Stream Organisms Uni1: Module 4, Lecture 4. Developed by: Merrick, Richards Updated: August 2003 U1-m4-s2 Objectives Students will be able to: describe

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.


The slides on stream organisms are divided into three sections: Autotrophs Invertebrates Fish

Stream organisms

Developed by: Merrick, Richards Updated: August 2003 U1-m4-s4www.glifwc.org/

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.


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)


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.

www.duluthstreams.org/understanding/algae.html


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

www.cawthron.org.nz/periphyton_image.htm


University of Wisconsin Botanical Images Collection



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)


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

www.urbanrivers.org/web_images/diatoms.gif


Distribution of autotrophs: Lakes vs rivers

Image from Allan, Fig. 4.12, p. 105


Algal primary productivity

Photosynthesis-Light - Temperature-Nutrient - Chronic toxicity-Velocity

Respiration/Excretion

Grazing

Mortality

-Acute toxicity

-High temperature

Sinking

- Velocity

- Stress

Algal biomassWashout-Velocity-Available substrate

Loading Turbulent diffusion

www.epa.gov/waterscience/pc/wqnews/algal.gif


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.


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

www.sthubertsisle.com/Lily%20pads.jpg

Free-floating

http://lakes.chebucto.org/VIEW/PIC/duckweed.jpg

Submerged

http://riverwoods.ces.fau.edu/riverwoods/display.ihtml?pic=../photos/birdseyenupharsm.jpg


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


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


www.glifwc.org/

Patchy distribution of macrophytes

Macrophyte distribution and abundance changes annually


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.

http://www.fcsc.usgs.gov/posters/Nonindigenous/Nonindigenous_Crustaceans/nonindigenous_crustaceans.html

http://images.fws.gov/www.epa.gov/25water/exotic/slide15.jpg


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


Insects

Adaptation to life in streams and rivers

Introduction to taxonomy

General life cycle Introduction to

functional roles


Morphological adaptations to running water

Adaptation Significance Representative Groups and Structures

Comments

Dorsoventrally Flat

Allows crawling in slow current boundary layer on substrate

Odonata – GomphidaeTrichoptera - Glossosoma

Streamlining Fusiform body minimizes resistance to current

Ephemeroptera – BaetisDiptera - Simulium

Relatively rare body form

Reduced projecting structures

Reduces resistance to current

Ephemeroptera - Baetis Large lateral structures exist in some groups

Suckers Attach to smooth surfaces

Diptera - Blephariceridae Rare adaptation

Friction Pads Increased contact reduces chances of being dislodged

Coleoptera - Psephinus


Morphological adaptations to running water

Adaptation Significance Representative Groups and Structures

Comments

Small size Allows 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 – SimuliumTrichoptera - Hydropsychidae

Ballast Cases made of large stones Trichoptera - Goera

Attachment claws /dorsal processes

Stout claws aid in attachment to plants

Ephemeroptera - Ephemerella

Reduced power of flight

Prevents emigration from small habitats

Plecoptera - Allocapnia Reduces dispersal ability

Hairy bodies Keeps sand/soil particles away while burrowing

Ephemeroptera - Hexagenia Allows water flow over body

Hooks or Grapples

Attachment to rough areas of substrates

Coleoptera - Elmidae


Classification of insects

Common Name

Human Canada Goose Lake Darner Dragonfly Giant water bug

Kingdom Animalia Animalia Animalia Animalia

Phylum Chordata Chordata Arthropoda Arthropoda

Class Mammalia Aves Insecta Insecta

Order Primate Anseriformes Odonata Hemiptera

Family Hominidae Anatidae Aeshnidae Belostomatidae

Genus Homo Branta Aeshna Lethocerus

species sapiens canadensis eremita americanus

Author Scudder (Leidy)www.usask.ca/biology/skabugs/idclass/classify.html


Aquatic insect orders

Order

Number of North American aquatic species

(estimated)

Larvae Adults

Ephemeroptera (mayflies) 572

Odonata (dragonflies and damselflies)

357

Plecoptera (stoneflies)

582

Trichoptera (caddisflies) 1215+

www.usask.ca/biology/skabugs/






www.usask.ca/biology/skabugs/ www.usask.ca/biology/skabugs/



Order


(estimated)

Larvae Adults

Diptera (flies and midges)

4662+

Hemiptera (true bugs)

410

Coleoptera (beetles)

1842+www.usask.ca/biology/skabugs/










Order


(estimated)

Larvae Adults

Megaloptera (alderflies and dobsonflies)

43

Neuroptera (spongilla flies)

6

Lepidoptera (moths)

635

Hymenoptera (parasitic wasps) 55







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


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


www.usask.ca/biology/skabugs/lifecycle/insectlifecycle.html

Hemimetabolous life cycle


Adult

Holometabolous life cycle

Complete metamorphosis in the caddisfly Hydropsyche sp. Larva Pupa Adult





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).

www.mendozaflyshop.com/images/6_01.jpg


Ecological roles

Macroinvertebrates play a variety of roles in food webs.

Fig. 4.9, p.53 in Allan and Cushing, 2001


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

www.oaa.pdx.edu/CAE/Programs/sti/pratt/feeding/inverts/shredder.html


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

www.oaa.pdx.edu/CAE/Programs/sti/pratt/feeding/inverts/collector.html


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

www.oaa.pdx.edu/CAE/Programs/sti/pratt/feeding/inverts/scraper.html


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

www.oaa.pdx.edu/CAE/Programs/sti/pratt/feeding/inverts/predator.html


Other macroinvertebrates

Annelids (leeches and aquatic worms)

Molluscs (clams, mussels, and snails)

Crustaceans (crayfish, amphipods, and mites)

http://www.usask.ca/biology/skabugs/

http://www.usask.ca/biology/skabugs/ http://www.usask.ca/biology/skabugs/

http://www.usask.ca/biology/skabugs/

http://www.usask.ca/biology/skabugs/ http://www.usask.ca/biology/skabugs/ http://www.usask.ca/biology/skabugs/

Documents

Stream Organisms Uni1: Module 4, Lecture 4. Developed by: Merrick, Richards Updated: August 2003 U1-m4-s2 Objectives Students will be able to: describe