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

Table 15. Energy in various ccmpartments of an eelgrass bed in Mrth Carolina (after
Thayer et al. 1975b).
compartment Energy value in Ehergy input to Energy lost f m
ccmpartment ca~partment
(kcal/d/yr) (kcal/d/yr)
1. Primary prducer
Eelgrass 135
Benthic algae 18
Phytoplankton 1
2. Detritus production 21,160
3. Bacteria, microfauna, 47
Meiofauna
4. Nekton 6
6. Infauna 30.7
transient residents, some on a seasonal
basis, and some on a diurnal basis.
A relatively new technique has been
employed to delineate the flows of carbon
from plants to nimals in seagrass food
webs. the del 'C or 13c/12c ratio. The
technique assumes that individual plant
species or groups possess stable ratios,
that these ratios are retained in carbon
flows, and that the isotope ratios of
animals are a function of their diet.
While the procedure will not identify the
specific food-web importance of a seagrass
species, it is useful in analyzing the
food-web importance of seagrasses as a
group (Fry et al. 1982).
Much research is needed on eelgrass foodweb
relationships in the Pacific
Northwest. The best work done to data on
a descriptive basis is that of Simenstad
et al. (1979; Figure 20) and a diagram
prepared for an Army Corps of Engineers
report (ACOE 197713; Figure 21). There is
a need for quantification of work of this
sort, as well as quantifying the energy
flows through the various trophic
compartments and the amount of leaf
material and detritus exported from the
eelgrass system in the Pacific Northwest.
Figure 22 diagrams the principal energy
pathways in a typical eelgrass meadow in
the Pacific Northwest.