marine bio lectures
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Hydrothermal vents
Occur at - ocean-spreading centers worldwide
- What are hydrothermal vents
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⬢ Fissures or chimneys in ocean crust where geothermally heated water released
-undersea hot sprigs - ⬢ Dense chemosynthetic bacterial assemblage at vents
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– Autotrophs use O2 to oxidize H2S, fix CO2
– S and carbohydrates produced - ⬢ Stable isotope data suggests
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more than one carbon fixation pathway at vents and that carbon not from photosynthesis
δ13C of suspension-feeding vent clams = -32.6, Riftia = -11 and non-vent benthos = -8 - Cold seeps
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Methane oxidation pathway (coupled with sulfate reduction) is useddd by bacteria at seeps
-H2s produced and may be used.
Seeps are cold and may be found in very shallow water - How does Riftia provide the needed raw materials for its symbiotic bacteria?
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⬢ Hemoglobin binds O2 and a protein binds sulfide in the blood in the red plume
⬢ Circulatory system delivers oxygen and sulfide to tissues
⬢ Internal, symbiotic bacteria reside in the trophosome and account for 60% of the total mass of the animal - What is a reef?
- ⬢ Massive deposit of CaCO3 (limestone) produced by algae, coral and other invertebrates
- reef Importance to humans
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⬢ Reefs create harbors and protect mangroves and seagrass beds
⬢ Significant fisheries
⬢ Aesthetic appeal and tourism
⬢ Biodiversity high and chemical ecology complex
-potentially important pharmaceutical and consumer products await discovery - Reef-building (stony) corals
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Hermatypic or Scleractinian
⬢ Corals limited to seas > 20o C isotherm
-optimal 23-25 C
⬢ Light is necessary for photosynthesis
⬢ Water depth limited to 50-70 m with the majority < 25 m
Compensation depth at 15-20% of surface light
⬢ Grow fastest at 35⬰ but tolerate higher salinity better than lower - ⬢ Non-reef building corals
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(ahermatypic or soft corals) are found worldwide, but are mostly solitary
-deep water soft corals are more prominent than soft - ⬢ Growth/shape of corals varies
- – massive, branching, foliose or laminar
- Planula larvae
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⬢ A ciliated ball of cells with variable dispersal (perhaps days) before settlement and metamorphosis to a polyp
⬢ Larval settlement may require coralline algae
⬢Time to sexual maturation is relatively long (7-10 y) - Reef builders include
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⬢ Corals, sponges, erect coralline algae (a type of red algae that resists grazing due to heavy calcification) and large molluscs precipitate massive amounts of calcium carbonate
⬢ Encrusting algae in crevices cement the reef - Acanthaster planci
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Crown-of-thorns sea star
⬢ Predator that feeds by digesting away the whole coral head after everting its stomach over it - Corals and reefs threatened by
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• Overfishing – destructive techniques including cyanide and explosives
• Eutrophication- nutrients make regulation or zooxanthellae difficult and they may grow too abundant and migrate
• Global warming – corals live near their upper lethal limit for temperature - ⬢ Clupeids
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anchovies, herring, menhaden; #1 in tons
-shallow continental shelf fisher
-phytoplankton feeders
-large purse seines used
-fish meal and fertilizer - ⬢ Gadoid
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cod, pollack, hake, #2 in tons
-bottom dwelling predators
-continental shelf and shallow coastal waters
-bottom trawls
-used in fish burgers and artificial crabmeat - ⬢ Tuna and mackerels
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#4 in tons
– Top carnivores in oceanic food webs; 7-8 trophic levels below them
– Active, cruising fishes that prey on clupeids
– Purse-seine and long-line fishery
– Human consumption
– Dolphins may drown in seines although regulations have reduced mortality - ⬢ Crustaceans
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mostly estuarine-dependent shrimp
⬢ -bottom trawls cause disturbance to benthos
⬢ -TEDS and by-catch - ⬢ Flatfishes
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flounder, halibut
-shallow water fishery
-Hook and line -
What fish are most
susceptible to overfishing? - ⬢ Fish with long generation times, small clutches of eggs, and fewer spawning times are most susceptible to overfishing
- important sources of pollution
- ⬢ Nutrients, pesticides, hydrocarbons, metals and chlorinated hydrocarbons
- Poly-cyclic aromatic hydrocarbons (PAH)
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⬢ < 20% of crude oil
⬢ Toxic, mutagenic and carcinogenic
⬢ Contain C=C double bonds and from 1-6 benzene rings
⬢ Some are highly hydrophobic and long lasting in sediments, especially near contaminated harbors and industrial areas
⬢At the cellular level, PAH are a narcotic that disrupts membrane function - cytochrome p450 enzymes
- metabolize hydrocarbons