasing water temperatures (10-28°C). Across the study populations, we observed substantial variation in cardiac performance of individual trout when exposed to thermal stress. Notably, we found significant differences in the cardiac response to thermal regimes among native cutthroat trout populations, suggesting the importance of genotype-by-environment interactions in shaping the physiological performance of native cutthroat trout. However, rainbow trout admixture had no significant effect on cardiac performance (MaxHR and ArrTemp) within any of the three populations. Our results indicate that invasive hybridization with a warmer-adapted species does not enhance the cardiac performance of native trout under warming conditions. Maintaining numerous populations across thermally and hydrologically diverse stream environments will be crucial for native trout to adapt and persist in a warming climate.

Monitoring the threatened Harttiella (Siluriformes, Loricariidae) with environmental DNA: A comparison between metabarcoding and targeted digital PCR

Abstract Environmental DNA has emerged as an efficient alternative to traditional sampling methods. A standard multispecies or a targeted single‐species approach can be used for analysing environmental DNA samples. The costs, benefits, and drawbacks associated with these two approaches are quite different. Here, a comparison between standard multispecies metabarcoding and targeted species assay using digital PCR (dPCR) for two threatened Harttiella species occurring in French Guiana (Harttiella lucifer and H. nsp. “Makwali”) was performed. Samples were collected in 11 sites of the upper Maroni River drainage basin and located in the Galbao mountain range, known to host the targeted species. The “Teleo” primer was used for the metabarcoding approach. To implement a new dPCR assay, specific primers and probes for the two targeted Harttiella species were developed. This targeted dPCR assay detected Harttiella in seven sites. All of these sites were also positive for metabarcoding detection, and the habitat characteristics were favourable for the species. This study demonstrated that both targeted (dPCR) and multispecies (metabarcoding) approaches can be used for the monitoring of the threatened H. lucifer and H. nsp. “Makwali” species. From a conservation point of view, we recommend to use the metabarcoding approach to update the spatial distribution of the species, while the dPCR method can be used for a temporal follow‐up of known Harttiella populations.

A Critical Appraisal of the Sensitivity of Detrital Zircon U–Pb Provenance Data to Constrain Drainage Network Evolution in Southeast Tibet

AbstractProvenance tools, particularly detrital zircon U–Pb analysis, have been widely employed to test drainage network evolution in southeast Tibet and its linkage with the growth of the Tibetan Plateau. Numerous provenance studies have been conducted on the sediments in the paleo‐Yangtze and paleo‐Red River drainage basins. Nevertheless, it is still hotly debated as to whether a “Mississippi” (dendritic) pattern Greater paleo‐Red River, originating from southeast Tibet and draining to the South China Sea, existed in the early Cenozoic, and was subsequently captured by the paleo‐lower Yangtze due to uplift of southeastern Tibet. In this study, in addition to presenting new data from the Gonjo and Jianchuan basins along which the Greater paleo‐Red River is proposed to have flowed, we compiled all the published detrital zircon U–Pb data from the paleo‐upper Yangtze and paleo‐Red River drainage basins from Triassic and younger rocks. Our large database of detrital zircon U–Pb analyses shows that the different terranes in the paleo‐upper Yangtze and paleo‐Red River drainage basins have similar zircon U–Pb signatures since the Late Triassic closure of the Paleo‐Tethys Ocean. Therefore, most of the sediments in the Cenozoic sedimentary basins in southeast Tibet could have been either deposited by long‐distance transport in large rivers from southeast Tibet or recycled from local bedrock. Given the potential importance of sedimentary recycling that we have demonstrated, this poses challenges to the use of detrital zircon U–Pb analyses to determine paleodrainage in this region. We therefore further explored the previously relatively limited use of Sr–Nd isotopes on mudstones and detrital mica 40Ar/39Ar ages, with new analyses from the Gonjo and Jianchuan Basins, to determine if these techniques were better suited to reconstruct paleodrainage evolution. Whilst these techniques do show some promise, more analyses and strategic sampling are required to obtain a full understanding of the extent of their potential utility. Overall, our integrated provenance study indicates that the available data are not sufficiently conclusive to support or refute the Greater paleo‐Red River capture model.

