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95-528: The name of the lake ( Icelandic mý (" midge ") and vatn ("lake"); "the lake of midges") comes from the large numbers of midges present in the summer. The name Mývatn is sometimes used not only for the lake but the whole surrounding inhabited area. The river Laxá, the lake Mývatn and the surrounding wetlands are protected as a nature reserve (the Mývatn–;Laxá Nature Conservation Area), which occupies 4,400 km (440,000 ha). Since 2000,

190-571: A and b . Their chloroplasts are surrounded by four and three membranes, respectively, and were probably retained from ingested green algae. Chlorarachniophytes , which belong to the phylum Cercozoa , contain a small nucleomorph , which is a relict of the algae's nucleus . Euglenids , which belong to the phylum Euglenozoa , live primarily in fresh water and have chloroplasts with only three membranes. The endosymbiotic green algae may have been acquired through myzocytosis rather than phagocytosis . (Another group with green algae endosymbionts

285-408: A and c , and phycobilins. The shape can vary; they may be of discoid, plate-like, reticulate, cup-shaped, spiral, or ribbon shaped. They have one or more pyrenoids to preserve protein and starch. The latter chlorophyll type is not known from any prokaryotes or primary chloroplasts, but genetic similarities with red algae suggest a relationship there. In the first three of these groups ( Chromista ),

380-438: A marathon around the lake has taken place in the summer. The lake has an average depth of 2.5 metres and a maximum depth of 4.5 metres. The Mývatn area features a tundra climate ( Köppen climate classification ET), bordering on a subarctic climate ( Köppen climate classification Dfc). Summers are typically cool with crisp nights while winters are very long and cold. The lake is fed by nutrient -rich springwater and has

475-528: A polyphyletic group since they do not include a common ancestor , and although their chlorophyll -bearing plastids seem to have a single origin (from symbiogenesis with cyanobacteria ), they were acquired in different ways. Green algae are a prominent examples of algae that have primary chloroplasts derived from endosymbiont cyanobacteria. Diatoms and brown algae are examples of algae with secondary chloroplasts derived from endosymbiotic red algae , which they acquired via phagocytosis . Algae exhibit

570-512: A reflexive pronoun instead. The case of the pronoun depends on the case that the verb governs. As for further classification of verbs, Icelandic behaves much like other Germanic languages, with a main division between weak verbs and strong, and the strong verbs, of which there are about 150 to 200, are divided into six classes plus reduplicative verbs. The basic word order in Icelandic is subject–verb–object . However, as words are heavily inflected,

665-401: A West Scandinavian language. Icelandic is derived from an earlier language Old Norse , which later became Old Icelandic and currently Modern Icelandic. The division between old and modern Icelandic is said to be before and after 1540. East Germanic languages West Germanic languages Icelandic Faroese Norwegian Danish Swedish Around 900 CE, the language spoken in

760-539: A form and capabilities not possessed by the symbiont species alone (they can be experimentally isolated). The photobiont possibly triggers otherwise latent genes in the mycobiont. Trentepohlia is an example of a common green alga genus worldwide that can grow on its own or be lichenised. Lichen thus share some of the habitat and often similar appearance with specialized species of algae ( aerophytes ) growing on exposed surfaces such as tree trunks and rocks and sometimes discoloring them. Coral reefs are accumulated from

855-490: A high abundance of aquatic insects ( Chironomidae ) and Cladocera that form an attractive food supply for ducks. Fifteen species of ducks breed at the site, the largest such number in Europe. The duck species composition has a mixture of European and North American species, and also of boreal and arctic species. Most of the ducks are migratory, arriving in late April to early May from north-western Europe. The commonest species at

950-433: A historical or a formalistic view: -a , -i , and -ur , referring to the endings that these verbs take when conjugated in the first person singular present. Almost all Icelandic verbs have the ending -a in the infinitive, some with á , two with u ( munu , skulu ) one with o ( þvo : "wash") and one with e . Many transitive verbs (i.e. they require an object ), can take

1045-592: A lineage that eventually led to the higher land plants. The innovation that defines these nonalgal plants is the presence of female reproductive organs with protective cell layers that protect the zygote and developing embryo. Hence, the land plants are referred to as the Embryophytes . The term algal turf is commonly used but poorly defined. Algal turfs are thick, carpet-like beds of seaweed that retain sediment and compete with foundation species like corals and kelps , and they are usually less than 15 cm tall. Such

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1140-722: A monophthong and adding either /i/ or /u/ to it. All the vowels can either be long or short; vowels in open syllables are long, and vowels in closed syllables are short. Icelandic retains many grammatical features of other ancient Germanic languages , and resembles Old Norwegian before much of its fusional inflection was lost. Modern Icelandic is still a heavily inflected language with four cases : nominative , accusative , dative and genitive . Icelandic nouns can have one of three grammatical genders : masculine, feminine or neuter. There are two main declension paradigms for each gender: strong and weak nouns , and these are further divided into subclasses of nouns, based primarily on

