Stream Organisms Uni1: Module 4, Lecture 4

Developed by: Merrick, Richards Updated: August 2003 U1-m4-s2 Objectives Students will be able to:  describe major characteristics of autotrophs.  categorize autotrophs types by location.  contrast seasonal variations in the growth of periphyton communities.  compare and contrast the four types of macrophytes.  define and provide examples of stream macroinvertebrates.  provide examples of morphological adaptations to water and interpret their significance.  diagram the life cycles of aquatic insects.  compare and contrast the functional roles of macroinvertebrates in organic matter processing.

Developed by: Merrick, Richards Updated: August 2003 U1-m4-s3  The slides on stream organisms are divided into three sections:  Autotrophs  Invertebrates  Fish Stream organisms

Developed by: Merrick, Richards Updated: August 2003 U1-m4-s4 Autotrophs  Autotrophs are organisms that acquire materials from the environment and energy from sunlight in the process of producing organic matter.  Green plants, diatoms and filamentous algae, some bacteria, and some protists make up the autotrophs in lotic systems.  In contrast, heterotrophs, such as fungi or fish gain nutrients and energy by processing dead organic matter.  Functionally, autotrophs serve lotic communities by making organic energy available to consumer organisms at higher trophic levels.

Developed by: Merrick, Richards Updated: August 2003 U1-m4-s5 Benthic autotrophs  Benthic autotrophs grow on virtually all surfaces receiving light in flowing waters and are collectively referred to as the periphyton community.  Habitat specialization allows for classification of benthic autotrophs into groups;  Species that grow on stones (epilithon)  Species that grow on soft sediments (epipelon)  Species that grow on other plants (epiphyton)

Developed by: Merrick, Richards Updated: August 2003 U1-m4-s6 Periphyton  Periphyton is a complex matrix of algae and heterotrophic microbes attached to submerged substrata in almost all aquatic ecosystems.  It serves as an important food source for invertebrates and some fish, and it can be an important sorber of contaminants.

Developed by: Merrick, Richards Updated: August 2003 U1-m4-s7 Hoffman Image Gallery Periphyton components  Lotic phytoplankton include:  Algae  Protozoans  Cyanobacteria  These are small enough to remain suspended in the water column and be transported by currents. phytoflagellates (euglenophyta) Biodidac

Developed by: Merrick, Richards Updated: August 2003 U1-m4-s8 University of Wisconsin Botanical Images Collection Hoffman Image Gallery Attached and benthic populations  Many blue-green algae grow attached on the surface of rocks and stones (epilithic forms), on submerged plants (epiphytic forms) or on the bottom sediments (epipelic forms, or the benthos) of rivers.  The epiphytic flora of lotic communities is usually dominated by diatoms and green algae, and blue-greens are of less importance in this community. blue-green algae (cyanobacteria) Diatoms Biodidac green algae (chlorophyta)

Developed by: Merrick, Richards Updated: August 2003 U1-m4-s9 Seasonal succession in periphyton communities  Diatoms dominate during the winter, spring, and early summer  Green algae and cyanobacteria populations increase during the summer  Benthic autotrophs tends to decrease during the summer as a result of increased shading, increasing again in fall

Developed by: Merrick, Richards Updated: August 2003 U1-m4-s10 Distribution of autotrophs: Lakes vs rivers Image from Allan, Fig. 4.12, p. 105

Developed by: Merrick, Richards Updated: August 2003 U1-m4-s11 Algal primary productivity Photosynthesis -Light- Temperature -Nutrient- Chronic toxicity -Velocity Respiration/Excretion Grazing Mortality -Acute toxicity -High temperature Sinking - Velocity - Stress Algal biomass Washout -Velocity -Available substrate Loading Turbulent diffusion

Developed by: Merrick, Richards Updated: August 2003 U1-m4-s12 Macrophytes  Westlake (1975a) identified four primary growth forms:  1) Emergents occurring on river banks and shoals typically are rooted in soil that is near or below the waterline and have aerial leaves and reproductive structures;  2) Floating-leaved species occupy margins of slow current areas, are rooted in submerged soils, and have aerial or floating leaves and reproductive structures;  3) Free-floating species are typically not attached to the substrate and often form mats that entangle other species in slow flowing tropical rivers;  4) Submerged species are rooted to the substrate, have submerged leaves, and are located in mid-channel to the point of insufficient light penetration.

