By Louis Byrne, British Oceanographic Data Centre, NOC
We woke up
on Monday to a sea which was perhaps even worse than Sunday. We were still a
fair distance away from site A and were not scheduled to reach site A till
approximately 2100 Monday evening. Due to the rough seas I spent the majority
of the day hugging my toilet bowl, but not before making the rookie mistake of
blocking my sink with the remains of my breakfast, which Geoff the Steward was
not too happy about. Due to a day spent
in transit not much happened, and due to my sea-sickness I was not around to
see what did, therefore I thought it would be a good time to introduce the
reason why we’re rushing towards the Celtic Sea at a slow and steady speed of
seven knots.
Although
shelf seas make up only 5% of the ocean surface, they have been estimated to be
the most valuable biome on earth, with high levels of primary productivity
supporting diverse ecosystems. High concentrations of nutrients support the
growth of phytoplankton, which are single celled marine organisms that
photosynthesise like plants on land. Like plants on land, Phytoplankton are the
base of the marine food web and they provide a diverse food source for many
marine creatures, such as zooplankton.
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Phytoplankton are the foundation of the oceanic food chain. |
Zooplankton
are tiny marine animals which are food for fish and countless other marine
organisms, that are then in turn eaten by others. It is in this way that the
sun’s energy fixed by phytoplankton on the surface of the water column is
distributed throughout the marine ecosystem, underpinning more than 90% of
global fisheries and offering many other important ecosystem services.
In addition
to supporting the entire marine food web, the photosynthesis carried out by
phytoplankton also removes significant amounts of carbon dioxide from our
atmosphere. Although tiny, phytoplankton
have a disproportionately massive effect on our atmosphere, and are responsible
for creating as much as half of the oxygen that we breathe, removing an equally
large amount of carbon dioxide as they do it. Some of the carbon extracted by
the phytoplankton will sink to the sea floor and be stored in the sediments
(often for thousands of years!), reducing the overall concentration of carbon
dioxide in our atmosphere.
In order for
the shelf seas to sustain these high levels of production, the phytoplankton
must be supplied with nutrients, but where do these nutrients come from? It is
the need for us to better understand the role of shelf seas in the global
nutrient cycle, how this supply of nutrients determines the shelf’s primary and
secondary production and how this affects other processes such as carbon
storage which has led to the Shelf Seas Biogeochemistry programme.
At 2100 on
Monday night we reached site A and decided that the seas were too rough to
sample that night. Therefore, an 0600 hours CTD cast was scheduled for the
following morning, and we were hopeful that our cruise was about to get its
first piece of data.
For those of
you wishing to see the answer to yesterday’s question, the answer is Richard
Cooke of the National Oceanography Centre, Liverpool.
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