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Marine Conservation Science and Policy Service learning Program

Mangroves are trees that grow in tropical and subtropical intertidal zones. These areas are tough places for plants to grow. During low tides intertidal zones are exposed to air. During high tides they’re covered by salt water. They flood frequently. The soil is poor. But mangrove trees survive and even thrive in these harsh conditions. Big groups of mangroves and other plants that live here are called mangrove swamps, mangrove forests, and sometimes simply mangal.

Module 1: Ocean and Coastal Habitats

Sunshine State Standards SC.912.N.1.1, SC.912.N.1.4, SC.912.E.7.4, SC.912.L.14.3, SC.912.L.14.7, SC.912.L.14.8, SC.912.L.14.10, SC.912.L.15.2, SC.912.L.15.13

Objectives Students will be able to:

Identify and research the types of organisms that live in mangroves.

Name and describe 4 common mangrove species found in South Florida

Compare and contrast the characteristics and adaptations of different mangrove species

Recognize the different life characteristics of mangroves

Identify the different stages of mangroves in the field

Discuss the benefits that mangroves offer to the environment and our community

Measure the growth of mangrove seedlings

Section 3: mangroves

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Vocabulary Estuary- is a partly enclosed coastal body of water with one or more rivers or streams flowing into it, and with a free connection to the open sea.

Halophyte- Any plant that tolerates an environment having a high salt content Mangrove- trees and shrubs that grow in saline coastal habitats in the tropics and subtropics Pneumatophores- aerial roots found on the black mangroves Propagules– the viviparous seeds produced by mangroves

Background

Mangroves are trees and shrubs that grow in saline coastal habitats in the tropics and subtropics – mainly between latitudes 25° N and 25° S. The saline conditions tolerated by various species range from brackish water, through pure seawater (30 to 40 ppt), to water of over twice the salinity of ocean seawater, where the salt becomes concentrated by evaporation (up to 90 ppt).

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There are many species of trees and shrubs adapted to saline conditions. Not all are closely related, and the term "mangrove" may be used for all of them, or more narrowly only for the mangrove family of plants, the Rhizophoraceae, or even more specifically just for mangrove trees of the genus Rhizophora.

Mangroves form a characteristic saline woodland or shrubland habitat, called mangrove swamp, mangrove forest, mangrove or mangal. Mangals are found in depositional coastal environments where fine sediments (often with high organic content) collect in areas protected from high energy wave action. They occur both in estuaries and along open coastlines. Mangroves dominate three quarters of tropical coastlines

Mangroves are found in tropical and sub-tropical tidal areas, and as such have a high degree of salinity. Areas where mangals occur include estuaries and marine shorelines.

Why are mangroves important?

The mangrove community is valued for its protection and stabilization of lowlying coastal lands and its importance in estuarine and coastal fishery food chains. Mangrove forests protect uplands from storm winds, waves, and floods. The amount of protection afforded by mangroves depends upon the width of the forest. Mangroves can help prevent erosion by stabilizing shorelines with their specialized root systems.

The relationship between mangroves and their associated marine life cannot be overemphasized. Mangroves provide protected nursery areas for fishes, crustaceans, and shellfish. Seventy-five percent of the game fish and ninety percent of the commercial species in south Florida are dependent on mangrove ecosystems (Law and Pywell FRC-43). They provide food for a multitude of marine species such as snook, snapper, tarpon, jack, sheepshead, red drum, oysters, and shrimp.

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Many animals find shelter either in the roots or branches of mangroves. Mangroves serve as rookeries, or nesting areas, for beautiful coastal birds such as brown pelicans and roseate spoonbills.

Plants in mangals are diverse but all are able to exploit their habitat (the intertidal zone) by developing physiological adaptations to overcome the problems of anoxia, high salinity and frequent tidal inundation. About 110 species belong to the mangal. Each species has its own solutions to these problems; this may be the primary reason why, on some shorelines, mangrove tree species show

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distinct zonation. Small environmental variations within a mangal may lead to greatly differing methods for coping with the environment. Therefore, the mix of species is partly determined by the tolerances of individual species to physical conditions, like tidal inundation and salinity, but may also be influenced by other factors such as predation of plant seedlings by crabs.

Once established, mangrove roots provide an oyster habitat and slow water flow, thereby enhancing sediment deposition in areas where it is already occurring. The fine, anoxic sediments under mangroves act as sinks for a variety of

heavy (trace) metals which colloidal particles in the sediments scavenged from the water. Mangrove removal disturbs these underlying sediments, often creating problems of trace metal contamination of seawater and biota.

Mangroves protect coastal areas from erosion, storm surge (especially during hurricanes), and tsunamis. The mangrove's massive root system is efficient at dissipating wave energy. Likewise, they slow down tidal water enough that its sediment is deposited as the tide comes in, leaving all except fine particles when the tide ebbs. In this way, mangroves build their own environment. Because of the uniqueness of mangrove ecosystems and the protection against erosion that they provide, they are often the object of conservation programs including national Biodiversity Action Plans.

However, mangroves' protective value is sometimes overstated. Wave energy is typically low in areas where mangroves grow, so their effect on erosion can only be measured over long periods. Their capacity to limit high-energy wave erosion is limited to events like storm surges and tsunamis. Erosion often occurs on the outer sides of bends in river channels that wind through mangroves, while new stands of mangroves are appearing on the inner sides where sediment is accreting.

The unique ecosystem found in the intricate mesh of mangrove roots offers a quiet marine region for young organisms. In areas where roots are permanently submerged, the organisms they host include algae, barnacles, oysters, sponges, and bryozoans, which all require a hard surface for anchoring while they filter feed. Shrimps and mud lobsters use the muddy bottom as their home. Mangrove crabs mulch the mangrove

leaves, adding nutritients to the mangal muds for other bottom feeders. In at least some cases, export of carbon fixed in mangroves is important in coastal food webs.

