THE RAINDROP JOURNEY Story by John Waters

The raindrop, clean and pure, flew along in a fast current until it landed in the middle of a small stream.  The rushing water carried mud and all kinds of debris.  And soon the raindrop became cloudy. (B)

The cloudy little raindrop moved steadily, and soon it was out of sight of the pond.  The river entered a woodland swamp.

Along the banks were tall green trees and thick bushes.  Some were so laden with big leaves that their branches hung over the river almost touching the cool water.  The raindrop moved along through the dark woods until it emerged on the other side.

            After the raindrop passed through the cranberry bogs and fresh water marshes, it entered a wider river.  The river was filling with water from the surrounding area. 

Water came from underground springs, or flowed from the roads and parking lots.  As the raindrop passed next to a large airport something happened!  Airports have airplanes, and airplanes need oil and gasoline to run their engines.  When it rained the night before, some gasoline and oil washed off the runways and into the river.  The raindrop, holding tiny specks of mud, picked up some oil.  The once pure and clear raindrop had an oily sheen as it journeyed along under the sun. (E)

The dirty raindrop was joined by other raindrops with oil and chemicals as it drifted through the middle of a golf course and into more woods.  Here the little river widened and slowed down.  The water was barely moving and that meant the raindrop was also barely moving.  All around were vast islands of duckweed which made the surface water a light green.  And long stemmed plants, looking like dark green strings, waved back and forth near the bottom.  Along the river banks were all kinds of green bushes, tall grasses, and leafy ferns.

Something amazing happened to the raindrop.  As it passed through the wetland it entered the roots of a lily pad.   Later, when the raindrop came out of the leaf of the lily pad, it was changed.  The lily pad had taken the chemicals out of the raindrop and made it clean again. (E)

When the raindrop reached a dam it moved very fast over the top.  It was like a tiny waterfall.  There was froth and foam and the raindrop became part of a bubble.  It bobbed its way along the fast moving and narrow river speeding over sunken logs and a scattering of rocks.

After it left the woods the raindrop moved along quietly until it reached the part of the stream where houses and stores were built near the shore.  There was a tennis ball floating nearby an empty beer can.  Both passed over a soda can lying on the bottom.  The rocks below were covered with a dark brown plant called algae.  The fresh, clean smell of the river was almost gone.

The raindrop was joined by many other smelly and dirty drops pouring from springs on both sides of the little river.  The raindrop flowed along with these new drops that landed on the ground and traveled down between particles of soil, moving slowly through the ground toward the river.  Along the way they had passed under roads, houses and stores.  People above the ground driving on the roads, visiting the stores, and living in the houses were making waste and getting rid of it.  They put in the sink, down the toilet and dumped it on the ground.  Many of the chemicals ended up in the septic systems attached to the houses.  The chemicals, along with tiny living bacteria and viruses from human waste, were picked up and carried by the raindrops coming into the river.  They all headed out to the sea. (G).

When the raindrop neared a shallow saltwater bay, plants along the banks of the little river began to change.  Gone were the many different green bushes, ferns and flowers.  There were stiff grasses such as sedges, reeds and rushes.  Cattails hovered over all of them.

CONCEPT A

HOW WATER IS RECYCLED IN A WATERSHED 

“During the night on Cape Cod it began to rain, a hard rain, and soon the raindrops soaked all the land . . .” (The Raindrop Journey P.1)

All Life Connects To Water

All water,  everywhere,   is connected.  You can see and touch water in some form – by turning on a water faucet or by looking at clouds above in the sky.  Bodies of water such as lakes, ponds, and seas are connected by waters flowing across the surface of the land or seeping down and joining the flow of groundwater underneath.  Through the change of water from one state of matter to another (gas, liquid, solid and back again) it is transported in the atmosphere from place to place.. 

Only a finite amount of water is available on earth – it constantly recycles.

As part of recycling, precipitation that falls in a watershed does several things:

-       It can travel over the surface of the land as runoff, forming streams as it goes

-       It can soak into the ground to become groundwater

-       It can flow into a coastal bay,  creating an estuary

-       It can be taken up by the roots of plants and returned to the air as water vapor from the plants’ leaves  by a process called transpiration.  One large tree will evaporate an average of a ton of water per day.

