Ecosystem Processes and the River Continuum Concept Unit

Ecosystem Processes and the River Continuum Concept Unit 1: Module 4, Lecture 5

Objectives Students will be able to: · classify sources of organic matter. · diagram the flow of instream organic matter. · factors that influence the storage of organic matter in streams. · explain the river continuum concept · compare and contrast low order, mid-order, and high order streams. Developed by: Merrick, Richards Updated: August 2003 U 1 -m 4 -s 2

General organic matter pathway geography. uoregon. edu /. . . /SCRfig 2 -33 web. jpg Developed by: Merrick, Richards Updated: August 2003 U 1 -m 4 -s 3

Sources of organic matter · Autochthonous – instream · Allochthonous – out of stream www. landcare. org. nz/SHMAK/ manual/6 doing. htm 140. 211. 62. 101/streamwatch/ swm 10. html Developed by: Merrick, Richards www. bbg. org/sci/blackrock/ veg/brfredmaple. html Updated: August 2003 U 1 -m 4 -s 4

Types of organic matter · Dissolved organic matter · Soluble organic compounds that leach from leaves, roots, decaying organisms, and other sources · Largest pool of organic matter in streams Developed by: Merrick, Richards · Particulate organic matter · Coarse particulate organic matter · Woody material & leaves > 1 mm · Fine particulate organic matter · Leaf fragments, invertebrate feces, and organic precipitates < 1 mm Updated: August 2003 U 1 -m 4 -s 5

Instream organic matter processing · This figure depicts the routes carbon follows as it is processed within a stream. · Microbes, macroinvertebrates, fish, and other organisms all play roles in the physical and chemical processing of organic matter. Developed by: Merrick, Richards Updated: August 2003 The River Continuum - www. oaa. pdx. edu/CAE/Programs/ sti/pratt/energy. html U 1 -m 4 -s 6

Macroinvertebrate functional roles in organic matter processing · Shredders · Dominant food · Vascular macrophyte tissue · Coarse particulate organic material (CPOM) · Wood · Feeding mechanisms · Herbivores - Chew and mine live macrophytes · Detritivores - Chew on CPOM · Representatives · Scathophagidae (dung flies) · Tipulidae (crane flies) Developed by: Merrick, Richards A caddisfly of the family Limnephilidae Updated: August 2003 U 1 -m 4 -s 7

Macroinvertebrate functional roles · Collectors · Dominant food · Decompose fine particulate organic matter (FPOM) · Feeding mechanisms · Filterers - Detritivores · Gatherers - Detritivores · Representatives · Filterers A blackfly of the family Simulidae • Hydropsychidae • Simulidae (black flies) · Gatherers • • • Elmidae (riffle beetles) Chironomini Baetis Ephemerella Hexagenia Developed by: Merrick, Richards A caddisfly of the family Hydroptilidae Updated: August 2003 U 1 -m 4 -s 8

Macroinvertebrate functional roles · Scrapers · Dominant food · Periphyton (attached algae) · Material associated with periphyton · Feeding mechanisms · Graze and scrape mineral and organic surfaces · Representatives · Helicopsychidae · Psephenidae (water pennies) · Thaumaleidae (solitary midges) · Glossosoma · Heptagenia Developed by: Merrick, Richards A dipteran of the family Thaumaleidae Updated: August 2003 U 1 -m 4 -s 9

Macroinvertebrate functional roles · Predators · Dominant food · Living animal tissue · Feeding mechanisms · Engulfers - Attack prey and ingest whole animals · Piercers - Pierce tissues, suck fluids A stonefly of the family Perlidae · Representatives · Engulfers • Anisoptera (dragonflies) • Acroneuria • Corydalus (hellgrammites) · Piercers • Veliidae (water striders) • Corixidae (water boatmen) • Tabanidae (deerflies & horseflies) Developed by: Merrick, Richards A “true bug” of the family Notonectidae Updated: August 2003 U 1 -m 4 -s 10

Seasonal variation in particulate organic carbon · Low concentrations in winter and fall Developed by: Merrick, Richards · High concentrations in summer Updated: August 2003 Photos by g. merrick U 1 -m 4 -s 11

Fate of organic matter · Organic matter that enters streams may be (percent estimates are approximate and variable): · Stored within the stream bank or channel (25%) · Exported downstream (50%) · Metabolized and respired as carbon dioxide by organisms (25%) Photo – g. merrick Developed by: Merrick, Richards Updated: August 2003 U 1 -m 4 -s 12

Storage of organic matter · Factors that are likely to increase retention time are debris dams, beaver dams, floodplains, and geomorphological features of the stream or river that impede flow. Developed by: Merrick, Richards Updated: August 2003 U 1 -m 4 -s 13

Net primary production versus litter fall Stream Autotochthonous Allochthonous Bear Brook, NH 0. 6 g C/m 2/year 251 g C/m 2/year Silver Springs, FL 981 g C/m 2/year 54 g C/m 2/year Developed by: Merrick, Richards Updated: August 2003 U 1 -m 4 -s 14

Bear Brook, New Hampshire · Bear Brook in New Hampshire is the site of a famous organic matter budget study (Likens, 1973). · In the this small, forested headwater stream it was found that greater than 99% of the carbon input to Bear Brook came from allochthonous sources (POM slightly greater than DOM). · Close to 65% of this input was exported downstream from the 1700 meter long study site. Developed by: Merrick, Richards · Input of DOM exceeded exports · Due to leaf fall more POM was exported than entered the site Updated: August 2003 U 1 -m 4 -s 15

The River Continuum Concept Developed by: Merrick, Richards Updated: August 2003 U 1 -m 4 -s 16

Stream order and the RCC · Low order streams · Shaded headwater streams · Coarse particulate matter (CPOM) provides resource base for consumer community Developed by: Merrick, Richards Updated: August 2003 U 1 -m 4 -s 17

Stream order and the RCC · Mid-order streams · Energy inputs change as stream broadens · Shading and contribution of CPOM decreases · Sunlight supports significant periphyton production · Upstream processing of CPOM results in input of fine particulate matter (FPOM) Developed by: Merrick, Richards Updated: August 2003 U 1 -m 4 -s 18

Stream order and the RCC · High order streams · As streams widen even more and flows drop, macrophytes become more abundant · In the largest rivers, macrophytes are limited to the river margins because mid-channel conditions are typically too turbid · Bottom substrate becomes smaller Developed by: Merrick, Richards Updated: August 2003 U 1 -m 4 -s 19

Carbon fluxes in a stream ecosystem Figure 12. 1 Developed by: Merrick, Richards Updated: August 2003 U 1 -m 4 -s 20