Paw Scallop Nodipecten Subnodosus Research Articles

Scope for growth of cultivated Pacific and Gulf of California populations of lion's paw scallop Nodipecten subnodosus, and their reciprocal transplants

In the present work, the relative effects of the season (early vs. late summer), site (Gulf vs. Pacific study sites), the population of origin (Gulf vs. Pacific) and associated abiotic variables were determined in two geographically-separated Nodipecten subnodosus populations and their reciprocal transplants, through the scope for growth (SFG) and net growth efficiency (K2) using a portable open-flow system. Results indicate that both energy acquisition and expenditure were significantly affected by season, site, and population factors. Scallop energy acquisition and growth efficiency were highest during the earlier, cooler part of the summer and higher at the Pacific site where food availability was highest. Significantly higher respiration rates were measured for the Pacific scallop population, leading to significantly lower net growth efficiency than scallops of Gulf origin, which indicates a physiological advantage for Gulf scallops during the suboptimal growth conditions present during summer months on both coasts of the Baja California peninsula. It may have important implications for aquaculture enterprises in this region, and may also confirm the genetic divergence between these two geographically separated populations. The advantages of the open-flow system for in situ ecophysiological studies in aquatic organisms are discussed.

Oregano oil as a therapeutic treatment in the production of mixotrophic larvae of the lion's paw scallop Nodipecten subnodosus

Antibiotics have been used massively for aquatic organism production. However, their use should be limited given the problems of increased antibiotic resistance, and new alternatives should be attempted, such as the use of plants extracts with antibacterial properties. The effect of the essential oil of oregano (Origanum vulgare) compared with three antibiotics (enrofloxacin, florfenicol, and oxytetracycline) on embryogenesis and early larval stages were evaluated to obtain mixotrophic larvae of the scallop Nodipecten subnudosus. Incubation densities of 20 and 100 fertilized oocytes mL−1 were used. The highest yield of normal larvae (calcified D-larvae) occurred at high densities in an order of 300% (36–45 D-larvae mL−1), with the highest values being obtained when the fertilized oocytes were treated with the oregano essential oil and with the antibiotic florfenicol, 44.8 ± 5.16 and 40.9 ± 12.06 D-larvae mL−1, respectively. Nevertheless, the use of florfenicol produced larvae with shorter anteroposterior length, which strengthens the advantage of using oregano essential oil over the antibiotics for spat production of N. subnudosus.

Comparative analysis of the reproductive strategy of lion’s paw scallop Nodipecten subnodosus in Baja California Sur, Mexico

The reproductive strategy of lion’s paw scallop Nodipecten subnodosus was evaluated in a culturing system in Bahía Tortugas, Baja California Sur, Mexico during an annual cycle, comparing its response with data previously reported at other localities. High frequencies of ripe gonads throughout the year indicate that reproduction was continuous, with two main ripening/spawning events: July-September and December-March. A continuous breeding is also reported for the species in Bahía Magdalena, Bahía Juncalito, and Bahía de Los Angeles. These eutrophic areas are Biological Active Centers where gametogenesis appears to be regulated by the energy taken from recently ingested food following an opportunistic strategy. However, the digestive gland index decreased and the muscle indices increased during one of the breeding peaks, suggesting that some stored reserves are also used to sustain gametogenesis (conservative strategy) partially. High incidences of atretic oocytes are likely associated with atypical daily variations in water temperature from May through September (12 to 33°C), or with stressful conditions in the culturing system in summer. Despite this, the culturing system set in Bahía Tortugas appears beneficial for a continuous reproduction of N. subnodosus.

Pycnogonids associated with the giant lion´s-paw scallop Nodipecten subnodosus (Sowerby) in Ojo de Liebre Bay, Guerrero Negro, Baja California Sur, Mexico.

