M. Castillo-rivera et A. Kobelkowsky, Distribution and segregation of two sympatric Brevoortia species (Teleostei : Clupeidae), EST COAST S, 50(5), 2000, pp. 593-598
The authors described and analysed the temporal and spatial distribution an
d segregation patterns of Brevoortia patronus and B. gunteri, in a coastal
lagoon of Veracruz, Mexico. A total of 394 individuals of B. gunteri (mean
SL of 61.7 mm) and 378 of B. patronus (mean SL of 128.0) were collected, in
189 monthly and 48 diel (24-h cycles) samples. Both species showed two cat
chability peaks-one during March-May (dry season) and the second in July-Oc
tober (rainy season)-and these peaks were related with the two primary prod
uction pulses in the system. These patterns were slightly different for eac
h species, the first peak being more important for B. gunteri (68.6%), and
the second for B. patronus (78.2%). Brevoortia patronus number was correlat
ed with rainfall (P<0.01), and the relative abundance of both species was c
orrelated with salinity (P<0.05). In 24-h cycle analysis, the two species w
ere more abundant around midday (10:00 to 14:00 h), with few individuals ca
ptured during the night, and this behaviour was probably related to light i
ntensity and their trophic activities. Moreover, no diel separation between
species was observed. Spatially, B. gunteri was principally captured (67.4
%) in sites with higher salinities and with no submerged vegetation, and B.
patronus was mainly captured (70.9%) in sites with low salinity and with d
ense beds of Ruppia maritima. Thus, the authors consider salinity as an imp
ortant factor in the seasonal and spatial segregation of Brevoortia species
, with B. gunteri common in periods and zones with higher salinity and B. p
atronus in periods and areas of low salinity. The results presented here su
ggest that these segregation patterns permit resource partitioning between
these species and facilitate their local co-existence. (C) 2000 Academic Pr
ess.