ecosystems in delicate balance: 7. …...lpbf/uno ecosystems in delicate balance: threatened,...

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7.ECOSYSTEMS IN DELICATE BALANCE:

Threatened, Endangered, and Introduced Species of the Lake Pontchartrain Basin

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???W HAT IS A N ECOSYST

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HO W C A N W E PRESERVE THE DELICATEBALANCE OF THE ECOSYSTEMS IN THELAKE P ONTCHARTRAIN BASIN?

Essential Questions:

W HAT IS BIODIVERSITY, AND WHY IS IT

SO IMPORTANT?

W HAT�S THE STORY BEHIND THE

THREATENED, ENDANGERED, O RINTRODUCED SPECIES IN THE LAKEP ONTCHARTRAIN BASIN?

HO W DO I M A K E A N INFORMED

DECISION ABOUT A COMPLEX ISSUE THAT

THREATENS THE ECOSYSTEM?

ECOSYSTEMS IN DELICATE BALANCE:Threatened, Endangered, and Introduced Species

of the Lake Pontchartrain Basin

OBJECTIVES:

• Visualize the conceptual units which make up an ecosystem and discuss how various organisms interact in a functioning ecosystem versus a malfunctioning ecosystem.

• Develop an appreciation for the complexities of the Lake Pontchartrain Basin’s varied ecosystems, as well as an understanding of how biodiversity (or a lack of) affects the health of an ecosystem.

• Understand the various relationships and roles of organisms in a foodchain and how these relationships can become unbalanced.

• Realize the important role each of us plays in preserving and maintain-ing the health and biodiversity of the ecosystems of the LakePontchartrain Basin.

• List several threatened and endangered species in the LakePontchartrain Basin.

• Understand the status and roles of threatened, endangered and introduced species in the Lake Pontchartrain Basin.

MULTIPLE INTELLIGENCES LEARNING ACTIVITIES:Verbal/Linguistic: Develop and verbally defend a particular point of view

formulated during problem-solving exercises.

Logical/Mathematical: Reason and propose a certain course of action in a given circumstance.

Interpersonal: Choose opposing sides to defend a current, relevant social and ecological issue.

Bodily/Kinesthetic: Construct an “ecosystem” using building blocks to represent the various organisms involved.

Verbal/Linguistic: Conceptualize the various organisms which comprise an ecosystem and learn their relative relationships.

Intrapersonal: Explain personal values regarding selected environmentalissues of the Lake Pontchartrain Basin.

Naturalist: Visit a field site, using senses to observe wetlands plants and animals; observe and collect ecological information about wetlandplants and animals; understand adaptations of plants and animalsto wetland ecosystems; participate in a volunteer litter cleanup.

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ECOSYSTEMS IN DELICATE BALANCE:Threatened, Endangered, and Introduced Species

of the Lake Pontchartrain Basin

An ecosystem can be thought of as a natural unit (e.g., wetlands, pine forests, or the entireLake Pontchartrain Basin) consisting of living and non-living parts which interact to forma stable system. Examples of living and non-living parts include plants, animals, soilchemistry, temperature, nutrient supply, etc.

Ecosystems in their natural state are finely-tuned and well-balanced.

Ecosystems support and depend upon a tremendous diversity of plants and animals.

Large numbers of animals and plants in the ecosystem indicate higher levels of biodiversity and greater complexity.

Imagine the ecosystem as a tiny city, bustling with “people”. This city has atremendous number of important jobs which need to be carried out all day long,every day. Plants convert sunlight to energy; insects convert plant matter toenergy; other animals eat insects and each other; decomposers, rippers andshredders tear everything down to make room and nutrients for new plants andanimals... All of these jobs need to be taken care of by someone...BIODIVERSITYmeans that there are many different kinds of organisms available for employment at any given time...

The Sun provides energy to Producers (green plants and algae, etc.).

Producers provide energy to Primary Consumers (herbivores or organisms that eat onlyplants).

Primary Consumers provide energy to Secondary Consumers (carnivores are animals thateat herbivores and omnivores are animals that eat both plants and animals).

Secondary Consumers provide energy to Tertiary Consumers (carnivores and scavengerswho occupy the tops of their respective food chains, like eagles or humans).

