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Dieren en planten

Water en land

Mens en Milieu

, NIOZ/Ecomare

Plankton calender

One-celled algae are also called phytoplankton, phyto referring to plants and plankton referring to free-floating plants or animals. Not all plankton live at the same time of the year. And not all the plankton that you see in January of one year will be seen necessarily in January of the next year. However, there is a sequence of when they do appear so it is possible to make a kind of plankton calendar. Scientists at the Royal Dutch Marine Institute for Sea Research (NIOZ) did just that†in 2008†for plankton found in the Marsdiep, the channel between Texel and Den Helder. The following 12 paragraphs are a reproduction of that calendar.

  • January
    , NIOZ

    Pediastrum: Dit is een zoetwater groenalg uit het IJsselmeer. Via spuisluizen is het in de Waddenzee terechtgekomen.

  • February
    , NIOZ

    Odontella aurita: centric diatom. One of the first species to multiply in the spring.

  • March
    , NIOZ

    Thalassionema pseudonitzschioides: staff-shaped diatom. Each leg of the half-star consists of 2 diatoms.

  • April
    , NIOZ

    Rhizosolenia hebetata f. semispina: diatom that makes chain-shaped colonies. Photo made during an algae blossom. A blossom in this case means massive appearance.

  • May
    , NIOZ

    Phaeocystis globosa: foamy algae, flagellate. Each bright spot is one flagellate. Each circle is a colony. This is the most numerous algae species in the Marsdiep (80 million per liter seawater).

  • June
    , NIOZ

    Noctiluca scintillans: dinoflagellate. Extremely large and transparent. When touched, it produces a spark to scare away its enemies.

  • July
    , NIOZ

    Guinardia delicatula: centric diatom

  • August
    , NIOZ

    Guinardia striata: centric diatom. Makes circle-shaped chains.

  • September
    , NIOZ

    Chaetoceros socialis: diatom. Young colonies are arranged in an orderly manner. The older the colony, the more chaotic the arrangement.

  • October
    , NIOZ

    Coscinodiscus wailesii: largest diatom found in the Marsdiep and North Sea (1/3 mm -1/2 mm in diameter). First seen in European waters in 1977. Comes from the Indian or Pacific Ocean. Probably arrived via ballast water or oyster import.

  • November
    , NIOZ

    Bacteriastrum hyalinum: centric diatom. The 3de, 5th and 6th spores from the left are in the process of preparing for the winter by forming resting spores. By making round thick outer layers, they become heavier and sink to the bottom. Resting spores cannot mulitply.

  • December

    Odontella sinensis: centric diatom