111
H.-J. Ceccaldi et al. (eds.), Marine Productivity: Perturbations and Resilience of Socio-ecosystems,
DOI 10.1007/978-3-319-13878-7_12, © Springer International Publishing Switzerland 2015
Abstract
Oithona davisae is a planktonic cyclopoid copepod species, known to be
extremely abundant and often predominates in coastal marine embayment.
To understand why this animal is so successful, we have been looking into
its swimming ability to escape from predators. Here we show how O. davisae escapes from the moon-jelly Aurelia aurita , which devours zooplankton
and occurs in a huge number in embayments including Tokyo Bay. Direct
observations revealed that O. davisae is agile enough to escape from the
moon-jelly’s ephyra larvae, which appear much more numerously than adult
moon-jelly. This agility reducing the predation mortality may be crucial for
O. davisae to predominate in this bay and somewhere else that are full of
predators. Direct observations by the use of video cameras suggested that
O. davisae may be recognized as a genius in escaping from predators, comparing with some other planktonic animals such as Acartia (larger copepod),
barnacle cypris , decapod zoeas, etc., being less agile than O. davisae .
Y. Tanaka (*)
Tokyo University of Marine Science and Technology ,
4-5-7 Konan , Minato , Tokyo 108-8477 , Japan
e-mail: ytanaka@kaiyodai.ac.jp
T. Akiba
National Institute of Advanced Industrial Science
and Technology , 1-1-1 Higashi ,
Tsukuba, Ibaraki 305-8522 , Japan
e-mail: ta-akiba@aist.go.jp
Oithona davisae , the Most
Predominant Copepod in Tokyo Bay,
a Highly Eutrophic Embayment:
Why Are They So Predominant?
Yuji Tanaka and Tatsuro Akiba
1
Introduction
Among various factors, anthropogenic loading and
global warming are considered to be causing signifi cant changes in the coastal marine environment.
We need to holistically understand mechanisms
in such changes to predict how the environment
would be in the future. Prerequisite is detailed
knowledge on biological processes as well as
physical and chemical ones in response to the
environmental changes. Planktonic copepods are
important in the aquatic ecosystems because of
their abundance and diversity; they are considered to bridge the primary producers (phytoplankton) and higher consumers (such as larger
zooplankton and fi sh). (Nishida 1985 ; Tsuda and
Nemoto 1988 ; Itoh and Aoki 2010 ).
Among them, a cyclopoid copepod Oithona
davisae (Fig. 1 ) is one of the most predominant
species in the zooplankton community of coastal
H.-J. Ceccaldi et al. (eds.), Marine Productivity: Perturbations and Resilience of Socio-ecosystems,
DOI 10.1007/978-3-319-13878-7_12, © Springer International Publishing Switzerland 2015
Abstract
Oithona davisae is a planktonic cyclopoid copepod species, known to be
extremely abundant and often predominates in coastal marine embayment.
To understand why this animal is so successful, we have been looking into
its swimming ability to escape from predators. Here we show how O. davisae escapes from the moon-jelly Aurelia aurita , which devours zooplankton
and occurs in a huge number in embayments including Tokyo Bay. Direct
observations revealed that O. davisae is agile enough to escape from the
moon-jelly’s ephyra larvae, which appear much more numerously than adult
moon-jelly. This agility reducing the predation mortality may be crucial for
O. davisae to predominate in this bay and somewhere else that are full of
predators. Direct observations by the use of video cameras suggested that
O. davisae may be recognized as a genius in escaping from predators, comparing with some other planktonic animals such as Acartia (larger copepod),
barnacle cypris , decapod zoeas, etc., being less agile than O. davisae .
Y. Tanaka (*)
Tokyo University of Marine Science and Technology ,
4-5-7 Konan , Minato , Tokyo 108-8477 , Japan
e-mail: ytanaka@kaiyodai.ac.jp
T. Akiba
National Institute of Advanced Industrial Science
and Technology , 1-1-1 Higashi ,
Tsukuba, Ibaraki 305-8522 , Japan
e-mail: ta-akiba@aist.go.jp
Oithona davisae , the Most
Predominant Copepod in Tokyo Bay,
a Highly Eutrophic Embayment:
Why Are They So Predominant?
Yuji Tanaka and Tatsuro Akiba
1
Introduction
Among various factors, anthropogenic loading and
global warming are considered to be causing signifi cant changes in the coastal marine environment.
We need to holistically understand mechanisms
in such changes to predict how the environment
would be in the future. Prerequisite is detailed
knowledge on biological processes as well as
physical and chemical ones in response to the
environmental changes. Planktonic copepods are
important in the aquatic ecosystems because of
their abundance and diversity; they are considered to bridge the primary producers (phytoplankton) and higher consumers (such as larger
zooplankton and fi sh). (Nishida 1985 ; Tsuda and
Nemoto 1988 ; Itoh and Aoki 2010 ).
Among them, a cyclopoid copepod Oithona
davisae (Fig. 1 ) is one of the most predominant
species in the zooplankton community of coastal