Evolution of the Júcar-Cabriel fluvial system on the Mediterranean watershed of the Iberian Peninsula (Valencia, eastern Spain)

This study presents the characterization and chronology of the Quaternary terrace sequence developed in the confluence zone of the Júcar and Cabriel river valleys. The study area covers a radius of 10 km from the confluence of the two valleys near the locality of Cofrentes (Valencia). It is located in the northern zone of the Ayora-Cofrentes Graben in the northeastern sector of the External Prebetic Zone adjacent to southern Iberian Chain. This N-S graben is an inherited tectonic feature with an axial salt wall subject to different periods of fluvial dissection and refilling since at least the end of the Messinian Salinity Crisis (MSC). Regional isostatic uplift and local uplift and subsidence processes related to salt flow and dissolution during the Quaternary period, favored by fluvial entrenchment and terrace development. The terrace system and the previous pre-incision erosional and depositional surfaces are analyzed from a geomorphological point of view. The terrace system only develops within the soft Mio-Pliocene sedimentary fill of the graben, whilst upstream and downstream this zone the studied valleys develop important gorges (canyons) carved in the Cretaceous tablelands (Caroch Massif) and Mio-Pliocene deposits (Llanura Manchega). The geochronological control is established from 20 numerical ages obtained by different dating methods, such us Electron Spin Resonance (ESR), Optically Stimulated Luminescence (OSL) in detrital sequences and Th/U series in calcareous tufa deposits. Additionally, four K/Ar dates available for volcanic materials disrupting the upper and oldest terrace have been considered. A total of 14 terrace levels were identified between +130–135 m (T1) and +3–4 m (T14) of relative height above the river thalwegs. The T1 has an approximate age of c. 1.6–2.0 M.a. as indicate the age of the volcanic materials from the Agras Volcano intruded in the terrace, marking the onset of Quaternary fluvial dissection in the zone. The obtained geochronological data indicate that the Lower-Middle Pleistocene boundary is slightly above T6 (+60–65 m), which has an ESR age of 577 ± 43 ka. This terrace also documents the onset of the most important period of rise of the salt within the graben interfering drainage development. The geochronological data indicate the occurrence of a second eruptive event during the second half of the Middle Pleistocene related to the terraces T7 (+50 m) and T8 (+35–40 m), updating the volcanic activity in the zone. The beginning of the Upper Pleistocene is recorded by the top sequences of the T9 terrace (+25–30 m) where numerous OSL and Th/U data have been obtained with ages between ca. 105 and 81 ka (MIS 5). However, these young terraces (T8 to T13) are thickened (8–10 m) recording Middle Pleistocene sediments in their basal sequences with ages between ca. 193 and 137 ka (MIS 6). The study provides important data on valley evolution under the interference of volcanic activity, salt –related deformation (diapirism, solution subsidence) and fluvial incision fostered by the rise of the axial diapir (salt wall) protruding the graben since at least the Brunhes-Matuyama boundary. The analyzed fluvial evolution documents interesting cases of river capture, drainage antecedence and tectonic adaptation of the drainage throughout the Quaternary Period. The paper also poses interesting geochronological data on the long-term Quaternary evolution of Mediterranean valleys in the Iberian Peninsula, poorly explored to the date.

Identifikasi Unsur Penyusun Sedimen Sungai Klagison Kota Sorong Papua Barat Daya Menggunakan Metode X-Ray Fluorescence (XRF)

The Klagison River is one of the rivers in Sorong City, West Papua. Surface mining activities occur in the Klagison River drainage area which is one of the causes of changes in the geomorphological conditions of the Klagison River. to identify the constituent elements of the Klagison River sediment using X-Ray Fluorescence (XRF). Determination of sampling points using the purposive sampling method and sediment collection tools using the Ekman grab. The method for analyzing sediment constituent elements uses the XRF (X-Ray Fluorescence) method. Based on the research results, there are various types of elements contained in the Klagison River sediment, namely the elements Al, Si, P, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Rb, Sr, Zr and Re. The dominant metal element concentrations from the 5 observation stations are the elements Fe>Si>Cl>Al>Ca>Ti. At observation station 5, the elements Fe>Si>Cl>Al>Ca>Ti are highest compared to the other 4 observation stations, this is because station 5 is the estuary of the Klagison River so it is the last place where liquid waste settles

Grazing preferences of three species of amoebae on cyanobacteria and green algae.

Twenty species/isolates of cyanobacteria and green algae were isolated from cyanobacterial bloom samples in lakes associated with the upper Qu'Appelle River drainage system in southern Saskatchewan, Canada. Three amoebae species (Cochliopodium sp., Vannella sp. and Vermamoeba vermiformis) were also isolated from one of these samples, and were subjected to grazing assays to determine which species of cyanobacteria or algae could potentially serve as a food source. Amoeba grazing rates were quantified based on the diameter of the plaque after 12 days on agar plate assays, and by estimation of the amoeba population growth rate from the rate of increase of plaque area. The common cyanobacterial bloom-formers Dolichospermum sp. and Aphanizomenon flos-aquae supported high growth rates for all three amoebae, while green algae, with the exception of one green alga/amoeba combination, did not support growth of the tested amoebae. Many of the cyanobacterial and algal isolates that did not support amoebae growth were ingested, suggesting that ingestion did not determine grazing success. Overall, while the cyanobacteria Dolichospermum sp. and Aphanizomenon flos-aquae were suitable food sources for the amoebae, the other cyanobacteria were grazed in an unpredictable manner, with some species/strains grazed by some amoebae and some species not grazed at all.

