Rainfall events and downstream drift of microcrustacean zooplankton in a Newfoundland boreal stream

2002 ◽  
Vol 80 (6) ◽  
pp. 997-1003 ◽  
Author(s):  
Christine E Campbell
Keyword(s):  
Invertebrate Drift ◽  
Zooplankton Abundance ◽  
Strongly Correlated ◽  
Upstream Site ◽  
Rainfall Events ◽  
Flushing Rate ◽  
Stream Discharge ◽  
Stream Productivity ◽  
High Precipitation ◽  
Zooplankton Drift

While rainfall events may lead to flushing of zooplankton from lakes, with implications for stream productivity near lake outlets, consideration also needs to be given to zooplankton transported farther downstream. To evaluate such downstream transport, daytime invertebrate drift, stream discharge, and rainfall events were monitored over 4 summers in Cook's Brook, Newfoundland, at a downstream site 1.0 km below the outlet of Big Cook's Pond and an upstream site 1.0 km upstream of the pond. Microcrustacean zooplankton were abundant in some downstream samples; high percent zooplankton abundance (87–94%) corresponded to the highest total invertebrate drift densities. Percent zooplankton in downstream drift was strongly correlated with recent rainfall (rS = 0.815, p = 0.025) and stream discharge (rS = 0.964, p = 0.001). The majority of microcrustaceans in the drift were planktonic cladocerans and copepods, the species composition being similar to that in Big Cook's Pond. No zooplankton were ever collected from the upstream site. Ephemeroptera, Diptera, Trichoptera, and Ostracoda were abundant in most drift samples. Zooplankton drift (mean = 0.17 individuals/m3) in Cook's Brook appears to be catastrophic drift, with high precipitation rates and resultant increased flushing rate in Big Cook's Pond leading to "washout" of microcrustaceans 1 km downstream.

scholarly journals Soil carbon and nitrogen erosion in forested catchments: implications for erosion-induced terrestrial carbon sequestration

2015 ◽  
Vol 12 (16) ◽  
pp. 4861-4874 ◽  
Author(s):  
E. M. Stacy ◽  
S. C. Hart ◽  
C. T. Hunsaker ◽  
D. W. Johnson ◽  
A. A. Berhe
Keyword(s):  
Organic Matter ◽  
Sierra Nevada ◽  
Sediment Yield ◽  
Forest Ecosystems ◽  
Mineral Particle ◽  
Strongly Correlated ◽  
Terrestrial Carbon ◽  
Stream Discharge ◽  
C And N ◽  
Sediment Export

Abstract. Lateral movement of organic matter (OM) due to erosion is now considered an important flux term in terrestrial carbon (C) and nitrogen (N) budgets, yet most published studies on the role of erosion focus on agricultural or grassland ecosystems. To date, little information is available on the rate and nature of OM eroded from forest ecosystems. We present annual sediment composition and yield, for water years 2005–2011, from eight catchments in the southern part of the Sierra Nevada, California. Sediment was compared to soil at three different landform positions from the source slopes to determine if there is selective transport of organic matter or different mineral particle size classes. Sediment export varied from 0.4 to 177 kg ha−1, while export of C in sediment was between 0.025 and 4.2 kg C ha−1 and export of N in sediment was between 0.001 and 0.04 kg N ha−1. Sediment yield and composition showed high interannual variation. In our study catchments, erosion laterally mobilized OM-rich litter material and topsoil, some of which enters streams owing to the catchment topography where steep slopes border stream channels. Annual lateral sediment export was positively and strongly correlated with stream discharge, while C and N concentrations were both negatively correlated with stream discharge; hence, C : N ratios were not strongly correlated to sediment yield. Our results suggest that stream discharge, more than sediment source, is a primary factor controlling the magnitude of C and N export from upland forest catchments. The OM-rich nature of eroded sediment raises important questions about the fate of the eroded OM. If a large fraction of the soil organic matter (SOM) eroded from forest ecosystems is lost during transport or after deposition, the contribution of forest ecosystems to the erosion-induced C sink is likely to be small (compared to croplands and grasslands).