Decomposers are microorganisms like bacteria and fungi which cause a breakdown of deadorganic tissues (plants and animals), releasing their stored nutrients for re-use.

Nutrients released by decomposers are re-used by producers, starting the cycle over.

A certain amount of energy is lost in each stage of the food chain. This effectively limits theoverall length of any given food chain. In other words, at some point, the energy spent gettingfood is greater than the energy gained from the food source, so an animal becomes weaker andweaker as time goes on until death finally occurs.

Increased biodiversity provides a more stable ecosystem because responsibility for various “jobs” are shared.

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When humans interfere with delicate ecosystems, the most common result is severe disruption of natural balances which, in turn, results in greatly reduced ecosystemfunction.

When agricultural runoff and sewer discharges (unnaturally high levels of fertilizer)are emptied into Lake Pontchartrain, a dramatic increase in algal growth can be theresult. This results in turbid or cloudy water. Aquatic plants die because they can’t getthe same levels of sunlight, and algae blooms deplete aquatic systems of necessary oxy-gen.

As aquatic plants die, small fish which depend upon these plants also begin to die. Inturn, larger fish which depend upon the smaller fish also die or leave. This representsthe beginning of ecosystem collapse.

All is not lost, however!!Much of the damage we inflict upon the world around us can be lessened or even reversed if we pay attention to the little changes in ourecosystems. Each of us can contribute by reducing the amount of runoffwhich enters the Lake Pontchartrain Basin and educating others about the importance of maintaining balanced ecosystems.

“Think Globally, Act Locally.”This often-quoted expression reminds us that although our problems are global in nature, we need look only as far as ourfront door to find an ecosystem like Lake Pontchartrain thatneeds our help. It also serves to reinforce the idea that by working for better and more balanced ecosystems right here, wecan ultimately affect the health of more distant ecosystems.

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Each step in the FOOD CHAIN contains appropriate numbersof organisms

For example, there is normallya correct proportion of nutrients & sunlight to supportthe PROPER BALANCE of algaeplants

When the proportions are CONSTANT, each group efficiently feeds from the nextlower group and the chainRECYCLES itself continuously

The cycle is maintained in a BALANCED SITUATION and isunlikely to change without someform of outside interventionsuch as geological, meteorologi-cal, human induced, etc.

If one group becomes toonumerous, the chain becomes UNBALANCED

For example, agricultural runoffcreates a SURPLUS of nutrientswhich can cause sudden INCREASES in algaegrowth

Too much algae blocks sunlightfrom reaching vascular plants

Too few plants means LESSFOOD for herbivores

Less herbivores means LESSFOOD for primary consumers,etc.

As the chain becomes more and more UNBALANCED, the likelihood of ECOSYSTEM COLLAPSE is increased

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ECOSYSTEMS

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Just as plants and animals in the Lake Pontchartrain Basin are entirely dependent upon each other, more distant ecosys-tems are ultimately dependent upon the health of the LakePontchartrain Basin. The reasons for this can be traced to thecomplexities of BIODIVERSITY.

GLOBALThe rapidly accelerating loss of plant and animal life on our planet can be largely attributed tohuman population pressures and the demands of economic development.

Rainforests are cleared. Huge areas of forest are killed by pollution, and continued populationgrowth threatens countless plants and animals.

The current extinction rates from deforestation alone are estimated to be 10,000 times greaterthan the naturally occurring background extinction rates that existed before the appearance of human beings.

If the current rate continues, approximately 15% to 20% of all species will become extinct with-in the next few years.

LOCALLoss of biodiversity in the Lake Pontchartrain Basin is somewhatless dramatic than these examples, yet no less significant.

Introduced species like nutria compete with native species like muskratand dramatically increase herbivore damage to marshlands. Whereas muskrat eat only certain plant species and do not appear to be as widespread as nutria, nutria are ubiquitous and eat everything in vastareas of marshland, sometimes leaving only mudflats behind. These mudflat marsh-es are more prone to erosion than were the marshes with plants. (Refer to side story by CliffGlockner, “The Marsh’s Friend, the Muskrat,” Pages 187-188).

