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  1. Estuary:
    • place where FW&SW-Usually a river mouth (espc in TX)
    • Can have mixing: shallow, wind blown
    • Stratification common: by temp and salitinity
    • Salinity greater deeper
    • Halocline:abrupt change in salinity
    • Coriolus force: in large estuary, tides create higher water levels on 1 side
    • Not seen in TX
    • Better developed on Us east and gulf coasts than on West coast
    • Biggest u.s. estuary is Chesapeake Bay
    • San Francisco Bay-only big west coast estuary
  2. SALINITY in estuaries
    • Can have mixing: shallow, wind blown
    • In gulf, 28% is common
    • Lower saline limit for estuaries water =7%, below is FW
    • Gradual salinity change going seaward-if have mixed estuary
  3. Mixed estuary
    Gradual salinity change
  4. Stratified estuary
    • has salt wedge
    • Area of salty water
    • In drought salt wedge may go way up stream-blue crabs in Houston
    • Flood-> goldfish in bay
    • Tend to get seasonal changes: more Fresh water in winter, less in summer
    • Isohaline line=area of similar salinity
  5. How to tolerate Salinity changes
    • Move
    • Seasonal reproductive cycles
    • Dig into sediment
    • osmoregulation
  6. Take advantage estuary salinity change
    • Anadromous: salmon spawn in fresh water, grow up in Salt water
    • C atadromous: spawn in slat water, grow up in freshwater ie AMERICAN eel
    • River shrimp: Macrobrachium
    • Many species that spawn in oceans/gulf but grow in bays and lower regions of estuaries
    • Don't go up in to full freshwater, but do reproduce in salt water
    • Blue crab, commerical shrimps
    • Juveniles in bays, adults go out
  7. Osmoregulation in estuary fauna
    • Some species just tolerate large salinity range
    • Enteromorpha
    • Osysters:Crassostrea; Osmoconformers
    • True osmoregulators have excretory sytem (Kidneys)
    • Excretion=> pump out liquid
    • So NOT THROUGH ANUS; THROUGH kidneys, uretors etc
    • Active transport involved (uses ATP)
  8. What happens in true osmoregulation?
    • Water travels from area of higher concentration to area of less concentrations
    • If outside water is salty, is less concentration
  9. Osmoregulation and Marine fish
    • Hyposaline=lesser salinity= higher water
    • Hypersaline=higher salinity
    • Salt water
    • Body fluids are lesser; SW is greater
    • Drinks SW water likely to be lost excretes slats, retains water
    • Fresh water
    • Body fluids are greater
    • Water likely to flow in
    • => fish burst if doesn't excrete water
    • Retains salts from food; gill glands retain salts
    • Fish don't osmoregulate immediately
    • Have to take time at each place to allow for switch
  10. Osmoregulation and Estuary fishes
    • Some estuarine fishes that tolerate greater range of salinity: euryhaline
    • Ie Molly fishes
    • Stenohaline:
    • Tolerates only a certain limit of salinities
  11. Euryhaline
    Tolerate greater range of salinity
  12. Common conditions in estuary
    • Usually muddy
    • From salty area going upstream, more insects
    • Intermediate parts of estuaries-insects are prime choice of for food
    • Water is turbid
    • High primary productivity
    • Nutreints high
    • Much detritus
    • Export detritus-important food source
    • How far goes-depends on how fast flow and how big river
  13. Texas
    • In texas, fw input from rivers to bays is a major source of argument
    • Fresh water ecosystmes move inland
    • Cattail marsh moves first
    • Not many woody plants (trees)
    • Many species can't migrate to reproduce
    • Many bay species are exposed to SW predators and parasites if salinity increases
    • Ex Oyster
    • Eaten by oyster drills (Stamonita)
    • Murrex snail-glomps oysters
    • Stone crab (Menippe)-don't pick up-can crush oyster shell=destroy fingers
    • Parasite: vampire snail (Boonea); carries disease MBX
    • Can have salt water invasion of coastal aquifers
Card Set:
2011-10-05 20:59:17
estuaries marine habitat

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