Coastal Erosion

What is beach erosion?

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Beach Erosion” by versageek licensed under CC by 2.0

Beach erosion occurs when waves and currents remove sand from the beach. The loss of sand causes the beaches to become narrow and lower in elevation. Storm waves carry the sand offshore, depositing and storing the sediment in large sand bars.

Dune Erosion

16011876170_c590dec35b_o.jpgWindy” by Susanne Nilsson licensed under CC by 2.0

Dune erosion occurs when a storm surge creates waves higher than the beach. This allows them to attack and erode the coastal dunes. When sand is removed from the dune the front of the dune becomes steep. The volume and elevation of the dune is reduced due to the erosion process. In return this makes the dune more vulnerable to future storms and the potential for over wash. Then the eroded sediment is carried off shore and stored in large sandbars. The sand dune can recover over a period of years, gaining in elevation and volume via wind-blown sand.

Over wash

Over washing is when storm induced waves exceed the height of the sand dunes, sand is transported over the top of the dune and deposited inland. Over washing can cause a significant change in the landscape of the island.  During this process dunes are often completely eroded away and the sand is deposited inland in large layers called over wash fans. These fans can bury the first floors of homes, cover roads, fill ponds, and cover vegetation. In some cases these fans, depending on the severity of the storms can cover the entire width of the island. When the sand is transported from seaward to the landward side of the island, the island migrates landward in a process known as barrier island rollover.

Marsh Erosion

Marsh erosion occurs along wetlands that are exposed to the open ocean and wide bays. Waves induced by storms and currents erode the muddy wetlands soil, causing the fragile coastlines to erode significantly, often it transforms a land area into open water. One recent example of marsh erosion is the loss of over hundreds of square miles of land during hurricanes Katrina and Rita in 2005 (Barras and Johnson, 2006). want to learn more about this? Click here!

 

When does this become an issue?

Coastal erosion becomes a problem when there is no room to accommodate the changes that are occurring. Highly urbanized coastal zones will certainly face difficulties with coastal erosion. European coasts for example, are facing increasing urbanization. The demand for the shoreline defenses and erosion control also increases. This could lead to self reinforcing effect as additional property and economic activities require further and often more robust defenses. These developments will all lead to reduced coastal resilience since the coastline has nowhere to move. It is a questionable if this type of development is sustainable in the long term, especially with climate change.

 

Climate change and coastal erosion

Climate change will lead to an increase in coastal erosion. The rising sea level is the most important contributor. A rising sea level implies an increase in sediment demand, which results in coastal retreat. Higher sea levels will rise the water level, this allows waves to break closer to the shore line and transmit more wave energy to the shoreline. This will promote erosion and coastal retreat at locations that lack sediment. There are other drivers to this issue these include increased storms, higher waves, and change in wind direction. The conditions and performances of existing coastal defenses structures may also deteriorate through interactions with rising sea levels, higher waves, and more storms.

If you wan to learn more about sea levels rising, check out Marisa’s blog!

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“Sea-level-rise scheme” by Wikimedia Commons licensed under CC by 3.0

What can help with erosion?

There are a few different ways that we may be able to manage coastal erosion….

Port-a-bag barrier walls these bags are self-erecting and are an excellent way to create a stable barrier for coastal restoration. They are a sustainable leave in place, or as a temporary solution. They can protect dunes, rebuilding coastal shorelines or preserving beaches. They proved a solid defense against incoming tides and wave action.  Breakwater tubes are more commonly used for long, demanding, or extended shoreline support. This tubes acts as a first layer of defense against waves as the break along the shore. This allows the beach to naturally retain sand and helps limits the deterioration of the shoreline. The coconut fiber log is also another mechanism to use. There are natural fiber logs that are designed to help with erosion control along the beaches. Logs can be put in sand dunes or vegetative areas that help establish roots. Geotextiles are also a product that can be sued. They are paired with retaining walls to increase stabilization and strength.  Erosion control mats are sometimes used as an option as well. They are mats that are typically designed to further the growth of vegetation by stabilizing an area long enough for plants, trees, and roots to establish them.

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Seagrass

What is a seagrass?

