Title: Stream Organisms
1Stream Organisms
2Objectives
- 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.
3Stream organisms
- The slides on stream organisms are divided into
three sections - Autotrophs
- Invertebrates
- Fish
4Autotrophs
- 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.
www.glifwc.org/
5Benthic 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)
6Periphyton
- 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.
7Periphyton components
- Lotic phytoplankton include
- Algae
- Protozoans
- Cyanobacteria
- These are small enough to remain suspended in the
water column and be transported by currents.
Biodidac
Hoffman Image Gallery
Hoffman Image Gallery
8Attached 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.
Hoffman Image Gallery
Hoffman Image Gallery
University of Wisconsin Botanical Images
Collection
9Seasonal 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
10Distribution of autotrophs Lakes vs rivers
11Algal primary productivity
12Macrophytes
- 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.
13Macrophyte 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)
14Macrophyte growth forms
- 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.
15Basic 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).
16Patchy distribution of macrophytes
- Macrophyte distribution and abundance changes
annually
www.glifwc.org/
17Macrophyte 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//images.fws.gov/
www.epa.gov/25water/exotic/slide15.jpg
http//www.fcsc.usgs.gov/posters/Nonindigenous/Non
indigenous_Crustaceans/nonindigenous_crustaceans.h
tml
18Stream 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
19Insects
- Adaptation to life in streams and rivers
- Introduction to taxonomy
- General life cycle
- Introduction to functional roles
20Morphological adaptations to running water
Adaptation Significance Representative Groups and Structures Comments
Dorsoventrally Flat Allows crawling in slow current boundary layer on substrate Odonata Gomphidae Trichoptera - Glossosoma
Streamlining Fusiform body minimizes resistance to current Ephemeroptera Baetis Diptera - 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
21Morphological 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 Simulium Trichoptera - 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
22Classification 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
23Aquatic 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
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24Aquatic insect orders
Order Number of North American aquatic species (estimated) Larvae Adults
Diptera (flies and midges) 4662
Hemiptera (true bugs) 410
Coleoptera (beetles) 1842
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25Aquatic insect orders
Order Number of North American aquatic species (estimated) Larvae Adults
Megaloptera (alderflies and dobsonflies) 43
Neuroptera (spongilla flies) 6
Lepidoptera (moths) 635
Hymenoptera (parasitic wasps) 55
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26Life cycles of aquatic Insects
Holometabolous
Hemimetabolous
- Holometabolous insects pass through a complete
metamorphosis that consists of four stages - 1) Egg gt immature (larva) gt Pupa gt Adult
- 2) During pupal stage adult characteristics
develop - 3) Examples include caddisflies and dipterans
such as blackflies
fig. 14.2, p. 179 from Allan and Cushing
27Life cycles of aquatic Insects
Holometabolous
Hemimetabolous
- Hemimetabolous insects pass through three stages
in their life cycle - 1) Egg gt Immature (nymph) gt Adult
- 2) Adults are terrestrial
- 3) Examples include stoneflies, mayflies, and
dragonflies
fig. 14.2, p. 179 from Allan and Cushing
28Hemimetabolous life cycle
www.usask.ca/biology/skabugs/lifecycle/insectlifec
ycle.html
29Holometabolous life cycle
- Complete metamorphosis in the caddisfly
Hydropsyche sp. - Larva
- Pupa
- Adult
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ycle.html
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ycle.html
Adult
www.usask.ca/biology/skabugs/lifecycle/insectlifec
ycle.html
30Life 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).
31Ecological roles
- Macroinvertebrates play a variety of roles in
food webs.
Fig. 4.9, p.53 in Allan and Cushing, 2001
32Macroinvertebrate 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)
33Macroinvertebrate functional roles
- 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
34Macroinvertebrate 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
35Macroinvertebrate functional roles
- 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)
36Other macroinvertebrates
Annelids (leeches and aquatic worms)
Molluscs (clams, mussels, and snails)
Crustaceans (crayfish, amphipods, and mites)
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