Habitats & Adaptations

The oceanic habitats support a great diversity of life and ecosystems (Ocean Literacy Principle #5)

Wetlands are flooded ecosystems that specialize in oxygen-free processes while providing a habitat and protection for many species of fish, birds and insects.  The vegetation in a wetland area is specialized (adapted) to the unique environment as wetlands are inundated with water most of the time.  The animal residents have their own unique set of adaptations that allow them to permanently reside, migrate through or reproduce in wetlands, making the wetland a vital ecosystem for thousands of plants and animals.  Wetlands also provide ecosystem services , goods and services that benefit and sustain us, such as stabilizing our shorelines, recycling of nutrients, food and material sources, recharge the groundwater aquifers, clean polluted water and more. 

 There are many different sizes, shapes and types of wetlands and each differs based on the location, soil type, vegetation and water chemistry.  However, to be classified as a wetland all wetlands will have three unique properties: the primary plant population is hydrophytes, the soil is hydric, and the substrate is saturated with water the majority of the time.     

The frequent or continuous flooding with water creates hydric soils.  Hydric soils are formed and identified by ponding water, complete saturation or flooding in an area long enough to create anaerobic conditions (little to no oxygen) in the soil. Under normal growing conditions this would not support plant life but hydrophytes (water plants) have special adaptations allowing them to flourish in such conditions.      

Simply put, wetlands are areas where the water covers the soil for varying lengths of time throughout the year.     

Learning Objectives:

  • Demonstrate a general understanding of the wetland ecosystem components (aquatic, terrestrial, avian & physical)
  • Distinguish between identified residential communities that call wetlands home
  • Evaluate and explain flora and fauna adaptations that lead to the success of species 

Analyzing Adaptations Flora and Fauna in Wetland Habitats: Species Found in Wetlands

Wetlands are home to a variety of species – some staying their entire lives, some stopping over to rest and refuel as part of a longer journey and others for only a portion of their lives.  We will discuss three distinct types of animals that can be found in wetlands.  These three categories contribute to the unique biodiversity of a wetland, each one playing an important role in the function of the ecosystem.

A healthy ecosystem is home to a variety of species that are intertwined with each other as well as the physical environment (soils, elements).  Biodiversity takes into consideration the greater the number of different species and number of individual within an ecosystem.  A  biologically diverse ecosystem is more resilient and healthy. 

Year-round Residents

When it comes to year-round species, wetlands support many insects, reptiles, amphibians and fish but birds really thrive in this ecosystem.  Over 1,900 bird species in North America use wetlands at some point during their lifetime but 138 are wetland dependent.  Spoonbills, herons, duck, geese, swans and egrets (to name a few) are built for life in the wetlands.  Using the vast open air to travel, the water for fishing and the land for nesting, these birds make use of all the resources available.  The richly diverse web of animals and plants that thrive here, allow for foraging and protection even through the winter months.  Wetlands are truly the place where birds grow and flourish. 

Migratory Species

As discussed previously, wetlands have permanent year-round residents however, protecting and conserving our wetlands has the largest impact on the migratory bird species dependent on the land.  The species that depend on the wetlands as a place to overnight or stay for a few days to rest and refuel for the rest of the journey.  They depend on the fish, amphibians,  insects and crustaceans for fuel for continuing their journey of which can be thousands of miles.  The Solitary Sandpiper will winter in South America near the Amazon basin and fly north to breed in Canada! 

Nursery Grounds

Wetlands are ideal nursery habitat for a large variety of species including waterfowl, fish, invertebrates, mammals, amphibians, insects and reptiles providing abundant food sources and hiding spaces.  Many commercial fish and shellfish depend on the ecosystem to raise their young.  The interconnected roots and plants provide hiding spaces for juvenile species from predators  and protection from storm wave energy.  Did you know the larvae stage of the famous blue crab of the Chesapeake Bay are an important part of the plankton community of the bay area? 

Flora and Fauna Adaptations

Wetlands are the link between aquatic and terrestrial ecosystems so it stands to reason we would see a unique set of plants not completely able to survive submerged underwater nor able to survive on dry land either. They support a variety of photosynthetic  plants (hydrophytes) that are adapted to thrive in wet conditions. Likewise, we also see adaptations in the animal species that live in the area. Waters in wetlands can fluctuate in salinity, temperature and depth daily, which creates challenges for the animals that call it home.