Developed by: Merrick, Richards Updated: August 2003 U1-m4-s13 Macrophyte growth forms  Emergents: banks and shoals  Floating-leaved: stream margins  Free-floating: slow (tropical) rivers  Submerged: midstream (limited by light penetration, current speed, and substrate type) Emergent cce.cornell.edu/onondaga/watersheds/images/milfoil.jpg Floating-leaved Free-floating Submerged

Developed by: Merrick, Richards Updated: August 2003 U1-m4-s14  Aquatic macrophytes do not show adaptations to life in rivers and streams.  Consequently, they are limited to areas of little current and suitable substrate.  Most commonly these areas include; deltas, backwaters, pools, beaver impoundments, margins, banks, shoals, and contiguous wetlands. Macrophyte growth forms

Developed by: Merrick, Richards Updated: August 2003 U1-m4-s15 Basic macrophyte structure  Success and maintenance of macrophyte populations in significant current can be attributed to a few adaptive characteristics.  Tough, flexible stems and leaves; attachment by adventitious roots, rhizomes, or stolons; and vegetative reproduction characterize most lotic macrophyte species (Hynes, 1970; Westlake, 1975a). aquat1.ifas.ufl.edu/zizaqu2.jpg Stems and leaves Adventitious roots

Developed by: Merrick, Richards Updated: August 2003 U1-m4-s16 Patchy distribution of macrophytes  Macrophyte distribution and abundance changes annually

Developed by: Merrick, Richards Updated: August 2003 U1-m4-s17 Macrophyte consumers  Even in streams that show high macrophyte productivity, a relatively small fraction of the streams total energy results from macrophyte production.  The fate of this primary production includes herbivory, secretion of dissolved organic matter, and decomposition.  Herbivory is carried out in large part by vertebrates, including waterfowl, manatee, grass carp, muskrat (Westlake, 1975b), and moose

Developed by: Merrick, Richards Updated: August 2003 U1-m4-s18 Stream invertebrates  Much of the aquatic life in streams is composed of benthic macroinvertebrates.  The term macroinvertebrate includes clams, crayfish, worms, and insects.  Macroinvertebrates do not have internal skeletons, are larger than 5 microns, and, typically, live on a stream substrate (bottom, woody debris, macrophyte, etc..) photo source: North American Benthological Society

Developed by: Merrick, Richards Updated: August 2003 U1-m4-s19 Insects  Adaptation to life in streams and rivers  Introduction to taxonomy  General life cycle  Introduction to functional roles

Developed by: Merrick, Richards Updated: August 2003 U1-m4-s20 Morphological adaptations to running water AdaptationSignificanceRepresentative Groups and Structures Comments Dorsoventrally Flat Allows crawling in slow current boundary layer on substrate Odonata – Gomphidae Trichoptera - Glossosoma StreamliningFusiform body minimizes resistance to current Ephemeroptera – Baetis Diptera - Simulium Relatively rare body form Reduced projecting structures Reduces resistance to current Ephemeroptera - BaetisLarge lateral structures exist in some groups SuckersAttach to smooth surfaces Diptera - BlephariceridaeRare adaptation Friction PadsIncreased contact reduces chances of being dislodged Coleoptera - Psephinus

Developed by: Merrick, Richards Updated: August 2003 U1-m4-s21 Morphological adaptations to running water AdaptationSignificanceRepresentative Groups and Structures Comments Small sizeAllows use of slow-current boundary layer on top of substrate Stream animals are smaller than stillwater relatives Silk and sticky secretions Attachment to stones in swift current Diptera – Simulium Trichoptera - Hydropsychidae BallastCases made of large stonesTrichoptera - Goera Attachment claws /dorsal processes Stout claws aid in attachment to plants Ephemeroptera - Ephemerella Reduced power of flight Prevents emigration from small habitats Plecoptera - AllocapniaReduces dispersal ability Hairy bodiesKeeps sand/soil particles away while burrowing Ephemeroptera - HexageniaAllows water flow over body Hooks or Grapples Attachment to rough areas of substrates Coleoptera - Elmidae

