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Development of Rhincalanus nasutus (Giesbrecht, 1888) (Copepoda, Rhincalanidae) from the Humboldt Current System
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Morphological changes in the exoskeleton of naupliar stages 2-6 and copepodid stages I-V of Rhincalanus nasutus are described. On the distal segment of naupliar antennule, one lateral seta and two medial setae are added during each molt to nauplius 3-6. A naupliar arthrite is a thick, distinctive structure on the coxa of antenna, and the exopod of this limb is patterned from the large proximal segment of that ramus. The coxal gnathobase of the mandible appears at nauplius 4. Buds of maxillule and maxilla are added during the molt to nauplius 5, and buds of maxilliped and swimming legs 1-2 are added during the molt to nauplius 6. The somite bearing maxilla clearly articulates completely with the somite bearing the maxilliped on the last two naupliar stages. This unusual articulation does not appear during copepodid development, and the somite bearing swimming leg 2 is the anterior articulating somite during this later phase. One articulating somite is added during molts to copepodid II-V. Segmentation of the antennule is completed by copepodid IV. Segmentation of the exopod of antenna does not change during the copepodid phase, but one segment is added to the endopod of maxilla. Segmentation and setation of the maxilliped follow the usual calanoid pattern. Buds of swimming legs 3-5 are ventrolateral on their somite. Their presumptive exopod has two attenuations; their presumptive endopod bears an attenuation and a seta. Segmentation of the rami of swimming legs 1-4 follows the common pattern for copepods except for the exopod and endopod of swimming leg 1 which are only 2-segmented.
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Seasonal variability in food consumption, body composition and allometric relationships in the brown shrimp Farfantepenaeus aztecus (Ives, 1891) (Decapoda, Penaeidae) from Tamiahua Lagoon, Veracruz
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The effect of salinity and temperature regimes, typical of most contrasting periods of the annual cycle (warm and cold) at Tamiahua lagoon, Veracruz, Mexico, on food consumption, body composition and allometric relationships of juveniles of the brown shrimp Farfantepenaeus aztecus (Ives, 1891) were examined. The following morphometric and tissue composition parameters were measured: total length (TL), cephalothorax length (CL), wet weight (WW), dry weight (DW), % body water content, organic matter (OM), total minerals (TM) and energy content (EC). The digestive tract of shrimps collected from both warm and cold periods was analysed determining its composition, quantity, and caloric content of the ingested food. Allometric relationships were calculated among: DW-WW, WW-TL and CL-TL. OM and TM content were correlated with the shrimp’s body weight. During the cold and warm seasons, salinity fluctuated between 24 and 36 psu and 12-36 psu, and average temperatures between 25 and 30°C, respectively. WW-TL and CL-TL relationships were statistically different among shrimps from both seasons. Body water content varied significantly, altering the DW-WW relationship, being higher in the warm season. No significant seasonal variation was detected in the shrimp’s OM, TM and EC. A shift in shrimp feeding habits was distinguished in the two seasons examined. Carnivorous habits prevail in winter whilst herbivory is more frequently observed during the warm season. However, the food energy remained relatively stable in both seasons, indicating that shrimp consume available resources in the lagoon in order to compensate for the absence of other food components and thus to maintain a constant energy flow independent of the season.
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Pollicipes pollicipes (Gmelin, 1789) (Cirripède, Lepadomorphe) : étude de la croissance et de la dynamique des populations dans la région de Mirleft (sud ouest Marocain)
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Pollicipes pollicipes (Gmelin, 1789) (a stalked barnacle) is illegally exploited by the human population of Mirleft, because of its commercial value. Accordingly, considering the current concern for the conservation of the species, we carried out a monthly monitoring programme, within our larger scale study on the population dynamics of P. pollicipes, during the period April 2009-April 2010 at three sites in the region of Mirleft (Morocco): Grizim, Imin Tourgua and Sidi Mohamed Ben Abdellah. The results suggests that (1) recruitment occurs throughout the year at the three sites studied, and the intensity of this process shows temporal and spatial fluctuations; (2) the populations are very heterogeneous and contain various age classes; (3) the population density and biomass are low in relation to protected habitats; (4) pairwise comparison of parameters (wet weight/total length; dry weight/rostral-carinal length; rostral-carinal length/total length) shows a significant correlation; suggesting that these parameters vary in concert; (5) the growth rate of this species shows some variation among the site ( K = 0 . 450 at Grizim, K = 0 . 460 at Imin Tourgua, and K = 0 . 410 at Sidi Mohamed Ben Abdellah).