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Seagrass Halodule uninervis” by Wikimedia Commons licensed by CC by 2.0

Many of us make think a seagrass is seaweed, but it is not. Seagrasses belong to a group of plants called monocotyledons. This group contains plants like grasses, lilies, and palms. Seagrasses have leaves, roots, veins, produce seeds and flowers just like a regular flowering plant like you see on land. Chloroplasts are in the tissues of sea grasses and use the suns energy to convert carbon dioxide and water into sugar and oxygen for growth via photosynthesis.  The veins of seagrasses carry nutrients and water throughout the plant. These plants have pockets called lacunae that keep the leaves buoyant and exchange oxygen and carbon dioxide throughout the plant. Seagrasses lack a stomata. Stomata is the tiny the pores that open and close to control water and gas exchange. Instead seagrass has a cuticle layer which allows grasses and nutrients to diffuse directly into and out of the leaves from sediment.

Where are they found?

Seagrasses can be found in salty and semi salty waters around the world. Seagrasses depend on light for photosynthesis so they are typically found in shallow waters so the plant can get the nutrients and the sunlight they need for survival.

Biodiversity

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Green Sea Turtle grazing seagrass” by Wikimedia Commons licensed by CC by 3.0

There are 72 species of seagrasses!  They are dived into four main groups: Zosteraceae, Hydrocharitaceae, Posidoniaceae and Cymodoceaceae. More commonly known as eelgrass, turtle grass, tape grass, shoal grass, and spoon grass. Seagrasses range from species that have long flat blades that look ribbons or to fern and paddle shaped leaves. They also can range in cylindrical or spaghetti blades, or branching shoots. Zostera caulescens is the tallest seagrass species; it is found growing up to 35 feet in japan.

 

Why are they important?

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Syringodium filiforme (manatee grass) (southeastern Graham’s Harbour, San Salvador Island, Bahamas) 1” by James St. John licensed by CC by 2.0

When areas of the ocean are free of seagrasses, they are vulnerable to intense wave action from currents and storms. Their roots grow both horizontally and vertically, this helps stabilize the sea bottom in a way similar to the way land gasses prevent soil erosion. Seagrasses also provide food, shelter, and nursery grounds to fish. Manatee’s and sea turtles directly eat the grass; others use the seagrasses to directly to provide nutrients. Detritus from bacterial decomposing of dead seagrasses plants provide foods for worms, sea cucumbers, crabs, and filter feeders like anemones and ascidians.  Seagrasses also provide an ideal location for juvenile and small fish to escape from larger predators. Some species use sea grasses is a buffer from currents. Some of these species are starfish, clams, worms, sea cucumbers, and sea urchins. Sea grasses also help with the water quality. They trap sediments and particles suspended in the water column, which helps increase water clarity

 

Mangroves

What is a mangrove?

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Mangroves” by Pat (Cletch) Williams licensed by CC by 2.0

Mangroves are a group of trees and shrubs that live in the coastal intertidal zone. Many mangrove forests can be recognized by their dense tangle of prop roots that make the trees appear to be standing above the water. This tangle of the roots allows for the trees to handle the daily rise and fall of tides. This means that these forests get flooded twice a day. The roots for the trees allow for the movement of slow tidal water causing the sediments to settle out of the water. Mangroves stabilize the coastlines, reducing erosion from storms, currents, waves and tides. The intense system of roots is attractive to fish and other organisms seeking food and shelter from predators. You can only find mangrove forests at tropical and subtropical latitudes near the equator because they cannot withstand freezing temperatures.

 

How do they survive in the salt water?

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mangrove roots” by eric molina licensed by CC by 2.0

Salt water can kill plans so the mangroves extract the freshwater from the salt water. Many species of mangroves survive by filtering as much as 90% of the salt found. Some of these species excrete salt through glands in the leaves.  Some mangrove species store salt in their older leaves and bark. When the leaves and bark shed, so does the salt that is stored in them.  They store the fresh water in their thick leaves. Another interesting fact about mangroves is that they will grow roots that stick out of the water..its like a snorkel for the tree, this is how they breath. These breathing tubes are called pneumatophores.

 

Why do they matter?

Mangroves, seagrass beds, and coral reef work together. The trees trap sediment and pollutants that would flow out into the sea. Seagrass beds provide another barrier to slit and mud that could smother the reefs. The reefs protect the seagrass and the mangroves from strong waves. Without mangroves this ecosystem would collapse.

