1993  Vol. 17  No. 3

Abstract:
Pond culture experiments (1987—1989) and indoor supple-mental experiments showed that the commonly used stocking ratio of 1 grass carp to 3 filter-feeding fish in polyculture systems fails to fully utilize the interspeeifie benefits among the grass carp, silver carp and bighead carp, resulting in a low energy conversion efficiency in the pond system. Because of the low food availability caused by high densities of silver carp and bighead carp, over-fertilization is frequently practised, resulting in deterioration of water quality and diseases and poor condition in the grass carp. Based on the food-supply potential of the feces produced by grass carp, and the energy flow pathyway acting on the filter-feeding fish, the weight ratio of stocked grass carp to filter-feeding fish was adjusted to (1.5—2.5) : 1 Ⅰ. Green plants were used as the major food, supplemented with pellet feeds. The growth rates of major cultured fishes and energy conversion efficiency of the pond were apparently higher than those in ponds using routine culture methods. With no exogenous fertilization and suitable green and pellet feed inputs in accordance with the biological characters of the grass carp, each unit weight of grass carp produced could yield 40—80% of its weight of filterfeeding fishes.
Abstract:
By lowering the water temperature progressively with an LKB thermostatic circulator, we studied comparatively the low temperature tolerance of mud carp (Cirrhina molitorella)and mixed sperm (from grass carp and mud carp or from grass carp silver carp, red common carp and mud carp) inseminated mud carp of the second successive generation. The mixed sperm inseminated mud carp of the successive generation were more tolerant of low temperature than mud carp both in terms of the enduring time at 7℃ and of the low temperature limits for shock and death. However, the improvement is rather limited. We proposed, therefore, the mixed sperm insemination method is unable to improve the mud carp's low temperature endurance below 6℃ and other breeding methods must be explored in order to improve the cold tolerance of this fish more effectively.
Abstract:
The effct of NaHSO3, a photorespiratory inhibitor, on the growth of Anabaena was studied in the laboratory and field. NaHSO3 at concentrations of 1—10μg/ml enhanced the biomass production of the algae. Best results were achieved at concentrations of 2.5 and 5.0μg/ml. NaHSO3 increased the content of chlorophyll a in the algae, but not the content of protein.
Abstract:
This paper describes a comparative study of the activities of the mitochondria ATP ase of the liver cells in Ctenopharyngodon idella. Leuciscus waleckii and Cirrhina molitorella, acclimated to low and high temperatures. Observations were made on the effect of Tween-80 treatment of the mitochondria on the transition temperature in the Arrhenius plot for the activation energy of the mitochondria ATPase. Compared with fish acclimated at higher temperatures, fish acclimated at lower temperatures showed lower transition temperatures in the Arrhenius plots for the activation energy of their mitochondria ATPase. Treatment with Tween80 resulted in decreased transition temperatures. It was suggested that the magnitude of reduction in the transition temperature when the fish are acclimated to a lower temperature is correlated with the fish's capacity of cold-resistence. The transition temperature is related to tolerance to low temperature.
Abstract:
From January, 1987 to January, 1988,292 specimens of Mystus rnacropterus were collect ed from the Fujiang River at Hechuan county, China, around the middle reaches of the Jiangling River. Through the study of species composition and ecology of the parasitic Protozoa of the fish, the following conclusions can be drawn: Ten species of protozoa were found in the fish, belonging to 4 classes, 7 families and 7 genera. Three of them are new species, i.e. Trypanosoma hemibagri sp. nov., Crytobia cheni sp. nov. and Henneguya hemibagri sp, nov., All type specimens are deposited in the Department of Biology, southwest China Teachers University. 1. Trypanosoma hemibagri sp. nov. (Figs. 1—6) The new species is parasitic in the blood of Mystus macropterus. It resembles T. striati Qadri et al., 1955, but differs from the latter in the following aspects. In the new species, form Ⅰ is the smallest in the three forms, and the width of form Ⅲ is larger than that of form Ⅱ. There is no obvious difference in body length between form Ⅱ and form Ⅲ. The flagellum of form Ⅰ is the longest in the three forms. The undulating mebrane of form Ⅰ is the widest in the three forms. The new species has a small blepharoplast. The distance from anterior border of nucleus to anterior extremity of the body is 11.2μm in form Ⅰ, 12.2μm in form Ⅱ , and 11.4 tan in form Ⅲ, much shorter than that in T. striati. 2. Cryptobia cheni sp. nov. (Figs. 7—9) The new species is parasitic in the blood of Mystus macropterus. It resembles Cryptobia (Trypanoplasma) seenghali Wahul, 1985, but differs from the latter in having distinctive longitudinal myonemes and much larger size of the new species. 