Fewer plant species result in fewer animals which depend upon them for food and shelter.Increased development and damage to local wetlands put increased pressure upon the biodiversity of the region.

Already some plants and animals like the Louisiana Black Bear have almost completely disappeared from the Lake Pontchartrain Basin.

Other animals and plants like the Bald Eagle or the West Indian Manatee have become increasingly rare and are threatened or endangered.

The continued introduction of alien species threatens the health and continued existence of local animals and plants.

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EXAMPLESof introduced problem plants include:

■ Water hyacinths which completely clog bayous and ponds every summer,

■ Kudzu, a tenacious vine which climbs over everything in its path and blocks sunlight from other plants, eventually killing them, and

■ Chinese tallow trees, which compete with local plants for nutrients and space.

EXAMPLESof introduced animals which are presenting problems include:

■ Nutria which eat all vegetation, and

■ Zebra mussels which are clogging water intake pipes all across the country.

“Biological diversity is the key to the maintenance of the world as we know it. Life in alocal site struck down by a passing storm springs back quickly: opportunistic species rushin to fill the spaces. They entrain the succession that circles back to something resem-bling the original state of the environment.” Edward O. Wilson,

The Diversity of Life

Increased BIODIVERSITY in the Lake Pontchartrain Basin increases the likelihood that our valuable ecosystems will continue to function properly…

Preserving HABITAT in the Lake Pontchartrain Basin preserves BIODIVERSITY

WHERE ARE OUR ANIMALS GOING?The Lake Pontchartrain Basin contains many diverse habitat types. Before humans

interfered with the Basin’s ecosystems, these habitats supported an abundance of plantand animal life and were intricately woven together into a vast web of life which supported and complemented each other.

Since humans have developed much of the land surrounding Lake Pontchartrain,these once-connected ecosystems have become isolated, and their delicate balances havebecome disrupted. As this isolation and disturbance continues, ecosystems become unableto support certain animals, and the animals become threatened, endangered, or extinct.

Threatened Species are those species likely, in the near future, to become endangered species throughout all or much of their range. The range of an animal is thatgeographic region in which all of the conditions necessary for its survival are met, e.g., temperature requirements, food supply, habitat availability, clean water, adequate space, etc.

Endangered Species are those species of animals and plants identified by governmental or international organizations as being at risk of extinction because ofhuman activity, changes in climate, changes in predator-prey relationships, etc.

Introduced Species are species native to some other part of the world which havebeen brought to an area for a particular reason, e.g., ornamental plants or fur-bearing animals. These introduced species usually have some other species which keep them undercontrol in their native lands, but lack these checks and balances when they are introducedinto a different place. Without competition or predators to restrict them, introduced speciesreproduce extremely fast and can ultimately cause an ecosystem to become unstable. Someexamples of introduced species in the Lake Pontchartrain Basin are water hyacinths andnutria. These organisms have already damaged the ecosystems into which they were intro-duced and are costing taxpayers a lot of money in an attempt to keep them under control.(Refer to Cliff Glockner’s personal observations entitled “The Marsh’s Friend, the Muskrat,”Pages 187-188, culled from a life of hunting and trapping in the marsh. These observationsprovide one man’s perspective of the traditional role of muskrat in the marshlands surrounding Lake Pontchartrain.)

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AN ECOLOGICAL BALANCING ACT

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(Refer to “ BASIN MAP WITH VEGETATION/HABITATS” in Appendix A)

MANAGEMENT AND REGULATION...Once exotic plants or animals have escaped from captivity and become established in the

wild, we, as citizens, are faced with many possible courses of action. If our response is prompt,we can often minimize the dire consequences to our precious ecosystems.

On the other hand, if we are not paying attention to the wetlands surrounding LakePontchartrain, dramatic situations can suddenly loom into our everyday lives. A perfect exam-ple of the latter situation is the current nutria problem in Jefferson Parish where nutria are eat-ing the vegetation along the drainage canals and tunneling under roads causing erosion.

■ Decision Making and Issue AnalysisStudents can assume the roles of the various agencies involved in thedecision-making process regarding threats to the ecosystem, proposing and defend-ing their viewpoints.

