(HAO) Human Impact on the Ocean Lesson

Human Impact on the Ocean

Human recreation and transportation can greatly impact marine ecosystems. We can take measures to reduce these impacts.

Movement of Invasive Species

Picture: Green mussels growing on a navigational buoy. If too many grow on the buoy, they can weigh it down and sink it.

Both recreational and commercial ocean-going vessels can facilitate the movement of non-native species, moving them from their native habitat to other habitats, where they will likely have no native predators.

Picture: Diagram showing the water pollution of the seas from untreated ballast water

Large cargo and cruise ships have an area called the ballast. This is an area of the ship that keeps the ship at an appropriate level in the water. For example, if a ship is leaving a destination to pick up cargo, it might be empty, which would make the ship much lighter, and therefore, more likely to sit too high in the water. So, to combat this and to add weight to the ship, water is pumped into the ballast area of the ship to weigh it down, so the ship will sit better in the water. Once the ship reaches its destination, the ballast water is pumped out so the ship can take on cargo. Ballast water is typically not filtered before entering the ship, so it contains any micro-organisms or larval organisms in the water. When the water is pumped out at the destination port, this water can release organisms that are not native to that area. Some ships can have ballast from multiple areas, so when the water is eventually pumped out, the organisms from all of the areas are pumped into the port of discharge

These species can take hold and grow in this new environment and can even grow out of control, out-competing native organisms because they have no natural predators and their prey have no defenses against these new organisms.

Recreational vessels can also facilitate the movement of non-native species. Often, recreational boats are taken out of the water in one area and moved to another body of water. If these boats are not washed between bodies of water, they can also transport species between bodies of water. This frequently happens with freshwater boats, but can also happen with ocean-going vessels.

Water Pollution

Grey water is water that comes from sinks, laundries, showers, galleys, and other sources of water. This water is not as dirty as sewage water, but it is not exactly clean either because it can have chemical, soap, mineral, and metal residues. Grey water from a ship is released into the ocean. For example, a cruise ship can release around 1 million gallons of grey water in a single weekly trip. While large ships can produce large amounts of grey water at a time, smaller, recreational vessels can also release grey water.

On a ship or boat, the bathroom is called the head. Large and small vessels that have a head can also produce sewage pollution. On large ships, they can have a sewage treatment plant, but small vessels do not. There are regulations that prevent people from discharging sewage into coastal waters, but these regulations are not as easily enforced in international waters. Sewage water, known as black water, is emptied into the ocean from large ships. A cruise ship, for example, can release around 210,000 gallons of human sewage into the ocean during a weeklong cruise.

Noise Pollution

Most powered marine vessels are quite loud. Recreational vessels can have multiple loud motors. Shipping, cruising, and energy exploration can also produce large amounts of noise.

This noise can disrupt marine mammal communication. Whales and dolphins can have difficulty communicating with each other and finding food. Fish are also affected by noise. If an area is too loud, fish will not live in that area and will either move somewhere else or die.

Scientists are currently actively researching noise and its effects on marine environments.

There are other ways that recreation and transportation can affect the oceans, such as pollution from fossil fuels used to power these vessels, but these are three very important effects these types of vessels can have on marine environments.

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