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New data on the mesopelagic shrimp community of the Canary Islands region
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During the “ZIFIOCAL 1” cruise, carried out around the islands El Hierro and Tenerife (Canary Islands, NW Africa), at depths between 200 and 750 m, 990 mesopelagic shrimps belonging to 29 species were identified. Many of these species are rare, and therefore the present records constitute new data on their vertical and biogeographical distribution. The collection of Sergia burukovskii represents a new record for the Canary Islands. Finally, the first finding of Ligur ensiferus displaying a pelagic distribution is also reported.
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Sustainable yield of the red swamp crayfish (Procambarus clarkii) through understanding its population structure and dynamics in Poyang Lake
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With increasing commercial demand for its delicacy, Procambarus clarkii has become an important fishery resource of Poyang Lake in recent years. However, habitat loss, overfishing, and the crayfish plague have diminished P. clarkii populations throughout their area of distribution. In consequence, this study systemically analyses the population structure and dynamics of P. clarkii in the wetland of Poyang Lake using the analytical methods of Bhattacharya and Von Bertalanffy. The main purpose was to collect biological data necessary for the management of this species. The present study showed that the population structure consisted of a maximum of 5.58 age classes for females and 3.25 for males, which indicated that P. clarkii is a relatively short-lived species. The Y′/R analysis showed that Epresent > E0.5, which exceeded the optimization (Eopt) criterion of 0.5 for sustainable exploitation of fisheries, so this species was overexploited in Poyang Lake. The Lc (mean length at first capture) equals 67.5 mm. The estimated mesh size for catching the red swamp crayfish is 13.5 cm. The virtual population analysis model (VPA) showed that the largest annual catch of P. clarkii is 3.43 × 104 t. The Maximum Sustainable Yield (MSY) is 1.18 × 104 t. The low natural mortality rate range of 0.68-1.11 year−1 suggested that it is ecologically worthwhile to allow the individuals of P. clarkii to grow to larger sizes in order to contribute to the biomass for biologically optimal exploitation. This could be facilitated by the adoption of measures involving a closed season, which would help to conserve the fishery.
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Temporal variation in the shore amphipod community in the supralittoral zone of Bizerte Lagoon (northern Tunisia)
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Seasonal variation in the structure of the amphipod community on the banks of Bizerte Lagoon was studied at Menzel Jmil (37°13′8″N 09°55′1″E) from July 2006 to June 2007. The distance between the actual sites of collection (sampling points) and the shoreline varied from 70 cm in September to 6.8 m in December. Specimens were mainly collected from under roots of Cymodocea nodosa and Suaeda maritima. In the laboratory, the specimens of Amphipoda (N = 10 645) were preserved in ethanol 70%, identified, sexed, and counted under a binocular microscope. Monthly counts varied between 553 (November) and 1240 individuals (April). Eight species of talitrids were identified, based on the specific characters of their gnathopods and pereiopods. Furthermore, the results show that the amphipod community of Bizerte Lagoon is primarily composed of 3 species, Orchestia mediterranea, Orchestia gammarellus and Orchestia montagui. The species last-mentioned represented the most frequent form in summer, whereas the other two, Orchestia mediterranea and Orchestia gammarellus, dominated in autumn. Orchestia stephenseni, Platorchestia platensis, Talorchestia deshayesii, Talitrus saltator, and Orchestia cavimana, were also found. A subsequent analysis of various diversity parameters of the amphipod community indicated a seasonal variation in abundance, species richness, and diversity.
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Seasonal variations in the length of zooplankton related to certain physicochemical variables in two freshwater reservoirs
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Seasonal variations in the body length of zooplankton were studied in relation to water temperature, nitrate (NO3), soluble reactive phosphorus (SRP), total chlorophyll, Secchi disk depth, pH, conductivity, and oxidation-reduction potential (ORP) in a mesotrophic (Ikizcetepeler) and a eutrophic (Çaygören) reservoir from February 2007 to March 2008. During the study, the body lengths of a total of 7590 zooplankton specimens (1110 rotifers, 3270 cladocerans, and 3210 copepods) were measured. The length of the majority of the species was significantly smaller in summer than in winter, fall, and spring, including that of the most dominant species, Asplanchna priodonta, Daphnia galeata, Daphnia longispina, Diaphanosoma brachyurum, Bosmina longirostris, Leptodora kindtii, Ceriodaphnia pulchella, Cyclops vicinus, Metacyclops gracilis, and Acanthocyclops robustus (F > 5, p < 0 . 05 ). Correspondence analysis (CA) showed that the body length of the zooplankton studied was inversely related to water temperature, whereas it was positively related to ORP and pH. The results of our study suggest that, although nutrients (NO3 and SRP) apparently have an effect on zooplankton body length only in the mesotrophic reservoir, temperature influences the body length in both the mesotrophic and the eutrophic reservoir.
