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59 Cards in this Set

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Measuring Algal Biomass:
4 techniques
1) Filter water sample, put filter on nutrient agar - count colonies (only 10% grow)
2) Direct cell counts - Acradine Orange or hemocytometer
3) Chlorophyll measurements - spectrophotometer
4) Chlorophyll measurements - fluorometric
Measuring Bacterial Growth
measure uptake of 3H (thymidine)
only gorwing cells incorporate, measure incorporation per unti time by scintillation counter
Measuring Primary Production
2 techniques
1) O2 consumption - meausre changes in dissolved O2 in light-dark bottles
2)14C method - provide 14C in bicarb, incubate, filter, count radioactivity on filter
Factors affecting photsynthesis
1) Light
2) Nutrients -ammonium, nitrate, nitrite, phosphate, silicate, Iron
Varies w/: depth, season, affected by latitude, water transparency, compensation depth
Nutrients & Photosynthesis
Vary with: depth, season/ stratification of water column, affected by rates of "new nutrients" and regeneration of nutrients

*Requires transport molecules*
Iron - why critical for life?
- Transport of e-
- Uptake of Nitrate
- Ferredoxin
- Nitrate reductase
- Chlorophyll Synthetase
- Nitrogenase
Ironex Experiments - Ironex I
1993 - area S of Galapogos ISlands, HNLC area
- added 2 - 200 pptril Fe to surface, followed patch w/ Drogue
- primary production increased 4 fold, stopped after 4 days
- why: iron became insoluble and sank
Ironex experiments - Ironex II
- 3 Fe applications, 3 days apart, used more soluable Fe form
- w/in 1 week phytoplankton biomass increased 30 fold
- 2500 tons of CO2 taken up before patch dispersal
- Diatoms benefited most from Fe fert.
Implications of Ironex
- Possible solution for atmospheric CO2 levels and Global warming

Remaining Q's:
- does Fe enrichment lead to transport of carbon to deep ocean?
- should we even consider fertilization of HNLC areas?
3 lake regions
Epilimnion - surface mixed layer
Metalimnion - thermocline region
Hypolimnion - lower lake region
Annual Circulation Patterns in Lakes - 3 major
1) Amixis - no circulation
2) Holomixis - when mixing occurs, entire water column mixes
3) Meromixis - mixing does not include entire water column
Amixis lakes
- no circulation - due to permanent ice cover
- found at very high latitudes / elevations
Holomixis Lakes - 4 kinds
1) Oligomictic - irregular, short duration mixing
- usually low altitude, equatorial or very deep temperate lake
- mixing occurs when warm surface water is colled by cold evening or rain & wind

2) Monomictic - one regular mixing/ yr
- Warm: subtropical (and some deep temperate) lakes that stratify in summer but mix for much of the winter
- Cold: freeze over in winter; become isothermous and mix during the summer months

3) Dimictic - becomes isotherms - mix in spring & fall (typical temperate lake)

4) Polymictic - many overturns/ continuous mixing (often shallow/ unprotected lakes in subtropic & temperate regions)
Meromixis Lakes
- dense bottom water remains stagnant & usually anaerobic
- water column divided into mixolimnion & monimolimnion separated by chemocline
Lakes classified by trophic status - 3 main
1) Oligotrophic
2) Mesotrophic
3) Eutrophic
Oligotrophic Lakes
- little or few nutrients (<300ug/L N, <10ug/L P)
- U-shaped, very deep; large,
- cold hypolimnion
- Chl a < 2 ug/L; Secchi > 5m
Mesotrophic Lakes
- moderate nutrients(300-600 ug/L N, 10-30 ug/L P)
- V-shaped, moderately deep
- moderate - small hypolimnion
- Chl a 2-5 ug/L; Secchi 2-5 m
Eutrophic Lakes
- high nutrients(> 600 ug/L N, > 30 ug/L P)
- V-shaped, shallow
- small to no hypolimnion
- Chl a > 5 ug/L; Secchi < 5 m
NATURAL process of organic enrichment of a body of water resulting from increased nutrient loading & subsequent increase in primary production
Characteristics of a Lake undergoing Eutrophication
- increased N & P conc.
- increased turbidity
- decreased Secchi depth
- decreased depth as lake fills
- loss of D O2 in hypolimnion during stratification
- decreased species diversity in most habitats
- eventual filling of lake to form semi-aquatic, finally terrestrial habitat
Cultural/ Artificial Eutrophication
-Process greatly accelerated by human activities:

