Geomorphology Erosion • bank and bed erosion - stabilizing role of plant root systems * critical erosion capacity = the lowest velocity needed for a transport of a particle of a given size - lowest for sand (ca 20 cm s_1) Before Measure pin exposure (width) After >> ra O se 03 les ibble i_ (D T3 C bb CO lE es O O es O an pe cr: o DC 1000 Erosion |v velocity E u o o 3 100 10 1 0 0 001 0 01 0.1 1.0 10 Size (mm) 100 1000 FIGIRF 3.8 Relation of mean current velocity in water at least 1 m deep to the size of mineral grains that can be eroded from a bed of material of similar size. Below the velocity sufficient tor erosion of grains of a given size (shown as a band), grains can continue to be transported. Deposition occurs at lower velocities than required for erosion of a particle of a given size. (Reproduced from MorLsawa 1968.) You created this PDF from an application that is not licensed to print to novaPDF printer (http://www.novapdf.com) Geomorphology Sediment load • Suspended load (plaveniny) - usually majority of the total load (5-50 x more than bedload), increases turbidity • Bedload (splaveniny) -<5-10% of the total load but strong impact on the channel shape You created this PDF from an application that is not licensed to print to novaPDF printer (http://www.novapdf.com) Geomorphology Sediment load • Washload - 0.5 u.m-0.625 mm, clay, silt and very fine sand, may never settle out r~ Washload Total Load {defined by source) — Suspended load —i i— In suspension —I '—Bed material load — Along the bed Bed load Total load (defined by mode of transport) FIGURE 3-9 The components of stream sediment load shown in terms of sediment source and mode of transport. (Reproduced from Hicks and Gomez 2003.) You created this PDF from an application that is not licensed to print to novaPDF printer (http://www.novapdf.com) Geomorphology Effect of discharge on sediment transport • stream capacity = total load of sediment the stream can carry FIGURE 3-10 The relationship between frequency and magnitude of discharge events responsible tor sediment transport: (a) suspended load, (b) bcdload. Curve 1 depiets the increase in sediment transport rate with increasing magnitude of discharge, and curve 2 describes the frequency of discharge events of a given magnitude Their product (dashed line) is the discharge that transports the most sediment, referred to as (>tl, the dominant or effective discharge. Qd is approximately Qbkt for suspended sediments, and is in the range Qi^ QUi tor bedltrad. (Reproduced from Richards 1982.) You created this PDF from an application that is not licensed to print to novaPDF printer (http://www.novapdf.com) Abiotic Environment Abiotic environment: Current • boundary layer theory (Davis 1986, Vogel 1994) • laminar (viscous) sublayer 3^ 0<-> y\\ ) O Turbulent region ^- Buffer layer \ Viscous ^ sublayer Wot to Scate i«- Transition Turbulent Water surface Outer layer Logarithmic layer Roughness layer FIGURE 5.3 Subdivision of hydraulicafly rough open-channel How into horizontal layers. Flow velocities within the "roughness layer" are unpredictable based solely on knowledge of flow in the logarithmic layer. This figure is not drawn to scale. (Reproduced from Hart and Finelli 1999.) 0.02 I03 104 -» turbulent flow Fr < 1 —► sutxritical flow Fr = 1 —► eritieal flow Fr > 1 —► super-critical flow r 0 Mean vdOCity Water depth Acceleration due to gravity Kinematic viscosity cm s cm l Measured at OA depth from bottom or from open-channel Total depth, surface to bed 9,8 ms"2 1.004 x 10 (> m2 s 1 at 20 C You created this PDF from an application that is not licensed to print to novaPDF printer (http://www.novapdf.com) Abiotic Environment Influence of substrate roughness on the stream flow • low relative height of roughness elements to channel depth -> very komplex turbulent flow • the role of wood and vegetation FIGURE 5.7 Conceptualization of three types of flow occurring over a rough surface, depending upon differences in relative roughness and longitudinal spacing between roughness elements, (a) Isolated roughness