Sicklasjön 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 eastern central 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....

. It is bordering the municipalities of Stockholm

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...

 and Nacka

Nacka Municipality

Nacka Municipality is a municipality in Stockholm County in east central Sweden. Its seat is located at Nacka. The municipality is situated just east of the capital Stockholm and the western parts are considered a suburban part of the Stockholm urban area.The present municipality was created in...

 and is named for the vicinity to the urban district Sickla.

Sicklasjön, historically known as Långsjön ("Long Lake"), is connected to Järlasjön east of it through a narrow strait and to Hammarby Sjö west of it through the canal Sickla Kanal and the sluice

Sluice

A sluice is a water channel that is controlled at its head by a gate . For example, a millrace is a sluice that channels water toward a water mill...

 Sickla Sluss. The lake, forming the northern border of the Nacka Open-air Area (Nacka friluftsområde, colloquially known as Nackareservatet, "Nacka [Nature] Reserve"), is considered as of significant recreational and natural value. Water flow is periodically important but inconsiderable during summers when the lake remains relatively stratified.

Catchment area

The lake is the last lake in the Sicklaån water system formed in an east-west oriented fissure valley. The catchment area is highly exploited with most of it used for one-family houses, block of flats, offices, industrial areas, and roads. On the southern shore are patches of hardwood

Hardwood

Hardwood is wood from angiosperm trees . It may also be used for those trees themselves: these are usually broad-leaved; in temperate and boreal latitudes they are mostly deciduous, but in tropics and subtropics mostly evergreen.Hardwood contrasts with softwood...

 forests, a few feeder streams, a promenade, and the old mansion Lilla Sickla Gård south of which are several minor wetlands. The closed stock pile Hammarbybacken containing various types of excavated materials is located within the catchment area. Next to Sickla Kanal is a subterranean plant used to treat sludge disposal. New residential areas have been constructed in the western end of the lake.

Environmental influence

Approximately 400 kg 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...

 is transported through the lake annually, of which some 80 per cent comes from the other lakes in the water system. Surface runoff

Surface runoff

Surface runoff is the water flow that occurs when soil is infiltrated to full capacity and excess water from rain, meltwater, or other sources flows over the land. This is a major component of the water cycle. Runoff that occurs on surfaces before reaching a channel is also called a nonpoint source...

 adds some 50 kg phosphorus and 600 kg nitrogen

Nitrogen

Nitrogen is a chemical element that has the symbol N, atomic number of 7 and atomic mass 14.00674 u. Elemental nitrogen is a colorless, odorless, tasteless, and mostly inert diatomic gas at standard conditions, constituting 78.08% by volume of Earth's atmosphere...

, while roughly 24 kg phosphorus is released from lake sediments and atmospheric deposits adds some 120 kg of nitrogen. Most of metal contribution, copper

Copper

Copper is a chemical element with the symbol Cu and atomic number 29. It is a ductile metal with very high thermal and electrical conductivity. Pure copper is soft and malleable; an exposed surface has a reddish-orange tarnish...

, lead

Lead

Lead is a main-group element in the carbon group with the symbol Pb and atomic number 82. Lead is a soft, malleable poor metal. It is also counted as one of the heavy metals. Metallic lead has a bluish-white color after being freshly cut, but it soon tarnishes to a dull grayish color when exposed...

, and zinc

Zinc

Zinc , or spelter , is a metallic chemical element; it has the symbol Zn and atomic number 30. It is the first element in group 12 of the periodic table. Zinc is, in some respects, chemically similar to magnesium, because its ion is of similar size and its only common oxidation state is +2...

, comes from Hammarbybacken where high levels of arsenic

Arsenic

Arsenic is a chemical element with the symbol As, atomic number 33 and relative atomic mass 74.92. Arsenic occurs in many minerals, usually in conjunction with sulfur and metals, and also as a pure elemental crystal. It was first documented by Albertus Magnus in 1250.Arsenic is a metalloid...

, chromium

Chromium

Chromium is a chemical element which has the symbol Cr and atomic number 24. It is the first element in Group 6. It is a steely-gray, lustrous, hard metal that takes a high polish and has a high melting point. It is also odorless, tasteless, and malleable...

, phthalates

Phthalates

Phthalates , or phthalate esters, are esters of phthalic acid and are mainly used as plasticizers . They are used primarily to soften polyvinyl chloride...

, PCB

Polychlorinated biphenyl

Polychlorinated biphenyls are a class of organic compounds with 2 to 10 chlorine atoms attached to biphenyl, which is a molecule composed of two benzene rings. The chemical formula for PCBs is C12H10-xClx...

, and Carbon tetrachloride

Carbon tetrachloride

Carbon tetrachloride, also known by many other names is the organic compound with the formula CCl4. It was formerly widely used in fire extinguishers, as a precursor to refrigerants, and as a cleaning agent...

 have also been recorded. Even though most of these pollutions are bound to particles, leachate

Leachate

Leachate is any liquid that, in passing through matter, extracts solutes, suspended solids or any other component of the material through which it has passed....

 from the eastern part of the tip is believed to leak into the lake. Chlorophyll

Chlorophyll

Chlorophyll is a green pigment found in almost all plants, algae, and cyanobacteria. Its name is derived from the Greek words χλωρος, chloros and φύλλον, phyllon . Chlorophyll is an extremely important biomolecule, critical in photosynthesis, which allows plants to obtain energy from light...

 content have decreased since the 1980s and is at present around 45 μg/l which gives a transparency of 1,5 m.