- clearing land (inc runoff & nutrient input)
- agriculture (manure & fert application)
- release of untreated/ partially treated sewage into lake
- release of organic wastes (milk processing wastes)
Times scale of Eutrophication
Natural: 1,000's to 10,000's yrs

Artificial: yrs to decades
Microzooplankton - overview
- smallest & most abundant organisms
- many consume by phagocytosis
- some osmotrophic
- usually consume bacteria (50% of all produced)
- marine & freshwater
- only marine
- amoeba w/ glass/silica skelton & spines
- eat bacteria & phytoplank.
- up to 2mm in diameter
- very fragile - killed by nets
- only marine
- CaCO3 skeleton w/ spines
- consume bacteria & phyto
- some have symbiotic algae
- found in tropical oceans
- almost entirely freshwater
- multicellular
- 2 cilliated disks on anterior end: beat for feeding & motility
- eat bacteria & phyto
- feed on bact, phyto, some mixotrophic
- elongate, ranging from size from about 50 um to over 1 mm in length
- covered with rows of cilia
- Some "Tintinnids" - have "lorica" (shell)
- some "Aloricate" - soft bodied
- larval crustaceans
- mostly immature copepods
- omnivorous
Bacteria & Biomass
- bacteria usually make up 1/2 or more of the bacterio- /phytoplankton biomass
- bacterial production is about 20% of primary production
- if bacterial growth efficiency is ~ 50%, bacteria consume about 40% of primary production.
- bacterial populations are stable; therefore bacteria are being grazed at he same rate as they grow
Bacteria & food chain
- traditional oceanic food chain disproven
- replaced by microbial loop
- tiny cells eating other tiny cells
- mesoplankton not built for filtering particles from water
- major bacteria consumers must be microplankton
Microbial Loop Overview
DOM -> Heterotrophic Bacteria->
Zooplankton <- Phytoplankton

Zooplankton --> Fish & Higher
Nekton - Class Crustacea
Ex: Antarctic Krill
- important commercially
Nekton - Class Cephalopoda
Ex: squid, octapus, cuttlefish
- very fast, move by expelling water from siphon
Nekton - Reptiles
Ex: Crocodiles (alligator is fresh)
- sea turtles
- sea snakes (Indian & Pacific Oceans)
- evolved from land snakes
- young born live
- very poisonous, not
Nekton - Order Cetacea
Ex: whales, dolphins, propoises
- Mysticeti: Baleen whales - 2 blowholes
- Odonticeti: Toothed whales - 1 blowhole
- make sounds from nasal area
- sounds focused by melon & sent out
- returning sounds received - allows whale to echolocate
Nekton - Order Pinnipedia
Ex: Seals, sea lions, walruses
- 4 fins
- All but 1 species marine
- eat primarily fish & squid
- exploited commerically for oil, fur, etc.
Nekton - Order Sirenia
Ex: manatees & dugongs
- exploited for meat, oil, & hide
- Steller's Sea Cow
- First described 1741;
Extinct 1768
Nekton - Fish: Class Agnatha
Jawless Fishes: Lapreys & hagfish
- circular mouth always open
- rows of conical teeth
- cone shaped tongue
- often parasitic, some predatory (size dependant)
Lampreys vs hagfish
- series of holes/ gil slits on body
- single median nostril
- certilagenous skeleton
- certilage "cup" for brain case
- Breed in freshwater: Ammocetes larva
- burrow into sediments &
filter feed