flow, (h) wake interference How; (c) quasi-smooth flow. (Reproduced from Davis and Barmuta 1989, after Chow 1981.) You created this PDF from an application that is not licensed to print to novaPDF printer (http://www.novapdf.com) Abiotic Environment Hydraulic variables II Boundary Reynolds number Re * < 5 —► hydraulieally smooth flow 5 < Re* < 70 -> transitional flow Re* > 70 —► hydraulieally rough flow Re * = rr*/i> Shear velocity em s Substrate roughness em -i FIGURE 5.6 Relationship between roughness Reynolds number and (a) number of invertebrate taxa and (b) macroinvcrtcbrate abundance in sampled areas of 0.07 m2 within three riffles in the Kangaroo River, New South Wales, Australia. Dotted lines indicate 95% confidence intervals. (Reproduced In mi Brooks ct al. 2005.) 0 500 1000 1500 2000 2500 3000 3500 4000 (a) Roughness Reynolds number 2.6 _ 24 22 2.0 1.8 1.6 1.4 12 1.0 0.8 0.6 0.4 0.2 0.0 + o cn o a c 05 "O c D n < ± _L J (b) 500 1000 1500 2000 2500 3000 3500 4000 Roughness Reynolds number You created this PDF from an application that is not licensed to print to novaPDF printer (http://www.novapdf.com) Abiotic Environment Near-bottom flow conditions • very variable • FST - hemisphere method Statzner B. & Müller R. (1989) : Standard hemispheres as indicators of flow characteristics in JVC Spirit Irrt You created this PDF from an application that is not licensed to print to novaPDF printer (http://www.novapdf.com) Abiotic Environment Adaptations of biota to current Baetidae Heptagenidae f You created this PDF from an application that is not licensed to print to novaPDF printer (http://www.novapdf.com) 26 Abiotic Environment Adaptations of biota to current II You created this PDF from an application that is not licensed to print to novaPDF printer (http://www.novapdf.com) Abiotic Environment Response of biota to current Plectrocnemia conspersa (Polycentropodidae): v ~ 0-20 cm/s Hydropsyche instabilis (Hydropsychidae): v ~ 15-100 cm/s Edington (1968) You created this PDF from an application that is not licensed to print to novaPDF printer (http://www.novapdf.com) Abiotic Environment Infuence of current on biota • drag cost, dislocation • increases food, nutrient and gas supply • increases difusion rate on microbe membranes • active and passive colonization: drift, refugee (debris dams, zones of transition, channel edges, hyporheic zone) Ecological processes affected by flow Dispersal • Entrainment • In-stream transport • Settlement Predator-prey interactions • Encounter probability • Escape tactics Competition • Exploitation • Interference • Spacing i +■ Benthic 4 organism / \ Habitat use • Habitat structure • Disturbance regime Resource acquisition • Resource distribution • Capture efficiency • Drag costs FIGURE 5.2 Multiple causal pathways by which flow can affect organisms. Potential interactions among pathways are not shown. (Reproduced from Hart and Finelli 1999.) You created this PDF from an application that is not licensed to print to novaPDF printer (http://www.novapdf.com) Abiotic Environment Temperature • influences physic-chemical processes • influences biological processes - methabolic rate, distribution of organisms along river's length and in different geographic regions, leaf breakdown, nutrient uptake, production • seasonal variation Amazon river ~ 29+1 °C temperate streams: 0-25 °C high altitude and latitude: max. ~ 15°C • cumulative temperature 7000 6000 CO -g 5000 a? 4000 T3 TO I 3000 2000 L 30 32 34 36 38 40 42 Latitude 44 46 48 FIGURE 5.11 Total annual degree-day accumulation (>() Q as a function of latitude for various rivers of the eastern United States. (Reproduced from Vannote and Sweeney 1980.) You created this PDF from an application that is not licensed to print to novaPDF printer (http://www.novapdf.com) Abiotic Environment Variability in water temperature • at the source - T close to that one of groundwater • max. diel variability in wide but shallow rivers (~ 4th order) • spatial variability o o smaller adults -> smaller fecundity • temperature optimum - max. fecundity You