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Dinoflagellate behavior modification in the presence of predators

Fruh, Johan (2015) BIOY01 20131
Degree Projects in Biology
Abstract
Diel Vertical Migration (DVM) in the aquatic environment is of great ecological importance. In order to better understand and predict this fabulous orchestra of migrating biomass, the underlying behaviors behind each individual’s swimming tactics need to be better understood. While vertical migrating behaviors in animals such as zooplankton and fish have been deeply investigated, phytoplankton behavior, however, remains a more sparse study case.

In this project, the swimming behavior of four phytoplankton (dinoflagellate) species was observed with a 2d microscope filming procedure. The goal was to assess any differences in swimming tactics whether individual dinoflagellate cells were in the presence of predators (living zooplankton or... (More)
Diel Vertical Migration (DVM) in the aquatic environment is of great ecological importance. In order to better understand and predict this fabulous orchestra of migrating biomass, the underlying behaviors behind each individual’s swimming tactics need to be better understood. While vertical migrating behaviors in animals such as zooplankton and fish have been deeply investigated, phytoplankton behavior, however, remains a more sparse study case.

In this project, the swimming behavior of four phytoplankton (dinoflagellate) species was observed with a 2d microscope filming procedure. The goal was to assess any differences in swimming tactics whether individual dinoflagellate cells were in the presence of predators (living zooplankton or zooplankton cues), or not. The filmed phytoplanktons consisted of three dinoflagellate species: Heterocapsa triquetra, Alexandrium minutum, Prorocentrum minimum, and one raphidophyte: Heterosigma akashiwo.

Results show a clear change in behavior in the presence of predators for A. minutum and H. triquetra. Furthermore, H. triquetra experiences what appears to be a perturbation in its life stages when in the presence of a predatory cue. Results for P. minimum and H. akashiwo were inconclusive. (Less)
Popular Abstract
Diel vertical migration is the behaviour with which many aquatic organisms regularly move between surface and deeper layers of the water column. It is considered to be the most important migration on the planet in regard to biomass, and it happens daily. The migration has an important role in absorbing carbon dioxide at the surface and transporting it to the depths, transporting nutrient and material to the surface from the depths, and in the formation of harmful algae blooms. In order to better comprehend the mechanisms behind the migration, it is important to understand the individual behaviours that produce the daily movement. One of the strong factors considered to be responsible is the need to evade predators. While this has been... (More)
Diel vertical migration is the behaviour with which many aquatic organisms regularly move between surface and deeper layers of the water column. It is considered to be the most important migration on the planet in regard to biomass, and it happens daily. The migration has an important role in absorbing carbon dioxide at the surface and transporting it to the depths, transporting nutrient and material to the surface from the depths, and in the formation of harmful algae blooms. In order to better comprehend the mechanisms behind the migration, it is important to understand the individual behaviours that produce the daily movement. One of the strong factors considered to be responsible is the need to evade predators. While this has been strongly studied in fish and zooplankton, it has largely been ignored in phytoplankton.

The goal of this project was to identify how a type of phytoplankton (Dinoflagellates) behave when their predators are present. To do this, an experimental setup was created in order to film six flasks containing a species of Dinoflagellate, three flasks of which also contained predators (copepods) or predatory cue (crushed copepods). The behaviours of the phytoplankton were analysed by recording their swimming trajectories and evaluating how straight they were, their speed, their average direction, and by keeping track of how many individuals passed in front of the camera.

The results showed that two species of Dinoflagellates (Alexandrium minutum and Heterocapsa triquerta) heightened their speeds and swam in straighter lines when in the presence of predators or predatory cue. For H. triquerta, it showed the individuals changing their behaviour after only 3 hours in the presence of predators, which is much faster than their change in behaviour due to nutrients becoming available (24 hours). This can have strong implications regarding how these phytoplanktons’ gamete cells (reproductive individuals) and vegetative cells (dispersing individuals) are studied. Additionally, the results offer interesting directions for research in developing tools to fight harmful algae by disrupting gamete life-stages with predatory cues.

Supervisor: Per Carlsson
Degree Project in Biology 30 credits, 2015
Department of Biology, Lund University (Less)
Please use this url to cite or link to this publication:
author
Fruh, Johan
supervisor
organization
course
BIOY01 20131
year
type
M2 - Bachelor Degree
subject
language
English
id
8596405
date added to LUP
2016-02-03 13:34:21
date last changed
2016-02-03 13:34:21
@misc{8596405,
  abstract     = {Diel Vertical Migration (DVM) in the aquatic environment is of great ecological importance. In order to better understand and predict this fabulous orchestra of migrating biomass, the underlying behaviors behind each individual’s swimming tactics need to be better understood. While vertical migrating behaviors in animals such as zooplankton and fish have been deeply investigated, phytoplankton behavior, however, remains a more sparse study case.

In this project, the swimming behavior of four phytoplankton (dinoflagellate) species was observed with a 2d microscope filming procedure. The goal was to assess any differences in swimming tactics whether individual dinoflagellate cells were in the presence of predators (living zooplankton or zooplankton cues), or not. The filmed phytoplanktons consisted of three dinoflagellate species: Heterocapsa triquetra, Alexandrium minutum, Prorocentrum minimum, and one raphidophyte: Heterosigma akashiwo.

Results show a clear change in behavior in the presence of predators for A. minutum and H. triquetra. Furthermore, H. triquetra experiences what appears to be a perturbation in its life stages when in the presence of a predatory cue. Results for P. minimum and H. akashiwo were inconclusive.},
  author       = {Fruh, Johan},
  language     = {eng},
  note         = {Student Paper},
  title        = {Dinoflagellate behavior modification in the presence of predators},
  year         = {2015},
}