Cardiac and Locomotory Muscle Mass in Antarctic
Fishes
Russell F. Robertson!, Nia M. Whiteley!, and Stuart Egginton 2
!School of Biological Sciences
2Department of Physiology, University of Birmingham, Edgbaston, Birmingham
B15 2IT, UK
Introduction
The fish fauna around Antarctica is dominated by a single perciform
suborder, the Notothenioidei, whose phylogeny has been well defined by
traditional and molecular techniques. They have undergone a remarkable
adaptive radiation (into a variety of forms from small, sculpin-like to
large, hake-like species) that is possibly unique in the marine environment,
and which molecular evidence suggests is a relatively recent event [1]. The
last few decades have seen the development of extensive scientific and
commercial fishing in the Southern Ocean that has provided much data on
the growth and reproduction of a wide range of species. In contrast,
financial constraints and logistical difficulties have meant that studies into
the physiological mechanisms that allow these fishes to successfully
exploit this extremely cold and highly seasonal environment have mainly
concentrated on a few species, predominantly from Nototheniidae and
Channichthyidae [2,3]. Antarctic pelagic fishes are diverse in their origins,
coming from bathypelagic, mesopelagic and, of most interest for our
purpose, from coastal fish families that have become secondarily adapted
to midwater life. However, most species (about 75% of those so far
recorded) inhabit benthic or demersal niches, which is thought to reflect
the benthic lifestyle of the parent taxa, and helps explain the lack of a
functional swimbladder [2]. Those species that are now able to exploit the
water column have had to evolve means of adjusting buoyancy, including
reduced skeletal ossification and extensive lipid deposits [3]. Other
adaptations may also exist, e.g. the Antarctic silverfish, Pleuragramma
antarcticum, is streamlined and shows a reliance on subcarangiform
locomotion. In contrast, the notothenioids have large pectoral fins which
are utilised in labriform locomotion, providing a sculling movement
during swimming while the trunk acts mainly as a rudder. This reflects the
benthic origins of this group and the maintenance of relatively low activity
O. di Prisco, E. Pisano, A. Clarke (Eds)
Fishes of Antarctica. A biological overview
© Springer-Verlag Italia 1998
Fishes
Russell F. Robertson!, Nia M. Whiteley!, and Stuart Egginton 2
!School of Biological Sciences
2Department of Physiology, University of Birmingham, Edgbaston, Birmingham
B15 2IT, UK
Introduction
The fish fauna around Antarctica is dominated by a single perciform
suborder, the Notothenioidei, whose phylogeny has been well defined by
traditional and molecular techniques. They have undergone a remarkable
adaptive radiation (into a variety of forms from small, sculpin-like to
large, hake-like species) that is possibly unique in the marine environment,
and which molecular evidence suggests is a relatively recent event [1]. The
last few decades have seen the development of extensive scientific and
commercial fishing in the Southern Ocean that has provided much data on
the growth and reproduction of a wide range of species. In contrast,
financial constraints and logistical difficulties have meant that studies into
the physiological mechanisms that allow these fishes to successfully
exploit this extremely cold and highly seasonal environment have mainly
concentrated on a few species, predominantly from Nototheniidae and
Channichthyidae [2,3]. Antarctic pelagic fishes are diverse in their origins,
coming from bathypelagic, mesopelagic and, of most interest for our
purpose, from coastal fish families that have become secondarily adapted
to midwater life. However, most species (about 75% of those so far
recorded) inhabit benthic or demersal niches, which is thought to reflect
the benthic lifestyle of the parent taxa, and helps explain the lack of a
functional swimbladder [2]. Those species that are now able to exploit the
water column have had to evolve means of adjusting buoyancy, including
reduced skeletal ossification and extensive lipid deposits [3]. Other
adaptations may also exist, e.g. the Antarctic silverfish, Pleuragramma
antarcticum, is streamlined and shows a reliance on subcarangiform
locomotion. In contrast, the notothenioids have large pectoral fins which
are utilised in labriform locomotion, providing a sculling movement
during swimming while the trunk acts mainly as a rudder. This reflects the
benthic origins of this group and the maintenance of relatively low activity
O. di Prisco, E. Pisano, A. Clarke (Eds)
Fishes of Antarctica. A biological overview
© Springer-Verlag Italia 1998