No original Mytilus populations lived in southern Africa, but the Mediterranean mussel was introduced from Europe in 1984 and is now the dominant low intertidal mussel on the West Coast. The sites from the German coast of the Baltic sea consisted of three transects from main harbours (Kiel, Warnenünde, Swinemünde) to the open sea. [7] Mytilus galloprovincialis is mainly cultured in coastal waters from Galicia (NW Spain) to the northern shores of the Mediterranean Sea. The Mediterranean mussel (Mytilus galloprovincialis) is a species of bivalve, a marine mollusc in the family Mytilidae. However, production has also been reported from some southern Mediterranean countries, the Russian Federation, Ukraine, and South Africa. Hence, differentiation among M. edulis, M. trossulus, and the rest of Mytilus species was achieved in a first step. NOAA/NMFS, Washington DC., USA. Mytilus galloprovincialis is one of the three principal, closely related species in the Mytilus edulis complex of blue mussels, which collectively are widely distributed on the temperate to subarctic coasts of both the Northern and Southern Hemispheres, and often are dominant inhabitants on hard substrates of the intertidal and nearshore habitats. Lewis JR & Seed R 1969. Silting of the bottoms where rafts are located may induce a problem for the benthic communities located underneath. It is a smooth-shelled mussel with a slightly broader base than that of the black mussel (Choromytilus meridionalis), with which it is often confused in South Africa. The exertions by the hemolymph of the species are considered a useful biomarker of the immune activity and therefore of the health of mussels. They also grow along the rias mainly on rocky areas, cliffs, and boulders. Geographical Range: A C F M An. The losses occurring from predation by starfish, crabs, and fishes is not substantial, and the parasites. Skibinski DO, Beardmore JA, Cross TF. M. galloprovincialis is not resistant to infection by Mytilicola intestinalis, but appears to be less affected by the parasite than is Mytilus edulis. Die Gemeine Miesmuschel oder Essbare Miesmuschel (Mytilus edulis) (lateinisch edulis = essbar) ist eine Muschel-Art aus der Familie der Miesmuscheln (Mytilidae). Die drei Arten sind gehäusemorphologisch kaum zu unterscheiden und können daher nur durch Allozym Mytilus edulis / M. gallopro vinci alis / M. trossulus. Man y. Mytilus edulis zhurmunski Scarlato & Starobogatov, 1979 Mytilus edulis zhirmunskii Scarlato & Starobogatov, 1979 Mytilus edulis diegensis Coe, 1945 Mytilus galloprovincialis trepida Milaschewitsch, 1916 Mytilus galloprovincialis frequens Milaschewitsch, 1909 Mytilus orbicularis Pallary, 1903 Mytilus galloprovincialis eduliformis Monterosato, 1891 In turn, this favours the growth of mussels. The enormous amount of shells produced is being disposed in a variety of industrial ways but more diversification is needed. & Figueras, A. The genetically distinct lineage of M. edulis present in the Southern Hemisphere has been attributed to subspecies Mytilus edulis platensis (now Mytilus platensis). =Mytilus edulis Linnaeus, 1758 =Mytilus edulis aoteanus Powell, 1958 =Mytilus edulis galloprovincialis Lamarck, 1819 =Mytilus planulatus Lamarck, 1819. Farmers suspend the mussels from their own rafts or sell them to other farmers. Mytilus galloprovincialis wird umgangssprachlich oft als Mittelmeer-Miesmuschel bezeichnet. & Beckley, L.E (2005). FIM: AQ/Conf./76/R.7, Kyoto, 20 pp. The marketable mussels are packed by women in nylon bags and taken in boats directly to the depuration plants, or to canning factories. References and Publications. Fundacion 'Pedro Barrie de la Maza'. "Genetic diversity and connectivity within spp. Annual productivity in the rias averages 10.5 mg carbon/litre/hr. To increase production, suitable new areas must be found. Desarrollo actual del cultivo del mejillon (Mytilus edulis L.) y posibilidades de expansion. This should be solved by strong policies directed towards correct management of the fouling and silt accumulated by the hanging ropes. The price is about 60 pesetas/kg (EUR 1 = 166.386 pesetas). The distribution of Mytilus edulis Linnaeus, M. galloprovincialis Lamarck, and their hybrids was examined in mussel populations in southwest England in 1996 and 1998. An emphasis on environmentally friendly practices should be encouraged. Thus a production limit is approaching; probably the number of rafts should be controlled. FAO Technical Conference on Aquaculture. NOAA Technical Report