Artykuły w czasopismach na temat „Freshwater streams”
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Mascareñas, Doreen, Roy de Leon i Efren Delos Reyes. "Watershed and Pahu-anCave Stream Interconnectivity in Bonliw, Torrijos, Marinduque, Philippines". Environments 6, nr 2 (24.01.2019): 11. http://dx.doi.org/10.3390/environments6020011.
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Marinduque Island is characterized as having a karst landscape with caves having underground streams harboring a variety of freshwater organisms including freshwater shrimps which are dependent on the quality of the forest and watershed. This study aimed to characterize the forest cover overlying the cave, siltation/sedimentation rate in the surface and cave streams, nutrient contents (ammonium, phosphate. and sulfate) of the sediment and water, and freshwater shrimps and phytoplanktons present in both streams. Results of the assessment indicate that the surface stream and the cave stream in the Torrijos Watershed Forest Reserve are interconnected as shown by both streams having similar freshwater shrimps and phytoplankton species. Phytoplanktons to develop will need sunlight which is devoid in the cave, and therefore have to be transported to the caves to be present. The freshwater shrimps found in the cave are not troglobitic and therefore has found its way to the cave stream. Further, there seemed to be a similar trend on the total suspended solids, sedimentation rates and amount of nutrients (phosphates) between the two streams. Although organic matter and nutrients from the aboveground landscape are needed for the sustenance of organisms in the cave ecosystem (the abundance of which are dependent on the connectivity of the two water systems), siltation/sedimentation can ultimately threaten the water quality of cave stream. With the forest in the watershed area characterized as denuded, the threat is evident. The protection of the watersheds and its landscape is imperative.
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Hawes, Ian, i Paul Brazier. "Freshwater stream ecosystems of James Ross Island, Antarctica". Antarctic Science 3, nr 3 (wrzesień 1991): 265–71. http://dx.doi.org/10.1017/s0954102091000329.
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The freshwater streams of James Ross Island share many of the features common to other Antarctic streams. There is a diel variation in temperature and discharge, which follows the daily insolation cycle; catchments are barren; stream vegetation is predominantly algal, comprising mat-forming cyanobacteria and filamentous chlorophytes; and physical factors, particularly turbidity and bed stability are important in determining biomass and composition of algal assemblages. Nutrient concentrations vary from stream to stream and over a diel cycle, with minimum dissolved N in late afternoon. Biomass attained and photosynthetic and respiratory rates are also comparable to those recorded in other Antarctic streams, with low productivity/biomass ratios in perennial assemblages.
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Richardson, John. "Biological Diversity in Headwater Streams". Water 11, nr 2 (21.02.2019): 366. http://dx.doi.org/10.3390/w11020366.
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Headwaters, the sources of all stream networks, provide habitats that are unique from other freshwater environments and are used by a specialised subset of aquatic species. The features of headwaters that provide special habitats include predator-free or competitor-free spaces; specific resources (particularly detrital based); and moderate variations in flows, temperature and discharge. Headwaters provide key habitats for all or some life stages for a large number of species across just about all freshwater phyla and divisions. Some features of headwaters, including isolation and small population sizes, have allowed for the evolutionary radiation of many groups of organisms within and beyond those habitats. As small and easily engineered physical spaces, headwaters are easily degraded by streambank development, ditching and even burial. Headwater streams are among the most sensitive of freshwater ecosystems due to their intimate linkage with their catchments and how easily they are impacted. As a unique ecosystem with many specialist species, headwater streams deserve better stewardship.
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Carr, Jonathan W., i Frederick G. Whoriskey. "The escape of juvenile farmed Atlantic salmon from hatcheries into freshwater streams in New Brunswick, Canada". ICES Journal of Marine Science 63, nr 7 (1.01.2006): 1263–68. http://dx.doi.org/10.1016/j.icesjms.2006.03.020.
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Abstract The escape of juvenile Atlantic salmon from freshwater hatcheries supplying the salmon farming industry may lead to interactions between wild and farmed fish. The scale of this problem, however, has not been examined in detail. We monitored temporal trends in the abundance of escaped juvenile farmed salmon in the Magaguadavic River and Chamcook Stream for several years. In addition, in 2004 we assessed more than 90% of the commercial hatcheries producing salmon smolts located next to freshwater streams in New Brunswick. Escaped juvenile fish were recorded in 75% of the streams electrofished close to hatcheries. Numbers varied by site and year. However, escaped juvenile salmon were found every year at sites near hatcheries in the Magaguadavic River and Chamcook Stream. In the Magaguadavic River, juvenile escapees outnumbered wild salmon parr in most years. These results highlight the need for implementation of a containment strategy for freshwater hatcheries to reduce escapes.
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Bareen, Firdaus-e., i S. H. Iqbal. "The autumn communities of freshwater hyphomycetes in the tributaries of the River Neelum". Canadian Journal of Botany 75, nr 7 (1.07.1997): 1046–60. http://dx.doi.org/10.1139/b97-116.
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Freshwater hyphomycete communities of autumn, based on data generated by three techniques used simultaneously, were richer than those detected by these techniques used singly. The fungal communities in the acidic streams were poorer (28–32 species) than in the circumneutral streams (39–64 species). No significant correlation was found between number of fungal species and pH of the stream water. Combining the data from this study with those of studies by other authors using the same techniques, linear correlation and regression analyses revealed the significant negative correlation between species composition of communities in a stream and its pH. The number of fungal species in assemblages detected by different techniques used singly (e.g., filtration of stream water or examination of foam concentrate) or communities based on data generated by these techniques used simultaneously versus pH values formed a unimodal curve with a maximum at a pH between 6 and 7, mostly at 6.7. The conidial dynamics were influenced by the riparian vegetation. Conidium production from submerged deciduous and conifer litter was determined under laboratory conditions. Generally conidium production per disc was higher for Anguillospora longissima (Sacc. & Syd) Ingold, Flagellospora cumula Ingold, Lunulospora curvula Ingold, and Tetracladium marchalianum de Wildeman in deciduous leaves than conifer leaves. Heliscus lugdunensis Sacc. & Therry, Alatospora acuminata Ingold, and Articulospora tetracladia Ingold produced more conidia per disc in conifer than in deciduous leaves. Percentage similarity between spora produced by submerged substrate and stream spora was higher for deciduous substratum than for coniferous substratum in five circumneutral streams with a riparian vegetation dominated by deciduous trees. This index was higher for coniferous substratum in three acidic streams in which coniferous and deciduous trees were evenly distributed. The fungal communities in the Nosehri, Pathika, and Jabbar Camp streams showed higher values of species diversity than in other streams. Key words: freshwater, hyphomycetes, species diversity.
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Tsang, Ling Ming, Kwok Ho Tsoi, Simon Kin-Fung Chan, Tony King-Tung Chan i Ka Hou Chu. "Strong genetic differentiation among populations of the freshwater shrimp Caridina cantonensis in Hong Kong: implications for conservation of freshwater fauna in urban areas". Marine and Freshwater Research 68, nr 1 (2017): 187. http://dx.doi.org/10.1071/mf15377.
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Freshwater organisms generally exhibit strong genetic structuring. Although understanding the level and spatial distribution of genetic diversity is crucial for conservation management planning, such information has received little attention until recently in highly developed cities where local extinction attributed to habitat destruction and urbanisation is intense. We compared the genetic divergence in mitochondrial COI of the freshwater shrimp Caridina cantonensis collected from 32 sites in Hong Kong, to determine the connectivity among populations and the levels of genetic diversity of the shrimp. We found that shrimp from different streams are genetically highly differentiated and each stream always has its own unique haplotype groups, even though some of the streams are separated only by a few kilometres, indicating very limited gene flow across streams. Moreover, genetic diversity within each stream is very low, usually with a single haplotype dominating the entire population, and genetic differentiation was observed among tributaries from the same drainage. The high genetic diversity of these species over short distances has significant conservation implications because a substantial amount of biodiversity may have already been lost as a result of past development. Careful conservation planning is essential for future development in Hong Kong and other cities.
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Rutherford, I. D., i C. Gippel. "Australia versus the World: do we face special opportunities and challenges in restoring Australian streams?" Water Science and Technology 43, nr 9 (1.05.2001): 165–74. http://dx.doi.org/10.2166/wst.2001.0531.