Triazine herbicide contamination of Tasmanian streams: Sources, concentrations and effects on biota

1994 ◽  
Vol 45 (2) ◽  
pp. 209 ◽  
Author(s):  
PE Davies ◽  
LSJ Cook ◽  
JL Barton
Keyword(s):  
Surface Waters ◽  
Biological Effects ◽  
Invertebrate Drift ◽  
Triazine Herbicide ◽  
Short Term ◽  
Rainfall Events ◽  
Agricultural Catchments ◽  
Stream Communities ◽  
Forestry Industry ◽  
Forestry Plantations

Concentrations of the triazine herbicides atrazine, simazine, cyanazine, metribuzin and propazine were determined in streams draining forestry and agricultural catchments in Tasmania, Australia, between 1989 and 1992. Atrazine and simazine were used extensively by the forestry industry in a winter spraying programme, and applications of the other herbicides occurred in cropped agricultural catchments during spring and summer. Of 29 streams sampled intensively for triazines, 20 contained detectable residues. Median contaminations over all samples were 2.85, 1.05, <0.05, <0.05 and <0.05 �g L-1 for atrazine, simazine, cyanazine, metribuzin and propazine, respectively. All herbicide concentrations ranged over several orders of magnitude up to 53 mg L-1, with atrazine and simazine having significantly higher concentrations than the others. Atrazine concentrations were examined in streams draining forestry plantations for periods of up to two years. A decline in concentration was observed with time, but this was strongly influenced by rainfall events. Atrazine contamination from single spraying events persisted at a low level for up to 16 months. Contamination of Big Creek with atrazine to 22�g L-1 after aerial spraying led to an increase in stream invertebrate drift only on the day of spraying and to a short-term increase in movement of brown trout. On examination of biological effects of triazines in surface waters reported in the literature, it was concluded that the observed frequent contamination of Tasmanian streams with triazines may cause occasional minor short-term disturbance to stream communities.

Staple strength of fine, medium and strong wool Merino wethers under drought conditions

2006 ◽  
Vol 46 (9) ◽  
pp. 1123
Author(s):  
M. A. Friend ◽  
G. E. Robards
Keyword(s):  
Coefficient Of Variation ◽  
Management Strategies ◽  
Fibre Diameter ◽  
Summer Rainfall ◽  
Arid Environment ◽  
Strongly Correlated ◽  
Rainfall Events ◽  
Treatment Groups ◽  
Effect Of Treatment ◽  
Staple Strength

Fine, medium and strong wool Merino wethers (n = 72, 4 years old) were grazed together on drought-affected pastures in a semi-arid environment. In order to examine the hypothesis that restricting liveweight gains at the break of drought would improve staple strength, sheep were allocated to restricted grazing in a 5-ha paddock (drought group), or unrestricted grazing in a 20-ha paddock (drought-break group) when it was judged that the drought had broken in the region. Wool staples from all sheep broke at a point coinciding with summer rainfall events before allocation to treatment groups, and staple strength did not differ between treatments. Medium wool sheep (22.0 ± 1.6 N/ktex) produced wool of lower (P<0.001) staple strength than fine (30.0 ± 1.6 N/ktex) or strong (30.2 ± 1.6 N/ktex) wool sheep. Restricting the measurement of staple strength to the period when treatments were applied revealed no effect of treatment on staple strength, despite the fact that wethers in the drought-break group experienced a greater (P<0.001) liveweight gain (6.62 ± 0.37 kg) after allocation to their treatment than those in the drought group (–3.24 ± 0.37 kg). Staple strength was most strongly correlated with coefficient of variation of fibre diameter (r = –0.65; P<0.001); a result that was observed for all strains and treatment groups. The results indicate that coefficient of variation of fibre diameter is correlated with staple strength regardless of strain, and that management strategies designed to limit fibre diameter variability during a drought need to be applied not only at the break of a drought.

scholarly journals Assessing methods for the estimation of response times of stream discharge: the role of rainfall duration

2019 ◽  
Vol 67 (2) ◽  
pp. 143-153 ◽  
Author(s):  
Jaime G. Cuevas ◽  
José L. Arumí ◽  
José Dörner
Keyword(s):  
Response Times ◽  
Stream Velocity ◽  
Middle Point ◽  
Rainfall Events ◽  
Average Value ◽  
Stream Discharge ◽  
Rainfall Duration ◽  
Watershed Dynamics ◽  
The Mean

