Effects of experimentally enhanced flows on fishes of a small Texas (U.S.A.) stream: assessing the impact of interbasin transfer

1. Completion of a large interbasin water transfer system in northern Texas (U.S.A.) provided the opportunity to test the effects of pre-planned, experimental increases (≈×30) in flow on the fish fauna of a small, low-gradient, natural stream that was included as part of the conveyance system. Water from Lake Texoma (Red River basin) was pumped via a 16-km pipeline to the headwaters of Sister Grove Creek (Trinity River basin), which then carried the donor water 50 km downstream to Lake Lavon.
2. Baseline (pre-transfer) data on the composition of fish assemblages at seven stations on the creek or at its confluence with the receiving reservoir were collected monthly for 3 years, and similar data were collected for 2 years during and after trial flows of Lake Texoma water to Sister Grove Creek. We also documented fish abundance at five creek stations immediately before and after three trial flow periods of 10–14 days each in summer and autumn.
3. Multivariate analysis of all routine monthly samples over the 5-year pre- and post-transfer period showed moderate changes in the fish fauna of the creek after initiation of the trial flows. Samples taken within a week before and after the artificial high flows showed little overall change in abundance of individual fish species, but at some stations the quantitative or qualitative change in composition of the local assemblage was substantial.
4. The trial flows lasted 2 weeks or less. Long-term effects of water transfer on the fish fauna of Sister Grove Creek can only be determined after the conveyance system goes into normal operation, with periods of artificial flow of longer duration.     

Advective effects of a reservoir flood on zooplankton abundance and dispersion

SUMMARY. 1. The diel vertical distribution and abundance of zooplankton in the Red River arm of Lake Texoma, Oklahoma-Texas, U.S.A., were examined between 25 January and 26 June 1982.
2. During periods of low river inflow, zooplankton vertical patchiness was related to wind stress. Zooplankton did not maintain distinct vertical patches under strong mixing.
3. In mid May heavy rainfall in the drainage basin increased discharge from the Red River and reduced water retention time in the reservoir. The Red River water mass entered the lake as a turbid, surface overflow plume. During this period of flooding most zooplankton populations declined and the distributions of remaining individuals deepened. Greatest population losses occurred between 0 and 7m, depths where most zooplankton had been concentrated prior to the flood.
4. A model of population dynamics based on depth specific rates of water exchange between the lake and the Red River, estimated from conductivity changes through time, accounted for the general pattern of change in zooplankton abundance and vertical dispersion.     

Temporal and spatial patterns in littoral-zone fish assemblages of a reservoir (Lake Texoma,Oklahoma-Texas,U.S.A.)

Synopsis We sampled the littoral-zone fish fauna of Lake Texoma reservoir by electrofishing from January through December 1986 to examine species abundance, species associations and assemblage structure. Although total fish abundance differed significantly across seasons, only one common species (Dorosoma cepedianum) exhibited significant seasonal movement into or out of the littoral zone. Overall littoral-zone assemblage structure (based on rank order of species abundance) was concordant across seasons and habitat types, (vegetation, wood, open). However, within individual seasons and habitat types, assemblage structure was likely influenced by temporal and spatial differences in habitat availability and physicochemical conditions. Associations characteristic of species in natural aquatic environments were not well developed among species in this partly artificial, evolutionarily short-lived reservoir assemblage. Conditions related to water-level fluctuation appeared to deter the formation of persistent species associations and assemblage structure, especially in vegetation and open littoral zone habitats of this multi-purpose reservoir.Senior author     

Association of Large Juvenile Red Drum, Sciaenops ocellatus, with an Estuarine Creek on the Atlantic Coast of Florida

Seasonal abundance, size distribution, year-class presence, residence duration, and migrational patterns of red drum, Sciaenops ocellatus, in an estuarine marsh creek in the northern Indian River Lagoon, Florida, were investigated during a study in which gill net samples were collected monthly from August 1991 to March 1996. A total of 282 large juvenile red drum were collected, of which 161 were tagged and released and 68 were sacrificed for age determination. Although red drum were collected in the creek throughout the year, abundance levels were negatively correlated with water temperatures and reached maximum levels during the winter months. Significant correlations between fish abundance and salinity or dissolved oxygen levels were not detected. The majority (90%) of the fish collected were large juveniles (260–450mm standard length) that were estimated to be from 10 to 26 months old. The oldest red drum we examined from the creek was estimated to be 37 months old. Tag-recapture data indicated that some fish repeatedly used or were associated with the creek for periods of up to 18 months after release. Estuarine creeks in this region provide exploitable habitat for large juvenile red drum (相似文献   