-       It can evaporate into the air from open water surfaces, including ponds, streams, wetlands and estuaries.  The larger these areas are, the more water vapor goes into the air.  Eventually, the water vapor cools from a gas to a liquid (losing heat) in a process called condensation, and forms clouds.

The water cycle begins again as the water comes back to the watershed as a form of liquid precipitation- rain, hail, sleet or snow.

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CONCEPT B

THE LAND AND ITS GEOLOGY

Much of Massachusetts and Cape Cod land surfaces resulted from glacial actions of 21,000 to 17,000 years ago.  The glacier moved down over Massachusetts from the north carrying with it large quantities of rocks and soil that it scraped and plucked from the bedrock.  Piles of glacial sand, gravel and rocks left behind formed the Massachusetts landscape of today.  These glacial deposits can be compared to a pile of snow and sand left at he side of the road after the snowplow has passed by – when the snow banks melt, the sand and gravel remain behind. 

As the glacier melted back, torrents of melt – water poured out in streams that carried ‘washed’ sand and gravel out of the glacier deposit piles, creating outwash plains.  Outwash plains are made of loose, gravelly sand.  They have wide, flat surfaces and slope gently in a downstream direction.  The average deposits are from 300 to 500 feet thick above the bedrock.

Some outwash plains, called pitted plains, contain many kettle holes, or ‘pits,’ created when ice blocks were completely or partially buried with outwash deposits.  When the ice melted, the sediments collapsed, forming depressions.  The deepest ‘pits’ in the outwash plains have become kettle ponds.

In an average watershed, 50 percent of the water falling on it runs off over the surface; the other 50 percent seeps into the ground.  However, in outwash deposit areas, including most of the Cape Cod watershed drainage or flow areas, there is little natural runoff of water.  Up to 85 percent of the annual rain and snowfall (42 to 44 inches) percolates into the ground.  Only 15 percent runs off the surface into streams.  Rain percolates downward until it reaches a depth where the water fills the spaces between particles of porous glacial deposits.  In this process, the water flow creates a saturated zone (aquifer) that drains downward to a bay or large river under the force of gravity and hydraulic pressure.

            Strong underground movement of water can be seen as hundreds of groundwater springs trickle from the banks of small streams.  These surface water streams, called gaining streams, are made up of groundwater.  Gaining streams flow faster simply because the water drainage is not slowed by sand and gravel.

          Outwash plains make excellent, efficient water supply recharge areas called aquifers (sand and gravel sediments saturated with groundwater).  Unfortunately, these same characteristics increase the potential for pollutants to enter the groundwater system.

            Human use of watersheds means less water falling on porous ground and an increase of nonporous surfaces – such as roads and parking lots which prevent rain water seepage into the ground.  Water running off these nonporous surfaces carries oils and other pollutants into streams and groundwater.

            For a short time after a rainstorm, the water in rushing streams will be muddy with soil particles and other suspended materials.  This sedimentation can be made more severe by human impacts such as housing developments, cleared land, plowed fields or tracks from vehicles in bare dirt.  Such activities destroy the vegetation that helps hold soil in place.

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CONCEPT C 

WETLANDS ARE WATERLOGGED HABITATS

Just What is a Wetland?

           Imagine standing at the edge of the freshwater wetland meadow described above in the Raindrop’s Journey.  There is no doubt that if one walked into the meadow, it would be a very wet walk.  The plants and animals living in and near a wetland are adapted for spending most of their lives with wet feet or roots.  Most scientists who study wetlands would certainly call this a wetland.  The soil is waterlogged in some places, and covered with a shallow layer of water in others fitting the description of a wetland.  Open bodies of water such as ponds, lakes, streams, rivers and oceans are not classified as wetlands by scientists.

Why are wetlands wet?

Wetlands usually lie in low areas.  Rain and runoff flow into them, keeping the ground saturated (filled) with water.  Many wetlands in Massachusetts are part of the groundwater.  In these wetlands, the top of the groundwater or aquifer (called the water table) is at the surface.  This means water from below is keeping the wetland wet, except in long droughts, when the water table drops.  Other wetlands may have clay or peat bottoms that are impermeable and hold water much as a saucer does.  These wetlands are kept wet by water from rain, rivers, streams, ponds, lakes or the ocean.

