Urbanized coastal lagoons in the age of climate change

A coastal lagoon is defined and described as:

“A body of water separated from larger bodies of water by a natural barrier. Coastal lagoons form along gently sloping coasts. They are generally shallower than atoll lagoons and tend to be separated from the ocean by an island, reef, or sand bank. Most of the time, coastal lagoons are connected to the ocean by an inlet.”
Source: https://oceanservice.noaa.gov/facts/lagoon.html

Given their shallow nature, coastal lagoons face a number of potential threats from climate change. These include, but are not limited to:

Increased water temperatures
Sea-level rise
Storm surge
Increased precipitation which can lead to erosion, pollution runoff, submergence of lagoon barriers, flooding, and potential drying of the surrounding wetlands.

In addition, the natural barriers that separate coastal lagoons from larger water bodies may limit the normal flushing of the waters within the lagoon, therefore increasing pollution from runoff within the lagoon’s catchment area. This could also lead to eutrophication from increased nutrient load in the lagoon.

Algae bloom in Indian River Lagoon – Source: ocenabites.org

For those coastal lagoons with large cities situated on them, other factors at play include land use and transportation development pressures, dredging for shipping channels, wakes created by shipping and boating activities, and for a surprising number of these twelve lagoons, threats from nearby fossil fuel drilling, refining, and related activities.

Below are satellite images of some of the most urbanized lagoons in the world. Bear in mind that other terms tend to be used for lagoons in various parts of the world, including “bay,” “lake,” or “river.” Large metropolitan areas located on coastal lagoons include:

Lagos, Nigeria = 21,000,000 – located on Lagos Lagoon
New York City, New York, USA = 20,870,000 – located on Jamaica Bay Lagoon
Maracaibo, Venezuela = 5,278,000 – located on Lago de Maracaibo
Abidjan, Ivory Coast = 5,152,000 – located on Ébrié Lagoon
Porto Allegre, Brazil = 4,406,000 – located on Lagoa dos Patos
Cotonou/Porto Novo, Benin = 3,700,000 – located on Lake Nokoue Lagoon
Venice, Italy = 2,600,000 – located on Venetian Lagoon
New Orleans, Louisiana, USA = 1,271,000 – located on Lake Borgne Lagoon
Kaliningrad, Russia = 800,000 – located on Vistula Lagoon
Szczecin, Poland = 777,000 – located on Szczecin Lagoon
Melbourne-Palm Bay, Florida, USA = 602,000 – located on Indian River Lagoon
Ciudad del Carmen, Mexico = 221,000 – located on Laguna de Terminos

Source: en.wikipedia.org

Ciudad de Carmen – Source: patiabierta.mx

Given the size of these metropolitan areas and the greater propensity for stormwater runoff and urban pollution, the coastal lagoons associated with these cities will be even more susceptible to the impacts from climate change listed previously in this post.

The twelve (12) lagoon images provided include:

Ébrié Lagoon in the Ivory Coast