Akiko Ogawa’s

EFB516 Ecosystems Notes

April 10, 2001 (Tue)

Disclaimer:

These notes are my personal notes. The course instructor or TAs have no responsibility for the contents or any discrepancies between the materials presented in the classroom and these notes. You cannot use or refer to these notes to support or defend your answers on your exams. I suggest you use these notes to complement your own notes, and not to solely rely on. I would appreciate your feedback on any part of these notes that I may be misunderstanding.

Announcements:

Ø      Final exam tip - be really up on something. Dr. Hall will ask a question that will require not knowledge of all of the pieces but will require detailed knowledge of one piece. Become an expert of some aspect of estuaries as well as understand in general. (+ Writing beautifully with wit and wisdom).

Ø      Reading: Textbook 2 – Read at least first three chapters and any other chapters you like.

Lecture topic:

Estuaries (section 5)

Estuaries

·        Diatoms grow better in early growing season whereas nanoplankton do better in late growing season. Why?

1.      High run-off = high [nutrients]. Turbulence keeps them suspended and accessible to the nutrients. In summer, less turbulence = sinks.

2.      At high nutrient concentration as in early spring, diatoms have higher growth rates than nanoplankton, but at low nutrient concentration as in summer, nanoplankton do better. Evolutionary tradeoffs: Michaelis-Menten Curve. What this means in a general sense of gradients and tradeoffs of gradients? Consider evolutionary tradeoffs in terms adaptations in different points of gradients?  In summer, diatoms cannot suck up nutrients through the thick shell, but nanoplankton can do since they have high surface to volume ratio. In general we think there are physiological and energetic reasons for the broader patterns we see in the general environment.

 


·        Detritus: detritus is important for productivities in estuaries except for primary producers’.

·        If detrital food chain is important, but why it is not as important as in forest ecosystems? It’s important to protect microbes and decomposers in food chains in a forest because they critical in supporting the higher trophic levels.  Analyses of, for example, the Hubberd Brook food chain by Gosz showed that detrital components of forest food chain were more important in supporting higher trophic levels than direct grazing food chains were. Refer to Gosz et al. in the Reader. He found extraordinary amount of food that went through the forest was microbially mediated.

·        Important points made this morning for a professional ecologist:

1.      Don’t logic your way through something. Don’t do that alone. Appeal to an authority.

2.      Tradeoff examples along gradient of nutrients.

3.      In most ecosystems, it’s all about microbial food chain, not just grazing

Slides

·        Mississipi River, Louisiana: boat traffic and oil refinery. By-product of refinery blown in the air stinks.

·        Cypress swamp: “knees” sticking out of the water. Roots in anaerobic water try to take and transport more oxygen to enhance the metabolism so the plant can pick up more nutrients.

·        An alligator

·        Swamp from the air: oxbow. Cut off of meander. Rivers are dynamic and change courses.

·        “Bayou”: fresh water river going through relatively swampy area.

·        Western LA near Texas: stranded beach dune system. Important for waterfowl.

·        Gulf of Mexico map: behind the sandbars at the edge of the coast are the lagoons. What are the physical circumstances that create lagoons? – low freshwater – low river water coming through. Why we find lagoons in southern TX and estuaries farther to the north? – Southern TX latitude = around 30deg. N, where Hadley Cell air descends, i.e., less rain , less riverine input of water, thus much drier.

·        San Francisco bay: tectonic basin – graben. San Joaquin and Sacramento River running into. Unusual to find estuaries in west coast because the coast drops suddenly into subduction zone. Used to be very productive, ex. chinook salmon.

·        British Columbia coastal estuaries: mountains and a lot water coming in.

·        Cook Inlet, Alaska: has largest amount of salt marshes of the states. Largest producer of seafood with LA. Lots of Spartina, salt marshes, mud flats with algae.

·        A traditional fishing community in Nova Scotia estuary: people live on estuaries where exploitable resources exist. Great cities of the world tend be located on estuaries for transportation and food.

·        Mouth of Hudson River: used to be 350mi2 of oyster bed when first settlers came. There used to be schools of fish.

·        Industrial area on Puerto Rico estuary.

·        Graph of productivity of different ecosystems from “Life and Death of Salt Marsh” (John and Mildred Teal): Desert 1/3 (tons/dry matter/year), dry agri. 0.5  to 1.5, moist agri. 1.5 to 5, and estuaries 5 to 10, coastal 1 to 1.5, ocean 1/3. Estuaries are about 10 times more productive in terms PP than most other parts of the world.

·        Thick and tall Phragmites stand in LA: one year’s growth of plants. Grows very rapidly.

·        Water dynamics of estuary Diagram: (picture below – click to blow up): Fresh water coming in tends to flow over salt water. Some of salt water mixed with fresh water. Water movement in estuaries are bi-directional – top toward the ocean, bottom toward inland. Marin life takes advantage of this bi-directional flow. There’s selective advantage for fish to live and spend first important months in highly productive environment – grow fast, less susceptivle to predation. There are three basic strategies:

  1. Rarely used. Spawn right in the estuarie. Oyster, mame chub
  2. Spawin in fresh water like salmon, ex. New Bird Bay (?). Shads, herrings. Young that came down in the estuary have particular behavioral patterns – during the day, they go to the bottom and upstream with the inflowing salt water, and at night at the surface with fresh water. It concentrates them at the area of highest productivity. Only small vertical migration of 30 to 40m allows them to utilize much larger dynamic flow, help them maximize the capture of food energy, and help them propel their genes in the future.
  3. Most common. Spawn off-shore. Young go to the bottom. Many shell fish – blue crabs, shrimps, blue fish, and 20 to 30 species. The youngs go to the bottom and sucked in to the highly productive area.


 


·        Map of SE U.S.: continental shelf far off of the current coastline – where we had estuaries 10 or 20 thousand years ago.

·        Graph of tide range and productivity: Tide appears to act as energy subsidy for the PP. Higher the tidal range, the greater the plant production – maybe because of aerating the roots?

·        Map of North America where salt marshes are found. Mostly in Alaska. British Col, whole lot on the north Atlantic coast.

·        Food chain diagram from John Teal 1962. Studied energy flow analyses of food chain. Emphasized in importance of going through decomposer food chain.

·        Measuring Flax pond in Long Island: Dr. Hall’s project on complete carbon and energy budget.

·        Flow chart of Flax pond system.

·        Photosynthesis measurement using gas exchange chamber tube.

·        Benthic chamber for measuring benthic metabolism.

·        Graph of measurement result: respiration always exceeded photosynthesis = heterotrophic system – use more energy than it produces. Where’s the energy source come from in heterotrophic system? – From surrounding salt marshes = contribution by detrital food chain.

·        Fish production measurement device – measures the square meters of fish production.

·        Another method of fish production measurement: divide a water channel into a section with two nets, then capture whole fish in the section with net.

 

Last modified: April 11, 2001 (typos corrected on April 21)

Any comments? E-mail to akogawa@syr.edu