Flood management analysis in the Ngasinan River, Trenggalek Regency, Indonesia

Flood event occurs during the rainy season when water volume increases because rainwater flows through the water channel; due to water volume being larger than the water channel capacity, this event can cause flood inundation through residential areas. The Ngasinan catchment at Trenggalek Regency experienced a flood event that affected thousands of lives in October 2022, to reduce the impact of future floods, this study objective carried out recommendation plans for flood management in the Ngasinan River. The Ngasinan catchment hydrology, maximum annual rainfall from 230.0 mm to 585.0 mm, flood discharge design for the Ngasinan river (river length 21.73 km as main river drainage) are Q25 = 318.64 m3/s, Q100 = 394.96 m3/s. Hydraulic simulation using flood discharge design Q25 -Q100 showed that flood occurs in Ngasinan River sections especially those without embankments or at lower river elevations and cross-sections. Recommendation plans for the Ngasinan River flood management are river normalization, river embankment repairs, residential drainage system, and construction of dams/reservoirs/retarding basins, expected to restore the river’s storage capacity due to sedimentation and destructive flood discharge also to reduce flood discharge, protect river channel banks against flood discharge, and prevent overtopping water into nearby land.

Population Genetic Differentiation of Walleye (Sander vitreus) across the Eastern Highlands of the United States

Walleye is an important sportfish across eastern North America, is commercially fished in the Laurentian Great Lakes region, and has been introduced outside its native range. Thirty-eight Walleye populations within six watersheds across the Eastern Highlands and other portions of the native range were screened at eight microsatellite DNA loci to better understand evolutionary history and to inform fishery management and conservation efforts. Population genetic variation showed divergent assemblages of populations, respectively, living in the Mobile Bay, Mississippi River, Eastern Highlands (Tennessee, New, and Ohio Rivers), and Great Lakes drainages today. All estimates of effective numbers of breeding individuals were under 25, and all populations within all watersheds had ~15–20% inter-individual relatedness, likely attributable to the effects of both natural demographic processes and stocking. The extent of Eastern Highlands Walleye includes both the Ohio and Tennessee River basins.

Molecular and morphometric data provide evidence of intraspecific variation in shape and pigmentation pattern in Otocinclus cocama (Siluriformes: Loricariidae) across major river drainages.

Otocinclus cocama, a uniquely colored species of the loricariid catfish genus Otocinclus described solely from the type locality in the lower Ucayali River in northern Peru, is reported occurring in the Tigre River, a tributary to the Marañón River that drains a different section of the Andean Mountain range in the western Amazon. Both populations differ in the number of dark bars spanning the flanks of the body, and we investigated whether these morphotypes constitute distinct species. The body shapes of populations from the Tigre and Ucayali rivers were compared using geometric morphometrics. Although principal component analysis detected a broad overlap between populations, multivariate analysis of variance and linear driscriminat analysis revealed a subtle differentiation between the populations of the two hydrographic basins. Average body shape of the Ucayali River population tend to be slightly higher than that of the Tigre River, with the caudal peduncle stretched vertically in the Ucayali population. Multivariate regression of shape and centroid size revealed an allometric effect of 10.7% (p < 0.001), suggesting that the variation between Tigre and Ucayali populations was purely shape variation. Molecular data of coI, cytb, nd2, and 16S mitochondrial genes indicated a nucleotide diversity range from 0.001 to 0.003, and haplotypic diversity range from 0.600 ± 0.11 to 0.79 ± 0.07. The median-joining haplotype network for the concatenated matrix exhibited two divergent haplogroups related to the geographic area and separated by <10 mutational steps. The molecular species delimitation methods based on distance (automatic barcode gap discovery and assemble species by automatic partitioning) recovered two molecular lineages evolving independently, being one of the lineages formed by individuals from both populations. Tree-based methods (generalized mixed Yule coalescent and Bayesian implementation of the Poisson tree process) recovered similar topologies and supported single lineage recognition. Methods of molecular delimitation of species disclosed the high similarity between the two populations of Otocinclus cocama, further supported by the presence of old haplotypes common to both groups which could indicate that the populations still maintain gene flow. Although the morphological data reveal a subtle variation between both river basins, the molecular data suggest a weak population structuration based on hydrographic areas, but not different species lineages, therefore Otocinclus cocama is composed of a single lineage with two distinct morphotypes.