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Mangrove plantations in Vietnam, Thailand, the Philippines and India host several commercially important species of fish and crustaceans. Despite restoration efforts, developers and others have removed over half of the world's mangroves in recent times.

Survival of the Few Not many plants can make it in the mangal. Only about one hundred plant species are found in most mangrove swamps. Some swamps are home to only one or two species! (The rain forest, on the other hand, has many thousands.) Ferns live in mangrove swamps, as well as some kinds of pine and palm trees.

Please Pass the Salt

Mangroves survive in the very salty mangrove waters because they can get rid of the salt through the glands in their leaves.

The plants that do survive have ―tricks‖ up their sleeves called adaptations to deal with the special challenges. One of the biggest challenges is the salinity, or the amount of salt in the water. The water in a mangrove swamp is so salty it would kill most plants. But the roots of red mangroves contain a waxy substance that helps keep salt out. The salt that does get through this barrier is sent to old leaves that the trees then shed. It’s like taking the trash to the curb so the garbage truck can haul it away.

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Rain, Rain, DON’T Go Away!

Just as mangroves can keep salt out, they have other adaptations to keep freshwater in. They can close up the pores in their leaves. They can also turn their leaves away from the sun to keep from drying out.

All of the plants found only in mangroves are woody and tree-like. They tend to be short with tough, evergreen leaves – another adaptation that keeps the moisture in.

Take a Deep Breath. Well, Try.

Lack of oxygen is a huge challenge in mangrove forests. The soil is covered with salt water every time the tide comes in. Salt water’s low oxygen level means bacteria can thrive. These bacteria free up chemicals and substances harmful to plants, like phosphates, sulfides, and methane.

So mangrove trees grow fancy systems of roots that make the trees look as if they’re growing on a bunch of stilts. The roots ―breathe‖ through knobby holes called lenticels (LEN-tuh-sels). They take in carbon dioxide directly from the air, instead of from the soil like other plants.

Let’s Root for the Roots

The tangle of mangrove roots offers safe habitats for fish, shrimp, and oysters. The roots help stop erosion by anchoring the ground and also lessening the effects of the waves. They prevent silt from damaging reefs and sea grass beds. They trap sediments that can contain dangerous heavy metals, keeping them away from inland waters and fragile animal (and human) populations.

Manatees, Monkeys and a Fishing Cat

Mangrove forests are nesting grounds for hundreds of species of birds. They’re home to manatees, monkeys, turtles, fish, monitor lizards, and, in parts of Asia, the fishing cat. In Florida, mangroves shelter endangered species such as hawksbill turtles, bald eagles, and American crocodiles.

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Biology

Of the recognized 110 mangrove species, only about 54 species in 20 genera from 16 families constitute the "true mangroves", species that occur almost exclusively in mangrove habitats. Demonstrating convergent evolution, many of these species found similar solutions to the tropical conditions of variable salinity, tidal range (inundation), anaerobic soils and intense sunlight. Plant biodiversity is generally low in a given mangal. This is especially true in higher latitudes and in the Americas. The greatest biodiversity occurs in the mangal of New Guinea, Indonesia and Malaysia.

Adaptations to low oxygen

Red mangroves, which can survive in the most inundated areas, prop themselves above the water level with stilt roots and can then absorb air through pores in their bark (lenticels). Black mangroves live on higher ground and make many pneumatophores (specialised root-like structures which stick up out of the soil like straws for breathing) which are also covered in lenticels. These "breathing tubes" typically reach heights of up to thirty centimeters, and in some

species, over three meters. There are four types of pneumatophore—stilt or prop type, snorkel or peg type, knee type, and ribbon or plank type. Knee and ribbon types may be combined with buttress roots at the base of the tree. The roots also contain wide aerenchyma to facilitate oxygen transport within the plant.

Limiting salt intake Red mangroves exclude salt by having significantly impermeable roots which are highly suberised, acting as an ultra-filtration mechanism to exclude sodium salts from the rest of the plant. Analysis of water inside mangroves has shown that 90% to 97% of salt has been excluded at the roots. Salt which does accumulate in the shoot concentrates in old leaves which the plant then sheds. Red mangroves can also store salt in cell vacuoles. White (or grey) mangroves can secrete salts directly; they have

two salt glands at each leaf base (hence their name—they are covered in white salt crystals).

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Limiting water loss

Because of the limited freshwater availability in salty intertidal soils, mangroves limit the amount of water that they lose through their leaves. They can restrict the opening of their stomata (pores on the leaf surfaces, which exchange carbon dioxide gas and water vapour during photosynthesis). They also vary the orientation of their leaves to avoid the harsh midday sun and so reduce evaporation from the leaves. Anthony Calfo, a noted aquarium author, observed anecdotally that a red mangrove in captivity only grows if its leaves are misted with fresh water several times a week, simulating the frequent tropical rainstorms.

Nutrient uptake

The biggest problem that mangroves face is nutrient uptake. Because the soil is perpetually waterlogged, there is little free oxygen. Anaerobic bacteria liberate nitrogen gas, soluble iron, inorganic phosphates, sulfides, and methane, which makes the soil much less nutritious and contributes to mangroves' pungent odor. Prop root systems allow mangroves to absorb gases directly from the atmosphere, and other nutrients such as iron, from the inhospitable soil. Mangroves store gases directly inside the roots, processing them even when the roots are submerged during high tide.

