Orlången is a lake

Lake

A lake is a body of relatively still fresh or salt water of considerable size, localized in a basin, that is surrounded by land. Lakes are inland and not part of the ocean and therefore are distinct from lagoons, and are larger and deeper than ponds. Lakes can be contrasted with rivers or streams,...

 in central Huddinge Municipality

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....

, just south 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...

, 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....

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Orlången, one of the lakes in the Tyresån Lake System

Tyresån Lake System

Tyresån Lake System is a number of lakes in Sweden with a common basin of 251.5 km2....

, forms part of the Orlången Nature Reserve

Orlången Nature Reserve

Orlången Nature Reserve is a nature reserve surrounding Lake Orlången in central Huddinge Municipality, south of Stockholm, Sweden.There are four lakes within the reserve: Trehörningen , Ågestasjön, Orlången, and Mörtsjön....

.

Catchment area

The catchment area is composed of criss-crossing fractured valleys with alternating agricultural lands and forests. The lake and its shores are highly popular for open-air activities such as fishing, bathing, birdwatching, tour skating

Tour skating

Tour skating is a sport and recreational form oflong distance ice skating on natural ice.The Nordic style of tour skating is popular in the Nordic countries,especially Sweden, but increasingly in...

, canoeing, skiing, and walking. The Bottnen ("The Bottom") wetland near the inflow from Mörtsjön is an important bird locale. There are several public baths by the lake, but its many cliffs are also popular spots to spend a summer day. Approximately half of the lake is available for angling for people with the required angling card.

Environmental impact

Though the mud-filled valleys surrounding Orlången originally made it moderately eutrophic

Eutrophication

Eutrophication or more precisely hypertrophication, is the movement of a body of water′s trophic status in the direction of increasing plant biomass, by the addition of artificial or natural substances, such as nitrates and phosphates, through fertilizers or sewage, to an aquatic system...

, extended accumulation of nutrients from neighbouring populated areas has made it highly eutrophic. The deepest areas of the lake are depleted of oxygen during both winters and summers, which can indicate that internal loads are worsening the situation; the lake is possibly self-fertilising, as nutrients are released from its sediments. The present discharge of 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...

, mostly deriving from three residential areas by the lake, is still too high although it remains controllable.

Flora and fauna

Aquatic plants includes 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...

, Club-rush, Wood Club-rush, Broadleaf Cattail

Typha latifolia

Typha latifolia is a perennial herbaceous plant in the genus Typha. It is found as a native plant species in North and South America, Europe, Eurasia, and Africa...

, Flowering Rush, Water Hemlock

Cicuta virosa

Cicuta virosa is a species of Cicuta, native to northern and central Europe, northern Asia and northwestern North America. It is a perennial herbaceous plant which grows up to 1–2 m tall. The stems are smooth, branching, swollen at the base, purple-striped, and hollow except for partitions at the...

, 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...

, Yellow Loosestrife

Lysimachia vulgaris

Lysimachia vulgaris is a species of herbaceous perennial plants in the genus Lysimachia native to wetlands, damp meadows and forests of Eurasia. It is a 50-150 cm tall plant with an upright habit, blooming from June through August with erect panicles of conspicuous yellow flowers. L...

, Bittersweet

Solanum dulcamara

Solanum dulcamara, also known as bittersweet, bittersweet nightshade, bitter nightshade, blue bindweed, Amara Dulcis, climbing nightshade, fellenwort, felonwood, poisonberry, poisonflower, scarlet berry, snakeberry, trailing bittersweet, trailing nightshade, violet bloom, or woody...

, Yellow Water-lily

Nuphar lutea

Nuphar lutea is an aquatic plant of the family Nymphaeaceae, native to temperate regions of Europe, northwest Africa, and western Asia.-Growth:...

, White Water-lily

Nymphaea alba

Nymphaea alba, also known as the European White Waterlily, White Lotus, or Nenuphar, is an aquatic flowering plant of the family Nymphaeaceae....

, Broad-leaved Pondweed

Potamogeton natans

Potamogeton natans L. is an aquatic species in the genus Potamogeton native to quiet or slow-flowing freshwater habitats throughout the Holarctic Kingdom....

, Red Pondweed

Potamogeton alpinus

Potamogeton alpinus is a species of aquatic plant known by the common names alpine pondweed and red pondweed. It is native to much of the Northern Hemisphere, including Eurasia, Greenland, Canada, and northern parts of the United States. It grows in water bodies such as ponds, lakes, marshes, and...

, Whorled Water-milfoil, Amphibious Bistort

Persicaria amphibia

Persicaria amphibia is a species of flowering plant in the knotweed family known by several common names, including water knotweed, water smartweed, and amphibious bistort. It is native to much of North America and Eurasia, but it is known on most continents as an introduced species and sometimes...