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Virgin Islands 2015” by dirksevet licensed by CC by 2.0

Mangroves provide many species with breeding grounds. Some of these species include shrimp, crabs, barracuda, tarpon, and snook. These species will find shelter in the mangroves as juveniles and then these organisms head out to seagrass beds as they grow and then eventually they will move to the ocean when they are adults. These trees provide a habitat to thousands of species, from bacteria to barnacles to Bengal tigers. These forests also attract birds which take cover in the branches. They are a perfect for nesting sites for hundreds of migratory bird species. Additionally, the leaves that fall from the trees provide nutrients to invertebrates and algae!

 

Threats to mangroves

Shrimp farming is by far the biggest threat to the world’s mangroves. Many acres of wetlands have been cleared to make artificial ponds for shrimp. Shrimp farmers dig channels of water to supply these ponds with ocean water. These water channels alter the natural flow of water that maintain the mangroves as well as other ecosystems. Diverting the water from mangroves can hurt them by preventing their seeds from being dispersed, and it can kill them by cutting off fresh water supply. Agriculture is also another threat to mangroves. Thousands of acres have been destroyed for rice paddies, rubber trees, and palm oil plantations. Farmers use fertilizers and other chemicals that runoff into the water supply. Although mangroves are resilient mangroves can only tolerate so much.  Of course coastal development is another huge threat to mangrove forest. Ports, docks, hotels, gold courses, and marinas are being built which is taking away from the mangroves.

 

Mangrove Conservation

There are many different projects going on that address the conservation of mangroves. For example the mangrove watch that looks at Australia’s mangroves. The mangrove action project is another group that takes a bottom-up approach to mangrove conservation and restoration issues. Here is an interactive case study about mangrove conservation. It is pretty neat, check it out!

Here is a video from the mangrove action project on shrimp farming, check it out!

Check out Melissa’s post on mangroves!

Reef Conservation Groups

There are plenty of different organizations that want to help protect the coral reefs. In this blog I will talk about a few of the organizations that are working to help conserve the reefs.

Coral Reef Alliance

This organization was found in 1994 by Stephen Colwell. He wanted to engage the dive community in protecting coral reefs that were significantly declining due to human activities. This program is called CORAL and takes a multi-purpose approach to restring and protecting coral reefs. They work with communities living near the reefs. The work to reduce local treats to reefs. These include over fishing poor water quality, and unsustainable development. They help communities befit socially, culturally and economically from conservation.  CORAL also works directly with the tourism industry to decrease its environmental footprint and they also work to educate the visitors about the importance of coral reefs. If you want to learn more about the Coral Reef Alliance and their program CORAL please go to their main page.

Check out this video!

NOAA Coral Reef Conservation Program

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NOAA” by Wikimedia Commons licensed by CC by 3.0

This program was established in 2000 by the Coral Reef Conservation Act to protect, conserve and restore the nations coral reeds by maintaining a healthy ecosystem. This organization focuses on impacts from the top three global threats to reefs. This includes- climate change (and ocean acidification), land based sources of pollution, and unsustainable fishing practices. This program brings together expertise from across NOAA for studying these complex ecosystems. This program works closely with NOAA scientist in the National Ocean Service, National Marine Fisheries Service, Office of Oceanic and Atmospheric Research, and National Environmental Satellite, Data and Information Service. Want to learn more about this group? please click here.

Coral Guardian

Coral Guardian helps out reefs by developing the biodiversity of marine ecosystems in Indonesia and repopulating damaged reef areas. This program developed in 2010, and they aim to promote innovative approaches to marine conservation and encourage sustainable patterns of development.  Their mission included four topics. Conservation, awareness, research and valorisation ( develop sustainable solutions to improve the livelihoods of local communities). Want to learn more? Go to their main page!

Check out their YouTube video channel!

Reef Check

This organization was found in 1996 and its duties are to help reserve the oceans and reefs which are critical to our survival yet are being destroyed. The  programs headquarters are in Los Angeles and has volunteer teams in more than 90 different countries and territories. Reef check works to help tropical reefs and California rocky reef through education research and conservation. Want to learn more about this organization? Click here!