Increasing survival of offspring

In this harsh environment, mangroves have evolved a special mechanism to help their offspring survive. Mangrove seeds are buoyant and therefore suited to water dispersal. Unlike most plants, whose seeds germinate in soil, many mangroves (e.g. Red Mangrove) are viviparous, whose seeds germinate while still attached to the parent tree. Once germinated, the seedling grows either within the fruit

(e.g. Aegialitis, Avicennia and Aegiceras), or out through the fruit (e.g. Rhizophora, Ceriops, Bruguiera and Nypa) to form a propagule (a ready-to-go seedling) which can produce its own food via photosynthesis. The mature propagule then drops into the water which can transport it great distances. Propagules can survive desiccation and

remain dormant for over a year before arriving in a suitable environment. Once a propagule is ready to root, its density changes so that the elongated shape now floats vertically rather than horizontally. In this position, it is more likely to lodge in the mud and root. If it doesn't root, it can alter its density and drift again in search of more favorable conditions.

Geographical regions

Mangroves occur in numerous areas worldwide. See List of mangrove ecoregions.

Africa The mangroves survive the heat of the city of Bombay/ Mumbai and Navi Mumbai

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There are important mangrove swamps in Kenya and Madagascar, with the latter even admixing at the coastal verge with dry deciduous forests.

Nigeria has Africa's largest mangrove concentration, spanning 36,000 km2. Oil spills and leaks have destroyed many in the last fifty years, damaging the local fishing economy and water quality.

Along the coast of the Red Sea both on the Egyptian side and in the Gulf of Aqaba, mangroves composed primarily of Avicennia marina and Rhyzophora mucronata in about 28 stands cover about 525 hectares. Almost all Egyption mangrove stands are now protected.

Americas

Mangroves live in many parts of the tropical and subtropical coastal zones of North, South and Central America.

Continental United States

Because of their sensitivity to sub-freezing temperatures, mangroves in the continental United States are limited to the Florida peninsula and isolated growths of Black Mangrove (Avicennia germinans) along the coast of southern Louisiana and south Texas

Central America & Caribbean

Mangroves occur on the west coast of Costa Rica, on the Pacific and Caribbean coasts of Nicaragua, Belize, Guatemala, Honduras, and Panama and on many Caribbean Islands, such as Curaçao, Bonaire, Antigua, the Bahamas, Saint Kitts and Nevis and St. Lucia. Significant mangals include the Marismas Nacionales-San Blas mangroves in Mexico. Mangroves can also be found in Puerto Rico, Cuba, the Dominican Republic, Haiti, Jamaica, Trinidad, Barbados, and the Pacific coast of El Salvador.

South America

Brazil contains approximately 26,000 km2 of mangals, 15% of the world's total of 172,000 km2.

Ecuador and Peru have significant areas of mangroves mainly in the Gulf of Guayaquil-Tumbes mangroves.

Venezuela's northern Caribbean island, Margarita, possesses mangrove forests in the Parque Nacional la Restinga.

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Colombia possesses large mangrove forests on both its Caribbean and Pacific coasts.

Asia

Indomalaya ecozone

Mangroves occur on Asia's south coast, throughout the Indian subcontinent, in all southeast Asian countries, and on islands in the Indian Ocean, Arabian Sea, Bay of Bengal, South China Sea and the Pacific.

The mangal is particularly prevalent in the deltas of large Asian rivers. The Sundarbans is the largest mangrove forest in the world, located in the Ganges delta in Bangladesh and West Bengal, India.

The Pichavaram Mangrove Forest near Chidambaram, South India, by the Bay of Bengal is the world's second largest mangrove forest. Notably, it has actually increased by 90% in size between 1986 and 2002.

Major mangals live on the Andaman and Nicobar Islands and the Gulf of Kutch in Gujarat.

Other significant mangals include the Bhitarkanika Mangroves and Godavari-Krishna mangroves.

The mangal in the Ganges-Surma-Meghna River System delta was one of the largest in the world.

In Vietnam, mangrove forests grow along the southern coast, including two forests: the Can Gio Mangrove Forest biosphere reserve and the U Minh mangrove forest in the Sea and Coastal Region of Kien Giang, Ca Mau and Bac Lieu province.

The mangrove forests of Kompong Sammaki in Cambodia are of major ecological and cultural importance, as the human population relies heavily on the crabs and fish that live in the roots.

The three most important mangrove forests of Taiwan are: Tamsui River in Taipei, Jhonggang River in Miaoli and the Sihcao Wetlands in Tainan. According to research, there are four existing types of mangrove in Taiwan.[citation needed] Some places have been developed as scenic areas, such as the log raft routes in Sihcao.

In the Indonesian Archipelago, mangroves occur around much of Sumatra, Borneo, Sulawesi and the surrounding islands. While further north they found along the coast of the Malay Peninsula.

Pakistan Pakistani mangroves are located mainly on the Indus delta (the Indus River Delta-Arabian Sea mangroves ecoregion. Major mangrove forests are also found on the coastal line of provinces Sindh and Balochistan.

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In Pakistan, the mangrove forest are located on the coasts of Sindh and Balochistan provinces. In Karachi, land reclamation projects are cutting down mangrove forests and filling then earth and selling them for commercial and urban development.

Middle East

Oman, near Muscat, supports large areas of mangroves, in particular at Shinas, Qurm Park and Mahout Island. In Arabic, mangrove trees are known as qurm, thus the mangrove area in Oman is known as Qurm Park. Mangroves are also present extensively in neighboring Yemen.

Iranian mangrove forests occur between 25°11′N to 27°52′N. These forests exist in the north part of the Persian Gulf and Oman Sea, along three Maritime Provinces in the south of Iran. These provinces respectively from southwest to southeast of Iran, include Bushehr, Hormozgan and Sistan & Balouchestan.

Australia

More than fifty species of Rhizophoraceae grow in Australasia with particularly high biodiversity on the island of New Guinea and northern Australia.