Developed by: Merrick, Richards Updated: August 2003 U1-m4-s22 Classification of insects Common Name HumanCanada GooseLake Darner DragonflyGiant water bug KingdomAnimalia PhylumChordata Arthropoda ClassMammaliaAvesInsecta OrderPrimateAnseriformesOdonataHemiptera FamilyHominidaeAnatidaeAeshnidaeBelostomatidae GenusHomoBrantaAeshnaLethocerus speciessapienscanadensiseremitaamericanus AuthorScudder(Leidy)

Developed by: Merrick, Richards Updated: August 2003 U1-m4-s23 Aquatic insect orders Order Number of North American aquatic species (estimated) LarvaeAdults Ephemeroptera (mayflies) 572 Odonata (dragonflies and damselflies) 357 Plecoptera (stoneflies) 582 Trichoptera (caddisflies)

Developed by: Merrick, Richards Updated: August 2003 U1-m4-s24 Aquatic insect orders Order Number of North American aquatic species (estimated) LarvaeAdults Diptera (flies and midges) Hemiptera (true bugs) 410 Coleoptera (beetles)

Developed by: Merrick, Richards Updated: August 2003 U1-m4-s25 Aquatic insect orders Order Number of North American aquatic species (estimated) LarvaeAdults Megaloptera (alderflies and dobsonflies) 43 Neuroptera (spongilla flies) 6 Lepidoptera (moths) 635 Hymenoptera (parasitic wasps) 55

Developed by: Merrick, Richards Updated: August 2003 U1-m4-s26 Life cycles of aquatic Insects  Holometabolous insects pass through a complete metamorphosis that consists of four stages:  1) Egg > immature (larva) > Pupa > Adult  2) During pupal stage adult characteristics develop  3) Examples include; caddisflies and dipterans such as blackflies Holometabolous Hemimetabolous fig. 14.2, p. 179 from Allan and Cushing

Developed by: Merrick, Richards Updated: August 2003 U1-m4-s27 Life cycles of aquatic Insects  Hemimetabolous insects pass through three stages in their life cycle:  1) Egg > Immature (nymph) > Adult  2) Adults are terrestrial  3) Examples include; stoneflies, mayflies, and dragonflies Holometabolous Hemimetabolous fig. 14.2, p. 179 from Allan and Cushing

Developed by: Merrick, Richards Updated: August 2003 U1-m4-s28 Hemimetabolous life cycle

Developed by: Merrick, Richards Updated: August 2003 U1-m4-s29 Adult Holometabolous life cycle  Complete metamorphosis in the caddisfly Hydropsyche sp.  Larva  Pupa  Adult

Developed by: Merrick, Richards Updated: August 2003 U1-m4-s30 Life cycle length  Multivoltine – several generations per year  Univoltine – one generation per year  Semivoltine – one generation every 2-3 years  Baetis sp., a common mayfly is noted to be univoltine at low elevation and warmer temperatures and semivoltine at high elevations and colder temperatures (Allan, 1995).

Developed by: Merrick, Richards Updated: August 2003 U1-m4-s31 Ecological roles  Macroinvertebrates play a variety of roles in food webs. Fig. 4.9, p.53 in Allan and Cushing, 2001

Developed by: Merrick, Richards Updated: August 2003 U1-m4-s32  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) Macroinvertebrate functional roles in organic matter processing A caddisfly of the family Limnephilidae

Developed by: Merrick, Richards Updated: August 2003 U1-m4-s33  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 Macroinvertebrate functional roles A blackfly of the family Simulidae A caddisfly of the family Hydroptilidae

Developed by: Merrick, Richards Updated: August 2003 U1-m4-s34  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 Macroinvertebrate functional roles A dipteran of the family Thaumaleidae

Developed by: Merrick, Richards Updated: August 2003 U1-m4-s35  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) Macroinvertebrate functional roles A stonefly of the family Perlidae A “true bug” of the family Notonectidae

Developed by: Merrick, Richards Updated: August 2003 U1-m4-s36 Other macroinvertebrates Annelids (leeches and aquatic worms) Molluscs (clams, mussels, and snails) Crustaceans (crayfish, amphipods, and mites)