Five species of epibenthic pycnogonids collected on the giant lion´s-paw scallop Nodipecten subnodosus are recorded. A new species of Eurycyde, Eurycyde bamberi, is described. Of the 19 species known in this genus; the new species is closest to Eurycyde hispida Kroyer, 1844 but differs from it in the absence of plumose spines and the shapes of the lateral process, first coxa, and ocular tubercle. The new species represents the third member of Eurycyde from the eastern Pacific in addition to Eurycyde spinosa Hilton, 1916 and Eurycyde clitellaria Stock, 1955. Besides Eurycyde bamberi, the following species were collected: Nymphopsis duodorsospinosa Hilton, 1942c; Callipallene californiensis (Hall, 1913); Nymphon lituus Child, 1979; and Pycnogonum rickettsi Schmitt, 1934. Pycnogonum rickettsi is recorded for first time from Mexican waters, as is Nymphon lituus from the western coast of Baja California Peninsula. Each of these four species are re-described and re-illustrated in order to fill in existing gaps in the literature of the region.

Quality and shelf life of the gonad of lion's paw scallop transported and stored whole in refrigeration

The effect of refrigerated 48h transport and 4 days storage on the quality and shelf life of the whole lion's paw scallop Nodipecten subnodosus gonad was evaluated. Proximal composition, adenosine 5´triphosphate (ATP) and related products, K-value, total volatile bases (TVB-N), trimethylamine (TMA-N), pH, fatty acid profile and microbiological analyses were quantified. Gonad holds a significant composition of essential fatty acids while levels of gonadal ATP were initially low; moreover, K-value of the gonad remained constant. With respect to TVB-N and TMA-N, only the former exceeded allowed limits. The pH level showed no significant variation during storage and, despite the high level of TVB-N, according to the TMA-N as well as microbiological analyses it was demonstrated innocuity after 4 days under the transportation and storage conditions utilized.

Effect of seasonality and storage temperature on rigor mortis in the adductor muscle of lion's paw scallop Nodipecten subnodosus

The effect of season and storage at three temperatures (0, 5 and 10°C) was evaluated on the main metabolites and parameters related to rigor mortis. Adenosine 5′-triphosphate (ATP), lactic acid, octopine, pH and sarcomere length in the adductor muscle of lion's paw scallop Nodipecten subnodosus were determined. Seasonality influenced the initial values of ATP, octopine and pH, however, no effect was noticed during storage, since a similar effect for the three temperatures evaluated in the four seasons was observed. A lower ATP concentration was found during storage at 0°C than that found in muscle stored at 5 and 10°C. According to the analyses of lactic acid, octopine and pH, the muscle acidification during rigor mortis was independent of lactic acid production. The greater sarcomere lengths for all seasons were in agreement with the highest ATP concentrations, corresponding to the samples stored at 5 and 10°C. Therefore, according to the level of myofibrillar contraction, rigor mortis was lower at 5 and 10°C storage in the four seasons. Hence, it is concluded that the seasonality did not show a significant impact on metabolite and parameter values related to rigor mortis during storage, and that 5°C is the best storage temperature for the adductor muscles during the initial stage of rigor mortis and then reduce it to 0°C, if it is focused to the fresh market.

Identification of a tubulin-α gene specifically expressed in testis and adductor muscle during stable reference gene selection in the hermaphrodite gonad of the lion's paw scallop Nodipecten subnodosus

