Biology Reference
In-Depth Information
Figure 3.
Comparison of observed metamorphosis in
P. marinus
and metamorphosis predicted
using a condition factor criterion of 1.45 or greater in the fall. Prediction bars topped with
asterisks (**) differ signifi cantly from the corresponding observed bars. Treatment combinations
consist of low-temperature (LR), high temperature (HR), and cold temperature (CT) regimes
and of low (LD) and high (HD) larval densities. See the text for further detail and the
signifi cance of these data. (From Holmes and Youson, 1997).
production, and stream latitude and longitude was a 20% more effective
than any other model (Treble
et al
.
, 2008).
In contrast to the above, a study of metamorphosis in the non-parasitic
species,
Lampetra appendix
, showed that the size and condition factor
parameters of
P. marinus
do not apply as easily to this species. Firstly, the
larvae of
L. appendix,
that often cohabit with
P. marinus
, metamorphose at
lengths of 155 to 189 mm and masses of 5.40 to 9.74 g. The CF of the earliest
metamorphosing animals was 1.25. Statolith aging of
L. appendix
indicates
that they are at least 1 year older than
P. marinus
when they commence
metamorphosis (Beamish and Medland, 1988). The large size of this species,
rather than lipid reserves as in
P. marinus
, might refl ect both the preparation
for the non-trophism of metamorphosis and that they will commence sexual
maturation immediately after completing metamorphosis. The mean lengths
and mass, and the CF of immediately pre-metamorphic individuals of the
much smaller, parasitic, southern hemisphere lamprey,
G. australis
, were
~90 mm, 0.95 g, and 1.35, respectively (Potter et al
.
, 1980, 1982). The decline
in mass and CF during the metamorphosis of
G. australis
suggests a similar
pattern of utilization of fat stores during metamorphosis, without the cost
of any major change in length, that most closely resembles the situation in
P. marinus
(Potter et al
.
, 1978b, 1982).
