Planktonic Communities

Background

Planktonic species formulate the base of most oceanic food webs. Producers, such as phytoplankton, at the base of the food chain are the first to respond to changing oceanic conditions. Signals of change at all time-scales can be found within the plankton; from shifts in community composition due to increasing global temperatures over decades to the genetic responses of unicellular algae caused by features of ocean circulation that can change in a matter of minutes.

 

Topics

Community ecology

A community is composed of a group of interacting organisms or ‘biological assemblage’ that are associated with particular environmental conditions. The biological assemblage that comprises a community can be quantitatively characterised by the presence/absence and relative abundance of its species or functional groups. By monitoring changes to the planktonic community in conjunction with fluctuations in oceanographic conditions we can directly measure the impact of oceanographic phenomenon such as typhoons or long term changes associated with global climate change.

Our plankton community data is collected in the form of individual images from continuous and semi-continuous monitoring programs. 

The continuous monitoring program is in the form of a cabled observatory system, named the OIST OCTOPUS, installed on the seafloor on the North-West coast of Okinawa Island at 20m depth. Plankton community data is also collected semi-continuously from aboard the Tonan-Maru research vessel during regular sampling from set locations along the west coast of Okinawa.

As well as these long-term studies, we are also collecting plankton image data from hydrothermal vents and other areas pertinent to other areas of ongoing research.
By using images of planktonic species, it is possible to employ automated image analysis techniques to process large amounts of data in short time and consistent manner. We are looking into improving our automated analysis techniques and getting involved with the global scientific movement toward automated identification.

Genetic Diversity and Function

By extracting DNA and RNA from a seawater sample we can obtain added information on the composition of the planktonic community that may be overlooked by the imaging process. As well as relative abundance information, RNA extraction can indicate the type of processes being carried out by the community. For example, similar biological assemblages may exhibit very different modes of production and the same species may have an alternative relationship with its conspecifics based on environmental conditions.