3. Henneguya hemibagri sp, nov. (Figs. 10—12) The new species is parasitic in the gill raker of Mystus macropterus. It resembles H. vovki Achmerow, 1960, but differs from the latter in the larger size of its light yellow cyst(537—3500μm) and a much thicker sutural ridge on the spore; the two pear-shaped polar capsuties are mostly not parallel and not equal in size. The prevalence is 88.2%for T. hemibagri, and below 34% for the other nine species. The intensity of infestation by the ten species is mild. Statistical analysis shows that corelationship exists between prevalence (P) of some parasitic protozoa and water temperature (T) or total length (L) of the host, i. e, C. cheni: P=0. 7997—0. 0238T, C. cyprini: P=0.79047—0. 02934T, T. nobillis: P=0.2651—0.0082T, P=1. 312976e0.069L, T. domerguei f. latispina: P=—0. 42704+0.07629T—0.0028T2, P=—9.9643+0.8375L, T. parasiluri: P=—1.001+0.170T—0.005T2, T. oinformis: P=—0.3716+0.0811T—0.0025T2, T.hemibagri: p=45.026+3.287L—0.062L2, T. sinesis: P=—2.44+0.49L. There are obvious annual dynamics of prevalence of the parasitic protozoa, except that of T. hemibagri.
Abstract:
A large number of freshwater atyid shrimps were collected from Guangxi Zhuang Autonomous Region by the authors during the past years. The shrimps belong to two genus, Four are described as new, three of which live in the limestone cave. The type specimens of the new speeies are kept in Shanghai Fisheries University. The diagnosis of the new species is given below. Typtdocaridina liui sp. nov. The rostrum is very short and reaches to the extremity of the eyes. The dorsal border bears 6 teeth, five of which are placed on the carapace behind the orbit; the lower border is without tooth. The eyes are egg-shaped and largely degenerated, bear only a few small round dark pigments, which are separated from each other on the outer antero-lateral corner. Unfortunately, the male of this new species is unknown. This new species is named in honour of Prof. R. Y. Liu,Type locality: Paobingyan Cave. Lingui County. Caridina caverrdcola sp. nov. The rostrum is rather wide, and reaches beyond the antennular peduncle; its tip turned upwards. The dorsal border bears 28—36 teeth, 7—10 of which are placed on the carapace behind the orbit. The ventral border bears 20—24 teeth; its distal 1/5 is devoid of teeth. The eyes are well developed, with a globular, well-pigmented cornea. Remarks: The rostral shape and teeth distribution of the new species closely resemble those of Caridina rubella Fujino et Shokita, but the carpus of the 1st and 2nd ehelipeds of the new species is shorter and coarser. This clearly distinguishes the former from the latter. Type locality: Lenggu Cave, Duan County. Caridina guangxiensis sp. nov. The rostrum is very long and slender, andreaches distinctly beyond the antennular peduncle by more than half of its length. The tip is curved upwards. The dorsal margin bears 9—14 teeth, 5—7 of which are placed on the carapace behind the orbit; the distal half is devoid of teeth. The lower margin is serrated, bearing 41—48 teeth. The eyes are well developed, with a globular, well-pigmented cornea. The endopod of the 1st pleopod in the male is kidney-like. The appendix maseulina of the 2nd pleopod is short rod-like. The appendix interna is large, reaching about distal part of the appendix maseulina. Remarks:The rostrum of the new species is very long and slender, the number of teeth on the upper margin is fewer, and there are more teeth on the lower margin. These characters closely resemble those of Caridina gracilirostris de Man, but the new species has no subapical tooth, and more teeth are situated on the carapace behind orbit. These characters differ from those in the latter. Type locality :Dawangshan Cave, Guilin City. Caridina sphyrapoda sp. nov. The rostrum is long, reaching beyond the extremity of the antennular peduncle, its dorsal border bears 16—17 teeth, and the ventral border bears 8—10 teeth. The stylocerite is long and reaches beyond the end of the basal segment of the antennular peduncle. The 2nd segment of the antennular peduncle is about twice as long as the 3rd segment. The endopod of the 1st male pleopod is kidney—like, the inner border is deeply concave and the basal portion bears a tongue—like protrusion,with many long spinules at the extreme portion. Remarks: The rostrum of the new species is long and the teeth are more in number, the stylocerite is long and closely resembles those of Caridina heterodactyla Liang et Yan, but differs from the latter in the following feature: 1. the 2nd segment of the antennular peduncle is about twice as long as the 3rd segment; 2. the dactylus of the 5th peraeopod is longer, and the comb—like spinules are more in number;3, the shape and structure of the endopod of the 1st male pleopod and the appendix masculina are different. Type locality:Longdonghe,Laibin County.