- deepwater scavangers
Nekton - Fish: Class Chondrichthyes
Ex: Sharks, skates, rays
- cartilagenous skeleton
- descended from bony fish
- complete brain case
- heterocercal tail (spine continues into upper fin of tail)
- 5 to 7 gil slits
- Sexes very evident (both have cloaca)
- males have extension of pectoral fins (claspers)
Nekton - Fish: Class Osteichthyes
Bony Fishes
- bony skeleton
- one gill slit
- paired moveable fins
- non-homocercal tail
- 20,000 species
- commercially important
Bony fish feeding habits
- Piscivorous: prey on other fish
- Plankivorous: prey on plankton
- few scavangers
- few herbivorous
Perciform body type
- ctenoid scales
- 1 or 2 dorsal fins
- 1 or 0 ventral fins
- 2 paired fin sets (pecs and pelvics)
- pectoral fins almost even w/ pelvic
- spiny rayed fins
- found in slow flowing water
- pectoral
Salmonid body type
- cycloid scales
- pelvic & pectorals distant
- trout & salmon
- found in fast flowing water
Oceanic Depth Zones 3
1) Epipelagic Zone: <200m
2) Mesopelagic Zone: 200-1000m
3) Bathplelagic zone: >1000m
Epipelagic Zone
- <300 species
- where most common fish from
- tuna, mackrel, bill fish, snapper, eels, bass
- Large, active predators
- associated w/ areas of high primary production
Mesopelagic Zone
- Lantern fish, cyclothones, lanset fish
- small aprx. 15 cm
- plankton feeders
- diurnal migration
- have bioluminescent spots on bottom on body for camoflaugue
More on Bioluminescent spots and Camoflague
- allows for camo from preds below
- breaks up outline of body against lighter water
- dots are aggregates of bacteria (vibrio-fisherii)
- colony grows when sufficient size & adaquate energy
-fish have "blinds" to open/close spots
- some put "filters" on spot to adjust wavelengths of light emitted
Bathopelagic Zone
- fish have very large mouths to engulf large peices of food if found
- Gulper-eel, angler-fish, Rattail, Halosaur, cyclothones
- diversity great, density low
Ex: Menhaden
- use gill rakers to entrap plankton
- all fish have gil rakers - used for protection on other species
- can filter 6-7 gals water/ min
- large commercial fish, most important in bay
-fished using purser seine
- used in fish & poultry food, dietary supplements, cosmetics industry
Shark Prey Detection
Lateral Line:
- sensitive to water movement
- movement send vibration, forces water into lateral line
- sense of smell also very good
Ampullae of Lorenzini:
- on snout, detects electrical field
- Have taste buds on body surface
Fish Body Shape & swimming habits
- Very thin & elongate = acceleration

- Round/ pie plate = manuverability

- medium build, w/ narrow peduncle = cruising
- vertically elongage tail
- fusiform body: max height @ 1/3 down length of body
Temp Regulation types
Poikilotherms: body temp dictated by environment

Homeotherms: body temp independant of environment
-Ex: Tuna
- Has Rete Mirablile
Rete Mirabile
- keeps inner body blood warm by counter current exchange
- outgoing blood continuously cooled by incoming cold blood
- Incoming blood warmed by already warm outgoing blood
- Can keep core body temp 20 degs. above water temp
Sharks: lipids - stored in liver as oil
Fish: swim bladders - 2 kinds:

Physoclist: bladder independant, gas gland secretes gases from blood to fill bladder

Physostome: connected to esophagus, fish can gulp air to fill bladder in addition to gland
Catadromous migration
Ex: American Eeel
- live in freshwater as adults, spawn & spend juvenile stages in marine habitats
Anadromous migration
Ex: Atlantic Salmon
- live in marine habitat as adults, travel to freshwater to spawn & spend juvenile stages
Oceanadromous migration
Fish migrate from one portion of ocean to another
- young need food source in different location