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Australians do face special opportunities and challenges in attempting to restore or rehabilitate their streams, when compared with Western Europe and North America. Some of these differences arise from the physical and ecological character of our streams, particularly in terms of flow variability, stream power, sediment, vegetation interactions, and nutrient levels. We also have modest resources available per-unit-length of stream, and no massive freshwater fishing industry. These, and many other differences, combine to produce an environment in which it can be slower and more difficult to rehabilitate streams, and we have less confidence in the results. International case studies are tremendously useful but in some cases we need to be circumspect in applying the results directly to Australian streams.
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Wright, I. A., P. J. Davies, S. J. Findlay i O. J. Jonasson. "A new type of water pollution: concrete drainage infrastructure and geochemical contamination of urban waters". Marine and Freshwater Research 62, nr 12 (2011): 1355. http://dx.doi.org/10.1071/mf10296.
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Stormwater and other urban runoff is often conveyed by concrete infrastructure and it is plausible that the chemistry of urban streams is modified by the leaching of minerals from this infrastructure. We tested this hypothesis by analysing major anions, cations and other chemical variables from urban and reference freshwater streams in northern Sydney. Urban streams tended towards neutral pH whereas non-urban reference streams were acidic. Bicarbonate levels were more than 10 times higher and calcium concentrations were more than six times higher in urban streams than reference streams. Experimental analysis revealed that the chemistry of rainwater changed when passed through concrete pipes and down concrete gutters, suggesting dissolution of cement products from various concrete materials used for urban drainage. This study concluded that the use of concrete – particularly its application for urban drainage – is responsible for some of the modifications to urban stream geochemistry. Thus, urban geology should be considered as an important factor that contributes to the urban stream syndrome.
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Diamond, Kelly M., Christopher J. Good, Nina Johnny, Troy S. Sakihara, Paul L. Edmiston, Jennifer A. Faust, Tonya C. Schoenfuss, Alexander M. Rubin, Richard W. Blob i Heiko L. Schoenfuss. "Assessing Occurrence and Biological Consequences of Contaminants of Emerging Concern on Oceanic Islands". Water 14, nr 3 (18.01.2022): 275. http://dx.doi.org/10.3390/w14030275.
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Freshwater streams on oceanic islands serve critical ecological and economic functions. However, these are underrepresented in assessments of pollution from contaminants of emerging concern (CEC). Furthermore, freshwater streams and their endemic fauna often have characteristics that are distinct from those of continental streams and model species, calling extrapolations from studies of such systems into question for island streams. In the current study, we assessed the presence of CEC across three sampling events and five freshwater streams on the Island of Hawai’i. We also exposed juveniles of the native fish species Sicyopterus stimpsoni to a mixture of commonly co-occurring CEC for 96 h in static renewal experiments, testing for impacts of CEC in two ecologically relevant assays of functional performance. CEC from multiple sources were ubiquitous in Hawaiian streams, including human-use pharmaceuticals, agricultural herbicides, and industrial runoff. Concentrations of CEC were comparable to published studies from continental streams, exceeding total concentrations of 1000 ng/L for the eight quantified CEC in four samples, and approaching 2500 ng/L in one sample. Effects on exposed fish were subtle and limited to treatments with higher CEC concentrations but indicated potential impacts of CEC on locomotor performance. These results indicate that Hawaiian streams follow a global trend of widespread freshwater pollution by CEC that are accompanied by subtle effects on native fish species and highlight the need for the inclusion of endemic species and ecologically relevant assays when assessing the effects of contaminants in island habitats.
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Jennings, Jean-Jacques, i Avital Gasith. "Spatial and Temporal Changes in Habitat Conditions in the Na'aman Stream Ecosystem, Israel". Water Science and Technology 27, nr 7-8 (1.04.1993): 387–95. http://dx.doi.org/10.2166/wst.1993.0574.
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Nahal Na'aman is a small, shallow coastal stream in northern Israel. A three year study was conducted to examine the effect of habitat conditions on the biological structure and function of the stream ecosystem. Here we describe temporal and spatial changes in the water regime and water quality as measures of the stream's habitat conditions. Habitat condition is strongly influenced by the hydrological regime and the water quality. In dry years the water level drops and the upper section of the stream may dry up completely. Inflow of polluted water from various sources increasingly reduces water quality downstream. In general, the Na'aman may be categorized as oligo- to mesohaline stream, highly enriched with organic matter and nutrients. Sporadic pollution events markedly affect the water quality resulting in hypertrophic conditions, particularly at times of low stream levels. Low water quality was detected also in association with the drying and refilling of the stream's sections in late summer and in fall, respectively, and following runoff in winter. The oligohaine nature of the stream a priori reduces species diversity relative to other freshwater, lowland streams/Based on water quality conditions, highest species diversity may be expected in the spring area and the upper section of the stream. However, habitat conditions in this section are most unstable due to changes of the hydrological regime. This, in turn, is expected to further reduce species richness and diversity. The extreme conditions are expected to determine the limit for the development of plant and animal life in the stream. This study illustrates the inherent problems of the coastal streams of Israel, namely, diminishing natural flow which is often replaced by discharge of effluent or sewage. Rehabilitation of the Na'aman and other coastal streams demands a radical solution for these problems.
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Gonçalves, Ana Lúcia, Adriana Carvalho, Felix Bärlocher i Cristina Canhoto. "Are fungal strains from salinized streams adapted to salt-rich conditions?" Philosophical Transactions of the Royal Society B: Biological Sciences 374, nr 1764 (3.12.2018): 20180018. http://dx.doi.org/10.1098/rstb.2018.0018.
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Anthropogenic salinization of freshwater is a global problem with largely unknown consequences for stream functions. We compared the effects of salt addition (6 g l −1 NaCl) in microcosms on leaf mass loss and microbial parameters in single- and multispecies assemblages of fungal strains ( Heliscus lugdunensis , HELU; Tetracladium marchalianum , TEMA; Flagellospora curta , FLCU) isolated from a reference (R) or salinized (S) stream. Fungal growth and interactions were also assessed. Salinization inhibited leaf decomposition and fungal biomass, but no differences were observed between species, strains or species combinations. Sporulation rates in monocultures were not affected by added salt, but differed among species (FLCU > HELU > TEMA), with S strains releasing more conidia. Fungal assemblages did not differ significantly in total conidia production (either between strains or medium salt concentration). HELU was the dominant species, which also had highest growth and most pronounced antagonistic behaviour. Fungal species, irrespective of origin, largely maintained their function in salinized streams. Strains from salt-contaminated streams did not trade-off conidial production for vegetative growth at high salt levels. The expected reduction of fungal diversity and potential changes in nutritional litter quality owing to salinization may impact leaf incorporation into secondary production in streams. This article is part of the theme issue ‘Salt in freshwaters: causes, ecological consequences and future prospects’.
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Elias, Carmen L., Ana Raquel Calapez, Salomé F. P. Almeida i Maria João Feio. "From perennial to temporary streams: an extreme drought as a driving force of freshwater communities". Marine and Freshwater Research 66, nr 5 (2015): 469. http://dx.doi.org/10.1071/mf13312.
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Alterations in trait proportions of diatom and aquatic macroinvertebrate communities were used to evaluate the consequences of the drying of temperate perennial streams due to an uncommon drought event. Four Atlantic-temperate Portuguese streams were sampled on three occasions; spring before the drought, 2 weeks after the return of water to the streambed, and spring after the drought. The traits from diatom and macroinvertebrate communities from temperate streams were also compared with those from Mediterranean systems to assess possible shifts in traits. The effects from stream drying were long-lasting for macroinvertebrates; however, only the diatom trait proportions shifted towards proportions similar to those occurring in Mediterranean streams. There was a significant reduction of macroinvertebrates with the ability to produce cocoons, to disperse actively by flight and passively disperse in the water and of swimmers following the return of water. A decrease in stalked species immediately after drought was evident in diatom communities. In contrast to temperate communities, Mediterranean ones were characterised by larger and less mobile diatoms, and smaller-bodied macroinvertebrates with shorter life cycles. Additional studies are required to determine the long-term effect of uncharacteristic drought events on biological traits and their ecosystem functions in typically perennial streams.