Drift patterns of particulate matter and organisms during artificial high flows in a large experimental channel

Using a large experimental channel, five artificial high flows with different flow regimes were launched to reveal the precise temporal sequences of drifting particulate matter and organisms during the high flows. Drifting fine particulate matter and organisms were collected by sampling bottles and a water pump, respectively. The peaks of drift abundance occurred before the peak discharges, and the abundance declined quickly within several minutes during the rising phase of high flows. The major determinant of drift abundance of particulate matter and organisms was periods of stable conditions before each high flow (tested by determination coefficients in a correlation analysis). The drift of macroscopic plant material also accelerated the drifts of epiphytic fauna and infauna, which drifted with plants and bed sediments. The magnitude (discharge and duration of peak flows) of high flows only slightly affected drift abundance. The fauna more resistant to high flows were invertebrates that fasten their cases or retreats by silk threads on the substrata. Invertebrate taxa having sucking apparatus or high swimming activity were also resistant to high flows.     

The effects of heavy metals pollution of the upper Arkansas River on the distribution of aquatic macroinvertebrates

Water quality, types, and diversity of aquatic macroinvertebrates show that heavy metal pollution of the upper Arkansas River is presently moderately severe and conditions for aquatic life are generally poor, particularly in the Leadville area. A 2 year study was done on a 30 km section of the upper Arkansas River, Colorado, to determine the effects of heavy metals pollution on the distribution of the aquatic macroinvertebrates. Physical and chemical water parameters were measured, and aquatic macroinvertebrates were collected. The major sources of heavy metal-laden inflows are Leadville Drain, California Gulch, and a number of intermittent flows entering the Arkansas River between Lake Fork and Lake Creek. Important freshening flows are Tennessee Creek, Lake Fork (containing Halfmoon Creek), and Lake Creek.     

Fish fauna, biogeography and conservation of freshwater fish in Poyang Lake Basin, China

A checklist of the fish of Poyang Lake Basin based on an extensive survey and literature review is presented. A total of 220 species and subspecies belonging to12 orders, 27 families and 100 genera, have been recorded. Of these, 131 species are endemic to China. Based on cluster analysis with presence-absence data, freshwater ecosystems in Jiangxi Province are divided into two regions, the Xunwushui River region and the region of Poyang Lake. The Xunwushui River flows into the Pearl River, whereas the region of Poyang Lake flows into the Yangtze River. The fish fauna and evolution of the fish fauna in Poyang Lake Basin owes much to geological events and belongs to the Oriental Region, South-east Asiatic sub-region and East China area. Anthropogenic activities including habitat alteration, overfishing, pollution and soil erosion have severely reduced the fish biodiversity in Poyang Lake Basin. River modifications (i.e. dam construction and sand excavation) and heavy metal pollution are the most significant threats to fish diversity and ecosystem functioning in the majority of the river systems in the province. To protect fish diversity and fisheries more effectively in Poyang Lake Basin, law enforcement should be strengthened, and the following measures could be introduced: restocking economically important fish species; establishing fish sanctuaries and freshwater protected areas, ordering a close season and developing sustainable aquaculture.     

Effects of damming on the biological integrity of fish assemblages in the middle Lancang-Mekong River basin

The Lancang-Mekong River basin contains a diverse assemblage of freshwater fish species; however, their populations are threatened by current and planned dam construction along the river. Fish assemblages are sensitive indicators of environmental degradation and can be used to assess aquatic ecosystem health. This research compared the fish fauna at the Xiaowan hydropower dam located on the middle reaches of the Lancang-Mekong River at three time periods: in 2008 (before impoundment), 2010 (water storage) and 2011 (full operation). A modified fish index of biological integrity (modified F-IBI) was developed and it synthesized information on the taxonomic composition, trophic guilds, and tolerance levels of the fish and habitat diversity to quantitatively assess the condition of fish populations before and after damming. This index also was used to assess the longitudinal diversity of the fish fauna along the river channel and could assess the barrier effect associated with the dam. Jaccard's index of similarity was used as a feasible tool to assess fish diversity loss and biotic homogenization. The analysis clearly showed a homogenization of the fish communities after damming, and the reservoir impoundment region showed much more serious homogenization than the downstream region. The Xiaowan dam had an immediate and profound effect on the fish fauna in this region of the Lancang-Mekong River. A total of eight cascading dams are planned for development in this region, and, unless conservation mitigation efforts are considered, the results could be devastating on the native fish populations of middle reaches of the Lancang-Mekong River basin.     

