| Solenaia oleivora (Bivalvia:Unionidae) is a rare endemic freshwater mussel in China. As its distribution range is relatively narrow, previous research on S. oleivora is very limited, particularly on the reproductive traits that are important characteristics of the life history of freshwater bivalves. This thesis describes the morphological characteristics, reproductive traits, and feeding habits of S. oleivora in the Tianmen River, Hubei province, China. These data are essential to improve our understanding of S. oleivora reproductive biology and construct future management plans for stock breeding, conservation and resource enhancement of this species. The main results were summarized as follows:1. Four hundred and sixty-two mature individuals of S. oleivora were collected from the Tianmen River and their morphological characters were observed. The shell length (L) ranged from77.8mm to176.4mm, shell height (H) was from13.3mm to35.5mm, and shell width (W) was from8.0mm to25.5mm. Individual Shell length was about5.22times as shell height. The relationships between shell length and shell height, shell width were linear correlation and the equations of correlation were L=2.0466+4.3611H (r2=0.7544, P<0.001) and L=4.8863+4.7180W (r2=0.6018, P<0.001) respectively. The age distribution of S. oleivora in Tianmen River was1+～4+years old, and the2+～3+year old individuals were dominant, accounting for84.4%. The relationship between body weight (Wb) and shell length and that between body weight and shell height were power function correlation, the equations of correlation were Wb=0.025523×L286256(R2=0.8052, P<0.001) and Wb=3.22815×H2.72642(R2=0.7154, P<0.001), respectively.2. The results of reproductive biology research showed that S. oleivora was dioecious. Both gills (inner and outer) were used as marsupial to brood the young. Females and males of S. oleivora reached sexual maturity at an early age,1+year old. For mature females, the minimum shell measurements are77.8mm for length and8.41g for weight, and for males these values are87.8mm length and10.01g weight. The sex ratio (number of females:number of males) was1.023:1, which was consistent with the expected ratio of1:1. Gonad development was divided into5stages-proliferating, growing, maturing, spawning and resting. S. oleivora had a tachytictic brood and spawning occurred from February to May, with a single spawning peak in April and May. The fecundity ranged from0.297M to4.079M eggs of each female with an average of1.715M eggs of each female, and fecundity was related to shell length and body weight by a power function. The relative fecundity ranged from0.230M to1.126M eggs of each gram female gonad with an average of0.645M eggs of each gram female gonad. The glochidia of S. oleivora were brown, with small size and semi-elliptical shape, without hook. There were deep or shallow pits on the shell surface of glochidia. There were small thorns closely packed on the ventral margin of the shell, extending to the hinge. The glochidia had larval thread, of which the outer thread was2-5times of shell length. Each glochidium was observed to have four pairs of sensory hairs, three pairs of them were triangularly arranged at the ventral margin of the shell, and the other pair were near to the hinge and parallel with it.3. Observations of stomach content showed that S. oleivora had a certain selectivity for food and its food composition varied with the biomass of food organisms in the water. S. oleivora mainly filter-fed phytoplanktons belonging to Bacillariophyta, Chlorophyta, Cyanophyta, Euglenophyta, Pyrroptata and Chrysophyta. It also fed a few protozoa, rotifers and organic detritus. |
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