A new distinctively striped species of bushynose catfish (Siluriformes: Loricariidae: Ancistrus) from the Pachitea River drainage, Pasco, Peru.

With 76 currently valid species, the bushynose catfish genus Ancistrus is the fourth most species-rich catfish genus, yet Ancistrus diversity remains underestimated, with many species still undescribed. This is especially true of the Peruvian Andean headwaters of the Amazon, which are rich in unnamed Ancistrus species but have received little recent taxonomic attention. We describe a distinctively striped new Ancistrus species from tributaries of the Palcazú River, in the Pachitea-Ucayali-Amazonas drainage basin. The new species differs from all congeners by having black, vermiculated lines covering the head and two to four distinct black, parallel, lateral body stripes from head to caudal fin (vs. body uniformly colored or with dark or light spots or blotches over head and body, or black vermiculate lines on flanks). The new species is the fifth valid species of Ancistrus described from the rich Ucayali River ichthyofauna. It has previously been recognized in the aquarium fish trade as L267.

Estimating the impact of cover crop adoption on ambient nitrogen concentration in the upper Mississippi River drainage

AbstractWe examine cover crop (CC) adoption to determine how this soil health practice has influenced agricultural non‐point source pollution. We use remotely sensed data on practice adoption, and control for hydrological flow direction, weather, and land use to estimate the ex post impact of CC on total Nitrogen concentrations in surface water while controlling for pollutant spillovers from upstream. At the mean treatment level in the study area (3.2%), a 1% increase in CC adoption results in a 0.06 mg/L (2%) reduction in concentration in the study area. Results provide novel estimates based on observed data that can be compared to biophysical simulations of CC effectiveness.

English

Abstract Comprehensive surveys are critical to conserve and monitor crayfish communities, imperiled species, and detect crayfish invasions. The Missouri portion of the North Fork White River drainage (MONFWR) was never comprehensively surveyed, but adjacent drainage surveys suggested it could harbor species of conservation concern (SOCC). We surveyed the MONFWR to determine crayfish species richness, distributions of potential SOCC, and potential invasive species. We included recent sampling of the Arkansas portion of the drainage for a more holistic assessment of the entire drainage. We examined potential changes in crayfish communities after three decades at 22 previously sampled MONFWR locations. We also collected the first habitat association data for the endemic, Faxonius longidigitus. We detected eight taxa; none that were not known from the drainage. Faxonius neglectus chaenodactylus and Cambarus hubbsi were SOCC; F. n. chaenodactylus was common and abundant in the MONFWR; C. hubbsi was detected at only one site in Arkansas. Faxonius neglectus neglectus and Faxonius virilis were each detected only once and are likely introduced. Intermittent streams harbored diversity and abundance rivaling perennial segments. We observed no notable temporal differences between 22 historical and current samples. Faxonius longidigitus, detected at few sites in low numbers, was associated with deeper waters and larger substrates.

Changes in the Active Drainage Network and Their Impact on the Hydrological Response and Flood Risk Management Process: A Case Study for a Flysch Mountain Catchment

The active drainage network (ADN), as a dynamic component of a catchment, plays an important role in a catchment’s functioning. Changes in the ADN are the most noticeable during extreme hydro-meteorological events, and they result from, among others, the incorporation of man-origin incisions into the ADN. Knowledge of the parameters of the “real” ADN is a key element in the field of catchment hydrology because the ADN affects the intensity of hydro-, geomorpho-, and biological processes. The goals of this study are to assess (1) the changes in the ADN during extreme hydro-meteorological events (with special attention paid to the human-induced impact on the ADN transformation) and (2) the consequences of the ADN changes on the hydrological response of a catchment and their impact on the flood hazard/risk management processes. The study was performed in a mountain catchment, prone to flash flood occurrences. The ADN was reconstructed with the use of ALS-LiDAR data using GIS tools, and the hydrological response was evaluated by using SCS-CN and GIUH models. The results revealed that the ADN functioning during heavy rainfalls is three to four times denser than the natural-origin river drainage network (RDN) (11.4 km·km−2 vs. 2.9 km·km−2), and the RDN is significantly modified by human-origin elements (e.g., roads, ditches, furrows, etc.—they constitute ca. 1/3 of the ADN). Moreover, significant structural changes in the ADN have occurred, which were confirmed by the Hortonians’ type of analysis. The changes in the ADN have affected the hydrological response of the catchment (predominantly an increase in the peak flow—up to 7%) and the dimensions of the 1% probable flood hazard zone (increase of ca. 5%). It may be concluded that significant changes in the ADN, in the catchment studied, had a moderate impact on the changes in the flood hazard level. The results give a new insight into the flood hazard/risk assessment processes in a small flysch mountain catchment.