Fish population changes in the Volta lake in Ghana during its first sixteen months

Summary A study has been made on changes which have occurred in the fish fauna as a result of the formation of the Volta Lake in Ghana. The data on the relative abundance of fish in the Lake were compared with those obtained from fish landings on the Black Volta and from the Niger river survey, as no observations of fish abundance were made on the Volta River before the Akosombo dam was closed. General changes in the relative abundance of the most important families of fish are described and the changes in the relative abundance of six feeding types in the Volta Lake and Black Volta, based on more than 700 stomach and gut analyses of 50 species of fish, are compared with those of the fish found in the Zambezi River and Lake Kariba in Central Africa.The most characteristic features of the changes in fish fauna are an increase in plankton feeders, so that these are becoming dominant in some areas; a great decrease in mormyrids in the Lake as compared with the river, and a similar drop in the characid Alestes, while Tilapia has increased. These changes are not uniform throughout the lake, and differences are most marked along the North-South axis.Department of Zoology and Volta Basin Research Project, University of Ghana     

Relationship between flow regime and fish abundances in a gravel‐bed river, New Zealand

The key elements of the flow regime of the Waipara River on the east coast of New Zealand, that affected fish abundances were the timing of floods and the magnitude and duration of low flows. Generally, fish abundances were highest in early summer, and lowest at the beginning of winter. Spring floods opened the river mouth, allowing recruitment of diadromous fish species, and non‐diadromous fish species spawned after the floods in spring or early summer. Reductions in fish abundances over summer and autumn were consistent with the magnitude and duration of low flows, with significant reductions in the year of lowest flow and little change in abundance in the year when low flows were highest. Variations in fish abundances during periods of low flow were consistent with the amount of instream habitat available, such that abundances of species with high velocity preferences decreased during periods of low flow, whereas abundances of species with low velocity preferences increased.     

Impact of acid mine-drainage from abandoned spoils on the chemistry of an intermittent stream in the arid Southwest

Drainage from an orphaned copper mine (Sheldon Mine Complex) contributes highly mineralized, acidic waters to Lynx Creek, a small intermittent, arid-climate stream. This results in localized elevation of major cations, silica, sulfate, and heavy metals (Cu, Fe, Mn, Zn), depression in pH, and complete neutralization of bicarbonate alkalinity. Levels of chloride, nitrogen and phosphorus are unaffected by mine-drainage. During stable flow, water quality of the creek improves downstream through precipitation of metal salts, dilution by less mineralized tributaries, and additional buffering from the creek channel and tributaries. Climatic aridity, via high evaporation, concentrates and precipitates metal salts during summertime periods of low flow. Creek sediments thus contain large amounts of heavy metals and phosphorus that are transported downstream in suspended particulates during spates. This reflects an annual cycle of temporary creek-bed storage followed by episodic mobilization toward Lynx Lake, a downstream reservoir. Although the influence of mine drainage is not overtly apparent in the dissolved chemistry of the Lake, high concentrations of metals and phosphorus occur in lake sediments.Represents a portion of a thesis by A. J. L. III submitted in partial fulfillment of the requirements of a M.S. Degree in Botany, Arizona State University.     

