Bythotrephes cederstroemi
Encyclopedia
Bythotrephes longimanus (also Bythotrephes cederstroemi), or the spiny water flea, is a planktonic crustacean
less than 15 millimetre (0.590551181102362 in) long. It is native to fresh waters of Northern Europe
and Asia, but has been accidentally introduced and widely distributed in the Great Lakes area of North America since the 1980s. Bythotrephes is typified by a long abdominal spine with several barbs which protect it from predators.
The spiny water flea is similar to another introduced cladoceran of the same family, the fishhook waterflea Cercopagis pengoi, which however has a more slender spine featuring a prominent loop-like hook at its end (see figure). There is also variation in the shape of the more robust spine of Bythotrephes itself. Specimens arising from sexually produced eggs have a completely straight and relatively shorter spine. In parthenogenetically
produced animals the spine features a kink in the middle (figure). Previously, the kinked-spined animals were thought to be a separate species Bythotrephes cederstroemi.
including Daphnia
and smaller crustaceans. Bythotrephes can consume 10–20 prey organisms a day. It may also eat other small organisms it comes across.
as well as sexual reproduction.
and Asia
, and some parts of central Europe. However the water flea has spread in recent years to many areas throughout Europe including some ports and inland lakes outside its natural range.
In 1984 the crustacean was found in Lake Huron
and soon spread to the other Great Lakes
and some inland lakes within the Midwest, including over 60 inland lakes in Ontario
. It is thought to have been introduced by untreated ballast water from international ships. Concern has increased to the impact of this invasive species
in the Great lakes region and other areas it might have been accidentally introduced. The spiny water flea, eggs and larvae may be caught up in fishing line, downriggers, fishing nets, and other fishing equipment which has caused the spread of the water flea to inland lakes and rivers.
and perch
for prey. These smaller fish are not able to feed on the spiny water flea itself because of the barbs the flea possesses. The spiny water flea's diet consists mostly of Daphnia zooplankton, leading to competition with small and baby fish, and also with native water flea species. Daphnia zooplankton populations have declined in recent years though there is no conclusive evidence as to the cause.
The spiny water flea, is causing serious concerns in the lakes of Canada. The problem is that it feeds on zooplankton
and can actually eliminate zooplankton species. As zooplankton is the backbone of aquatic food chains, this tiny crustacean presents a serious risk to the ecosystem. The eggs survive even after being dried out or eaten by fish.
Invasion by the spiny water flea has also correlated with ecological changes in the Great Lakes
. Since the species' introduction to the Great Lakes in the mid-1980s there has been a decrease in species richness
, as well as decreases in the late summer densities of several other Cladocera species, including Daphnia pulicaria and Daphnia retrocurva.
Crustacean
Crustaceans form a very large group of arthropods, usually treated as a subphylum, which includes such familiar animals as crabs, lobsters, crayfish, shrimp, krill and barnacles. The 50,000 described species range in size from Stygotantulus stocki at , to the Japanese spider crab with a leg span...
less than 15 millimetre (0.590551181102362 in) long. It is native to fresh waters of Northern Europe
Northern Europe
Northern Europe is the northern part or region of Europe. Northern Europe typically refers to the seven countries in the northern part of the European subcontinent which includes Denmark, Estonia, Latvia, Lithuania, Norway, Finland and Sweden...
and Asia, but has been accidentally introduced and widely distributed in the Great Lakes area of North America since the 1980s. Bythotrephes is typified by a long abdominal spine with several barbs which protect it from predators.
Description and taxonomy
Bythotrephes longimanus is a cladoceran crustacean (water flea) recognizable with its straight tail spine averaging about 70% of its length. Adult individuals have three to four barbs on the spine while juveniles have only one pair. The animal has one large eye that is usually black or red. It also possesses a pair of swimming antennae and four pairs of legs, of which the first pair is used to catch prey. Mandibles are used for consumption of prey.The spiny water flea is similar to another introduced cladoceran of the same family, the fishhook waterflea Cercopagis pengoi, which however has a more slender spine featuring a prominent loop-like hook at its end (see figure). There is also variation in the shape of the more robust spine of Bythotrephes itself. Specimens arising from sexually produced eggs have a completely straight and relatively shorter spine. In parthenogenetically
Parthenogenesis
Parthenogenesis is a form of asexual reproduction found in females, where growth and development of embryos occur without fertilization by a male...
produced animals the spine features a kink in the middle (figure). Previously, the kinked-spined animals were thought to be a separate species Bythotrephes cederstroemi.
Diet
The spiny water flea preys on smaller planktonic organisms. Its diet consists mostly of zooplanktonZooplankton
Zooplankton are heterotrophic plankton. Plankton are organisms drifting in oceans, seas, and bodies of fresh water. The word "zooplankton" is derived from the Greek zoon , meaning "animal", and , meaning "wanderer" or "drifter"...
including Daphnia
Daphnia
Daphnia are small, planktonic crustaceans, between 0.2 and 5 mm in length. Daphnia are members of the order Cladocera, and are one of the several small aquatic crustaceans commonly called water fleas because of their saltatory swimming style...
and smaller crustaceans. Bythotrephes can consume 10–20 prey organisms a day. It may also eat other small organisms it comes across.
