Life of the Salt Marsh
- Grade Level:
- Fourth Grade-Twelfth Grade
- 1 hour
- Group Size:
- Up to 24 (4-8 breakout groups)
- in the park
OverviewSalt marsh ecosystems are one of the most productive areas in the world. Students learn about producers, consumers, decomposers and the flow of energy and nutrients through hands-on, feet-wet activities. Students will improve their understanding of these critical habitats while sampling fish populations, identifying organisms and measuring abiotic parameters.
Students will be able to:
Understand purpose of biologic and ecologic monitoring and inventories
Recognize factors that force changes in an environment
Hypothesize responses and adaptations of various organisms to changes in their environment
Define Bioindicator Species
Design and create Food Webs
Recognize role of Plankton in aquatic ecosystem
Explain impacts of water quality on organisms
List primary concerns related to climate change
Foster a sense of place and personal connections that leads to stewardship
Understand what a watershed is, what their local watershed is and why it is unique
Appreciate the importance of reliable data collection and the value of data analysis
Enhance understanding that students are impacted by and have an impact on water quality, leading to real world applications and civic responsibility
The global climate is changing. The ocean is warming. A warming ocean affects the volume and the height of the sea due to thermal expansion and the melting of land-based ice. Climate scientists predict that the oceans around the mid-Atlantic coast will rise 1 meter by the year 2100. A rise of 1 meter will have a dramatic effect on our coastlines. A 1 meter increase will flood many of the world's largest cities and result in the loss of two-thirds of the coastal wetlands in the United States
Salt marshes are wetland ecosystems found along an open coastline or within an estuary. The mass of plants and animals (biomass) that is produced naturally on an acre of salt marsh is greater than what is produced on fertilized farmland. Wetlands have a rich food supply that supports many species and add greatly to global biodiversity. Wetlands provide such a safe place for the young animals that they are called the nurseries of the sea. The thick plant growth in wetlands traps sediments, filters out pollutants, and controls flooding. The plants in wetlands that grow above the surface of the water take up carbon dioxide (CO2) from the air and release oxygen.
Organisms need specific conditions to thrive or survive. Scientists predict these conditions will be altered as the climate changes. In a salt marsh, there is a delicate balance between salinity, dissolved oxygen, turbidity and temperature. A change in any of these factors may affect the health and survival of the organisms living in the marshes.
A loss of salt marsh will also cause a loss in local economies. A large number of fish species and shellfish depend on salt marshes for food and shelter during some part of their life. As populations of these commercial fisheries diminish, so will the jobs and industry.To protect our salt marshes and other wetlands, we must recognize their importance, understand how our actions affect these areas and develop ways to minimize the loss and disruption of these critical habitats.
Introduction: Lead students to an area where they can gather on the edge of the marsh.
A healthy salt marsh is smelly, buggy, muddy and home to many creatures. Over 50% of our wetlands and marshes have been filled in and eliminated over the years. Wetlands and marshes were thought of as wastelands — full of disease and pests.
We are now seeing signs of big problems: decrease populations of fish, crabs, shrimp, clams, oysters, scallops; loss of underwater grass beds and poor water quality in bays.
So how does the salt marsh function? How can it be so important? What's out here? Salt water, grass, mud…how do these things work together?
Salt marshes filter run off from land and provide a buffer to shorelines, which is especially beneficial during storms. Salt marshes are the lowest land before submergence and they change as storms and climate changes affect the area. From the dunes to the bay, the march divides into several distinct sections:
· The high marsh has salt meadow hay and some shrubs like groundsel, bayberry and marsh elder.
· Salt pannes are low spots in the marsh, where standing salt water evaporates leaving high salinity soil; they often change and may disappear over time.
· The low marsh has salt marsh cord grass and salt wort.
The grasses and plants on Assateague are well adapted to high salinity and provide habitat for wading birds, crabs and fish. Salt marsh cord grass is also a preferred food of the wild horses that live on Assateague. Introduce salt wort, compare to cactus and how those adaptations allow the plant to grow in this harsh environment. (Encourage students to taste the salt wort.) Examine black needle rush and discuss the habitat it provides for birds and small mammals.
Introduce the decomposers and detritus.