created this PDF from an application that is not licensed to print to novaPDF printer (http://www.novapdf.com) Abiotic Environment 1.0 CD ■4—< CO 1 2 CD Q 0.8 - TO b) E g 0.6 - 0.4 - 0.2 - 0 Polypedilum spp. 8 16 24 Temperature (°C) 10 r- lldl'Ki: 5 IK Daily growth rates < nig nig 1 day-1) as a function of temperature tor three aquatic insects found on snag habitat in the Ogeechee River Georgia, and reared in stream-side artificial channels. Insects include the midge Polyfwdihini, the black fly Simtdium, and the mayfly Baetis. (Reproduced from Benke 1993 ) e IS) E Q u 1 001 J_I_I_I_I_L ASONDJ FMAMJJ Months FIGURE 51-1 Lirval growth period tor five species of riffle-inhabiting ephcmerellid mayflies in White Clay Creek, Pennsylvania. (•) Epbetnerella subittna, (A) E. damtbea; (□) SeratelUi deficiens; (■) S. serrata; (inverted open triangle) Euryophella verisimilis. (Reproduced from Sweeney and Vannote 1981.) You created this PDF from an application that is not licensed to print to novaPDF printer (http://www.novapdf.com) Abiotic Environment Factors influencing water temperature in streams Topography upland shading riparian vegetation geology (bedrock) aspect (stream orientation) latitude / altitude Atmospheric conditions solar radiation air temperature wind speed / humidity precipitation (rain / snow) evaporation / condensation phase change (e.g., melting) Streambed Conduction (sediment) hyporheic exchange groundwater input friction (streambed) volume of water slope / water falls turbulence inflow / outflow (Caissie 2006, Freshwat Biol.) Stream discharge You created this PDF from an application that is not licensed to print to novaPDF printer (http://www.novapdf.com) Primary production Primary producers benthic algae, vascular plants, bacteria, protists macrophytes - angiosperms, bryophytes (mosses, liverworts), filamentous growth forms of algae periphyton, phytoplankton epilithon Gathering, shredding and piercing epipelon epipsammon epixylon epiphyton Scraping and gathering Rasping and scraping Crustose Stalked or short Prostrate filamentous ilamentous FIGURE 6.1 Hypothetical representations of major growth forms of periphyton assemblages. Different modes of herbivory are expected to be most effective with particular growth forms. (Reproduced from Steinman 1996.) You created this PDF from an application that is not licensed to print to novaPDF printer (http://www.novapdf.com) Primary production Benthic algae TABLE 6.1 Representation of major peri phy ton taxa in collections where all habitats were sampled, and from studies emphasizing epipelic and epiphytic assemblages. Patrick's (1961) data are from one time of year and include only those species represented by a minimum of six specimens in a very large sample (a count of 8,(X)() individuals) Inclusion of rarer species would at least double the species list. The studies of Moore (1972) and Chudyba (1965, 1968) probably represent close to the entire flora ibr the site. .Xiunber of ta.xa All habitats Efripelon Efrif)byton Diatoms 81a 80b 59c 321d 176c Chlorophyta (green algae) 12 12 32 27 Cyanobactcria (blue-green algae) 9 9 6 14 19 Euglenophyta (phytoflagellatcs) 17 15 - 29 _r Chrysophyta (yellow-brown algae) 0 l i 1 2 Rhodophyta (red algae) I 3 0 0 1 Total 120 120 80 388 225 a Potomac River, Maryland b Savannah River, (ieorgia c White Clay Creek, Pennsylvania (Patrick 1961) d Clay and detritus bottom stream, southern Ontario (Moore 1972) c Epiphytes on Cladoplmraglomerata in the Skawa River, Poland (Chudyba 1965) f Flagellates present but not identified to species You created this PDF from an application that is not licensed to print to novaPDF printer (http://www.novapdf.com) Primary production Primary production gross vs. net promary production biomass accrual per time for macrophytes " small autotrophs - open stream gas exchange, light and dark bottle (chamber) exposure, radiotracer uptake max. 1-6 g C m"2d_1 in shaded stream of temperate zone - 0.01-0.1gCm-2d4 after elimination of grazers, biomass significanly increases scour, export and burial release of DOC