Viewpoints should be well-grounded in scientific fact and well-researched.

Reaching agreements about complex social issues often require a high degree ofdiplomacy and considerable amounts of compromise between concerned parties.

The educator reads the following excerpt from a Times-Picayune article datedJanuary 21, 1994 (Section A, p.1, column 3) regarding the nutria problem inJefferson Parish:

They’ve already been blamed for eating state wetlandsand sending the ecosystem into peril. Now, the rapidlyreproducing nutria are taking the rap for wreckingJefferson Parish drainage and roadway systems.

Parish officials said the open drainage canals thatcrisscross Jefferson have become havens for the semi-aquaticrodents. Thousands of nutria are digging into the canal banks,undermining nearby roadways and collapsing drainage pipesthat feed canals...

The nutria have dug holes into canal banks along VeteransMemorial Boulevard, Vintage Drive and West Esplanade Avenue inMetairie and into the banks of several canals on the West Bank. Officials said thenutria tunnels, some of which are 10 to 12 feet deep, have destabilized the banks andcracked drainage pipes that run through the banks. The burrows also have causedcracks in sections of West Esplanade and other roads near canals.

Parish Public works Director B.K. Sneed said the parish is trying to put a priceon the damage caused by the nutria.”We’re going to different parish departments to tryto quantify the problem because it affects not only drainage, but roads,” Sneed said.“It’s a big problem....” 179LPBF/UNO

The educator and students review the following model of a typical decision-making process:

SCENARIO/ISSUE ANALYSIS

Nutria have moved into suburban Jefferson Parishfrom the surrounding wetlands where they “belong”.

Nutria burrows are undermining the roadway foundations and causing extensive and expensivedamage to public property.

The nutria must be removed, but animal-rightsactivists are outraged that the nutria will be killedand insist upon further studies to determine the mosthumane methods of eradication.

■ Continue to fund studies until the problem goes away.

■ Trap nutria and release them in other areas.

■ Eat the nutria, using creative recipes.

■ Let the Jefferson Parish deputies use the nutria for sharp-shooting practice.

■ Feed the nutria poisoned sweet potatoes in the hope that this will limit population size.

■ Other

Chosen representatives make decisions using citizens’ input.

Thus, values are applied.

DECISION-MAKINGPROCESS

Situation

Problem

Values Conflict

Possible Solutions

Decision

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The educator reads the following excerpt from a Times-Picayune article datedSeptember 24, 1991, Section A, p.1, column 2) regarding the Salvinia problemacross Southern Louisiana:

Salvinia minima sparkles in the morning dew asit drifts quietly on the bayou waters of Jean LafitteNational Park.

The fine hairs of its tiny leaves hold dew in beads,catching the sun’s rainbow like so many jewels, and for ashort while it seemed like one of nature’s fortunate acci-dents.

But the beauty has proved deceptive. The diminutivefern threatens to grow into a bayou-choking, oxygen-killingpresence if not brought into check.

The plant resembles native duck weed, which, as its name implies, ducks eat. ButSalvinia, like many exotic plants that somehow escaped into the Louisiana environ-ment, doesn’t seem to be food for much of anything.

It does provide a fine habitat for mosquito larvae, and it is a troublesome andcostly obstacle to boaters, said Glen Montz, chief of the Corps of Engineers aquaticgrowth control unit in New Orleans.

The plants, which form a carpet on the surface of the water, have invaded everywaterway in the park and the shallow freshwater swamps. It has massed in layers 3to 4 inches thick in some places, making canoeing somewhat like paddling throughmalted milk.

Salvinia may be from either Africa or South America, although nobody knowshow it got here. It has lived in Florida for several years and recently spread rapidlyacross South Louisiana.

“It causes navigation problems for small boats...” said Richard Bassette, stateDepartment of Wildlife and Fisheries aquatic plants section coordinator.

It has the potential for causing more serious problems, too, he said. It can imitatewater hyacinth in blocking sunlight from the water depths. That reduces or stopsgrowth of minute plants that are the basis of the aquatic food chain.

It also can reduce the amount of oxygen getting into the water, which can killfish, Montz said. Even though no fish kills have been reported as a result of Salvinia,wading birds such as egrets may not be able to find food because of the fern.

