Vårbyfjärden is a strait

Strait

A strait or straits is a narrow, typically navigable channel of water that connects two larger, navigable bodies of water. It most commonly refers to a channel of water that lies between two land masses, but it may also refer to a navigable channel through a body of water that is otherwise not...

 in south-eastern Lake Mälaren

Mälaren

Lake Mälaren is the third-largest lake in Sweden, after Lakes Vänern and Vättern. Its area is 1,140 km² and its greatest depth is 64 m. Mälaren spans 120 kilometers from east to west...

 south-west of Stockholm

Stockholm

Stockholm is the capital and the largest city of Sweden and constitutes the most populated urban area in Scandinavia. Stockholm is the most populous city in Sweden, with a population of 851,155 in the municipality , 1.37 million in the urban area , and around 2.1 million in the metropolitan area...

 in Sweden

Sweden

Sweden , officially the Kingdom of Sweden , is a Nordic country on the Scandinavian Peninsula in Northern Europe. Sweden borders with Norway and Finland and is connected to Denmark by a bridge-tunnel across the Öresund....

.

Vårbyfjärden separates Ekerö

Ekerö

Ekerö is a locality and the seat of Ekerö Municipality in Stockholm County, Sweden, with 10,322 inhabitants in 2005.Agnetha Fältskog of ABBA fame lives on the island ....

 island and Ekerö Municipality

Ekerö Municipality

Ekerö Municipality is a municipality in Stockholm County in east central Sweden. The name comes from the island Ekerö, and literally means "Oak Island". Its seat is located in the town of Ekerö....

 north of it, from Södertälje

Södertälje Municipality

Södertälje Municipality is a municipality in Stockholm County in east central Sweden. Its seat is located in the city of Södertälje....

 and Huddinge Municipalities

Huddinge Municipality

Huddinge Municipality is a municipality in Stockholm County in east central Sweden. Its seat is located in Huddinge, which is a part of Stockholm urban area.The municipality is the second most populated in Stockholm County....

 south of it and Stockholm Municipality

Stockholm Municipality

Stockholm Municipality or the City of Stockholm is a municipality in Stockholm County in east central Sweden. It is the largest of the 290 municipalities of the country in terms of population, but one of the smaller in terms of area, making it the most densely populated...

 on its western side. South of Vårbyfjärden is Albysjön,

History

Of the three islands in the bay, Estbröte, appears in the Chronicle of Eric

Eric Chronicles

Eric's Chronicle is the oldest surviving Swedish chronicle. It was written by an unknown author between about 1320 and 1335....

. In 1206, the wife of the legendary Jarl Jon Jarl

Jon Jarl

Jon Jarl was a legendary Swedish jarl at the end of the 12th and in the early 13th centuries. He is mentioned in Eric's Chronicle from the 1320s to have spent years fighting against Russians and Ingrians in the early Swedish-Novgorodian Wars...

 caught a band of Estonia

Estonia

Estonia , officially the Republic of Estonia , is a state in the Baltic region of Northern Europe. It is bordered to the north by the Gulf of Finland, to the west by the Baltic Sea, to the south by Latvia , and to the east by Lake Peipsi and the Russian Federation . Across the Baltic Sea lies...

n pirates on the island and had them all executed as a revenge for her husband's death.

The eastern shore is known to have been inhabited since pre-historic times, when beacon

Beacon

A beacon is an intentionally conspicuous device designed to attract attention to a specific location.Beacons can also be combined with semaphoric or other indicators to provide important information, such as the status of an airport, by the colour and rotational pattern of its airport beacon, or of...

s there were ignited to warn when hostile ships approached. A man who guarded the strait was called a vörðr, which gave the bay and various locations surrounding it their names. A treasure from the 10th century found there contained Arabian coins and jewels, so apparently the bay was important for navigation. The mansion of Vårby gård was built in the 18th century and encompassed most of the area west of the bay. All the mansion's buildings, including greenhouses with exotic trees and bushes, have been demolished, but parts of the gardens are still used for allotment gardens

Allotment (gardening)

An allotment garden, often called simply an allotment, is a plot of land made available for individual, non-professional gardening. Such plots are formed by subdividing a piece of land into a few or up to several hundreds of land parcels that are assigned to individuals or families...

.