Australia has approximately 11,500 km2 of mangroves primarily on the northern and eastern coasts of the continent, with occurrences as far south as Millers Landing in Wilsons Promontory, Victoria (38°54′S) and Barker Inlet in Adelaide, South Australia.

New Zealand

New Zealand also has mangrove forests extending to around 38°S (similar to Australia's southernmost mangrove incidence): the furthest geographical extent on the west coast is Raglan Harbour (37°48′S); on the east coast, Ohiwa Harbour (near Opotiki) is the

furthest south that mangroves are found (38°00′S).

Pacific islands

Twenty-five species of mangrove are found on various Pacific islands, with extensive mangals on some islands. Mangals on Guam, Palau, Kosrae and Yap have been badly affected by development.

Mangroves are not native to Hawaii, but the Red mangrove, Rhizophora mangle, and Oriental mangrove, Bruguiera sexangula, have been introduced and are now naturalized. Both species are classified as pests by the University of Hawaii Botany Department.

Cultivating Mangroves

Red mangroves are the most common choice, used particularly in marine aquariums in a sump to reduce nitrates and other nutrients

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in the water. Mangroves also appear in home aquariums, and as ornamental plants, such as in Japan.

The Manzanar Mangrove Initiative is an ongoing experiment in Arkiko, Eritrea, part of the Manzanar Project founded by Dr Gordon H. Sato; establishing new mangrove plantations on the coastal mudflats. Initial plantings failed, but observation of the areas where mangroves did survive by themselves led to the conclusion that nutrients in water flow from inland were important to the health of the mangroves. Trials with the Eritrean Ministry of Fisheries followed and a planting system was designed to introducing the nitrogen, phosphorus, and iron missing from seawater. The propagules are planted inside a reused galvanised steel can with the bottom knocked out; a small piece of iron and a pierced plastic bag with fertilizer containing nitrogen and phosphorus are buried with the propagule. As at 2007, after six years of planting, there are 700,000 mangroves growing; providing stock feed for sheep and habitat for oysters, crabs, seashells and fish.

Mangroves for Many Uses

Millions of people in developing parts of the world where mangroves flourish rely on the mangal for a huge portion of their daily needs. They use mangrove wood for fuel and to build boats and furniture. They use the bark for dye and medicine. They use leaves for tea and animal feed and the fruit for food. These coastal swamps protect property and lives during storms and hurricanes by acting as a buffer against the winds and waves.

Harshest Threat: Humans

Mangrove trees survive harsh natural conditions, but threats from pollution and industry are an even bigger problem. The land where mangroves live has often been sold cheaply to businesses, which cut down many of the trees. Sewage, weed-killers, and spilled oil are extremely unhealthy for the mangroves.

As human activity around mangroves increases, more and more mangrove forestland is lost. Dredging coastal areas and filling them in to make them suitable for building also leads to destruction of mangroves. Artificial dikes cause long-term flooding that the mangroves simply cannot handle. Thousands of acres have been cut down to make room for the artificial ponds required by the shrimp industry.

Even the beauty of mangrove swamps threatens them. More tourists are coming to see them, and with more tourism comes more garbage, along with air and water pollution.

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A Global Rescue Mission

Mangroves do not recover quickly from severe damage. This mangrove forest in Honduras never recovered from the destruction caused by the development of a shrimp farm.

According to some experts, half of the world’s mangrove swamps have already been lost. So is all hope lost? Not at all. Environmental activists are raising awareness of mangrove swamps’ unique features and benefits around the world. They are trying to pass laws to protect mangroves, and to encourage people to stop buying shrimp grown in areas where mangroves once used to thrive.

The Mangrove Replenishment Initiative (MRI) could make a difference around the world. One of MRI’s goals is to research and develop effective ways of replanting mangrove forests. Growing these trees from seeds, from the ground up, is difficult. It’s not enough to drop seeds and hope for the best.

The Forestry and Agriculture Organization of the United Nations is also involved in studying ways to preserve mangroves. In Belize, where increased population and the construction of homes threatened mangrove swamps, an educational workshop helped to raise the residents’ awareness of the true value of the mangroves. A similar program

might be introduced in Malaysia.

In Florida, the Mangrove Trimming and Preservation Act makes it illegal to use poisonous chemicals in mangroves. People need a permit from the government before they can disturb mangroves in any way.

What Can You Do?

How can you do your part to save the mangroves and the rich variety of life that depends on them?

Find out more at your local library, or go online. Get people interested in mangroves. (Weird trees, endangered animals, native

populations in trouble—shouldn’t be too hard!) Don’t buy shrimp raised on former mangrove land. Be an all-around friend to the

environment. Donate money to the Mangrove Action Projects.

Exploitation and conservation

The United Nations Environment Program estimated that shrimp farming causes a quarter of the destruction of mangrove forests.

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Grassroots efforts to save mangroves from development are becoming more popular as the benefits of mangroves become more widely known. In the Bahamas, for example, active efforts to save mangroves are occurring on the islands of Bimini and Great Guana Cay. In Trinidad and Tobago as well, efforts are underway to protect a mangrove threatened by the construction of a steelmill and a port. In Thailand, community management has been effective in restoring damaged mangroves.

Approximately 35% of mangrove area was lost during the last several decades of the twentieth century (in countries for which sufficient data exist, which encompass about half of the area of mangroves).

It has been cited that Mangroves can help buffer against Tsunami, cyclones, and other storms. One village in Tamil Nadu was protected from Tsunami destruction - the villagers in Naluvedapathy planted 80,244 saplings in order to get into the Guinness Book of World Records. This created a kilometre wide belt of trees of various varieties. When the Tsunami struck, much of the land around the village was flooded, but the village itself suffered minimal damage.