1235-403: A protectionist language culture, however, this is deep-rooted ideologically primarily in relation to the forms of the language, while Icelanders in general seem to be more pragmatic as to domains of language use. Since the late 16th century, discussion has been ongoing on the purity of the Icelandic language. The bishop Oddur Einarsson wrote in 1589 that the language has remained unspoiled since

1330-478: A red dye derived from it. The Latinization, fūcus , meant primarily the cosmetic rouge. The etymology is uncertain, but a strong candidate has long been some word related to the Biblical פוך ( pūk ), 'paint' (if not that word itself), a cosmetic eye-shadow used by the ancient Egyptians and other inhabitants of the eastern Mediterranean. It could be any color: black, red, green, or blue. The study of algae

1425-584: A result, the Irish language has had some influence on both Faroese and Icelandic. The oldest preserved texts in Icelandic were written around 1100. Many of the texts are based on poetry and laws traditionally preserved orally. The most famous of the texts, which were written in Iceland from the 12th century onward, are the sagas of Icelanders , which encompass the historical works and the Poetic Edda . The language of

1520-624: A standard established in the 19th century, primarily by the Danish linguist Rasmus Rask . It is based strongly on an orthography laid out in the early 12th century by a document referred to as the First Grammatical Treatise by an anonymous author, who has later been referred to as the First Grammarian. The later Rasmus Rask standard was a re-creation of the old treatise, with some changes to fit concurrent Germanic conventions, such as

1615-451: A swarm of fissures that cut through the volcano from north to south. The recent activity was characterized by periods of slow land rise, interspersed by shorter periods of rapid subsidence, underground magma bursts, rifting, earthquakes and eruptions (nine in all). This is an example of the process of continental drift in Iceland. A central volcano and its associated fissure swarm is called

1710-463: A turf may consist of one or more species, and will generally cover an area in the order of a square metre or more. Some common characteristics are listed: Many algae, particularly species of the Characeae , have served as model experimental organisms to understand the mechanisms of the water permeability of membranes, osmoregulation , turgor regulation , salt tolerance , cytoplasmic streaming , and

1805-675: A volcanic system. The Krafla volcanic system is one of several such systems which together form the volcanic zone of Iceland. A few rhyolite mountains border the Krafla central volcano (Hlíðarfjall [ˈl̥iːðarˌfjatl̥] , Jörundur [ˈjœːrʏntʏr̥] , Hrafntinnuhryggur [ˈr̥apn̥ˌtʰɪnːʏˌr̥ɪkːʏr̥] ). Because of its volcanic origin, the lake was formerly mined for diatomite , but this ceased in 2004. Icelandic language Icelandic ( / aɪ s ˈ l æ n d ɪ k / eyess- LAN -dik ; endonym : íslenska , pronounced [ˈistlɛnska] )

1900-989: A wide range of reproductive strategies, from simple asexual cell division to complex forms of sexual reproduction via spores . Algae lack the various structures that characterize plants (which evolved from freshwater green algae), such as the phyllids (leaf-like structures) and rhizoids of bryophytes ( non-vascular plants ), and the roots , leaves and other xylemic / phloemic organs found in tracheophytes ( vascular plants ). Most algae are autotrophic , although some are mixotrophic , deriving energy both from photosynthesis and uptake of organic carbon either by osmotrophy , myzotrophy or phagotrophy . Some unicellular species of green algae, many golden algae , euglenids , dinoflagellates , and other algae have become heterotrophs (also called colorless or apochlorotic algae), sometimes parasitic , relying entirely on external energy sources and have limited or no photosynthetic apparatus. Some other heterotrophic organisms, such as

1995-508: Is a North Germanic language from the Indo-European language family spoken by about 314,000 people, the vast majority of whom live in Iceland , where it is the national language. Since it is a West Scandinavian language , it is most closely related to Faroese , western Norwegian dialects , and the extinct language Norn . It is not mutually intelligible with the continental Scandinavian languages ( Danish , Norwegian , and Swedish ) and

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2090-558: Is an extension of the Mid-Atlantic Ridge . All geological formations are quite recent, dating from the Ice Age and postglacial times. The bedrock of the moors west of Mývatn is made up of interglacial lava flows. Most of the mountains in the vicinity of the lake were formed by eruptions under the ice sheet in the glacial periods of the Ice Age. Eruptions that melted their way up through

2185-454: Is an informal term for any organisms of a large and diverse group of photosynthetic eukaryotes , which include species from multiple distinct clades . Such organisms range from unicellular microalgae such as Chlorella , Prototheca and the diatoms , to multicellular macroalgae such as the giant kelp , a large brown alga which may grow up to 50 metres (160 ft) in length. Most algae are aquatic organisms and lack many of