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Distribution and abundance of the pelagic processid, Processa pippinae Wicksten & Méndez, 1985 (Decapoda, Caridea, Processidae), collected during the TALUD XIV cruise in the Gulf of California, Mexico, and description of a new genus
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The pelagic processid, Processa pippinae Wicksten & Méndez, 1985, has been reported previously as an endemic species in the northern Gulf of California, Mexico. Additional material collected accidentally in a benthic sledge and with a mid-water micronecton net is reported, including a series of small-sized specimens (CL 2.2 mm). The shape of the laterally compressed rostrum of this species varies considerably with size and among adult specimens. Based on several morphological characteristics of P. pippinae, a new genus, Maryprocessa, is proposed. Several unique characteristics separate Maryprocessa new genus from the other five genera of Processidae, including the laterally compressed rostrum overreaching the cornea, unique among the Processidae, the extraordinary long antennal and antennular flagella, the posterior lobe on the dorsal margin of the third abdominal somite, and the long, acute pair of spines on the posterior margin of the sixth abdominal somite.
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Seasonal and spatial variations of cladocerans on the northwest continental shelf of the South China Sea
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The seasonal and spatial variations of cladocerans were studied based on samples collected with 169 μm mesh plankton nets from July to August 2006 (summer), December 2006 to January 2007 (winter), and in April 2007 (spring) on the northwestern continental shelf of the South China Sea. Three species of cladocerans (Pseudevadne tergestina, Penilia avirostris, and Podon schmackeri) were observed. Cladocerans occur in spring and summer, but not in winter. They showed an average abundance of 12.82 (± 48.44) inds m−3 in spring and 64.66 (± 188.82) inds m−3 in summer. P. avirostris occurred in the inshore waters of the Leizhou Peninsula during spring, but in summer they were found in large number along the inshore waters from Leizhou Peninsula to the southeast of Hainan Island, with the highest abundance (1121.50 inds m−3). P. tergestina was the most dominant species both in spring and summer, being widely distributed throughout the whole surveyed area. P. schmackeri was distributed mainly along the inshore waters of the Leizhou Peninsula during spring, and mainly along the inshore waters of Hainan Island during the summer (with low density). Our results suggest that the unstable water environment resulting from the strong northeastern monsoon in winter may explain the absence of cladocerans in a large area of the northwest continental shelf of the South China Sea. High chlorophyll a concentration owing to physical factors (e.g., cold eddy, coastal upwelling and mixing) may be the main reason for the difference in the spatial distribution of cladocerans in the subtropical and tropical areas of our survey.
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Brachyuran crabs (Decapoda, Brachyura) associated with the green sponge Amphimedon viridis (Demospongiae) from Itaguá Beach, south-eastern coast of Brazil
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This study provides information on the community structure of brachyuran crabs associated with the green sponge, Amphimedon viridis Duchassaing & Michelotti, 1864, from a beach on the south-eastern coast of Brazil. Monthly collections from May 2002 through August 2003 were carried out on the rocky bottoms off Itaguá Beach (23°27′07″S 45°02′49″W). Crabs on the green sponge banks were hand-caught during snorkelling sessions, and 638 crabs belonging to 31 species, 19 genera, and 10 families were obtained. Biological parameters, including sponge volume, number of individuals, density, richness, diversity, evenness, and dominance changed considerably over time. Species recruitment and foraging habit are some of the factors that drive the richness, dominance, and diversity patterns of this community. The green sponge banks are important sites for recruitment, refuge, and feeding of many species of brachyurans. Therefore, they are also important for the conservation of this group on the south-eastern coast of Brazil.
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Notes on some Indo-Pacific Pontoniinae, LI. Periclimenaeus quadridentatus (Rathbun, 1906) and P. crassipes (Calman, 1939) (Decapoda, Pontoniinae), with the designation of P. calmani and P. serenei spp. nov.
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Further information on the little known pontoniine shrimps, Periclimenaeus quadridentatus Rathbun, 1906 and P. crassipes (Calman, 1939), is provided and illustrated, and Periclimenaeus calmani sp. nov, from the Cobourg Peninsula, Northern Territory, Australia, and P. serenei sp. nov., from Nha Trang, Vietnam, are designated.