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Mangrove Removal Regulation

Mangrove trees along natural and many artificial water bodies are protected from removal. Mangrove trees are protected from removal by Dock and Shoreline regulations, the natural waterway buffer requirement and the Tree Protection Code. In many cases, mangrove trees can not be removed without first obtaining a vegetation removal permit from Lee County. Mangroves are typically located in wetlands. Impacts or removal of mangrove wetlands may require permits from state and federal agencies

Mangrove Pruning Regulation

Since July 1, 1996, Lee County has generally not been involved in the regulation of mangrove tree pruning. Below are state agencies that permit mangrove pruning per the

Mangrove Trimming and Preservation Act (Florida Statutes Sections 403.9321-403.9333) - www.leg.state.fl.us/Statutes/

FLORIDA DEPARTMENT OF ENVIRONMENTAL PROTECTION - (DEP)

South Florida District Office 2295 Victoria Avenue, Suite 364 Fort Myers, FL 33901 Telephone (239) 332-6975 Fax (239) 332-6969 http://www.dep.state.fl.us/

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Florida Mangroves

Red mangrove (Rhizophora mangle) The red mangrove is one of the four mangrove species found in the mangrove ecological community. The other species within this community are the white mangrove (Laguncularia racemosa), black mangrove (Avicennia germinans), and buttonwood (Conocarpus erectus). Scientifically, they are distantly related and are only grouped based on ecological function within the community.

The mangrove community plays an important role in tropical and subtropical regions of the world. Different mangrove species protect and stabilize low lying coastal lands and provide protection and food sources for estuarine and coastal fishery food

chains. Mangro

ves serve

as feeding, breeding, and nursery grounds for a variety of fish, shellfish, birds, and other wildlife. Mangroves also produce 3.6 tons per acre of leaf litter per year which benefit estuarine food chains. An estimated 75% of the game fish and 90% of the commercial species in south Florida depend on the mangrove system.Their tall arching roots called prop roots easily identify the red mangroves. Prop roots supply air to the

underlying roots and provide support and stability to the red mangrove. They also trap mud and silt that flows with the tide, thus gradually increasing the soil around them. They

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are found closer to the water than the other mangroves in the community due to their high salt tolerance. The wood is used for fuel, piling, crossties, and charcoal. The red mangrove is also known for its large quantity of tannins found in the bark. Red mangroves range from Daytona Beach and Cedar Key southward.

Waterfront development has strongly affected the habitat of mangrove communities. Removal of these trees and the destruction of mangrove wetland habitats endanger the natural systems of Florida's coastal zone. The result of removal or damage to the mangrove communities has affected Florida's coastal land by causing erosion and a decrease in food at the base of the food chain supporting commercial fisheries.

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Identifying Characteristics

Size/Form: The red mangrove is a tall tree that reaches 70' to 80' in height in the tropics; however in Florida, it is characterized as a short bushy tree reaching about 20' in height. It is characterized by its numerous above ground roots called prop roots.

Leaves: The persistent leaves are oppositely arranged, 3" to 5" long and 1" to 2" wide. They are elliptical in shape, dark green on top, and paler below. Leaf margins are smooth.

Flowers: The flowers on the red mangrove are a pale yellow and appear in the spring.

Fruit: The leathery fruit is a rusty-brown conical berry. Before it falls from the tree, one seeds germinate and send down an initial root, 6" to 12" long. When the fruit falls this root lodges in the soil and the top begins to grow immediately. This is a unique plant adaptation to the wet environment.

Bark: The thick gray to gray-brown bark is ridged and scaly.

Habitat: The red mangrove grows in brackish areas along creeks, bays, and lagoons.

Black mangrove (Avicennia germinans) Black mangrove is a communal species that plays a key role in the mangrove ecosystem. It contributes to the ecological community by trapping in the root system debris and detritus brought in by tides. The community is valued for its protection and stabilization of low-lying coastal lands and its importance in estuarine and coastal fishery food chains. Black, white, and red mangroves serve as feeding, breeding, and nursery grounds for a great variety of fish, shellfish, birds, and other wildlife. Black mangrove grows in coastal tidal areas throughout the tropics and subtropics of America and Africa. It grows closer inland from the shore. There it can be reached only by high tides. It is found on the gulf coast of Florida from Cedar Key to Key West and back up to St. Augustine on the Atlantic side. Southwest Florida islands contain the most concentrated area of mangroves. The tree becomes

shrubby toward the north of its range due to the cooler weather. Freezing temperatures prevent the range from extending northward.

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The wood is dark-brown to nearly black. It is preferred for its strong, heavy, and hard qualities. Black mangrove wood has been used as posts, fuel, and for marine construction. Black mangrove contains tannin in the bark and has been used to prepare leather products.

Black mangroves bloom in June and July with white flowers. When in bloom, black mangrove nectar is used for "mangrove honey" production. This honey is of very high quality. Considerable quantities were made in the United States until about 1895. Hurricane destruction of the best forests decreased honey production. In recent years, there has been renewed interest in this product.

Black mangroves can be easily identified by the numerous pencil-like breathing tubes, called pneumatophores, which grow vertically from the mud to just above the highest sustained water level. Like the prop roots of the red mangrove (Rhizophora mangle), these provide air to the underground and underwater roots. Unfortunately, the diverse natural community provided by the mangrove forest is declining due to the invasion of overpowering plant species, such as the Brazilian pepper, and urban development.

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Identifying Characteristics

Size/Form: Black mangrove is a small to medium-sized tree that reaches heights of 50'. It is small and shrub-like toward the north end of its range.

Leaves: The leaves are simple, oppositely arranged, persistent, and 2" to 4" long by ¾" to 1 ½" wide. The oblong shaped leaves usually have shiny upper surfaces coated with salt crystals while the underneath surface is hairy. The leaf base is wedged and the leaf tip is rounded. The leaf margin is smooth and sometimes slightly rolled down along the side edges.

