Coastal Lagoons: Important Ecosystems

Coastal lagoons are parts of the Earth’s coastline, where the ocean meets the land. They are important zones both for living things and for our economy. Coastal lagoons contain various kinds of habitats that provide homes for many animals and plants. Thus, they provide many valuable natural resources to people living and working in those areas. In this article, we describe what makes coastal lagoons attractive and important to plants, animals, and people. We also give examples of human activities and pressures that disrupt the lagoons close to where people live. Despite the damage human activities can cause to coastal lagoons, if countries respond with the right management measures, we have hope that the condition of coastal lagoons can improve, so that they will exist long into the future.


WHAT ARE COASTAL LAGOONS?
A coastal lagoon is a shallow body of water along the coast, which COASTAL LAGOON Coastal lagoon is a shallow body of water along the coast, is separate from the ocean but connected to it by one or more inlets. is separate from the ocean but connected to it by one or more inlets INLET Inlet is an indentation of a shoreline, usually long and narrow and means an entry.
( Figure A) [ ]. The lagoon that surrounds the city of Venice, in Italy, is a good example. Coastal lagoons range in size from . km² to , km² and they are found along % of the Earth's coasts [ , ]. For example, the Ria Formosa lagoon in Portugal, where our institute (CIMA) is based, covers an area of km .

CHARACTERISTICS OF COASTAL LAGOONS
Lagoons are commonly found along coasts. They are shallow-< m deep-and the water is -mixed by waves and currents. Coastal lagoons are found all over the world. Figure shows examples of lagoons in the Mediterranean region, where we live and work. Venice Lagoon, also known as the "Queen of the Adriatic" and the "Floating City," is one of the world's most famous lagoons. Venice is known for its natural beauty, architecture, and artwork. There are main types of coastal lagoons [ ]. Choked lagoons form along coasts where there is high wave energy. They have a single long, narrow entrance channel ( Figure A). Restricted lagoons may have several channels or inlets. They consist of a large, wide water body, usually parallel to the coast ( Figure B). Leaky lagoons are elongated water bodies parallel to the shore, with many ocean entrance channels. They form along coasts with strong tidal currents ( Figure C).

HOW DO HUMANS USE LAGOONS?
Lagoons are home to many species of plants and animals. For instance, there are more than species of aquatic plants and species of fish in Mediterranean coastal lagoons. This biodiversity makes coastal lagoons attractive places for to humans to carry out many recreational activities and to find food. Important activities include fishing, aquaculture, agriculture, tourism, boating, and building marinas and AQUACULTURE Aquaculture is a controlled cultivation of aquatic organism such as fish and shellfish, and other organisms. harbors ( Figure A). For instance, more than , people in the Sacca di Goro region of Italy work in aquaculture [ ]. Faro International Airport was built on land reclaimed from the Ria Formosa Lagoon, so that tourism could develop in the region. Furthermore, many people (like us!) find lagoons to be nice places to live and relax!

LAGOONS ARE UNDER PRESSURE
Human activities can result in multiple pressures on coastal lagoons. Example of these pressures include underwater noise from boat engines, pesticides from surrounding agriculture, pollutants from industrial facilities, and the conversion of lagoons into land, which is called land reclamation ( Figure B). There are many examples of how

LAND RECLAMATION
Land reclamation is a process of creating new land from the sea. changes in land use have a ected lagoons. For example, the switch to rice production in Sacca di Goro (Italy) led to an increase in the amount of nutrients flowing into the nearby lagoon. Sometimes, the ways land was used in the past have long-lasting consequences. For instance, mining activities stopped many years ago in areas surrounding the Mar Menor Lagoon (Spain), however, there is still metal pollution in the lagoon from those mining activities.

Human activities and pressures can change lagoon ecosystems [ ].
There are many examples of this. Construction projects can modify the shape of a lagoon's inlet, which can alter the water exchange between the sea and the lagoon. Construction of ports or structures called groynes can change the way waves hit the shoreline near parts GROYNES A shore protection structure built perpendicular to the coastline. of a lagoon, which can cause erosion. Erosion can increase the risks EROSION Erosion is geological process in which earthen materials are worn away and transported by natural forces such as wind or water. of flooding and storm damage, which may a ect humans. Changes in water quality can also lead to changes in the lagoon ecosystem. For example, if the ecosystem of a coastal lagoon is damaged, this can cause important fish to die, which can a ect the fishermen who work there and the people who normally eat the fish they catch. There are numerous other examples of ways that degradation (breakdown) of lagoons can impact human welfare (  Mar Menor (Spain) Jellyfish blooms a ect tourism, especially swimming.
Nador (Morocco) Aquaculture activities were stopped in due to pollution. This impacted the availability of seafood and caused loss of % of local jobs.

Farwa (Libya)
Mercury contamination from a nearby oil company was detected in fish and oysters. This is a serious health risk to those who eat these organisms.

Burullus (Egypt)
Changes in salinity and chemical pollutants have a ected fish diversity, causing a decline from to species. [ , ], and the SouthMedLag project studying North African lagoons. The SouthMedLag project (short for South Mediterranean Lagoons), analyzed North African lagoons in Morocco, Algeria, Tunisia, Libya, and Egypt, of which were studied in detail [ , ]. The research was conducted by African and European scientists to assess the North African lagoons and provide management solutions.

THE FUTURE OF LAGOONS
The Earth's population is growing, temperatures are getting warmer, normal weather is being replaced by unusual storms, and sea levels are rising. Climate change is real, and all these changes will a ect lagoons worldwide. As scientists, we believe that coastal lagoons will exist for years, but their features will change rapidly over the next  . doi: . /frym. .

CONFLICT OF INTEREST:
The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
COPYRIGHT © El Mahrad, Newton and Murray. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

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