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Download Peruvian anchovy landings and El Niño events
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Oceanic ecosystems 1. Tectonics and ocean basin evolution 2. Late Cenozoic climates (and biogeographic consequences) 3. Ecosystem structure and function 4. Short-term spatio-temporal variations 5. Reef, forest, and smoker communities Oceanic environments area: ecosystem: basin trench ridge shelf slope continental plate open ocean 60% coastal 10% pelagic neritic terrestrial 30% Tectonics and ocean basin formation since 200 Ma BP 3 4 1 QuickTime™ and a GIF decompressor are needed to see this picture. 2 4 Major Cenozoic changes Tectonic (see previous slide) 1. 2. 3. 4. Opening of Atlantic Ocean Closing of Tethys Sea Closing of Panama gap Opening of Antarctic circulation Climatic a. Climatic cooling in polar latitudes b. Glacio-eustatic changes in relative sea level Divisions of the ocean ecosystem Nybakken, J.W. (2001) “Marine Biology”. Addison-Wesley-Longman Definitions of terms littoral: neritic: pelagic: benthic: abyssal: hadal: Spatio-temporal variations in sea-surface temperature QuickTime™ and a Photo decompressor are needed to see this picture. Phytoplankton: marine diatoms and dinoflagellates Light: required for photosynthesis. Phytoplankton are sensitive to light amount and quality. By modifying their buoyancy (and hence their depth in the water column), they can change their ambient light environment. CO2: required for photosynthesis. QuickTi me™ and a TIFF ( Uncompressed) decompressor are needed to see thi s pi ctur e. Nutrients: silicate (required to build diatom cell walls), and nitrate, phosphate and iron (required for cell metabolism) may be limiting resources for phytoplankton growth in many parts of the ocean. Temperature and phytoplankton growth Species Thermal environment (°C) Skeletonema tropicum 18 to 25 Skeletonema costatum 12 to15 Thalassiosira antarctica -2 to 4 Phaeocystis antarctica -2 to 4 Optimal temperature (°C) 10 to 20 10 to 20 10 to 20 10 to 20 year-round growth in tropics; seasonal production in temperate and polar waters Spatio-temporal variations in primary production QuickTime™ and a Photo decompressor are needed to see this picture. Temperature-depth profiles 0 -5 0 5 0 5 10 15 20 25 0 5 10 15 20 seasonal thermocline 500 permanent thermocline 1000 permanent thermocline 1500 2000 2500 3000 Arctic Temperate Tropical 25°C Plankton production in polar, temperate and tropical oceans phytoplankton zooplankton Nybakken, J.W. (2001) “Marine Biology”. Addison-Wesley-Longman Seasonal variations in thermal structure and nutrient concentration in temperate oceans Temperature Temperature thermocline Winter Summer Terrestrial vs. oceanic food chains Nybakken, J.W. (2001) “Marine Biology”. Addison-Wesley-Longman A simple marine food web: sub-Antarctic waters diatoms, dinoflagellates A marine carbon budget: Herbivore pathway an example from the English Channel Phytoplankton 100 61 Bacteria 22 17 Zooplankton 19 Protozoa 6 5 Microbial loop Flagellates 6 World ocean currents Currents and biotic migrations Image: FAO Seasonal variations in circulation L QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture. QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture. H Maps: Thompson et al., 1989. “Vancouver Island coastal current… Wind directions and water advection in coastal waters Images: http://www.crd.bc.ca/ Upwelling zones Fraser River plume Primary productivity in zones of coastal upwelling image: terra.nasa.gov Upwelling (in green) Tidal stream flowing over continental shelf margin (e.g. Bering Sea) Coriolis-induced divergence of surface equatorial currents Coriolis-induced offshore flow of coastal current (e.g. California Current) Ocean Fronts and Eddies FRONT: the interface between two water masses with differing physical characteristics (temperature and salinity) with resulting variations in density. Some fronts which have weak boundaries at the surface have strong “walls” below the surface. The boundary zones are sites of increased biological production. EDDY: a rotating mass of water with a ± uniform physical characteristics. They can be thought of as circular fronts. Their boundaries are associated with increased productivity. Fronts and eddies: Gulf Stream Labrador Current boundary zone QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture. seis.natsci.csulb.edu/rbehl/gulfstream.htm Oceanic front