Fruit: The egg-shaped capsule is green and 1 ½" long by 1" wide, has splits along two edges, and contains one seed.

Bark: The dark-brown bark has long, vertical furrows between flat, scaly, squarish blocks. The bark sloughs off to reveal an orange-red inner bark.

Habitat: Black mangrove grows in the wet soils of coastal high-tide shores of Florida in the mangrove ecosystem.

White mangrove (Laguncularia racemosa)The white mangrove is one

of four mangrove species in the mangrove community. The other species are the red mangrove (Rhizophoria mangle), black mangrove (Avicennia germinans), and buttonwood (Conocarpus erectus). Scientifically, they are distantly related and are only grouped based on ecological function within the community. White mangroves range from Volusia County and Levy County southward. The mangrove community plays an important role in the tropical and subtropical regions

of the world. Different mangrove species protect and stabilize low lying coastal lands and provide protection and food sources for estuarine and coastal fishery food chains.

Mangroves serve as feeding, breeding, and nursery grounds for a variety of fish, shellfish, birds, and other wildlife. Mangroves also produce 3.6 tons per acre of leaf litter per year, which benefit estuarine food chains. An estimated 75% of the game fish and 90% of the commercial species in south Florida depend on the mangrove system.

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The white mangrove is easily differentiated from other mangrove species by its leaves and root system. The leaves are rounded at the base and the tip and are smooth underneath. Each leaf has two glands, called nectarines, at its base that excrete sugar. Many insects feed on the excreted sugar. Depending on habitat conditions, the white mangrove may possess pneumataphores and/or proproots. Pneumatophores are cone-shaped extensions of the root system protruding from the ground. Pneumatophores are thought to function as the trees' means of obtaining oxygen for the roots during flooded conditions. Prop roots are tall arching roots originating from trunks and branches. The white mangrove is fast growing in fertile habitats.

A common belief that the mangroves build land is usually not true. However, after they colonize newly formed sandbars and embankments, their roots may entrap and accumulate soil, helping to stabilize soil during rough weather.

Identifying Characteristics

Size/Form: The white mangrove is a small low sprawling shrub or tree that reaches 40' to 60' in height. It is characterized by its narrow rounded crown.

Leaves: The persistent leaves are oppositely arranged and are 1" to 3" long. The leaves are leathery and possess small glands on the bottom of the leaf towards the outer edges.

Fruit: The leathery fruit is a reddish-brown drupe that contains a dark red seed.

Bark: The 1" thick reddish-brown bark is ridged and scaly.

Habitat: White mangrove grows in areas where tides may be high and also in lagoons.

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Buttonwood (Conocarpus erectus)Buttonwood is a shrubby

mangrove tree that has a picturesque appearance when exposed to constant seashore winds creating an attractive addition to the beach landscape. Its name refers to the red-brown, cone-like fruits. Buttonwood is usually low branching and multi-trunked. It is native to Florida's mangrove forest ecosystem.

As a tropical tree, buttonwood does not grow north of Florida's Cape Canaveral and Cedar Key. From this northern limit, buttonwood growth in the brackish tidal lagoons and bays ranges to the Florida Keys and Bermuda, the West Indies, Central and South America, and western Africa. Buttonwood is highly tolerant of full sun, sandy soils, salty conditions, and the soils of shaded and moist oak hammocks. They are found on the edges of salt flats, rocklands of the Florida Keys, borders of fresh and brackish marshes, edges of hammocks, sometimes on spoil and other disturbed areas in South Florida.

Buttonwood is often used for seaside landscaping. The wood was used for firewood, cabinets, and making charcoal. It is very strong wood and ideal for smoking meats and fish because it burns slowly and releases generous quantities of heat. Buttonwood is tough and long lasting in the landscape. It can withstand the rigors of urban settings and makes a durable street or parking lot tree.

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Identifying Characteristics

Size/Form: Buttonwood is a small tree that seldom reaches heights of 40'. It is usually small and shrub-like.

Leaves: The leaves are simple, alternately arranged, persistent, and are 1" to 4" long by ½" to 1 ½" wide. The oblong shaped leaves usually have dark, shiny green upper surfaces while the underneath surface is paler and smooth with silky hairs. The leaf base is wedged with a pair of marginal glands. The leaf tip is tapering and the margin is smooth.

Fruit: The fruit is a tiny reddish, leathery drupe. The scale-like drupes are borne in heads that resemble a cone that is 1" in diameter.

Bark: The dark-brown to black bark has irregular fissures that form flat, interlacing, scaly ridges.

Habitat: Buttonwood grows in the silty, muddy shorelines of tidal bays and lagoons, commonly landward of the fringe of mangrove community and above high tides. They are also found on the edges of hammocks, salt flats, marshes, and sandy rocklands.

Florida Mangroves Zonation

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Activity: The Coast Protectors

Duration: 1 hour

Objectives

Students construct models to demonstrate how mangroves help protect shorelines and contribute to the growth of the Florida peninsula.

Materials Photos of different mangrove habitats and species

3 copies of the Mangrove Concentration worksheet

3 sheets cardstock

Glue

2 large, shallow trays (4‖x12‖x18‖ – a baking or roasting pan)

10 Sheets of Styrofoam (about ½ inch thick)

Sand (enough to cover the bottoms of the trays 1-3 inches)

1 package red pipe cleaners

1 package black pipe cleaners

1 package white pipe cleaners

1 package green pipe cleaners

2 strips of Styrofoam or plastic, cut to fit into the tray and at least as deep (4‖x12‖)

Additional small pieces like leggos or jewelry boxes to represent homes, buildings, etc.