            Wetlands can also form when a beaver dams a small stream, turning meadows into marshes or parts of forests into swampland.  People sometimes create wetlands.  For example, cranberry growers may divert some water from a stream to flood a bog, or a state agency might flood an area so wildfowl have a place to breed.  Sometimes a wetland forms accidentally when construction, creation of a parking lot, or other development blocks the natural flow of water.  When development occurs, a poor understanding of water flow in the area can lead to unwanted flooding when rain or snow is heavy.

            Healthy wetlands contain a large diversity (many kinds) of plants and animals.  These plants can take up and tolerate amazing amounts of pollution.  However, when the tolerance line is crossed and a change in water flow and/or increased pollution occur, some of the more sensitive plants die.  Only the most hardy plants survive and diversity  is lost.  When some plants are lost, certain animals are unable to survive.  Gradually, the healthy wetland begins a downhill slide.

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CONCEPT D 

CRANBERRY FARMING:  EXAMPLE OF AGRICULTURAL WETLANDS 

The cranberry is a native American wetland fruit (Vaccinium macrocarpon) that was part of the diet of Native American people when the early settlers arrived.  These plants producing “them sour berries” thrive in poor soil that is unfit for most agricultural production.  They grow in abundance in natural bogs found in kettle holes lined with clay that evolved from glacial deposits.  The bogs become filled with water and decaying matter, creating an ideal place for cranberries to grow.  The bogs are supported by a surrounding network of fields, forests, streams and ponds that make up the typical cranberry wetlands system.

In the early 19^th century, the first farming attempts were made when Cape Cod settlers discovered that the kettle holes of the area were suitable for growing cranberries.  Cranberry bogs in other areas of Southeastern Massachusetts were often built on peat bogs that had been mined for bog iron.  (Bog iron, although a log grade ore, helped to establish the first iron industry in the country.)

The cranberry bog is an agricultural wetland ecosystem that appears to be used by a relatively low number of different kinds (species) of plants and animals.  Yet, recent studies (IEP Report, 1991) revealed that adjacent managed habitats – such as reservoirs, drainage channels, irrigation ditches and low brush communities – provide breeding areas, places to hide, and feeding sites for many additional species.  These uses of the land to supply water to the cranberry bogs are part of the operation of a successful cranberry farm.

According to Ellsworth and Schall, “Although wildlife diversity is relatively low in cranberry beds, diversity within the overall system is high, when compensation from the other habitats is taken into consideration.  The stud was conducted during a brief 16-day history period in May –June 1990, therefore, the number of species which actually use these wetland systems over the course of an entire year would be increased significantly.”

Massachusetts cranberry growers preserve more that 61,000 acres of open space, with approximately 13,300 acres (Cranberry Institute Census – 1991) as cranberry beds.  This vast cranberry system offers an ideal refuge for plant and wildlife species.

Environmental Issues Related to Cranberry Agriculture

            In comparison with potential development, the overall environmental impact of cranberry growing in Massachusetts is much less.  No trees are removed, no natural groundcover is replaced with pavement, and no sewage or garbage is generated.  Flow regulation and constructed reservoirs have provided protection from flood damage and added new bodies of water to the existing ones.   

            Integrated Pest Management (IPM) is a tool used by cranberry farmers to manage pests with little disruption to the ecology of natural systems.  IPM applies biological knowledge of natural cycles, natural enemies, crop management, and weather conditions to allow natural, diverse and stable systems to work for them.

            Cranberry growers are concerned about the value of environmental quality in their farming practice.  With the assistance of the Massachusetts Cranberry Experiment Station in East Wareham, and the Cape Cod Cranberry Growers’ Association, the growers have contributed time and money (two million dollars annually) to education,  research, and activities that will maintain a healthy environment.

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CONCEPT E 

WATER POLLUTION CONCEPTS 

Problems with Understanding Pollution

The educator, in dealing with concepts of pollution and contamination, must connect the unseen and the abstract to more familiar examples.  For example:

How much is a million

If we cannot see it or taste it, how do we know it is there?

