Faunal Diversity

FISH 7380

Dr. e. irwin

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"

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)"

Food webs

Microbes

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

DOM

Meiofauna pass through 500 micron, retained 40 micron

sieve 58-82% of species in streams Rotifers (Bdelloidae=benthic 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

Meiofauna

Macroinvertebrates > 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

Diptera

Coleoptera

Tricoptera

Hemiptera

Lepidoptera

Megaloptera

Odonata

Plecoptera

Decapoda

Fat pocketbook- Potamilus capax

GastropodaBivalvia

Interrupted rocksnail Leptotoxis formeani

“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.

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 Africa2000 spp North America (& Mexico) 1100 spp Europe 250 spp Australia 230 spp Alabama 328 spp

Floodplain rivers are diverse

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

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)

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).

Sabretooth salmon (3 mya)

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

Western Rivers Small fishes rule, except out west

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.

Imperilment