Catchment area

Vårbyfjärden, which is surrounded by several suburbs such as Botkyrka, Skärholmen, and Vårby gård, is an important recreational area for thousands of people. Fishing, sailing, canoeing, and bathing are popular activities during summers. There is a marina at Slagsta where ferries offers trips across the bay.

Environmental impact

Water quality is good as the strait is located downstream from Södra Björkfjärden, one of the largest and cleanest bodies of water in Lake Mälaren. The marina at Slagsta contributes some oil and paint spills. Closer to Stockholm stormwater

Stormwater

Stormwater is water that originates during precipitation events. It may also be used to apply to water that originates with snowmelt that enters the stormwater system...

 discharge causes increased levels of chloride

Chloride

The chloride ion is formed when the element chlorine, a halogen, picks up one electron to form an anion Cl−. The salts of hydrochloric acid HCl contain chloride ions and can also be called chlorides. The chloride ion, and its salts such as sodium chloride, are very soluble in water...

 and phosphorus

Phosphorus

Phosphorus is the chemical element that has the symbol P and atomic number 15. A multivalent nonmetal of the nitrogen group, phosphorus as a mineral is almost always present in its maximally oxidized state, as inorganic phosphate rocks...

.

Flora and fauna

Vascular plants present include Reed

Phragmites

Phragmites, the Common reed, is a large perennial grass found in wetlands throughout temperate and tropical regions of the world. Phragmites australis is sometimes regarded as the sole species of the genus Phragmites, though some botanists divide Phragmites australis into three or four species...

,
Common Club-rush,
Cattail, Scottish Dock,
Flowering Rush, Yellow Iris

Iris pseudacorus

Iris pseudacorus is a species of Iris, native to Europe, western Asia and northwest Africa. Common names include yellow iris and yellow flag...

,
Water Plantain, Shoreweed,
Spring Quillwort,
Quillwort

Quillwort

Isoëtes, also written Isoetes and commonly known as the quillworts, is a genus of plants in the class Isoetopsida and order Isoetales. They are considered "fern allies". There are about 140-150 species, with a cosmopolitan distribution but often scarce to rare...

, Eight-stamened Waterwort,
Needle Spike-rush

Eleocharis acicularis

Eleocharis acicularis is a species of spikesedge known by the common names needle spikerush and dwarf hairgrass. It has a circumboreal distribution and it can also be found throughout the rest of the Americas. It is also found in Australia, where it is probably an introduced species...

,
Amphibious Bistort,
Arrowhead

Sagittaria sagittifolia

Sagittaria sagittifolia is a flowering plant in the family Alismataceae, native to wetlands throughout the temperate regions of Europe and Asia; in Britain it is the only native Sagittaria....

,
Perfoliate Pondweed,
Fennel Pondweed,
Lesser Pondweed,
Various-leaved Pondweed,
Grass-wrack Pondweed,
Rigid Hornswort

Ceratophyllum demersum

Ceratophyllum demersum is a species of Ceratophyllum. It is a submerged, free-floating aquatic plant, native to North America but nowadays having a cosmopolitan distribution in temperate and tropical regions...

,
Horned Pondweed,
Nuttail's Waterweed

Elodea nuttallii

Elodea nuttallii is a species of waterweed known by the common name western waterweed. This is a perennial aquatic plant which is native to North America where it grows submersed in lakes, rivers, and other shallow water bodies. It is also found in Eurasia, where it is commonly weedy; it is not...

,
Alternate Water-milfoil,
Spiked Water-milfoil

Myriophyllum spicatum

Myriophyllum spicatum is a species of Myriophyllum native to Europe, Asia, and north Africa. It is a submerged aquatic plant, and grows in still or slow-moving water.-Description:...

, and
Autumnal Water-starwort.

Along the shores grow trees such as Ash, Elm

Elm

Elms are deciduous and semi-deciduous trees comprising the genus Ulmus in the plant family Ulmaceae. The dozens of species are found in temperate and tropical-montane regions of North America and Eurasia, ranging southward into Indonesia. Elms are components of many kinds of natural forests...

, Hybrid Crack Willow, Oak

Oak

An oak is a tree or shrub in the genus Quercus , of which about 600 species exist. "Oak" may also appear in the names of species in related genera, notably Lithocarpus...