Abstract:
We investigated the effects of copper on the growth and survival of juvenile loach (Misqurnus mizolepis) in flow-through or renewal test with a hardness of 115 mg/L(as CaCO3). tests began using newly hatched loach larvae and were run for 30 days in flow-through test or 16 days in renewal test. The results showed that, in flow-through test, the lowest observed effect concentration (LOEC)for copper, at which significant effects on the survival of the loach were observed, was 41.2μg/L, and the no observed effect concentration(NOEC)was 25.2μg/L. In renewal test, the NOEC and LOEC for copper were 19 and 38μg/L respectively, based on the standing crop.
Abstract:
This paper describes the structure of testis and spermatozoon in the Chinese freshwater catfish, Leiocassis longirostris. The testes are branched into finger-like structures. The posterior portion of the testis is purple and is composed of simple columnar epithelium. This purple portion does not produce or contain spermatozoa. The testis has a lobular type of organization and consists of somatic and germinal cells. The somatic cells in the testis include fibroblasts, boundary cells, Sertoli ceils and Leydig cells. The lobule is composed of cysts and the germinal and Sertoli cells in the cysts. The Leydig cells are located between the lobules. The germinal cells include spermatogonia, spermatocytes, spermatids and spermatozoa. The gamete consists of a head, a mid-piece and a tail. The head is short, round or oval in shape, containing a nucleus but no acrosome. The nuclear fossa is very developed. The tail is very long, containing lateral fins. The spermatozoa have rich saceiform structure and mitochondria in the base of flagellar.
Abstract:
The ultrastructure of the rostral pars distalis of adenohypophysis was examined in Oreochromis nilotica. The rostral pars distalis is mainly composed of adrenocorticotrophic cells, prolactin cells and one non-secretory cell type-stellate cells. The observations on the annual cycle of the structure of pituitary showed that the adrenocorticotrophic cells and prolactin cells become active during ovulation. It is suggested that ACTH secretion may facilitate ovulation and the prolactin cell activity is attached by changes in environmental temperature. In rostral pars distalis, only the prolactin cells receive direct innervation from type B neurosecretory ending. The steUate cells and type Ⅱ pituicytes play an important role in releasing and transfering the secretory granules from the secretory cells. Two means by which the secretory granules are released, exocytosis and diffusion from the secreting cells, are discussed.
Abstract:
Taxonomic studies were performed on ninety-three bacterial isolates from nine species of fish affected by the septicemia and reared in fresh water in Hubei,Hunan, Henan and Guangdong during the period from May to October of 1990 and 1991. Analysing more than one hundred phenotypic characters and mol%G+C of the bacterial deoxyribonucleic acids, these isolates were assigned either to motile mesophilic aeromonad in the genus Aeromonas or to Vibrio fluvialis in the genus Vibrio. In conformity with the Priority of the International Code of Nomenclature of bacteria, these motile mesophilic aeromonads should be Aeromonas punctata(Zimmermann) nom. rev.; Another group of the pathogenic bacteria was similar to Vibrio fluvialis in most physiological and biochemical characteristics, but differs from the previously described V. fluvialis biovar Ⅰ and biovar Ⅱ in their grouth at 43℃, acid production from salicin, utilization of D-gluconate and putrescine, inability to utilizie glutarate and glucuronate, gas production from D-glucose and 47 mol% G+C of the base compositions. Therefore, a new biovar, Vibrio fluvialis biovar Ⅲ. biovar nov. is proposed.
Abstract:
Micro-electrophoreses are analytical techniques available for separating and characterizing RNAs, DNAs and proteins extracted from small amounts of biological materials. Microisoelectric focussing, one kind of micro-electrophoreses, is used for the first time to analyse esterase isozyme of the wild ciliate Carchesiurn polypinum(Linne, 1758), the isozymes of which have not been investigated before. The results of the experiments demonstrate: 1, samples of two colonies of Carchesium polypinum(about 200 zooids) are sufficient for the microfocussing analysis of esterase isozyme; 2, Carchesiurn polypinum separated immediately from the sample collected from Lake Donghu has almost the same pattern of esterase isozyme as the sample which has been kept in the laboratory for 10 hrs at 30℃. Therefore, isozymes of wild ciliates can be analysed by microfocussing.