Flora Adaptations

There are specific adaptations unique to plants that make life in wetlands easier  include adaptations to the root systems, the bark, the leaves and the reproduction of the plant.     

Root systems of these aquatic plants have special adaptations that allow them to gain the oxygen necessary and still live in hydric conditions.  Most of the changes in the roots include adventitious root systems and shallow roots allow the plant to exist in persistent wet or soggy conditions while  providing stability for the plant to grow and a means of collecting sediment and particles from the water as it flows in and out of the area.  Without access to the oxygen necessary to carry out normal plant functions, the shoots (stems) have developed a few ways to obtain oxygen through elongated stems and aerenchyma, special air pockets inside the stem that deliver oxygen to the roots. This is like scuba diving in the plant world! 

Fauna Adaptations

The animals that live in wetlands have adapted to daily changing conditions, living in, on, or around the water all the time. The shallowness of the wetlands paired with the daily tidal changes often changes the temperature of the water, which will then affect the water’s ability to hold oxygen. Stagnant water may contain less dissolved oxygen (DO) and therefore fish and crustaceans living in a wetland without much tidal flow, have special abilities to extract the available oxygen.  Some fish species have specialized gills, breathable skin and higher concentrations of hemoglobin.

Key Vocabulary

Ecosystem Services
Flora                                                Gymnosperm                                Hemoglobin                  Hydrophyte
Soil Profile

Environmental Importance

The ocean ecosystems made the Earth inhabitable (Ocean Literacy Principle #4)

Wetlands are highly productive ecosystems that play a vital role in providing many essential ecosystem services such as purifying water, protecting coastlines from damaging storms, providing habitat for many different species and much more.   

Although the Earth hasn’t changed in size, it is now easier than ever to purchase goods from around the world. Many of the products we buy (and sell) are delivered to us by means of ships, trains, planes, cars and trucks.  The transportation of goods has created the need for more warehouses and roadways and decreased the amount of open green space.  These impervious surfaces increase the amount of agricultural and chemical runoff that makes its way into streams and rivers that eventually empty into wetlands before reaching the ocean.  Wetlands play a vital role in decreasing the amount of chemicals and pollution entering the open ocean due to the presence of plants that specialize in removing or using chemicals.   

These plants not only purify the water, they provide protection from storms that come ashore battering the shoreline. The roots structures act as a mesh that provides support for sediment and sand, keeping it from washing away.  Another role the roots play is in providing protection for small or juvenile species!   Many species depend on wetlands for part, if not all, of their lives.

Learning Objectives:

  • Identify 3 ways that wetlands are environmentally important
  • Compare wetland plant species, the chemicals they reduce and their adaptations
  • Explain the significance of reducing storm surge
  • Comprehend the significance of wetlands as a nursery

Analyzing the significance of wetlands functions in the global environment  

The environmental significance of wetlands and the study of wetland plants has become an area of science that has grown significantly in the past decade.  The more we learn about these marvels, the more we understand the role they play and their importance in helping to reverse or stop the results of global climate changeThere are many environmental important services wetlands perform including purifying water, carbon sequestrationmitigating erosion and sustaining biodiversity.   We encourage you to dive deeper into the many other ecosystem services wetlands fulfill in your area. 

Purifying Water: The Kidneys of the Land

As water flows into wetlands from rivers and inland, the hydrophytes (plants) slow down the flow of the water allowing sediment to drop out of the water column and settle on the bottom.  This not only clears the water of excess sediment (cloudy water decreases plants ability to photosynthesize and filter feeders like clam's ability to eat!) but also removes potential toxins from the water column.  These toxins/pollutants become locked in the sediment layer and essentially are removed from harming plants and animals.  

Nutrient Cycling

The hydrophytes also play a role in recycling nutrients back into the environment.  During the growing season, nutrients such as nitrogen and phosphorous are taken up by the plants through their roots and leaves and through photosynthesis, the nutrients are converted into food sources.  When the plant dies back in the autumn, these nutrients are released back into the environment continuing the cycle.