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Kaushal, Sujay S., Gene E. Likens, Michael L. Pace, Shahan Haq, Kelsey L. Wood, Joseph G. Galella, Carol Morel i in. "Novel ‘chemical cocktails' in inland waters are a consequence of the freshwater salinization syndrome". Philosophical Transactions of the Royal Society B: Biological Sciences 374, nr 1764 (3.12.2018): 20180017. http://dx.doi.org/10.1098/rstb.2018.0017.
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Widespread changes in water temperatures, salinity, alkalinity and pH have been documented in inland waters in North America, which influence ion exchange, weathering rates, chemical solubility and contaminant toxicity. Increasing major ion concentrations from pollution, human-accelerated weathering and saltwater intrusion contribute to multiple ecological stressors such as changing ionic strength and pH and mobilization of chemical mixtures resulting in the freshwater salinization syndrome (FSS). Here, we explore novel combinations of elements, which are transported together as chemical mixtures containing salts, nutrients and metals as a consequence of FSS. First, we show that base cation concentrations have increased in regions primarily in North America and Europe over 100 years. Second, we show interactions between specific conductance, pH, nitrate and metals using data from greater than 20 streams located in different regions of the USA. Finally, salinization experiments and routine monitoring demonstrate mobilization of chemical mixtures of cations, metals and nutrients in 10 streams draining the Washington, DC–Baltimore, MD metropolitan regions. Freshwater salinization mobilizes diverse chemical mixtures influencing drinking water quality, infrastructure corrosion, freshwater CO 2 concentrations and biodiversity. Most regulations currently target individual contaminants, but FSS requires managing mobilization of multiple chemical mixtures and interacting ecological stressors as consequences of freshwater salinization. This article is part of the theme issue ‘Salt in freshwaters: causes, ecological consequences and future prospects’.
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Gamlen-Greene, Roseanna, Jon S. Harding, David J. Hawke i Travis W. Horton. "Forest stream biota carbon : nitrogen ratios are unaffected by nutrient subsidies from breeding Westland petrels (Procellaria westlandica)". Marine and Freshwater Research 69, nr 10 (2018): 1508. http://dx.doi.org/10.1071/mf17301.
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Stable isotope studies have repeatedly shown marine nutrient incorporation from seabirds, anadromous fish and tidal wrack into terrestrial and freshwater ecosystems. However, little is known about the physiological consequences of marine-derived nutrient subsidies. Protein content and lipid storage are important physiologically, and the C:N ratio is a widely used proxy that reflects changes in these quantities. In this study we tested the response of C:N ratios in stream biota to the presence of marine-derived nutrients from Westland petrels, a forest breeding seabird. Samples of different stream invertebrate functional feeding groups, predatory freshwater fish, coarse particulate organic matter and riparian soil and vegetation came from four reference streams and four streams with a wide range of seabird densities. Samples were analysed for percentage C, percentage N and δ15N using isotope ratio mass spectrometry. The data were tested against petrel colony size, stream size and distance from colony to sampling site. Despite increased δ15N accompanying petrel presence (as reported previously), Westland petrels had no effect on stream biota C:N ratios, regardless of colony presence or absence or colony size. Despite the nutrients provided by petrels, we conclude that petrel N replaced rather than enhanced non-marine N in these stream ecosystems.
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Tippler, Carl, Ian A. Wright, Peter J. Davies i Alison Hanlon. "The influence of concrete on the geochemical qualities of urban streams". Marine and Freshwater Research 65, nr 11 (2014): 1009. http://dx.doi.org/10.1071/mf13164.
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The geochemical signature of freshwater streams can be used to determine the extent and nature of modification to stream water geochemistry due to urban development. This approach used the Gibbs (1970) diagram as a model for evaluation of changes to ionic composition linked to urban development. In this multi-year study, the geochemistry of 21 waterways in the Georges River catchment, Sydney, were monitored and compared with the level of urban development as measured by sub-catchment imperviousness and directly connected imperviousness. The results reflect a strong relationship between the intensity of sub-catchment urban development and stream geochemistry. All major geochemical attributes increased with escalating levels of urban development. The largest increase was for bicarbonate, which increased 18 times from a mean of 6.4 mg L–1 at non-urban streams to a mean of 118 mg L–1 at urban streams. Similarly, mean concentrations of calcium increased by 14 times (from 2 to 27.9 mg L–1). Mean salinity was enriched in the most urban streams, compared with non-urban streams, by more than 6 times. We attribute this, in part, to the influence of urban geology, notably concrete stormwater infrastructure. Changes in stream geochemistry due to urban development are an important element of the urban stream syndrome.
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Leitão, Rafael P., Érica P. Caramaschi i Jansen Zuanon. "Following food clouds: feeding association between a minute loricariid and a characidiin species in an Atlantic Forest stream, Southeastern Brazil". Neotropical Ichthyology 5, nr 3 (wrzesień 2007): 307–10. http://dx.doi.org/10.1590/s1679-62252007000300011.
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Following behavior is a widespread feeding tactic among marine fishes, but remains poorly documented for freshwater fishes. The present study describes such association between two freshwater species: the minute armored catfish Parotocinclus maculicauda and the South American darter Characidium sp. During underwater observations in an Atlantic Forest stream, we recorded Characidium sp. closely following P. maculicauda (<5cm), catching the particles dislodged by this catfish's grazing activity. The following behavior displayed by the darter is considered opportunistic and possibly favors the capture of preys associated to the periphyton. This study is one of the few records of nuclear-follower feeding association between freshwater fishes and the first one in Atlantic Forest streams.
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Riley, Lesilie, Mark Dybdahl i Robert Hall, Jr. "Grazing Effects of the New Zealand Mud Snail Across a Productivity Gradient in the Greater Yellowstone Ecosystem". UW National Parks Service Research Station Annual Reports 29 (1.01.2005): 96–104. http://dx.doi.org/10.13001/uwnpsrc.2005.3623.
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Accurately predicting the effects of introduced species on native commumtles and ecosystems is a challenge. Utilizing methods of food web ecology, we measured grazing effects of the invasive freshwater New Zealand mud snail, Potamopyrgus antipodarum, in streams within the Greater Yellowstone Ecosystem. Previous results indicate that P. antipodarum can significantly reduce algal standing stocks in less than one week, but it is not yet known if grazing effects vary across streams differing in benthic algae production. In this study, we measured the strength of P. antipodarum grazing on algal resources across six streams varying widely in ambient primary production. In field enclosure experiments within each stream, we estimated direct grazing effects of snails on algae by measuring chlorophyll a, gross primary production and chlorophyll a-specific primary production. In most streams, P. antipodarum decreased overall algal standing stocks, as measured by chlorophyll a, even though gross primary production was not affected. As a result, chlorophyll-a specific primary production increased in productive streams. Finally, standardized comparisons of P. antipodarum-algae interactions indicated that grazing effects were largest in the most productive streams. The overall impact of P. antipodarum on native stream communities will be greatest in the most productive streams if these assemblages are also capable of supporting dense P. antipodarum populations.
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Gonçalves, Cristina da Silva, i Francisco Manoel de Souza Braga. "Changes in ichthyofauna composition along a gradient from clearwaters to blackwaters in coastal streams of Atlantic forest (southeastern Brazil) in relation to environmental variables". Neotropical Ichthyology 10, nr 3 (wrzesień 2012): 675–84. http://dx.doi.org/10.1590/s1679-62252012000300022.
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The lack of knowledge of the freshwater ichthyofauna of coastal streams in the State of São Paulo (Brazil) is a cause of concern, as these streams are inserted in the Atlantic forest, a hotspot highly threatened. The aim of the present study is to investigate the freshwater ichthyofauna composition of clear and blackwater streams in a preservation area of Brazilian Atlantic forest. Fish samples were taken using electrofishing. A total of 20 species were registered, with Astyanax ribeirae, Hollandichthys multifasciatus, and Mimagoniates microlepis (Characiformes, Characidae) as the more representative. In general, the observed pattern of occurrence and distribution of fish species varied according to habitat characteristics, due to the longitudinal gradient in clearwaters, and among clearwaters and blackwaters. In clearwater streams, the headwater stretches had lower species diversity, while the opposite occurred in the middle and lower sites. These longitudinal variations of ichthyofauna were related with habitat characteristics (depth, stream flow, and bottom type) in which they were found, since the diversity of habitats was higher in headwaters and lower in downstream reaches (middle and lower sites). The physical and chemical variables of water do not seem to have influenced the distribution of species in clearwater streams, but the clear and blackwater fish composition was influenced mainly by pH concentration. Unlike the spatial differences, significant temporal differences were not registered in fish assemblages, probably due to the absence of a pronounced dry season in the studied region.
