Distribution of Life in the Oceans
Distribution of Life plankton (passive floaters)
nekton benthon pelagic (active swimmers) in the Oceans (bottom-dwellers) benthic epifauna infauna
Here, There, and Pelagic refers to the water column from surface to the just above the bottom Almost Everywhere Benthic refers to the seafloor from salt marsh to the deepest trench There are many more benthic species of animals than pelagic species ~98% of all marine animal species live on or near the seafloor
Mr. Ray sings … Ocean habitats (“ biozones ”)
the pelagic (water column) environments broad: neritic zone – overlies continental shelf oceanic zone – beyond shelf break specific: epipelagic zone – illuminated surface layer mesopelagic zone – “twilight,” no photosynthesis bathypelagic zone “Oooh , let's name the zones, the zones, the zones, – totally dark, no living plants Let's name the zones of the open sea! abyssalpelagic zone Mesopolagic , bathypelagic, abyssalpelagic , – more than ½ ocean volume All the rest are too deep for you and me to see.” hadalpelagic zone – deep -sea trenches
1 Ocean habitats (“ biozones ”) Light penetration zones
the benthic (bottom) environments photic zone – depth where light is sufficient for photosynthesis shallow (shelf): dysphotic zone – depth where illumination is too weak for littoral ( intertidal ) zone – between high and low tide photosynthesis sublittoral zone – beach to shelf break aphotic zone – receives no light from the surface because it is all absorbed by the water above deep: bathyal zone epipelagic zone photic – continental slope & rise – illuminated surface layer zone – beneath mesopelagic and mesopelagic zone bathypelagic zones dysphotic – “twilight,” no photosynthesis zone abyssal zone bathypelagic zone – average deep ocean bottom – totally dark, no living plants – beneath abyssalpelagic zone abyssalpelagic zone hadal zone aphotic – more than ½ ocean volume – deep -sea trenches zone – beneath hadalpelagic zone hadalpelagic zone – deep -sea trenches
Some terms Plankton – “passive floaters”
plankton Heterotrophs - organisms that require food (passive floaters) in the form of organic compounds prefabricated nekton benthon pelagic by other organisms (active swimmers) (bottom-dwellers) benthic Autotrophs - organisms that can synthesize epifauna organic compounds (their body tissues) from infauna inorganic substances (nutrients) phytoplankton - microscopic, single -celled, photosynthetic that is, they make their own food algae (diatoms, dinoflagellates , coccolithophorids ) two types: zooplankton - includes some animals (copepods, krill, jellies) 1. photosynthetic organisms utilize solar energy to power photosynthesis and microscopic, single -celled intermediate plant/animal life live in the photic zone forms (flagellates, ciliates, forams ) 2. chemosynthetic organisms bacterioplankton - many kinds of heterotrophic bacteria, and utilize chemical reactions to power chemosynthesis some photosynthetic bacteria ( cyanobacteria ) commonly live near deep sea vents meroplankton - larval stage of some benthonic and nektonic animals (spend early part of life as plankton)
2 Diatom Phytoplankton (mostly (single -celled alga; here in a chain) colonial diatoms here)
Note the green color due to the presence of chlorophyll
Trichodesmium filamentous cyanobacterium
Shrimp -like krill Copepods are flea -sized crustaceans; they are the most abundant animal in the ocean!