Procedure 1. Before class begins, make the Mangrove Concentration cards

Glue or copy the ―front‖ (adaptation descriptions) to a sheet of cardstock and cut out cards

Cut out the ―back‖ (mangrove species) and paste to the back of the front cards as follows:

o 1, 5, 9, 13 – red mangrove o 2, 6, 10, 14 – black o 3, 7, 11, 15 – white o 4, 8, 12, 16 – buttonwood

Repeat to make 2 more sets of cards

Lay the cards on the desk for 3 groups, with the ―front‖ face up (the side with the adaptations

2. Show students the mangrove photographs. Discuss the types of mangroves common in Florida and the characteristics of each species.

What are the 4 species of mangrove in South Florida?

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o White, black, red, and buttonwood. o The buttonwood is not a ―true‖ mangrove

How are these species alike or different? o Each mangrove species have their own adaptations that help them

to survive in the saline environment. o Also, the mangroves exhibit zonation, such that they are found in

different areas on the coast (the reds are in the water and the buttonwoods are more upland, away from the water).

3. Divide the class into 3 groups. Tell the students that they will play Mangrove Concentration.

Set each group in front of one set of cards.

Tell students that they must take turns flipping two cards at a time. If the cards match, they player keeps the cards. If they don’t match, both cards must be flipped back over.

When all the cards have been matched, have students present the mangrove characteristics/adaptations described on the cards for each species.

4. Discuss the similarities and differences among the types of mangroves. 5. Inform students that they are going to construct 2 models to demonstrate the

roles mangroves play in the coastal community.

One model will include simulated mangroves and the other will not.

Encourage students to contribute ideas for building the models. 6. In the bottom of BOTH trays construct shoreline topography out of the Styrofoam

One end represents the coastline; the other end, inland.

Add enough washed coarse sand to cover the shoreline topography to a depth of 1-3 inches.

7. Randomly place several small boxes of leggo pieces inland to represent condos, homes, hotels, etc.

8. On one model, use the colored pipe cleaners to simulate the 3 types of mangroves and buttonwood.

When adding mangroves to the model, make sure they are securely inserted into the Styrofoam. The ―black mangroves‖ may have to be glued or taped before adding sand.

o Have students assist in making the pipe cleaner mangroves as many will be necessary

For red mangroves: o Twist several red pipe cleaners together at their midpoint to form

the trunk o Spread the ends of individual pipe cleaners apart to form prop

roots. o Add a coastal fringe of red mangroves to the model (from one side

to the other) by interlocking the simulated prop roots and pressing them into the sand along the shoreline of the model

For the black mangroves:

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o Using the black pipe cleaners, use the same technique as for the red, but spread the simulated roots apart and flatten them like the spokes of a wheel.

o Add pneumatophores by twisting short pieces of pipe cleaner around the flattened roots so that they project upwards.

o Place the black mangroves in a band behind the red mangroves by pressing the roots into the sand so the pneumatophores project above the surface.

o Black mangroves may have to be made and added to the model first before adding the sand.

For white mangroves (white pipe cleaners) and buttonwoods (green pipe cleaners):

o Push the twisted end of a bunch of pipe cleaners into the sand. o Add a band of white mangroves behind the black mangroves o Add a band of buttonwoods behind the whites

The entire coastal fringe of simulated trees should be about 4-6 inches across.

To simulate branches on all the trees, simply spread apart and arrange the tops of the twisted pipe cleaners.

9. Add water to the shoreline end of both models, to about 1/3 the depth of the tray.

For the mangrove model, be sure the water barely covers the lower part of the prop roots of the red mangroves and covers all of the roots of the black mangroves, so that only the pneumatophores project above the water.

10. Place a small piece of Styrofoam or plastic in the water end of each tray.

Move it back and forth to simulate waves

Push it strongly toward the beach to simulate storm surge 11. Have students observe, record, and discuss the effects.

What were the differences between the two models?

When waves and the storm surge were simulated, what did you observe?

What effect did the mangroves have in the model?

What implications does this have for our coastlines?

What do you think would happen if we lost all our mangroves?

Activity adapted from Discover a Watershed.

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Mangrove Concentration Cards (Front)

1 Largest leaf

2 With silvery underside of leaf

3 Glands on petiole

4 Salt excreted through leaf

5 Prop roots

6 Pneumatophores

7 Smallest true mangrove

8 Rough bark in older trees

9 Salt excluder

10 Salt excretion

11 Salt extruder

12 Grows in higher less saline habitat

13 Cigar-like propagules

14 Lima bean-shaped propagule

15 Triangular propagule

16 Button-shaped seed

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Mangrove Concentration Cards (back)

Red Mangrove

Black Mangrove

White Mangrove

Buttonwood

Red Mangrove

Black Mangrove

White Mangrove

Buttonwood

Red Mangrove

Black Mangrove

White Mangrove

Buttonwood

Red Mangrove

Black Mangrove

White Mangrove

Buttonwood

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Activity: Mangrove Field Study Duration: 1.5 hours

Objectives

Journey outside the classroom to a mangrove forest where students can investigate some special mangrove characteristics.

Materials 5 tape measures

5 transects

5 Clipboards

Pencils

5 thermometers

Refractometer

Anemometer

5 Clinometers

Mangrove PowerPoint

Mangrove Life Cycles Data Sheet

Procedure 1. The week prior to conducting the activity, select a suitable mangrove site.

This location should have 3-4 of the common mangrove species, and demonstrate the community succession that is often found in mangrove habitats.

Also, be sure to check the tides and arrange to visit the site during low tide, if possible.

2. Introduce students to mangroves. Lead a class discussion using the following guiding questions:

What makes mangroves different from other trees?

What are some of the adaptations that allow mangroves to survive in salt water?

Explain why certain mangrove species are found closer to or further from the shore.