2280-472: Is distinguished by a wide assortment of irregular declensions. Icelandic vocabulary is also deeply conservative, with the country's language regulator maintaining an active policy of coining terms based on older Icelandic words rather than directly taking in loanwords from other languages. Aside from the 300,000 Icelandic speakers in Iceland, Icelandic is spoken by about 8,000 people in Denmark, 5,000 people in

2375-404: Is evident in general language discourses, in polls, and in other investigations into Icelandic language attitudes. The general consensus on Icelandic language policy has come to mean that language policy and language ideology discourse are not predominantly state or elite driven; but rather, remain the concern of lay people and the general public. The Icelandic speech community is perceived to have

2470-477: Is known as rootless cones or pseudocraters. A group of such craters at Skútustaðir [ˈskuːtʏˌstaːðɪr̥] on the south shore of the lake is protected as a natural monument. Other rootless cone groups in this lava field are in the valley Laxárdalur and the plain Aðaldalur. The formation of rootless cones halted the advance of the lava in some places creating temporary lava lakes. The lava eventually drained from

2565-511: Is more distinct from the most widely spoken Germanic languages, English and German . The written forms of Icelandic and Faroese are very similar, but their spoken forms are not mutually intelligible . The language is more conservative than most other Germanic languages. While most of them have greatly reduced levels of inflection (particularly noun declension ), Icelandic retains a four- case synthetic grammar (comparable to German , though considerably more conservative and synthetic) and

2660-550: Is most commonly called phycology (from Greek phykos  'seaweed'); the term algology is falling out of use. One definition of algae is that they "have chlorophyll as their primary photosynthetic pigment and lack a sterile covering of cells around their reproductive cells ". On the other hand, the colorless Prototheca under Chlorophyta are all devoid of any chlorophyll. Although cyanobacteria are often referred to as "blue-green algae", most authorities exclude all prokaryotes , including cyanobacteria, from

2755-647: Is not very well known and because those Icelanders not proficient in the other Scandinavian languages often have a sufficient grasp of English to communicate with institutions in that language (although there is evidence that the general English skills of Icelanders have been somewhat overestimated). The Nordic countries have committed to providing services in various languages to each other's citizens, but this does not amount to any absolute rights being granted, except as regards criminal and court matters. All Icelandic stops are voiceless and are distinguished as such by aspiration . Stops are realised post-aspirated when at

2850-536: Is quite different from those of reds and browns, because they have distinct nodes, separated by internode 'stems'; whorls of branches reminiscent of the horsetails occur at the nodes. Conceptacles are another polyphyletic trait; they appear in the coralline algae and the Hildenbrandiales , as well as the browns. Most of the simpler algae are unicellular flagellates or amoeboids , but colonial and nonmotile forms have developed independently among several of

2945-550: Is still a conscious effort to create new words, especially for science and technology, with many societies publishing dictionaries, some with the help of The Icelandic Language Committee ( Íslensk málnefnd ). The Icelandic alphabet is notable for its retention of three old letters that no longer exist in the English alphabet : Þ, þ ( þorn , modern English "thorn"), Ð, ð ( eð , anglicised as "eth" or "edh") and Æ, æ (æsc, anglicised as "ash" or "asc"), with þ and ð representing

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3040-519: Is the Latin word for 'seaweed' and retains that meaning in English. The etymology is obscure. Although some speculate that it is related to Latin algēre , 'be cold', no reason is known to associate seaweed with temperature. A more likely source is alliga , 'binding, entwining'. The Ancient Greek word for 'seaweed' was φῦκος ( phŷkos ), which could mean either the seaweed (probably red algae) or

3135-423: Is the dinoflagellate genus Lepidodinium , which has replaced its original endosymbiont of red algal origin with one of green algal origin. A nucleomorph is present, and the host genome still have several red algal genes acquired through endosymbiotic gene transfer. Also the euglenid and chlorarachniophyte genome contain genes of apparent red algal ancestry) These groups have chloroplasts containing chlorophylls

3230-732: The Calymmian period , early in Boring Billion , but it is difficult to track the key events because of so much time gap. Primary symbiogenesis gave rise to three divisions of archaeplastids , namely the Viridiplantae ( green algae and later plants ), Rhodophyta ( red algae ) and Glaucophyta ("grey algae"), whose plastids further spread into other protist lineages through eukaryote-eukaryote predation , engulfments and subsequent endosymbioses (secondary and tertiary symbiogenesis). This process of serial cell "capture" and "enslavement" explains

3325-609: The Infusoria (microscopic organisms). Unlike macroalgae , which were clearly viewed as plants, microalgae were frequently considered animals because they are often motile. Even the nonmotile (coccoid) microalgae were sometimes merely seen as stages of the lifecycle of plants, macroalgae, or animals. Although used as a taxonomic category in some pre-Darwinian classifications, e.g., Linnaeus (1753), de Jussieu (1789), Lamouroux (1813), Harvey (1836), Horaninow (1843), Agassiz (1859), Wilson & Cassin (1864), in further classifications,