Carbon Sequestration

Wetlands capture (store) carbon dioxide from the atmosphere through the process of photosynthesis.  Known as blue carbon, aquatic plants remove it from the atmosphere converting it into simple sugars (food) used for growth and oxygen, a by-product given off.  When plants die and are broken down by bacteria, the decaying material, including the carbon is stored in the sediment, essentially locking it away for many years. 

Mitigate Erosion: The Ocean Eats the Land

Wetlands are also very important protectors of coastal shorelines from storms  by attenuating (reducing) wave energy and absorbing storm waters thereby reducing the destructive effects on the shoreline.  Some wetland ecosystems have been recorded decreasing storm surge by 50%!  The deep roots of wetland plants help to stabilize shorelines by holding the sediment/dirt in place while the leaves help to reduce erosion by slowing the flow of water.  Wetlands act like a big sponge soaking up excess water from floods and storm surge.  They then slowly release the water allowing time for the water to seep into the ground, recharging the groundwater aquifers and reducing the amount of sediment that is washed away.


Biodiversity Super Systems

Wetlands are highly productive ecosystems with intricate food webs that support countless species of fish, birds, shellfish, mammals, reptiles and amphibians.  So many different species rely on wetlands for their survival, with approximately 43% of the USA’s endangered or threatened species’ survival connected to wetland ecosystems.  Over 50% of migratory birds use wetlands as an important stopover to rest and refuel before continuing their journey.   Many species of fish rely on wetlands as spawning sites and nurseries where juvenile fish can grow and thrive in a relatively protected area.  Wetlands are also a source of recreation and esthetic enjoyment for humans whether canoeing through the waters, bird watching or fishing.

Want to learn more about Biodiversity?  Watch our short videos lesson on the importance of Biodiversity!

Key Vocabulary

Attenuate                    Biodiversity
Blue Carbon
Carbon Sink 
Ecosystem Services
Food Web
Soil Profile                      Spawning
Substrate                      Threatened


The Changing Climate

The ocean is a major influence on climate (Ocean Literacy Principle #3)

For centuries humans have depended on coastal habitats as the ecosystem services provided by wetlands played a vital role in the success of the first settlers.  The fashion in which humans and wetlands are intertwined has too often led to overuse, pollution and destruction of wetlands as our actions influence and depend on these unique ecosystems. As civilizations moved inland away from the coast, we depended less on wetland for necessities including fishing, food and materials and more on the need for roadway construction, farms and industrial sites.  

Wetlands are amazing ecosystems when left alone – without human interference – can adapt to changes in climate including rising seas, temperature and precipitation fluctuations. However, as the human population continues to exponentially grow, so does the need for food, housing, waste management and natural resources.  Thus, we have begun to overload the natural balance and push the earth closer to the tipping points. 

The global human impact on wetlands, directly or indirectly, has led to a loss of more than 50% of the world’s wetlands and with it the ability to mitigate climate change including other free ecosystems services such as environmentally friendly water filtration and carbon dioxide sequestration. 

Learning Objectives:

  • Identify 3 ways that wetlands are environmentally important
  • Compare wetland plant species, the chemicals they reduce and their adaptations
  • Explain the significance of reducing storm surge
  • Comprehend the significance of wetlands as a nursery

Anthropogenic Actions and Climate Change

Human activity has altered the climate through increased input of chemicals into the environment, decreased pervious surfaces, increased atmospheric greenhouses gases and loss of critical habitat.  These actions increase the earth’s global average temperature, alter the amount of precipitation and runoff as well as speed up the melting of land and sea ice of which all indirectly cause sea level to rise and increase the inundation time and depth of wetlands.   

The adverse effects of human impacts are not always direct, such as filling in a wetland for building construction, draining for farmlands or dredging for construction of marinas. Damage is also created indirectly by human induced climate change. 

Worldwide we have lost approximately 50% of all wetlands since the beginning of the 20th century.   Humans have drained, filled and paved over wetlands for development, polluted the waters through increased runoff of pesticides and industrial wastes, removed vegetation and altered the natural flow of water by building dams.  As the climate continues to change, wetlands will continue to be lost and their unique ecosystem altered. 

