*
L BIOLOGY
repartition
;j‘=“ _ The species iS"_ Strictl'y conn*edÿtoï the
layer1ts
'
max1mum
-
b etween 0< } and" ‘30’nigf Aam‘æs 11venearte
surface duringà thè"day and“
mghtCope
‘îodites
the "
opposite and
fdüd
-
close
the “surface.
'
“
_
Great deriSities of population are found mamly 1nnenüc
waters but outside a dened. coastal
Characterize(T by
dŒhinàn0ebf the genus
to be under
inuence Of
'or*eXcess of“ natural organic matters.
—MicrÔdi-Stbutibh shows
'
off—shore Waters ‘in“ the hays
Argi:érsf”and
(f1gs "7 &“8);
ne.ust0nicpatch
;
density of
high“as
adu1-tsgîter
(chap L @: IIÏ, 3)_1
‘
»
,
——
is
or absent 3 in regions
%y
or hoi*îZohtàl tur‘büléncè,
stability of water layers seems to
-
Ë'ïôonlditîons
'
foi—' ‘5T.
"
'stgzifefa’s"
‘
yäfe1fare… {Theh; these ai‘stuÿhed
zones
hÿafoïogi”càl barrierïs
; ;ë.w1?eg‘ions, .Which several geographical races belong
races
have
requirements
great morphological differencieS. ;
°
Annual distribgtion. }
,
_
__
_
——
In: Mediterranean,» f—T:
on
February and» March… Maximum
f09€
7
‘
_
to the, "1ccality, gen er…ayf when thetemPô'
reaehesZQ°5 1: 2°
[
Available data Show this maximum' takesplacebetween
—3='Julÿi and
i=s
{
; V. j —
October}
equalorhlgherthan
‘
'
38 %… LTheî highest guré-s : of populaüondens1t1œa1eglven
î
Golfe, …du—ï… Lion {8.000 zto… 310.000md1v1uals/m3),eastern
-
_
coast of Goî—se',ïü Gatàloniatr =côast;;gulfofGema(70%0fthe
total nuŒe1®f:@op€poè)-—J