, Water-soldier

Stratiotes aloides

-Origins:found in Europe and NW AsiaIn Britain it was once common in East Anglia and still is in many places, particularly wet ditches and healthy ponds.-Description:A rosette of serrated leaves.White flowers are produced in the Summer....

, Frogbit

Hydrocharis morsus-ranae

Hydrocharis morsus-ranae, Frogbit, is a flowering plant belonging to the genus Hydrocharis in the family Hydrocharitaceae. In North America, it is referred to as Common Frogbit or European Frogbit to distinguish it from the related American Frogbit .It is a small floating plant resembling a small...

, Duckweed

Lemna minor

Lemna minor is a species of Lemna with a subcosmopolitan distribution, native throughout most of Africa, Asia, Europe and North America, occurring everywhere that freshwater ponds and slow-moving streams occur, except for arctic and subarctic climates...

, Greater Bladderwort

Utricularia vulgaris

Utricularia vulgaris is an aquatic species of bladderwort found in Asia and Europe. The plant is a free-floating and does not put down roots. Stems can attain lengths of over one metre in a single growing season, but die back and form turions in winter...

, and Greater Duckweed. Along the shores of the lake are Hybrid Crack Willow, Alder, Bay Willow, Grey Willow, 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...

, Ash, Purple-loosestrife, Marsh Fern

Thelypteris palustris

Thelypteris palustris, or the marsh fern, is a fern native to eastern North America and across Eurasia. It prefers to grow in marshy situations in full sun.-References:*...

, Wild Angelica, Marsh Woundwort

Stachys palustris

Stachys palustris, commonly known as Marsh Woundwort or Marsh Hedgenettle, is an edible perennial grassland herb growing to 80 centimeters tall. It is native to parts of Eurasia.-External links:**...

, Gypsywort, Creeping Spearwort, Marsh Cinquefoil

Potentilla palustris

Comarum palustre , known by the common names Purple Marshlocks, Swamp Cinquefoil and Marsh Cinquefoil, is a common waterside shrub. It has a Circumboreal distribution, occurring throughout North America, Europe, and Asia, particularly the northern regions...

, Marsh-marigold

Caltha palustris

Caltha palustris is a herbaceous perennial plant of the buttercup family, native to marshes, fens, ditches and wet woodland in temperate regions of the Northern Hemisphere....

, Bittersweet

Solanum dulcamara

Solanum dulcamara, also known as bittersweet, bittersweet nightshade, bitter nightshade, blue bindweed, Amara Dulcis, climbing nightshade, fellenwort, felonwood, poisonberry, poisonflower, scarlet berry, snakeberry, trailing bittersweet, trailing nightshade, violet bloom, or woody...

, Skullcap, Corn Mint

Mentha arvensis

Mentha arvensis is a species of mint with a circumboreal distribution. It is native to the temperate regions of Europe and western and central Asia, east to the Himalaya and eastern Siberia, and North America.It is a herbaceous perennial plant growing to 10–60 cm tall...

, Meadowsweet, Trifid Bur-marigold

Bidens tripartita

Bidens tripartita, commonly known as Three-lobe Beggarticks, Three-part Beggarticks, Leafy-bracted Beggarticks or Trifid Bur-marigold, is a flowering plant in the genus Bidens. It is native to large parts of the Northern hemisphere, including Europe, the Indian subcontinent, North America,...

, and Purple Small-reed

Calamagrostis canescens

Calamagrostis canescens Roth is a species of grass in the Poaceae family, native to Europe and western Siberia....

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An inventory of dragonflies

Dragonfly

A dragonfly is a winged insect belonging to the order Odonata, the suborder Epiprocta or, in the strict sense, the infraorder Anisoptera . It is characterized by large multifaceted eyes, two pairs of strong transparent wings, and an elongated body...

 in the north-eastern end of the lake documented a presence of Red-eyed Damselfly, Northern Damselfly

Coenagrion hastulatum

The Northern Damselfly or Spearhead Bluet is a damselfly in the family Coenagrionidae.The species is widespread and common in northern Eurasia but is restricted to elevated or bog-like sites towards the west and south. In Britain, it is confined to a few small lochans in Scotland.C...

, Azure Damselfly, Brown Hawker, Club-tailed Dragonfly

Gomphus vulgatissimus

The Common Club-tail is a medium sized species of dragonfly in the family Gomphidae. It is found in most of Europe and is present now in the south of France. Its natural habitat are clean, streaming rivers and creeks with sandy soil. It can be seen from mid-April in the south to August. Once they...

, Downy Emerald, and Four-spotted Chaser.

Fishes present in the lake includes Smelt

Osmerus

Osmerus is a genus of fish in the Osmeridae family.It contains the following species:* Pygmy smelt * Rainbow smelt * European smelt...

