{"id":219,"date":"2016-01-14T15:56:26","date_gmt":"2016-01-14T15:56:26","guid":{"rendered":"http:\/\/www.efolio.soton.ac.uk\/blog\/discoveroceanography\/?page_id=219"},"modified":"2019-06-08T12:24:37","modified_gmt":"2019-06-08T11:24:37","slug":"secchi-disk","status":"publish","type":"page","link":"https:\/\/generic.wordpress.soton.ac.uk\/discoveroceanography\/for-teachers\/workbook-2\/secchi-disk\/","title":{"rendered":"Secchi disk"},"content":{"rendered":"<p><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-275  alignright\" src=\"http:\/\/generic.wordpress.soton.ac.uk\/discoveroceanography\/wp-content\/uploads\/sites\/335\/2016\/01\/secci-2-179x300.jpg\" alt=\"\" width=\"86\" height=\"144\" srcset=\"https:\/\/generic.wordpress.soton.ac.uk\/discoveroceanography\/wp-content\/uploads\/sites\/335\/2016\/01\/secci-2-179x300.jpg 179w, https:\/\/generic.wordpress.soton.ac.uk\/discoveroceanography\/wp-content\/uploads\/sites\/335\/2016\/01\/secci-2.jpg 468w\" sizes=\"auto, (max-width: 86px) 100vw, 86px\" \/>Knowing how far into the water column the light penetrates and how it behaves within the water column is very important information to marine scientists. The Photic Zone is the upper section of the water column, where there is sufficient light to allow photosynthesis to occur. Photosynthesis is one of the most important processes within the marine environment as this is how <span class='tooltipsall tooltipsincontent classtoolTips12'>Phytoplankton<\/span> gain the energy they need to reproduce. <span class='tooltipsall tooltipsincontent classtoolTips12'>Phytoplankton<\/span> is the basis of the marine food web, and without it the marine food web would collapse.<\/p>\n<p>The Secchi Disk is an instrument used to measure how far light can penetrate into\u00a0water. It is a simple piece of equipment, with no moving parts or electronics, and provides consistently accurate results. For this reason it has been in continuous use since its development, in 1866, by Pietro Angelo Secchi.\u00a0The disk is simply lowered over the side of the vessel and down into the water until you can\u2019t see it any more.<\/p>\n<p>The <span class='tooltipsall tooltipsincontent classtoolTips72'>Depth<\/span> at which it has disappeared is known as the Secchi <span class='tooltipsall tooltipsincontent classtoolTips72'>Depth<\/span>. Various physical quantities can be obtained mathematically from the Secchi <span class='tooltipsall tooltipsincontent classtoolTips72'>Depth<\/span>, including the light penetration <span class='tooltipsall tooltipsincontent classtoolTips72'>Depth<\/span>, which is 3 times the Secchi <span class='tooltipsall tooltipsincontent classtoolTips72'>Depth<\/span>.<\/p>\n<p>The light penetration <span class='tooltipsall tooltipsincontent classtoolTips72'>Depth<\/span> obtained by Secchi Disc very closely approximates to the 1% light level <span class='tooltipsall tooltipsincontent classtoolTips72'>Depth<\/span>, which is the water <span class='tooltipsall tooltipsincontent classtoolTips72'>Depth<\/span> at which the light intensity has fallen to 1 % of the surface level of illumination. This is important because it is the maximum <span class='tooltipsall tooltipsincontent classtoolTips72'>Depth<\/span> at which there is generally sufficient light for plant life to photosynthesise.<\/p>\n<div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-14\" class=\"h5p-iframe\" data-content-id=\"14\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\"><\/iframe><\/div>\n<p><strong>Why not have a go at making your own Secchi Disk?<\/strong><\/p>\n<p>The reason we still use the Secchi Disk today, some 144 years after it was first invented, is that it is a very simple piece of scientific equipment. With no moving parts or requirement for electricity, and it can be easily and quickly made.<\/p>\n<div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-25\" class=\"h5p-iframe\" data-content-id=\"25\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\"><\/iframe><\/div>\n<script type=\"text\/javascript\"> toolTips('.classtoolTips0','The variable that is changed or controlled in a scientific experiment to test the effects on\u00a0the dependent variable.'); <\/script><script type=\"text\/javascript\"> toolTips('.classtoolTips12','Plankton consisting of microscopic plants.'); <\/script><script type=\"text\/javascript\"> toolTips('.classtoolTips20','The branch of science that deals with the physical and biological properties and phenomena of the sea.'); <\/script><script type=\"text\/javascript\"> toolTips('.classtoolTips71','A very large expanse of sea, in particular each of the main areas into which the sea is divided geographically.'); <\/script><script type=\"text\/javascript\"> toolTips('.classtoolTips72','The distance from the top or surface to the bottom of something.'); <\/script>","protected":false},"excerpt":{"rendered":"<p>Knowing how far into the water column the light penetrates and how it behaves within the water column is very important information to marine scientists. The Photic Zone is the upper section of the water column, where there is sufficient light to allow photosynthesis to occur. Photosynthesis is one of &hellip;<\/p>\n","protected":false},"author":3738,"featured_media":1480,"parent":114,"menu_order":3,"comment_status":"closed","ping_status":"open","template":"","meta":{"footnotes":""},"class_list":["post-219","page","type-page","status-publish","has-post-thumbnail","hentry"],"jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/generic.wordpress.soton.ac.uk\/discoveroceanography\/wp-json\/wp\/v2\/pages\/219","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/generic.wordpress.soton.ac.uk\/discoveroceanography\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/generic.wordpress.soton.ac.uk\/discoveroceanography\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/generic.wordpress.soton.ac.uk\/discoveroceanography\/wp-json\/wp\/v2\/users\/3738"}],"replies":[{"embeddable":true,"href":"https:\/\/generic.wordpress.soton.ac.uk\/discoveroceanography\/wp-json\/wp\/v2\/comments?post=219"}],"version-history":[{"count":3,"href":"https:\/\/generic.wordpress.soton.ac.uk\/discoveroceanography\/wp-json\/wp\/v2\/pages\/219\/revisions"}],"predecessor-version":[{"id":1662,"href":"https:\/\/generic.wordpress.soton.ac.uk\/discoveroceanography\/wp-json\/wp\/v2\/pages\/219\/revisions\/1662"}],"up":[{"embeddable":true,"href":"https:\/\/generic.wordpress.soton.ac.uk\/discoveroceanography\/wp-json\/wp\/v2\/pages\/114"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/generic.wordpress.soton.ac.uk\/discoveroceanography\/wp-json\/wp\/v2\/media\/1480"}],"wp:attachment":[{"href":"https:\/\/generic.wordpress.soton.ac.uk\/discoveroceanography\/wp-json\/wp\/v2\/media?parent=219"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}