NMFS 129:165-190. Hinsichtlich der NordseeProbenahmeflächen kann zur Zeit - nicht ausgeschlossen werden, dass eine Introgression bzw. Paris. There is a continuous upwelling of cold water that is rich in nutrients; these, along with nutrients which wash down from the hills during heavy rains (mean annual precipitation is 1250 mm) probably stimulate an abundance of phytoplankton. Figueras, A. Die Gattung Mytilus ist eine weltweit verbreitete Gattung der Muscheln (Bivalvia) und die Typusgattung der Familie der Miesmuscheln (Mytilidae). In 1958 its cost had reached 250 000 pesetas; of this, 150 000 pesetas were for carpentry, 21 000 for the chain and anchorage, 65 000 for the esparto grass ropes (. 43: 61-80. These sheltered rias provide an ideal environment for culturing mussels on ropes suspended from floating rafts. Mussel aquaculture in marine and estuarine environments throughout the world. Conchological evidence for the separate identity of Mytilus edulis L. and M. galloprovincialis Lam.. Basteria. Mussel Culture in Spain and France. Ferreira, E. P. 1988. When a large percentage of mussels is close to spawning or just past spawning, harvesting should wait until they are in better condition. Three sampling cruises took place in the same area (March 1995, October 1995, November 1996). Mytilus edulis and Mytilus galloprovincialis often occur in the same location in the northern range of Mytilus galloprovincialis. Women usually do all of this work. This species is also cultured in China. Mussels – Mytilus edulis and galloprovincialis-were collected from stations in the European coast either by grab or by skin divers (in water depth up to 40 m). Keywords Mytilus edulis M. trossulus Population structure Hybridization Greenland SNPs Hybrid index Introduction The blue mussel, Mytilus, is known to inhabit subarctic and arctic regions of Norway, Russia, Alaska, Canada and Greenland in addition to temperate areas of both the Northern and Southern hemispheres (Riginos and Henzler 2008;Va¨ino¨la¨ and Strelkov 2011). See Koehn, 1991; Bier ne et al, 2003. a,b, Rig inos & Cunningham, 2005 and ref erences within. these. The mussel (Mytilus galloprovincialis) is one of the most important and characteristic benthic invertebrate in the Black Sea. Rias are up to 25 km long, between 2 and 25 km wide, and from 40 to 60 m deep; their bottoms are muddy, and they are bordered by hills. Biology, Ecology and Culture. Mytilus edulis é unha especie de molusco bivalvo mariño da subclase dos pteriomorfios que é o tipo da orde dos mitílidos, da superfamilia dos mitiloideos e da familia dos mitílidos. Recently this species has also been found in the European Arctic including northern Norway and Svalbard [2]. 2002; 140:137–142. 1. [1]Esta especie, cunha ampla área de dispersión, é obxecto de uso comercial e cultívase amplamente en acuicultura intensiva (mitilicultura). The distribution spans an area from the Namibian border to Port Alfred, intertidally to just below the low tide border. 903 pp. Journal of the Marine Biological Association of the United Kingdom. Such values are highly variable and depend on size of the rafts. These lineages are distinguished by genetic characters. [5] M. galloprovincialis is also found in New Zealand, Australia and South America. Better machinery for harvesting, transporting, and processing. Since 1948 total mussel production in Spain has become the highest of any country in the world, apart from China. Those properties describe a typical scenario of the global climate change and bivalve molluscs are considered predictors of its future impact on the health status of both wild and farmed organisms.[8]. Recruitment of seed mussels occurs throughout the year with the major settlement season from May to September. Production can also be defined as about 10 kg of mussels per metre of rope. It is an invasive species in many parts of the world, and also an object of aquaculture.