SEA PATCHES

The how and why large numbers of small zooplankton gather in patches in the sea

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We study how patches of plankton form in the ocean

An ongoing question in marine ecology considers to what degree plankton distribution is determined by physical or biological factors. The Sea Patches project aims to find some answers.

The ocean is in a constant state of movement. Currents mix the water and the small plants and animals - the phytoplankton and zooplankton - inhabiting the seas. Yet the distribution of marine life is patchy.

Species distribution is also affected by animal behaviour related to biological tolerances. We can observe distribution patterns that differ across climatic zones, i.e., regional environments.

On a smaller scale, the swarms of many marine species do not follow the physical forces of ocean currents. Even plankton organisms of just about 2 mm size have been observed in large aggregations at surface!

Traditional sampling methods, such as nets deployed from boats, make it difficult to collect data without disrupting the zooplankton before sampling has begun. This leads to unintentional invasive techniques that create bias in data sets. And so the mechanisms of zooplankton patch formation in the ocean are poorly understood.

Calanus finmarchicus under the microscope

New Technologies for Biological Oceanography

Our scientists use new technologies to sample zooplankton using non-invasive methods, allowing for research findings that more closely tell the story behind zooplankton distribution.

We use modern technology, such as remote sensing and optical plankton counters, in combination with the latest marine physcial-biogeochemical models to:

locate zooplankton patches
analayse zooplankton patch structure in detail
describe the physical and biological mechanisms of zooplankton patch formation

Recent developments in new technology have made it possible to analyse plankton distributions on much smaller scales while simultaneously measuring physical factors. Observations now point to organisms actively forming patches and even tiny animals can maintain their position against currents.

Calanus finmarchicus

Our focus species is the small crustacean Calanus finmarchicus, a lipid-rich copepod that is a major food for many commercially harvested fishes. Calanus has its own fishery because of its high levels of omega-3 fatty acids.

A patchy distribution makes it challenging to correctly estimate Calanus stock size – crucial data for effective fishery management.

The Sea Patches project will thus also contribute to a sustainable harvesting of a species at the bottom of the marine food web, Calanus finmarchicus.