How can salt or fertilizer be a pollutant?  We eat salt, and fertilizer helps things grow.  They are not poisonous.

Pollutants in the Water

Water pollution is any foreign substance in water that decreases its value for any use, including drinking water, habitat for wildlife, recreational purposes, and agricultural and industrial use.  Pollution may come from natural sources, or from the activities of people.

Water is a Universal Solvent

Mix together sugar and salt in a jar.  No matter how long we shake the jar, these two solid particles remain separate.  Chemicals in the solid state will remain separate unless water is added to dissolve the particles down to their smallest chemical form (molecules). 

Drop a spoonful of solid particles of salt or sugar into a glass of water, stir it up and it disappears – yet the seemingly clear water will taste salty or sweet.  When this happens, we know that the solid pieces of salt or sugar have dissolved or gone into solution (become part of the liquid) in the water.

In natural wet places, such as a coastal watershed system, the water contains many substances in solution.  These substances – which are carried by, or dissolved in the water filling wetlands and wet places (swamps, marshes, ponds, streams, and oceans) – have a direct effect on the plants and animals that live there.

Water as a universal solvent makes all life possible by providing essential minerals and nutrients needed by living things to grow and stay healthy.  However, water will also dissolve and carry in solution chemicals and other pollutants that destroy living tissue.

Parts Per Million and All That

Newspapers and television often refer to environmental problems such as acid rain, PCBs (polychlorinated biphenyls), road salt, and other chemicals that are pollution our environment.  In these reports, a common term is concentrations in parts per million (ppm).  For example, in fish a concentration of PCBs must be below 2 ppm to be safe to eat.  Mercury concentrations in fish must be below 25 ppt (parts per trillion) to be safe.

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CONCEPT F

OXYGEN IN WATER 

Creatures living in water, such as the trout, extract oxygen dissolved in stream water by using their gills, just as we depend on oxygen that we extract from the air through our lungs.  Still or slow-moving water absorbs some oxygen from the air above it, but only the top layers.  The bottom layers have little oxygen.  What is there is used by the respiration of animals in the mud and by bacteria working to decay plant and animal life.

The gills that the raindrop rushed through are made of many fine, thin-walled structures.  These allow dissolved oxygen to pass from the water into the blood or blood-like fluids, which then distribute the gas to the body cells.  Fish, like suckers and eels and other animals that live in bottom muds or oxygen-poor waters, often have large, efficient gills, but still need to create a current over the gills.  Salmon and other fish living in cold fast-moving streams usually have smaller or less efficient gills.

The Raindrop Journey trout is able to tolerate water up to 70 degrees Fahrenheit as long as the water is flowing quickly.  However, the trout’s gills are damaged when there is too much mud and other types of sediment in the stream.  These can clog the gills directly or irritate them into secreting so much mucus that the gill is unable to function. 

The rushing water of the stream in The Raindrop Journey story flows over the clean gravel bottom and many tiny falls, becoming aerated by the bubbles of air in the froth.  Plants growing along the sides of the banks or anchored to the bottom add oxygen to the water during the daylight as a by-product of photosynthesis.  However, at night, plants respire oxygen just as animals do, taking oxygen out of the water.  When plants die and decay, more oxygen is used up by bacteria feeding on them.  Water never contains large amounts of oxygen.  Only 23 percent of the air above is made up of oxygen.  Even the most oxygen-saturated water contains less than 1 percent making small losses or gains critical to stream animals.

Removal of oxygen from water by living organisms is a process scientists call biological oxygen demand (BOD).  Oxygen supplies are often depleted as the result of decay from heavy leaf fall in a small stream, too much logging slash, fecal matter, or increased algae growth caused by overloading of nutrients into the stream system.  For example, manure from a dairy’s waste lagoon, if leaked into a stream, can quickly deplete oxygen.  If the oxygen level is depleted, fish may die within several hours.

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CONCEPT G

WATER QUALITY ISSUES WITHIN A WATERSHED 

Water Underground

Water that percolates through the soil carries dissolved chemicals and other pollutants with it.  The water and the pollutants flow with the groundwater down to a large river or body of water – either fresh or saltwater.

