Daya daga cikin ƙarami sanannun tekuna shine Tekun Arewa. Jiki ne na ruwan gishiri da aka ɗauka a matsayin teku mara iyaka a cikin Tekun Atlantika. Tana can yamma da Nahiyar Turai tsakanin Burtaniya, Jamus, Faransa, Belgium, Netherlands, Denmark, Sweden da Norway, tana da fasali mai kusurwa huɗu wanda ke ɗaukar kimanin yanki na 570,000 km2 da ƙarar 54,000 -94,000 km3.
A cikin wannan labarin zamu gaya muku game da duk halaye, samuwar, bambancin halittu da barazanar Tekun Arewa.
Babban fasali
Babban teku ne na Tekun Atlantika wanda tsawonsa duka An kiyasta shi kusan kilomita 960 kuma mafi girman ɓangarensa ya kai kilomita 580. Ruwa ne wanda ya haɗu da sauran Tekun Atlantika ta hanyar Pas de Calais da Tashar Ingilishi, kuma tare da Baltic ta hanyar Skagerrak Strait da kuma Kattegat Strait na gaba. A cikin wannan teku akwai tsibirai da yawa kamar su Frisian Islands, Farne, sauran ƙananan tsibirai da tsibirai kusa da bakin teku.
Kogunan da galibi ke ciyar da wannan teku sune Rhine, da Gloma, da Elbe, da Weser, da Drammen, da Ätran, da Thames, da Trent da Ems. Kasancewarsa ɗan ƙaramin teku mai shekaru yana da ƙasa. A ɓangaren arewacin yana da ɗan zurfin zurfin amma kawai ya isa wasu yankuna masu zurfin mita 90. Matsakaicin zurfin da aka kiyasta shine mita 700 kuma ɓangaren arewa yana cikin yankin Norway. Ruwa ne ko ƙarancin yanayin zafi wanda wani lokacin yakan daskare. Wani lokaci ana ganin tumakin kankara suna shawagi a saman.
Abu mafi dacewa shi ne cewa a lokacin hunturu ruwan saman Tekun Arewa ya kai digiri 6 a kan matsakaici, yayin da a lokacin rani zafin yakan hau zuwa digiri 17. Mafi yawan kwararar ruwan gishiri yana zuwa ne daga Tekun Atlantika kuma mafi ƙarancin zazzabi kuma mafi ƙarancin ruwan gishirin yana fitowa daga yankin Baltic. Kamar yadda ake tsammani, yankunan da ba su da gishiri a wannan teku sune waɗanda suke a yankunan da ke kusa da bakin kogunan.
Yankin Tekun Arewa ya bambanta dangane da yankin da muke. Musamman a arewacin yankin da kuma gefen gabar fjords na Norway, tsaunuka, bakin teku masu ƙanƙanci, kwari da rairayin bakin teku tare da dunes sanduna gama gari ne. Duk waɗannan tsarukan halittu suna cikin yankin bakin ruwa na ƙasar Norway. Koyaya, a cikin yankunan gabas da yamma wasu tare da taimako na yau da kullun kuma wasu yankuna masu tsayi sun bambanta.
Tsarin arewacin teku
Kamar yadda muka ambata a baya, yana daya daga cikin mafi karancin shekaru a duniya. Yana da kimanin shekaru 3.000 ne kawai a yankin bakin teku. Ya fara girma daga rabuwar babbar nahiyar Pangea tunda wannan rabuwar tana bude manyan kasa da aka wadata ta bakin kogunan da aka ambata a sama. Farkon Zamanin Cenozoic, manyan yankuna suka rabu kuma Tekun Atlantika ya riga ya kafa.
Ana iya cewa wannan tekun an ƙirƙira shi zuwa ɓangarori ta wasu canje-canje waɗanda suka faru a matakin ilimin ƙasa. A lokacin Triassic y Jurassic an samar da gidaje masu yawa da kurakurai waɗanda suka bar duk yankin inda a yau manyan yankuna ke cikin cikakken tsari. Wannan yasa wasu yankuna suna da ruwa. A wannan lokacin samuwar ƙwanƙolin ƙasa ya tashi kuma Tsibirin Burtaniya bai kafa ba.
