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

Developed by: Merrick, Richards Updated: August 2003 U1-m4-s2 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 U1-m4-s3 geography.uoregon.edu/.../SCRfig2-33web.jpg General organic matter pathway

Developed by: Merrick, Richards Updated: August 2003 U1-m4-s4 Sources of organic matter  Autochthonous – instream  Allochthonous – out of stream /streamwatch/ swm10.html manual/6doing.htm veg/brfredmaple.html

Developed by: Merrick, Richards Updated: August 2003 U1-m4-s5 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  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

Developed by: Merrick, Richards Updated: August 2003 U1-m4-s6 The River Continuum - sti/pratt/energy.htmlwww.oaa.pdx.edu/CAE/Programs/ sti/pratt/energy.html Instream organic matter processing  This figure depicts the routes carbon follows as it is processed within a stream.  Microbes, macro- invertebrates, fish, and other organisms all play roles in the physical and chemical processing of organic matter.

Developed by: Merrick, Richards Updated: August 2003 U1-m4-s7  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) A caddisfly of the family Limnephilidae Macroinvertebrate functional roles in organic matter processing

Developed by: Merrick, Richards Updated: August 2003 U1-m4-s8  Collectors  Dominant food  Decompose fine particulate organic matter (FPOM)  Feeding mechanisms  Filterers - Detritivores  Gatherers - Detritivores  Representatives  Filterers Hydropsychidae Simulidae (black flies)  Gatherers Elmidae (riffle beetles) Chironomini Baetis Ephemerella Hexagenia A blackfly of the family Simulidae A caddisfly of the family Hydroptilidae Macroinvertebrate functional roles

Developed by: Merrick, Richards Updated: August 2003 U1-m4-s9  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 A dipteran of the family Thaumaleidae Macroinvertebrate functional roles

Developed by: Merrick, Richards Updated: August 2003 U1-m4-s10  Predators  Dominant food  Living animal tissue  Feeding mechanisms  Engulfers - Attack prey and ingest whole animals  Piercers - Pierce tissues, suck fluids  Representatives  Engulfers Anisoptera (dragonflies) Acroneuria Corydalus (hellgrammites)  Piercers Veliidae (water striders) Corixidae (water boatmen) Tabanidae (deerflies & horseflies) A stonefly of the family Perlidae A “true bug” of the family Notonectidae Macroinvertebrate functional roles

Developed by: Merrick, Richards Updated: August 2003 U1-m4-s11  Low concentrations in winter and fall  High concentrations in summer Photos by g. merrick Seasonal variation in particulate organic carbon

Developed by: Merrick, Richards Updated: August 2003 U1-m4-s12  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 Fate of organic matter

Developed by: Merrick, Richards Updated: August 2003 U1-m4-s13  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. Storage of organic matter

Developed by: Merrick, Richards Updated: August 2003 U1-m4-s14 Net primary production versus litter fall StreamAutotochthonousAllochthonous Bear Brook, NH 0.6 g C/m2/year251 g C/m2/year Silver Springs, FL 981 g C/m2/year54 g C/m2/year

Developed by: Merrick, Richards Updated: August 2003 U1-m4-s15 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.  Input of DOM exceeded exports  Due to leaf fall more POM was exported than entered the site

Developed by: Merrick, Richards Updated: August 2003 U1-m4-s16 The River Continuum Concept

Developed by: Merrick, Richards Updated: August 2003 U1-m4-s17 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 U1-m4-s18 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 U1-m4-s19 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 U1-m4-s20 Carbon fluxes in a stream ecosystem Figure 12.1