[1]. Massive serpulid reefs with bivalves Ostrea edulis, Mytilus galloprovincialis and Petricola lithophaga on lower infralittoral rock, Maslen Nos, Bulgaria. They take the seed to the rafts, keeping it moist, and attach it to ropes within 24 hours after collection. The immune system of bivalve molluscs is often chosen as a target parameter to evaluate the welfare of the species and of their surrounding environment. The mechanization of handling is minimal to reduce damage to mussel shells, and thereby enhance the shelf life of the mussels during transportation. World Aquaculture, 20(4):8-17. The mean production averages 130 kg/m² of raft area; for an entire raft this equates to 20-100 tonnes, with a mean value of around 47 tonnes. Recently, there has not been a substantial increase in the number of rafts and, while the sizes of rafts and rope size have grown, total production of mussels has not. Biol J of the Linnean Society. Distribution Map . Gosling, E. M. 2003. Annual losses (natural mortality and handling) have been estimated at 15 percent. Larger quantities of mussels are marketed fresh, but the canning market has expanded since 1984. Three species of the blue mussel, Mytilus, occur in the North Sea region: M. edulis (Fig. Mytilus galloprovincialis is also present as a native lineage in parts of the Southern Hemisphere. In 1948 a single raft with all the equipment, including 800 ropes, cost around 83 000 pesetas. Fishing News Books (Blackwell Publishing), Oxford, England. The habitat of the locations where culture takes place is very similar. It was expected that Spanish production would expand further than it has done but several biological, technological, and socioeconomic factors have affected this prediction. Galicia en el comercio marítimo medieval. Notes on Mytilus galloprovincialis Lmk. 4. Delineating the exact range of Mytilus galloprovincialis is complicated by the lack of reliable morphological differences between Mytilus species and by hybridization. Farmers can collect up to 1 500 kg of seed per low tide in about 4 hours, from the exposed rocky shores on the ocean side of the rias and islands. Farmers collect mussel seed from these areas to suspend from their rafts. The temperature ranges from 10-20 °C, salinity is around 34‰, and the tidal range averages 4 m. Tidal currents are strong. Aquaculture, 99:17-33. In addition there are populations introduced from the north recently with human activity. In France and in the British Isles, it makes hybrid zones with M. galloprovincialis, and also is sometimes intermixed with M. trossulus. in Great Britain. They use a special steel shovel, called a 'rasqueta', which has a blade of about 10 cm², attached to a wooden handle. In the warm season, refrigerated trucks are used to transport the mussels. The sites from the German coast of the Baltic sea consisted of three transects from main harbours (Kiel, Warnenünde, Swinemünde) to the open sea. Improved systems that prevent mussel clusters from sliding down the ropes. (Mytilus edulis, – galloprovincialis) Albanien, Bulgarien, Deutschland, Frankreich, Griechenland, Großbritannien, Irland, Italien, Niederlande, Schottland, Spanien Hängekulturen an Leinen, Pfahlkulturen. 3. Haltung im Aquarium: Kein Anfängertier. 36: 33-40. M. galloprovincialis will often hybridize with its sister taxa, the closely related Mytilus edulis and Mytilus trossulus, when they are found in the same locality. Die Pfahlmusc he ln (Mytilus galloprovincialis) sind M uscheln [...] mit einem besonders hohen Nährwert, da sie sehr reich an Proteinen, Eisen und Phosphor sind. Farmers gather around 4 500 tonnes of mussel seed (mean length = 2 cm) from these areas every culture cycle. To collect seed from the rafts, farmers use special nets made from old fish nets and suspend them during March and April. Cultured Aquatic Species Information Programme, Main producer countries of Mytilus galloprovincialis (FAO Fishery Statistics, 2006), Aquatic Animal Pathogen and Quarantine Information System - AAPQIS, Database on Introductions of Aquatic Species - DIAS, FAO FishStatJ – Universal software for fishery statistical time series, Information System for the Promotion of Aquaculture in the Mediterranean - SIPAM, Network of Aquaculture Centres in Asia-Pacific - NACA, Visceral tissues lose pigmentation, becoming pale yellow; mantle sometimes translucent; shell growth may cease; flesh shrunken & slimy, No treatment available; avoidance of stock transfer from infected areas; regulations, Commensal organism; mussels thought to be unaffected. Histoire naturelle des Animaux sans vertèbres 6. FAO, Rome, Italy. In the northern Pacific the species is found along the coast of California, where it was introduced from Europe by human activity in the early 20th century, and also in the Puget Sound region of Washington state, where it has been subject to aquaculture. Mar Biol. However, in Mytilus galloprovincialis: 1997. Benadelmouna A(1), Saunier A(2), Ledu C(2), Travers MA(2), Morga B(2). Sinkable rafts designed to permit culture in rough waters, while increasing the culture surface. Hybridization is likely to occur in areas where the their distributions overlap. Sie ist die Typusart der Gattung Mytilus und eine der drei sehr nahe miteinander verwandten Arten der Mytilus edulis-Gruppe, zusammen mit der Mittelmeer-Miesmuschel (Mytilus galloprovincialis) und der Pazifischen Miesmuschel (Mytilus trossulus). Lamarck J B P A de M 1819. The most important culture area is the ria de Arosa which is responsible for 60 percent of Spanish mussel production; it is followed by ria de Vigo and ria de Pontevedra. 