For non-model species, as many used for aquaculture, with minimal or no genomic information, relative quantification of gene expression studies requires preliminary research including the isolation of potential reference genes and the identification of those stably expressed under the biological conditions of interest. Here we report on the isolation of five partial gene sequences from gonad tissue cDNA in the functional hermaphrodite scallop Nodipecten subnodosus to be evaluated as reference genes: 18S-rRNA, riboprotein l8 (rp-l8), actin-β (act-β), elongation factor 1α (ef-1α) and alpha-tubulin-α (tub-α). We found that 18S-rRNA was stably expressed independently of the priming method used to reverse transcribe RNA to cDNA, oligo-dT or random hexamer. Stability analysis for the five putative reference genes with geNorm and NormFinder indicated that 18S together with rp-l8 were the most stable genes for normalization of gene expression during gonad development in both, male and female sexual regions of the hermaphrodite N. subnodosus. The least stable gene was tub-α, showing a biased expression profile between sexual regions of the gonad, therefore this gene was analyzed thereafter as a target gene together with vitellogenin (vit) and a DEAD-box RNA helicase (dbx) gene. Relative expression, estimated by normalization with the combination of 18S and rp-l8 as reference genes, indicated that as gonad development advanced two of the target genes were up-regulated, tub-α in the male region and vit in the female region. Whereas an increased expression was expected during development for vit for its known role in vitellogenesis, the increased expression of tub-α in the male sexual region was unexpected, and pointed toward this gene being a testis-specific α-tubulin isotype. Further analyses of gene expression among tissues indicated that tub-α is specifically and highly expressed in the male gonad, although expression in adductor muscle was also observed at significantly lower levels. The existence of testis specific α- and β-tubulins has been previously reported in other taxa, relating their function to sperm axoneme formation. Tissue-specific tubulin genes, particularly their promoters, have recently found an application as native promoters for transgene tissue-specific expression in research and reproductive control of insect plagues. The third target gene, a putative member of the DEAD-box RNA helicase family (dbx), showed no changes in expression during gonad development or between sexual regions, therefore it was chosen to discuss the different statistical inferences resulting from the arbitrary use of ‘randomly chosen’ reference genes when normalizing gene expression.

Effect of emerged shipment on the physiological condition of the adductor muscle in adult giant lion's paw scallop Nodipecten subnodosus (Sowerby 1835)

Currently, there is an increasing interest in shipping live adult scallops to markets and broodstock to hatcheries; nevertheless, information about the shipping effect on live scallops physiology is very scarce. In a previous study, a method in emersion was developed to ship scallop seed out of water, but it was not known whether this method is useful to transport adult organisms. As a consequence, the purpose of this study was to evaluate the effects of transportation by the emersion method on the physiological status of the adductor muscle of adult giant lion's paw scallop. Live specimens were packaged in a container and transported in emersion for 11 h. Six scallops were frozen in a farm and a similar number were frozen as soon as they arrived to the laboratory. Physiological indices were determined in each lot and the survival was estimated 24 h after re-immersion. As a result of the transportation, a significant loss (P<0.05) of total carbohydrates, glycogen, adenosine 5′-triphosphate and adenilated energetic charge, and a significant increase (P<0.05) in the free amino acids concentration were observed. Eighty-eight per cent survival was achieved; therefore, we conclude that this method is appropriate for shipping live adult scallops of Nodipecten subnodosus.

Larval abundance and spat collection of the lion’s paw scallop Nodipecten subnodosus in Ojo de Liebre Lagoon, Baja California Sur, Mexico

Large numbers of spat of giant lion’s paw scallop Nodipecten subnodosus are required for the development of the scallop aquaculture industry. Despite the large adult populations of this species in Ojo de Liebre Lagoon, Baja California Sur, Mexico, attempts to collect spat with onion bag collectors during the reproductive season (September–November) have not been successful. We assessed lion’s paw spatfall at three sites (La Ventana, El Conchalito, and El Borbollón) within the lagoon, where high recruitment was previously recorded. Netlon collectors instead of onion bags were used and they were deployed at each site at a depth of 1 m on two occasions (October and November 2007) when pediveliger larvae were more abundant. Collectors were retrieved and evaluated in February 2008, after being submerged for 118 or 82 days. Pediveliger larvae were present from late September to late November at all three sites. Densities peaked at 1 m in mid-November and were significantly higher at La Ventana, accounting for 12,400 larvae m–3. Collectors installed in October at El Conchalito showed higher (P &lt; 0.05) mean recruitment (1.7 ± 0.2 spat per collector) than collectors set in November (0.4 ± 0.3 spat per collector). Collectors installed in October and November at La Ventana had 0.6 ± 0.3 and 0.9 ± 0.2 spat per collector, respectively. No significant differences were observed in the growth rates of the juveniles collected. High densities of larvae in the plankton during November indicated that high reproductive activity occurred earlier that month or in late October. La Ventana showed the highest potential for spat collection based on larval abundance, followed by El Borbollón and El Conchalito; however, El Conchalito showed the highest spat recruitment, followed by La Ventana and El Borbollón. Since spat collection was relatively low at all sites, more efforts to determine better collection sites and techniques, as well as appropriate deployment times are required.

