Human Impacts & Coastal Zone Conservation

Objectives• The state of Beach Ecology• Factors impact sandy beaches• Coastal zone management• Beach nourishment & beach ecology• Disadvantageous

• Size of the project & sand Volume• Type of sand• Beach Morphological profile• Nature of dredged sand

• Best Management to practice

The State of Beach Ecology• Beaches are alive (why)?• Home to: birds, grasses, crabs, clams, fish, tiny invertebrates, and

more.

• These habitats are suffered of human impact (explain)• On the landward side by coastal development • on the ocean side by sea level rise and coastal erosion.

• Beach ecosystems are affected by many different types of human pressures, from recreation to pollution to coastal engineering, grooming, off-road vehicles (OR’V), exploitation.

•

As a coastal ecosystem, the beach is underrepresented in science and largely unrecognized in management practices. (explain)

The Coastal Zone Management Act calls for “The protection of natural resources, including beaches, dunes, barrier islands , fish and wildlife, and their habitat, within the coastal zone”. State of the Beach revealed that despite this federal mandate, sandy beaches all around the nation are receiving little, if any, ecological protection. Therefore, coastal managers must make three key changes with respect to sandy beach ecology:1- There must be widespread recognition of the beach as a natural ecosystem,2- Managers need to better incorporate existing science into beach management,3- Research in beach ecology must advance.

A variety of anthropogenic and other external factors that impact sandy beaches on various temporal and spatial scales:

Pollution, recreational activity, expanding human populations,& development.

Natural processes, such as storms, hurricanes, and tsunamis can also have dramatic impacts.

Structures that change the landscape and modify geological processes, and global change all affect beaches..

Factors impact sandy beaches

Sheltered Beaches vs exposed Beachesand human impacts

Sheltered BeachesMost sensitive to pollution under low-energy or sheltered conditions because pollutants are not easily dispersed.

Exposed Beaches Most sensitive to disruption of their sand budgets because of the large volumes of sand transported under high-energy conditions.

Human activities tend to have more impact on dunes and dune vegetation and effects are more severe under more dynamic or exposed conditions.

The chief long-term threat facing sandy shores, worldwide, is loss of habitat resulting from increasing erosion attendant on sea-level rise, and changes in storm patterns

Coastal zone ManagementWhy Management?The main purpose of management is conservation of the habitat and/or the target species.

Due to huge human pressure and development, coastal zone management is concerned with managing for multiple uses:

1- Limiting the impacts of development, 2- Ensuring sustainability, 3-Maintaining key processes, such as sediment transport.

The central feature of coastal zone management of soft coasts is providing access for recreation on beaches while limiting damage to the dunes. Identify Soft coasts

Properties of soft coasts highly relevant to coastal zone management are: They are the fragile marine ecosystems

1- Their malleability (softness/ flexibility).2- Their temporary stabilization by plant growth in dunes.3- Their sensitivity to disturbance.

Soft coasts consist of beaches, dunes, surf zones, and estuaries, which exchange sediment and form a single geomorphic system of sand storage and transport.

Movement, exchange, and storage of sediment in this system are mostly driven by water movement that is the most important process.

Beach Nourishment and Beach EcologyWhat is Beach Nourishment?Beach nourishment, known as beach restoration or beach fill.It is a coastal management strategy where sand is retrieved from a marine or land “borrow site” and deposited onto the beach.

Why Beach Nourishment? Coastal managers use beach nourishment to:1- Combat coastal erosion.2- Protect coastal infrastructure.3- Widen the beach in order to increase revenue from recreation.

TodayBeach nourishment is environmentally preferred erosion response compared to using hard structures such as seawalls. ( What do you think?)

Case Study (Florida’s Beaches)For many years ago, Florida suffered from increasing levels of coastal erosion. Naturally, Florida had few inlets. Many more inlets were constructed By Florida State.What are the consequences? These additional inlets disrupted the natural transport of sand along the coast, depriving many beaches of their sand supply. Sea level rise and stronger storms due to climate change have eroded away more sand. Beaches naturally respond to erosion by migrating landward.

However, much of Florida’s coastline has been developed right up to the beach; as the beaches erode, they have nowhere to migrate and instead disappear. In order to combat this loss of sand and protect coastal structures, Florida has turned increasingly to beach nourishment.

Disadvantages:

Beach nourishment can be highly stressful to both nearshore and sandy beach habitats. (Why?)

1-Florida’s native beach sand is a quartz-carbonate mixture and is added to the littoral system from land based sources.

There is only a small natural supply of this sand, not enough to satisfy the needs of the many nourishment projects that have and will occur.

Portions of Florida are running out of compatible sand.