It sounds potentially disastrous, joined with the knowledge that Salvinia hasgone from covering one acre of water surface in 1980 to nearly 6,000 acres now, Montzsaid...

...Efforts to control it include herbicides and mechanical harvesters. The Corps ofEngineers and the U.S. Department of Agriculture also are studying possible naturalcontrols, such as insects, Montz said...

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The educator guides the students through the decision-making process, allowing them to brainstorm, research solutions, and make decisions.


Salvinia are clogging navigable waterways all acrosssouthern Louisiana, especially in the LaBranche andBayou Sauvage wetlands in the Lake PontchartrainBasin.

Uncontrolled reproduction of exotic species and lackof any natural controls allow Salvinia to expandunchecked.

To remove unwanted Salvinia without using highconcentrations of chemical pesticides which may ormay not further damage fragile wetlands.


Situation

Problem

Values Conflict

Possible Solutions

Decision

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The educator reads the following excerpt from a Times-Picayune article datedMarch 19, 1993, Section B (St. Tammany), p. 1, column 2), regarding the dredg-ing of the channels through the West Pearl River.

It’s all a matter of perspective.

Up in Bogalusa, La., folks view the West Pearl River as an arteryof trade, a waterway well suited for shipping wood products andother items from the city to points across the country.

Down in Slidell, boaters, fishermen, conservationists and others have another view. To them, the West Pearl is one of St.Tammany Parish’s most treasured natural resources.

Both groups can make convincing arguments about whytheir interests should determine theriver’s future.

Officials of the Army Corps ofEngineers are trying to weigh the argu-ments and decide whether it should resume dredging the river system’s barge canal toaccommodate commercial enterprises.

The Corps has issued a preliminary environmental impact statement that supportsthe dredging. If that recommendation is accepted —and financed by Congress —year-round dredging could resume as early as April 1994, corps officials said...Restoring thebarge canal, which links Bogalusa to the West Pearl River, to its former condition isvital to Bogalusa’s economic future, the (Bogalusa) mayor (Toye Taylor) said.

But several speakers, including a number of St. Tammany Parish residents who usethe lower West Pearl River regularly, countered that dredging threatens to cause ecologi-cal damage to the waterway and the area.

“The proposed dredging could have adverse impact on a number of species, including the ringed sawback turtle and the gulf sturgeon,” said Allan J. Mueller, fieldsupervisor for the U.S. Fish and Wildlife Service in Vicksburg, MS.

“This is one of the last unaltered swamps and river systems we have left,” PaulWagner, operator of Honey Island Swamp Tours, said. “Just leave it alone.”

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The educator guides the students through the decision-making process, allowing them to explore the values conflict, brainstorm and research solutionsand make decisions.


Dredging of the channels through the West PearlRiver are proposed so that commerce may be expanded in communities to the north.

Dredging will damage extensive wetland ecosystemsin the Pearl River Basin and further threaten endan-gered species like the ringed sawback turtle and thegulf sturgeon.


Situation

Problem

Values Conflict

Possible Solutions

Decision

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ECOSYSTEM TUMBLEEcosystems are complicated places where all manner of different plants and

animals interact with each other in often unexpected ways. Frequently, when oneaspect of an ecosystem is “manipulated,” another seemingly unrelated part isadversely affected. Sometimes, if the wrong part of an ecosystem is destroyed(plant or animal), the entire ecosystem can fall apart or “crash”. This pivotalspecies is often referred to by scientists as a keystone pecies. This exercise candramatically illustrate the delicate balance between organisms in LakePontchartrain’s numerous ecosystems and even the balance between the variousecosystems.

Can You Name Some of the Ecosystems Located around Lake Pontchartrain?

