The Ecology of Tijuana Estuary, California: An Estuarine Profile

Pre- 1980
(excluding Hosrner Rehse Griswolcl Dexter
Hosmer 1977) 1977 1981 1985 1985
CNlDARlA (COELENTERATES)
P~onrila kailrber!
Coryrnorpha pairnn
PLATYHELMINPtiES
Nemcrf~a spp
Sryiochus sp
Turbcllarra spp
WEMlCHOROATA
Saccoqiossus sp
PHORON113A
Plrotants drch~tocla
x
x
x
x
x
In her studres of Iittleneck clams, Srn~th (1974) while C g~gas appears lo be controlled by
corlcluded that size and clensrty ~r~creased wcth c~mpetitfve ~nteraction with the other two species
tncreaslng t~ifal depth She found average due to broad overlap in substrate and food
dttnsrtles us O?rgh as 207i0 25 mh'tn the subtrdal explo~tatlon
areas cornpared to 201025 rn" In the irltert~dal
sotre Shrp cited sed~rnenl grain sve, ternperattire.
salinrly dr~ratrnrl of feeding trrne, and probability of Peterson (1975) took a more general approdch
r~rodat~oii as factors aflec;titig survlvorsiitp of lhls to the study of the benthos at P~juana Estuary and
2r)eclps Increased food ava~lab~l~ty and substrate compared the~r interspecifrc relatrorlships and
stab~irty are also assocrated with deefter water community stabrirty w~th those at Mugu Ldgoon
Calrfornta. 300 km to the north Compdrlng the
subtidal, sandy bottom habitats of the two area:; he
Ntesen j 1969) saf?lllic?d areas near the mouth of found that the dotninant macroinvertebrates each
Trjuano Estridry to characterrze the sand dollar occupied a characteristic depth within the
(Dcndraster ~?xcenirrcus) populat~on Oensit~es at sediments Sand dollars occupied the top few
that tfme ranqcd from 60m2S0.'rn2 with a mean of centrmeters (Frgure 38) and each had most of its
170/m.Y(n lil) Th~s species became (ocaify test exposed to the water column Littieneck clams
~xtinct aftcx storms i.rrrd flootfrng in 1978 lowered were found wrthrn thc top 6 crn Ghost shrirnp and
water salin~tics lts inahil~ty to reestablish appears its obligate cornnas.risal, false mya, occurred
lo bc rerated to rclcufrlng tow salrntties with [nore together at 0-55 crn There was some overlap wtth
frccjuc!nt rrvcr and wastewater flows enterrng the the purple clam, wh~ch was found at 25-55 crrl
estu;iry in rt?csrat year$
The Cal~fornia jackknife clan burrowed up to 60
cm deep Peterson attributed their vertical
separation to cornpet~tion far space, because there
The domlnani crcrstacoat~ in ttle esttlaf~ ihe ltttie segregatton In food utilizat~on All but one
ghost shrfmp, was sttid~ecJ by Hoiinzlak (1977) were scjspensron feeders, thus. they used the same
This species IS of partlcu!as interest because rt was food source, regardless of burial depth
once ccrmrncrerally harvested as fish bait Mosrner
~nvestig;itecf its rijrnp&i:fv~ ;:;kt'sc:ia;ss
with two syrnpatric burrowing shrlrnp of the same Tyuana Estuary and Mugu Lagoon had similar
farntiy Calhanassa gigas and a Upogcbia species daminan! spectes, but densrtles and relatlve
His work suggested that the distribution and abundances were very different (Table 8) The
abundance of C calrfornrensis and Upogeb~a purple ctam and Californra jackknife ciam were
spectes are determined by spec!ftc substrates, much mare abundant at Tljuana Estuary, whrch