Watch this video about them!

Oceana

This program wants to make our oceans rich, healthy, and abundant again. Found in 2001, Oceana is the largest advocacy organization that is focused on solely ocean conservation. They want to identify practical solutions to use and then apply them. To learn more about this program, visit their home page.

 

Check out Marisa’s post about conservation group too!

Coral Bleaching

What is Coral Bleaching?

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Coral bleaching in the Gulf of Thaialnd_01” by Eco Cafe’ Phuket licensed by CC by 2.0

warmer water temperature is what causes coral bleaching. When the water is too warm, corals will expel the algae (zooxanthellae) living in their tissues. Corals have a symbiotic relationship with these algae. This means that the organisms depend on each other for survival. The alga produces food via photosynthesis for the coral. When ocean temperatures rise the corals expel the algae. This will cause a coral to turn completely white. When a coral bleaches it is not dead, they are under more environmental stress which can lead to a dead coral. Global warming is a big cause of coral bleaching but other environmental factors plays a role too.

Why is this a big deal?

Coral reefs may not be a huge portion of the oceans (They actually only make up less than 1% of the sea). But they are an important player in the ecosystem. These majestic reefs shelter the marine species that inhibit the ocean. More specifically they shelter about 25%  of marine species. The reefs also protect shorelines from waves, storms, and floods.  Reefs support the fishing industries, and they could also be the next big thing for medical breakthroughs.

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Clown Fish” by Ian Russell licensed by CC by 2.0

What species are affected by this?

Butterfly Fish

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Butterfly Fish” by Riz Warker licensed by CC by 2.0

This species munches on coral polyps. If their food source disappears survival of this species does not look good. Butterfly fish assist in keeping algae from covering the corals.

Spiny lobsters

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Spiny lobster” by Diverbelow licensed by CC by 2.0

Spiny lobsters rely on coral reefs for protection, especially during molting episodes. Spiny lobsters are a predator of sea urchins, which feed on kelp forests and can destroy them is populations are not predator controlled.

Hawksbill Sea Turtles

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Hawksbill sea turtle” by Raymond™ licensed by CC by 2.0

All sea turtles would be affected by loss of corals but the Hawksbill sea turtles are highly dependent on coral reefs. These turtles main food source is sponges. They also play a role in helping cycling nutrients from ocean to land, and they also help maintain healthy sea grass.

Coral Mining

…Yes that is correct, coral can mined. Personally, I did not believe it when I was looking into this topic. But yes, coral mining is a threat the coral reefs around us. You are probably wondering, what is coral mining and what are the effects that come along with it, and I am here to tell you! Coral mining is when live corals are taken out of the water and are used for other purposes like bricks, road fill, or cement for new buildings. Corals are mined for new buildings because they contain limestone and they are also used for other construction material.  Dead corals can be mined for calcium supplements or harvested for souvenirs or jewelry; corals can also be harvested for marine aquarium industry. Corals are also being harvested for medical usage.  Researchers have been using coral for bone graph clinical trials.

How Do They Get The Coral?

The people who actually mine coral do it either one of two ways. They will either do it manually, or by using dynamite. If a worker is trying to annually mine coral they will ion bars and sledge hammers to break up the larger corals into more manageable ones to bring to shore, or to put on a boat. If they are using dynamite to mine the corals, they will blast the section they want which will break up the corals into smaller pieces so it can be brought to shore. This has a bigger effect on larger areas of the reef they pick.

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jesse beazley’s reef- dynamited corals” by q phia licensed by CC by 2.0CC by 2.0

Impacts To The Reefs

The biggest effect of coral mining is that is causes a loss in biodiversity. By taking out chunks and rock from the reef, substrate is lost. Any coral polyps that come to the area cannot attach themselves to a structure thus the process is decreased. The reef won’t be able to grow larger in that area if coral polyps cannot become attached anywhere. Sedimentation occurs while the workers are mining the corals; the process of removing the corals causes disturbances to the sea floor and leave remnants behind.  Sedimentation can affect any of the benthic animals that reside here.

