Transcript Fish Fauna of the Great Lakes

Fish Fauna of the Great Lakes
1. Who are they?
2. Where did they come from?
3. What is the nature of the
interactions among species?
1. Who are they? - How many
are there?
 Low diversity:
– Native:
157 species
– Introduced: 22 species
– TOTAL:
179 species
Comparison with other fish
faunas
 Laurentian Great Lakes: 179 species
 Coral Reefs: > 150 on 1 coral head
 Mississippi River Basin:> 330 species
 Amazon River Basin: > 2,000 species
 African Great Lakes: > 450 species
ENDEMIC in one lake!
Why is diversity low?
Temperature
Why is diversity low?
Temperature
Productivity
Why is diversity low?
Temperature
Productivity
Age
Why is diversity low?
Temperature
Productivity
Age
Connections - to other lake and river
basins
1. Who are they? - Two
ecological groupings:
 Coldwater, deep
lake group:
 Coolwater, shallow
basin group:
1. Who are they? - Two
ecological groupings:
 Coldwater, deep
lake group:
 lake trout
 lake whitefish
 lake herring
 lake sturgeon
 deepwater sculpin
 deepwater ciscos
 Coolwater, shallow
basin:
1. Who are they? - Two
ecological groupings:
 Coldwater, deep
 Coolwater, shallow
lake group:
 lake trout
 lake whitefish
 lake herring
 lake sturgeon
 deepwater sculpin
 deepwater ciscos
basin:
 yellow perch
 walleye
 white bass
 channel catfish
 northern pike
 smallmouth bass
1. Who are they? - A New
Group: Introduced species
 Intentional introductions:
– Common carp, brown trout, steelhead,
chinook and coho salmon
Introduced species
Intentional introductions:
Common carp, brown trout, steelhead,
chinook and coho salmon
Accidental introductions:
Alewife, sea lamprey, white perch, pink
salmon, rainbow smelt, round goby, ruffe
2. Where did the native
species come from?
Endemic species
Immigrant species
2. Where did the native
species come from?
 Endemic species
– species evolved in the system and are
unique to the system:
• Blue pike (walleye subspecies)
• Deepwater ciscos
2. Where did the native
species come from?
 Immigrant Species:
– species that evolved elsewhere and
entered the system from other watersheds:
• Mississippi Basin: 79% of fauna
• Atlantic drainages: 9% of fauna
• Both: 12% of fauna
3. What is the nature of the
interactions among species?
 Predator-Prey relations
3. What is the nature of the
interactions among species?
 Predator-Prey relations
 Niche partitioning (generalists vs.
specialists)
 Resilient species (to heavy fishing
pressure or predation pressure)
 Sensitive species (to heavy fishing
pressure or predation pressure)
3. What is the nature of the
interactions among species?
 Effects of introduced species:
– sea lamprey
• Parasites on large fish - lake trout are small
compared with their ocean hosts
• Cause high mortality on lake trout
• Best opportunity for control is in reproductive
and larval stages - concentrated in rivers
3. What is the nature of the
interactions among species?
 Effects of introduced species:
– rainbow smelt and alewife - planktivores
• compete with native planktivores
• prey on larvae of native fish species
• prey on and compete with each other!
3. What is the nature of the
interactions among species?
 Effects of introduced species:
– gobies & ruffe - benthic fishes
• new immigrants to system
• ballast water introductions of 1980’s
• potential to be competitors and predators on
benthic fishes and invertebrates
Zoogeography of Marine Fishes
Ch. 26 in Moyle & Cech
Barriers to Dispersal in Marine
Systems
 Continents - e.g. Atlantic vs. Pacific faunas
 Temperature - e.g. tropical vs. temperate vs.
