2009 April | OceanGuy

Are lionfish a threat to Atlantic Ocean fish?

Posted by Ocean Facts on 24 April, 2009

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This item was filled under Animals, Facts, Ocean Life

Lionfish are native to the Indo-Pacific and Red Sea, but are now established along the eastern coast of the U.S. from Florida to North Carolina. They are also regularly found throughout the Bahamas and northern Caribbean, and have been sighted as far south as Nicaragua and as far east as the U.S. Virgin Islands.

How did the fish get to the Atlantic? While the exact cause is unknown, it's likely that humans provided a helping hand. Experts speculate that people have been dumping unwanted lionfish from home aquariums into the Atlantic Ocean for up to 25 years.

Since lionfish are not native to Atlantic waters, they have very few predators. They are also voracious predators that feed on small shrimp and large fish, including the young of important commercial fish species such as snapper and grouper.

Between 2000 and 2003, 49 lionfish sightings were reported at 16 different shipwrecks and natural hard-bottom locations. During a summer 2004 research expedition, NOAA scientists collected 155 lionfish at 19 different locations off the North Carolina coast alone. The jump in numbers and distribution over such a short time, plus sightings of juveniles smaller than those sold for aquaria, indicates that the lionfish is reproducing in the Atlantic Ocean. This marks the first time that a western Pacific fish has populated the waters of the U.S. Atlantic coast.

Unfortunately, NOAA researchers have concluded that invasive lionfish populations will continue to grow and cannot be eliminated using conventional methods. Marine invaders are nearly impossible to eradicate once established.

How lionfish will affect native fish populations and commercial fishing industries has yet to be determined. What is known is that non-native species can dramatically affect native ecosystems and local fishing economies. Experts are carefully studying these invaders to better understand the role their role in, and potential threat to, Atlantic Ocean ecosystems.

If you spot a lionfish, avoid it and report it. These fish have venomous spines that can be very painful. Scientists are also actively studying these fish to better understand the potential threat that lionfish pose to key reef and commercial fish species. Learning more about the habits and preferences of lionfish in non-native waters also helps experts determine where to look for these invasive fish.

For more information
"Responders Capture First Lionfish Invader in Sanctuary," NOS news
"The Lionfish Invasion," NOS Education
Report a Lionfish Sighting
Aquatic Invasive Species
Lionfish Sightings Distribution (U.S. Geological Survey)
Aquatic Nuisance Species Task Force

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What is upwelling?

Posted by Ocean Facts on 24 April, 2009

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This item was filled under Facts, Geology, Oceanography

Winds blowing across the ocean surface push water away. Water then rises up from beneath the surface to replace the water that was pushed away. This process is known as “upwelling.”

Upwelling occurs in the open ocean and along coastlines. The reverse process, called “downwelling,” also occurs when wind causes surface water to build up along a coastline and the surface water eventually sinks toward the bottom.

Water that rises to the surface as a result of upwelling is typically colder and is rich in nutrients. These nutrients “fertilize” surface waters, meaning that these surface waters often have high biological productivity. Therefore, good fishing grounds typically are found where upwelling is common.

For more information:
What Is Upwelling, Pacific Fisheries Environmental Laboratory
Upwelling, NOAA Ocean Explorer
Coastal Currents - Upwelling, NOS Education

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What is marine snow?

Posted by Ocean Facts on 24 April, 2009

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This item was filled under Facts, Ocean Life, Ocean Life (misc.)

As plants and animals near the surface of the ocean die and decay, they fall toward the sea floor, just like leaves and decaying material fall onto a forest floor. In addition to dead animals and plants, marine snow also includes fecal matter, sand, soot, and other inorganic dust.

The decaying material is referred to as “marine snow” because it looks a little bit like white fluffy bits. The “snowflakes” grow as they fall, some reaching several centimeters in diameter. Some flakes fall for weeks before finally reaching the ocean floor.

This continuous rain of marine snow provides food for many deep-sea creatures. Many animals in the dark parts of the ocean filter marine snow from the water or scavenge it from the seabed. Over the past 20 years or so, NOAA scientists and others have measured the amount of useable material in marine snow and found that there is plenty of carbon and nitrogen to feed many of the scavengers in the deep sea.

The small percentage of material not consumed in shallower waters becomes incorporated into the muddy “ooze” blanketing the ocean floor, where it is further decomposed through biological activity. About three-quarters of the deep ocean floor is covered in this thick, smooth ooze. The ooze collects as much as six meters (20 feet) every million years. It is usually 289 meters (948 feet) thick, but can be up to nearly 10 kilometers (6.2 miles) thick.

For more information:
Marine Snow Video, NOAA Ocean Explorer

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