{"id":641,"date":"2014-10-30T13:45:59","date_gmt":"2014-10-30T12:45:59","guid":{"rendered":"http:\/\/www.oceanblogs.org\/kosmos2014gc\/?p=641"},"modified":"2014-10-30T15:03:06","modified_gmt":"2014-10-30T14:03:06","slug":"planktonparadise","status":"publish","type":"post","link":"https:\/\/www.oceanblogs.org\/kosmos2014gc\/2014\/10\/30\/planktonparadise\/","title":{"rendered":"Turning an ocean desert into plankton paradise"},"content":{"rendered":"

It may seem like the perfect sea to swimmers, snorklers, and divers – crystal clear, turquoise water with an underwater visibility of 30 metres and more. Among marine scientists this is often referred to as an ocean desert. The concentrations of plant nutrients in these waters are so low, that it takes special instruments and a highly experienced analyst to detect them. It is the scarcity of these plant nutrients that keeps life at the edge in the waters, the number of plankton organisms low and the water crystal clear. During the first part of our experiment, these were also the conditions in our mesocosms.<\/p>\n

But occasionally parts of these ocean deserts are turned into plankton paradise. Unlike in real deserts, it\u2019s not the rainwater from above but the deep water from below that makes life flourish. In much of the tropical and subtropical open ocean, these events are driven by swirling currents, so-called eddies, which can push nutrient-rich deep waters into the sunlit surface layer. These eddies are also common features in the wake of islands and are a well-known phenomenon south of the Canaries.<\/p>\n

\"Deep

Loading of the deep-water collector on the chartered vessel SEPCAN IV<\/p><\/div>\n

To simulate such an event in our mesocosms, we collected 80,000 litres of deep water at 650 m depth five nautical miles off-shore in a giant plastic balloon, which was then towed to our mesocosm playground. During the night from October 25 to 26, the deep water was then distributed into our nine mesocosms, making sure that all mesocosms ended up with precisely the same deep-water mixing ratio. Doing this over night avoided nutrients being consumed by the nutrient-starved phytoplankton before we could even measure their initial concentrations. It didn\u2019t take long for the phytoplankton to respond – a couple of days after deep-water addition the plankton party is in full swing. To capture the rapid changes, we decided to further increase our sampling frequency \u2013 ignoring for the time being that our own batteries are gradually running down.<\/p>\n

\"Deep<\/a>

Deep-water collector secured by divers before towing to the mesocosm study site<\/p><\/div>\n

Now we are eagerly watching the party in our enclosed biospheres and hope to learn more about the rules of switching from ocean desert to plankton paradise. Who can make the best use of the nutrient boon? How efficient is the plentiful food transferred up the food web? What are the consequences for elemental and energy fluxes und air-sea exchange? And what are the impacts of ocean acidification on all these processes?<\/p>\n

 <\/p>\n

Wie ozeanische W\u00fcsten sich in ein Planktonparadies verwandeln<\/strong><\/p>\n

\"Deep<\/a>

A giant ballon in motion – like a grey way plowing its way through the ocean<\/p><\/div>\n

F\u00fcr Schwimmer, Schnorchler und Taucher mag es wie der perfekte Ozean anmuten \u2013 kristallklares, t\u00fcrkisblaues Wasser mit einer Unterwassersicht von 30 Metern und mehr. Unter Meereswissenschaftlern wird es oft als ozeanische W\u00fcste bezeichnet. Die Konzentration an Pflanzenn\u00e4hrstoffen in diesen Gew\u00e4ssern ist so niedrig, dass es spezieller Messinstrumente und erfahrener Analysten bedarf, um sie nachzuweisen. Dieser Mangel an N\u00e4hrstoffen h\u00e4lt das Leben kurz , die Zahl der Planktonorganismen gering und das Wasser kristallklar. Dies waren die Bedingungen in unseren Mesokosmen w\u00e4hrend Teil 1 unserer Studie.<\/p>\n

Hin und wieder verwandeln sich Teile dieser ozeanischen W\u00fcsten allerdings in ein Planktonparadies. Im Gegensatz zu tats\u00e4chlichen W\u00fcsten ist es nicht das herabregnende Wasser von oben, sondern Wasser aus der Tiefe des Ozeans, welches das Leben erbl\u00fchen l\u00e4sst. In gro\u00dfen Teilen der tropischen und subtropischen Meere werden solche Ereignisse durch ozeanische Wirbel, sogenannte Eddies, ausgel\u00f6st, die n\u00e4hrstoffreiches Wasser aus der Tiefe in die lichtdurchflutete Oberfl\u00e4chenschicht transportieren. Solche Eddies treten h\u00e4ufig im Str\u00f6mungsschatten von Inseln auf und werden auch s\u00fcdlich der Kanaren permanent gebildet.<\/p>\n