Flora and fauna

Most common phytoplankton

Phytoplankton

Phytoplankton are the autotrophic component of the plankton community. The name comes from the Greek words φυτόν , meaning "plant", and πλαγκτός , meaning "wanderer" or "drifter". Most phytoplankton are too small to be individually seen with the unaided eye...

 species are filamentous cyanobacteria and diatom

Diatom

Diatoms are a major group of algae, and are one of the most common types of phytoplankton. Most diatoms are unicellular, although they can exist as colonies in the shape of filaments or ribbons , fans , zigzags , or stellate colonies . Diatoms are producers within the food chain...

s, while 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"...

 are represented by 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 copepod

Copepod

Copepods are a group of small crustaceans found in the sea and nearly every freshwater habitat. Some species are planktonic , some are benthic , and some continental species may live in limno-terrestrial habitats and other wet terrestrial places, such as swamps, under leaf fall in wet forests,...

s. Common aquatic plant

Aquatic plant

Aquatic plants are plants that have adapted to living in aquatic environments. They are also referred to as hydrophytes or aquatic macrophytes. These plants require special adaptations for living submerged in water, or at the water's surface. Aquatic plants can only grow in water or in soil that is...

s in the water column includes Rigid Hornwort

Ceratophyllum

Ceratophyllum is a cosmopolitan genus of flowering plants, commonly found in ponds, marshes, and quiet streams in tropical and in temperate regions...

 and 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:...

 coupled with a presence of Nuttall's waterweed

Elodea

Elodea is a genus of aquatic plants often called the waterweeds. Elodea is native to North America and is also widely used as aquarium vegetation. The introduction of some species of Elodea into waterways in parts of Europe, Australia, Africa, Asia, and New Zealand has created a significant problem...

, Frogbit

Frogbit

Frogbits or frog's bits can refer to the following plants:*Hydrocharis morsus-ranae - European frogbit*Limnobium laevigatum - Amazon frogbit, South American frogbit*Limnobium spongia - American frogbit...

, Common Duckweed

Lemna

Lemna is a genus of free-floating aquatic plants from the duckweed family. These rapidly-growing plants have found uses as a model system for studies in community ecology, basic plant biology, in ecotoxicology, in production of biopharmaceuticals, and as a source of animal feeds for agriculture...

, White Waterlily

Nymphaea alba

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

, Amphibious Bistort

Polygonum

Polygonum is a genus in the Polygonaceae family. Common names include knotweed, knotgrass, bistort, tear-thumb, mile-a-minute, and several others. In the Middle English glossary of herbs "Alphita" , it was known as ars-smerte. There have been various opinions about how broadly the genus should be...

, and four species of Pondweed

Potamogeton

Potamogeton is a genus of aquatic, mostly freshwater, plants of the family Potamogetonaceae. Most are known by the common name pondweed, although many unrelated plants may be called pondweed, such as Canadian pondweed...

s.

An inventory of lakebed fauna in 1997 documented 47 species/taxa

Taxon

|thumb|270px|[[African elephants]] form a widely-accepted taxon, the [[genus]] LoxodontaA taxon is a group of organisms, which a taxonomist adjudges to be a unit. Usually a taxon is given a name and a rank, although neither is a requirement...

, predominately freshwater Gastropods

Gastropoda

The Gastropoda or gastropods, more commonly known as snails and slugs, are a large taxonomic class within the phylum Mollusca. The class Gastropoda includes snails and slugs of all kinds and all sizes from microscopic to quite large...

, Beetle

Beetle

Coleoptera is an order of insects commonly called beetles. The word "coleoptera" is from the Greek , koleos, "sheath"; and , pteron, "wing", thus "sheathed wing". Coleoptera contains more species than any other order, constituting almost 25% of all known life-forms...

s, and 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...

. The same year, 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...

, 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...

, 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:...

, and a few other species were documented in the lake. Crayfish

Crayfish

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

 was introduced in 1992 and 1995-96. Except for Seabird

Seabird

Seabirds are birds that have adapted to life within the marine environment. While seabirds vary greatly in lifestyle, behaviour and physiology, they often exhibit striking convergent evolution, as the same environmental problems and feeding niches have resulted in similar adaptations...

s such as 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....

 and Eurasian 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:...

, 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...

 is present on the southern shore. Species of 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 documented includes 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...

, Nyctalus

Nyctalus

The bat genus Nyctalus are members of the family Vespertilionidae or sometimes Evening bats. They are distributed in the temperate and subtropical areas of Europe, Asia and North Africa.There are eight species within this genus:...

, 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....

, 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:...

. Additionally, the area is a great locale for amphibian

Amphibian

Amphibians , are a class of vertebrate animals including animals such as toads, frogs, caecilians, and salamanders. They are characterized as non-amniote ectothermic tetrapods...

s, with a presence of Common Toad

Common Toad

The common toad or European toad is an amphibian widespread throughout Europe, with the exception of Iceland, Ireland and some Mediterranean islands...

 and Moor Frog

Moor Frog

The Moor Frog is a slim, reddish-brown, semi-aquatic amphibian native to Europe and Asia. It is a member of the family Ranidae, or "true frogs".-Taxonomy:...

, and traces of beaver

Beaver

The beaver is a primarily nocturnal, large, semi-aquatic rodent. Castor includes two extant species, North American Beaver and Eurasian Beaver . Beavers are known for building dams, canals, and lodges . They are the second-largest rodent in the world...

have been found around the lake.