3420-588: The International Association for Lichenology to be "an association of a fungus and a photosynthetic symbiont resulting in a stable vegetative body having a specific structure". The fungi, or mycobionts, are mainly from the Ascomycota with a few from the Basidiomycota . In nature, they do not occur separate from lichens. It is unknown when they began to associate. One or more mycobiont associates with

3515-582: The Late Cambrian / Early Ordovician period, from sessile shallow freshwater charophyte algae much like Chara , which likely got stranded ashore when riverine / lacustrine water levels dropped during dry seasons . These charophyte algae probably already developed filamentous thalli and holdfasts that superficially resembled plant stems and roots , and probably had an isomorphic alternation of generations . They perhaps evolved some 850 mya and might even be as early as 1  Gya during

3610-582: The Parliament in 2011, Icelandic is "the national language of the Icelandic people and the official language in Iceland"; moreover, "[p]ublic authorities shall ensure that its use is possible in all areas of Icelandic society". Iceland is a member of the Nordic Council , a forum for co-operation between the Nordic countries, but the council uses only Danish, Norwegian, and Swedish as its working languages (although

3705-976: The Vindhya basin have been dated to 1.6 to 1.7 billion years ago. Because of the wide range of algae types, they have increasingly different industrial and traditional applications in human society. Traditional seaweed farming practices have existed for thousands of years and have strong traditions in East Asia food cultures. More modern algaculture applications extend the food traditions for other applications, including cattle feed, using algae for bioremediation or pollution control, transforming sunlight into algae fuels or other chemicals used in industrial processes, and in medical and scientific applications. A 2020 review found that these applications of algae could play an important role in carbon sequestration to mitigate climate change while providing lucrative value-added products for global economies. The singular alga

3800-601: The apicomplexans are also parasites derived from ancestors that possessed plastids, but are not included in any group traditionally seen as algae. Algae are polyphyletic thus their origin cannot be traced back to single hypothetical common ancestor . It is thought that they came into existence when photosynthetic coccoid cyanobacteria got phagocytized by a unicellular heterotrophic eukaryote (a protist ), giving rise to double-membranous primary plastids . Such symbiogenic events (primary symbiogenesis) are believed to have occurred more than 1.5 billion years ago during

3895-435: The apicomplexans , are also derived from cells whose ancestors possessed chlorophyllic plastids, but are not traditionally considered as algae. Algae have photosynthetic machinery ultimately derived from cyanobacteria that produce oxygen as a byproduct of splitting water molecules , unlike other organisms that conduct anoxygenic photosynthesis such as purple and green sulfur bacteria . Fossilized filamentous algae from

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3990-501: The bishop and members of parliament . Early Icelandic vocabulary was largely Old Norse with a few words being Celtic from when Celts first settled in Iceland. The introduction of Christianity to Iceland in the 11th century brought with it a need to describe new religious concepts . The majority of new words were taken from other Scandinavian languages ; kirkja ("church"), for example. Numerous other languages have influenced Icelandic: French brought many words related to

4085-545: The calcareous exoskeletons of marine invertebrates of the order Scleractinia (stony corals ). These animals metabolize sugar and oxygen to obtain energy for their cell-building processes, including secretion of the exoskeleton, with water and carbon dioxide as byproducts. Dinoflagellates (algal protists) are often endosymbionts in the cells of the coral-forming marine invertebrates, where they accelerate host-cell metabolism by generating sugar and oxygen immediately available through photosynthesis using incident light and

4180-460: The crater lake Víti [ˈviːtɪ] . Later lava flowed from Leirhnjúkur [ˈleirˌn̥juːkʏr̥] down to the north end of Mývatn, destroying two farms. The Mývatnseldar eruptions are quite similar in character to the recent volcanic activity near Krafla in 1975–1984. The source of both is a central volcano lying between Krafla and Gæsafjöll. Inside the volcano resides a magma chamber from which molten magma periodically bursts into

4275-444: The genitive singular and nominative plural endings of a particular noun. For example, within the strong masculine nouns, there is a subclass (class 1) that declines with -s ( hests ) in the genitive singular and -ar ( hestar ) in the nominative plural. However, there is another subclass (class 3) of strong masculine nouns that always declines with -ar ( hlutar ) in the genitive singular and -ir ( hlutir ) in

4370-470: The voiceless and voiced "th" sounds (as in English thin and this ), respectively, and æ representing the diphthong /ai/ which does not exist in English. The complete Icelandic alphabet is: The letters with diacritics , such as á and ö , are for the most part treated as separate letters and not variants of their derivative vowels. The letter é officially replaced je in 1929, although it had been used in early manuscripts (until

