Estuary Ecology

Estuary definition

A partly enclosed coastal body of brackish water where one or more rivers or streams flow into the sea, allowing freshwater and saltwater to mix. Brackish water has more salt than freshwater but less than seawater.

Mississippi River sedimentation process that created the delta over thousands of years

Natural flooding carried sediment (mud, silt, and sand) downstream. When the river slowed near the Gulf, the sediment settled out and gradually built the Mississippi River Delta. Today, levees and canals prevent much of this sediment from reaching wetlands.

Transept - similarities and differences to barrier island transept

Similar because both show habitats changing gradually across a landscape. Different because the estuary transept includes barrier islands, lagoons, salt marshes, freshwater marshes, swamps, and forests due to changing salinity, making it more complex than the barrier island transept.

Causes of marsh die-back in the estuary and re-habilitation strategies to combat it

Causes: saltwater intrusion, reduced sediment supply, levees, navigation canals, oil and gas canals, hurricanes, climate change.

Rehabilitation: freshwater and sediment diversions, marsh creation, beach and dune restoration, planting native vegetation.

How does marsh land loss affect the impact of storms?

Wetlands reduce storm surge and wave energy. Every 2.7 miles of wetlands reduces storm surge by about 1 foot. Losing wetlands allows storm surge to travel farther inland and increases flooding. Magnitude of the wetlands in southern Louisiana and magnitude of the loss

Bald cypress survival techniques in swamps

Aerenchyma tissue transports oxygen through flooded roots; develops a deep taproot and shallow horizontal roots that allow survival in oxygen-poor, waterlogged soils.

What affect do the following industries have on southern Louisiana, and the state as a whole, both the positive effect on the economy, and the negative impacts on the environment. Commercial Fishing

Positive: More than 70% of Gulf seafood landings come through Louisiana; nearly $2 billion annual economic impact. Negative: Depends on healthy wetlands, so wetland loss threatens fish populations and the industry.

What affect do the following industries have on southern Louisiana, and the state as a whole, both the positive effect on the economy, and the negative impacts on the environment. Sport Fishing

Positive: About 1.17 million anglers, $3 billion in economic output, and 22,820 jobs. Negative: Habitat loss reduces fish populations and recreational opportunities.

What affect do the following industries have on southern Louisiana, and the state as a whole, both the positive effect on the economy, and the negative impacts on the environment. Oil and Gas Production

Positive: Contributes about $73 billion to Louisiana's GDP and supports about 249,800 jobs.Negative: Oil and gas canals increase saltwater intrusion and account for an estimated 30–59% of Louisiana's land loss.

What affect do the following industries have on southern Louisiana, and the state as a whole, both the positive effect on the economy, and the negative impacts on the environment. Shipping including Maritime Jobs

Positive: Louisiana ranks #1 in waterborne commerce, moves about 500 million tons of cargo annually, and provides over 54,000 maritime jobs. Negative: Dredging, navigation canals, and levees alter natural river flow and reduce sediment reaching wetlands.

Hurricane Katrina: What caused the extent of the damage and who was found responsible?

Extensive wetland loss, subsidence, and levee failures allowed catastrophic flooding. The U.S. Army Corps of Engineers was found responsible for engineering failures discussed in class.

New Orleans' Post-Katrina Flood Defenses. Who built them and how were they designed to protect for the kind of impacts that caused the extreme damage from this hurricane.

Built by the U.S. Army Corps of Engineers as the Hurricane and Storm Damage Risk Reduction System. Designed for a 100-year flood event using levees, surge barriers, floodgates, and massive pumping stations.

The Lake Borgne Surge Barrier

Nearly 2 miles long and 26 feet high, built to block storm surge from reaching New Orleans and the Lower 9th Ward; nicknamed the "Great Wall of Louisiana."

Seabrook Floodgate Complex

A major floodgate structure that works with levees and surge barriers to prevent storm surge from entering New Orleans.

Lower 9th Ward – what caused the extent of damage and delays in rebuilding?

Severe flooding from levee failures, delayed levee repairs, prolonged flooding, slow restoration of utilities, and a much slower recovery than most New Orleans neighborhoods.

2017 and 2023 Coastal Master Plan - Louisiana Comprehensive Master Plan for a Sustainable Coast (only points reinforced in class)

A 50-year, multi-billion-dollar coastal restoration plan focused on sediment diversions, marsh creation, and restoring Louisiana's coast to reduce future land loss.

Port Fourchon – it's role in the oil industry in Louisiana

Services over 90% of Gulf of Mexico deep-water oil production, supports more than 400 supply vessels daily, and helps support about 18% of the U.S. oil supply.

Sediment diversion strategies – how (and how well) do they work?

Controlled openings in levees divert freshwater, sediment, and nutrients from the Mississippi River into wetlands. They reduce saltwater intrusion and help rebuild marshes, but restoration is gradual and cannot instantly replace lost land.

Lessons from experience with the Caernarvon and Davis Pond sediment diversion sites

Freshwater diversions successfully reduced salinity and improved wetlands. Although not originally designed to build land, the Caernarvon Diversion created about 1,000 acres of new land, showing diversions can aid restoration.

Caminada Headland Beach and Dune Restoration - similarities and difference between dune restoration on the gulf shore and east coast barrier islands

Similarities: Both restore dunes to reduce storm damage and stabilize shorelines. Differences: Gulf restoration uses offshore sand, retention dikes with tidal openings, and native plants such as black mangroves to rebuild Louisiana's rapidly eroding coastline.

Ecosystem services – definition, categories, and the relative difficulty of assigning monetary value to the different categories

Definition: The benefits people obtain from ecosystems. Categories: Supporting, Provisioning, Regulating, Cultural. Monetary value: Provisioning services are easiest to value economically, while supporting, regulating, and especially cultural services are much more difficult to assign a dollar value despite their importance.