Brackish Water Shrimp Research Articles

Ventilatory behaviour and chloride regulation in relation to oxygen tension in the shrimpPalaemon adspersusRathke maintained in hypotonic medium

Abstract When exposed to gradually lowered PwO2 values, the brackish water shrimp Palaemon adspersus Rathke responds with an increased ventilation rate with maximum around PwO2 70–80 mm Hg below which the rate is rapidly lowered. Heart rate shows a steady decline with oxygen tensions. When PwO2 levels are subsequently increased again, ventilation rate shows a linear increase, but with a clear overshoot effect at PwO2 over 100 mm Hg. P. adspersus haemolymph has in normoxic condition a Cl− value of 408 mM · 1−1 (medium 250–275 mM · 1−1). The chloride of the haemolymph decreased when PwO2 was lowered below ca. 100 mm Hg. At PwO2 80 mm Hg (ca. Pcr) the haemolymph Cl− begins to show a steady decrease to a new, lower and stable value. At still lower tensions haemolymph Cl− decreased more rapidly and after 1–1.5 h Cl− reached isochlorinity in PwO2 25 mm Hg and less. This phenomenon is considered a re-allocation of energy from ion transport to other vital processes with the consequence of a gradual decrease in haemolymph chlorinity.

The respiration during the moult cycle ofCrangon vulgaris(Fabr.) (Crustacea, natantia)

Abstract The respiratory rate of the brackish water shrimp Crangon vulgaris (Fabricius) was found to be lowest in the intermoult stages C - D1, and the rate increased by a factor of 2.5 up to the proecdysis stage DJ and the postecdysis stage A. At the moult (ecdysis) a short and violent outburst of activity when the old exoskeleton was thrown off increased the oxygen consumption still more. The increased respiration before and after ecdysis is explained by a higher permeability which leads to more work in the regulation of the inner milieu of the animal.

Prospects for the Development of Brackish-Water Fish and Shrimp Culture in India

Brackish-water fish and shrimp culture exists in several localities in India, but the total area used was only 10,000 ha in 1968 and might reach 15,200 ha by 1973. Some of this is in paddy fields used alternately for crops.Natural sources of seed (fish fry and shrimp larvae) are used exclusively. Usually these simply enter the ponds from the estuary during high tide periods. Production averages about 200 kg/ha per year.The potential for increasing brackish-water culture is great. Capital requirements are not excessive, and a return of 15% per annum is suggested under average conditions. Development can be encouraged by surveys of suitable areas, by experimental work on capturing and transporting seed, by artificial spawning for the production of fry of the most desirable species, and by pilot projects to test methods of supplementary feeding and other practices.

Observations on Variations in the Male Sex Characters and Their Relation to the Androgenic Gland in the Shrimp Macrobrachium idae (Heller)

AbstractA majority of the males of the brackish water shrimp, Macrobrachium idae, show a hypertrophy in the length of the second cheliped, the length and spinuosity of the appendix masculina and the width of the vas deferens, during the breeding season. Statistical analyses of the measurements of these characters show that this hypertrophy has only very little correlation to the size of the individual, and that the above sex characters have marked variation in a population having the same body length. The hypertrophy of these structures is more linked with the extent of development of the androgenic gland. Also, in such individuals, the androgenic gland shows signs of increased secretory activity as evidenced by increase in size of the cells, vacuolisation of cytoplasm and presence of degenerative areas. It is suggested that there is a direct relation between the secretory activity of the androgenic gland and the hypertrophy of these structures i.e. there is a “cause and effect” relation between the androgenic gland and the primary and secondary sex characters.

Amylase heterogeneity inPalaemonetes varians(leach) (Crustacea, Decapoda)

Abstract Amylase heterogeneity is reported in the brackish water shrimp, Palaemonetes varians. Results from population studies suggest a genetic basis involving four co-dominant alleles. In three populations from the Oresund only two alleles were found. In a fourth population from the inner part of the Roskilde Fjord two additional alleles were detected.

On the solution, mainly by the aid of graphical construction, of a problem in practical hydraulics

Acidic pollution can cause severe environmental consequences annually in coastal areas overlain with acid sulfate soils (ASS). A water quality model was used as an analytical tool for exploring the effects of water management options and other interventions on acidic pollution and salinity in Bac Lieu, a coastal province of the Mekong Delta. Fifty eight percent of the provincial area is covered by ASS, and more than three-fourths (approximately 175,000 ha) are used for brackish-water shrimp culture. Simulations of acid water propagation in the canal network indicate that the combination of opening the two main sluices along the East Sea of the study area at high tide for one day every week in May and June and widening the canals that connect these sluices to the West Sea allows for adequate saline water intake and minimizes the acidic pollution in the study area. On the other hand, canal dredging in the freshwater ASS area should be done properly as it can create severe acidic pollution.