Long-term changes of planktonic rotifers in a subtropical Chinese lake dominated by filter-feeding fishes

1. The long-term changes (1956–1998) in density and species composition of planktonic rotifers were studied at two sampling stations (I, II) of Lake Donghu, a shallow eutrophic Chinese Lake densely stocked with filter-feeding fishes. Annual average densities of rotifers increased with an increase in fish yield and eutrophication, whilst species number decreased from 82 in 1962–1963 to 62 in 1994–1998.
2. During 1962–98, some species such as Anuraeopsis fissa , Polyarthra spp. (including P. dolichoptera & P. vulgaris ) , Trichocerca pusilla and Synchaeta oblonga increased their percentage in abundance remarkably, whilst the proportion of Keratella cochlearis decreased at two relatively eutrophic stations from 19 to 4.2% at Station I and from 30 to 3.2% at Station II.
3. The high r _max of A. fissa probably made it more successful than other rotifers under high predation pressure by planktivorous fish. The decrease in the K. cochlearis population might be attributed partly to predation by Cyclops vicinus .
4. Small rotifers were less vulnerable to fish predation than large-sized cladocerans. Decreases in cladocerans coincided with increases in rotifers, suggesting that the indirect effect of fish predation on cladocerans might have partly contributed to the population development of rotifers in Lake Donghu during recent decades.
5. We also conducted surveys (1994–1998) of seasonal dynamics of rotifers at four sampling stations (I–IV) which have varied in trophic status after fragmentation of the lake in the 1960s. A total of 75 species were identified at the four stations. Both densities and biomass of rotifers were considerably higher in the two more eutrophic stations than in the two less eutrophic stations. This indicates that the population increase of rotifers at Stations I and II during recent decades might be partly attributed to eutrophication of the lake water.     

Development and validation of a Biotic Index for evaluation of environmental quality in the central region of Argentina

The Suquía River (Córdoba, Argentina) has become an important issue because it flows into Mar Chiquita Lake, one of the largest saline lakes in the world. This water body, together with the expansive swamps of the Dulce River on the northern shore and the mouth of Suquía and Xanaes River, is considered one of the most important wetlands in Argentina in terms of biodiversity in a range of freshwater to very saline environments. Nevertheless, the presence of densely populated urban settlements and the increasing environmental impact due to anthropogenic activities characterize the central and lower sections of Suquía River Basin. Fishes are particularly affected and change their distribution and abundance as a consequence of the environmental deterioration. We collected information on fish fauna to develop and validate a Biotic Index to assess degradation of the Suquía River Basin. We classified fish species according to their sensitiveness or tolerance to environmental degradation, based on their distribution and abundance variations along a water quality gradient in order to design a Biotic Index for Suquía River Basin. The set of metrics used in the Biotic Index calculation was conformed by: the abundance of Astyanax eigenmanniorum, Rineloricaria catamarcensis, Gambusia affinis and Cnesterodon decemmacultus, the proportion of sensitive species richness, and the proportion of tolerant species richness. They clearly distinguished between the impaired and referenced sites. We demonstrated that it is possible to use fish as indicators of water quality in Córdoba Province (central part of Argentina) in order to carry out rapid and relatively inexpensive monitoring and conservation programs. The application of this Biotic Index showed that fish assemblages reflect the watershed conditions and are sensitive to changes in water quality across the environmental gradient.     

Flow-related patterns in abundance and composition of the fish fauna of a degraded Australian lowland river

1. A 7‐year study was conducted in three hydrologically distinct sections within the highly regulated, lowland Campaspe River to investigate the influence of hydrology on temporal and spatial patterns in fish composition, abundance and recruitment. One section had 6 months, one section 2 months and one section no months of increased flow due to storage releases. The fish fauna of the less regulated, nearby Broken River served as a reference to which that of the Campaspe River was compared for the last 3 years of the study to allow insight into the relative effects of hydrology, barriers to movement and other environmental characteristics. The study included one high‐flow year, a moderate‐flow year and five low‐flow years. 2. A total of 16 fish species – 10 native and six alien – were caught in the Campaspe River, although of the native species, only three are considered to have self‐sustaining populations. The remaining species are either itinerants or a result of stocking. Alien species comprised approximately 64% of the total biomass of all fish caught. 3. Overall composition of the fish fauna did not differ significantly by year, but did by section of river. Species richness and the abundance of most of the dominant species also differed significantly by river section, but there was little inter‐annual variation in the abundance of any species, except for European perch and for common carp; the latter showing an increase in abundance following a high‐flow event during the spring of 2000 as a result of recruitment. 4. Overall faunal composition was not influenced by hydrology. However, multiple regression indicated that species richness, abundance of the dominant species and abundance of young‐of‐year (YOY) of golden perch, European perch and common carp all were influenced significantly by hydrological variables. The nature of the relationships was dependent on river section and hydrological season (‘winter’ or ‘spring/summer’). Of note was the result that the total abundance of fish and that of YOY common carp were significantly positively related to the number of spells above the threshold for movement upstream through the lower two weirs in the Campaspe River. Only one significant relationship between hydrological and fish‐related variables was found for the upper river section, whereas seven and five were found for the lower and middle sections respectively. 5. Comparisons with fish collected in the Broken River over 3 years suggest that the fauna of the Broken River is in a more natural state than that of the Campaspe River. Since the two rivers do not differ substantially in water quality, and since both contain significant weirs, which act as barriers to movement of fish, flow regulation is most likely to be the major reason for the poor state of the fauna in the Campaspe River.     

