The Ecology of Tijuana Estuary, California: An Estuarine Profile

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Figure 2. The northern arm of Tijuana Estuary, looking east (photo by O. Fink).
1.3 THE ESTUARINE HABITATS
Tijuana Estuary is a wetland-dominated estuary
(Figures 2-31, There is no major embayment, but
rather a series of channels and a relatively narrow
ocean connection. In most years, the mouth has
been open, and tidal flushing has prevailed. The
intertidal area supports mostly salt marsh
vegetation, while mudflats and sandflats occupy
only a small fraction of the site. Inland, the upper
salt marsh grades into transitional vegetation,
which in turn grades into coastal scrub and
chaparral.
Many features of the estuary have been
substantrally Influenced by disturbances of both
natural and human origin Natural fiood~ng In 1980
broadened the rrverbed and changed its course
Wtnter storms in 1983 washed the dunes ~nto the
marn channels and obliterated two salt marsh
islands In the ear!y 1900's, sewage d~sposal
practices led to the dredgrng of an east-west
channel to connect the estuary to an adjacent
lagoon Orkes were later constructed to subd~vrde
that Lagoon tnto three wastewater receivrng ponds,
which were subsec;uently abandoned and the drkes
breached to rmprove trdal fltishrng Gravel
extractton for street and dlke construction left
rsolated ponds wrthrn the estuary. Long-term
dumplng and fliling altered most of the peripheral
topography, and off-road vehlcles denuded many
roads and paths Scars remain throughout the
southern half of the estuary from farmer m#lltary,
agricultural, and horse-rarsrng activities Presentday
sewage sp~lls from Mexlco change the quantity,
and certainly the quality, of lnflowlng waters.
Can any area that has experrenced such
extens~ve assaults stlll be considered a naturally
functronlng estuary? The closest we can come to
answerlng that question is to compare !t wlth more
disturbed systems near Los Angeles and wrth less
d~slurbed systems In Baja Callfornla Tijuana
Estuary ranks wrth the latter
In 1982, the National Oceanrc and Atmospner~c
Adrnrntstrat~on (NOAA) designated Tljuana Estuary
a National Estuartne Sanctuary, in recognition of its
value as a research and educational resource. A
long record of use rn estuanne research and the