The Ecology of Tijuana Estuary, California: An Estuarine Profile

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Table 1. Locations and history of weather records for environmental stations within the Tijuana River watershed (Figure 7). - - Eiev Evaporation Ratntall Station Cat Long 111 records records UNlTED STATES Morend Dam 3241 11631 938 1916-1983 1906-1983 Barr~lt Darn 32 41 116 40 495 1921-1983 1907 1933 Lower Ot~y Darri 32 31 1 16 56 156 1950 1983 1406- 1903 MEXlCO S,in Juan cle D~os 32 59 1 16 00 1 280 1956 1983 1956 1983 Vallt3 Retlondn 3331 11645 242 1939-1942 1938 1983 "-" - --- - 1 946- 1 983 -- - Although ra~nfali patterns influence the rntertrdal port~ons of the estuary, temperature and sallnlty data for channel waters show that the subtrdal habltats are much less vanable (Table 2) Whon Tijuana Estuary IS open to tidal flushing, monthly water temperatures vary only slightly, and water salln~ties change prlmarlly wlth major river flows The ramfall data for San Diego extend back to 1880 and tndicate that perrods of relatrve drought were ~nterrupted by wet years In 1883. 1921, 1940, 1951. 1978, 1980, and 1983 Ra~nfall patterns differed greatly for each of those years In some years, there were summer storms 15 cm of ram foil at Chula Vtsta In August 1977). in some years there were wtnter droughts (almost no rain fell from late December 1983 through summer of 1984) Agatn, the factors most important to the estuary are not necessarily annual rainfall totals. Rather, from recent studies of estuarine dynamics, the amounts and tlmes of ralnfall and streamflow withln the ent~re Tijuana R~ver watershed appear to be crtt~cal The extremes of wet and dry years are apparent in the frequency histogram for ramfall years (F~gure 8) and In the high coefflc~ent of vartation (438';b). Table 2 Mean temperature ('(2) and electrical conduclfvtty fmmho/cm, a measure of salinity; sea water IS approx. 50 mmhos/cm) at Winfield's (1 980) ttdal creek $ampltng stations in T~juana Estuary. Data for two stations are averaged. .-" ---- - ---- Temperature Conductivity Date rinod Ehb Flood Fbb Annual Rainfall tcm) '3 i" 78 14 18 no datd rto data Ftgure 8. Histogram of annual rainfat! for San Diego 4fSi78 18 20 57 63 flindbergh Field) 1880-3984. Mean annuaf rainfall for - -- - --- - - -----.-- this period = 25.7 cm (n = 105).
2.3 LAND USE HlSPQWV Through exami!lation of maps. p~ofographs. and historicai recsrds, i! as been possible lo identify critical events that have shaped iijuar~a Estuary. The physiography of 1985 differs substantiaily fi-om that of the eariies! maps and air photos The many cha~ges in land use reflect aititudes about the la.ndscape. T!ie estuary has been used and abused by a var!e!y of hunan activities These dis?u:bances hav~ inlensilied the effects of riatiiral catasiroph~c elients. The 1904 rsiap (Figure 6') of southwestern California si.ioinls Tijiianri Estuary as having a minar bay and ;a bro;ici !mouth Thc Tijuans River has two channe!~. one near the southern bluffs that border Mexico and another due east of the mouth An isolated, iand-locked iagoon IS iocated - in !he northeastern part of the estuary I hese tniee features persist to date, but in highly modified form. The ear!iesl aeria! photographs of Tijuana Estuary were taken in ihe 1920's. The history of adjacent land uses and their irnpaci on ',he estuary become apparent on inspection of the condition of the river mouth, barrier dunes, cihanne! edges. high rnarsh habitats. wetiand-upland transitions. inland lagoon. and the adjaceni up!and. By 1928 !Figure 9a!, Imperial Beach had been settled with more than 50 dweiiings, most of which were within 3 blocks of the beach. Several roads were present 61gu.e 9 The 3928 aerial photograph of Tijciana Estuary ffrav Courtly of San Die~o1. Pafief a shows ttie ~orthecn arm of the estuary paqel b show.; the central embaynsenf fEt Note dune \regetatton EDV) mudflats (MI adcrng tidai chawels lsiands i!l ~tliand Eag0o.r !hi and dredged channel (DC)
Page 1 and 2: June 1986 I THE ECOLOGY OF TIJUANA
Page 3 and 4: The findings in this report are not
Page 5 and 6: CONVERSION TABLE Metric to U.S. Cus
Page 7 and 8: Page 4.5 Energy Flow ..............