Daily Fish and Zooplankton Abundances in the Littoral Zone of Lake Texoma,Oklahoma-Texas,in Relation to Abiotic Variables

Many studies have shown the effects of yearly or monthly environmental conditions on the structure of fish and zooplankton communities. Environmental conditions can also vary greatly on much shorter time scales. We tested the effects of abiotic conditions on the daily abundance of fish and zooplankton in the littoral zone of Lake Texoma, Oklahoma-Texas. After date was removed statistically from the analysis, no environmental variables were particularly important in determining the daily abundance of zooplankton, whereas, numbers of fish in the littoral zone were related to changes in wind velocity and wave height. Regressions of daily fish abundance against wave height showed that the response differed among species and among life-history intervals within species. Numbers of juvenile Dorosoma petenense, Notropis atherinoides, and Morone chrysops were positively correlated with wave height, whereas juvenile Menidia beryllina were negatively correlated with wave height. We suggest that changes in the abundance of particular species may be associated with (1) avoidance of inshore areas to escape possible physical damage by wave induced turbulence, (2) attraction to inshore areas to feed on prey organisms suspended in the water column by wave induced turbulence, and (3) avoidance of inshore areas to escape high predator abundance and increased possibility of being eaten due to turbulence.     

Temporal and spatial distributions of the fish larval assemblages of the Ivinheima River sub-basin (Brazil)

Fish, like other animals, choose environments for reproduction that are favorable for their offspring’s initial development. For example, these environments may be chosen to provide shelter and food. This study examined the fish larvae inhabiting the Ivinheima River sub-basin. The study aimed to (i) characterize the taxonomic composition of the larval fish fauna, (ii) analyze the structure of the larval assemblage, and (iii) verify the relationship between the larval assemblages and environmental variables. The sampling areas included three environments: the Ivinheima River, the Finado Raimundo Lagoon and the Patos Lagoon. Sampling was performed between October 2002 and March 2006 during four reproductive periods (RPs). The data were analyzed with correspondence analysis (CA) and canonical correlation analysis (CCA). A total of 120 619 larvae were collected. These larvae belonged to several species characterized by different reproductive strategies. Our results showed differences between the composition of the Ivinheima River’s assemblages, where there were more larvae of migratory fish, and the lagoons, where larvae of sedentary species were predominant. In addition, differences were found among the RPs evaluated in the Ivinheima River: the first and second RPs were characterized by milder floods and by a greater abundance of migratory piscivore larvae, whereas the third and fourth RPs had more outflow and a greater abundance of larvae of detritivore and omnivore species. We conclude that the Ivinheima River plays a significant role in the maintenance of native migratory fish stocks in the upper Paraná River basin and that the environment shows a segregation of the spatial and temporal composition and abundance of larvae related to running and flooding/standing water.     

