Onondaga Lake Trophic Structure Or

Who’s Eating Whom

So what?  Why should you care about trophic structure?

We humans do amazing things.  But sometimes, we wipe out specific organisms from communities in the process.  We change ecosystems around so that they can no longer support edible white fish, but rather mercury-laden carp.  How do these structural changes affect ecosystem functioning?  Too much attention is given to issues of bio-diversity, but loss of trophic levels is what we should really be worried about.

So what?  Why should you care about trophic structure?

And how do these ecosystem structural and functional changes affect the people, the community, the economy that depended on those ecosystems?  By understanding the trophic and energy levels needed within a community, we can understand how to respond to changes in our world (that we have mainly caused ourselves).  Through this understanding we hopefully can protect organisms (including humans) and ecosystems better. 

Trophic = ? of or relating to nutrition or

nourishment

Question: Is Onondaga Lake

Oligotrophic

Mesotrophic

Eutrophic?

Eutrophic: the process by which a body of water becomes enriched in dissolved nutrients (as phosphates) that stimulate the growth of aquatic plant life usually resulting in the depletion of dissolved oxygen.

The trophic level of a creature is a  description of its position in a hypothetical  food web for the community it lives in.

Onondaga Lake food web

http://www.lake.onondaga.ny.us/ol33082.htm

Trophic Level

Activity Type of Organisms

1 primary producers

autotrophs

2 primary consumers

herbivores

3 secondary consumers

carnivores, parasitoids

4 tertiary consumers

higher carnivores

•Producers are often called autotrophs because they can produce their own food, or nutrients (fixed carbon) . They utilize an energy source, such as light or sulfate, to fix inorganic carbon into organic forms  that are available for consumption at higher trophic levels. In an aquatic ecosystem these are called phytoplankton and include such species as diatoms, which we call algae.

• Consumers are divided up into several levels themselves.  Primary consumers feed directly on the primary producers.  Secondary consumers feed on the lower-level consumers and possibly the producers as well.

• Consumers are also known as heterotrophs. They must take in organic carbon in order to synthesize ATP.

• Consumers  include at a more finite level categories like herbivores, carnivores, and detritivores (feed on detritus).

Adenosine 5'-triphosphate (ATP)

• is a multifunctional nucleotide that is most important as a "molecular currency" of intracellular energy transfer. In this role, ATP transports chemical energy within cells for metabolism. It is produced as an energy source during the processes of photosynthesis and cellular respiration and consumed by many enzymes and a multitude of cellular processes including biosynthetic reactions, motility and cell division.

So, how do we measure trophic structure?

  If an ecosystem is to thrive, there have to be enough producers to sustain the consumers.  Otherwise, the consumers would starve.  How do we describe how much we have of the producers and consumers within an ecosystem?

Ecosystem TypeNet Primary Productivity

(grams meter -2 year-1 )

Swamps and Marshes 2500

Coral Reefs 2000

Tropical Rain Forests 1800

Estuaries 1800

Deciduous Temperate Forests

1250

Boreal Forests 800

Savannas 700

Temperate Grasslands 500

Tundras 140

Deserts 70

Production of energy per unit Biomass Ratio

0.042 Forests (due to dead biomass of wood xylem)0.29 Other terrestrial autotrophs17.0 Aquatic and marine autotrophs

Aquatic systems have what we call a high turnover rate of production.

Habitat Net P (g m-2yr-1) Biomass (g m-2) Turnover Time (yr)

Tropical Forest 2200 45000 20.5

Temperate Forest 1200 30000 25

Tundra 140 600 4

Cultivated Land 650 1000 1.5

Marsh 2000 15000 7.5

Desert 90 700 7.8

Open Ocean 125 3 0.02

Algal Beds/Reefs 2500 2000 0.8

Estuaries 1500 1000 0.66

Lakes / Streams 250 20 0.08

Primary productivity: amount of light energy converted to chemical energy (in the form of carbohydrates) by autotrophs (green plants and algae) per unit time (photosynthesis).

Gross Primary Productivity: total amount of energy producers make.

Net Primary Productivity: GPP minus the energy used by plants for respiration.

Secondary productivity both gross and net: productivity of organisms that consume biomass (consumers).

What abiotic and biotic factors are influencing primary productivity in Onondaga Lake?

What abiotic and biotic factors are influencing secondary productivity in Onondaga Lake?

So what is the trophic structure and trophic state of Onondaga Lake now vs. 1800?

Are there any limiting factors to primary or secondary production in Onondaga Lake?

What is fall turnover? What is its effect on the fish community?

Based on its size according to Tango and Ringler how many species should this lake support? Why are there more than expected?

What has happened to fish species richness and eveness in Onondaga Lake over time?

Why?

What improvements to sewage effluent have been forced on Onondaga County by the Amended Consent Judgment. What is the expected impact of these on the lake’s trophic state?

The ACJ is designed to improve the water quality of Onondaga Lake and achieve full compliance with state and federal water quality regulations by December 1, 2012. The ACJ specifically includes a listing of more than 30 projects to be undertaken over a fifteen (15) year timeframe. The ACJ describes the intent of each project and sets time schedules for specific work related to each project to be completed (minor and major milestones). These milestones relate to such activities as completion of environmental review, start of construction and commencement of operation.

The ACJ projects can be divided into three main categories:

•Improvements and upgrades to the County's main sewage treatment plant – METRO.

•Elimination and/or reduction of the impacts of the CSOs on the lake and its tributaries.

•A lake and tributary monitoring program designed to evaluate the impacts of the improvement projects on the water quality of the lake and tributary streams.

Patricians of the Great Lakes, lake whitefish were long prized for the delectable quality of their meat. In 1836, a scientist in the field wrote, "We can say from personal experience that a diet of whitefish alone, with no other food, can be eaten for days without losing its appeal."

Bluegills are quite common in warm-water shallow weedy ponds, lakes, and slow-moving streams. They seems to prefer the weedy shallows near shore. Diet: Bluegills feed primarily on small aquatic mollusks, worms and immature and adult insects. They also infrequently consume vegetation.

Easy to catch, bluegills make a good pan fish. They are often the first fish that a young fisherman catches.

http://www.womenanglers.us/BlueGill.html

Nearshore transparency results are affected by wind, waves, precipitation, and algae. Average results can be highly variable from year to year; consequently, a long monitoring period is needed to detect trends in nearshore transparency.

http://www.ongov.net/WEP/wepdf/we15d.pdf

Indicators of Progress: Is the Lake Safe for Water Contact Recreation?

Bacteria Level Monitoring

Hydrogen Sulfide H2S is produced under anoxic conditions when bacteria break down plant and animal material, often in stagnant waters with low oxygen content such as bogs and swamps.

http://www.sodaash.com/about/0,5373,1000073-_EN,00.html

Solvay Ammonia based process

                                                                                                                                                                                                                  

Tuesday, 18

September 2007