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Barnacles (Cirripedia, Thoracica) and associated epibionts from sea turtles in the central Mediterranean
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The association patterns and ecology of sea turtle epibionts, and especially obligate epibionts, are still poorly known. Epibiont communities were investigated in the central Mediterranean Sea in relation to the host habitat and seven species of barnacles, three amphipods, one crab, and one tanaid were found on 117 loggerhead sea turtles, Caretta caretta. Particular attention was given to barnacles, some of them being obligate turtle epibionts, with a total of 3330 individuals examined, among which high intraspecific aggregation was observed. Results indicate that (i) the species composition of barnacles varies among turtles frequenting not only different geographic areas but also different habitats in the same area, (ii) different species have marked preferences for hosts frequenting pelagic vs. benthic habitats, and also (iii) for body parts of the host representing microhabitats with different features and trophic opportunities, (iv) settlement is favoured by the presence of conspecific individuals and possibly also (v) by individuals of related species, notably Chelonibia testudinaria that may act as a pioneer species, and finally (vi) barnacles show rapid turnover on turtles, with relatively short lives, rapid growth, and high juvenile mortality.
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Reproductive biology of Argis lar from the East Sea of Korea (Decapoda, Natantia)
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We studied the reproductive biology of Argis lar from the East Sea of Korea, based on a total sample of 4172 shrimp collected over a 12 month period. The sample included 40 males (size range: 9.91-24.11 mm carapace length, CL), 2797 non-ovigerous females (size range: 7.22-38.33 mm CL), and 1335 ovigerous females (size range: 19.70-37.43 mm CL); size differed significantly among the three groups. Ovigerous females occurred during every month of the year, in varying percentages, with a minimum abundance of 2.48% in August; the extended reproductive period indicates that multiple spawnings occur during the year. All ovarian stages were present in non-ovigerous females, whereas only spent ovarian stages were present in ovigerous females. Two modes were present in the abundances of females at each ovarian stage. In the first mode, females at the mature ovarian stage were most abundant in September (61.98%) and females in the spent ovarian stage were most abundant in November (32.52%). In the second mode, females at the ripe ovarian stage were most abundant in December (62.96%) and females at the spent ovarian stage were most abundant in March (66.00%). The gonadosomatic indices of non-ovigerous females and ovigerous females varied significantly by month. The percentages of ovigerous females with eggs at different stages of development were: non-eyed eggs, 32.06%; eyed eggs, 25.69%; and hatching eggs, 42.05%. Females with hatching eggs occurred from November to June. The relationships between CL and ovary weight differed significantly between ovigerous females with eggs in the non-eyed and eyed stages. Our results indicate that the highest indices of reproductive potential (IRP) occurred in females in the 29.1-31.0 mm CL size class (IRP = 405).
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Tanaidacea (Peracarida) from Macaronesia I. The deep-water fauna off the Selvagen Islands, Portugal
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Three new species of Tanaidacea are described from the Portuguese Selvagen Islands in the Mid-Atlantic, and collected during the EMPC expedition on board the “N.R.P. Almirante Gago Coutinho” in the summer of 2010. The new species belong to the tanaidomorphan genera, Bathyleptochelia, Pseudoarthrura, and Typhlotanais.
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First reports of deep-water hermit crabs Parapagurus Smith, 1879 (Decapoda, Parapaguridae) and coelenterate associates from the Mid-Atlantic Ridge and South Atlantic
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Three species of deep water hermit crabs of the genus Parapagurus Smith, 1879, family Parapaguridae, were collected in the South Atlantic during studies of the fauna and ecology of the Mid-Atlantic Ridge, a seamount chain that is an important habitat, feeding ground, and site of reproduction for many open ocean and deep-sea species. The three species collected, P. abyssorum (Filhol, 1885), P. nudus (A. Milne-Edwards, 1891), and P. pilosimanus Smith, 1879, are known to range broadly in the Atlantic, but only one, P. pilosimanus, was previously reported from the South Atlantic. Thus, P. abyssorum and P. nudus are reported for the first time from the Mid-Atlantic Ridge and the South Atlantic. These three species live in association with zoanthids or actinians that produce carcinoecia and serve as housing. The carcinoecia found with the specimens are also reported.
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Northernmost record of the shamefaced crab Calappa granulata (Linnaeus, 1767) (Brachyura, Calappidae) in the Mediterranean area
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First records of Ergasilus cerastes (Copepoda, Poecilostomatoida) on cage-reared Ictalurus from northeast Mexico
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Importance of models of development for determining homologies
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The isopod Parachiridotea mediterranea Roman, 1991 (Valvifera, Chaetiliidae) in the Ebro delta (Iberian Peninsula)
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Announcement: Changes in style and format
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