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Berejikian, Barry A., Lance A. Campbell i Megan E. Moore. "Large-scale freshwater habitat features influence the degree of anadromy in eight Hood Canal Oncorhynchus mykiss populations". Canadian Journal of Fisheries and Aquatic Sciences 70, nr 5 (maj 2013): 756–65. http://dx.doi.org/10.1139/cjfas-2012-0491.
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Juvenile Oncorhynchus mykiss maternity was determined from otolith strontium:calcium ratios to investigate the degree of anadromy in eight freshwater streams draining to a common fjord. The percentages of O. mykiss parr produced by anadromous females ranged from an annual average of 41.3% (Hamma Hamma River) to 100% (Dewatto River). The proportion of stream habitat available to resident O. mykiss upstream of barriers to anadromous migration explained a significant portion of the variability in maternal life history below barrier falls and was included in each of the five logistic regression models with the lowest AIC scores. Transitional hydrologic profiles, low mean annual temperatures and high mean annual stream flow, common to Olympic Peninsula streams, were each associated with greater proportions of offspring from resident females. Only 2 out of 234 parr from the lowland, rain-driven, low-flow streams of the Kitsap Peninsula were produced by resident females. Thus, large-scale habitat features, and primarily the presence or absence of resident populations above natural barriers to anadromous migration, appeared to shape the degree of anadromy among populations.
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French, G. L., J. Ling, K. L. Chow i K. K. Mark. "Occurrence of multiple antibiotic resistance and R-plasmids in gram-negative bacteria isolated from faecally contaminated fresh-water streams in Hong Kong". Epidemiology and Infection 98, nr 3 (czerwiec 1987): 285–99. http://dx.doi.org/10.1017/s095026880006204x.
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SUMMARYThe bacterial populations of six freshwater streams in populated areas of the Hong Kong New Territories were studied. There is considerable faecal contamination of these streams, with coliform counts as high as 105c.f.u./ml and the contaminating organisms show a high prevalence of antibiotic resistance and multiple resistance. With direct plating of water samples onto antibioticcontaining media, an average of 49% of the gram-negative bacteria were ampicillinresistant, 3% chloramphenicol-resistant and 1% gentamicin-resistant. At individual sites resistance to these three drugs was as high as 98%, 8% and 3% respectively. More than 70% of strains were resistant to two or more antibiotics, 29% to five or more and 2% to eight or more. A total of 98 patterns of antibiotic resistance were detected with no one pattern predominating. Twenty-eight gram-negative bacterial species were identified as stream contaminants.Escherichia coliwas the commonest bacterial species isolated and other frequent isolates wereEnterobactersp.,Klebsiellasp. andCitrobactersp., but no enteric pathogens were detected. The greatest prevalence of resistance and multiple resistance was associated with the heaviest contamination byE. coli.Analysis of selected stream isolates revealed multiple plasmid bands arranged in many different patterns, but multiple antibiotic resistances were shown to be commonly mediated by single transferable plasmids. Faecally-contaminated freshwater streams in Hong Kong may be reservoirs of antibiotic resistance plasmids for clinically-important bacteria.
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Bradford, Michael J., Ransom A. Myers i James R. Irvine. "Reference points for coho salmon (Oncorhynchus kisutch) harvest rates and escapement goals based on freshwater production". Canadian Journal of Fisheries and Aquatic Sciences 57, nr 4 (1.04.2000): 677–86. http://dx.doi.org/10.1139/f99-281.
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We describe a simple scheme for the management of coho salmon (Oncorhynchus kisutch) population aggregates that uses reference points derived from an empirical analysis of freshwater production data. We fit a rectilinear "hockey stick" model to 14 historical data sets of female spawner abundance and resulting smolt production and found that at low spawner abundance, the average productivity was about 85 smolts per female spawner. Variation in productivity among streams may be related to the quality of the stream habitat. We show how freshwater productivity can be combined with forecasts of marine survival to provide a limit reference point harvest rate. Our method will permit harvest rates to track changes in ocean productivity. We also used the historical data to estimate that, on average, a density of 19 female spawners·km-1 is required to fully seed freshwater habitats with juveniles. However, there was considerable variation among the streams that might limit the utility of this measure as a reference point. Uncertainty in the forecasts of marine survival and other parameters needs to be incorporated into our scheme before it can be considered a precautionary approach.
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Ekinadose Orose, Edafe Odioko i Okechukwu Kenneth Wokeh. "Catalogue of Some Saltwater and Freshwater Fish Species of the Niger Delta Region of Nigeria". World Journal of Advanced Research and Reviews 9, nr 3 (30.03.2021): 056–84. http://dx.doi.org/10.30574/wjarr.2021.9.3.0075.
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The study was done to review some saltwater and freshwater fish species in the Niger Delta region of Nigeria. The Niger Delta is one of the most prominent regions in Nigeria, endowed with several water bodies that are distributed as freshwater like rivers, lakes, streams and creeks. These freshwater ecosystems in the region, are abundantly endowed with fish species such as Clarias gariepinus, Pila ovate, Labeo coubie, Synodontis budgetti and Synodontis eupterus. Apart from the freshwaters, the region also has vast marine ecosystem with abundance of fish species such as Elops lacerta, Mugil cephalus, Thais coronata, Periophthalmus papilio, Tympanotonus fuscatus, and Sardinella maderensis. Unfortunately, many of these fish species are endangered due to constant pollution in the Niger delta regional coastal environment. As a result, it is important to document some available freshwater and marine water fish species which will serve as a reference material for both academics and research institutions, should any of the fish species go into extinction.
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Li, Ke, Cory O. Brant, Mar Huertas, Edward J. Hessler, Gellert Mezei, Anne M. Scott, Thomas R. Hoye i Weiming Li. "Fatty-acid derivative acts as a sea lamprey migratory pheromone". Proceedings of the National Academy of Sciences 115, nr 34 (30.07.2018): 8603–8. http://dx.doi.org/10.1073/pnas.1803169115.
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Olfactory cues provide critical information for spatial orientation of fish, especially in the context of anadromous migrations. Born in freshwater, juveniles of anadromous fish descend to the ocean where they grow into adults before migrating back into freshwater to spawn. The reproductive migrants, therefore, are under selective pressures to locate streams optimal for offspring survival. Many anadromous fish use olfactory cues to orient toward suitable streams. However, no behaviorally active compounds have been identified as migratory cues. Extensive studies have shown that the migratory adult sea lampreys (Petromyzon marinus), a jawless fish, track a pheromone emitted by their stream-dwelling larvae, and, consequently, enter streams with abundant larvae. We fractionated extracts of larval sea lamprey washings with guidance from a bioassay that measures in-stream migratory behaviors of adults and identified four dihydroxylated tetrahydrofuran fatty acids, of which (+)-(2S,3S,5R)-tetrahydro-3-hydroxy-5-[(1R)-1-hydroxyhexyl]-2-furanoctanoic acid was shown as a migratory pheromone. The chemical structure was elucidated by spectroscopies and confirmed by chemical synthesis and X-ray crystallography. The four fatty acids were isomer-specific and enantiomer-specific in their olfactory and behavioral activities. A synthetic copy of the identified pheromone was a potent stimulant of the adult olfactory epithelium, and, at 5 × 10−13 M, replicated the extracts of larval washings in biasing adults into a tributary stream. Our results reveal a pheromone that bridges two distinct life stages and guides orientation over a large space that spans two different habitats. The identified molecule may be useful for control of the sea lamprey.
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Wood, C. C. "Predation of Juvenile Pacific Salmon by the Common Merganser (Mergus merganser) on Eastern Vancouver Island. II: Predation of Stream-Resident Juvenile Salmon by Merganser Broods". Canadian Journal of Fisheries and Aquatic Sciences 44, nr 5 (1.05.1987): 950–59. http://dx.doi.org/10.1139/f87-113.