Wetlands located near cities have especially been impacted by both point and nonpoint sources of runoff.  Pollutants from industrial sites, waste treatment plants, cars and trucks as well as the increased use of fertilizers, pesticides and residential cleaning products have all contributed to overloading of man-made chemicals in wetlands.

The clearing of vegetation both within the wetland and upland alter or destroy the habitat for all species that rely on the wetlands for survival.  In addition to habitat loss, the removal of wetland plants reduces the wetland’s ability to buffer storm surge, flood waters and increases the rate of erosion.   

Humans are altering the natural biogeochemical cycles in wetlands.  Pollution, in the form of runoff from impervious surfaces, agricultural and industrial waste is adding excess nutrients (nitrogen, phosphorous), heavy metals and toxic chemicals into wetlands.   

We are destroying the wetland’s own natural defense system – the plants.  “Tidal marsh plants are amazing ecosystem engineers that can raise themselves upward if they remain healthy, and especially if there is sediment in the water,” said Megonigal of the Smithsonian Environmental Research Center. “We know there are limits to this and worry those limits are changing as people change the environment.” Smithsonian Insider. Science and Nature, December 5 2013. 

Scientists have predicted that the changing climate will cause increases in the earth’s surface temperature, flooding, drought, sea level rise, frequency and strength of storms – all of which will affect the survival of wetlands altering their biological, chemical or physical factors and their ability to provide ecosystem services 

Sea Level Rise

On average, the sea is rising globally at approximately 1/8 of an inch (0.3175 cm) annually.   The actual change in sea level may be more or less than the average depending on the location and geography of an area.  Over time (think along the evolutionary timeframe!)  wetland flora and fauna can adapt to and evolve to survive the changing water levels as hydrophytes trap and accumulate (accrete) sediment, which increases the wetland elevation.   However, with the rapid increase of sea level, many wetlands and inhabitants may not be able to adapt and survive the submergence or drowning of the wetland.  Some of these existing wetlands may be prevented from migrating inland due to hard structures such as development or roads.  Conversely, sea level rise may create more wetlands with increased flooding of upland areas. 

Decrease in Biodiversity

Wetlands are dependent on and sensitive to changes in hydrology as these ecosystems are the middle ground between fully aquatic systems and fully terrestrial systems.  Changes to the amount of water in a wetland through increased or decreased participation or levels of evaporation all can have cascading effects on the species that inhabit them and ultimately cause a loss of biodiversity.  Native flora and fauna  species may be unable to adapt to the rapidly changing environmental conditions and as their populations decline, more aggressive, opportunistic invasive species, will take advantage, invade and overcome the remaining native species.   

As biodiversity decreases so does the ability of a wetland ecosystem to withstand climate change stressors including increasing pressure from storms, pollution, increasing temperatures and sea level rise.  The flora and fauna of a wetland are in a natural balance to ensure all populations stay in the proper proportions for a functioning  ecosystem.  For example, if a certain species of plant beings to grow more rapidly and increase in numbers, it can outcompete other plants for resources such as light and nutrients.  The interactions and relationship between species are as essential as the individual role one species play in the overall function of the wetland. Changes to just one species can topple the entire ecosystem – just like pulling out the wrong block in Jenga® ! 

Superfund Sites

Most wetlands see some amount of runoff from developed areas or agricultural sites but in some cases there is a large amount of dumping (not runoff) of toxic chemicals- these sites that have their own designation and laws pertaining to clean up are called Superfund sites.   Superfund sites are areas polluted with hazardous materials that require a long-term solution.   We have many of these large areas in thUnited states, the Comprehensive Environmental Response, Compensation and Liability Act of 1980 was enacted to mitigate the long-term clean up and restoration of these sites 

According to the EPA’s Toxic Release Inventory, Kotzebue, Alaska is the most toxic superfund site in the United States. In 2018, the Alaskan Red Dog Mine released Lead, Cadmium and Mercury in amounts that   added up to 756 million pounds of toxic material into the environment.   Many of the superfund sites in the US are related to heavy metal toxicity and resulted in an increase in the heavy metal content within wetlands.  Wetlands do not necessarily  need to be close in proximity to the dumping site because groundwater, rainwater and snowmelt transport the heavy metals to the wetlands. 