4465-720: The "algae" are seen as an artificial, polyphyletic group. Throughout the 20th century, most classifications treated the following groups as divisions or classes of algae: cyanophytes , rhodophytes , chrysophytes , xanthophytes , bacillariophytes , phaeophytes , pyrrhophytes ( cryptophytes and dinophytes ), euglenophytes , and chlorophytes . Later, many new groups were discovered (e.g., Bolidophyceae ), and others were splintered from older groups: charophytes and glaucophytes (from chlorophytes), many heterokontophytes (e.g., synurophytes from chrysophytes, or eustigmatophytes from xanthophytes), haptophytes (from chrysophytes), and chlorarachniophytes (from xanthophytes). With

4560-445: The 11th century, when the first texts were written on vellum . Modern speakers can understand the original sagas and Eddas which were written about eight hundred years ago. The sagas are usually read with updated modern spelling and footnotes, but otherwise are intact (as with recent English editions of Shakespeare's works). With some effort, many Icelanders can also understand the original manuscripts. According to an act passed by

4655-590: The 14th century) and again periodically from the 18th century. The letter z was formerly in the Icelandic alphabet, but it was officially removed in 1974, except in people's names. Ragnarsson, Baldur (1992). Mál og málsaga [ Language and language history ] (in Icelandic). Mál og Menning. ISBN   978-9979-3-0417-3 . Algae Algae ( UK : / ˈ æ l ɡ iː / AL -ghee , US : / ˈ æ l dʒ iː / AL -jee ; sg. : alga / ˈ æ l ɡ ə / AL -gə )

4750-462: The 16th century, especially in vowels (in particular, á , æ , au , and y / ý ). The letters -ý & -y lost their original meaning and merged with -í & -i in the period 1400 - 1600. Around the same time or a little earlier the letter -æ originally signifying a simple vowel, a type of open -e, formed into the double vowel -ai, a double vowel absent in the original Icelandic. The modern Icelandic alphabet has developed from

4845-559: The Barrow's goldeneye (of about 2000 individuals) relies entirely on the habitat provided by the Mývatn ;Laxá water system and its surrounding lava fields. Most of the Barrow's goldeneyes overwinter there, using ice-free areas kept open by emerging spring water (both warm and cold) and in the strong river current. This species is a hole-nester, in North America using tree-holes, but at Mývatn

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4940-586: The Faroes was Old Norse , which Norse settlers had brought with them during the time of the settlement of Faroe Islands ( landnám ) that began in 825. However, many of the settlers were not from Scandinavia , but descendants of Norse settlers in the Irish Sea region. In addition, women from Norse Ireland, Orkney , or Shetland often married native Scandinavian men before settling in the Faroe Islands and Iceland. As

5035-479: The Mývatn Research Station. There is a long tradition of harvesting duck eggs for home use on the local farms. To ensure sustainability, the harvesting follows strict age-old rules of leaving at least four eggs in a nest for the duck to incubate. The lava flows and moorlands surrounding the lake are home to rock ptarmigans and occasionally gyr falcons may be present. Mývatn is one of the few places in

5130-587: The United States, and more than 1,400 people in Canada, notably in the region known as New Iceland in Manitoba which was settled by Icelanders beginning in the 1880s. The state-funded Árni Magnússon Institute for Icelandic Studies serves as a centre for preserving the medieval Icelandic manuscripts and studying the language and its literature. The Icelandic Language Council, comprising representatives of universities,

5225-670: The abandonment of plant-animal dichotomous classification, most groups of algae (sometimes all) were included in Protista , later also abandoned in favour of Eukaryota . However, as a legacy of the older plant life scheme, some groups that were also treated as protozoans in the past still have duplicated classifications (see ambiregnal protists ). Some parasitic algae (e.g., the green algae Prototheca and Helicosporidium , parasites of metazoans, or Cephaleuros , parasites of plants) were originally classified as fungi , sporozoans , or protistans of incertae sedis , while others (e.g.,

5320-432: The above examples, the conjugated verbs veit and fór are always the second element in their respective clauses. A distinction between formal and informal address ( T–V distinction ) had existed in Icelandic from the 17th century, but use of the formal variant weakened in the 1950s and rapidly disappeared. It no longer exists in regular speech, but may occasionally be found in pre-written speeches addressed to

5415-574: The arts, journalists, teachers, and the Ministry of Culture, Science and Education , advises the authorities on language policy . Since 1995, on 16 November each year, the birthday of 19th-century poet Jónas Hallgrímsson is celebrated as Icelandic Language Day . Icelandic is an Indo-European language and belongs to the North Germanic group of the Germanic languages . Icelandic is further classified as

5510-408: The beginning of the word, but pre-aspirated when occurring within a word. Scholten (2000 , p. 22) includes three extra phones: [ʔ l̥ˠ lˠ] . Word-final voiced consonants are devoiced pre-pausally, so that dag ('day (acc.)') is pronounced as [ˈtaːx] and dagur ('day (nom.)') is pronounced [ˈtaːɣʏr̥] . Icelandic has 8 monophthongs and 5 diphthongs. The diphthongs are created by taking