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Effects of temperature on survival, growth, reproductive and life span characteristics of Branchinecta orientalis G. O. Sars, 1901 (Branchipoda, Anostraca) from Iran
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Branchinecta orientalis G. O. Sars, 1901 is a common inhabitant of seasonal water catchments in the northwest of Iran. Hatching, growth, survival, and reproductive characteristics of this species were studied at different temperatures in the laboratory. The Cumulative Hatching Success was significantly higher for specimens cultured at 21°C (85.27 ± 12.21%) compared to those hatched at 12, 15 and 27°C ( P < 0 . 05 ). Hatching started on the same day (48.00 h after inundation) at temperatures of 21, 24 and 27°C), whereas this took more time at lower temperatures, slowest at 12°C (126.00 ± 0.58 h after inundation). The initial hatching fraction was the highest at 21°C (44.60 ± 18.69%) and lowest at 12°C (9.10 ± 8.28%). Total length was significantly longer at high temperatures, 12.38 ± 0.71 mm at 27°C, compared to 4.07 ± 0.42 mm at 12°C on day 15. Nevertheless, contrasting results were obtained for survival, being the lowest at 27°C (22 ± 4.00%) and highest at 12°C (93.07 ± 2.08%) on day 15 of growth. The animals reached sexual maturity significantly faster at 27°C (9.38 ± 1.09 days) compared to all other treatments. A significantly longer life span was detected at 12 and 15°C (63 days), and the higher cyst production at 18°C, compared to other experimental conditions ( P < 0 . 05 ).
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Distribution and reproductive pattern of deep-water crangonid shrimps in the East Sea of Korea
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In this study, we investigated the distribution patterns of two crangonid shrimps in the East Sea of Korea. The distributions of the shrimps differed significantly with depth. Neocrangon communis (Rathbun, 1899) was found at depths of 300-900 m throughout the survey area, with the greatest number of individuals at 300 m depth in the total sampling period. Argis toyamaensis (Yokoya, 1933) occurred over the entire depth range (300-900 m), with the greatest numbers of individuals at 800 m depth in the total sampling period. On average, the large females and ovigerous females of N. communis and A. toyamaensis were mainly distributed in shallow waters (300-400 m depth). The ovigerous females of the shallow-dwelling species N. communis mainly occurred in shallow waters. The deep-dwelling species, A. toyamaensis, differed slightly from N. communis in terms of the distribution of its ovigerous females. The ovigerous females of A. toyamaensis were widely distributed at all depths, and the gonadosomatic index did not differ significantly with depth. However, the deep-dwelling species, A. toyamaensis, had larger eggs than had N. communis. We suggest that life-history strategies are determined by many environmental factors, including depth, in the deep-water environment. The optimal distribution depths of these two species were closely related to their reproductive strategies.
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Identification and molecular characterization of a chitin binding-like protein from Fenneropenaeus chinensis (Osbeck, 1765)
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In this study, a chitin-binding-like protein was cloned and characterized from Fenneropenaeus chinensis (Osbeck, 1765) and named as FcCBP. The results indicated that the full length DNA of 2098 bp with four introns, had an open reading frame encoding a polypeptide of 190 amino acids. The calculated molecular mass of the mature protein was 20.2 kDa and the theoretical pI was 5.93. The FcCBP shared a conserved ChtBD2 domain (amino acids 83-154) with six conserved cysteines (33, 75, 85, 124, 127 and 138). A phylogenetic analysis of CBP sequences showed that FcCBP had low homology with the CBPs from other invertebrate groups. qRT-PCR analysis indicated that FcCBP was expressed in intestine, hepatopancreas, muscle, and gill tissues, and its profile was increased significantly post WSSV (White Spot Syndrome Virus) challenge in the hepatopancreas and gills, followed again by a decreasing trend. These results indicate that FcCBP might be involved in the immune defense response to WSSV in F. chinensis.
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Occurrence of Amphibalanus amphitrite (Darwin, 1854) (Cirripedia, Balanidae) on Crocodylus acutus (Reptilia, Crocodylia) in Colima, Mexico
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Review
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