,“
250 ”
“{
G.
{
0.4
ammonia
,
,
,
“
«”
0.1———
diffusion to atmosphere 0.2
,,
surface
.
,
,
pond-water column
,
,
_
-
-
,
[steady state
ammonia
_
<————fish growth 0.1
-
concentration 2 ppm]
_
recipitation of organics
,
,
into sediments 0.3
sediment surface
_
__
-
_
/////////////////////////////////////////////////////////////////////
ammonium ion,
;
,
…
,
diffusion from sediments 0.1
,
,
;
*
[present and increasing
ammonium ion
.
ammnium concentration
diffusion into deeper sediments 0.l
at 1 cm into the
,
,
ments 50ppm]
Figure 1 : Nitrogenflux in a fish
approximately
-
'
after-filling and stocking. Numbers aregm N/sqm/day. ,.
,
Bottomdigging
of ammonia from the sediments by
-overlying water- Counter “CC?
the falling sed—jument particles can remove the ,ammonia
the
prec1p1tat1@n
.:'(:v
:
:Ï'Î
,
.
:_
_
"
,_
:,
A
pond bottom BODof 3gm/sqm/dayaccounts for ox1c respiration of
approximately 3 gm organic matter , (Eqn.
l) .
For a range Of detrital sedi—
ments, - -
total organic decay has beenestimated to
theox1c
decay (see references Cited in Howarth and Hobbie 1982") ‘
poten—
tial ?L:Î9r1,
of;
—9m/sq ,m/dayIf
thlSlsa19&lorgæm matter, and
mnia»releæe
ù®alæseebëWæ N added… to an@
remvedfmmthesedments…acÇQunts«—f@r
,,
in… interstitial
ammma concentrations
Of fish pondS as
ÜïeS€as®npr©gresses
%
z
,
There dœsn@tappear tobea cleardlstmctmnbetwæn the relative
roles that suspendeä andsessüe natural foods take ln ta;get ail
growth YaShŒV< 1971)demenstraŒdasymbmtlClnteraetwnbetwæn SC and
thanthesm@fthæÿleldswhenthæe flshwere grown separateïy
m@erstooä- the
t<î>. the feœs .,0”f,
…
the
filter“
dlggmg Ofthe CC suspendedpamuläeorgamc matter andchemcals, thü$
enr1‘ch1ng the water column for the benefit of the SC
In
pellet—fed ponds stocked 'With 1000 to 5000 CC plus tilapiâ