Article**: Oceans and Wetlands.
Between Golden Bay and Tasman Bay at the northwestern tip of New Zealand's South Island, there are vast coral reefs that are beautiful and rich in biodiversity, providing shelter for small animals such as oysters and juveniles. In 1980, in order to protect bryozoans, the world's first bryozoan-based fishing exclusion zone was established, which extends from the coastline to a depth of about 50 meters into the ocean, covering an area of about 146 square kilometers
Auckland, New Zealand Source: Unsplash CC0 Public Domain
In 1983, the National Institute of Water and Atmospheric Research (NIWA) conducted a study on one of the coral reefs and found 37 species of bryozoans and 39 species of invertebrates, as well as a large number of fish. In 2008, a study comparing fishing and unfishing areas near coral reefs found that biodiversity was richer in areas where fishing was restricted
But,With the increase in human activity, land clearing for agriculture and forestry has led to a tenfold increase in sediment runoff in the area。These sediments are made up of loose sand, silt, and clay particles. Thick layers of silt piled up, destroying and burying coral reefs
A 2021 survey of the same area found flat mud deposits with the occasional small, dead bryozoan popping up in the sediment. There are no more fish here either.
In recent years, we have often heard stories of the oceans in trouble: warming waters causing marine heatwaves and coral bleaching; Fish and sharks appear where they have never been seen; Plastic particles are found in the stomachs of dolphins and penguins; Overfishing leads to a sharp decline in the population of species, and so on.
At the same time, sea levels are rising; Dredging and mining are destroying ecosystems; The noise and artificial light of underwater engines are changing the way animals behave; As carbon dioxide dissolves, so does the basic chemical composition of seawater.
WhileIn addition to these problems, there is another issue that is often overlooked: sediment runoff。When people cut down trees, build roads, and pile up paddocks, sand, mud, and silt flow into the sea.
Although the National Oceanic and Atmospheric Administration (NOAA) has described it as the single largest source of pollution in the world's waterways and coasts, the resulting damage to coastal ecosystems has received little attention. Silt turbidity can affect marine life, from the destruction of the algal canopy to phytoplankton changes.
Sediment runoff is most likely to occur in moist areas with high and regular rainfall, susceptible to storms and **, and most likely to occur on steep slopes and rocks and soils with fewer years. Agricultural land is also important for watercourse sediments**.
New Zealand has it every yearMore than 200 million tons of sedimentTransported by rivers to the ocean, fine sediment is the most widespread water pollutant in New Zealand. Although New Zealand covers only 0 percent of the global land area2%, but New Zealand's Ministry of Environment reported in 2018 that New Zealand contributes 17% sediment
Planting and avoiding runoff are the most obvious solutions。The roots of trees are an excellent way to hold the soil, and not only that, but they also direct water deep into the ground while removing carbon from the atmosphere.
New Zealand's current recommendation is to plant forests close to the top of the catchment area, where the ground is steep and the soil is fragile. New Zealand** is also working on projects such as the Billion Tree Project. At the same time, the New Zealand Building Research Association recommends managing construction projects to avoid runoff, including the use of sedimentation tanks and channels to retain dirty water, or the use of chemical "flocculants" to bind fine sediments together.
Individuals and families can plant gardens and trees to reduce bare land. They can limit the use of concrete and other impervious surfaces, or opt for permeable concrete. We need to see real action, by working together, to keep the soil on land and the ocean clean.
Text: Sara Review: Yanjun
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