Looking at a recent map of the United States registered Superfund sites we can see that the majority are located with direct access to wetlands and the others are within the watershed of the toxic site.  


U.S. Superfund Sites

The heavy metals found at sites differ based on the type of mining occurring in the area however, the majority of the heavy metals we see in the United States are:  

  • Lead 
  • Chromium 
  • Arsenic
  • Zinc
  • Cadmium 
  • Copper 
  • Mercury 

Looking at the list above, take into consideration... 

  1. What plants (if any) could be used in a wetland remediation to ‘uptake’ the metal? 
  2. What is the half-life of the metal?  
  3. What is the negative health impact on the people in the surrounding area? 
  4. What is the negative impact that the metal(s) will have on the wildlife in wetlands?  

Hydrophytes help remove toxic chemicals 

Most plants can utilize nutrients including metals that animals cannot necessarily use, some of which are toxic even in low levels to humansSpeaking specifically of metal uptake and storage, known as  phytoremediationwetland plants generally store metals in two ways: below ground in the roots and in their above ground tissue, the  stems and leaves. The concentration of metal in the roots is most beneficial for phytostabilization of the metal.  If the plant is a species that transports the metal to its leaves, the metal can be extruded through the salt glands in the leaves and reappear in the wetland environment.  The accumulation of metals in the leaves and stems can lead to an increase or accumulation of metal in the decomposers and herbivores of the wetlands thus entering the  extensive food web.  This results in marshes and wetlands being a source and sinks for toxic chemicals.   This must be taken into consideration for both management plans for long term cleanup as well as design plans in determining which plants to be  planted.    Although certain plants uptake and remove toxic chemicals, these plants may not necessarily be favored by herbivores in that particular wetland or watershed thereby potentially altering the food web.  Planners and management must take into consideration not only the plants needed to reduce,  remove or transfer the toxic chemicals but also the role of the plant in the entire wetland ecosystem favoring native plants over non-native in order to keep the ecosystem in balance.

Want to learn more about  Biodiversity?  Watch our short video lesson on the impact of human activity on Biodiversity!

Helpful Actions you can take to mitigate climate change

  • If you live near or border a wetland, consider planting a buffer zone of native plants to reduce excess runoff from your property into the wetland. 
  • Reduce or eliminate using fertilizers on your property. 
  • Educate yourself and others on the importance of wetlands and the environmental issues facing wetlands. 
  • Be aware of hitchhikers!   Invasive species are destroying native wetland species by taking over their habitat and food sources.   Don’t release exotic pets into wetland waterways. 
  • Participate on your local zoning committee and stand up to protect wetlands from development. 
  • Reduce your carbon footprint and help slow the rate of climate change.  

Key Vocabulary

Carbon Dioxide
Carbon Emissions
Carbon Sink 
Non-Point Source
Phytostabilization                          Point Sources                                Resilience                                        Superfund Site

Shipping and Navigation

The ocean and humans are inextricably interconnected (Ocean Literacy Principle #6) 

Humans have been taking to the sea since the 1200s when the Phoenicians began using celestial navigation to voyage across the ocean. Since then, we have made tremendous strides in advancing technology for sea-going voyages, navigational tools, harvest of ocean resources and in our understanding of our actions impact on the ocean ecosystems. 

Learning Objectives:

  • Discover how dredging increases the turbidity, releases nutrients and changes the water chemistry.
  • Understand what no net loss implies and compare the functions of a created wetland to a natural wetland.

Balancing Commerce and Conservation

As rivers flow and meet wetlands, the release the sediment and particles that are carried from far upstream. This continual influx of sediment helps to build and stabilize the ecosystem, providing fresh nutrients to the area. Along with the needed nutrients come the “not so wanted” nutrients.  These compounds can come from 1000s of miles away from farms, residential communities or commercial facilities.  In a healthy wetland, the majority of these chemicals can be removed over time by the plants and soil that exist there. 

Dredging a wetland can remove some of the plants that used to balance the influx of nutrients arriving daily. This can also disturb the soil, releasing some of the stored nutrients and gasses that have been there for 100s of years.  With the Army Corp of Engineers at their side, the shipping industry has found a way to achieve their goal of reaching more people and more places while working to preserve the wetlands and land surrounding them.