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Predation of stream-resident juvenile salmonids by broods of the common merganser (Mergus merganser) was investigated in three streams on eastern Vancouver Island from 1980 to 1982. Daily fish consumption by merganser ducklings was estimated to range from 80% of body weight for ducklings at 10 d of age to 40% of body weight for those at 40 d of age. Merganser ducklings were never observed to eat juvenile salmonids on tidal waters, but did eat them on the freshwater reaches of streams studied. Typically, broods inhabited only the freshwater reaches of their natal stream while young, but spent progressively more time foraging on tidal waters as they grew older. The biomass of broods (and hence potential consumption) on fresh water was estimated by reconstructing the history of individual broods from census data. These results suggest that merganser broods consumed on the order of 82 000–131 000 coho salmon (Oncorhynchus kisutch) fry in the Big Qualicum River between June 10 and August 25. This is equivalent to 24–65% of the observed wild smolt production from this system, assuming that these fry would otherwise have survived as well as uneaten fry.
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Tsuboi, Jun-ichi, Kentaro Morita, Thomas Klefoth, Shinsuke Endou i Robert Arlinghaus. "Behaviour-mediated alteration of positively size-dependent vulnerability to angling in response to historical fishing pressure in a freshwater salmonid". Canadian Journal of Fisheries and Aquatic Sciences 73, nr 3 (marzec 2016): 461–68. http://dx.doi.org/10.1139/cjfas-2014-0571.
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Positively size-selective vulnerability to fishing is well established in recreational fisheries. Size-selective harvesting can either induce an indirect selection response of behavioural traits that are correlated with size or exert direct selection pressures on behaviours that contribute to vulnerability. In addition, learning to avoid future capture may always happen. Behavioural change caused by fishing may in turn affect the size-selective properties of angling. To test this prediction, field experiments with amago salmon (Oncorhynchus masou ishikawae) were conducted. We demonstrated that, as expected, large fish were more vulnerable than smaller individuals in a low fishing pressure (LP) stream and that positively size-selective angling was not (or no longer) present in a high fishing pressure (HP) stream. Moreover, fish in the HP stream were by far less vulnerable to angling with natural bait than fishes in the LP stream. Laboratory studies showed that offspring from HP streams were intrinsically shyer than offspring collected from LP streams. We propose that the increased timidity of individuals inhibiting HP streams disrupted the generally positive relationship among salmon body size and its vulnerability to angling. Fisheries-induced timidity in response to high exploitation rates reduces catchability, affects the size-selective properties of angling, reduces the value of fishery-dependent stock assessments, and potentially affects trophic interactions.
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Timm, Henn, i Marina Haldna. "Do abundance and percentage of dipteran larvae and Oligochaeta indicate low water quality in streams and lake littoral?" Oceanological and Hydrobiological Studies 48, nr 4 (18.12.2019): 415–29. http://dx.doi.org/10.2478/ohs-2019-0036.
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Abstract The presence of chironomids and/or oligochaetes is generally considered to be an indication of poor status of freshwater. Non-chironomid dipterans show unclear trends. The abundance and percentage of these groups are rarely used as potential indicators. We attempted to determine whether these metrics reveal freshwater quality in lowland streams and lake littoral (Northern Europe, Baltic ecoregion, Estonia). The water quality was assessed based either on the water itself or on macroinvertebrates, fish, macrophytes, phytobenthos (in streams only) and/or phytoplankton (in lakes only). As expected, the high abundance and high percentage of chironomids and ceratopogonids indicated low quality of water in lakes. The high percentage of chironomids indicated low water quality also in streams. The high percentage of oligochaetes indicated low water quality in lakes. However, their high abundance (but not the percentage) was unexpectedly a symptom of high water quality in streams and to a lesser extent in lakes. In these cases, oligochaetes were represented by rheophilic, rather than saprophilic species. The abundance of simuliids (but not the percentage) and the richness of dipteran families indicated high water quality in streams. We suggest that the obtained results will allow better use of the indicative potential of freshwater macroinvertebrates.
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Krzewicka, Beata, Jerzy Smykla, Joanna Galas i Lucyna Śliwa. "Freshwater lichens and habitat zonation of mountain streams". Limnologica 63 (marzec 2017): 1–10. http://dx.doi.org/10.1016/j.limno.2016.12.002.
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Hoess, Rebecca, Konstantina A. Generali, Johannes Kuhn i Juergen Geist. "Impact of Fish Ponds on Stream Hydrology and Temperature Regime in the Context of Freshwater Pearl Mussel Conservation". Water 14, nr 16 (12.08.2022): 2490. http://dx.doi.org/10.3390/w14162490.
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Conservation of endangered, cold-stenothermic species, such as the freshwater pearl mussel (FPM) and its salmonid host fish, are particularly challenging in headwater streams as their last refuge areas. Understanding the impact of anthropogenic catchment features such as fish ponds on the hydrology and the temperature regime of such streams is, therefore, important. In this study, runoff in a FPM catchment with more than 150 small ponds was simulated using SWAT and compared to a scenario without ponds. Additionally, water temperature was monitored hourly along three steams over 2.5 years, at sites upstream and downstream of the inflow of pond outlet channels. Temperature metrics were related to land use within a 180 m corridor along the streams. Peak flows were reduced by 1.5% with ponds, while low flows were increased by 4.5%. In summer, temperature in pond effluents was higher than in the receiving stream, depending on the proximity of the inflow points. Discharge from close-by ponds increased summer stream temperature directly downstream of the inflow by up to 5.5 °C. These increased temperatures were partly compensated by groundwater contribution in forested areas. In contrast, stream temperature significantly further increased along stretches flowing through open land, persisting independently of pond inflows. We suggest incorporating this knowledge on pond- and land use-dependent effects on stream temperature regimes into the conservation management of FPM and other cold-stenothermic species, as well as into climate change mitigation strategies targeting an increased resilience against temperature extremes.
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Kalinowski, Steven T., Michael H. Meeuwig, Shawn R. Narum i Mark L. Taper. "Stream trees: a statistical method for mapping genetic differences between populations of freshwater organisms to the sections of streams that connect them". Canadian Journal of Fisheries and Aquatic Sciences 65, nr 12 (grudzień 2008): 2752–60. http://dx.doi.org/10.1139/f08-171.
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Statistical approaches for studying the spatial distribution of genetic diversity that assume that organisms move through a two-dimensional landscape are not well suited to study populations of freshwater fish. We present a new statistical method for mapping genetic differences among populations of freshwater fish to the sections of streams that connect them. The method is useful for freshwater species that can only disperse through stream corridors and for other species that live in habitats for which there is one, and only one, corridor connecting each pair of populations (e.g., alpine organisms confined to ridge tops). The model is a simple extension of the least-squares method for constructing evolutionary trees. In this model, the genetic distances between populations are modeled as a sum of genetic distances mapped onto landscape features (e.g., stream sections). Analysis of simulated data shows that the method produces useful results with realistic amounts of data. The model was fit to empirical microsatellite data from four metapopulations of freshwater fish and showed an excellent fit in three out of four cases. Software to perform the necessary calculations is available from the authors at www.montana.edu/kalinowski .
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Chaloner, Dominic T., Kristine M. Martin, Mark S. Wipfli, Peggy H. Ostrom i Gary A. Lamberti. "Marine carbon and nitrogen in southeastern Alaska stream food webs: evidence from artificial and natural streams". Canadian Journal of Fisheries and Aquatic Sciences 59, nr 8 (1.08.2002): 1257–65. http://dx.doi.org/10.1139/f02-084.
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Incorporation of marine-derived nutrients (MDN) into freshwater food webs of southeastern Alaska was studied by measuring the natural abundance of nitrogen and carbon stable isotopes in biota from artificial and natural streams. Biofilm, aquatic macroinvertebrates (detritivores, shredders, and predators), and fish (coho salmon, Oncorhynchus kisutch, and cutthroat trout, Oncorhynchus clarki) were sampled from streams in which Pacific salmon (Oncorhynchus spp.) carcasses had been artificially placed or were present naturally. In the presence of carcasses, all trophic levels incorporated marine-derived nitrogen (range, 2273% of total N) and carbon (range, 752% of total C). In general, chironomid midges assimilated more marine-derived nitrogen and carbon than did other consumers. The assimilation of MDN by aquatic organisms and subsequent isotopic enrichment (56 for 15N, 34 for 13C) were similar in experimentally and naturally carcass-enriched streams. For specific taxa, however, percent assimilation for marine nitrogen and carbon were often dissimilar, possibly because of fractionation or transfer inefficiencies. These results suggest that pathways of MDN incorporation into stream food webs include both consumption of salmon material by macroinvertebrates and fish and uptake of mineralized MDN by biofilm. Incorporation of MDN into multiple trophic levels demonstrates the ecological significance of annual returns of anadromous fishes for sustaining the productivity of freshwater food webs.