Reproduction
The spiny water flea can reproduce quickly with upwards of ten offspring every two weeks. Since the crustacean is only active from late spring to fall, eggs may lie dormant for the winter and hatch when the body of water has warmed up. The eggs are resilient to weather conditions allowing the eggs to survive extremely cold conditions. Though the majority of the water flea's population is female, it is capable of asexual reproductionAsexual reproduction
Asexual reproduction is a mode of reproduction by which offspring arise from a single parent, and inherit the genes of that parent only, it is reproduction which does not involve meiosis, ploidy reduction, or fertilization. A more stringent definition is agamogenesis which is reproduction without...
as well as sexual reproduction.
Geographical range
The spiny water flea is native to northern EuropeEurope
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
and Asia
Asia
Asia is the world's largest and most populous continent, located primarily in the eastern and northern hemispheres. It covers 8.7% of the Earth's total surface area and with approximately 3.879 billion people, it hosts 60% of the world's current human population...
, and some parts of central Europe. However the water flea has spread in recent years to many areas throughout Europe including some ports and inland lakes outside its natural range.
In 1984 the crustacean was found in Lake Huron
Lake Huron
Lake Huron is one of the five Great Lakes of North America. Hydrologically, it comprises the larger portion of Lake Michigan-Huron. It is bounded on the east by the Canadian province of Ontario and on the west by the state of Michigan in the United States...
and soon spread to the other Great Lakes
Great Lakes
The Great Lakes are a collection of freshwater lakes located in northeastern North America, on the Canada – United States border. Consisting of Lakes Superior, Michigan, Huron, Erie, and Ontario, they form the largest group of freshwater lakes on Earth by total surface, coming in second by volume...
and some inland lakes within the Midwest, including over 60 inland lakes in Ontario
Ontario
Ontario is a province of Canada, located in east-central Canada. It is Canada's most populous province and second largest in total area. It is home to the nation's most populous city, Toronto, and the nation's capital, Ottawa....
. It is thought to have been introduced by untreated ballast water from international ships. Concern has increased to the impact of this invasive species
Invasive species
"Invasive species", or invasive exotics, is a nomenclature term and categorization phrase used for flora and fauna, and for specific restoration-preservation processes in native habitats, with several definitions....
in the Great lakes region and other areas it might have been accidentally introduced. The spiny water flea, eggs and larvae may be caught up in fishing line, downriggers, fishing nets, and other fishing equipment which has caused the spread of the water flea to inland lakes and rivers.
Impact in introduced areas
Bythotrephes competes with several fish including panfishPanfish
A panfish, also spelled pan-fish or pan fish, is an edible game fish that usually doesn't outgrow the size of a frying pan. The term is also commonly used by anglers to refer to any small catch that will fit in a pan, but is large enough to be legal. However its definition and usage varies with...
and perch
Perch
Perch is a common name for fish of the genus Perca, freshwater gamefish belonging to the family Percidae. The perch, of which there are three species in different geographical areas, lend their name to a large order of vertebrates: the Perciformes, from the Greek perke meaning spotted, and the...
for prey. These smaller fish are not able to feed on the spiny water flea itself because of the barbs the flea possesses. The spiny water flea's diet consists mostly of Daphnia zooplankton, leading to competition with small and baby fish, and also with native water flea species. Daphnia zooplankton populations have declined in recent years though there is no conclusive evidence as to the cause.
The spiny water flea, is causing serious concerns in the lakes of Canada. The problem is that it feeds on zooplankton
Zooplankton
Zooplankton are heterotrophic plankton. Plankton are organisms drifting in oceans, seas, and bodies of fresh water. The word "zooplankton" is derived from the Greek zoon , meaning "animal", and , meaning "wanderer" or "drifter"...
and can actually eliminate zooplankton species. As zooplankton is the backbone of aquatic food chains, this tiny crustacean presents a serious risk to the ecosystem. The eggs survive even after being dried out or eaten by fish.
Invasion by the spiny water flea has also correlated with ecological changes in the Great Lakes
Great Lakes
The Great Lakes are a collection of freshwater lakes located in northeastern North America, on the Canada – United States border. Consisting of Lakes Superior, Michigan, Huron, Erie, and Ontario, they form the largest group of freshwater lakes on Earth by total surface, coming in second by volume...
. Since the species' introduction to the Great Lakes in the mid-1980s there has been a decrease in species richness
Species richness
Species richness is the number of different species in a given area. It is represented in equation form as S.Species richness is the fundamental unit in which to assess the homogeneity of an environment. Typically, species richness is used in conservation studies to determine the sensitivity of...
, as well as decreases in the late summer densities of several other Cladocera species, including Daphnia pulicaria and Daphnia retrocurva.
External links
- Life history and effects on the great lakes of the spiny tailed Bythotrephes
- Bythotrephes longimanus, Invading Species
- GLANSIS Species FactSheet
- Species Profile- Spiny Water Flea (Bythotrephes longimanus), National Invasive Species Information Center, United States National Agricultural LibraryUnited States National Agricultural LibraryThe United States National Agricultural Library is one of the world's largest agricultural research libraries, and serves as a National Library of the United States and as the library of the United States Department of Agriculture...
. Lists general information and resources for Spiny Water Flea.