Where Pollutants Come From 

All pollutants come from POINT and NON POINT sources.  The origin or “discharge” of POINT source pollution is known.  For example, a wastewater treatment facility would be considered a point source of pollution because any pollutants found in the final effluent (liquid end product of the treatment process) could be traced back to the facility.  There are very few point sources of pollution on Cape Cod.

An example of NON POINT is the airport described in THE RAINDROP JOURNEY Story.  Oils, gasoline, cleaners, and other chemicals used at the airport collect on the pavement.  When it rains, the stormwater flowing off the paved areas collects and carries along these pollutants, which then leaches or percolates into the ground.  The sources of these pollutants are multiple, thus we cannot trace the pollutants back to one specific source. 

In the past, point source pollution received the most attention because it was easier to see and identify.  Regulators wrote laws that determine the amounts of pollution allowed to be discharged from a wastewater treatment plant or commercial business.  For example, a printing plant or newspaper company’s by-product is waste ink made from hazardous chemicals.  These chemicals must be stored in a leak-proof container and sent to a hazardous waste site.  Such pollution from specific sources is beginning to come under control.

Attention is now focused on NON POINT sources of pollution, which are difficult to see, and spread over large areas.  Non point sources create most of the pollution problems.  Some other examples are septic systems, road runoff, underground storage tanks and landfills.

The study of water as it moves through the soil is called hydrology.  Hydrologists are scientists who specialize in the study of groundwater; they identify underground water flow or plumes of pollutants.  Hydrologists measure speed and direction of plume movement.

Impacts of Human Pollutants on Water Life

Good water quality, like air quality, sustains life.  Land organisms get their oxygen from the air.  Air filled with particles of dust and chemicals affects the health of living plants and animals.

Water organisms use oxygen dissolved in water.  Chemicals, sediments and bacteria are also present in water.  Aquatic animals create currents of water to move it inside their bodies, and absorb oxygen as it passes over their gills.  In some animals, the food is brought in at the same time.  In this way, pollutants enter their bodies.

Shellfish, such as quahogs, soft shell-clams and mussels, filter their food and oxygen.  Water is carried into their body cavities over the gills.  Dissolved oxygen, tiny particles of food including plankton (algae and tiny animals), bacteria and chemicals also enter.  For example, a blue mussel pumps over seven gallons of water through its body in an hour.  Much of the ingested material is taken up into the tissues of the animal and concentrates, or bioaccumulates, over time.  Any animal that eats a meal of mussels is eating everything the mussels have stored, thus concentrating pollution further.  While the mussel may not become unhealthy, the larger animal, such as a fish, or seal, or human, can be affected.  To protect consumers, regulations govern the taking of all edible shellfish.  Shellfish for sale in markets is collected from unpolluted areas and is safe to eat.

Nutrient Loading/eutrophication

 Nutrients, in particular phosphorus and nitrogen, are necessary for plant growth in both salt and fresh water.  Nitrogen is usually, but not always, the nutrient limiting phytoplankton growth in estuaries, just as phosphorus limits growth in most freshwater lakes.  However, when an overload of nutrients is introduced into a water system, it soon becomes unbalanced, and unhealthy and rapid eutrophication results.

Eutrophication is a natural process of nutrient input into a water body.  The process is very slow in nature and is most often seen in small ponds, which gradually become swamps.  However, it is accelerated near the water by human activities, many of which produce more nutrients than natural processes.

Excessive nutrient loading can be a major problem for shallow, poorly circulating bays and estuaries.  In marine waters, plant growth is usually limited by not enough nitrogen.  Therefore, slight increases in nitrogen, primarily from groundwater flows, can result in large increases in algal growth.  Sudden and massive algal blooms result in oxygen depletion and fish kills. 

Over 70 percent of nitrogen in groundwater is from underground septic systems.  Rain also contributes nitrogen, as does the natural recycling of dead plant and animal materials.  Certain shallow and poorly flushed bays, such as Waquoit Bay and parts of Buzzards Bay, are particularly sensitive to small (1-2 ppm) increases in nitrogen.