, Pike

Northern Pike

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

, 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:...

, 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...

, 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:...

, 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....

, 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...

, 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...

, 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,...

, 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...

, and Ruffe

Ruffe

The Eurasian Ruffe or simply Ruffe is a freshwater fish found in temperate regions of Europe and northern Asia. It has been introduced into the Great Lakes of North America, reportedly with unfortunate results...

. 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...

 was introduced in the 1970s.

Common birds include 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...

, Canada Goose

Canada Goose

The Canada Goose is a wild goose belonging to the genus Branta, which is native to arctic and temperate regions of North America, having a black head and neck, white patches on the face, and a brownish-gray body....

, 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:...

, Water Rail

Water Rail

The Water Rail is a bird of the rail family which breeds in well-vegetated wetlands across Europe, Asia and North Africa. Northern and eastern populations are migratory, but this species is a permanent resident in the warmer parts of its breeding range...

, 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...

, Marsh Harrier

Marsh harrier

The marsh harriers are birds of prey of the harrier subfamily. They are medium-sized raptors and the largest and broadest-winged harriers. Most of them are associated with marshland and dense reedbeds...

, Northern Lapwing

Northern Lapwing

The Northern Lapwing , also known as the Peewit, Green Plover or just Lapwing, is a bird in the plover family. It is common through temperate Eurasia....

, 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...

, Tern

Common Tern

The Common Tern is a seabird of the tern family Sternidae. This bird has a circumpolar distribution, breeding in temperate and sub-Arctic regions of Europe, Asia and east and central North America. It is strongly migratory, wintering in coastal tropical and subtropical regions. It is sometimes...

, 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...

, 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...

, 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 ....

, Reed Warbler

Reed Warbler

The Eurasian Reed Warbler, or just Reed Warbler, Acrocephalus scirpaceus, is an Old World warbler in the genus Acrocephalus. It breeds across Europe into temperate western Asia. It is migratory, wintering in sub-Saharan Africa....

, Sedge Warbler

Sedge Warbler

The Sedge Warbler is an Old World warbler in the genus Acrocephalus. It is a medium-sized warbler with a brown, streaked back and wings and a distinct pale supercilium. Sedge Warblers are migratory, crossing the Sahara to get from their European and Asian breeding grounds to spend winter in Africa...

, Marsh Warbler

Marsh Warbler

The Marsh Warbler, Acrocephalus palustris, is an Old World warbler currently classified in the family Acrocephalidae. It breeds in temperate Europe and western Asia and winters mainly in south east Africa...

, and 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...

. Additionally, a couple of Cranes

Common Crane

The Common Crane , also known as the Eurasian Crane, is a bird of the family Gruidae, the cranes.It is a large, stately bird and a medium-sized crane at 100–130 cm long, with a 180–240 cm wingspan and a weight of 4.5–6 kg...

 has been breeding by the lake for about ten years.

The deciduous

Deciduous

Deciduous means "falling off at maturity" or "tending to fall off", and is typically used in reference to trees or shrubs that lose their leaves seasonally, and to the shedding of other plant structures such as petals after flowering or fruit when ripe...

 forest north of the lake and the shallow reeds there is an important biotope

Biotope

Biotope is an area of uniform environmental conditions providing a living place for a specific assemblage of plants and animals. Biotope is almost synonymous with the term habitat, but while the subject of a habitat is a species or a population, the subject of a biotope is a biological community.It...

 for bat

Bat

Bats are mammals of the order Chiroptera "hand" and pteron "wing") whose forelimbs form webbed wings, making them the only mammals naturally capable of true and sustained flight. By contrast, other mammals said to fly, such as flying squirrels, gliding possums, and colugos, glide rather than fly,...

s, as the area produces a plenitude of insects while offering favourable milieux for hibernation. Inventories during the 1990s have documented a presence of 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...

, Parti-coloured Bat

Parti-coloured bat

The Parti-coloured Bat or Rearmouse is a species of bats in the family of Vesper bats. It is a medium sized bat.- Description :...

, 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....

, Noctule

Common Noctule

The Common Noctule is a species of bat common throughout Europe, Asia, and North Africa. The UK distribution can be found on the National Biodiversity Network website ....

, Soprano Pipistrelle

Soprano Pipistrelle

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

, Brown Long-eared Bat

Brown long-eared bat

The brown long-eared bat or common long-eared bat is a fairly large European bat. It has distinctive ears, long and with a distinctive fold...

, Whiskered Bat

Whiskered bat

The whiskered bats Myotis mystacinus and related species, are small European bats with long fur. Although uncommon, M. mystacinus is often found around human habitation and around water; it is similar to Brandt's bat Myotis brandtii, from which it was distinguished as a separate species only in...

.