instructor lecture 5
TRANSCRIPT
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Diversity of Aquatic OrganismsVertebrates and Plants
1. How are fish classified?
2. Why are planktivores size-selective?
3. How many mating types are there in bluegill?
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What is a fish?
Phylum Chordata, Subphylum Vertebrata
Lives in water
Possess gills that are used throughout life
Has fins
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Major Classes of Living Freshwater Fishes
Jawless fishes lamprey
Sharks and Rays some rays live in tropical rivers
Class Agnatha
(Cephalaspidomorphi)
Class Chondrichthyes
Potamotrygon
www.tcp-ip.or.jp/~y-miura/ fws/Esyurui.html
Lampetra richardsoni
(western brook lamprey)www.orst.edu/instruct/fw316/ markle/fishimages.html
http://www.tcp-ip.or.jp/~y-miura/fws/Esyurui.htmlhttp://www.orst.edu/instruct/fw316/markle/fishimages.htmlhttp://www.orst.edu/instruct/fw316/markle/fishimages.htmlhttp://www.tcp-ip.or.jp/~y-miura/fws/Esyurui.htmlhttp://www.tcp-ip.or.jp/~y-miura/fws/Esyurui.htmlhttp://www.tcp-ip.or.jp/~y-miura/fws/Esyurui.htmlhttp://www.tcp-ip.or.jp/~y-miura/fws/Esyurui.htmlhttp://www.tcp-ip.or.jp/~y-miura/fws/Esyurui.html -
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Major Groups of Living Freshwater Fishes
2 classes of Bony Fishes (Osteichthyes)
Class Sarcopterygii lungfishes
Class Actinopterygii ray-fins
Lepidosiren
(South American Lungfish)
http://www.ucmp.berkeley.edu/vertebrates/sarco/dipnoi.html
Perca flavescens
(Yellow Perch)
www.cnr.vt.edu/efish/ families/yperch.html
http://www.cnr.vt.edu/efish/families/yperch.htmlhttp://www.cnr.vt.edu/efish/families/yperch.htmlhttp://www.ucmp.berkeley.edu/vertebrates/sarco/lungfish1.jpg -
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Spiny rayed fish vs. soft rayed fish
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Order Perciformes
Contains over 9,200 species
Largest order of vertebrates
Very diverse group, but most are
predators
Sunfish
Bass
Yellow Perch
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East African Cichlids
www.reshafim.org.il/fishfarm/ lake_victoria.htm
Haplochromis obliquidens
badmanstropicalfish.com/ afcichlids.html
Over 300 endemic
species describedfrom Lake Victoria,
500 from Lake Malawi
and 160 from Lake
Tanganyika
(Order Perciformes)
http://www.reshafim.org.il/fishfarm/lake_victoria.htmhttp://badmanstropicalfish.com/afcichlids.htmlhttp://badmanstropicalfish.com/afcichlids.htmlhttp://www.reshafim.org.il/fishfarm/lake_victoria.htm -
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Order Cypriniformes
Family Cyprinidae (minnows and carps)
About 286 species of cyprinids, in N. America, over 40% areshiners
Emerald Shiner(Notropis atherinoides)www.dnr.state.oh.us/wildlife/ fishing/fishid/remainder.htm
http://www.dnr.state.oh.us/wildlife/fishing/fishid/remainder.htmhttp://www.dnr.state.oh.us/wildlife/fishing/fishid/remainder.htm -
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Size, shape, gape and position of the mouth often reflect
diet and habitat
Planktivore eats zooplankton
Piscivore eats fish
Detritivore eats organic material from sediments
Herbivore eats plants
Benthivore eats food on the bottom
Omnivore eats plants and animals
stewartsguideservice.com/ mixedbagarchive.htm
www.dbs.nus.edu.sg/.../ catfish/catfish.htm
http://stewartsguideservice.com/mixedbagarchive.htmhttp://stewartsguideservice.com/mixedbagarchive.htmhttp://www.dbs.nus.edu.sg/research/fish/aquarium/catfish/catfish.htmhttp://www.dbs.nus.edu.sg/research/fish/aquarium/catfish/catfish.htmhttp://stewartsguideservice.com/mixedbagarchive.htm -
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Planktivores eat zooplankton, but fish tend to eat
more of some species and less of others.
Which species do they
select, which species do
they avoid and why?
Fish often select for
larger, more visible
prey items
photo by M. Duffy
There are 2 major
reasons why...
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Pumpkinseed Lepomis gibbosus
1. Encounter frequency: Encounter of large prey is higherthan small prey
Reaction distancehowclose to the fish does a preyitem have to be for the fish
to see it and react to (eat)it?
www.state.ia.us/.../fwb/fish/ iafish/sunfish/pkse.gif
Confer and Blades 1975 (L&O)
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Reaction distance translates to overall volume searched,which influences vulnerability of the prey
Volume searched = volume of sphere = 4/3 r3
Reaction distance = radiusof sphere
Visual field is roughly spherical with ~ 20posterior blind segment
Longer radius = higherencounter rate
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2. Optimal foragingtake the prey that provides thegreatest energy return for cost of capture/handing.
With abundant prey, bigger is better
Werner and Hall (1974) Ecology
Fed fish choice of three sizes of Daphniamagna
0
20
40
60
80
Small (< 1.5 mm) Medium Large (>2.5 mm)
%i
ndiet
Expected from
encounter rates
Observed in Diet
Prey size
h l h ll h
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Bluegills feeding on Daphnia
Get exception to this bigger is better rule with small fishbecause ofgape limitation Li et al. 1989 Ecology
Walton et al. 1992 Ecology
Selectivity
IndexNo choice
Avoidsparticularanimals
Selects forparticularanimals
0
-1
+1
Small fish dont eat large prey
Daphniasize (mm)
Fish > 76 mm
Fish = 11 mm
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Two morphs of Ceriodaphnia
Big eye Small eye
It is not just size that matters, it is overall visibility
Artificially made small-eye morph more visible by feeding
them india ink. Predation rate increased
Zaret 1972
Fish always took the big-eye form.
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Reproductive Behavior
Most common type of reproduction is ovipary (external
fertilization of eggs)
Parental care ranges from broadcast spawning to
mouthbrooding
Many species build nests
www.venturenorth.com/ tlca/bass.htm
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Reproductive Behavior in Bluegill
Large parental males mature at age 7
or 8
Nesting males court and spawn with multiplefemales
M.R. Gross and colleagues
Lake Opinicon, Ontario, Canada
Parental males compete for space to build a nest
The males care for all offspring in the nest
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Reproductive Behavior in Bluegill
Some males mature at age 2 or 3sneakers
Other males mature at age 4 or 5satellites
M.R. Gross and colleagues
Sneakers do not make nests, but dart into the
nest while a female is releasing her eggs
Satellites look and act like females
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Parental care
Males fan and defend the eggs
After the eggs hatch, males defend the fry
Males do not feed during this time and expend
about 10% of their body mass
Can determine paternity through genetic
analysis
Neff and Gross 2001
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Neff and Gross 2001
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Graeb et al. 2004 found that larval yellow
perch (< 12 mm) avoided eating large
Daphniaand primarily consumed copepod
nauplii, whereas larger perch (> 16 mm)avoided the nauplii and consumed the
Daphnia.
Explain this result
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Concepts to know
What factors influence feeding of
planktivores?
What is the mating system in bluegill?