3 ctenophores jellyfish members of the zooplankton community
other gelatinous plankton
Portuguese man -o-war Bolinopsis
jellyfish & ctenophore Ctenophores
Physophora jellyfish stranded on shore (a siphonophore )
4 Pandea
Aequorea Meroplankton part -time plankton: larval stages of benthonic & nektonic invertebrate & vertebrate animals Benthocondon
barnacle larva Meroplankton newly hatched squid larvae shrimp or lobster larva Meroplankton jellyfish larva
crab larva sea urchin larva crab larva peanut worm larva
5 MOCNESS Plankton Tow
MOCNESS plankton tow (Multiple Opening/ Closing Net and Environmental Sampling System
Deck incubator for studies plankton nets of living plankton
6 Nekton – “active swimmers”
plankton (passive floaters)
nekton yellow -fin tuna benthon pelagic (active swimmers) (bottom-dwellers) benthic epifauna infauna puffer fish
organisms capable of moving independently of ocean currents some invertebrates (squid) many marine vertebrates (pelagic fish, marine mammals, marine reptiles) red tail wrasse giant sunfish
Red Sea surgeonfish Reef Shark
skates
Great White Shark blue -spotted wrasse
yellow belly damselfish Hammerhead Sharks
blue tang surgeonfish Whale Shark
7 Harbor Seal “Flipper” Leatherback turtle
Gray Whale
Humpback Whales Nautilus
Benthon – “bottom -dwellers”
plankton (passive floaters)
nekton benthon pelagic (active swimmers) (bottom -dwellers) benthic epifauna infauna
organisms that live on the seafloor ( epifauna & epiflora ) or buried within sediments ( infauna ): most marine invertebrates (clams, mussels, oysters, snails, barnacles, lobsters, crabs, sea urchins, starfish, sea cucumbers , corals, anemones, sponges, worms) attached plants (sea grasses) and algae (kelp and other seaweeds) “ground fish” (flounder, sole, cod, haddock) anemones ( epifauna )
8 Giant tube worm abalone scallop
Giant clam
Brittle star
Environmental controls on distribution
light our focus … temperature temperature salinity salinity food availability water density water viscosity dissolved nutrients pollution space to live cover habitat
9 Effects of Temperature Effects of Salinity
Rates of diffusion, osmosis, and metabolism are strongly Salinity is an important control on the distribution of temperature -dependent . Salinity is an important control on the distribution of The higher the temperature, the higher the rate of molecular organisms because of osmotic pressure . movement into or out of cells, and the higher the rate of biological Stenohaline organisms can tolerate only a narrow range activity including growth rates, motility, and life span. of salinity (deep and/or mobile organisms). Temperature also controls the concentration of dissolved Many organisms are not be able to tolerate the high salinities gases in water (CO 2 for photosynthesis, O 2 for animal (>40‰) of some subtropical lagoons or the reduced salinities respiration) (<30 ‰) of coastal waters or estuaries The higher the temperature, the less dissolved gas that water can Euryhaline organisms can tolerate a wider range of hold (i.e., cold water holds more dissolved gas) Euryhaline organisms can tolerate a wider range of salinities (surface and/or sessile organisms). Stenothermal organisms can tolerate only a narrow range of temperatures (deep and/or mobile organisms) Coastal organisms must be able to cope with daily and seasonal swings in salinity related to tidal movement, evaporation, precipitation Eurythermal organisms can tolerate a wider range of and river runoff temperatures (shallow and/or sessile organisms)
Environmental Mid -Latitude Tolerance of Deep -sea vent Diffusion and Osmosis Marine Intertidal Communities Organisms Communities Seawater poses a special problem for many marine organisms because of a difference in ionic concentration (salinity ) between the body fluids of an organism and its salt water Eury - Steno - environment. Temperature Cell walls are semi -permeable ; some molecules pass thermal thermal through, others are screened out. Diffusion is the passive movement of molecules from high concentration to low concentration . Osmosis is the diffusion of water molecules into or out of a Salinity Eury - Steno - cell. If there is a difference, or gradient, between the inside and haline haline outside of the cell, an osmotic pressure will cause water molecules to move from high concentration of water (=low salinity) to low concentration of water (=high salinity).
10 Diffusion occurs on any concentration gradient across a cell membrane, including the regulation of nutrients and waste prodcuts . Osmotic Pressure
cell membrane Cells and tissue having an ionic concentration less than the seawater they live in: hypotonic many salt water fish and marine mammals have evolved waste molecule strategies to overcome the loss of water (dehydration) from their cells Cells and tissue having an ionic concentration greater nutrient molecules than the environment they live in: hypertonic fresh water fish have evolved strategies to rid themselves of excess water from their cells diffusion: high concentration →→→ low concentration Cells and tissue with an ionic concentration equal to the environment they live in: isotonic nutrients move into the cell, wastes move out sharks, rays, and many marine invertebrates
water moves out 2 - Thought experiment SO 4 - of the cell + Cl Na Below is a fish tank which is divided into two parts; a Cl - semipermeable membrane separates the two halves. The left side contains fresh water and the right side contains salt water . 2 + An osmotic pressure exists across the membrane barrier. Ca - Na + Na + HCO 3 hypotonic cell as in marine fish HCO - Cl - 3 o o - 0 / oo oo K+ Cl 2 + 35 / Na + Ca movement of water molecules? Mg 2 + salinity outside > salinity inside which side represents the which side represents the and if we (water is more concentrated on the conditions that would affect conditions that would affect drink a salt water fish? inside of the cell relative to “salts”) a fresh water fish? salt water?
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