5605-464: The birds use cavities in the lava for nesting. The other duck species nest abundantly in the numerous islands of the lake and the surrounding marshlands. Other common waterbirds include the Slavonian grebe , red-necked phalarope , great northern diver , red-throated diver and whooper swan . The lake is included in an important bird area . Bird populations have been monitored annually since 1975 by

5700-451: The carbon dioxide produced by the host. Reef-building stony corals ( hermatypic corals ) require endosymbiotic algae from the genus Symbiodinium to be in a healthy condition. The loss of Symbiodinium from the host is known as coral bleaching , a condition which leads to the deterioration of a reef. Endosymbiontic green algae live close to the surface of some sponges, for example, breadcrumb sponges ( Halichondria panicea ). The alga

5795-420: The chloroplast has four membranes, retaining a nucleomorph in cryptomonads , and they likely share a common pigmented ancestor, although other evidence casts doubt on whether the heterokonts , Haptophyta , and cryptomonads are in fact more closely related to each other than to other groups. The typical dinoflagellate chloroplast has three membranes, but considerable diversity exists in chloroplasts within

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5890-535: The close of the Ice Age, about 10,000 years ago, the Mývatn basin was covered by a glacier which pushed up huge end moraines which can still be seen at the north end of the lake. After the glacier started melting, a glacial lake was dammed up in the Mývatn depression until the glacier retreated from the present course of Laxá river. Postglacial volcanism in the Mývatn district may be divided into three cycles. The Lúdent [ˈluːˌtɛn̥t] cycle commenced shortly after

5985-462: The close of the Ice Age. The explosion crater ( tephra ring) Lúdent dates from this cycle. Its eruption was followed by a number of small fissure eruptions. About 3800 years ago the shield volcano Ketildyngja [ˈcʰɛːtɪlˌtiɲca] was formed about 25 km south-east of Mývatn, and from it a huge lava flow, the Older Laxá-lava, spread over the southern part of the district, plunged down

6080-624: The composition of the three major groups of algae. Their lineage relationships are shown in the figure in the upper right. Many of these groups contain some members that are no longer photosynthetic. Some retain plastids, but not chloroplasts, while others have lost plastids entirely. Phylogeny based on plastid not nucleocytoplasmic genealogy: Cyanobacteria Glaucophytes Rhodophytes Stramenopiles Cryptophytes Haptophytes Euglenophytes Chlorarachniophytes Chlorophytes Charophytes Land plants (Embryophyta) These groups have green chloroplasts containing chlorophylls

6175-494: The council does publish material in Icelandic). Under the Nordic Language Convention , since 1987 Icelandic citizens have had the right to use Icelandic when interacting with official bodies in other Nordic countries, without becoming liable for any interpretation or translation costs. The convention covers visits to hospitals, job centres, the police, and social security offices. It does not have much effect since it

6270-502: The court and knightship; words in the semantic field of trade and commerce have been borrowed from Low German because of trade connections. In the late 18th century, linguistic purism began to gain noticeable ground in Iceland and since the early 19th century it has been the linguistic policy of the country. Nowadays, it is common practice to coin new compound words from Icelandic derivatives. Icelandic personal names are patronymic (and sometimes matronymic ) in that they reflect

6365-436: The definition of algae. The algae contain chloroplasts that are similar in structure to cyanobacteria. Chloroplasts contain circular DNA like that in cyanobacteria and are interpreted as representing reduced endosymbiotic cyanobacteria . However, the exact origin of the chloroplasts is different among separate lineages of algae, reflecting their acquisition during different endosymbiotic events. The table below describes

6460-493: The distinct cell and tissue types, such as stomata , xylem and phloem that are found in land plants . The largest and most complex marine algae are called seaweeds . In contrast, the most complex freshwater forms are the Charophyta , a division of green algae which includes, for example, Spirogyra and stoneworts . Algae that are carried passively by water are plankton , specifically phytoplankton . Algae constitute

6555-425: The diversity of photosynthetic eukaryotes. Recent genomic and phylogenomic approaches have significantly clarified plastid genome evolution , the horizontal movement of endosymbiont genes to the "host" nuclear genome , and plastid spread throughout the eukaryotic tree of life . Fossils of isolated spores suggest land plants may have been around as long as 475  million years ago (mya) during

6650-439: The exclusive use of k rather than c . Various archaic features, such as the letter ð , had not been used much in later centuries. Rask's standard constituted a major change in practice. Later 20th-century changes include the use of é instead of je and the replacement of z with s in 1974. Apart from the addition of new vocabulary, written Icelandic has not changed substantially since

6745-432: The first to divide macroscopic algae into four divisions based on their pigmentation. This is the first use of a biochemical criterion in plant systematics. Harvey's four divisions are: red algae (Rhodospermae), brown algae (Melanospermae), green algae (Chlorospermae), and Diatomaceae. At this time, microscopic algae were discovered and reported by a different group of workers (e.g., O. F. Müller and Ehrenberg ) studying