productivity QuickTime™ and a TIFF (LZW) decompressor are needed to see this picture. Iron fertilization experiment: polar Southern Ocean (I) days Iron fertilization experiment: polar Southern Ocean (II) days Sahara dust storm over adjacent Atlantic Ocean image: terra.nasa.gov El Niño - Southern Oscillation (ENSO) events El Niño (1982-83) QuickTime™ and a TIFF (LZW) decompressor are needed to see this picture. High SSTs and reduced upwelling of nutrients in eastern tropical Pacific Ocean Sea level and thermocline depth variations in the central Pacific during the El Niño event of 1997-8 QuickTime™ and a GIF decompressor are needed to see this picture. Variations in primary production in the vicinity of the Galapagos Islands during an El Niño - La Niña cycle El Niño La Niña Consequences of reduced upwelling ( e.g. 1982-83) N depletion in surface waters led to a drastic reduction in phytoplankton abundance Pelagic fish populations were heavily impacted e.g. Peruvian anchoveta (Engraulis ringrens) live for only three years and feed on diatoms and are therefore highly susceptible to shortterm environmental oscillations. South American sardine (Sardinops sagax) feed on copepods and diatoms and can live for up to 25 years. They are less sensitive to El Niño events than anchoveta. Peruvian anchovy landings and El Niño events 14000 12000 Landings (tons) 10000 8000 6000 4000 major minor 2000 0 1970 1975 1980 1985 1990 1995 2000 Ecological consequences of El Niño events QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture. Decadal-scale fluctuations: the Pacific Decadal Oscillation SST anomalies QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture. “warm phase” “cool phase” QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture. 14000 Russian sockeye catch 10000 tonnes PDO regime shifts and ecological consequences 12000 8000 6000 4000 2000 0 1940 1950 1960 1970 1980 1990 Deep-sea communities QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture. QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture. Feed on organic particles in ooze that accumulates on ocean floor at rates of <0.01 mm yr-1. Sediment includes aeolian deposits and biogenic detritus. Deep-sea communities • Largely (~80%) sediment deposit feeders; • Predators include crustaceans and primitive fish; • Spatially and temporally variable, despite apparent locally uniform water masses; • Diverse (= numerous sediment microhabitats and heavy predation?) but poorly known; ?10 M species yet to be described from deep-sea sediments. Major hydrothermal vents Nybakken, J.W. (2001) “Marine Biology”. Addison-Wesley-Longman Hydrothermal vent communities QuickTime™ and a Video decompressor are needed to see this picture. “black smoker” releasing sooty, mineralrich, hot ( 350°C) water, H2S and CO2 Food web (generalized) Nybakken, J.W. (2001) “Marine Biology”. Addison-Wesley-Longman Kelp “forests” A subtidal forest in the Aleutian Islands, Alaska. Cymathera triplicata (foreground); Alaria fistulosa (rear). Kelp forests in the northeastern Pacific commonly have complex threedimensional structure, with many coexisting species. As in terrestrial forests, shading is a major mechanism of competition. Image and text: life.bio.sunysb.edu/marinebio/kelpforest.html Distribution of kelp species with depth (California) Layers 1. 2. 3. 4. red algae and coralline algae prostate-canopy kelp erect understorey kelp floating canopy Nybakken, J.W. (2001) “Marine Biology”. Addison-Wesley-Longman Kelp biogeography Miocene? 26 genera 5 genera ~83 spp. 11-18 spp. QuickTime™ and a TIFF (Uncompressed) decompressor Pliocene? are needed to see this picture. Pleistocene? 4 genera 10-12 spp. Originated in north Pacific in early Cenozoic; rapid radiation of new forms; dispersed in mid to late Cenozoic? to N. Atlantic, and in Pleistocene? to southern oceans. Kelp forest food webs Orcas (1990s) QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture. QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture. research.amnh.org/biodiversity/crisis/foodweb.html Effects of sea otters on species diversity of kelps in southern Alaska no otters present otters <2 yr otters >15 yr Torch Bay Deer Harbor Surge Bay Diversity Index (H') 0.5 Sea otter harvesting sea urchin 0.4 0.3 0.2 0.1 0 Succession in an Alaskan kelp forest Note high diversity in the early intermediate successional phases; “climax” consists of a selfreplacing Laminaria bed (shade tolerant) Image: David Duggins