modern* skeleton-breaking predators structure temperate and tropical benthic communities teleostean...
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Modern* Skeleton-Breaking Predators Structure Temperate
and Tropical Benthic Communities
Modern* Skeleton-Breaking Predators Structure Temperate
and Tropical Benthic Communities
Teleostean Fish
Neoselachian Sharks and Rays
Decapod Crustaceans
Teleostean Fish
Neoselachian Sharks and Rays
Decapod Crustaceans
*Modern = Product of Post-Paleozoic Radiations of Shell-Breaking Functional Groups*Modern = Product of Post-Paleozoic Radiations of Shell-Breaking Functional Groups
Paleozoic EraPaleozoic Era
Mesozoic EraMesozoic Era
Modern predators begin to diversifyModern predators begin to diversify
Cenozoic EraCenozoic Era
Functionally Modern, Shell-Crushing Predators are Absent from the
Antarctic Shallow Benthos
Functionally Modern, Shell-Crushing Predators are Absent from the
Antarctic Shallow Benthos• No crabs or lobsters.
• No sharks or rays.
• The bony fish (notothenioids) eat amphipods and other soft foods.
• No crabs or lobsters.
• No sharks or rays.
• The bony fish (notothenioids) eat amphipods and other soft foods.
BASBAS
BASBAS
TemperateTemperateTropicalTropical
Polar: AntarcticPolar: Antarctic
After G. J. VermeijAfter G. J. Vermeij
Inferred Latitudinal Gradients:CalcificationPredation
Inferred Latitudinal Gradients:CalcificationPredation
www.gastropods.comwww.gastropods.com
Top Predators: Slow-Moving Invertebrates of a Paleozoic Functional GradeTop Predators: Slow-Moving Invertebrates of a Paleozoic Functional Grade
Top Predators: Slow-Moving Invertebrates of a Paleozoic Functional GradeTop Predators: Slow-Moving Invertebrates of a Paleozoic Functional Grade
Seymour IslandSeymour IslandFossils from 55–33.5Fossils from 55–33.5
million years agomillion years ago
Seymour IslandSeymour IslandFossils from 55–33.5Fossils from 55–33.5
million years agomillion years ago
Eocene La Meseta Fm
The 41-Ma Cooling EventThe 41-Ma Cooling Event
• Predation pressure reduced.
• Appearance of dense crinoid and ophiuroid populations.
• Appearance of undefended gastropods.
• Predation pressure reduced.
• Appearance of dense crinoid and ophiuroid populations.
• Appearance of undefended gastropods.
Morphometric Analysis (MDS) of Gastropod Shells:Architectural Defenses Against Predatory Crabs
Post-Cooling Genera(poorly defended)
Pre-Cooling Genera (well defended)
2D stress = 0.1533D stress = 0.900
Struthioptera
Conomitra
Polinices
Antarctodarwinella
Zelandiella
Calliostoma
Taioma
Why No Shell-Crushing Predators?Why No Shell-Crushing Predators?General Physiological Barriers
• Calcification is costly at cold temperatures.
• Power output of muscle at 0 °C is one-tenth that at 25 °C.
General Physiological Barriers
• Calcification is costly at cold temperatures.
• Power output of muscle at 0 °C is one-tenth that at 25 °C.
Teleosts• Atifreeze fish—notothenioids—are the only
teleosts living in Antarctica, and they are not shell-crushers.
• Teleosts living in the Arctic that ARE shell-crushers have independently evolved THE SAME AFGPs.
Teleosts• Atifreeze fish—notothenioids—are the only
teleosts living in Antarctica, and they are not shell-crushers.
• Teleosts living in the Arctic that ARE shell-crushers have independently evolved THE SAME AFGPs.
Why No Shell-Crushing Predators?Why No Shell-Crushing Predators?
Decapod CrustaceansProblem of Magnesium Regulation
• Crabs and lobsters cannot regulate Mg2+ ions in their blood at low temperatures. They pass out and die when sea temperatures dip to 0–1°C.
• King crabs and hermit crabs also have this problem. King crabs (Lithodidae) tolerate temperatures of 1–2°C by operating in a torpid, hypometabolic state.
• Isopods and amphipods don’t have this problem. They are all over the Antarctic benthos.
Decapod CrustaceansProblem of Magnesium Regulation
• Crabs and lobsters cannot regulate Mg2+ ions in their blood at low temperatures. They pass out and die when sea temperatures dip to 0–1°C.
• King crabs and hermit crabs also have this problem. King crabs (Lithodidae) tolerate temperatures of 1–2°C by operating in a torpid, hypometabolic state.
• Isopods and amphipods don’t have this problem. They are all over the Antarctic benthos.
Why No Shell-Crushing Predators?Why No Shell-Crushing Predators?
Paralomis birsteini (Lithodidae): Continental Slope, 1100 m Bellingshausen Sea off the Antarctic PeninsulaJanuary 2007
Paralomis birsteini (Lithodidae): Continental Slope, 1100 m Bellingshausen Sea off the Antarctic PeninsulaJanuary 2007
Water Temperature: 1–2 °C
Water Temperature: 1–2 °C
Global Warming in AntarcticaGlobal Warming in Antarctica• Summertime SSTs off the western
Antarctic Peninsula have increased ~1°C in the last 50 years.
• That is double the global average.• Shelf habitats along the Peninsula are
now at 0–1°C and will be warm enough for modern predators within the next 50–100 years.
• Summertime SSTs off the western Antarctic Peninsula have increased ~1°C in the last 50 years.
• That is double the global average.• Shelf habitats along the Peninsula are
now at 0–1°C and will be warm enough for modern predators within the next 50–100 years.
Avenues for Reinvasionof Antarctica
Avenues for Reinvasionof Antarctica
• Eddies from the ACC transport crab larvae, which will be more likely to survive as sea temperatures rise and the growing season expands.
• Increasing ship traffic has already introduced alien crabs from the Subarctic!!
• King crab populations on the continental slope will move into shallow-water shelf habitats as sea temperatures rise.
• Eddies from the ACC transport crab larvae, which will be more likely to survive as sea temperatures rise and the growing season expands.
• Increasing ship traffic has already introduced alien crabs from the Subarctic!!
• King crab populations on the continental slope will move into shallow-water shelf habitats as sea temperatures rise.
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