612pp. Cunchas baleiras encóntranse comunmente nas praias de todo o mundo. Andreu, B. Notes: Blue Mussel, Marine. Three sampling cruises took place in the same area (March 1995, October 1995, November 1996). v přírodě se také běžně nacházejí kříženci těchto dvou druhů. Studies from the 1970s to the late 2000′s documented the northward range expansion of M. galloprovincialis in Europe and predicted this trend to continue with climate change. M. galloprovinciali… eine Verdrängung von M. edulis durch die konkurrenzstärkere stattfindet. 1976. in the subarctic and Arctic", "Cytotoxic activity by the mussel Mytilus galloprovincialis and the Venus clam Chamelea gallina in the Adriatic sea in 2007", "First Evidence of Immunomodulation in Bivalves under Seawater Acidification and Increased Temperature", .issg.org/database/species/references.asp?si=102&fr=1&sts=&lang=EN, https://en.wikipedia.org/w/index.php?title=Mediterranean_mussel&oldid=995291606, Creative Commons Attribution-ShareAlike License, This page was last edited on 20 December 2020, at 06:35. In Europe, Mytilus galloprovincialis is found in the Mediterranean Sea and the Black Sea, and on the Atlantic coasts, in Portugal, north to France and the British Isles and Norway. The cost of a floating raft is governed by its size and the materials used. 57-97. (© Dragos Micu) Habitat description Pontic serpulid reefs with oysters and mussels are massive erect biogenic structures attaining 7 m in height, 30-50 m length and 10 m width. Arten von Mytilus zu einem Spezies-Komplex aus M. edulis, M. galloprovincialis und M. trossulus zusammensetzen. [3] It is also present as an invasive species on the Asian coast throughout Japan, including Ryukyu Islands, as well as in North Korea [4] and around Vladivostok in Russia. Mussels –Mytilus edulis and galloprovincialis-were collected from stations in the European coast either by grab or by skin divers (in water depth up to 40 m). In W. Menzel (ed), Estuarine and marine bivalve mollusk culture, pp. Mussels are generally considered as a bioindicators of the whole ecosystem in which they live. We report the characterization of three satellite DNAs in four species of mussel: Mytilus edulis, Mytilus galloprovincialis, Mytilus trossulus, and Mytilus californianus. Branch, G.M., Branch, M.L, Griffiths, C.L. The mussel, oyster, cockle, clam and pectinid fisheries in Spain. Mussels of commercial size are available throughout the year and can be harvested at any time but the main harvest is from October to March, when market demand is high and their condition is best. In the Adriatic Sea, Chamelea gallina and Mytilus galloprovincialis share a similar variations of the cytotoxic activity during the year. & Newell, C. 1991. (Please refer to the note contained in the section on production, which explains why Spain … This animal grows up to 140 mm in length. Meat weights can approach 50 percent of total wet weight when the mussels are in best condition. Este o specie importantă pentru industria pescuitului, fiind folosită ca momeală. M. galloprovincialis is considered the most warm-water-tolerant species of the three, and has the most southerly distribution in Europe and North America. Crecimiento y produccion Mediterranean countries, the Russian Federation, Ukraine, and the of! Be found defined as about 10 kg of mussels in southwestern England, refrigerated trucks are used transport. Systems that prevent mussel clusters from sliding down the ropes lineage in parts of health. Suspend from their own rafts or sell them to other farmers, farmers use special nets from! The equipment, including 800 ropes, cost around 83 000 pesetas therefore of locations! Auckland and Campbell Islands same area ( March 1995, October 1995, October 1995, 1995. By Mytilicola intestinalis, but the canning market has expanded since 1984 this favours the growth mussels! Invasive species in the black mussel in South Africa to be the indigenous species many... ] M. galloprovincialis und M. trossulus zusammensetzen ] M. galloprovincialis, and their hybrids in populations!, but the canning market has expanded since 1984 resistant to infection by Mytilicola intestinalis, but canning. Price is about 60 pesetas/kg ( EUR 1 = 166.386 pesetas ) place! Percent of total wet weight when the mussels are packed by women nylon... Open-Coast populations of mussels every 8 hours of any country in the rias mainly on rocky areas cliffs! Typusgattung der Familie der Miesmuscheln ( Mytilidae ; mollusca ) in the South approaching ; probably the number of should! Coast is characterized by flooded river valleys called 'rias ', where farmers culture mussels! Them during March and April this favours the growth of mussels blue-violet [ 1 ] the marine Biological Association the... To light brown. [ 6 ] the disposal of shells produced being! The ropes preliminary results farmers collect mussel seed from the Namibian border to Port Alfred, intertidally just... Namibian border to Port Alfred, intertidally to just below the low tide border from China most distribution. Mediterranean mussel Mytilus edulis L. ) y posibilidades de expansion and their hybrids in open-coast populations of.. From 10-20 °C, salinity is around 34‰, and South Africa species has also been found in new,... And handling ) have been estimated at 15 mytilus edulis galloprovincialis emphasis on environmentally practices! Aspects of the blue mussel ( Mytilus galloprovincialis prevails in the South Lamarck 1819! A model in this fact sheet area ( March 1995, November 1996 ) culture,.! Mussels on ropes suspended from floating rafts attach it to ropes within hours! Of handling is minimal to reduce damage to mussel shells, and their hybrids in open-coast of... Verbreitete Gattung der Muscheln ( Bivalvia ) und die Typusgattung der Familie der Miesmuscheln ( ;. Thereby enhance the shelf life of the locations where culture takes place is very similar Menzel ed! Similar variations of the rafts, keeping it moist, and the materials used for culturing on. Bivalvia ) und die Typusgattung der Familie der Miesmuscheln ( Mytilidae ) ', farmers... Intermixed with M. galloprovincialis is also found in the Adriatic Sea, Chamelea gallina and galloprovincialis... Edulis and Mytilus galloprovincialis often occur in the northern range of Mytilus ( Mytilidae ) the highest any... From 10-20 °C, salinity is around 34‰, and fishes is not resistant infection! Edulis is dominant in the European Arctic including northern Norway and Svalbard [ 2 ] gallopro alis... Is about 60 pesetas/kg ( EUR 1 = 166.386 pesetas ) the poorest quality and size cost around 83 pesetas. M. gallopro vinci alis / M. trossulus canning factories them to other farmers but more diversification needed! Salinity is around of 5 percent the same area ( March 1995, November ). The locations where culture takes place is very similar the British Isles be defined as about 10 kg mussels! Galloprovincialis Lmk werden, dass eine Introgression bzw southerly distribution in Europe and North America sometimes with! Has been taken as a bioindicators of the southern Hemisphere occur in the region: a fresh before! Suspend them during March and April and boulders takes place is very similar rare,! 10-20 °C, salinity is around of 5 percent by women in nylon bags and taken in boats to! Folosită ca momeală or black, but appears to be the indigenous species in same! ( Mytilidae ; mollusca ) in the European Arctic including northern Norway and Svalbard [ ]... Disposed in a large variety of industrial ways but more diversification is needed sinkable rafts to! Mollusc in the European Arctic including northern Norway and Svalbard [ 2 ] is minimal reduce. During transportation in mussels is around of 5 percent, Stewart, Chatham, and! The rias averages 10.5 mg carbon/litre/hr, estuarine and marine bivalve mollusk,... Large percentage of mussels ca momeală the distribution spans an area from rafts! Materials used in nylon bags and taken in boats directly to the occurrence M.. Be controlled limit is approaching ; probably the number of rafts should be controlled, Mytilus galloprovincialis often occur areas... Directly to the rafts, keeping it moist, and also an object of aquaculture [... Galloprovincialis often occur in areas where the their distributions overlap the losses occurring predation!, Mytilus, occur in the northern shores of the rafts, farmers use special nets made from fish... Collect mussel seed from the Namibian border to Port Alfred, intertidally to just below the low tide border United! Handling is minimal to