Abstract Lagtimes and times of concentration are frequently determined parameters in hydrological design and greatly aid in understanding natural watershed dynamics. In unmonitored catchments, they are usually calculated using empirical or semiempirical equations developed in other studies, without critically considering where those equations were obtained and what basic assumptions they entailed. In this study, we determined the lagtimes (LT) between the middle point of rainfall events and the discharge peaks in a watershed characterized by volcanic soils and swamp forests in southern Chile. Our results were compared with calculations from 24 equations found in the literature. The mean LT for 100 episodes was 20 hours (ranging between 0.6–58.5 hours). Most formulae that only included physiographic predictors severely underestimated the mean LT, while those including the rainfall intensity or stream velocity showed better agreement with the average value. The duration of the rainfall events related significantly and positively with LTs. Thus, we accounted for varying LTs within the same watershed by including the rainfall duration in the equations that showed the best results, consequently improving our predictions. Izzard and velocity methods are recommended, and we suggest that lagtimes and times of concentration must be locally determined with hyetograph-hydrograph analyses, in addition to explicitly considering precipitation patterns.

scholarly journals Biotic controls on solute distribution and transport in headwater catchments

2015 ◽  
Vol 12 (1) ◽  
pp. 213-243 ◽  
Author(s):  
E. M. Herndon ◽  
A. L. Dere ◽  
P. L. Sullivan ◽  
D. Norris ◽  
B. Reynolds ◽  
...  
Keyword(s):  
Organic Matter ◽  
Stream Water ◽  
Solution Chemistry ◽  
Pore Waters ◽  
Rainfall Events ◽  
Headwater Catchments ◽  
Stream Discharge ◽  
Weak Complexes ◽  
Concentration Behavior ◽  
Shale Hills

Abstract. Solute concentrations in stream water vary with discharge in patterns that record complex feedbacks between hydrologic and biogeochemical processes. In a comparison of headwater catchments underlain by shale in Pennsylvania, USA (Shale Hills) and Wales, UK (Plynlimon), dissimilar concentration-discharge behaviors are best explained by contrasting landscape distributions of soil solution chemistry – especially dissolved organic carbon (DOC) – that have been established by patterns of vegetation. Specifically, elements that are concentrated in organic-rich soils due to biotic cycling (Mn, Ca, K) or that form strong complexes with DOC (Fe, Al) are spatially heterogeneous in pore waters because organic matter is heterogeneously distributed across the catchments. These solutes exhibit non-chemostatic "bioactive" behavior in the streams, and solute concentrations either decrease (Shale Hills) or increase (Plynlimon) with increasing discharge. In contrast, solutes that are concentrated in soil minerals and form only weak complexes with DOC (Na, Mg, Si) are spatially homogeneous in pore waters across each catchment. These solutes are chemostatic in that their stream concentrations vary little with stream discharge, likely because these solutes are released quickly from exchange sites in the soils during rainfall events. Differences in the hydrologic connectivity of organic-rich soils to the stream drive differences in concentration behavior between catchments. As such, in catchments where soil organic matter (SOM) is dominantly in lowlands (e.g., Shale Hills), bioactive elements are released to the stream early during rainfall events, whereas in catchments where SOM is dominantly in uplands (e.g., Plynlimon), bioactive elements are released later during rainfall events. The distribution of vegetation and SOM across the landscape is thus a key component for predictive models of solute transport in headwater catchments.

scholarly journals Evaluation of the Use of Some Benthic Macro-invertebrate Multimetric Indices Associations with Environmental Variables in Ecological Assessment of Some Ethiopian Rivers

2017 ◽  
Vol 20 ◽  
pp. 49-54
Author(s):  
Gezahegn Degefe ◽  
Girum Tamire ◽  
Seid Mohammed Hassen ◽  
Abinet Haile
Keyword(s):  
Water Quality ◽  
Ecological Status ◽  
Organic Pollution ◽  
Ecological Assessment ◽  
Biotic Index ◽  
Strongly Correlated ◽  
Upstream Site ◽  
Multimetric Indices ◽  
Biological Quality Elements ◽  
Poor Water Quality