In spite of this limited supply, Florida continues to use beach nourishment as the preferred erosion control option.

Many of Florida’s beach nourishment projects have had unpleasant results for beach ecology.

1- Size of the Project and Volume of Sand

The nourishment project is covering a long stretch of beach and using a large volume of sand (1.2 million cubic yards of sediment dredged from offshore to fill a 1.4 mile stretch of beach). YARD= 91.4cm= 3feet.1-Organisms that live on the sandy beach are biologically adapted to survive a wide range of conditions, including the movement of sand. However, the vast majority of beach organisms cannot survive the extreme burial depths caused by nourishment projects. The burial of sand crabs and beach clams during beach nourishment projects sharply depressed their population numbers even 10 weeks after the project. (Why?)These organisms are not adapted to survive the sudden dumping of several feet of sand on top of them. Projects that cover a large area take much longer for beach organisms to recolonize than smaller scaled projects .

Therefore, the size of the project and volume of sand alone probably depressed population levels on the beach for several months.

2-Type of Sand

Type of sand is another significant problem

This sand was dredged up from an offshore sand bar, which has a very different kind of sand that naturally found on Florida’s beaches.

Changing the sand’s size, color, shape, or composition alters the habitat, decreasing the ability of organisms to survive.

Sand coarser than the native sand results in decreased abundance of invertebrates.

Sand finer than native also causes decreased species abundance and diversity.

Fine sediment will also remain suspended in the water, making filter feeding more difficult for sessile invertebrates and decreasing the ability of surf fish to see their food.

Sand Color:The new sand was also the wrong color: a gray-black instead of tawny brown. Even a change in sand color can change important ecological functions.

For example, 1-The gender of turtles is influenced by the temperature of the sand in which the embryos develop. Darker sand will be warmer, and will cause a disproportionate number of eggs to develop as females.

2- A change in sand temperature can also affect the physiology of smaller invertebrates, so that they have to work harder to burrow in the sand.

3- This pressure can make survival more difficult, ultimately decreasing the number of living organisms on the beach.

Sand ContaminationsSediments that contain contaminants are also unsuitable, as the toxic material will negatively impact the organisms that live on the beach.

Sand with a large amount of shell fragments decreases burrowing ability and impedes the foraging behavior of surf fish and shore birds.

Sand Cementation occurs when the sand contains large amounts of dissolved shell fragments, causing a hard, cement-like layer on the top of the sand.

Animals are not able to break through this layer, and will remain trapped under the sand or be unable to forage at the surface.

3- Beach Morphological Profile

The morphological profile of the beach created by a nourishment project was a problem. Many construction projects create a beach profile much different than the original beach.Result in a permanent shift in the biological community structure .

The spatial pattern of beach organisms depends greatly on the native slope of the beach, so a significant disturbance in this profile results in a significant disturbance in beach ecology.

Nourished beach will often form a scarp (steep slope or cliff), or steep drop, at the water’s edge for several months before the new sediment equilibrium is reached.

The scarp can be several feet high, making it too difficult for nesting sea turtles to climb onto the beach. How does the beach Scarp affect living organisms?

4- Nature Of Dredged Sand

The dredged sand had a different composition from the native beach sand. The native beach sand (Florida) originated on land and is composed of a quartz-carbonate mixture.

The dredged up sand from offshore marine areas composed of carbonate skeletal fragments with delicate, fragile designs.

These fragments readily break down into fine sediments when exposed to wave energy, weathering into an unsuitably small sand size for the beach.

This incompatible sand did not survive the natural forces on the beach.

For example,Couple of tropical storms that eroded the beach extensively. Within a year, the new sand had washed off the beach, eliminating any positive effects of the nourishment.

Best Management To Practice• Damage to the sandy beach ecosystem cannot be avoided

completely in nourishment projects, but it can be decreased significantly with careful planning.

• A proposed set of best management practices is covering the elements of sediment choice, timing, sand placement methods, site-based design, monitoring, and minimizing conflicts of interest.

• 1- Sediment choice: the sediment used should be as close as possible to the native sand, in terms of grain size distribution, color, and composition.

• 2-Timing: The project should be completed before the start of the warm season to improve chances of invertebrate recolonization.

• 3-Sand placement methods: The sand should be placed to mimic the natural beach morphology so that the sediment equilibrium is reached quickly.

• 4-Site-based design: Each beach is different, so each project should be designed individually with that beach’s unique features in mind.

• 5-Monitoring: Ecological monitoring should be conducted before, during, and after construction to best understand the extent to which the beach ecosystem changes.

• 6- Minimizing conflicts of interest: The project design period should be transparent and include opportunities for public comment.