polar
 Salinity - e.g. estuaries, freshwater (Panama
Canal)
 Depth - deep-dwelling fishes can be isolated
by submerged mountain ranges
Mechanisms for Dispersal in
Marine Fishes
 Directed movements (e.g., with changes in
temperature; migrations)
 Pelagic eggs/larvae - current-born dispersal
 Human action - transplants (e.g., striped
bass, American shad in Pacific Ocean; 250
species introduced into San Francisco Bay)
Zoogeographic Groupings of
Marine Fishes
 Continental Shelf (neritic) – 45% of all fishes
– Tropical Zone
– Temperate (North & South) Zones
– Arctic/Antarctic Zones
 Pelagic
 Abyssal
Zoogeographic Groupings of
Marine Fishes
 Pelagic – Epipelagic (1.3% of all fish species)
– Meso- & Bathypelagic (5% of all fish species)
– Arctic
– Temperate
– Subtropical
– Tropical
Zoogeographic Groupings of
Marine Fishes
 Continental Shelf (neritic)
 Pelagic
 Deep benthic (abyssal)
– 6.5% of all fish species
– little known about these
Example: Distribution of pelagic
piscivores in north Pacific Ocean
 Arctic:
– Arctic char, pink salmon, some cods
– distributed north of 0° isotherm
 North Temperate:
 North Subtropical:
 Tropical:
Example: Distribution of pelagic
piscivores in north Pacific Ocean
 Arctic:
 North Temperate:
– coho, chinook, steelhead, sockeye, chum
salmon
– north of 14° isotherm, south of 0° isotherm
 North Subtropical:
 Tropical:
Example: Distribution of pelagic
piscivores in north Pacific Ocean
 Arctic:
 North Temperate:
 North Subtropical:
– some tunas, marlins, basking sharks, mackerel
sharks
– north of 20° isotherm, south of 14° isotherm
 Tropical:
Example: Distribution of pelagic
piscivores in north Pacific Ocean
 Arctic:
 North Temperate:
 North Subtropical:
 Tropical:
– flying fish, tunas, whale sharks, marlins
– south of 20° isotherm in northern hemisphere
and north of 20° isotherm in southern
hemisphere
Ecology of Coral Reef Fishes
Chapter 33
Moyle & Cech
Distribution of Coral Reef
Ecosystems
 Found in Tropical and subtropical oceans
– Mean annual temperature > 20 C
– Influenced by currents
• e.g., Gulf Stream brings warm Caribbean water to
mid-Atlantic
• corals and coral reef fishes are found as far north as
Bermuda (32° North)
Diversity of fish assemblages in
Coral Reef Ecosystems
 Indo-West Pacific: 3000 species
– Great Barrier Reef: 1200 species
 Western Atlantic & Caribbean:
– 1200 species
 Eastern Pacific: < 800 species
 Eastern Atlantic: < 500 species
Diversity of fish assemblages in
Coral Reef Ecosystems
 Western Atlantic & Caribbean:
– 1200 species
– Bahamas: 560 species
– San Salvador Island, Bahamas: 300 - 400
species
– Dump Reef, San Salvador Island, Bahamas:
> 120 species
How did diversity originate?
 Uncertain, but these factors probably
important:
– Time: long evolutionary record of coral reef
systems
– Productivity: high productivity of coral reef
systems
– Temperature: rapid growth rates, short
generation times of coral reef systems
How did diversity originate?
 Probable important factors, cont.:
– Complexity: highly complex physical structure
of reef
– Size: small size of many species (highest
diversity in the gobies and blennies - many < 50
mm at maturity
– Niche specialization: high degree of specificity
to habitat and diet
– Mechanisms of isolation?
How does diversity persist?
(how do so many species get along with out
competitive exclusion kicking in?)
 Competition hypothesis:
– all species are specialists resulting from past
competition - suggests equilibrium (saturation)
state
 Recruitment limitation hypothesis:
 Predation hypothesis:
How does diversity persist?
(how do so many species get along with out
competitive exclusion kicking in?)
 Competition hypothesis:
 Recruitment limitation hypothesis:
– resources are not limiting, survival to
settlement is limited, chance of settlement is
rare and random - “lottery” hypothesis
 Predation hypothesis:
How does diversity persist?
(how do so many species get along with out
competitive exclusion kicking in?)