Coral reefs protect the land from storms and natural disasters. When a reef is partially removed or completely removed the shore becomes more vulnerable to storms and natural disasters. These effects can cause the land to retreat and impact the safety of any remaining parts of that reef section.  This will cause erosion. Locations around the world that have corals reefs are used for a source of food and tourism. The tourism industries have been negatively affected by mining. This is because for every ten dollars that is made from mining the community actually loses roughly two hundred and fifty four dollars.

Where Does It Happen?

Coral mining takes place anywhere coral is available, any locations hat have shallow water. Mining usually occurs at low tide when it is easier to gather coral. There are prominent locations for mining these includes The Barrier Reef, the Maldives, Panama, Indonesia, and East Africa.  Many of the reefs in these areas are protected under Marine Protected Areas now.

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Coral reef in the maldives” by inka.cresswell licensed by CC by 2.0

 

 

Reef Distribution

Reef Formation

Fringing Reefs: Grow near the coastline around different islands and are separated from the shore by narrow shallow lagoons. These reefs are the most common reefs that are seen and are located in the tropics.

Barrier Reefs: These reefs are also parallel to the coastline but are separated by wider deeper lagoons. These reefs can reach the water surface creating a “barrier”.

Atolls: These types of reefs are rings of reef that create protected lagoons. These reefs are usually in the middle of the ocean. Atolls are usually formed when islands surrounded by a fringing reefs sink into the sea or the sea level rises around them (these islands are often the top of volcanoes).

Patch Reefs: are reefs that grow up from the bottom of the island, platform, or continental shelf. These types of reefs usually occur between fringing reefs and barrier reefs. These types of reefs vary greatly in size and do not touch the surface of the water.

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Atoll forming” by Wikimedia Commons is licensed under CC by 2.0

 

Caribbean Coral Reefs

Caribbean coral reefs have a very unique collection of coral species. These include stony corals and many native species also. Some of these species are very high in commercial value. Most of the coral reefs  in the Caribbean Sea are fringing reefs. These reefs are very well developed and are located in a few different places like the coasts of Cuba, Jamaica, and the east coast of Andros Island in The Bahamas. The smaller islands also have fringing reefs that surround them. These islands include The Bahamas, Aruba, Bonaire, and the Cayman Islands. These reefs are shallower and provide some great Caribbean scuba diving and snorkeling opportunities. The Caribbean Sea also houses two “true” barrier reefs. The Belize reef is roughly 300 kilometers (186 miles!!). This is a section of the Mesoamerican Barrier reef system which is 900 kilometer (560 miles!!) long. Another barrier reef is located off the the east of Nicaragua. The Caribbean Sea has a very rich marine habitat more than any other in the Atlantic ocean. There are about 65 species of corals and 500-700 reef fish that live in these reefs!

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Belize Aerial 16” by Heath Alseike licensed under CC by 2.0 

Red Sea Coral Reefs

These corals reefs are in the Indian Ocean! Fringing reefs are really common in this area. The fringing reefs platforms are nearly 5000 years old and the reef complex itself is 2,000 kilometers (1,240 miles!!!) of shoreline. Many of the reefs grow directly from the shore line. The most dominant and active coral in this complex is the Acropora and Porites. There are also many offshore reefs in the red sea. There is also atoll rings of coral ridges that rise from the ocean, red sea coral formation is the result of tectonic forces. There are no “true” barrier reefs in this region. The red sea has a lot of features that distinguish it from the other reefs.  The corals here have developed a high tolerance to extreme temperatures, salinity, and occasionally turbidity (this would be caused by a dust storm that is relevant in this area).

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Porites Fragment” by Umijin licensed under CC by 2.0

Indo-Pacific Reefs

The Indo-Pacific Ocean is a huge area that covers almost half the Earth’s surface.  This region contains all three major types of reefs; Atolls, barrier, and fringing reefs. In this region there is a presence of an algal ridge. These are very rare in the caribbean region. The Indo-pacific reefs also often have extensive reef flats composed of consolidated coralline sands. This feature is rarely seen in the Caribbean region. The center of biodiversity for these reefs comes from the coral triangle.  The father a reef is from this triangle the less species it will have.

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The shallow hard coral reefs of the Indo-Pacific provide the habitat for a panoply of tropical fish.” By ZEISS Camera Lenses licensed by CC by 2.0