Marine Life / Science

Springtime in the Estuary!

Spring is springing (finally!) here on the NC coastline and I feel like there has been a complete re-birth. People are back in town, flowers are blooming, plants are turning green again, crops are being planted, and more and more people are getting back on the water. Signs of spring are everywhere on land, which made me wonder, are there signs of spring in the water too?!

And there are! Just like on land, things in the water are starting to heat up. This warming of the water not only leads to an awakening of boats and people on the water, but also an awakening of tiny plant-like organisms called phytoplankton as well. These tiny guys live in the water column, and just like plants, photosynthesize. And like plants, as the days get warmer, the phytoplankton become happier!

Not only do phytoplankton like the warmer temperatures associated with spring, but, more importantly, they like the increase in light associated with the longer daylight hours and the shorter distance between the sun and the northern hemisphere. Just like the plants start to get greener in the spring, phytoplankton in the estuaries can start to grow better too.


Phytoplankton (like these guys, seen under a microscope) enjoy the warmer weather and increased rainfall associated with spring. Image from here.

But that’s not all! Remember the saying ‘April showers bring May flowers’? This can also be true for phytoplankton in estuaries. All those April showers flush more nutrients into the estuary.  Phytoplankton need these nutrients to help them grow (just like you need things like proteins, carbohydrates, and sugars found in the food you eat). These nutrients come from all different sources including fertilizer on lawns (and croplands) washed away by the rain, from water flushed through the soil, and from rainwater running off of roads and parking lots. The nutrients end up in the rivers and then the estuary where phytoplankton use these nutrients, in addition to the increased light from the sun, for growth. Just like the April showers help plants grow on land by providing water, the phytoplankton use the extra nutrients flushed into the estuary by the April showers to grow!

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A spring revival in the marshes, too! Things are starting to look greener.

Not only do changes happen in the estuary itself, but along the marshes, as well. Things get greener (common theme in this post…) but interesting things start happening to the nutrients as well (the second common theme of this post). Our resident nutrient-cycling in marshes expert, Kathleen, said spring is the time when denitrification starts to pick-up. Denitrification is the process where reactive forms of nitrogen (often found in things like the fertilizer run-off and road way run-off we talked about earlier) is turned into un-reactive forms of nitrogen by microbes. Spring is also the time of year when marsh scientists, like Kathleen, are able to go back to their field sites after a long, hard winter. Often times, Kathleen said, the field sites are almost totally unrecognizable thanks to storm erosion during winter!


Fully enjoying the benefits of spring!

So, as you enjoy all the benefits of spring, from the flowers blooming to the warmer temperatures, remember the tiny phytoplankton and the large marshes who are also enjoying the warmer weather, more abundant daylight hours, and increased nutrients from April showers, too! Happy Spring!

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