Development of thermal stratification and destratification scaling concepts. Volume 1: Definition of thermal stratification scaling parameters and experimental investigations

The dimensionless parameters associated with the thermal stratification and pressure history of a heated container of liquid and its vapor were examined. The Modified Grashof number, the Fourier number, and an Interface number were parameterized using a single test liquid, Freon 113. Cylindrical test tanks with spherical dome end caps were built. Blanket heaters covered the tanks and thermocouples monitored the temperatures of the liquid, the ullage, the tank walls, and the foam insulation encapsulating the tank. A centrifuge was used for the 6 inch tank to preserve the same scaling parameter values between it and the larger tanks. Tests were conducted over a range of Gr* values and the degree of scaling was checked by comparing the dimensionless pressures and temperatures for each scaled pair of tests. Results indicate that the bulk liquid temperature, the surface temperature of the liquid, and the tank pressure can be scaled with the three dimensionless parameters. Some deviation was, however, found in the detailed temperature profiles between the scaled pairs of tests

First year growth in the lithodids Lithodes santolla and Paralomis granulosa reared at different temperatures

The southern king crab, Lithodes santolla Molina, and stone crab, Paralomis granulosa Jacquinot, inhabit the cold-temperate waters of southernmost South America (southern Chile and Argentina), where stocks of both species are endangered by overfishing. Recent investigations have shown that these crabs show life-cycle adaptations to scarcity of food and low temperatures prevailing in subantarctic regions, including complete lecithotrophy of all larval stages and prolonged periods of brooding and longevity. However, growth and development to maturity are slow under conditions of low temperatures, which may explain the particular vulnerability of subpolar lithodids to fisheries. In the present study, juvenile L. santolla and P. granulosa were individually reared in the laboratory at constant temperatures ranging from 3–15 °C, and rates of survival and development through successive instars were monitored throughout a period of about nine months from hatching. When the experiments were terminated, L. santolla had maximally reached juvenile instar IV (at 6 °C), V (9 °C), or VII (15 °C). In P. granulosa the maximum crab instar reached was II (at 3 °C), V (6 °C), V (9 °C), or VII (15 °C). The intermoult period decreased with increasing temperature, while it increased in successively later instars. In consequence, growth rate showed highly significant differences among temperatures (P<0.001). Growth-at-moult was highest at 9 °C. Rates of survival decreased significantly in juvenile P. granulosa with increasing temperature. Only at 15 °C in L. santolla, was a significantly enhanced mortality found compared with lower temperatures. Our results indicate that juvenile stages of L. santolla and P. granulosa are well adapted to 5–10°C, the range of temperatures typically prevailing in subantarctic marine environments. In spite of causing higher mortality rates, higher rearing temperatures (12–15 °C) should accelerate the rates of growth and maturation, which may be favourable for projects aiming at aquaculture or repopulation of overexploited king crab stocks

Estacionalidad de larvas de Brachyura y Anomura (Crustacea Decapoda) en el Canal del Beagle, Argentina

This is the first study in the Beagle Channel that reports the larval seasonal distribution, abundance and duration of the larval stages of Anomura and Brachyura, on the basis of a fortnightly sampling programme. An identification key to the specific level of zoeal stages is included. Between September 1987 and March 1989, 304 plankton samples were taken by means of oblique hauls from the bottom to the sea-surface. Eighty-five percent of the samples were taken shallower than 60 m depth. Decapod larvae occurred only in spring and summer. All but two taxa showed a single cohort of larvae which emerge at the beginning of the spring. A second cohort of Munida spp. and Halicarcinus planatus also occurred during summer. The most abundant taxa were Munida spp. (312 larvae ? 10 m-3), Peltarion spinosulum (288 larvae ? 10 m-3),), H. planatus (143 larvae ? 10 m-3),) and Pagurus spp. (79 larvae ? 10 m-3), which represented 97% of the total larvae collected. Larvae of Pinnotheridae, Eurypodius latreillii, Libidoclaea granaria, and Paralomis granulosa were about an order of magnitude less abundant. Relative abundances of larvae correspond to relative abundances of the respective benthic stages. The absence of certain larval stages or of certain species (Acanthocyclus albatrossis and Lithodes santolla) probably indicates their differential distribution within the Beagle Channel. Particularly, lithodid larvae may have benthic or epibenthic habits.En este artículo se presenta la distribución estacional, abundancia y duración de los estadios larvales de los Anomura y Brachyura presentes en el plancton del Canal del Beagle, Argentina, sobre la base de muestreos quincenales. Se incluye además una clave para la identificación de los estadios zoea al nivel taxonómico de especie. Entre septiembre de 1987 y marzo de 1989, se tomaron 304 muestras de plancton, la mayoría provenientes de lances oblícuos desde el fondo hasta la superficie del mar. El 85% de las muestras se tomaron a < 60 m de profundidad. Las larvas estuvieron presentes sólo en primavera y en verano. Todos los taxa excepto dos presentaron una cohorte que provino de la eclosión de los huevos que ocurrió a comienzos de la primavera. Munida spp. y Halicarcinus planatus presentaron también una segunda cohorte durante el verano. Los taxa más abundantes fueron Munida spp. (312 larvas • 10 m-3), Peltarion spinosulum (288 larvas • 10 m-3), H. planatus (143 larvas • 10 m-3) y Pagurus spp. (79 larvas • 10 m-3), y representaron el 97% de las larvas recolectadas. Las larvas de Pinnotheridae, Eurypodius latreillii, Libidoclaea granaria, y Paralomis granulosa fueron aproximadamente un orden de magnitud menos abundantes que las anteriores. La abundancia relativa de las larvas se corresponde aproximadamente con la abundancia relativa de los estadios bentónicos de los respectivos taxones. La ausencia de ciertos estadios larvales o de ciertas especies (Acanthocyclus albatrossis y Lithodes santilla) podría ser debida a una distribución diferencial de las larvas de anomuros y braquiuros dentro del Canal del Beagle. En particular, debido a la ausencia de las larvas de Lithodidae en el plancton se plantea la hipótesis de que sean bentónicas o epibentónicas

