Faunal Diversity

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Faunal Diversity

• FISH 7380
• Dr. e. irwin

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Objectives

• Understand the basic structure of riverine
  communities
• Learn broad patterns of faunal diversity across
  N.AM. river systems
• Understand mechanisms contributing to and
  underlying differences in species richness among
  river systems
• Know the big five, and other especially diverse
  N.AM. fish families
• Wrestle with "ecological consequences of
  diversity"

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Riverine communities webs of the really
well-known (fishes) and the totally undescribed
(fungi bacteria)

• Functional Groups
• Heterotrophy vs. Autotrophy
• Food webs
• Diversity "the variety and variability among
  living organisms and the ecological complexes in
  which they occur (Office of Technology Assessment
  1987)"

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Food webs
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Microbes

• Bacteria, protists and fungi-
• decomposers of POM, retain and transform DOM

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Meiofauna

• pass through 500 micron, retained 40 micron sieve
• 58-82 of species in streams
• Rotifers (Bdelloidaebenthic group 2,500 species
  30 planktonic)
• Gastrotrichs (Chaetonotida (mainly FW 350
  species)
• e.g. rotifers, harpaticoids, cyclopoid copepods,
  flatworms. gastrotrichs, young insects.
• Interstitial, burrowing, epibenthic

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Meiofauna
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Macroinvertebrates

• gt 15,000 aquatic invertebrates described,
  including
• 4665 Diptera
• 1640 Coleoptera
• 1340 Trichoptera ("The queen order of insects")
• 400 Hemiptera
• 50 Megaloptera
• 635 Lepidoptera (aquatic!)
• 575 Ephemeroptera
• 550 Plecoptera
• 415 Odonates - 170 in AL (Krotzer abstract)
• 386 Crayfishes - 70 in AL (Johnson thesis)
• 500 Gastropoda
• 320 Bivalva

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Diptera
Coleoptera
Tricoptera
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Hemiptera
Megaloptera
Lepidoptera
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Odonata
Plecoptera
Decapoda
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Bivalvia
Gastropoda
Fat pocketbook- Potamilus capax
Interrupted rocksnail Leptotoxis formeani
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• New species are described annually, and a total
  head count never will be complete (Williams and
  Neves 1992)
• "The conditions for speciation of stream dwelling
  animals has been nearly ideal in eastern North
  America for many million years. One of the
  results has been the origin of what is probably
  the richest freshwater mollusk fauna in the
  world." David H. Stansbery, 1970.

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Fishes

• About 800 spp in North America, excluding Mexico,
  mostly riverine
• compared to (best available underestimates!)
• about 10250 freshwater spp worldwide
• South America 2800 spp
• Africa 2000 spp
• North America ( Mexico) 1100 spp
• Europe 250 spp
• Australia 230 spp
• Alabama 328 spp

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Floodplain rivers are diverse
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Patterns of diversity of fishes in North America
Why?

• The mighty Mississippi, the southeast, and the
  west
• Ecological stability geographic instability
  spp diversity
• Drainages are not equally blessed

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NA drainages

• Mississippi-Missouri-Ohio richest, 375 spp, 31
  families
• SE Province Atl and Gulf Slope drainages,
  Savannah R to Ponchartrain, 268 spp, 31 families
• Western systems fewer spp, but high endemism.
  Why impt from a management perspective?
• e.g., Colorado River Basin 32 spp, 7 families -
  69 spp endemic (22)

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NA fishes

• N. Am. fishes a relatively young fauna
• 60 Miocene or younger (about 26-23 mya)
• (Miller, cited in Hocutt and Wiley, p 443).

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Sabretooth salmon (3 mya)
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The big five

• Nearly 80 comprise 5 families -
• Cyprinidae 302 spp
• (largest family of fishes 1600 spp worldwide)
• Percidae 165 spp
• This number is already out of date!)
• Catostomidae 70 spp
• (This one is, too!)
• Ictaluridae 48 spp
• (endemic to N Am 27 spp are madtoms)
• Centrarchidae 32 spp

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Western Rivers

• Small fishes rule, except out west

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Stability-diversity
N. M. Burkhead, S. J. Walsh, B. J. Freeman and J.
D. Williams, 1997. Status and restoration of the
Etowah River, an imperiled southern Appalachian
ecosystem. In Aquatic Fauna in Peril The
Southeastern Perspective, G. W. Benz and D. E.
Collins, eds.
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Imperilment