Page 9 and 10: Number Page The channel fish cornrn
Page 11 and 12: ACKNOWLEDGMENTS The California Sea
Page 13 and 14: Figure 1. Lacatlcrn of 71juana Estu
Page 15 and 16: Figure 3. Map6 of Tijuana Estuary s
Page 17 and 18: FI(I(uPc$ 4. Wei&rahOt@ patt@rns of
Page 19: also limitrng Hot, dry desert winds
Page 23 and 24: The nearby bridge remained, and ext
Page 25 and 26: flushing until mid-December 1984. E
Page 27 and 28: with seawater. Even in years with s
Page 29 and 30: flats ~n winter but not in midsumme
Page 31 and 32: Each "island" of higher topography
Page 33 and 34: The vegetation and soils of the upp
Page 35 and 36: populations (Massey 1979) The brrds
Page 37 and 38: c~n~entrations of insects, especial
Page 39 and 40: Frgufe 29. The Ifght-footed clapper
Page 41 and 42: Figure 30. During winter (above) th
Page 43 and 44: anlmal footprints, In the hardpan f
Page 45 and 46: Tijuana Estuary salt marsh Such exp
Page 47 and 48: Frgura 36 The etraracrel an& tidal
Page 49 and 50: ^_ _I __"___I _-a_. -- fable 7. Inv
Page 51 and 52: Pre- 1980 (excluding Hosrner Rehse
Page 53 and 54: Table 8. Average density (number/m2
Page 55 and 56: changes in envlronment has not been
Page 57 and 58: was dominated by goby species, Cali
Page 59 and 60: compared the ,chthyoplankton commun
Page 61 and 62: Figure 43, Birds of the intertidal
Page 63 and 64: -" and that the community was compo
Page 65 and 66: Willet (1 73) i - Water Depth (cm)
Page 67 and 68: Table 14. Early information on dune
Page 69 and 70: Figure 48. Birds that nest on the s
Page 71 and 72:
CHAPTER 4 ECOSYSTEM FldNCTlONlNG St
Page 73 and 74:
were no? irght-saturated untri expo
Page 75 and 76:
Table 17. Conceptual model of chann
Page 77 and 78:
Table 19. Net aboveground productiv
Page 79 and 80:
_I___ I__-~--- 4.4.1 Nitragen Fluxe
Page 81 and 82:
i i t 1 1 I Table 22. Standing crop
Page 83 and 84:
calculated from chlorophyll a measu
Page 85 and 86:
Dissolved Organic Biomass Carbon De
Page 87 and 88:
CHAPTER 5 THE ROLE OF DISTURBANCES
Page 89 and 90:
Table 25. Changes in elevation in t
Page 91 and 92:
Table 26. Change in pickleweed cano
Page 93 and 94:
Table 27. Occurrence (in circular 0
Page 95 and 96:
perennials can survive long periods
Page 97 and 98:
An experiment was designed to deter
Page 99 and 100:
CHAPTER 6 MANAGEMENT CONSIDERATIONS
Page 101 and 102:
Closely associated with the researc
Page 103 and 104:
c. Dredging at Tijuana Estuary will
Page 105 and 106:
Table 30. Predicted impacts of redu
Page 107 and 108:
footed clapper rails; the picklewee
Page 109 and 110:
overwashas, and slabiiizatran rs rl
Page 112 and 113:
REFERENCES Allen, L.G. 1980. Struct
Page 114 and 115:
Minsky, D. 1984. California least t
Page 116:
30272 -101 REPORT WUMENTATION 1. RE
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The Ecology of Tijuana Estuary, California: An Estuarine Profile

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