PLANTS ANIMALSUPLAND FORESTS Pine, Beech, Wild Turkey,

Oak, Hickory Deer

Magnolia, Ash, Weasels, Skunks, Oak, Sweetgum Opossums, Racoons,

Deer

Bald cypress, Alligator, Tupelo gum, Nutria, Heron,Ash Boar, Deer

Bulltongue, Alligator, Palmetto, Cattail Nutria, Ducks

Bulltongue, Cordgrass Nutria, Blue crabs,Spikerush, Bullrush Egrets, Ducks

Saltwort, Hermit crabs,Smooth Cordgrass, Speckled trout, Black Needlerush Redfish, Muskrat,

Pelicans

BOTTOMLAND HARDWOOD FORESTS

CYPRESS/TUPELO SWAMP

FRESH MARSH

INTERMEDIATE MARSH

SALT MARSH

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ACTIVITY: Ecosytem Tumble

Materials:Lots of wooden blocks of uniform sizes (these can be obtained from construction sites at no cost and cut to uniform sizes)

Colored pencils to draw organisms on the blocks...or...

Lots of small photos cut from magazines which depict the various aspects of anecosystem...plants, insects, fish, bacteria, eagles, etc...use your imagination!

Scissors to cut the pictures to size

Glue to fasten the pictures to the sides of the blocks

Getting Ready:

It is helpful if the blocks have been sanded to minimize splinters.

Pictures should be cut out and trimmed to fit on the sides of the blocks (this can be anentire excercise…i.e., “find and cut-out pictures of organisms in a...[insert what type ofecosystem here]...ecosystem”). This prompts a discussion of food webs and eco-pyra-mids...

A sturdy low table is necessary, as is some clear space around it (for the falling blocks)

Directions:Glue or draw pictures of organisms onto the blocks. It can be helpful to try to pay someattention to the relative numbers of organisms (more producers than secondaryconsumers, etc.) although this is not strictly necessary.

Students take turns placing blocks on the table, producers on the bottom, then sec-ondary consumers, etc., spacing them an equal distance apart. Build an “ecosystem” byplacing layer upon layer of blocks until a certain ecosystem size (complexity) is obtained.

Now, the fun part...Students take turns removing blocks and making up a reason forthat particular animal’s (or plant’s) removal from the ecosystem. For example, a blockcontaining a picture of a clam could be removed because of extensive shell dredging.

Eventually, the ecosystem becomes less and less stable as blocks are removed. One ofthe remaining blocks will inevitably cause the ecosystem to crash...Great Fun! This canlead to many interesting discussions if students are guided through the many possibleecosystem concepts.

Alternate Suggestion: Place nothing but secondary consumers on the bottomlayer and try to determine which of these animals is the keystone species.

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The Marsh’s Friend, the Muskratby Cliff Glockner

EDITORIAL NOTE:Cliff Glockner, the author of the following piece, is a commercial hunter and fisherman who

possesses extensive knowledge of the local wetlands surrounding Lake Pontchartrain. He andhis wife Connie Glockner are featured in the video, “Pontchartrain Stories”. This kind of direct,firsthand knowledge is so vital to our understanding of the problems facing this threatenedecosystem that we have decided to transcribe his story verbatim. His information was obtainedfrom years of observation while working in the wetlands and although much of this informationis speculative and has not been scientifically validated, it serves as a nucleus of informationfrom which scientists can formulate testable hypotheses. Although we can attribute much herbivore damage in marshes across our state to the rodent muskrat, they do possess a different life history pattern than do nutria and perhaps as a result are not as widespread. It isalso likely that Mr. Glockner’s observations are particularly pertinent to the wetlands surrounding Lake Pontchartrain, given their historical vegetation patterns. While it is true thatmuskrat can and do cause ecological damage via herbivory (i.e., “eat-outs”), historically theirnumbers have been controlled one way or another, and damage was somewhat more localizedthan damage caused by nutria. Since the introduction of nutria to Louisiana’s wetland ecosystems, the damage attributed to herbivores has become increasingly pronounced.

We also felt that, while the article may not contain the style and polished nature of the professional writer, editing would diminish the overall “flavor” of the story.