Benthic metabolism in two turbid dryland rivers

1. Australian dryland rivers have among the most variable discharge of any rivers worldwide and are characterized by extended periods of no flow during which aquatic habitat contracts into isolated waterholes. Despite naturally high turbidity, benthic primary production is known to be the main source of carbon to waterhole food webs. The objective of this study was to quantify rates of benthic metabolism and identify factors influencing these rates in two Australian dryland rivers, the Cooper Creek and the Warrego River. 2. Both rivers have similar variable hydrology and high levels of turbidity (photic depths < 0.4 m), but fish abundance in Cooper Creek is 10 times than that of the Warrego River. Therefore, an additional aim of the study was to determine if fish abundances reflected underlying differences in benthic primary production. 3. Benthic gross primary production (GPP), benthic respiration, nutrient concentrations and light penetration were measured immediately after flow had ceased (‘post‐flow’) and after at least 2 months of zero flow (‘no‐flow’) in 15 waterholes from each river. A subset of four waterholes from each river was sampled on two additional occasions to determine if patterns were consistent over time. 4. Cooper Creek generally had higher rates of GPP and a more autotrophic benthic zone than the Warrego River. As a result, the expected positive relationship between fish abundance and GPP was generally observed at a broad catchment scale. 4. Light was the major control in benthic GPP in both rivers, as nutrient concentrations were high on all sampling occasions. However, for similar values of photic depth, GPP was greater in Cooper Creek than in the Warrego River. This suggests that more frequent disturbance of the littoral zone may inhibit biofilm development in waterholes of the Warrego River. 5. Although flow variability in dryland rivers is extreme compared with other rivers worldwide, cycles of expansion and contraction of aquatic habitat in these two rivers were associated with a shift in the dominance of regional scale (subcatchments contributing to river flow) versus local scale (waterhole morphology) influences on ecosystem functioning, similar to floodplain rivers in tropical and temperate regions.     

Occurrence of Bunodera sacculata Van Cleave and Mueller, 1932 in Perca flavescens from Silver Creek and Silver Lake,Michigan

Bunodera sacculata (Trematoda: Allocreadiidae) infected 65 (54%) of 120 yellow perch collected in 1997 and 40 (50%) of 80 perch from Silver Creek in 1998. and 17 (30%) of 56 perch in 2000 from Silver Lake in lower Michigan. Gravid B. sacculata occurred in the pyloric ceca and anterior intestine. There were differences in monthly trends (July through August) in prevalences, mean intensities, and mean abundances of B. sacculata in Silver Creek between 1997 and 1998. The mean intensity +/- SD (8.2 +/- 9.1) and mean abundance (4.1 +/- 7.8) of B. sacculata were significantly higher in 1998 than in 1997 and 2000. An additional 20 perch (0+ in age) collected from the creek in July 1998 were all infected and had the highest mean intensity of 21.3 +/- 14.1.     

The influence of hydrology on the structure of invertebrate communities in two streams flowing into Lake Nakuru,Kenya

Stream fauna communities were studied in the Baharini Springbrook and the Njoro River, which flow into Lake Nakuru. The streams have significantly different flow regimes. Consequently, discharge-related factors influence their faunal composition and abundance. The Baharini Springbrook is perennial, slow-flowing with low steady discharge, a higher conductivity and a low conductivity gradient along its course. The Njoro River is intermittent, fast-flowing with a higher and variable discharge, lower conductivity and a steeper conductivity gradient. Due to its permanent and steady surface stream flow, the Baharini Springbrook has a higher number of invertebrate species and higher abundances than the Njoro River. However, in spite of the intermittent nature of the Njoro River, during periods of relatively steady discharge the composition of its fauna is similar to that of the Baharini Springbrook. Similarity in the substratum characteristics of the two streams and their close proximity is a possible explanation for the close relationship in their faunal composition. At the onset of flow after a drought, rapid colonisation of the lowland intermittent stretch of the Njoro River occurred probably by drift from upstream perennial sections and/or from the hyporheos. Initial small spates at the onset of surface flow seem not to affect the invertebrate abundance, but later bigger spates during and after much heavier rains reduced the faunal abundance significantly. The recovery of faunal abundance to pre-flood levels in the Njoro River was completed in 27 days. Taxon richness was, however, less affected by the spates.     

Longitudinal changes and indicator species of the fish fauna in the subtropical Sinos River, Brazil

This study investigated the fish fauna in the subtropical Sinos River, considering species addition and replacement and the occurrence of indicator species along a longitudinal gradient. Patterns in fish assemblage ordination evaluated by correspondence analysis reflected the headwater and lowland river reaches. Uppermost sampling stations were characterized by species with restricted occurrence and medium abundance, whereas in the lowland most species were captured only once during the surveyed period and in low abundance. Species addition prevailed between the headwater sampling stations and both addition and replacement occurred between the lowland sampling stations. Nine species were characteristic for the headwater reach and 14 species for the lowland reach.