, Aspen

Populus tremula

Populus tremula, commonly called aspen, common aspen, Eurasian aspen, European aspen, trembling poplar, or quaking aspen, is a species of poplar native to cool temperate regions of Europe and Asia, from the British Isles east to Kamchatka, north to inside the Arctic Circle in Scandinavia and...

, Bird Cherry

Bird Cherry

Prunus padus, known as Bird Cherry or Hackberry, is a species of cherry, native to northern Europe and northern Asia. It is a deciduous small tree or large shrub, 8–16 m tall, which grows north of the Arctic Circle in Norway, Sweden, Finland and Russia...

, Black Alder, Bay Willow, Grey Willow, and Goat Willow.

There are 33 naturally occurring fish species in Vårbysfjärden, making it the richest in fish species in Sweden. Common species include Northern pike

Northern Pike

The northern pike , is a species of carnivorous fish of the genus Esox...

, Perch

European perch

The European perch, Perca fluviatilis, is a predatory species of perch found in Europe and Asia. In some areas it is known as the redfin perch or English perch, and it is often known simply as perch. The species is a popular quarry for anglers and has been widely introduced beyond its native area,...

, Roach

Rutilus

Rutilus is a genus of fishes in the family Cyprinidae, commonly called roaches. Locally, the name "roach" without any further qualifiers is also used for particular species, particularly the Common Roach Rutilus (Latin for "shining, red, golden, auburn") is a genus of fishes in the family...

, Rudd

Rudd

The common rudd Scardinius erythropthalmus is a bentho-pelagic freshwater fish, widely spread in Europe and middle Asia, around the basins of the North, Baltic, Black, Caspian and Aral seas.-Artificially introduced:...

, Silver Bream

Silver Bream

The Silver Bream is a species of ray-finned fish in the Cyprinidae family.-Locations:It is found in Albania, Andorra, Armenia, Austria, Azerbaijan, Belarus, Belgium, Bulgaria, Cyprus, Czech Republic, Estonia, Faroe Islands, Finland, France, Georgia, Germany, Gibraltar, Hungary, Iceland, Iran,...

, Carp bream

Carp bream

The common bream, freshwater bream, bream, bronze bream or carp bream, Abramis brama, is a European species of freshwater fish in the family Cyprinidae....

, Bleak

Bleak

The common bleak is a small pelagic fish of the Cyprinid family. It is often referred to simply as a "bleak", though this term can refer to any species of Alburnus.-Description:...

, European smelt

European smelt

The Smelt or European smelt is a species of fish in the Osmeridae family.- Shape and appearance :The body of the European smelt is typically 15 to 18 cm long, slender and slightly flattened on either side. Larger fish may reach 30 cm in length. Smelts have a slightly translucent body...

, Zander

Zander

Zander is a species of fish. The scientific name is Sander lucioperca , and it is closely allied to perch. Zander are often called pike-perch as they resemble the pike with their elongated body and head, and the perch with their spiny dorsal fin. Zander are not, as is commonly believed, a pike and...

, Burbot

Burbot

The burbot is the only gadiform fish inhabiting freshwaters. It is also known as mariah, the lawyer, and eelpout. It is closely related to the marine common ling and the cusk...

, Tench

Tench

The tench or doctor fish is a freshwater and brackish water fish of the cyprinid family found throughout Eurasia from Western Europe including the British Isles east into Asia as far as the Ob and Yenisei Rivers. It is also found in Lake Baikal...

, and Crucian carp

Crucian carp

The crucian carp is a member of the family Cyprinidae, which includes many other fish, such as the common carp, or the smaller minnows. They inhabit lakes, ponds, and slow-moving rivers throughout Europe and Asia. The crucian is a medium-sized cyprinid, which rarely exceeds a weight of over 3.3...

. Additionally, there a range of introduced species such as Lake trout

Lake trout

Lake trout is a freshwater char living mainly in lakes in northern North America. Other names for it include mackinaw, lake char , touladi, togue, and grey trout. In Lake Superior, they can also be variously known as siscowet, paperbellies and leans...

, Char

Salvelinus

Salvelinus is a genus of salmonid fish often called char or charr; some species are called "trout". Salvelinus is a member of the Salmoninae subfamily of the Salmonidae family. Charr may be identified by light cream pink or red spots over a darker body. Scales tend to be small, with 115-200 along...