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Swain, Noel R., Morgan D. Hocking, Jennifer N. Harding i John D. Reynolds. "Effects of salmon on the diet and condition of stream-resident sculpins". Canadian Journal of Fisheries and Aquatic Sciences 71, nr 4 (kwiecień 2014): 521–32. http://dx.doi.org/10.1139/cjfas-2013-0159.
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Pacific salmon (Oncorhynchus spp.) can subsidize freshwater food webs with marine-derived nutrients from their eggs, juveniles, and carcasses. However, trophic interactions between spawning salmon and freshwater fish across natural gradients in salmon subsidies remain unclear. We tested how salmon affected the diets and condition of two dominant freshwater consumers — prickly and coastrange sculpins (Cottus asper and Cottus aleuticus, respectively) — across a wide gradient of pink salmon (Oncorhynchus gorbuscha) and chum salmon (Oncorhynchus keta) biomass from 33 streams in the Great Bear Rainforest of British Columbia, Canada. Sculpin diets shifted from invertebrates and juvenile salmonids to salmon eggs when salmon arrived in autumn, with salmon-derived nutrient contributions to diets and sculpin condition increasing with increasing biomass of spawning salmon among streams. Season, habitat, and individual sculpin body size and species also mediated the effects of salmon on sculpin diet as inferred from their carbon and nitrogen stable isotope signatures. This study shows the timing and pathways by which spawning salmon influence the diets and condition of freshwater consumers, and some of the individual and environmental factors that can regulate uptake of salmon nutrients in streams, thus informing ecosystem-based management.
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Little, Chelsea J., i Florian Altermatt. "Do priority effects outweigh environmental filtering in a guild of dominant freshwater macroinvertebrates?" Proceedings of the Royal Society B: Biological Sciences 285, nr 1876 (11.04.2018): 20180205. http://dx.doi.org/10.1098/rspb.2018.0205.
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Abiotic conditions have long been considered essential in structuring freshwater macroinvertebrate communities. Ecological drift, dispersal and biotic interactions also structure communities, and although these mechanisms are more difficult to detect, they may be of equal importance in natural communities. Here, we hypothesized that in 10 naturally replicated headwater streams in eastern Switzerland, locally dominant amphipod species would be associated with differences in environmental conditions. We conducted repeated surveys of amphipods and used a hierarchical joint species distribution model to assess the influence of different drivers on species co-occurrences. The species had unique environmental requirements, but a distinct spatial structure in their distributions was unrelated to habitat. Species co-occurred much less frequently than predicted by the model, which was surprising because laboratory and field evidence suggests they are capable of coexisting in equal densities. We suggest that niche preemption may limit their distribution and that a blocking effect related to the specific linear configuration of streams determines which species colonizes and dominates a given stream catchment, thus suggesting a new solution a long-standing conundrum in freshwater ecology.
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Rosati, Ted C., Jeffrey R. Johansen i Miles M. Coburn. "Cyprinid fishes as samplers of benthic diatom communities in freshwater streams of varying water quality". Canadian Journal of Fisheries and Aquatic Sciences 60, nr 2 (1.02.2003): 117–25. http://dx.doi.org/10.1139/f03-004.
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The diatom composition of natural substrates in streams of different water qualities was compared among samples collected by researchers and samples collected from the intestine contents of three species of Cyprinid fishes: Campostoma anomalum, Pimephales notatus, and Semotilus atromaculatus. Campostoma and Pimephales were found to be robust samplers that efficiently collected diverse, representative diatom samples. Semotilus were adequate diatom samplers but collected the most diverse samples. In no instance were water-quality indices calculated from Pimephales samples significantly different from human-collected composite samples, whereas Campostoma and Semotilus samples diverged slightly from human-collected composite samples. Internal similarities of fish-collected samples were not significantly higher than those of human-collected samples, indicating that the fish were indiscriminately foraging on diatoms. Furthermore, samples clustered primarily by stream, indicating that fish-collected samples of diatoms were as representative of the stream as those collected by human researchers. By all standards measured in this study, these three fish species sample the benthic diatom community of mid-order streams with a facility equal to that of trained ecologists.
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Ishikawa, Asano, Yoel E. Stuart, Daniel I. Bolnick i Jun Kitano. "Copy number variation of a fatty acid desaturase gene Fads2 associated with ecological divergence in freshwater stickleback populations". Biology Letters 17, nr 8 (sierpień 2021): 20210204. http://dx.doi.org/10.1098/rsbl.2021.0204.
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Fitness of aquatic animals can be limited by the scarcity of nutrients such as long-chain polyunsaturated fatty acids, especially docosahexaenoic acid (DHA). DHA availability from diet varies among aquatic habitats, imposing different selective pressures on resident animals to optimize DHA acquisition and synthesis. For example, DHA is generally poor in freshwater ecosystems compared to marine ecosystems. Our previous work revealed that, relative to marine fishes, several freshwater fishes evolved higher copy numbers of the fatty acid desaturase2 ( Fads2 ) gene, which encodes essential enzymes for DHA biosynthesis, likely compensating for the limited availability of DHA in freshwater. Here, we demonstrate that Fads2 copy number also varies between freshwater sticklebacks inhabiting lakes and streams with stream fish having higher Fads2 copy number. Additionally, populations with benthic-like morphology possessed higher Fads2 copy number than those with planktivore-like morphology. This may be because benthic-like fish mainly feed on DHA-deficient prey such as macroinvertebrates whereas planktivore-like fish forage more regularly on DHA-rich prey, like copepods. Our results suggest that Fads2 copy number variation arises from ecological divergence not only between organisms exploiting marine and freshwater habitats but also between freshwater organisms exploiting divergent resources.
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Wood, C. C. "Dispersion of common merganser (Mergus merganser) breeding pairs in relation to the availability of juvenile Pacific salmon in Vancouver Island streams". Canadian Journal of Zoology 64, nr 3 (1.03.1986): 756–65. http://dx.doi.org/10.1139/z86-112.
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Common merganser (Mergus merganser) breeding pairs and broods were censused on eight coastal streams on Vancouver Island to evaluate the relative importance of the number of potential breeding pairs, stream size, and the availability of juvenile Pacific salmon in limiting merganser breeding density. The number of potential breeding pairs did not limit nesting density on at least one stream where juvenile salmon populations were enhanced by a hatchery and spawning channel. At distances > 1 km above tidal influence, breeding pairs were evenly dispersed along the streams during the peak egg-laying and incubation period at maximum densities of 0.4–1.4 pairs/km. Maximum breeding pair counts were higher and more variable among streams on the lower kilometer of freshwater (1–9 pairs) and on tidal waters near the stream outlets (4–9 pairs). Stream size accounted for only a part of the variation in breeding pair counts. The estimated number of broods produced on each stream was highly correlated (r = 0.95) with both drainage area and juvenile salmon production, including production from hatcheries. Possible mechanisms relating the dispersion of breeding pairs to the availability of juvenile salmon are discussed. A "food assessment" hypothesis, whereby breeding pairs choose a nesting stream on the basis of prey availability during the nesting season, could not be rejected on the basis of predictions about hatching dates and duckling survival. This hypothesis has serious implications for mortality of wild salmonids in hatchery-enhanced streams.
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Lowe, Winsor H., Leah K. Swartz, Brett R. Addis i Gene E. Likens. "Hydrologic variability contributes to reduced survival through metamorphosis in a stream salamander". Proceedings of the National Academy of Sciences 116, nr 39 (5.09.2019): 19563–70. http://dx.doi.org/10.1073/pnas.1908057116.