\"Deep<\/a>

Deep-water addition – an all-nighter for the KOSMOS team<\/p><\/div>\n

Um ein solches Ereignis auch in unseren Mesokosmen zu simulieren, haben wir f\u00fcnf Meilen vor der K\u00fcste in 650 Metern Tiefe 80.000 Liter Tiefenwasser in einen riesigen Plastikballon gepumpt und diesen dann zu unserer Mesokosmen-Spielwiese gezogen. In der Nacht vom 25. auf den 26. Oktober haben wir das Tiefenwasser dann auf die neun Mesokosmen verteilt. Ganz wichtig: alle Mesoksomen mussten exakt das gleiche Mischungsverh\u00e4ltnis bekommen. Und alles musste in einer Nacht \u00fcber die B\u00fchne gehen, um die Ausgangskonzentrationen der N\u00e4hrstoffe bestimmen zu k\u00f6nnen, bevor das lichtabh\u00e4ngige Phytoplankton sie aufnehmen konnte. Tats\u00e4chlich lie\u00df die Reaktion des Phytoplanktons nicht lange auf sich warten. Jetzt ist die Planktonparty in vollem Gange. Weil bei im warmen Wasser und bei den hohen Lichtintensit\u00e4ten alles sehr schnell geht, haben wir unser Mess- und Probenahmeintervall noch einmal verk\u00fcrzt – auch wenn es t\u00fcchtig an den Kr\u00e4ften zehrt.<\/p>\n

Gespannt schauen wir dem bunten Treiben in unseren eingeschlossenen Welten zu und hoffen, so mehr \u00fcber den Wechsel von ozeanischen W\u00fcsten zu Planktonparadiesen zu lernen. Wer kann den N\u00e4hrstoffsegen am besten nutzen? Wie effizient wird das reichhaltige Futterangebot im Nahrungsnetz weitergereicht? Was bedeutet dies f\u00fcr die Stoff- und Energiefl\u00fcsse und den Austausch zwischen Ozean und Atmosph\u00e4re? Und welchen Einfluss hat Ozeanversauerung auf all diese Prozesse?<\/p>\n","protected":false},"excerpt":{"rendered":"

It may seem like the perfect sea to swimmers, snorklers, and divers – crystal clear, turquoise water with an underwater visibility of 30 metres and more. Among marine scientists this is often referred to as an ocean desert. The concentrations of plant nutrients in these waters are so low, that it takes special instruments and […]<\/p>\n","protected":false},"author":43,"featured_media":646,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[],"class_list":["post-641","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-uncategorized"],"_links":{"self":[{"href":"https:\/\/www.oceanblogs.org\/kosmos2014gc\/wp-json\/wp\/v2\/posts\/641","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.oceanblogs.org\/kosmos2014gc\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.oceanblogs.org\/kosmos2014gc\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.oceanblogs.org\/kosmos2014gc\/wp-json\/wp\/v2\/users\/43"}],"replies":[{"embeddable":true,"href":"https:\/\/www.oceanblogs.org\/kosmos2014gc\/wp-json\/wp\/v2\/comments?post=641"}],"version-history":[{"count":5,"href":"https:\/\/www.oceanblogs.org\/kosmos2014gc\/wp-json\/wp\/v2\/posts\/641\/revisions"}],"predecessor-version":[{"id":654,"href":"https:\/\/www.oceanblogs.org\/kosmos2014gc\/wp-json\/wp\/v2\/posts\/641\/revisions\/654"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.oceanblogs.org\/kosmos2014gc\/wp-json\/wp\/v2\/media\/646"}],"wp:attachment":[{"href":"https:\/\/www.oceanblogs.org\/kosmos2014gc\/wp-json\/wp\/v2\/media?parent=641"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.oceanblogs.org\/kosmos2014gc\/wp-json\/wp\/v2\/categories?post=641"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.oceanblogs.org\/kosmos2014gc\/wp-json\/wp\/v2\/tags?post=641"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}