, Salmon

Salmon

Salmon is the common name for several species of fish in the family Salmonidae. Several other fish in the same family are called trout; the difference is often said to be that salmon migrate and trout are resident, but this distinction does not strictly hold true...

, and Spined loach

Spined Loach

The Spined Loach is a common freshwater fish in Europe and Asia. It is sometimes known as spotted weather loach, not to be confused with the "typical" weather loaches of the genus Misgurnus...

. The presence of Fourhorn sculpin

Fourhorn sculpin

The fourhorn sculpin is a species of fish in the Cottidae family. It is a demersal fish distributed mainly in brackish arctic coastal waters in Canada, Greenland, Russia, and Alaska, and also as a relict in the boreal Baltic Sea...

s is a reminder from the time when lake Mälaren was a still bay forming part of the Baltic Sea

Baltic Sea

The Baltic Sea is a brackish mediterranean sea located in Northern Europe, from 53°N to 66°N latitude and from 20°E to 26°E longitude. It is bounded by the Scandinavian Peninsula, the mainland of Europe, and the Danish islands. It drains into the Kattegat by way of the Øresund, the Great Belt and...

.

Vårbyfjärden was one of the first maritime environments in Sweden to suffer Crayfish plague

Crayfish plague

Crayfish plague, Aphanomyces astaci, is a water mould that infects crayfish, most notably the European Astacus which dies within a few weeks of being infected...

  which hit the lake in 1907. The plague was introduced in Lake Mälaren by affected animals thrown into the water at Kornhamnstorg

Kornhamnstorg

Kornhamnstorg is a public square in Gamla stan, the old town in central Stockholm, Sweden.Old names : Kornhaffn , Jernboen , Åkaretorget , Kornhampns torget...

 in central Stockholm, from where ships carrying Crayfish

Crayfish

Crayfish, crawfish, or crawdads – members of the superfamilies Astacoidea and Parastacoidea – are freshwater crustaceans resembling small lobsters, to which they are related...

es spread the disease further inland. Since then Signal crayfish

Signal crayfish

The signal crayfish, Pacifastacus leniusculus, is a North American species of crayfish. It was introduced to Europe in the 1960s to supplement the Scandinavian Astacus astacus fisheries, which were being damaged by crayfish plague, but the imports turned out to be a carrier of that disease...

 has been introduced.

Common birds include Mallard

Mallard

The Mallard , or Wild Duck , is a dabbling duck which breeds throughout the temperate and subtropical Americas, Europe, Asia, and North Africa, and has been introduced to New Zealand and Australia....

, Coot

Eurasian Coot

The Eurasian Coot, Fulica atra, also known as Coot, is a member of the rail and crake bird family, the Rallidae. The Australian subspecies is known as the Australian Coot.-Distribution:...

, Goldeneye

Common Goldeneye

The Common Goldeneye is a medium-sized sea duck of the genus Bucephala, the goldeneyes. Their closest relative is the similar Barrow's Goldeneye....

, Merganser

Common Merganser

The Common Merganser or Goosander Mergus merganser is a large duck, of rivers and lakes of forested areas of Europe, northern and central Asia, and North America. It eats fish and nests in holes in trees...

, Common Gull

Common Gull

The Common Gull or Mew Gull Larus canus is a medium-sized gull which breeds in northern Asia, northern Europe and northwestern North America. It migrates further south in winter...

, Black-headed Gull

Black-headed Gull

The Black-headed Gull is a small gull which breeds in much of Europe and Asia, and also in coastal eastern Canada. Most of the population is migratory, wintering further south, but some birds in the milder westernmost areas of Europe are resident...

, Herring Gull, Great Black-backed Gull

Great Black-backed Gull

The Great Black-backed Gull is the largest gull in the world, which breeds on the European and North American coasts and islands of the North Atlantic...

, Lesser Black-backed Gull

Lesser Black-backed Gull

The Lesser Black-backed Gull is a large gull that breeds on the Atlantic coasts of Europe. It is migratory, wintering from the British Isles south to West Africa...

, Great Cormorant

Great Cormorant

The Great Cormorant , known as the Great Black Cormorant across the Northern Hemisphere, the Black Cormorant in Australia and the Black Shag further south in New Zealand, is a widespread member of the cormorant family of seabirds...