Egg development, hatching rhythm and moult patterns in Paralomos spinosissima (Decapoda: Anomura: Paguroidea: Lithodidae) from South Georgia waters (Southern Ocean)

Larval release, hatching rhythms and moult patterns were examined in a captive population of the subantarctic lithodid, Paralomis spinosissima from the South Georgia and Shag Rocks region. Larvae hatched throughout the year with the majority of females starting to release larvae at the end of the austral summer and beginning of autumn. Larval release continued over a period of up to 9 weeks with high variability in the numbers that hatched each day. A similar seasonal pattern to hatching was evident in the moulting of females. Intermoult period for two adult females (CL = 63 and 85 mm) ranged from 894 to 1,120 days while an intermoult period for males was estimated to be in excess of 832 days. The results are consistent with other species of Paralomis and are discussed in relation to physiological and environmental adaptations to the cold-water conditions south of the Antarctic Convergence

Potencial reproductivo de los litodidos Lithodes santolla y Paralomis granulosa (Anomura, Decapoda) en el Canal del Beagle, Argentina

Lithodidae is the only group of reptant decapods that occurs in Antarctic waters and has been particularly abundant in the Beagle Channel, Straits of Magellan and south to 50º S. Because of their abundance in coastal waters, the sympatric Lithodes santolla and Paralomis granulosa have constituted a mixed fishery since the 1930s. The two species differ markedly in their reproductive potential. Lithodes santolla is large (maximum size of 190 mm carapace length, CL, and 8 kg weight), has a generation time of 6 yrs., the reproductive cycle is annual and females carry between 5,000-60,000 eggs per female per clutch. In their life span, L. santolla females produce 6 times more eggs than P. granulosa females. Paralomis granulosa is smaller than its relative (maximum 115 mm CL and 1.5 kg weight), and has a slower growth rate, resulting in a generation time of 12 yrs. The reproductive cycle is biennial and females carry between 800-10,000 eggs per female per clutch. Moreover, the reproductive potential of P. granulosa is reduced because an important proportion of the largest and more prolific females of the population do not carry eggs. In other terms, in one generation time of P. granulosa, two complete generations of L. santolla are produced, and compared to other Subantarctic lithodids L. santolla is the most prolific species. The higher reproductive potential of L. santolla probably confers to this species the ability to recover more rapidly from an overfishing situation.Lithodidae es el único grupo de crustáceos reptantes presente en aguas antárticas y ha sido particularmente abundante en el Estrecho de Magallanes, Canal del Beagle y al sur de los 50º de latitud. Debido a su abundancia en aguas costeras, las especies simpátricas Lithodes santilla y Paralomis granulosa han constituído una pesquería mixta desde la década de 1930. Ambas especies difieren en su potencial reproductivo. Lithodes santolla es más grande (tamaño máximo de 190 mm de largo de caparazón, LC, y 8 kg de peso), su tiempo de generacion es de 6 años, el ciclo reproductivo es anual y las hembras llevan entre 5.000-60.000 huevos por puesta. Durante su vida reproductiva, las hembras de L. santolla producen 6 veces más huevos que las hembras de P. granulosa. Los individuos de esta especie son más pequeños (tamaño máximo 115 mm LC y 1,5 kg de peso), y tienen una tasa de crecimiento más lenta, que resulta en un tiempo de generacion de aproximadamente 12 años. El ciclo reproductivo es bienal y las hembras llevan entre 800-10.000 huevos por puesta. Además, el potencial reproductivo de P. granulosa está reducido porque una proporción importante de las hembras más grandes, y consecuentemente más prolíficas, no portan huevos. En otros términos, en el transcurso de un tiempo de generacion de P. granulosa se producen dos generaciones completas de L. santolla. Asimismo, comparada con otros litódidos subantárticos L. santolla es la especie más prolífica, y comparativamente con P. granulosa, su potencial reproductivo más alto la capacitaría para recuperarse más rapidamente de una situación de sobrepesca

