The Ecology of Tijuana Estuary, California: An Estuarine Profile

Table 2Q. Standing crop (g dry wt/m2) of major salt marsh
vascular plants for March (minimum biomass) 1976, 1977 and
August (biomass peak) in 1976, 1977, and 1978 (from Winfield
1980).
Species 3/76 8/76 3/77 8/77 8/78
Batis marillma
saltwort 15 55 55 121 82
Jaurnea carnosa a 218 66 181 195
Monanthochloe littoral~s
shore grass a 170 159 218 143
Sal~cornia bigelovii
annual p~ckleweed i 1 35 9 125 85
S v~rgin~ca
prckleweed 31 124 55 179 173
Spart~na foliosa
cordgrass 55 21 1 130 280 256
Total standrng crop 426 858 514 1153 954
aJaumea and shore grass were not separated In the March 1976 sarrlple
there is a net flux of Inorganic nitrogen from the
ttde waters to the marsh His estimate of the
amount of n~trogen imported by the marsh (2 2 g
N/mZ/yr) was far less than the total required for
above-ground plant growth (only 28x1, and even a
smaller portion of the nitrogen required for
vascular-plant and algal productrvrty combined
(6%) Whrle these calculations do not rule out
phosphorus or other nutrients as limiting, they do
show a nltrogen deficit
Standii-icj Dead
Weiqh! I
MAMJ J ASONDJ FMAMJ JASONDJ FMAMJJ ASON
1976 1977 + 1978
Figure 52. Live biomass and dead standing crop for
salt marsh vascular plants. Vertical bars are Ll
standard error, n - 25. Reprinted with permission from
Winfield (1 98Q).
Table 21. August biomass in the cordgrass marsh
areas only (from Zedler et al. 1980 and Zedler 1982b).
s.e. = standard error
--
Year g/m2 s e
1976 914 38
1977 1099 63
1978 1032 38
1 980 1400 113
J
Data from the San Dtego Regional Water Quality
Control Board (G. Peters, WQCB, pers comm)
show high ratios of phorphorus to nitrogen, so that
phosphorus is less likely to limit whole-system
productivrty than nitrogen Freld sampling of sorl
nitrogen (Covin 1984) and channel nitrogen
concentrattons (Winfreld 1980, Rudnickr 1986,
Fong 1986) indicate that inorganic nitrogen is often
present ~n very low quantities Nttrogen fixation
rates have not been measured
In most of the experimentaf work carried out at
Tijuana Estuary, nttrogen additrons have stimulated
vascular piant growth (Covln 1984) in 1983,
frequent sewage sp~lls from Mexleo turned our
attention to the more practrcal problems of how
wastewater affects estuar~ne organisms, and
nutrient-algae interactions were ~nvestigated In
manipulative expeilments using Milorganrte
(commercraily avaflable dried sewage sludge). The
work of Rudnicki (1 986) and Fong (1 986, Section
4 11 focused on channel macroalgae and
phytoplankton, whfle that of Beare and Beezley
(unpubl data) dealt with salt marsh vegetation
The latter study compared urea and Milorganfie
additions.