Plínio Soares Moreira

Osmoregulation and respiratory metabolism in brazilian Macrobrachium (Decapoda, palaemonidae)

Abstract 1. 1. The effect of salinity (0, 7, 14, 21, 28 and 35‰) on osmoregulatory capability and metabolic rate in adult Macrobrachium acanthurus, M. heterochirus, M. olfersii and M. potiuna , was investigated at 20°C using a microcryoscope and Warburg respirometer. 2. 2. All species are strong hyperosomotic regulators in freshwater or low salinities (0–14‰) while at high salinities (21–35‰), with the exception of M. olfersii , they are hypoconformers; M. olfersii exhibits a fair degree of hypo-osmotic regulatory capability. 3. 3. Isosmotic points decrease in the sequence M. heterochirus > M. acanthurus > M. olfersii > M. potiuna . 4. 4. For M. acanthurus and M. olfersii , the metabolism-salinity curves assume a dome shape with a high peak at 21‰ S, close to the isosmotic point. For M. heterochirus and M. potiuna , metabolic rates tended to decline with salinity increase. 5. 5. These results are discussed in relation to the distribution patterns of the adult shrimps and to physiological modifications occurring during development.

The effect of salinity on respiratory metabolism, survival and moulting in the first zoea of Macrobrachium amazonicum (Heller) (Crustacea, Palaemonidae)

Survival, duration of intermoult cycle and respiratory metabolism were evaluated as a function of salinity (0–35‰; 25° C) in early zoeae of the cinnamon shrimp, Macrobrachium amazonicum. Zoeae are extremely resistant to salinity, mortality occurring only in fresh and sea-water after several days. Moulting occurs in all salinities, longer cycles being recorded in 0 and 35‰ S. The metabolism-salinity curve is broadly U-shaped between 0 and 28‰ S but declines sharply in sea-water. Such physiological responses characterise the early zoeae as strongly euryhaline and typically estuarine. Data are discussed in relation to the degree of adaptation of the organism to the freshwater biotope and the position of the species within the generic pattern of adaptive radiation.

RESPIRATORY METABOLISM OF MACROBRACHIUM OLFERSII (WIEGMANN) ZOEAE DURING THE MOULTING CYCLE FROM ECLOSION TO FIRST ECDYSIS

The respiratory metabolism of first stage Macrobrachium olfersii (Wiegmann) zoeae was measured at 12 hr intervals with Cartesian diver microrespirometers throughout the 120 hr period from eclosion to first ecdysis. Weight-specific oxygen consumption rates, although slightly higher immediately after hatching, remained constant and did not differ significantly during the first moulting cycle. Larval dry weight decreased from 21.8 to 18.9 µg during this period. There was no evidence of a diurnal metabolic pattern. The moulting cycle was subdivided according to morphological characteristics, based on the degree of cytoplasmic homogeneity, epidermal retraction, and stage of setal development in the telson. Larval metabolism is suggested to be uniform throughout the eclosion—first ecdysis period, in spite of a distinct and divisible moulting cycle.

The effect of salinity on the metabolic rates of some palaemonid shrimp larvae

Abstract The effect of salinity on the metabolic rates (QO 2 ) of the first zoeal stages of the palaemonid shrimps Macrobrachium acanthurus, M. carcinus, M. heterochirus, M. olfersii and Palaemon northropi was measured at 20°C, using Cartesian diver microrespirometers. Salinities of 0, 7, 14, 21, 28 and 35‰ were used for the species of Macrobrachium , 0‰ being excluded for P. northropi . The metabolic rate-salinity (M-S) response curves for M. acanthurus and M. olfersii zoeae I are both broadly U-shaped, showing a marked elevation of the freshwater end of the curve. Macrobrachium acanthurus zoeae have higher metabolic rates than M. olfersii zoeae in all salinities and show a higher range of M-S independence (14–35‰, cf., 7–28‰). Macrobrachium heterochirus and M. carcinus zoeae I exhibit inverted U-shaped M-S curves between 0–35 and 7–35‰, respectively. The metabolic rate of P. northropi zoea I appears to increase with decreasing salinity, reaching a maximum at 14‰ S. These results are discussed in relation to the general distribution patterns of the adult shrimps.

