Jp. Olowo et Lj. Chapman, PAPYRUS SWAMPS AND VARIATION IN THE RESPIRATORY BEHAVIOR OF THE AFRICAN FISH BARBUS-NEUMAYERI, African journal of ecology, 34(2), 1996, pp. 211-222
Wetlands, dominated by papyrus (Cyperus papyrus), are extensively dist
ributed in east and central Africa. However, the use of papyrus swamps
by fishes is limited to species that can tolerate the low oxygen cond
itions that can prevail in the dense swamp interior. In this study, we
ask whether the patchy distribution of papyrus swamps may contribute
to variation among fish populations in traits related to oxygen uptake
. A series of paired experiments was used to compare the respiratory b
ehaviour of a small water breathing cyprinid Barbus neumayeri from the
dense interior of a papyrus swamp in Western Uganda, to populations f
rom nearby well-oxygenated rivers and streams. The respiratory behavio
ur of the swamp population differed from the other populations. Severa
l lines of evidence suggest that B. neumayeri from papyrus swamps are
more tolerant of low oxygen conditions than populations from nearby ri
ver and stream sites, including lower thresholds for aquatic surface r
espiration in the swamp population, lower gill ventilation rates in th
e swamp population and higher loss of equilibrium in fish from the riv
er/stream sites. This small scale geographical variation in behaviour
among B. neumayeri populations supports an earlier study that document
ed variation in gill morphology among sites that differed in oxygen av
ailability, and supports the significance of papyrus swamps in promoti
ng diversification among populations.