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Changes in the amount, intensity, and timing of precipitation are increasing hydrologic variability in many regions, but we have little understanding of how these changes are affecting freshwater species. Stream-breeding amphibians—a diverse group in North America—may be particularly sensitive to hydrologic variability during aquatic larval and metamorphic stages. Here, we tested the prediction that hydrologic variability in streams decreases survival through metamorphosis in the salamander Gyrinophilus porphyriticus, reducing recruitment to the adult stage. Using a 20-y dataset from Merrill Brook, a stream in northern New Hampshire, we show that abundance of G. porphyriticus adults has declined by ∼50% since 1999, but there has been no trend in larval abundance. We then tested whether hydrologic variability during summers influences survival through metamorphosis, using capture–mark–recapture data from Merrill Brook (1999 to 2004) and from 4 streams in the Hubbard Brook Experimental Forest (2012 to 2014), also in New Hampshire. At both sites, survival through metamorphosis declined with increasing variability of stream discharge. These results suggest that hydrologic variability reduces the demographic resilience and adaptive capacity of G. porphyriticus populations by decreasing recruitment of breeding adults. They also provide insight on how increasing hydrologic variability is affecting freshwater species, and on the broader effects of environmental variability on species with vulnerable metamorphic stages.
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Chamier, Anne-Carole. "Microbial degradation of leaf litter in freshwater streams: effect of low pH – abstract". Proceedings of the Royal Society of Edinburgh. Section B. Biological Sciences 94 (1988): 107–8. http://dx.doi.org/10.1017/s0269727000007181.
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Many freshwater streams are predominantly heterotrophic, the energy source for all trophic levels of the biota being derived from allochthonous plant litter that is degraded by saprotrophic micro-organisms. Leaves falling into streams have most of their soluble constituents leached out within twenty-four hours of submersion. Few of the resident terrestrial saprotrophs survive in the aquatic environment and the leaves are rapidly colonised by freshwater fungi, particularly aquatic hyphomycetes (Chamier & Dixon 1982a; Chamier et al. 1984). These fungi produce all the enzymes required to degrade the structural polysaccharides of leaf cell walls and those of resident terrestrial fungi. Some species can degrade lignified tissue (Chamier & Dixon 1982b; Chamier 1985). Little is known of the enzymic capabilities of freshwater bacteria.
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Calvão, Lenize Batista, Paulo De Marco Júnior i Joana Darc Batista. "Odonata (Insecta) from Nova Xavantina, Mato Grosso, Central Brazil: Information on species distribution and new records". Check List 10, nr 2 (1.05.2014): 299. http://dx.doi.org/10.15560/10.2.299.
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Odonates are found in all freshwater environments, and are specially species rich in tropical freshwater ecosystems. Currently about 800 odonate species are known to Brazil, but only 29% of the Brazil territory have been surveyed for this group. Here we provide a species list with information on distribution and new records for Odonata in nine streams in Nova Xavantina, Mato Grosso, Central Brazil. We used the scan procedure with a fixed area for three days in each stream between 10:00 and 14:00h. We collected 1038 dragonfly specimens belonging to 67 species, which represents 8% of the known Brazil odonate fauna. Additionally, five new records for the study area are presented.
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Schulz, Claus-Jürgen, i Miguel Cañedo-Argüelles. "Lost in translation: the German literature on freshwater salinization". Philosophical Transactions of the Royal Society B: Biological Sciences 374, nr 1764 (3.12.2018): 20180007. http://dx.doi.org/10.1098/rstb.2018.0007.
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Human activities have globally increased and altered the ion concentration of freshwater ecosystems. The proliferation of potash mines in Germany (especially intense in the early 1900s) constitutes a good example of it. The effluents and runoff coming from potash mines led to extreme salt concentrations (e.g. 72 g l–1of total salt content, approx. 149 mS cm–1) in surrounding rivers and streams, causing ecosystem degradation (e.g. massive algal blooms and fish kills). This promoted scientific research that was mostly published in German, thereby being neglected by the wide scientific community. Here, the findings of the German literature on freshwater salinization are discussed in the light of current knowledge. German studies revealed that at similar ion concentrations potassium (K+) can be the most toxic ion to freshwater organisms, whereas calcium (Ca2+) could have a toxicity ameliorating effect. Also, they showed that salinization could lead to biodiversity loss, major shifts in the composition of aquatic communities (e.g. dominance of salt-tolerant algae, proliferation of invasive species) and alter organic matter processing. The biological degradation caused by freshwater salinization related to potash mining has important management implications, e.g. it could prevent many European rivers and streams from reaching the good ecological status demanded by the Water Framework Directive. Within this context, German publications show several examples of salinity thresholds and biological indices that could be useful to monitor and regulate salinization (i.e. developing legally enforced salinity and ion-specific standards). They also provide potential management techniques (i.e. brine collection and disposal) and some estimates of the economic costs of freshwater salinization. Overall, the German literature on freshwater salinization provides internationally relevant information that has rarely been cited by the English literature. We suggest that the global editorial and scientific community should take action to make important findings published in non-English literature more widely available.This article is part of the theme issue ‘Salt in freshwaters: causes, ecological consequences and future prospects’.
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Mushi, Douglas. "Clostridium perfringens identifies source of pollution and reference streams in a tropical highland environment". Journal of Water and Health 16, nr 4 (11.06.2018): 501–7. http://dx.doi.org/10.2166/wh.2018.192.
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Abstract Clostridium perfringens was analysed in soils from a tropical highland catchment and corresponding headwater streams at baseflow condition in order to understand the contribution of soils to the microbiological quality of stream water and the feasibility of using these streams as surrogate for negative control (reference streams). The concentrations of C. perfringens depended on the sample matrix. C. perfringens concentrations were significantly higher in the catchment soil than in the stream water (P < 0.05, n = 20). In addition, C. perfringens concentrations in the catchment soil remarkably predicted C. perfringens concentrations in the stream water (i.e., 82% of variations in C. perfringens concentrations in water were predicted by C. perfringens concentrations in soil; P < 0.05, n = 20). This suggests that the catchment soils contributed C. perfringens to the stream water. Despite the observed contamination, the concentrations of C. perfringens (geometric mean of 32 cfu/100 cm3) in the stream water was below the recommended safe level for tropical freshwater systems and extremely lower than that detected in anthropogenically influenced rivers. This concentration was defined as an acceptable level of disturbance, and a reference concentration that can serve as surrogate for negative control in the studied tropical environment.
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Soo, Chen, Hairul Mahsol, Leonardo Jainih, Arman Fikri, Cheng Chen i Nur Kamal. "Fish Biodiversity and Water Quality of Tropical Forest Streams Adjacent to the Western Boundary of Kinabalu Park, Sabah". Journal of Tropical Life Science 12, nr 2 (17.05.2022): 261–68. http://dx.doi.org/10.11594/jtls.12.02.12.
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Modification and degradation of habitats outside the boundaries of a national parkmay result in the park's integrity being compromised. Thus, the present study aims todocument variation in freshwater fish and water quality of tropical forest streams adjacent to the western boundary of Kinabalu Park, Sabah. Concurrently, fish samplesand environmental parameters were collected at six stations covering a total streamline length of 10 km. The three most abundant species were Tor tambra (34.4%), Barbodes sealei (19.5%), and Lobocheilos ovalis (12.4%). Tor tambra exhibited a negative allometric growth pattern (coefficient < 3) and was in poor to fair condition (0.8< Fulton’s condition factor < 1.2). The highest fish abundance was found in downstream stations with species addition. Metrics of diversity, such as Shannon's diversityindex and the Margalef index of species richness, decreased as elevation increasedfrom 100 to 600 metres above sea level. The water quality of the forest streams isgood, classified as Class I and/or Class II by Malaysia's National Water Quality Standards, except for ammoniacal nitrogen at station 6, which was classified as Class III.Higher turbidity, orthophosphate, and ammoniacal-nitrogen values were found nearthe Podos village. In conclusion, the altitudinal gradient of fish biodiversity was observed in the forest streams near Kinabalu Park. Regular water quality monitoring ofthe downstream river is necessary, as indicated by the potential domestic impacts onthe river.Keywords: Biodiversity, Elevation, Freshwater fish, Forest stream, Kinabalu Park
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Wipfli, Mark S., John P. Hudson, Dominic T. Chaloner i John P. Caouette. "Influence of salmon spawner densities on stream productivity in Southeast Alaska". Canadian Journal of Fisheries and Aquatic Sciences 56, nr 9 (1.09.1999): 1600–1611. http://dx.doi.org/10.1139/f99-087.
