Report of Gammarus parthicus in the east of Iran (South Khorasan, Birjand) along with the frequency distribution of body length and the relationship between the number of eggs and different parts of the body

Abstract

Introduction: The goal of this study was to investigate in Gammarus parthicus,
body length frequency distribution (male, female) and relationship between clutch
size and different body parts (head, pereon, pleon).
Materials & Methods: Sampling from a Qanat in 2019 was done in Birjand city
(Spring, Summer, Autumn and Winter). Totally, 252 gammaruses were catched. In
each sampling, one hour was attempted to catch gammaruses by a hand sieve with
one mm mesh size. To measure, a stereo microscope and millimeter paper were used
and the samples were photographed. With a petri dish and the plastic talc (placed
over the samples) gammaruses were photographed lively. Length was measured
from the beginning of the head (Rostrum) to the end of tail (Telson). In addition,
head, back and tail length were measured separately. Image-J software was used to
analyze the resulted images.
Results: The mean total length of males and females gammaruses in four seasons
were (Mean±SE) (15.75±1.21) and (12.93±1.43) respectively. Sex ratios differed
according to the seasons. The total body length was obtained as a model of the
explanatory variables including head length, tail length and season. The most sex
ration in spring (1.39) and the lowest one in winter (0.31) were observed
respectively. The total body length was obtained as a model of the explanatory
variables including head length, tail length and season. The number of eggs (clutch
size) per fertilized female was obtained by tearing the bag of eggs. The number of
eggs was counted in a sample of gammaruses after 10 days keeping in the climate
room. The climate room was used to simulate the reproduction conditions. The
number of eggs was obtained as a model of head length and tail length.
Conclusion: The report of Gammarus in the east of Iran and the influence of season
in life cycle of the Gammarus.