Oceanography 101, Richard Strickland Lecture 26 © 2006 University of Washington Oceanography 101, Richard Strickland Lecture 26 © 2006 University of Washington Pelagic Food Web: Review Pelagic Food Web: Herbivores • Primary Producers • Primary Consumers – Diatoms – Microzooplankton • www.ucl.ac.uk/GeolSci/micropal/foram.htm www.radiolaria.org – Crustaceans – Dinoflagellates • Copepods • Herbivorous krill – Pteropods – Microflagellates – Larvae – Chordates 1 2 Barnacle Oceanography 101, Richard Strickland Lecture 26 © 2006 University of Washington Oceanography 101, Richard Strickland Lecture 26 © 2006 University of Washington Pelagic Food Web: Carnivores Pelagic Food Web: Carnivores • Secondary consumers preying on zooplankton • Tertiary consumers preying on herbivorous & – Gelatinous zooplankton carnivorous zooplankton • Medusae – Fish (“baitfish,” “forage fish”) • Ctenophores • Herring • Siphonophores • Anchovy • Chaetognaths • Sardine – Crustaceans • Smelt • Carnivorous krill • Sand Lance – Amphipods & juveniles shrimp • Juvenile salmon • Predatory copepods – Invertebrates – Fish larvae & juveniles • Squid 3 4 http://jaffeweb.ucsd.edu/pages/celeste/copepods.html Oceanography 101, Richard Strickland Lecture 26 © 2006 University of Washington Oceanography 101, Richard Strickland Lecture 26 © 2006 University of Washington Pelagic Food Web: Carnivores Pelagic Food Web: Carnivores • Tertiary consumers preying on herbivorous & • Predators on krill zooplankton & small fish carnivorous zooplankton • Mammals – Planktivorous Fish – Baleen whales • Pink salmon – Filter feeders Sockeye salmon • • Blue Pollock • • Minke • Hake • Humpback Cod • • Right • Dogfish 6 • Fin • Lanternfish • Sei 5 Oceanography 101, Richard Strickland Lecture 26 © 2006 University of Washington Oceanography 101, Richard Strickland Lecture 26 © 2006 University of Washington Pelagic Food Web: Carnivores Pelagic Food Web: Carnivores • Predators on krill zooplankton & small fish • Predators on small fish • Diving birds – Coho salmon – Puffins • Chum salmon – Murres • Chinook salmon • Mackerel – Auklets • Top predators – Guillemots – Tuna – Grebes – Sharks – Pelicans – Billfish – Albatrosses 7 8 Oceanography 101, Richard Strickland Lecture 26 © 2006 University of Washington Oceanography 101, Richard Strickland Lecture 26 © 2006 University of Washington Pelagic Food Web: Carnivores Generic Food Web • 5. Large fish, • Top predators: Mammals birds, – Seals mammals • 4. Small fish – Sea lions (herring, smelt) – Toothed whales • 3. Carnivorous • Orca zooplankton (medusae, • Porpoise (dolphin) amphipods, some • Sperm copepods, fish larvae) • 2. Herbivorous zooplankton (copepods, larvae) • 1. Phytoplankton 9 Oceanography 101, Richard Strickland Lecture 26 © 2006 University of Washington Oceanography 101, Richard Strickland Lecture 26 © 2006 University of Washington Food Webs in Different Zones Productivity in Ocean Zones • Differences dictated by two properties: – Amount of primary productivity – Type of phytoplankton • Upwelling zones – High productivity • Upwelling zones have – Large, fast-growing diatoms highest productivity • Neritic zones & temperate oceanic zone – Nutrient supply – Moderate productivity • Coasts (& temperate – Large diatoms mixed with dinoflagellates oceans) next • Low-latitude oceanic zone • Low-latitude open ocean NOTE: Biomass used here as 11 – Low productivity of small microflagellates 12 lowest an indicator of productivity Oceanography 101, Richard Strickland Lecture 26 © 2006 University of Washington Oceanography 101, Richard Strickland Lecture 26 © 2006 University of Washington Productivity in Ocean Zones Productivity in Ocean Zones • Upwelling zones still • But upwelling zones provide <1% of total provide 58% of total ocean production fish production – Small area • Coasts (& temperate • Coasts (& temperate oceans) 37%, open oceans) next, open ocean ocean 5% NOTE: Biomass used here as NOTE: Biomass used here as 13 highest because of area an indicator of productivity 14 – Why? an indicator of