Energy reserves mobilization: Strategies of three decapod species

In food deprivation assays, several different responses have been observed in crustaceans. However, studying energy reserves utilization among more than one species during the same starvation period has not yet been performed, particularly to discern whether the responses are due to intrinsic and/or environmental factors. We hypothesize that decapod species with similar feeding habits have the same strategies in the use of energetic reserves during starvation, even though they inhabit different environments. The aim of this study was to compare the energy reserves mobilization of three decapods species (Cherax quadricarinatus, Palaemon argentinus and Munida gregaria) with similar feeding habits, exposed to similar food deprivation conditions. The crayfish, shrimp and squat-lobster were experimentally kept at continuous feeding or continuous starvation throughout 15 days. Every 3rd day, the midgut gland index (MGI), and the glycogen, lipid and protein contents were measured in the midgut gland (MG) and pleon muscle. Palaemon argentinus mobilized more reserves during starvation, followed by C. quadricarinatus, and the last M. gregaria. The starved shrimps presented low MGI, whereas MG showed a reduction in glycogen (from day 6 to 15), lipid (from day 3 to 15), and protein levels (at day 9 and 15) while in their muscle, lipid reserves decreased at days 3 and 6. In C. quadricarinatus, the most affected parameters in the MG were MGI, glycogen (from day 6 to 15), and lipids (at day 12 and 15). In the MG of M. gregaria only the glycogen was reduced during fasting from 3 to 15 days. Even though the three studied species have similar feeding habitats, we found that their energetic profile utilization is different and it could be explained by the habitat, life span, temperature, organ/tissue, and metabolism of the species. Our results may be useful to understand the several different responses of crustaceans during starvation.Fil: Sacristán, Hernán Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; ArgentinaFil: Rodriguez, Yamila Eliana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencia Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Pereira, Nair de Los Angeles. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencia Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Lopez, Laura Susana. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Biodiversidad y Biología Experimental y Aplicada. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Biodiversidad y Biología Experimental y Aplicada; ArgentinaFil: Lovrich, Gustavo Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; ArgentinaFil: Fernandez Gimenez, Analia Veronica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencia Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; Argentin

Differential growth of the barnacle Notobalanus flosculus (Archaeobalanidae) onto artificial and live substrates in the Beagle Channel, Argentina

In the Beagle Channel, southern South America (ca. 55°S 67°W), about 20% of false king crabs (Paralomis granulosa) >80 mm carapace length are fouled with the barnacle Notobalanus flosculus. To evaluate differences in growth rates of barnacles attached to artificial and live substrates, clay tiles were anchored as collectors to the bottom at two different sites in the Beagle Channel in September 1996: in Ushuaia harbour (low currents and high levels of suspended matter) and around the Bridges Islands (strong currents and low level of suspended matter). Another set of collectors was deployed at the same sites in October 1998 to collect barnacles for histological studies. Tiles were removed from each place, approximately, on a monthly basis. Carapaces of P. granulosa with the epizoic N. flosculus were sampled between November 1996 and 1997, and between March 1998 and September 1999, to study sexual maturation of barnacles. Growth of barnacles was compared between the collectors and P. granulosa carapaces following a qualitative approach. A sexual maturity scale was defined, based on the stage of development of the female reproductive apparatus of N. flosculus. Growth rate of barnacles was highest in the harbour, intermediate on P. granulosa, and lowest around the Bridges Islands. Presence of oocytes was registered only in epizoic barnacles, suggesting that at least a proportion of these individuals is able to spawn on the carapaces. The potential advantages of settling on a living substrate, namely increased availability of food particles and decreased predation risks are discussed. © Springer-Verlag and AWI 2005.Fil:Venerus, L.A. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.Fil:Calcagno, J.A. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.Fil:Lovrich, G.A. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.Fil:Nahabedian, D.E. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina

Nuevas localidades para Crustacea Decapoda en la región magallánica, en la América del Sur austral.

We report the occurrence of Lithodes turkayi (Anomura), Libidoclaea granaria, and C. edwardsii (Brachyura), in the Beagle Channel. This observation extends their range of distribution south of the previously reported limit of the Straits of Magellan. Acanthocyclus albatrossis (Brachyura) occurs south of Isla Navarino and also in the Beagle Channel, however in a particular habitat of its northern coast. The occurrence of Lithodes confundens (formerly identified as L. antarcticus) north of the eastern entrance of the Straits of Magellan is also reported. We extend its range of distribution northerly and its bathymetric distribution to the intertidal.En este artículo describimos la presencia de Lithodes turkayi (Anomura), Libidoclaea granaria, y Cancer edwardsii (Brachyura) en el Canal del Beagle, que extienden su rango de distribución al sur del Estrecho de Magallanes. Notificamos aquí la presencia de Acanthocyclus albatrossis (Brachyura) en un único habitat con particulares características de la costa norte del Canal del Beagle. También describimos la aparición de Lithodes confundens (registrado previamente como Lithodes antarcticus) en el intermareal al norte de la entrada oriental del Estrecho de Magallanes, extendiendo su rango de distribución hacia el norte y su distribución batimétrica hasta el intermareal

Las centollas colonizan la Antartida

Es conocido que en Antartida no viven cangrejos. El hallazgo en los ultimo años de centolla podria estar anunciando la futura conquista de la Antartida por los cangrejos