The Ecology of the Seagrasses of South Florida - USGS National ...

CHAPTER 6
TROPHIC RELATIONSHIPS
IN SEAGRASS SYSTEMS
6.1 GENERAL TROPHIC STRUCTURE than previously suspected; however, it
still appears that the detrital food web
Seagrasses and associated epiphytes is the primary pathway of trophic energy
provide food for trophically higher organ- transfer (Zieman et al. 1979; Kikuchi
isms by (I) direct herbivory, (2) detrital 1988; Ogden 1980).
food webs within grass beds and (3) exported
material that is consumed in other Stud1 es have attempted to measure the
systems either as macropl ant material or proportion of daily seagrass production
as detritus (Figure 22). Classically the which is directly grazed, added to the
detrital food web within the grass beds 1 i tter layer, or exported. Greenway
has been considered the primary pathway, (1976) in Kingston Harbor, Jamaica, estfand
in most cases is probably the only mated that of 42 g/mL/wk production of
significant trophic pathway. During the turtle grass, 0.3% was consumed by the
past few years, new information has been small bucktooth parrotfish, Sparisoma radgathered
on the relative role of the other ians; 48.1% was consumed by the urcK
modes of utilization. The picture marg- -chinus ariegatus; and 42.1% deposited
ing is that in many locations both the %
on t e ottom and available to detritidirect
utilization pathway and the export vores. The rest of the production was
of material may be of far more importance exported from the system. This study may
/-- -"#----'---- .-------.
-
i"
LP'~
DRIFT €3,
EXPORT
DECAY,
PLANT CANOPY 4
STRUCTURE
PRODUCTION
Figure 22.
.. .
Principal energetic pathways in seagrass beds.
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