, Great Crested Grebe

Great Crested Grebe

The Great Crested Grebe is a member of the grebe family of water birds.- Description :The Great Crested Grebe is long with a wingspan. It is an excellent swimmer and diver, and pursues its fish prey underwater. The adults are unmistakable in summer with head and neck decorations...

, Mute Swan

Mute Swan

The Mute Swan is a species of swan, and thus a member of the duck, goose and swan family Anatidae. It is native to much of Europe and Asia, and the far north of Africa. It is also an introduced species in North America, Australasia and southern Africa. The name 'mute' derives from it being less...

, Common sandpiper

Common Sandpiper

The Common Sandpiper is a small Palearctic wader. This bird and its American sister species, the Spotted Sandpiper , make up the genus Actitis. They are parapatric and replace each other geographically; stray birds of either species may settle down with breeders of the other and hybridize...

, and Grey Heron

Grey Heron

The Grey Heron , is a wading bird of the heron family Ardeidae, native throughout temperate Europe and Asia and also parts of Africa. It is resident in the milder south and west, but many birds retreat in winter from the ice in colder regions...

. Along the shores Long-tailed Tit

Long-tailed Tit

The Long-tailed Tit or Long-tailed Bushtit is a common bird found throughout Europe and Asia. There are several extensive accounts of this species, most notably Cramp and Perrins, 1993; Gaston, 1973; and Harrap and Quinn, 1996...

, Thrush Nightingale

Thrush Nightingale

The Thrush Nightingale, Luscinia luscinia , is a small passerine bird that was formerly classed as a member of the thrush family Turdidae, but is now more generally considered to be an Old World flycatcher, Muscicapidae...

, and Lesser Spotted Woodpecker

Lesser Spotted Woodpecker

The Lesser Spotted Woodpecker is a member of the woodpecker family Picidae. It is assigned to the genus Dendrocopos ....

 are common birds. White-tailed eagle

White-tailed Eagle

The White-tailed Eagle , also known as the Sea Eagle, Erne , or White-tailed Sea-eagle, is a large bird of prey in the family Accipitridae which includes other raptors such as hawks, kites, and harriers...

 and Osprey

Osprey

The Osprey , sometimes known as the sea hawk or fish eagle, is a diurnal, fish-eating bird of prey. It is a large raptor, reaching more than in length and across the wings...

 visits the lake regularly, while some other species are seen less frequently, such as Black-throated diver

Black-throated Diver

The Black-throated Loon is a migratory aquatic bird found in the northern hemisphere. The species is known as an Arctic Loon in North America and the Black-throated Diver in Eurasia, its current name is a compromise proposed by the International Ornithological Committee.-Taxonomy:The...

 and Common Moorhen

Common Moorhen

The Common Moorhen is a bird in the Rallidae family with an almost worldwide distribution. The North and South American Committees of the AOU and the IOC have voted on or before July 2011 to split the American forms into a new species Common Gallinule, however, no other committee has voted to...

Northern Bat

Northern Bat

The Northern Bat is a species of bat. An adult Northern Bat has a body length of 4.9-6.6 cm, a tail of 3.2-5.1 cm, and a wing length of 4.1-5.1 cm. The species is found across Europe and Asia, from England to Hokkaidō and south to northern India.-References: 2006 IUCN Red List of Threatened...

, Daubenton's Bat

Daubenton's bat

Daubenton's Bat, Myotis daubentonii, is a Eurasian bat with quite short ears. It ranges from Britain to Japan and is considered to be increasing its numbers in many areas.The name commemorates the French naturalist Louis-Jean-Marie Daubenton....

, Soprano Pipistrelle

Soprano Pipistrelle

The Soprano Pipistrelle is a small bat that was only formally separated from the Common Pipistrelle Pipistrellus pipistrellus in 1999....

, and Brandt's Bat

Brandt's Bat

Brandt's Bat is a species of vesper bat in the Vespertilionidae family.It is found throughout most of Europe and parts of Asia.It is named for the German zoologist Johann Friedrich von Brandt.-Echolocation:...

 have been observed during guided tours around Vårby Gård. Amphibians include Common Frog

Common Frog

The Common Frog, Rana temporaria also known as the European Common Frog or European Common Brown Frog is found throughout much of Europe as far north as well north of the Arctic Circle in Scandinavia and as far east as the Urals, except for most of Iberia, southern Italy, and the southern Balkans...

 and Toads.