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We conducted this study to determine the relationship between salmon spawner abundance and stream biofilm and benthic macroinvertebrate abundance in Southeast Alaska. Experiments took place in outdoor artificial and natural streams. Six pink salmon (Oncorhynchus gorbuscha) carcass treatments (0.00, 1.45, 2.90, 4.35, 5.80, and 7.25 kg wet mass) placed in artificial channels were subsampled repeatedly for biofilm ash-free dry mass (AFDM), chlorophyll a, and macroinvertebrates. In a small (nonanadromous) forest stream, we sampled benthos throughout a 66-m reach 17 days after distributing 60 carcasses along the lower half of that reach. All response variables significantly increased in response to carcass additions in both artificial and natural streams. Chlorophyll a continued to increase across all loading rates, while AFDM and total macroinvertebrate densities showed no further response to loading beyond the first treatment (1.45 kg) in artificial streams. In the natural stream, AFDM and chironomid densities continued increasing across loading levels. These results indicated that increased spawner densities increased lower trophic level abundance until a trophic capacity was reached. Salmon escapement goals should consider food web effects, especially on trophic levels that support juvenile salmonids, that ultimately affect freshwater salmon production.
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Price, David J., i Wesley J. Birge. "Effectiveness of stream restoration following highway reconstruction projects on two freshwater streams in Kentucky". Ecological Engineering 25, nr 1 (lipiec 2005): 73–84. http://dx.doi.org/10.1016/j.ecoleng.2005.03.002.
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Pizarro, Haydée, Irina Izaguirre i Guillermo Tell. "Epilithic algae from a freshwater stream at Hope Bay, Antarctica". Antarctic Science 8, nr 2 (czerwiec 1996): 161–67. http://dx.doi.org/10.1017/s0954102096000235.
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Temporal and spatial variations of the epilithic phycoflora were studied in one of the largest streams at Hope Bay (Antarctic Peninsula) during the summer of 1992/93. A complete floristic inventory was made, and the relative frequencies of each algal taxon were estimated. Periphytic cumulative chlorophyll a was measured by means of artificial substrata. The stream was a typical maritime Antarctic lotic ecosystem, with evident signs of enrichment by sea-birds. Variability in discharge strongly affected the water chemistry, with the high water level periods characterized by the lowest conductivities and dissolved reactive phosphorus concentrations. Epilithic algal communities predominantly consisted of algal mats or filamentous and foliose forms of Prasiola crispa. Other dominant species were Leptolyngbya fragilis, Hydrurus foetidus, Chrysococcus cf. rufescens and Phaeogloea mucosa. Whereas P. crispa appeared more frequently near to the origin of the stream in Boeckella Lake, Chrysophyceae were better developed towards the mouth.
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Broady, Paul A. "The distribution of Prasiola calophylla (Carmich.) Menegh. (Chlorophyta) in Antarctic freshwater and terrestrial habitats". Antarctic Science 1, nr 2 (czerwiec 1989): 109–18. http://dx.doi.org/10.1017/s0954102089000179.
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Specimens of Prasiola collected from habitats not experiencing nutrient enrichment from birds are considered to be P. calophylla. The alga has three distinct growth forms; uniseriate filaments, narrow ribbons and expanded sheets. Reproduction is by aplanospores and fragmentation of the thallus. The known Antarctic distribution is disjunct with only two records outside Victoria Land. However, it is widespread in the latter region. The alga is absent from areas where there are high salt concentrations in waters and soils. Elsewhere it is common in streams and on water-flushed ground as well as occurring on terminal ice-faces of glaciers and as chasmoendolithic growths. Ribbons are found mostly on the lower surfaces of stones, and uniseriate filaments on the exposed surfaces of the stream beds of seasonal melt streams. Expanded sheets occur in less vigorous water flows. There is a need for further culture and field studies in order to understand the factors which control morphological development and distribution patterns.
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Hachułka, Mariusz. "Freshwater lichens on submerged stones and alder roots in the Polish lowlands". Acta Mycologica 46, nr 2 (23.12.2013): 233–44. http://dx.doi.org/10.5586/am.2011.016.
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The article presents the results of the studies of lichens in streams and spring areas of the escarpment zone of Wzniesienia Łódzkie Heights in Central Poland. The boulders, stones and roots of Alnus glutinosa, situated in 3 inundated zones in the streams: submerged zone, fluvial mesic zone and fluvial xeric zone, were examined in the streams. The studies have shown 23 species connected with these streams. Six species of freshwater lichens: <em>Verrucaria aquatilis, V. hydrela, Hydropunctaria rheitrophila, V. margacea, V. praetermissa</em> and <em>V. madida</em>, occupied stones in 3 different zones. <em>Verrucaria aquatilis</em> and <em>Hydropunctaria rheitrophila</em> colonized also secondary substrates – the bark of alder roots incrusted with sand grains and silt.
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Silva Camargo, Paulo Ricardo da, Luiz Felipe Godinho Barreiros, Newton Pimentel Ulhôa Barbosa, Antônio Valadão Cardoso, Paulo Santos Assis i Afonso Pelli. "Golden mussel geographic distribution paradox: how can stream theories explain?" International Journal of Hydrology 6, nr 2 (18.04.2022): 73–77. http://dx.doi.org/10.15406/ijh.2022.06.00304.
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Aquatic ecosystems have biological, social, and economic importance. Between the 1980s and 2000s, a few theoretical concepts emerged that attempt to provide a better understanding of the function and dynamics of freshwater ecosystems, including biotic and abiotic variables. The rationale for our research was based on observations of the distribution and abundance of an exotic bivalve mollusc, the golden mussel Limnoperna fortunei (Dunker, 1857). The species has been recorded from several river basins, but only occurs in large water bodies and fails to reach first-order streams. This study provides an overview of the main stream ecology concepts developed to explain the dynamics of lotic ecosystems in an attempt to solve this paradox. The river continuum concept was the first of many in river ecology. These theoretical concepts are not mutually exclusive, but interdependent. It is expected the main reasons for the non-occurrence of L. fortunei in small streams are twofold: fluctuations in physical and hydrologic conditions in small streams, generating instability, and reduced availability of plankton in first- and second-order streams.
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Akindele, Emmanuel O., i Godwin O. Olutona. "Water Physicochemistry and Zooplankton Fauna of Aiba Reservoir Headwater Streams, Iwo, Nigeria". Journal of Ecosystems 2014 (19.11.2014): 1–11. http://dx.doi.org/10.1155/2014/105405.
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The physicochemical water condition and zooplankton fauna of the two main inflows of Aiba Reservoir were assessed over an annual hydrological cycle (May 2013–March 2014). The concentrations of total solids (TS) and total suspended solids (TSS) in the two streams were unusually higher in the dry season for typical inland waters of Nigeria and showed a decrease from the upper reaches towards the lower reaches (reservoir’s inlet). Dissolved oxygen, NO3-, and PO43- recorded their highest concentrations at the reservoir’s inlet. A total of 37 species of zooplankton were recorded in the study, comprising 5 species of Protozoa, 14 species of Rotifera, 10 species of Copepoda, 4 species of Ostracoda, and 4 species of Insecta. Aiba stream recorded higher number of zooplankton species and abundance than Onikan stream. While number of zooplankton species and abundance showed an increase from the upper reaches to the lower reaches of both streams, species diversity and equitability generally showed a decrease. Correlation and regression analysis suggests that the concentration of TS and TSS played a major role in determining the zooplankton community structure of the streams. PO43- concentrations as well as the community structures of zooplankton faunas of the two streams were indicative of a polluted freshwater system with unstable habitat structure.
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Krzewicka, Beata, Natalia Matura, Edyta Adamska i Piotr Osyczka. "Species composition of freshwater lichens in temperate mountain streams". Preslia 92, nr 3 (2020): 235–54. http://dx.doi.org/10.23855/preslia.2020.235.
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Tikhonenkov, D. V., i Yu A. Mazei. "Heterotrophic flagellate biodiversity and community structure in freshwater streams". Inland Water Biology 1, nr 2 (kwiecień 2008): 129–33. http://dx.doi.org/10.1134/s1995082908020041.
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