Biomass Accrual Resources - Nutrients c Light : Temperature c Biomass Loss High Biomass tow growing, tighty adhering taxa Low Biomass Disturbance □ Substratum instability □ Velocity □ Suspended solids - Grazing - □ Invertebrates □ Fish FIGURE 6.2 Factors controlling the biomass and physical structure of pcriphyton in streams. (Reproduced from Biggs 1996.) You created this PDF from an application that is not licensed to print to novaPDF printer (http://www.novapdf.com) Primary production Influence of light and seasonal variation • high light - filamentous algae • low light - diatoms, cyanobacteria • limiting factor in small streams in forested areas • seasonal variation • studies: shaded vs. unshaded sites, effects of experimental clear-cutting • masking effect of herbivory or limiting concentrations of nutrients Light intensity You created this PDF from an application that is not licensed to print to novaPDF printer (http://www.novapdf.com) Primary production Influence of nutrients • limiting factors generally in freshwaters: 1) P - 2) N:P < 16:1 (10-30:1) -> N becomes limiting, 3) Si and trace metals • constant supply of nutients in running waters - relative ^physiological enrichment" • thickness of periphyton mats • colimitation by N+P FIGURE 6.6 Changes in the numbers of the dominant diatom species in troughs enriched with NO3-N, PG»4-P, or both in combination. Troughs were placed in Carnation Greek, Vancouver Island, allowed -4 weeks to colonize, and then fertilized for 52 days. Note that periphyton populations peaked alter 30-40 days, and then declined sharply prior to termination of the fertilization experiment. (Reproduced from Stockner and Short reed 1978.) 5 D 4 5 I I Others [ I Diatoma hiemale Fragil aria vaucheriae Achnanthes minutissima 20 30 40 Time (days) You created this PDF from an application that is not licensed to print to novaPDF printer (http://www.novapdf.com) Primary production Influence of flow • high streamflow - scouring and abrasion • different community composition in different flow conditions (diatoms, Cladophora) • different growth form in different flow conditions 0) > o 0 Efl o 100r 80 60 40 20 -• • • _L 200 400 600 800 Stone size (I x w, cm2) 1000 FIGURE 6.12 Amount of stone surface covered by the moss Hygrofjyptmm as a function of stone size in a mountain stream. (Reproduced from McAuliffe 1983.) 1000 0 r o sz O 100.0 - E CT) CT3 = 10.0 - JZ Q. O FIGURE 6.11 Chlorophyll a responses to variation in water column velocities (If) in long filamentous green algal communities in the Waiau River, New Zealand. (Reproduced from Biggs ct al. 1998.) You created this PDF from an application that is not licensed to print to novaPDF printer (http://www.novapdf.com) Primary production Phytoplankton • pOtamoplanktOn, displaced Cells Temperature CO Temperature (X) from benthos, backwaters and impoundments • diatoms, cyanobacteria, Chlorophycae • large lowland rivers, slow water current • export up to hundreds km • residence: tens of days • 1-2 doubling per day FIGURE 6.15 Schematic diagram comparing effect of depth of mixing on primary production in phytoplankton of a lake versus a river. In a lake (a), establishment of a temperature barrier between surface and deep waters restricts mixing to uie upper few meters. In a river (b), temperature stratification is impeded by turbulence of flow, and the water column typically mixes from top to bottom. Depths of 5-20 m are common in large rivers. Rivers often carry substantial sediment loads, restricting light penetration to, at best, the upper 1-2 m. You created this PDF from an application that is not licensed to print to novaPDF printer (http://www.novapdf.com) Decomposition Heterotrophic energy sources • allochtonous sources usually dominate the photosynthetic ones • mineralization, storage or export Detrital energy sources TABLE 7.1 Sources or organic matter (OM) to fluvial ecosystems. Sources of input Comments Coarse particulate organic matter ((TOM) • Leaves and needles • Macrophytes during dichack* • Woody debris • Other plant parts (flowers, fruit, pollen) • Other animal parts (feces and carcasses ) Major input in woodland streams, typically pulsed seasonally Locally important May be major biomass component, very slowly utilized Little information available Little information available You created this PDF from an application that is not licensed to print to novaPDF printer (http://www.novapdf.com) Decomposition Leaf breakdown • the loss of leaf mass is loglinear • Wt= Wj x e"kt (Webster & Benfield 1986) Wt... dry mass at time t Wj... initial dry mass k (days-1)... measure of breakdown rate • breakdown rate depends on tempetarure, N availability, pH, hydrological regime • autumn-shed, the loss in april is ca 85% 0 2 4 6 8 Time (week) FIGURE 7.1 Leaf dry mass remaining (as %) from alder ( # ) and willow (O) Icral' packs in an experiment conducted in a Black Forest stream, Germany. Error bars represent 95% confidence Intervals. (Reproduced from Hither and Ciessner 2002.) You created this PDF from an application that is not licensed to print to novaPDF printer (http://www.novapdf.com) Decomposition Braked own rate high N concentration - fast breakdown lignin and celulose - slow breakdown > o 20 50 Half-life (days) 100 200 T > Hydrocharitaceae (6) ♦ Gentianaceae (10) Nymphaeaceae {16) -•- Najadaceae (14) ♦- Pontederiaceae (3) ♦- Podoslemaceae (3) Typhaceae (14) -•- Poaceae (20) Polypodiaceae (5) ■ Cyperaceae (26) • Juncaceae (5) -•- 0.0500 0.0250 0.0100 O.OOSO Breakdown rate (day1) 0.0025 500 - _L 0.0010 20 I 50 I Half-life (days) 100 200 500 —r— Magnoliaceae (3) - Comaceae(l6) ♦ Oleaceae (8) Belulaceae (35) — Salicaceae (33) ■ Ulmaceae (10) — Taxodiaceae (4)- Aceraceae (73) - Myrtaceae (7) - Juglandaceae (23) Platanaceae (14) Fagaceae (105) Ericaceae (16) - -L Pinaceae (38) -L 0.0500 0.0250 0.0100 0.0050 0.0025 0.0010 .1__J______^1- /-J-___— 1 A You created this PDF from an application that is not licensed to print to novaPDF printer (http://www.novapdf.com) Decomposition Leaf breakdown Leaf processing sequence Leaf fall and blow in Microbial colonization physical 9n3 en and softening -*V Process Leaching of soluble components to DOM Amount of weight loss 5-25% Mineralization by microbial respiration toC02 5% Invertebrate colonization continued microbial activity and breakdown Conversion to FPOM Increasing protein content Further microbial conversion 20-35% Feces and fragments 15-25% -30% 10 100 250 Time (days) FIGURE 7.3 The processing or ""conditioning sequence tor a medium-fast deciduous tree leal in a temperate stream. Leached DOM is thought to he rapidly transferred into hiofilms by microbial uptake. You created this PDF from an application that is not licensed to print to novaPDF printer (http://www.novapdf.com) Decomposition Microbial decomposition • aquatic hyphomycetes dominate during 12-18 weeks, up to 30 species, only 2 dominant, nearly no succession • bacteria dominate terminal stage • synergic and antagonistic interaction other macroinvertebrates shredders I I fungi bacteria FIGURE 7.6 Proportions of biomass of bacteria, fungi, shredders, and other macroinvertebrates during alder ind willow leaf decomposition in a Black Forest stream, CTcrmany. (Rcpn)dueed from Hieber and Gcssncr 2002.) 4 6 Time (week) You created this PDF from an application that is not licensed to print to novaPDF printer (http://www.novapdf.com) Decomposition Invertebrate shredders • aquatic insects (e.g., Tipula) and crustaceans • detritovores significantly accelerate decomposition 1 10 100 W Shredder biomass (mg g 1 AFDM) FIGURE 7.10 Correlations between leaf breakdown rates and (a) denialy and (b) biomass of shredders exprcs?>cd per ^ram of leaf AFDM. (Reproduced from Sponsetler and Benficld 2001.) (b) 2 4 6 Time (week) FIGURE 7.9 Colonization of alder (#) and willow (O) leal pucks by (u) macrt)invurtubratu!i and (b) shredders in a Black Forest stream, Germany. Error bars represent 95% confidence intervals. (Reproduced from Hieber and (iessner 2(X)2.) You created this PDF from an application that is not licensed to print to novaPDF printer (http://www.novapdf.com)