Harmful Effects of Nutrient Loading 

As plants grow, they constantly take in oxygen and give off carbon dioxide, just as animals do.  The energy needs of all living things (organisms) are met by their breaking down organic molecules (digested food) through a process called cellular respiration.  The process requires oxygen, while carbon dioxide and water are waste products.

Plants also undergo photosynthesis, which produces a surplus of oxygen during times of sunlight.  If the weather is hot and cloudy, plants use up much more oxygen than they produce, and can actually use up all of the available oxygen in the water.  The result may be a fish kill, which is now becoming an annual summer event in certain ponds.

One common effect of nutrient loading on eelgrass is fouling.  The increased nutrient acts to overfertilize small algal growths on the blades of the eelgrass.  Algae, because it is a simple collection of single cells, grows faster than eelgrass in an overfertilized nutrient loaded situation.  Soon the eelgrass blades are covered with fuzzy growths called epiphytic growths.  Such growths prevent sunlight from reaching the eelgrass, and weaken the entire eelgrass bed.

Floating microscopic algae, called plankton, can also become so abundant that sunlight cannot penetrate to the bottom of the shallow bay.  Large algae seaweeds, such as Cladophora or Gracilaria, respond to the nutrients, growing in large sheets or massive clumps that smother the bottom.  Dying seaweeds, in turn, use up oxygen and contribute to the oxygen depletion.  When seaweeds die, the nutrients they contain are released into the water, but are immediately taken up by other plants, increasing the nutrient load in the system. 

Biological Pollutants

Biological pollutants are tiny living animals and plants that may be harmful to humans.  Pathogens are living forms causing disease or infection in people; those that do not harm people are nonpathogens.  Biological pollutants include viruses, bacteria and protozoans.  Waste from septic tank disposal systems and public package wastewater treatment plants have large numbers of these biological pollutants.  Nearly all of these organisms are harmless (non athogenic) to people, but some are harmful (pathogenic), and pose a threat to humans.  Bacteria and protozans are usually removed if the groundwater level is at least four feet below the bottom of the septic system.

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CONCEPT H 

OVER THE WEDGE:  WHERE FRESH AND SALTWATER MEET 

The Wedge

The wedge is the point where saltwater from the ocean meets with freshwater from the land.  As the two kinds of water come together, an actual wedge is formed; the incoming tide is pushing the heavier, denser saltwater against and under the lighter, less dense freshwater.  The plant and animal life in the freshwater portion of a watershed changes at the wedge.  It is here, over the wedge, that an estuary begins were a river meets an ocean and the pulsing tide is forever mixing freshwater from land with saltwater of the ocean.

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CONCEPT I

WHERE RIVERS MEET THE SEA – THE ESTUARY 

What is an Estuary?

An estuary first begins where a river meets the ocean, and the tide mixes freshwater from land with saltwater from the ocean.  Here, bays, inlets, lagoons, tidal marshes, sandy beaches or rocky shores are formed.  The lowland area surrounding the estuary is known as an estuarine zone.

Plant and Animal Life

Animals and plants living in an estuarine zone find a harsh environment.  There are rapid changes in temperature, salinity, currents and water level changing daily and seasonally.  The change depends on the amount of freshwater flowing in from the watershed, the shape and depth of the bay, and the difference between high and low tides.  Salinity in an estuary varies with the tidal cycle.  High saline water pours into an estuary on a flood tide resulting in the highest salinities.  The extent of salinity also depends on the season.  During a spring freshwater runoff, the wedge of saltwater is pushed down the river.  During low river flows in the summer and winter, the salinity wedge extends for greater distances upriver.  High and low tides also depend on the lunar cycle with highest tides (spring) occurring during the full and new moons.  Direction and strength of wind also influence the movement of tidal saltwater in an estuary and up its inflowing rivers.

 Temperature, as well as tide, varies daily and seasonally.  In summer and fall, the freshwater inflow is warmer than the ocean; therefore; the temperature is warmest in the upper estuary and coldest in the low estuary with the temperature varying with the tidal cycle.  In winter and spring, the freshwater inflow is usually colder than the ocean – making the winter temperatures opposite to those of summer.

