Bio Universe
The place where biodiversity lives
Invasive Species
Silver Carp
Invasive species were brought from one place to another, so they aren't native to where ever they were brought to. invasive species also have negative effects on the ecosystem around them. These two fish are examples of invasive species.
Round Goby
Silver Carp
The silver carp is a beautiful light gray fish. It is one of the many bigger kinds of fish. Silver carp reach an average of 1 meter long and weigh around 100 pounds. They are filter feeders and largely consume phytoplankton, but they will still eat zooplankton and detritus. Because they filter feed, they are difficult to catch on regular fishing hooks.
Because silver carp feed on plankton, they can be used for water quality control, especially when there is noxious blue-green algae (also known as cyanobacteria) around. However, sometimes this may not work. Certain kinds of blue-green algae - note the often toxic Microcystis - can go through the silver carp completely unharmed, and sometimes pick up nutrients in the process. And so in some cases, blue-green algae blooms have ended up getting created by the silver carp. In addition, microcystis has been found to produce more toxins when silver carp are around. This has made silver carp a little dangerous to eat, because even though they have natural defenses to their toxins, they can still be full of algae toxins when they're caught.
An example of the size of a silver carp.
In North America
Silver carp had been imported over to North America back in 1970 to control the growth of algae in aquaculture and municipal water treatment facilities. Unfortunately, they had escaped from captivity shortly after they were imported. This is what considers them as a highly invasive species. They often manage to reach extremely high population densities and can have pretty bad effects on the surrounding environment and native animals.
How they affect us
Silver carp have the tendency to leap over 3 metres out of the water when they get startled. This has caused injuries to people going across the water at high speed and slamming into the leaping fish. For example, in 2003, a jet-skiing woman collided with a silver carp and ended up breaking her nose and a vertebra. She almost drowned. In another example, one of these fish broke the jaw of a teenager that was being pulled on an inner tube. For one last example, a British biologist and angler named Jeremy Wade got hit by a silver carp in the head at the Illinois River while he was filming for the second season of a show called River Monsters.
Round Goby
An example of the round goby's small body.
Round gobies are tiny little fish with a distinct black spot on their first dorsal fin. They can grow as long as 24.6 centimetres, and can weigh up to 2.816 ounces, although their maximum weight increases as they get older. Baby round gobies that haven't even lived one whole year yet are gray. As they get older they get covered in markings that are gray, black, brown, and even olive green. When the males become adults, they turn an inky black during the spawning season, and develop swollen cheeks. You can easily tell a male from a female from the shape and colour of their urogenital papilla. It is white to gray, long, and pointed for the male round gobies, and is brown, short, and blunt-tipped for females.
These fish usually feed nocturnally, but we have seen them come out diurnally. We believe that they can only detect their prey while stationary. The primary diet of the round goby consists of zebra mussels, insect larvae, worms, and mollusks. Adults mainly feed on mollusks.
In North America
Round gobies were accidentally introduced to the North American Great Lakes from ballast water transfer in cargo ships. They were first found in the continent's St. Clair River back in 1990. The consequences do seem quite complex, though, since it competes with the native species but also eats other invasive species. The round goby is an aggressive fish, and it competes (and wins) against species native to the land for food, shelter, and nesting grounds. This causes the native species' numbers to be reduced. They are also predators to eggs of many native species; ones that are quite important to angling industries. The round goby's ability to survive degraded environmental conditions has helped it to increase it's competitive advantage compared to other species.