Channels and Navigation through Wetlands 

The Mississippi River Channel is one of the busiest shipping channels with over 7,000 ships moving in and out of the Mississippi River to the Gulf of Mexico and beyond each year.  The navigation channel needs to be maintained at certain depths and width for the safe passage of ships.  Over time, sediment can accumulate in the channel from upstream making it difficult or impossible for ships to pass through and therefore the channel needs to be continually dredged of excess material.  The amount and frequency of dredging is unique to each river or river system,  that dumps into the delta and depends on factors such as drought, rainfall, snow melt upstreamfarming and agricultural runoff. 

Historically, dredging has not been environmentally friendly to wetland ecosystems as it increases the turbidity of the water.  It also can release nutrients from deep  within  the  sediments disrupting the water chemistry and overloading some of the plants that remove nutrients. In the past, dredging practices removed sediment from the bottom of the shipping channel and either discarded it or dumped it in another part of the wetland.  A new coalition has  recently  formed to use the dredged material to supplement/restore wetlands near the delta where sediment has been lost due to years of water control by oil and gas companies that built extensive networks of canals.  These levees controlled the river flow changing the cycle of flooding and ultimately reducing the amount of sediment replenishing the wetlands. The recycled or reclaimed sediment from dredging projects is being placed along the coast and channel edges restoring lost acreage instead of being dumped at offshore sites.  

Legal Protection of Wetlands

Did you know there is no specific national wetland law in the United States?  In the past management of wetlands has been regulated under various land and water use laws.  It wasn’t until 1977 when President Carter issued a Presidential Executive Order (#11990) that established the first official Protection of Wetlands requiring all government agencies to begin reviewing the use, loss/degradation and preservation of wetlands.   In 1987, the first National Wetlands Policy Forum was held to  investigate the management of wetlands and recommended a “no net loss” goal with a long-term goal of net gain.  The “no net loss” implies that if wetlands are destroyed or lost, there must be an equal acreage of wetlands restored and or created. The focus was on preserving the amount of acreage but not the functions of the wetlands lost.    

Historically wetlands were drained or dredged to allow for coastal development including making way for ships to safely navigate into harbors.  Under the Federal Water Pollution Control Act amendments of 1972 (now known as the Clean Water Act*) it was established that any dredging or filling in of navigable waters required a requested permit from the Army Corps of Engineers (later in 1975 the regulation was updated to include coastal and freshwater wetlands). This permit would ensure that the wetlands and the components of the wetlands are preserved as much as possible. Applying for and obtaining a permit would also regulate the amount of land loss, soil disturbed or fauna misplaced in any one given location, the Army Corp of Engineers could keep a close watch on the frequency of dredging in specific locations. This is a benefit for the wetland but also for the shipping industry as continual dredging and moving of soil can lead to other problems.

*Laws and Policies are continually updated and modified as new information and technologies are developed and federal administrations change.  Most recently the 2015 rule defining “waters of the United States” under the Clean Water Act was repealed and revised.  On June 20, 2020 the Navigable Waters Protection Rule became effective.  This rule narrows the scope of what is under federal jurisdiction, establishing a distinction between federal waters and waters under the control of states and other governmental entities.  It removes interstate and ephemeral streams,  nonadjacent/isolated  wetlands and other features from “waters of the United States.”    The modification to the definition will affect identification/mapping of jurisdictional body of water, permitting processes, conservation/preservation efforts and development projects. 

Key Vocabulary

Carbon Sink
Clean Water Act
Critical Habitat
Navigation Channel
Net loss


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Next Generation Science Standards

MS-ESS-3 Earth and Human Activity. Application of scientific principles for monitoring and minimizing human activity on the environment  

 LS1A-Structure and function of animals as it applies to their habitat  

LS1B- Growth and development of organisms  

LS2A- Interdependent relationships in organisms  

LS2C- Ecosystem Dynamics, Functioning and Resilience  

LS4A- Evidence of common ancestry and diversity  

LS4C- Adaptation  

HS-LS2-2 Ecosystems: Interactions and Dynamics 

HS-LS4-6 Biological Evolution: Unity and Diversity 

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