A Nutrient Trap and Marsh Maker

In contrast to the many kinds of vegetation growing along the freshwater stream, only a few types of plants can survive in the border between sea and land.  Marsh grasses are able to grow in oxygen-poor mud and peat, every changing temperatures, and tidal seawater flooding twice every 24 hours.  They have adapted to this ever changing environment, with specialized glands to take in saltwater and get rid of the excess salt.  A system of tubes in the marsh grasses carries air to the parts of the plant that grow underground and under water.

Another significant characteristic of the estuary is its role as a ‘nutrient trap.’  The balance of forces between river flow and tides tends to slow the passage of materials and prevent total flushing through the river mouth and out to sea.  A ‘trap’ is formed between the two opposing water forces where a large collection of dead plants and animals, as well as suspended materials, is built up.  The materials eventually settle and create large shoals that become the foundation for formation of salt marshes and tidal flat communities.

Many Meadows of the Estuary

The marsh grasses and tidal flat eel grasses grow and catch or ‘trap’ more sediments and detritus.  Animals and bacteria feed upon these materials, breaking down organic matter to nutrients in a form that fertilizes the plants of the estuary – nature’s perfect recycling system.

The most important but often overlooked plants are the single – celled algae (often called microscopic plant plankton).  Large familiar algae growing in shallow coastal water, sometimes attached to rocks and pilings are called seaweeds..  At times the combination of warm water, dissolved nutrients coming down from the watershed, and sunlight promote explosive growth of all kinds of algae – the water becomes dark green with single cells of plant plankton (phytoplankton) and choked with massive drifting beds of the larger seaweeds.  Too much growth, too fast, creates great stress on all life in the estuary, resulting in unwanted changes in the natural system.  Short term stress can mean sudden ‘kills’ of oxygen-dependent swimming animals such as fish, crabs and shrimp; and long term stress is signaled by loss of diversity of species in the system.

Animals Must Adapt to Life in Fresh and Saltwater

The open ocean animals have salt concentrations within their bodies that are similar to surrounding seawater.  These animals do not normally experience conditions that would produce water balance problems.  But estuary animals, who also have salty fluids in their bodies, must adjust to the alternating high and low salinities of the estuary.  Otherwise, their body cells would take in a great amount of water when they encounter water low in salt.  If an animal cannot control its water balance, it will dies; the tissues and cells swell up and fall.  Estuarine animals have an extraordinary capacity to adjust to wide ranges in salinity.  For example, sea run trout, herring and shad are anadromous fish that are able to withstand the transition from seawater to freshwater.  Each animal spends the early stages of its life cycle in freshwater streams and most of its adult life in saltwater.  A reverse example is the catadramous. American Eel which hatches in the tropical waters of the Sargasso Sea and then migrates to estuaries.  In the fall of its third year, the willow leaf-shaped larvae metamorphoses into a transparent Elver and “smells” (by chemoreception) its way to freshwater streams, where it completes its development into an adult eel.

Impacts of Us on an Estuary

Many forces can change the structure and change the environment of an estuary.  Hurricanes or a harsh winter are among the natural events to which the estuary system has always adapted.  But in the last 300 years the agricultural, social and industrial activities of humans have created unnatural conditions that could destroy the diversity and productivity of our estuaries.  We have introduced new substances into the estuary system through the rivers from the land and directly into the ocean.  Some of the substances, or pollutants, are trapped in the muds and estuary wetlands; others are transported into the open ocean.  Life in a polluted estuary is under stress; the most sensitive species of animals and plants die first.  These creatures are the “canaries” of an estuary.  Their death is a signal that the natural system is changing.

Scientists are recording and studying the way pollutants come into and circulate through estuary systems.  These records are of great use to those responsible for the management of estuaries as a resource.  Records of present-day and past pollution allow us to estimate the future and take steps to make the choices and changes required to keep all estuaries places we will want to live and visit.