Temperature and salinity effects on the respiratory metabolism of the first zoeal stage of Macrobrachium holthuisi Genofre & Lobão (decapoda: Palaemonidae)

Abstract Oxygen consumption rates of stage I Macrobrachium holthuisi Genofre & Lobao zoeae were measured in 24 different temperature and salinity combinations using Cartesian diver microrespirometers. Metabolic rates varied little with salinity at 15°C while at 20°C a marked elevation occurred in 0 and 35‰ At 25°C, a slight elevation occurred in 0‰; rates remained constant, however, in the other salinities. At 30°C, respiratory rates were similar to those recorded at 25°C except for decreases at 0 and 28‰ salinity. Q 10 values in the different salinities were usually highest between 15 and 20°C. Statistical analyses showed that while both temperature, salinity and their interaction significantly influenced larval respiratory rates, temperature had the more pronouced effect. Larval metabolism is salinity independent over the salinity range encountered in the larval biotope (7–21‰) at temperatures of 15–30°C.

An annotated bibliography of parasitic Isopoda (Crustacea) of Chondrichthyes

This annotated bibliography is an attempt to bring together all available published records on the parasitic isopods of Chondrichthian fishes as a basic reference source. An effort was made to synonymise old names according to the presently accepted scientific names.

Thermal effects on metabolism in selected ontogenetic stages of the freshwater shrimps Macrobrachium olfersii and Macrobrachium heterochirus (Decapoda, Palaemonidae)

Abstract 1. 1. The effect of temperature on the respiratory metabolism of zoeae I, postlarvae and adult freshwater shrimps, Macrobrachium olfersii and M. heterochirus, was examined. 2. 2. Zoeal and adult metabolic responses of both species were very similar, although each stage inhibits a different biotope; postlarval metabolic responses were the most sensitive to temperature variation. 3. 3. Regression analyses indicated that b values ranged from 0.67 to 0.71 for M. olfersii and from 0.70 to 0.73 for M. heterochirus; a values increased with temperature increase. 4. 4. Ontogenetic stages crossing the marine-fluvial interface exhibit markedly different metabolism-temperature response patterns.

The effect of salinity on the osmo-ionic regulation of Macrobrachium carcinus (Linnaeus)

1. 1. The effects of salinity (0, 7, 14, 21, 28 and 35‰) on haemolymph osmotic, Ca2+, K+ and Na+ regulation in Macrobrachium carcinus were investigated. 2. 2. M. carcinus is a strong hyperosmotic regulator in fresh or low salinities (0–21‰), while at high salinities (28–35‰) it is a hypoconformer. 3. 3. Na+ haemolymph concentrations stayed fairly constant in salinities from 0 to 14‰ and increased slightly with the increase in the external sodium ion concentration. 4. 4. K+ haemolymph concentrations increased slightly from 0 to 21‰ and sharply in salinities beyond this range. 5. 5. Ca+ haemolymph concentrations were hyperionic to those of the media in all salinities. 6. 6. These results are compared with those of the Malaysian prawn, M. rosenbergii.

Species of marine Isopoda (Crustacea, Peracarida) from southern Brazil

Some species of marine Isopoda collected in southern Brazil mostly in shallow-water and amongst seaweeds are studied. Five species are discussed and illustrated. A diagnosis is given for each species. Idotea metallica and Synidotea marplatensis are new oc currences for the area, and both have had their geographical range extended to off Rio de Janeiro. The presence of Idotea balthica and Erichsonella filiformis in southern Brazil was definitely asserted. Illustrations of both sexes of Rocinela signata and details about its occurrence in the region surveyed were made.

Bioecologia de crustáceos decápodos, braquiúros, no sistema baía-estuário de Santos e São Vicente, SP: 1. Ocorrência e composição

De junho de 1985 a maio de 1936, foi realizado um programa de pesquisa no complexo baia-estuario de Santos e Sao Vicente, SP. Para a obtencao do material foram utilizadas redes de arrasto de fundo, e de praia, alem de armadilhas. As operacoes de pesca capturaram 14 especies de decapodos brachiuros, por meio de arrastos de fundo; oito com os arrastos de praia; e cinco, no estuario, utilizando armadilhas iscadas, sendo, estas ultimas, todas pertencentes ao genero Callinectes. Callinectes danae dominou nos tres ambientes, seguidos por C. sapidus e Portunus spinimanus que tambem foram abundantes. O numero de femeas foi superior ao de machos para as especies dominantes e, em geral, esse numero foi maior nas amostras da Baia do que nas de Praia e Estuario. O aumento da captura total nos meses de primavera-verao pode estar relacionado com temperaturas mais elevadas da agua e com padroes reprodutivos apresentados pelas especies. Sao apresentadas listas de ocorrencia e abundância das especies capturadas e de parâmetros hidrograficos e operacoes de pesca.