Have you ever seen a piece of wood washed up on the beach? Or maybe floating down a river? That wood is on a long and important journey. Let’s follow that journey and learn about all the amazing places the wood visits along the way!
Driftwood logs are the trunks and branches of trees that grew next to a river and then fell into the water. These logs make a journey from the forest, all the way to the bottom of the ocean.
When a piece of wood falls into the water, it is called driftwood. These driftwood pieces are carried by the river water and become tangled together in large groups called logjams. These logjams can clog the river for a short time, or a very long time. Some logjams can be hundreds of years old!
One of the oldest logjams ever known was the Great Raft in Louisiana’s Red River. It was thought to have existed for approximately 1000 years. The Great Raft was sacred to local Native American tribes, and it caused floods that would help keep the local land fertile. In the mid-1800s the Great Raft was destroyed so that steamships could travel down the river to New Orleans.
What Happens to Wildlife When a Logjam Clogs Up a River?
When logjams form, they force the river to slow down. This helps the smallest animals in the river find more food. Rivers carry microscopic pieces of food called organic matter. If a river flows too fast, the small animals at the bottom of the food-chain, like freshwater mussels, cannot catch this food. Rivers slowed down by logjams give these small animals more time to eat the organic matter before it travels to the ocean.
When these animals eat more organic matter, their population gets bigger! Larger animals like fish and insects eat them, and even larger animals at the top of the food chain, like bears, go on to eat those animals. When logjams clog up a river, there is more food for everyone in the river ecosystem!
Sometimes the driftwood will rot and be eaten by decomposers. Other times, plants may grow on the logs. Insects will even lay their eggs on the wood. When the eggs hatch, some larvae are eaten by small fish. These small fish hide from predators between the driftwood logs and would be in danger without their protection.
When driftwood logjams are removed, a river ecosystem cannot support as much life. In healthy forests, 70% of all driftwood nutrients stay in the river ecosystem. The other 30% continue downriver towards the ocean, where driftwood has more important roles to play!
How do you Build a Coastline with Driftwood?
Coastlines are places where the land and ocean meet. Here you may find beaches and wetlands, as well as marine animals and plants.
When waves approach the coastline, they hit it very hard. These strong waves can break away sand and soil if the coastline is not protected. One way to protect a coastline is to let driftwood pile up. The driftwood absorbs the hard force of the waves and does not let sand and soil escape.
These piles of driftwood also trap sand and soil floating in the water. This creates new coastline that can become new places for plants and animals to live.
Many of the coastlines around the world have been shaped by this process. In North America, the Pacific Northwest is a good example of an area that has had its coastlines shaped by driftwood for thousands of years.
Coastlines and rivers had a lot more driftwood in the past than they do today. Driftwood can damage boats, so it is removed from the water for safety reasons. The wood is also profitable, and is collected and sold to build structures like houses.
There is some driftwood that does not wash up on the beach. It escapes the coastline and floats directly into the open ocean. Out there, it has another very important role to fulfill!
What Kind of Animals Live in Driftwood Reefs?
When driftwood travels out into the ocean, it can float for up to 17 months. During this time, it travels on ocean currents, and may even be frozen in large chunks of ice. Ocean currents are strong flowing ‘rivers’ of water within the larger ocean. These currents will flow on the ocean’s surface when the water is warm, and sink down into the ocean’s depths when the water is cold. When the current dives below the surface, the buoyant floating driftwood is left to collect in large driftwood reefs.
More than 200 species of wildlife are attracted to these reefs, forming a thriving ecosystem. In the open ocean, food is very rare, and there are few places for small fish to hide from predators. The structure of the driftwood gives small animals places to hide when they are in danger. Driftwood also becomes an important nursery for eggs and young fish.
Marine algae and bacteria grow and feed on the driftwood. This algae becomes food for crustaceans and small fish. These small prey animals attract large predators like tuna. Over time, a driftwood reef becomes a diverse, thriving ecosystem that provides more food and shelter than the surrounding ocean.
When the driftwood’s 17 months are up, it will lose its buoyancy and begin to sink towards the ocean floor.
What Happens when Driftwood Sinks to the Bottom of the Ocean?
There are 40 deep sea species known to feed and live on wood. These examples picture wood from shipwrecks.
When a piece of driftwood reaches the ocean floor, it is known as a wood fall. A wood fall can support a community of more than 40 different species. Bacteria, crustaceans, worms, and others will slowly consume the wood fall until there is nothing left. It is an important source of food in a place where nutrients are very rare.
This is where the driftwood ends its journey. Next time you see a piece of driftwood in the water, you can think of all of the amazing plants and animals it supports wherever it goes!
Algae – A microscopic organism that makes its own food using the energy from sunlight
Beach – A part of the coastline that is sandy
Coastline – Where the land meets the ocean
Crustaceans – Some aquatic animals with a hard outer covering, like shrimp and crabs
Decomposer – An organism that breaks down dead material into nutrients
Driftwood – Wood that has fallen into the water
Filter Feeder – An organism that filters out nutrients from the surrounding water
Food-Chain – A representation of which animals in an ecosystem eat other animals
Logjam – Driftwood tangled in large groups, often blocking a river’s path
Nutrients – Substances that nourish a living organism
Organic Matter – Matter that was recently part of a living organism and contains nutrients
Pacific Northwest – An area that includes Oregon, Washington State, and British Columbia
Predator – An animal that hunts and eats other animals
Prey – An animal that is hunted and eaten by other animals
Reef – A large structure in the sea that attracts and sustains a large number of species
Wetland – An area where the ground is very wet and may be covered by standing water
Wood Fall – Driftwood that has sunk to the bottom of the ocean
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