productivity Oceanography 101, Richard Strickland Lecture 26 © 2006 University of Washington Oceanography 101, Richard Strickland Lecture 26 © 2006 University of Washington Productivity in Ocean Zones Food Webs in Upwelling Zones • Peru a special case – Primary producers large, fast-growing diatoms – Primary consumer Peruvian anchovy • An unusual herbivorous fish Upwelling zones • – Result: fishery harvest @ trophic level 2 have: – Dense, compact area of production – Shorter food chains • Efficiency = 20% – Greater trophic • Less energy expended to search for food efficiency • Harvestable • The main difference fish production NOTE: Biomass used here as = 20% of primary 15 is in the food chains an indicator of productivity 16 production • Oceanography 101, Richard Strickland Lecture 26 © 2006 University of Washington Oceanography 101, Richard Strickland Lecture 26 © 2006 University of Washington Food Webs in Upwelling Zones Food Webs in Neritic Zones • More typical upwelling area: California • Example area: Bering Sea – Primary producers – Primary producers • Large, fast-growing diatoms • Nutrients not as abundant – Primary consumers (level 2) • Diatoms & dinoflagellates • Copepods & krill – Primary consumers (level 2) – Secondary consumers (level 3) • Copepods & krill • Anchovies & sardines – Secondary consumers (level 3) – Tertiary consumers (level 4) • Carnivorous ZP & juvenile fish • Mackerel, salmon – Tertiary consumers (level 4) – Fish harvest from levels 3 & 4 • Pollock, salmon • Estimated global production – Fish harvest from levels (3 &) 4 4 5 6 17 46 * 10 - 10 , not 10 18 • Food less concentrated, 15% efficiency Oceanography 101, Richard Strickland Lecture 26 © 2006 University of Washington Oceanography 101, Richard Strickland Lecture 26 © 2006 University of Washington Food Webs in Oceanic Zones Food Webs in Oceanic Zones • Example area: North Pacific • Example area: North Pacific – Primary producers – Tertiary consumers (level 4) • Nutrients scarce: microflagellates • Small oceanic fish • Nitrogen fixing cyanobacteria – Lanternfish (myctophid) Productivity sustained by nutrient » Most abundant fishes in the world • because of open ocean area? regeneration near surface – Flying fish – Primary consumers (level 2) – Dorado (mahi mahi) • Microzooplankton – Ocean sunfish (mola mola) – Secondary consumers (level 3) – Mostly not significant • Carnivorous copepods & krill commercially harvested • Same size as herbivorous species species that live in more productive waters • Too expensive to catch 19 20 for market value Oceanography 101, Richard Strickland Lecture 26 © 2006 University of Washington Oceanography 101, Richard Strickland Lecture 26 © 2006 University of Washington Food Webs in Oceanic Zones Food Webs in Oceanic Zones • Example area: North Pacific • Example area: North Pacific – Top predators (level 5) – Five-level food chain • Large oceanic fish – Lower trophic efficiency (10%) – Tuna • Energy expended to find widely – Swordfish, marlin dispersed food by energetic migrators – Sharks – Result: – Significant commercially harvested species • Classic food-chain model of 10% loss at each trophic level • Valuable enough to justify expense of • Harvestable fish production is 10-5 fishing far from shore times primary production • They save fishermen the work of scouring the sea to catch smaller fish – Combination of: • Highly mobile, energetic migrators • Low primary productivity, small 21 22 phytoplankton, widely dispersed food Oceanography 101, Richard Strickland Lecture 26 © 2006 University of Washington Oceanography 101, Richard Strickland Lecture 26 © 2006 University of Washington Food Chain Productivity Food Chain Productivity • Trophic pyramid is a simple (simplistic) model • Upwelling – Illustrates underlying principles of: – 1000 * (0.2) = 200 • Number of – 1000 * (0.2)2 = 40 trophic levels • Neritic • Differences – 1000 * (0.15)3 = 3.4 in trophic • Oceanic efficiency – 1000 * – This diagram (0.1)4 does not = 0.1 include diff- erences in 23 primary productivity 24.