As an example I am going to describe the types of marshlands around LakePontchartrain which the same principal can be applied to many of the marshes in southLouisiana during the ’40s and ’50s. These marshlands were bordered on the lake shore by anatural levee ranging from 2’ to 10’ in height above the marsh level, with an occasionalbreak by a river, bayou or pass. The banks along these rivers, bayous and passes were alsonaturally elevated above the level of the marshes, preventing most of the sheet flow. This leftthe marshes behind the banks in essence, a saucer that held fresh water. The small bayousand some of the larger bayous were restricted by a bar (mud or sand) at the mouth whichacted as a natural sill. This natural process is still evident today around the mouths of theRigolets and Chef Menteur passes. Which made Lakes Maurepas, Pontchartrain, Borgne,and the marshes of Saint Bernard and Plaquemine [parishes] some of the most productivehabitat for fisheries and wildlife in the world.

Something had to keep the process going. The dying of vegetation and turning into detri-tus was one of these processes. Most of these sediments decompose fairly rapidly and arewashed away as detritus and what is left is not compacted and not suitable for root attach-ment by plants, as is the popular belief.

Dead grass, decomposed or not, generally is washed away by high tides during stormyseasons. Other is burned naturally by lightning fires or by fires set by trappers.

There is another way these marshes were maintained and kept productive in addition todying vegetation building sediments. This was done by a little animal called the southernmuskrat. His role in nature was not only as a food source for otters, mink, coon, hawks, owls,alligators, turtles and garfish, nor only as a valuable fur-bearing animal. He also helpedmaintain the marshes to sustain a “no net loss.” A layman’s first thought when he sees amuskrat nest is that he is a destructive animal. Only through years of observing 187LPBF/UNO

these animals in their natural habitat can one learn the truth. Muskrats reproduce veryrapidly, breeding every 8 to 12 weeks. Being high on the menus of most animals and a valu-able fur are ways that the muskrat is kept from overpopulating. Other ways that muskratpopulations were kept in check are diseases caused by overpopulation and castration of maleyoung by the mother. Muskrats destroying the marshes by an eat-out were a rarity. More 3-cornered grass marshes were destroyed by eat-outs caused by geese than any other way.These birds found 3-cornered grass a delicacy. They would pull so many of the red tuberousroots of the 3-cornered grasses, that they would actually turn a section of marsh into a barrenmud bar. When high water covered these areas, the marsh would literally float off and leavea pond, which in turn made habitat for other fish and wildlife.

One acre of marsh, with a healthy muskrat population, would have approximately 50muskrat nests. These nests will range from a small nest by young muskrats weighing 25 lbs.of vegetation, mud and roots and up to 300 lbs. in the adult female nests. Nests are built withmud, roots and grass tops to form a slow decaying compost pile. The muskrats primarily eatsthe roots of the 3-cornered grass, flagging, and sawgrass from the tunnels that run beneaththe roots of the grass. In turn these tunnels aerate the soil, serve as a conduit for direct rootfeeding from rotten vegetation that is washed along in the tunnels, and stimulates new grassgrowth. The muskrat only eats the red tubers and does not destroy the root system nor does hekill the plant.

When marsh grasses are healthy, they will feed off of themselves receiving nutrients fromthe dying vegetation.

Tussocks are old rat nests formed on feeding platforms, rotting logs, wood that drifted up in the marshes and partially settled in the soil. Tussocks are a massive root system

of marsh plants with very little soil and is raised above thenormal water level of the marsh...

Due to the rapid cycle of building andabandoning muskrat nests, I believe this is how,in part, the marshes were sustained for at least

the past 1,500 years. This no net loss bynature’s own sustainably was interruptedthrough the logging of cypress and creatingpullboat runs, trappers’ ditches cut throughmarshes, oil companies digging canals and

pipelines, channelization and cutting ofship channels, opened the marshes to

direct contact with saltwater intrusionand rapid loss of nutrients and the introduction of

nutria and development of marshes by man. All of these human-induced disruptionsare causing the natural process to fail.

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ACTIVITY: “I’m a Survivor”

Objectives: Use field experiences and/or the Internet to research the plants and animals of the wetlands.

Observe and collect ecological information about the plants and animals of the wetlands.

Understand adaptations of plants and animals to wetland ecosystems.

Compare and contrast the flora and fauna of a local wetland with those of another wetland in the state, country, or world.

Prepare a portfolio of materials documenting the research.

Communicate information about the plants and animals of the wetlands.

Note: If it is not possible to provide students with a field experience, thisactivity can be conducted as an Internet research project.