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CONCEPT J 

DIFFERENT ENDINGS FOR THE STORY DEPEND ON US

MYSTERY OF THE DEAD FISH

By:  John F. Waters

One hot summer day, in August 1988, at a harbor along the shores of Long Island, New York, flounder were seen jumping out of the water and landing on the beach.  At the same time, long, thin marine worms poked their bodies out of the mud and water trying to leave the bay.  Crabs left the salt water by climbing up thick ropes dangling from piers.  It was a strange sight, and some people decided it was an easy way to catch some fish.  So they gathered the fish off the beach and took them home to eat.  Everyone was puzzled by the mystery of why the fish and the other little animals left the salt water to die.

Within a few days, at Waquoit Bay on Cape Cod in Massachusetts, hundreds of flounder, pipefish, and thousands of small shrimp died in the shallow saltwater bay and were washed ashore.

It was important to find the answer to the mystery of what was happening to the animals in the Waquoit Bay estuary and the harbor on Long Island.  Both bodies of water were alike -  they are estuaries.  Estuaries are partly enclosed bays on the coast where freshwater rivers flow into the salt water sea.  In shallow bays, the two kinds of water mix and become brackish.  Estuaries are places where much of the seafood we eat is born and lives.

When the fish kill was discovered in Waquoit Bay, several estuary scientists from the Woods Hole Oceanographic Institution were called to look for clues and find an explanation.  After collecting information and talking with people living along the shore, the scientists offered a solution to the mystery.

The scientists knew that fish live because they take in oxygen dissolved in the water through their gills.  Humans and many other land animals use lungs to get oxygen from the air.  Oxygen is needed for fish, shrimp, crabs, and humans to live.  The scientists thought that the fish and other animals were not getting enough oxygen.

What happened to the oxygen?  Some oxygen mixes into the water from the air as wind blows over the surface.  When water is warm in the summer, it cannot hold as much oxygen as the cold water during the rest of the year.  Water changes its temperature very slowly.  As the change takes place, animals either leave the estuary in the summer or are able to adapt to less oxygen in the water.  The scientists decided that very warm water (75 to 80 degrees F) in the estuary during the fish kill was not enough reason for the fish to die.  They had to look for other reasons.

 Oxygen also comes up into the water from plants living in the water, which produce it during the daylight.  Most plants living in salt water are algae.  Unlike land and freshwater plants, algae are simple, floppy plants without roots living in water.  There are two major kinds of algae:  (1)  the larger “seaweeds,” like brown kelp and green sea lettuce that we see washed up on the beaches or attached to rocks, and (2) very tiny, microscopic floating plankton, which are made up of one cell or a chain of cells.

Algae, like all plants and animals, need oxygen to live.  During daylight hours, algae use energy from the sun to produce extra oxygen – a process called photosynthesis.  The extra oxygen is dissolved in the water.  Animals in the water depend on it to live.  If the algae stop adding oxygen to the water, the animals that depend on it may die.

The scientists learned that just before the fish died, there were six days of cloudy weather with very little wind.  The algae were using more oxygen from the water than they were making.  At the same time, the fish, crabs, and shrimp were also using oxygen.  On each day of calm, cloudy weather, more oxygen was being used by plants and animals that was being added to the water.  Also with no wind, the bay water was not dissolving as much oxygen from the air.  For the same reason, fresh water flowing into the bay floated on top of the salt water because there were no winds or waves to mix the two.

All the conditions above happened as a part of a natural cycle.  Small fish kills are expected each summer when the conditions just described all happen together.  The scientists wanted to know why the Waquoit Bay fish kill was much larger than normal.

When scientists met and compared their research, they discovered that the fish kills all along the East Coast were happening more often, and greater numbers of animals were dying.

A third problem was found to contribute to the death of the fish.  It is a human problem.  Estuaries are beautiful places and so many people want to live near them.  Each home on the watershed of Waquoit Bay has a septic system to get rid of waste.  Rain and snow falling on the watershed sink into the ground, flow under and around the septic systems, and eventually reach the estuary.

Human waste and fertilizers contain nitrogen.  Nitrogen is a necessary nutrient that helps plants grow.  In the spring, the water entering Waquoit Bay carries a lot of nitrogen in the form of natural dead and decaying plant and animal materials.  The wastes of people add much more nitrogen.  In the summer, nitrogen inputs increase because even more people are living near the Bay.