Modern * Skeleton-Breaking Predators Structure Temperate and Tropical Benthic Communities

1. Teleostean Fish Neoselachian Sharks and Rays Decapod Crustaceans Modern* Skeleton-Breaking Predators Structure Temperate and Tropical Benthic Communities *Modern = Product of Post-Paleozoic Radiations of Shell-Breaking Functional Groups

2. Cenozoic Era Modern predators begin to diversify Mesozoic Era Paleozoic Era

3. Functionally Modern, Shell-Crushing Predators are Absent from theAntarctic Shallow Benthos No crabs or lobsters. No sharks or rays. The bony fish (notothenioids) eat amphipods and other soft foods. BAS BAS

4. Polar: Antarctic Tropical Temperate Inferred Latitudinal Gradients: Calcification Predation www.gastropods.com After G. J. Vermeij

5. 0° Africa South America 90° S 90° S McMurdo Sound Antarctic Circle 66° 32' S Australia 180° NZ

7. Top Predators: Slow-Moving Invertebrates of a Paleozoic Functional Grade

8. Top Predators: Slow-Moving Invertebrates of a Paleozoic Functional Grade

9. Julian Gutt, AWI

10. 0° Africa SeymourIsland South America 90°S 90°S Antarctic Circle 66° 32' S Australia 180° NZ

11. Seymour Island Fossils from 55–33.5 million years ago Eocene La Meseta Fm

12. Eocene Epoch Paleozoic Era

15. Fossil Brittlestars

16. Fossil Sea Lilies

17. The 41-Ma Cooling Event • Predation pressure reduced. • Appearance of dense crinoid and ophiuroid populations. • Appearance of undefended gastropods.

18. Morphometric Analysis (MDS) of Gastropod Shells: Architectural Defenses Against Predatory Crabs Antarctodarwinella Conomitra Struthioptera Zelandiella Polinices Taioma Post-Cooling Genera (poorly defended) Pre-Cooling Genera (well defended) Calliostoma 2D stress = 0.153 3D stress = 0.900

19. 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.

20. 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?

21. Why No Shell-Crushing Predators? Decapod Crustaceans Problem 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.

22. Paralomis birsteini (Lithodidae): Continental Slope, 1100 m Bellingshausen Sea off the Antarctic Peninsula January 2007 Water Temperature: 1–2 °C

23. Global 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 andwill be warm enough for modern predators within the next 50–100 years.

24. 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.

25. McClintock et al. 2008. American Scientist.

26. McClintock et al. 2008. American Scientist.