What are some of the benefits provided by mangroves?

Why are mangroves a great habitat?

Describe some reasons why it is important to protect mangroves. 3. Introduce the term ―propagules‖ to the students and discuss the mangroves’

reproductive strategy

Mangrove trees develop seeds known as propagules that sprout while on the tree. They are long and pencil shaped. When the propagules ripen,

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they fall off the tree and either land in the soft mud below or into the water where it is carried away.

Propagules are buoyant, and thus able to float vertically in the water. They can travel from several days to months in the water until it finds a shallow area to settle.

Once a propagule is planted, it begins to develop prop roots, which help to stabilize the tree in the water. As the mangrove grows, the prop roots allow for sand, detritus and other sediments to collect, which makes the location more suitable for settlement for other wandering propagules. Eventually a mangrove forest (if next to the shore) or a mangrove island (if offshore) forms.

4. Explain to the students that today they will have the opportunity to participate in a Mangrove Field Study where they will observe and measure some of these special mangrove characteristics.

5. Divide students into 5 teams. Give each team a tape measure, thermometer, clipboard, clinometers, transect, and data sheet.

6. Tell students that each team will conduct its own field study. As a part of the field study, groups will:

Choose an area that shows mangrove succession

Record the mangrove species observed

Run a transect line to measure the length of the area and identify the distance of each species from the water

Record the temperature, salinity, and wind speed

Record the average height of each species’ canopy

Locate and measure the growth of a seedling

Describe the organisms observed in their mangrove area. 7. Take the students to the designated areas.

Demonstrate how to use the clinometer and how to measure the seedlings.

Direct each group to: o Locate an area o Complete their measurements and record their data.

Each member in the group must participate. 8. After returning to the classroom, allow each group about 10 minutes to review

their results. 9. Allow each group to present their conclusions on whether they think the area

they surveyed is a healthy habitat. Students should consider the following questions:

What are some indicators of a healthy mangrove ecosystem?

What are some ways that a damaged mangrove area can be restored?

How would you bring awareness about this fragile ecosystem to the public?

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Mangrove Data Sheet

Group Members ______________________________________________

Date________________________________________________________

Field Work

A. Site Selection – select an area that has multiple species of mangroves, and if possible, shows zonation. Area should also have several seedlings present.

Be sure it is an open space where your group can conduct the field work safely.

Avoid areas that are too muddy.

B. Site Description

Write a brief, general description of your site. Where is it located? Is the area diverse (what other plants or organisms can you see besides mangroves)? Is it high or low tide? Sunny or shaded? Describe anything that you see. ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

C. Plants

Conduct a survey of the plants in your site area, including the mangroves and any other plant species that might be a part of your site.

When measuring height, take measurements from 5 trees and calculate the mean

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Species Name

Tree Height Descriptive Features

1 2 3 4 5 Mean Leaf Trunk Root

Ma

ng

rove

s

Oth

er

Pla

nt

Sp

ec

ies

D. Site Profile

Use the transect to measure the entire length of your site from the mangroves furthest in the water (your origin) to the last mangrove in shore. Length of site area: _________

Measure the length of each mangrove zone starting with those closest to the water. Species 1: ______________________ Species2: ______________________ Dist. from origin: ____ Zone length: ____ Dist. from origin:____ Zone length: ____ Species 3: ______________________ Species4: ______________________ Dist. from origin: ____ Zone length: ____ Dist. from origin:____ Zone length: ____

Sketch the study area and its vicinity. Make sure to include the relative measurements of the zones in your drawing, as well as symbols to represent each species present.

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Comments__________________________________________________________________________________________________________________________________________________________________________________________________

F. Physical Factors

Measure temperature, salinity, and wind speed

Take each measurement 5 times, and then calculate the mean values.

Air Temperature

Water Temperature

Soil Temperature

Salinity Wind Speed

1

2

3

4

5

Mean

Symbols Key

Water

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E. Organisms

Conduct a survey of the animals and different organisms you observe in your site area

Species Name

Location Found

External Features Behavior

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

For location, describe where you find the organisms, e.g. above leaf, below leaf, on trunk, on mud surface, in leaf litter, in water, in crevice, etc…

F. Seedling Growth

Locate mangrove seedlings in your site area (see picture).

Starting from the substratum, measure the height of the hypocotyls or zero node, followed by successively higher nodes along the main stem until reaching the base of the apical node. This is measured as the last in the present sequence.

Count the heights of all the nodes along the main stem from the substratum to the apical node.

Calculate intermodal extension by estimating the difference between the height of the node above, minus the one below.

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Plot the data in a graph with node number (x-axis) vs. intermodal extension (y-axis)

Repeat with 5 more seedlings.

If your seedlings have more than 6 nodes, extend the chart on the back.

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Se

ed

lin

g

Height – substratum to zero node

Node Count

Node 1 Node 2 Node 3 Node 4 Node 5 Node 6

He

igh

t

Inte

r-no

da

l

He

igh

t

Inte

r-no

da

l

He

igh

t

In

ter-n

od

al

He

igh

t

Inte

r-no

da

l

H

eig

ht

Inte

r-no

da

l

He

igh

t

Inte

r-no

da

l

1

2

3

4

5

Inte

rno

da

l E

xte

nsio

n

Node Number

Key to

Seedlings

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Resources http://www.globio.org/glossopedia/article.aspx?art_id=39 http://www3.leegov.com/DCD/Environmental/Mangroves.htm http://en.wikipedia.org/wiki/Mangrove http://water.epa.gov/type/wetlands/mangrove.cfm http://www.ncl.ac.uk/tcmweb/tcm/mglinks.htm http://www.wettropics.gov.au/pa/pa_mangroves.html http://www.floridaplants.com/horticulture/mangrove.htm All images are taken from Google Images.