 Competition hypothesis:
 Recruitment limitation hypothesis:
 Predation hypothesis:
– Predation intensity is high on young fish, few
survive to colonize, resulting in random species
assemblages
Zoogeography of
Freshwater Fishes
Definition & Overview
 Zoogeography - the study of the
distributions of animal taxa over the surface
of the earth
 Unique aspects of piscine zoogeography:
– longer period of record (since 350 mybp)
– constraints to dispersal in aquatic habitats (land
masses)
– unique dispersal mechanisms - current
movement of planktonic eggs & larvae
Interpretation of distribution
patterns requires:
 Ecological information - e.g., can the fish
taxa tolerate exposure to fresh water or salt
water
– freshwater dispersants - e.g., minnows - cannot
tolerate any salinity
– Saltwater dispersants - freshwater fishes that
can tolerate salinity - e.g., cichlids
Interpretation of distribution
patterns requires:
 Geological information - what have been
the past connections between water bodies
– past and present watershed configurations
important - e.g. previous connections between
Great Lakes basin and Mississippi River - 79%
of fishes in GL Basin originated from
Mississippi basin
Interpretation of distribution
patterns requires:
 Geological information - continental drift
– a single continent (Pangaea) existed as recently
as Triassic (200 mybp)
– Pangaea split into two continents at end of
Triassic (180 mybp):
• Northern continent - Laurasia (modern Eurasia &
North America
• Southern continent - Gondwana (modern Africa,
South America, Australia, Antarctica, India)
Interpretation of distribution
patterns requires:
 Geological information - continental drift
– Gondwana split in Jurassic & Cretaceous
• Australia broke off first
• South America broke off later
– Several fish taxa are present only on southern
continents:
• lungfishes - Australia, S. America, Africa
• cichlids - S. America, Africa, India
• characins - S. America, Africa
Interpretation of distribution
patterns requires:
 Geological information - continental drift
– Laurasia split in Jurassic (120 mybp)
• North America separated from Eurasia
– Several fish taxa are present only on northern
continents:
•
•
•
•
•
Cyprinids (also have moved into Africa recently)
Percids - Holarctic (in N. America & Eurasia)
Catostomids - Nearctic (largely in N. America)
Centrarchids - Nearctic (only in N. America)
Cobitids - Palearctic (only in Eurasia)
Mississippi Basin Fauna
illustrates these patterns well
 Contains ~ 330 species, 13 families
 Basin is ancient - present arrangement since
Rocky Mtns. formed in Tertiary (~65 mybp)
 Ancient relics are extant today - have
benefited from persistence of the basin:
– Chondrosteans - sturgeons, paddlefish
– gars, bowfins
– mooneyes, pirate perch, cavefishes - only found
here
Mississippi Basin Fauna
illustrates these patterns well
 New taxa originated and/or flourished here:
– Notropis/Cyprinella minnows (shiners)
– Etheostoma/Percina percids (darters)
– ictalurids (catfishes), especially Noturus madtoms
– centrarchids, especially Lepomis (sunfishes)
– catostomids, especially Moxostoma (redhorses)
Why is the Mississippi fauna so
diverse?
 Provided a refuge from glaciers, due to
north-south axis - taxa could retreat south as
glaciers moved south
Why is the Mississippi fauna so
diverse?
 Provides a diversity of habitats:
– Different stream types:
• Coastal plain (Gulf of Mexico margin)
• Interior highlands
– Ozarks
– Tennessee/Kentucky plateau
• Interior lowlands
– Western (Missouri River basin)
– Central (Upper Mississippi River basin)
– Eastern (Ohio River basin)
Why is the Mississippi fauna so
diverse?
 Provides a diversity of habitats:
– Speciation requires isolation - offered by these
diverse AND separated habitat types
• e.g., Ozark fauna is unique from the
Tennessee/Kentucky fauna, even though the habitats
are similar - the Mississippi River valley separates
them - no passage possible between for small taxa
like darters, minnows, madtoms
Why is the Mississippi fauna so
diverse?
 Provides a diversity of habitats:
– Species dependent on small, headwater streams
are more easily isolated, and therefore are the
most diverse groups
• shiners
• darters
• madtoms