Calculation of Habitat Preference Curves of Cryphiops caementarius in the Tambo River, Arequipa - Peru; for ecological flow determination

Abstract

In holistic methods for calculating the ecological flow, two groups of data are required, the
hydrotopographic data of the river to be studied and the habitat preference curve of an
indicator species; In the case of the rivers of southern Peru, the indicator species considered
is the river shrimp Cryphiops caementarius; on the other hand, there is interest in knowing
details of the habitat of the mentioned species due to its ecological, economic and social
importance; That is why it is proposed to determine the habitat preference index of
Cryphiops caementarius in the Tambo River, and from these to calculate and construct the
habitat preference curves. For this, 1810 individuals of C. caementarius are captured. At
the capture points, the depth, the total velocity, the focal velocity, and the type of substrate
are determined; obtaining from this information the habitat use indices. On the other hand,
in the same sampling area, 45 transects are established through the river considering the
most representative areas (tablazos, rapids, backwaters, etc.), in them we proceed to take
measurement of depth, total speed and substrate in a total of 349 points; With this
information, the habitat availability index is determined; Then, by relating these two indices
(index of use / index of availability) the index of habitat preference is obtained, with which
the preference curves are constructed. The resulting values obtained show that a higher
frequency of individuals of C. caementarius prefer depth between 0.20 and 0.40 m;
Regarding the preference of total speed, a higher frequency is observed at 0.11 m / s,
however, a uniform distribution is observed between 0.4 and 1.5 m / s and within the
substrate there is a preference for "edges" (rocks between 64- 256 mm).