The ecological status of six selected rivers which are found around central Ethiopia and North Shewa Zone and exposed to environmental stresses at varied extent, was studied using biological quality elements (BQE). One thousand one hundred thirty three (1133) individuals of macroinvertebrates, from 22 families and 5 orders of insects, were collected from the rivers. Seven metrics that had low correlation (p>0.05) were selected to calculate the final B-IBI and the result showed that both sites of Akaki, Sebeta and Jemma Rivers had poor water quality whereas Beresa, Chacha and Mojo (upstream site) had relatively better water quality. Canonical Correspondence Analysis (CCA) showed that Tabanidae, Syrphidae, Culicidae, and Canidae was more strongly correlated with temperature but strongly and negatively with pH, Dissolve Oxygen (DO) and Nitrate. The result implied that the change in abundance of these groups of macroinvertebrates could indicate the change in pH, DO and Nitrate. pH and DO were significantly (p < 0.05) and positively correlated with % Ephemeroptera and% Baetidae. On the other hand, DO showed strong but negative correlation % Oligochaeta, % Non-Insect and Hillsenhoff Family Biotic Index which implied that that the change in pH and level of organic pollution can be easily monitored using these metrics.HYDRO Nepal JournalJournal of Water Energy and EnvironmentIssue: 20Page: 49-54

scholarly journals Estuarine zooplankton responses to flood pulses and a hypoxic blackwater event

2021 ◽  
Author(s):  
James Nicholas Hitchcock ◽  
Doug Westhorpe ◽  
William Glamore ◽  
Simon Mitrovic
Keyword(s):  
River Estuary ◽  
Flood Pulse ◽  
Adverse Outcomes ◽  
Zooplankton Abundance ◽  
Rainfall Events ◽  
Hypoxic Conditions ◽  
Poor Water Quality ◽  
Flood Pulses ◽  
Flood Period ◽  
Zooplankton Communities

Flood pulses in estuaries following storms and rainfall events, are short-lived but important moments for a range of ecosystem processes including the delivery of resources and promoting productivity. Conversely some flood pulses can lead to adverse outcomes such as poor water quality conditions. The aim of this study was to determine how zooplankton abundance and community composition responded to flood pulses and if they responded differently during a flood pulse that led to hypoxic conditions. To do this we conducted a two-year observational study in the Hunter River estuary, Australia, monitoring zooplankton communities monthly for a period that covered two major flood pulse events including one that caused widespread hypoxia and a major fish kill. The results showed zooplankton abundance was higher or no different following the 2012 flood when dissolved oxygen remained stable compared to pre-flood conditions. During the 2013 flood when hypoxia occurred the abundance of copepods, nauplii and rotifers were at their lowest for the study period. Zooplankton assemblages were not distinctly different following the 2012 flood pulse compared to the pre-flood period but were different during the hypoxic 2013 flood, though quickly returned to resemble pre-flood conditions in the proceeding months. The study provides useful insights in how zooplankton populations may respond to flood events and recover after hypoxic conditions in estuarine ecosystems.

scholarly journals Aerosol-enhanced high precipitation events near the Himalayan foothills

2020 ◽  
Vol 20 (23) ◽  
pp. 15389-15399
Author(s):  
Goutam Choudhury ◽  
Bhishma Tyagi ◽  
Naresh Krishna Vissa ◽  
Jyotsna Singh ◽  
Chandan Sarangi ◽  
...  
Keyword(s):  
Wave Radiation ◽  
Moist Static Energy ◽  
Average Increase ◽  
Gangetic Plain ◽  
Rainfall Events ◽  
Himalayan Foothills ◽  
High Precipitation Events ◽  
Static Energy ◽  
High Precipitation ◽  
Precipitation Events

Abstract. Particulate emissions can alter the physical and dynamical properties of cloud systems and, in turn, amplify rainfall events over orographic regions downwind of highly polluted urban areas. The Indo-Gangetic Plain, one of the most polluted regions of the world, is located upwind of the Himalayan foothills. The region, therefore, provides an opportunity for studying how aerosol effects, in connection with orographic forcing, affect extreme rainfall events. This study uses 17 years (2001–2017) of observed rain rate, aerosol optical depth (AOD), meteorological reanalysis fields and outgoing long-wave radiation to investigate high precipitation events on the foothills of the Himalayas. Composite analysis of all these co-located data sets for high precipitation events (daily rainfall > 95th percentile) is done to understand the inherent dynamics and linkages between the AOD and extreme events. Clear and robust associations are found between high precipitation events, high aerosol loading and high moist static energy values. Results show an average increase in AOD by 36 %, along with an average increase in low-level moist static energy (1000–850 hPa) by ≈ 1500 J kg−1 inside the selected domain for high precipitation events. The finding highlights the crucial role of the aerosol direct radiative effect on high precipitation events over the Himalayan region.