Daga baya a lokacin zamanin Oligocene, tsakiya da yamma na nahiyar Turai sun riga sun sami ruwa. Kusan dukkanin ruwan da ya raba Tekun Tethys ya bayyana. Kusan shekaru miliyan 2.6 da suka wuce, a lokacin Pliocene Tekun Arewacin ya riga ya kasance kudu da Bankin Dogger, ya kasance wani ɓangare na Turai kuma Rhine ya wofinta cikin ruwan gishirinta. Saboda bambancin shekarun kankara wadanda suka faru a cikin lokaci, shimfidar kankara suna ta kirkira suna ja baya a lokacin Pleistocene.
Shekaru 8.000 da suka wuce ne kankara ta ɓace gaba ɗaya kuma matakin teku ya fara tashi. Saboda gudummawar ruwa daga koguna da bacewar kankara, tekun na iya fara zama gaba daya. Bugu da kari, hauhawar matakin teku ya sa gadar kasa da ke tsakanin Burtaniya da Faransa ta yi ambaliyar sannan aka hade Tashar Ingilishi da sharrin Arewa.
Bambance-bambancen halittu na Tekun Arewa
Kamar yadda ake tsammani, wannan tekun yana da wadataccen halittu masu yawa kuma ba mazauni ne kawai na dabbobi da yawa ba, har ma da wurin ziyarar dabbobi masu ƙaura. Mun sami adadi mai yawa na dabbobi masu shayarwa kamar hatimin gama gari, hatimin kofato, babban amintacce, hatimin ringi, dabbar whale dama da sauran nau'ikan dabbobi masu shayarwa. Amma kifi, muna da nau’uka daban-daban sama da 230 daga cikinsu muna samun kifi, kifin kama, kifi, kifi da ciyawa. Duk waɗannan nau'ikan nau'ikan kifayen suna da ni'ima ta yawancin ɗimbin abubuwan gina jiki waɗanda rafuka ke bayarwa da kuma kasancewar plankton.
Hakanan muna samun adadi mai yawa na tsarin halittu masu dacewa waɗanda ke ba da cikakkun wuraren zama don gida da wurin zama na wasu tsuntsayen ruwa da ƙaura. Waɗannan ɗakunan ilimin sun dace da mafaka da yawa. Daga cikin tsuntsayen teku wadanda suke samun mafaka a cikin wadannan masanan da muke dasu loons, auks, puffins, terns da boreal fulmars. A zamanin da an san Tekun Arewa sosai don bambancin halittu fiye da yadda yake a yau. A cikin ƙarnuka da yawa a cikin wannan yanki ya ragu sosai.
Barazana
Dan Adam yana nan a cikin mafi yawan barazanar dukkan tekuna da tekunan duniya. Kamar yadda zaku iya tsammani, wannan shari'ar ba ta da bambanci. Sakamakon gano albarkatun mai da iskar gas wanda ke wanzuwa a ƙarƙashin wannan tekun, Tekun Arewa ya kasance abin da ake taƙama da cinikayyar kasuwanci. Duk ƙasashen da ke kewayen Tekun Arewa suna ta yin amfani da albarkatun mai da burbushin halittu kuma yankuna suna wadatar da hakar yashi da tsakuwa.
Saboda wadannan ayyukanda suka shafi tattalin arziki, rabe-raben halittun ruwa ya ragu sakamakon baiwa gabatar da injina cikin mahalli na asali da yawan gurɓata da kamun kifi. Wasu nau'in sun bace, kamar su flamingos da katuwar auk. Wannan nau'in na ƙarshe ya ɓace ko'ina cikin Duniya.
Ina fatan cewa tare da wannan bayanin zaku iya ƙarin koyo game da Tekun Arewa da halayenta.