Teaching Materials: Field guides (wetlands, plants, insects, fish, amphibians, reptiles, birds,mammals, etc.)

Field gear and equipment (old clothes/shoes, nets, collecting jars, plant presses, notebook or field log, permanent marker, pencils, sunscreen, insect repellent, hat, water, snacks, etc.)

Camera and film (digital, prints or slides) or video camera

Tape recorder (if desired)

Computer with Internet provider

Copies of “I’m a Survivor: Student Field Log Sheet” (Pages 191-192)

Copies of “I’m a Survivor: Internet Log Sheet” (Pages 193-194)

Paper

Pencil

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Getting Ready:Familiarize yourself with a variety of web sites about wetlands (see Appendix D), as well as with a local wetland field site, if desired.

Prepare for field trip.

Organize students into cooperative learning groups, if desired.

Distribute copies of “I’m a Survivor: Student Field Log Sheet” and “I’m a Survivor: Internet Log Sheet.”

Be sure that students are familiar with use of field guides, field equipment, and the Internet.

Describe parameters of the fieldwork, the Internet research, and the portfolio assignment for students.

Prepare wetland assignments for individual students or student groups. All student groups will research the local wetland field trip site. Refer to the Lake Pontchartrain BasinFoundation’s publication, A Guide to the Wetlands of thhe Lake Pontchartrain Basin. Assigneach group another wetland in Louisiana or elsewhere in the United States for its researchproject.

P

Procedure:Working alone or as part of a cooperative learning group, follow instructions on the “I’m a Survivor: Student Field Log Sheet” and the “I’m a Survivor: Internet Log Sheet.”

Prepare a portfolio containing documentation of your field work and Internet research on wetland flora and fauna. Include items such as:

Extensions: Have students present the results of their Internet research to the class or to other classes.

Conduct a litter cleanup of the area around the field site.

Assessment Procedures:Have students develop an appropriate rubric in class to evaluate their portfolios, based on the parameters of the project.

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• Photos, slides or video• Audiotapes• Journals• Collected specimens (any collecting

should have an absolute minimum negative impact on the wetlands)

• Drawings or sketches• Maps• “I’m a Survivor: Student Field Log Sheet”• “I’m a Survivor: Internet Log Sheet”

IDENTIFICATION OFPLANT OR ANIMAL

ADAPTATIONS TO AWETLAND HABITAT

ECOLOGICAL INTERACTIONS

Common name:

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Scientific name:

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Genus: _____________________

Species: ____________________

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Physical characteristics:

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Behavioral characteristics:

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NAME____________________________________________________ DATE_______________________

“I’m a Survivor”

Student Field Log SheetIn any ecosystem air, sunlight, water, soil, plants and animals display a uniqueecological interaction. What physical and/or behavioral characteristics helpplants and animals adapt to living in wetlands? How do biotic and abiotic factors work together for survival? It is your mission to identify as many of thoseas you can, so have your field guides handy! Complete the chart below as a recordof your observations. If you need additional space, get another chart from yourteacher or field trip leader.

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Common name:

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Scientific name:

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Genus: _____________________

Species: ____________________

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IDENTIFICATION OFPLANT OR ANIMAL

ADAPTATIONS TO AWETLAND HABITAT

ECOLOGICAL INTERACTIONS

Common name:

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Scientific name:

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Genus: _____________________

Species: ____________________

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Common name:

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Species: ____________________

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NAME____________________________________________________ DATE_______________________

“I’m a Survivor”

Internet Log SheetYou can research plants and animals of the wetlands on the Internet. Many webpages have a lot of information, but it’s not always in the same format. Use thisworksheet to help you collect and sort data from your assigned web sites.Remember to add these sheets to your portfolio! If you need more space, get additional sheets from your teacher or field trip leader.

ANIMAL INFO PLANT INFO ECOLOGICAL INTERACTIONS

Web Site Name:

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URL:

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Geographical Location:

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Common name:

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Scientific name:

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Common name:

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ANIMAL INFO PLANT INFO ECOLOGICAL INTERACTIONS

Common name:

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ecosystems in delicate balance: 7. …...lpbf/uno ecosystems in delicate balance: threatened,...

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