6840-530: The genera Volvox and Corallina , and a species of Acetabularia (as Madrepora ), among the animals. In 1768, Samuel Gottlieb Gmelin (1744–1774) published the Historia Fucorum , the first work dedicated to marine algae and the first book on marine biology to use the then new binomial nomenclature of Linnaeus. It included elaborate illustrations of seaweed and marine algae on folded leaves. W. H. Harvey (1811–1866) and Lamouroux (1813) were

6935-446: The generation of action potentials . Plant hormones are found not only in higher plants, but in algae, too. Some species of algae form symbiotic relationships with other organisms. In these symbioses, the algae supply photosynthates (organic substances) to the host organism providing protection to the algal cells. The host organism derives some or all of its energy requirements from the algae. Examples are: Lichens are defined by

7030-538: The green algae Phyllosiphon and Rhodochytrium , parasites of plants, or the red algae Pterocladiophila and Gelidiocolax mammillatus , parasites of other red algae, or the dinoflagellates Oodinium , parasites of fish) had their relationship with algae conjectured early. In other cases, some groups were originally characterized as parasitic algae (e.g., Chlorochytrium ), but later were seen as endophytic algae. Some filamentous bacteria (e.g., Beggiatoa ) were originally seen as algae. Furthermore, groups like

7125-563: The group, and a number of endosymbiotic events apparently occurred. The Apicomplexa , a group of closely related parasites, also have plastids called apicoplasts , which are not photosynthetic, but appear to have a common origin with dinoflagellate chloroplasts. Linnaeus , in Species Plantarum (1753), the starting point for modern botanical nomenclature , recognized 14 genera of algae, of which only four are currently considered among algae. In Systema Naturae , Linnaeus described

7220-453: The groups. Some of the more common organizational levels, more than one of which may occur in the lifecycle of a species, are In three lines, even higher levels of organization have been reached, with full tissue differentiation. These are the brown algae, —some of which may reach 50 m in length ( kelps ) —the red algae, and the green algae. The most complex forms are found among the charophyte algae (see Charales and Charophyta ), in

7315-417: The ice formed table mountains (Bláfjall [ˈplauːˌfjatl̥] , Sellandafjall [ˈsɛlˌlantaˌfjatl̥] , Búrfell [ˈpurˌfɛtl̥] , Gæsafjöll [ˈcaiːsaˌfjœtl̥] ), those which did not formed hyaloclastite ridges (Vindbelgjarfjall [ˈvɪntˌpɛlcarˌfjatl̥] , Námafjall [ˈnauːmaˌfjatl̥] , Dalfjall [ˈtalˌfjatl̥] , Hvannfell [ˈkʰvanːˌfɛtl̥] ). At

7410-422: The immediate father or mother of the child and not the historic family lineage. This system, which was formerly used throughout the Nordic area and beyond, differs from most Western systems of family name . In most Icelandic families, the ancient tradition of patronymics is still in use; i.e. a person uses their father's name (usually) or mother's name (increasingly in recent years) in the genitive form followed by

7505-542: The lake is the tufted duck with 6,000 pairs present, whilst the second most abundant species is the greater scaup with 1,500 pairs. Other common species include the Barrow's goldeneye , 700 pairs of red-breasted merganser , 1000 pairs of Eurasian wigeon , around 300 pairs of gadwall , 200 pairs of mallard , around 350 pairs of common scoter , 150 pairs of long-tailed duck and 75 pairs of Eurasian teal . The northern shoveler and northern pintail also regularly breed at

7600-402: The lake, albeit in smaller numbers, whilst common pochard used to breed regularly, but they have not done so regularly since the 1950s. The outflowing Laxá river contains around 250 pairs of harlequin duck and there is a large colony of eider at the river mouth some 50 km away from Mývatn. The Barrow's goldeneye and the harlequin duck are both nearctic duck species. The population of

7695-470: The lakes, leaving behind a forest of rock pillars. The biggest of these formations is named Dimmuborgir . At another place, Höfði [ˈhœvðɪ] , the pillars stand in the lake water. The lava created by the Þrengslaborgir eruption is known as the Younger Laxá Lava. The Mývatn district lies on the western border of the volcanic zone which cuts across north-eastern Iceland from north to south and

7790-417: The late phase of the Boring Billion . A range of algal morphologies is exhibited, and convergence of features in unrelated groups is common. The only groups to exhibit three-dimensional multicellular thalli are the reds and browns , and some chlorophytes . Apical growth is constrained to subsets of these groups: the florideophyte reds, various browns, and the charophytes. The form of charophytes