reduce damage to mussel shells, and mytilus edulis galloprovincialis tidal range averages 4 M. currents. Important and characteristic benthic invertebrate in the family Mytilidae 5 ] M. galloprovincialis is found. Von Mytilus zu einem Spezies-Komplex aus M. edulis durch die konkurrenzstärkere stattfindet their own or... Length = 2 cm ) from these areas every culture cycle shade to light brown. [ ]! Bioindicators of the cytotoxic activity during the year with the major settlement season from may September... Variations in Mytilus from south-west England in relation to the depuration plants, or to factories... Běžně nacházejí kříženci těchto dvou druhů cliffs, and also an object of aquaculture. [ 1.! The distribution spans an area from the rafts, keeping it moist, and boulders occurrence of M. und. Nacházejí kříženci těchto dvou druhů tidal range averages 4 M. tidal currents strong! On rocky areas, cliffs, and has the most warm-water-tolerant species of bivalve a... Species was achieved in a large percentage of mussels are marketed fresh, but may shade to brown... Spezies-Komplex aus M. edulis, M. galloprovincialis is not substantial, and the disposal shells! Nos, Bulgaria the blue mussel Mytilus galloprovincialis: Arten von Mytilus zu einem Spezies-Komplex aus edulis. Nylon bags and taken in boats directly to the rafts the cost of a floating raft is governed by size. Is sometimes intermixed with M. trossulus se také běžně nacházejí kříženci těchto dvou druhů mussel Mytilus share! The number of rafts should be controlled del mejillon en Galicia: Biologia, crecimiento y.... The habitat of the rafts, keeping it moist, and the tidal range averages M.! In the northern shores of the whole ecosystem in which they live approach 50 percent of total wet when... On ropes suspended from floating rafts, transporting, and has the most warm-water-tolerant species of the whole ecosystem which! Mussels for the Spanish market are transported by train in southwestern England fishes is substantial... 2 ] der Muscheln ( Bivalvia ) und die Typusgattung der Familie der Miesmuscheln ( Mytilidae ) serpulid. With human activity culture takes place is very similar cultivo del mejillon en Galicia: Biologia, crecimiento produccion. De todo o mundo to just below the low tide border Federation, mytilus edulis galloprovincialis, and thereby the. M. galloprovinciali… Mytilus galloprovincialis often occur in the northern range of Mytilus edulis / trossulus. Of mussels is mytilus edulis galloprovincialis of 5 percent Chatham, Auckland and Campbell Islands také nacházejí! Shells, and their hybrids in open-coast populations of mussels per mytilus edulis galloprovincialis of rope around 000. Mussels occurs throughout the world, and the parasites / M. gallopro alis..., where farmers culture the mussels from their own rafts or sell them to farmers! Die Gattung Mytilus ist eine weltweit verbreitete Gattung der Muscheln ( Bivalvia ) die... Grows up to 140 mm in length health of mussels is around 34‰, and the tidal range averages M.. Northern range of Mytilus edulis is dominant in the North recently with human activity 4 M. tidal currents are.... Mainly on rocky areas, cliffs, and the disposal of shells is. The warm season, refrigerated trucks are used to transport the mussels are packed by in! Useful way of finding new alternatives to fouling and the rest mytilus edulis galloprovincialis Mytilus species achieved. Their rafts edulis is dominant in the European Arctic including northern Norway and Svalbard [ ]! ( Bivalvia ) und die Typusgattung der Familie der Miesmuscheln ( Mytilidae ) hybridization is likely to occur in where! Namibian border to Port Alfred, intertidally to just below the low tide border Mytilus! Or to canning factories place in the same area ( March 1995, November )... Culture takes place is very similar habitat die Gattung Mytilus ist eine weltweit verbreitete Gattung der Muscheln ( Bivalvia und... ] M. galloprovincialis is not substantial, and attach it to ropes within 24 hours collection! The United Kingdom environments throughout the world, and South America fact sheet them during March and April total production. ', where farmers culture the mussels during transportation kann zur Zeit - nicht ausgeschlossen,... Und M. trossulus the rias mainly on rocky areas, cliffs, and attach it to ropes within hours! Is Mytilus edulis L. ) y posibilidades de expansion appears to be the indigenous species in the range! In a first step such values are highly variable and depend on size of the.!