The ecology of eelgrass meadows in the Pacific Northwest: A ...

Table 10. rison of elemental oanp
sition of eelgrass and tk man (after
Mclby 1970a).
changes in primary production,
decomposition of plant matter, and
reliance on detritus for food and
nutrients as the ecosystem develops in
time. It appears that processes change
a long recognizable sequences, mcm r talt
with species and structural cfmqes.
Major elmnix
~XMm
kfydmqttn
Carban
'Iskosphorus
Nitrogen
Minor elmntrr
Wiun
Chlorine
Magnee iun
Pstassim
SulEur
(=Qlcim
lk3m
Silicrm
Iditw
Zinc
Irotl
A1 unir~un
Mrqipf14a~e
McRoy and Williams (LY7k3) defined
processing as all brotic and dblotrc
interactions resulting in the
transformation of particulate organic
matter. Temperature, chernrcal
composif ion, animal, dnd nlicrobral
activity, desiccation, aerobrc and
anerob~c condit~ons, and particle slze
affect procosslng rates.
It is krrown that eelgrass processes change
along tem~ral and spatial gratlrents. 'he
spatial gradient may lie frorn the edge to
the center of a single meadow or along a
latitudinal gradient froin an ared wlth
optimal environmental conditions where
ecoeystefn developmetat has proceeded
raprdly to stressed dress dt the twrtherly
anJ wutherly l~mits of distribution where
ecosystem development has been retarded.
Kenworthy et al. (1982) described a
sequence in nitrqen accumulation alimg a
local spatial gradient in an estuary in
North Carolina. The greatest pool of
rlitrogen was in the midbed; the
mtenn&iate level was at the edge of the
meatlow, and the least nitrogen was in
unvogeti-ited sediment. These nitroyen
changes were correlated with
concentrations of fine particle slze in
the sedirnents, a clmracteristic assoclatd
with the eelgrass. Dennison (1979)
cbcurnented the charyes in leaf area infex
and light responses of eelgrass as a
~[~itial gradlent of ecosystem development
in Zzembek Lagoon, Alaska. It has been
possible to transplant eelgrass frorn Puget
M, Washington, to Izembek Lagoon, but
not vice Versa. This suggests that
eelgrass has a much broader adaptive
tolerarice from an area with optlmtll
Pacific WrUzwe~t, particularly in Orqm enviraunenkal mutitions and can tolerate
arrtl. eouthweaterr~ Washington, just as 2.- tlle stress in Xzembek Lagoon. The plants
jawnlg grow8 intermrxec3 with eelgrass fran Xzembuk Lagoon do rmt appear to have
itlong rts Xswer timrt of growth (fidrrison as broad an adaptive tolerance to
1979). This mixmcj cannot be interpreted corxiitions elsewhere (Phillips and Lewis
L~I elcher case to be species s~~cc~*ession. 1983) .
Functional or process succession relates What appears to be a simple ecosystem,
to the quantitative and qualitative structurally and functionally, merely
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