Coast

What Exactly Is a Coast?

A coast – also called the coastline, shoreline, or seashore – is the land next to the sea or the line that forms the boundary between the land and the ocean or a lake. Imagine it as the edge of your favorite beach, where sand meets water. But did you know Earth contains roughly 620,000 km (390,000 mi) of coastline? That’s like wrapping a giant ribbon around our planet almost twice over!

The Influence of Topography and Water

Coasts are influenced by the topography of the surrounding landscape, as well as by water-induced erosion, such as waves. The geological composition of rock and soil dictates the type of shore that is created. Think of it like a painter choosing their palette – each coast has its unique colors based on the materials available.

Coastal Ecosystems: Biodiversity Hotspots

Earth’s coasts are important zones in natural ecosystems, often home to a wide range of biodiversity. On land, they harbor important ecosystems such as freshwater or estuarine wetlands. In wave-protected areas, they can host salt marshes, mangroves, or seagrasses that provide nursery habitat for finfish, shellfish, and other aquatic animals.

Rocky Shores: A Home to Sessile Animals

Rocky shores are usually found along exposed coasts and provide habitat for a wide range of sessile animals and various kinds of seaweeds. These rocky outcrops create a unique environment that supports life in the intertidal zone, where waves crash and tides ebb.

Tropical Coasts: Coral Reefs

Along tropical coasts with clear, nutrient-poor water, coral reefs can often be found between depths of 1–50 m (3.3–164.0 ft). These vibrant ecosystems are like underwater cities teeming with life, but they face threats from climate change and pollution.

Human Settlements and Coastal Importance

About 44% of the human population lives within 150 km (93 mi) of the sea as of 2013. This means that coasts are not just natural wonders but also critical for major parts of the global food and economic system. Think about it – every time you enjoy a seafood meal, chances are it came from coastal waters.

Coastal Defense and Economic Drivers

The coast is important for coastal defense measures to protect against military invaders, smugglers, and illegal migrants. Tourism is also a significant economic driver for many island nations, but growth management and coastal management can be challenging. How do we balance the needs of nature with human activities?

Coastal Ecosystem Services

Ecosystem services provided by coastlines include recreational activities such as swimming, fishing, and surfing. Emergent, concordant, and discordant coastlines are classified based on rock types and landforms formed by sea level changes and erosion patterns.

Coastal Management: Addressing Destructive Waves

Coastal management is necessary to address destructive waves such as swash and backwash, which can change shoreline configurations and move sediment over short periods. The relative strength of flow in swash and backwash determines what size grains are deposited or eroded, dependent on how the wave breaks and the slope of the shore.

Coastal Landforms and Features

Coastal landforms include cliff erosion, natural arches, sea caves, stacks, stumps, wave-cut notches, and wave-cut platforms. Gently sloping wave-cut platforms develop early in cliff retreat, decreasing in length as waves lose energy offshore.

Sediment Deposited by Rivers

Sediment deposited by rivers is a dominant influence on coastlines with estuaries, but human regulatory devices often block this sediment from reaching the coast. Coral reefs provide sediment for tropical island coastlines, ensuring that these ecosystems remain vibrant and healthy.

Coastal Threats: Pollution and Eutrophication

Pollution is a major concern, including marine debris, oil spills, and small vessel bilge water. Sustainable Development Goal 14 aims to preserve marine coastal ecosystems and support sustainable economic practices for coastal communities. The UN has also declared the 2021-2030 decade on ecosystem restoration, with insufficient attention given to restoring coastal ecosystems.

International Attention: Policies and Goals

International attention is focused on addressing coastal threats through policies such as preserving marine ecosystems and promoting sustainable practices. Coastal areas are subject to various impacts including pollution, sea level rise, erosion, and development. How can we ensure that our coasts remain healthy for generations to come?

Coasts are dynamic environments shaped by natural processes such as sea level rises, waves, and weather phenomena. They are not just lines on a map but living, breathing ecosystems that support life in countless ways. As we continue to develop and grow, it’s crucial that we understand the importance of these coastal zones and work towards their preservation.