scholarly journals Landscape heterogeneity drives contrasting concentration–discharge relationships in shale headwater catchments

2015 ◽  
Vol 19 (8) ◽  
pp. 3333-3347 ◽  
Author(s):  
E. M. Herndon ◽  
A. L. Dere ◽  
P. L. Sullivan ◽  
D. Norris ◽  
B. Reynolds ◽  
...  
Keyword(s):  
Organic Matter ◽  
Landscape Heterogeneity ◽  
Stream Water ◽  
Solution Chemistry ◽  
Pore Waters ◽  
Rainfall Events ◽  
Headwater Catchments ◽  
Stream Discharge ◽  
Concentration Behavior ◽  
Shale Hills

Abstract. Solute concentrations in stream water vary with discharge in patterns that record complex feedbacks between hydrologic and biogeochemical processes. In a comparison of three shale-underlain headwater catchments located in Pennsylvania, USA (the forested Shale Hills Critical Zone Observatory), and Wales, UK (the peatland-dominated Upper Hafren and forest-dominated Upper Hore catchments in the Plynlimon forest), dissimilar concentration–discharge (C–Q) behaviors are best explained by contrasting landscape distributions of soil solution chemistry – especially dissolved organic carbon (DOC) – that have been established by patterns of vegetation and soil organic matter (SOM). Specifically, elements that are concentrated in organic-rich soils due to biotic cycling (Mn, Ca, K) or that form strong complexes with DOC (Fe, Al) are spatially heterogeneous in pore waters because organic matter is heterogeneously distributed across the catchments. These solutes exhibit non-chemostatic behavior in the streams, and solute concentrations either decrease (Shale Hills) or increase (Plynlimon) with increasing discharge. In contrast, solutes that are concentrated in soil minerals and form only weak complexes with DOC (Na, Mg, Si) are spatially homogeneous in pore waters across each catchment. These solutes are chemostatic in that their stream concentrations vary little with stream discharge, likely because these solutes are released quickly from exchange sites in the soils during rainfall events. Furthermore, concentration–discharge relationships of non-chemostatic solutes changed following tree harvest in the Upper Hore catchment in Plynlimon, while no changes were observed for chemostatic solutes, underscoring the role of vegetation in regulating the concentrations of certain elements in the stream. These results indicate that differences in the hydrologic connectivity of organic-rich soils to the stream drive differences in concentration behavior between catchments. As such, in catchments where SOM is dominantly in lowlands (e.g., Shale Hills), we infer that non-chemostatic elements associated with organic matter are released to the stream early during rainfall events, whereas in catchments where SOM is dominantly in uplands (e.g., Plynlimon), these non-chemostatic elements are released later during rainfall events. The distribution of SOM across the landscape is thus a key component for predictive models of solute transport in headwater catchments.

scholarly journals The development of a pulsating supraglacial stream

2016 ◽  
Vol 57 (72) ◽  
pp. 31-38 ◽  
Author(s):  
S. L. ST. Germain ◽  
B. J. Moorman
Keyword(s):  
Pulsating Flow ◽  
Rainfall Events ◽  
High Discharge ◽  
Stream Discharge ◽  
Rapid Changes ◽  
Hydrological System ◽  
Meander Bends ◽  
Pool Formation ◽  
Transverse Fractures ◽  
Shear Planes

ABSTRACTSupraglacial streams are a significant part of the glacial hydrological system and important for understanding the connection between glacial hydrology and glacier dynamics. Here we determine the factors that influence the development of step-pool formation and pulsating flow in a supraglacial stream on Bylot Island, Nunavut. Results show that during the second week of a 2-week study, multiple successive rainfall events occurred, stream temperature increased and ablation decreased; which also caused stream discharge to decrease. In addition, the stream, which flowed over a 13 m high waterfall off the front of Fountain Glacier, rapidly formed 21 step-pools and began to pulsate. The pulsating phenomenon involved the complete stoppage of flow over the waterfall and the subsequent restart between 8 and 20 s later. Pulsating flow resulted from rapid changes in the streambed morphology. In particular, the formation of the step-pool sequence was caused by helical flow around meander bends and hydrologically induced slippage along transverse shear planes, evidenced by observations of high-pressure artesian flow from transverse fractures. Contrary to previous literature, this study shows that high discharge is not necessarily the cause of step-pool formation and pulsating flow within supraglacial streams.

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