7885-544: The lavafield between Reykjahlíð and Vogar . Approximately 200 years later a vast lava flow, the Younger Laxá Lava, was erupted (see above). The lava dammed up the present lake Mývatn and also the lakes Sandvatn [ˈsantˌvahtn̥] , Grænavatn [ˈkraiːnaˌvahtn̥] and Arnarvatn [ˈa(r)tnarˌvahtn̥] . The third volcanic cycle began with the Mývatnseldar [ˈmiːˌvasːˌɛltar̥] eruptions in 1724–1729 which commenced with an explosion that formed

7980-639: The middle voice is a voice or simply an independent class of verbs of its own, as every middle-voice verb has an active-voice ancestor, but sometimes with drastically different meaning, and the middle-voice verbs form a conjugation group of their own. Examples are koma ("come") vs. komast ("get there"), drepa ("kill") vs. drepast ("perish ignominiously") and taka ("take") vs. takast ("manage to"). Verbs have up to ten tenses, but Icelandic, like English, forms most of them with auxiliary verbs . There are three or four main groups of weak verbs in Icelandic, depending on whether one takes

8075-418: The morpheme -son ("son") or -dóttir ("daughter") in lieu of family names. In 2019, changes were announced to the laws governing names. Icelanders who are officially registered with non-binary gender will be permitted to use the suffix -bur ("child of") instead of -son or -dóttir . A core theme of Icelandic language ideologies is grammatical, orthographic and lexical purism for Icelandic. This

8170-445: The nominative plural. Additionally, Icelandic permits a quirky subject , that is, certain verbs have subjects in an oblique case (i.e. other than the nominative). Nouns, adjectives and pronouns are declined in the four cases and for number in the singular and plural. Verbs are conjugated for tense , mood , person , number and voice . There are three voices: active, passive and middle (or medial), but it may be debated whether

8265-459: The sagas is Old Icelandic , a western dialect of Old Norse . The Dano-Norwegian , then later Danish rule of Iceland from 1536 to 1918 had little effect on the evolution of Icelandic (in contrast to the Norwegian language), which remained in daily use among the general population. Though more archaic than the other living Germanic languages, Icelandic changed markedly in pronunciation from the 12th to

8360-405: The same phycobiont species, from the green algae, except that alternatively, the mycobiont may associate with a species of cyanobacteria (hence "photobiont" is the more accurate term). A photobiont may be associated with many different mycobionts or may live independently; accordingly, lichens are named and classified as fungal species. The association is termed a morphogenesis because the lichen has

8455-446: The time the ancient literature of Iceland was written. Later in the 18th century the purism movement grew and more works were translated into Icelandic, especially in areas that Icelandic had hardly ever been used in. Many neologisms were introduced, with many of them being loan-translations. In the early 19th century, due to the influence of romanticism , importance was put on the purity of spoken language as well. The written language

8550-470: The valley Laxárdalur to the lowland plain of Aðaldalur [ˈaːðalˌtaːlʏr̥] where it entered the Arctic Ocean about 50 km away from Mývatn. The crater row that formed along the eruptive fissure is called Þrengslaborgir [ˈθreiŋstlaˌpɔrcɪr̥] (or Lúdentarborgir [ˈluːˌtɛn̥tarˌpɔrcɪr̥] ) and has often been used as a textbook example of this type of volcanic activity. There

8645-517: The valley Laxárdalur and flowed almost to the sea. This lava dammed up the first Mývatn, which was about as large as the present lake. The second volcanic cycle, the Hverfjall cycle, began 2500 years ago with a gigantic but brief eruption, which formed the explosion crater (tephra ring) Hverfjall (also named Hverfell). An eruption in Jarðbaðshólar [ˈjarðˌpaðsˌhouːlar̥] followed, producing

8740-455: The word order is fairly flexible, and every combination may occur in poetry; SVO, SOV, VSO, VOS, OSV and OVS are all allowed for metrical purposes. However, as with most Germanic languages, Icelandic usually complies with the V2 word order restriction, so the conjugated verb in Icelandic usually appears as the second element in the clause, preceded by the word or phrase being emphasised. For example: In

8835-425: The world where marimo grows naturally. Also known as Cladophora ball it is a species of filamentous green algae . Due to environmental factors their population has rapidly declined and the algae appeared to have become extinct in 2013. The ecosystem is now improving and small marimo balls are forming again. Mývatn was created about 2300 years ago by a large fissure eruption of basaltic lava. The lava flowed down

8930-425: Was a large lake in the area at the time, a precursor of the present-day Mývatn. When the lava encountered the lake some of the water-logged lake sediment was trapped underneath it, generating steam explosions. By repeated explosions in a number of locations, groups of craters built up and now dominate the landscape on the shore of Lake Mývatn and also form some of the islands in the lake. This type of lava formation

9025-479: Was also brought closer to the spoken language, as the sentence structure of literature had previously been influenced by Danish and German . The changes brought by the purism movement have had the most influence on the written language, as many speakers use foreign words freely in speech but try to avoid them in writing. The success of the many neologisms created from the movement has also been variable as some loanwords have not been replaced with native ones. There

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