The salt marsh grasses grow all year and then die…the dead grass falls into the mud and then what happens? Hint: decomposers….bacteria break the grass down into smaller and smaller pieces…..its decay or rotting! Bacteria produce rotten egg odors while forming new marsh mud, or detritus. Detritus is the main nutrient ingredient in salt marsh/coastal bay food chain. As tides rise and fall, the detritus gets mixed and transported to the bay. (Encourage students to examine a handful of detritus.)
Activities (hand nets for shrimp, seine nets for fish, plankton nets for microorganisms, abiotic hand tools (aneomometers, thermometers, hydrometers)
Lead students to the crabbing pier or bridge to introduce the consumers and begin hand netting for shrimp.
The shallow, plankton rich coastal bays bordering Assateague Island offer warm water, protected salt marsh habitat, few predators and lots of food which is ideal for young marine creatures. Animal plankton and zooplankton munch on detritus. Plankton and detritus rich water support the filter feeders in the bay like clams, oysters, mussels, shrimp and worms. Filtering benefits water quality and clarity, which in turn, benefit everything in the bay. * At this time students could collect water samples to examine plankton in a lab or when they return to school.
Introduce the relationships between producers, consumers and decomposers.
Submerged Aquatic Vegetation (SAV) beds need sunlight and produce oxygen, provide safe habitats for small or young marine organisms and hold the bay bottom in place, absorbing wave action. Too much plankton or detritus make the water too cloudy and sunlight will not reach the plants. Not enough filter feeders and the water will stay cloudy too. (Encourage students to examine seaweed or eel grass on shore, and any that may be nearby in the water.) * If students are dressed appropriately and weather conditions allow, groups may walk into the bay to examine mussel beds on the shoreline as well as grasses or larger organisms such as comb or moon jellyfish. Seine nets may also be used to gather small fish, shrimp and crabs for hands-on observation.
Conclusion: Engage students in discussion of other factors affecting the salt marsh.
· Climate change will cause the sea level to rise, submerging salt marshes.
· Assateague's wild horses eat the grasses and, compact large areas of marsh.
· Humans activity: bulkheading shorelines, commercial fishing and over harvesting, destruction of SAV, nutrient run off in bays.
Students will take a pre and post assessment test. Student photographs and sketches will be uploaded to park Flickr page and student data will be posted to Hands on the Land webpage.
Assateague Island National Seashore is one of the few remaining intact barrier islands in the Mid-Atlantic coast. Most of the other barrier islands have been heavily developed and their ecological systems and services severly disrupted. The park is a valuable labratory and classroom for students to learn about natural resource managment, protection and stewardship.
Water quality test kits: http://www.lamotte.com/environmental_education_monitoring/product_line/water_monitoring_kits.html
VocabularyBarrier Island- coastal formation that separates open ocean from the mainland by an estuary or lagoon.
Zoo and phytoplankton- passive or week swimming organisms suspended in a water column.
Nekton- actively swimming aquatic organisms able to move independently of water currents.
Watershed- an area of land where surface water from rain and melting snow or ice converges to a single point, usually the exit of the basin, where the waters join another waterbody, such as a river, lake, reservoir, estuary, wetland, sea, or ocean.
Estuary- semi-enclosed coastal bodies of water that have free connection with the open sea and within which sea water mixes with fresh water.
Trophic level- position of species in the food chain.
Autotroph- organism that produces its own food (photosynthesis, chemical synthesis).
Heterotroph- Organism that get energy by consuming other organism.
Abiotic- non-living components in an ecosystem (water, air, rocks, heat, sun).
Biotic- living parts of an ecosystem (bacteria, plants, animals).
Turbidity- Amount of suspended particles in water.
Salinity- total amount of dissolved ions present in sea water.
Inventory and monitoring- Inventory the natural resources to determine their nature and status and monitor park ecosystems to better understand their dynamic nature and condition and to provide reference points for comparisons with other, altered environments.
Bioindicator species- a sensitive species in a region that acts as an early warning to monitoring biologists.
Arthropoda- Phylum of invertebrate animals with jointed legs and segmented bodies (crabs, shrimp, lobsters).
Crustacean- Class within Arthropda phylum with all members being decapods (5 pairs of legs) and a carapace of chitin.