Growth and reproduction of the lion's paw scallop Nodipecten subnodosus in a suspended culture system at Guerrero Negro lagoon, Baja California Sur, Mexico

The lion's paw scallop, Nodipecten subnodosus (Sowerby) has considerable aquacultural potential due to its fast growth and large adductor muscle. Prior investigations throughout northwestern Mexico's littoral have reported highly variable growth rates; furthermore, no studies are available of the environment on growth and gametogenesis in this species under culture conditions. This investigation assesses the effect of food availability and temperature on the growth and gametogenesis of N. subnodosus in a suspended culture system at Guerrero Negro lagoon, Mexico. After 1 year of cultivation, N. subnodosus reached 69.13 mm in shell height (SH) (0.196 mm day−1, 14 months old). Two significant growth spurts were observed: over the two first months of culture (August and September 2001, mean growth rate 0.4 mm day−1) and in September 2002 (0.3 mm day−1), both related to high temperatures and chlorophyll a concentrations. The onset of gametogenesis occurred in April 2002, with an increase in temperature (10-month-old scallops, 54.5 mm SH). The first spawning occurred in October and November (86.2 and 93 mm SH), with peak temperatures. These results, together with the analysis of previous reports, indicate that N. subnodosus has a higher preference for temperate areas; therefore, the Guerrero Negro lagoon appears to be a suitable site to culture this species.

Effect of algal diet and temperature on survival, growth and biochemical composition of spat of the lion's paw scallop Nodipecten subnodosus

To find the best conditions for production, spat of the scallop Nodipecten subnodosus were grown for 10 weeks at 23, 26 or 29 °C, and fed with 2:1 mixtures (cell:cell) of Chaetoceros calcitrans with Pavlova lutheri or Isochrysis sp. (diets M1 and M2) or with a 1:1 mixture of P. lutheri and Isochrysis sp. (diet M3). Mortality was 100% after 4 weeks at 29 °C. Survival was significantly higher with diet M1 than with the other diets, and was 51 and 46% at 23 and 26 °C, respectively. With diets M2 and M3, the respective percentages of survival were 39.39 and 33.84% at 26 °C and 23.03 and 19.85% at 23 °C. The best growth in shell height was with diet M2, but there were no differences in final organic weight between diets M1 and M2; diet M3 gave the lowest spat growth. The highest protein content was with diet M1 at 23 °C. This diet gave the lowest carbohydrate contents of the spat at both temperatures, and the lowest spat lipid content at 23 °C. The fatty acid composition of spat was related to that of the respective diets, and there was no evident relation between dietary fatty acids and spat growth. Our results indicate that N. subnodosus spat should be kept at 26 °C and fed a mixed diet containing C. calcitrans and either P. lutheri or Isochrysis sp.

Monoamine fluctuations during the reproductive cycle of the Pacific lion's paw scallop Nodipecten subnodosus

The Pacific lion's paw scallop Nodipecten subnodosus has been one of the most important commercial species of mollusc in the Baja California peninsula in Mexico since 1990. This species is a functional hermaphrodite with tropical and sub-tropical distributions and experiences wide annual temperature oscillations influencing its physiological functions. We determined norepinephrine (NE), dopamine (DA), and serotonin (5-HT) concentrations in different organs (female and male gonads, digestive gland, adductor muscle, gill, mantle, and foot) of N. subnodosus, at 6 reproductive stages (resting, initial, maturing, mature, partially spent and fully spent). Monoamine concentrations were determined by HPLC fitted with an electrochemical detector. Results indicated that monoamine concentrations increased during maturing stage, peaked at mature stage and declined after spawning. NE concentrations were higher than the rest of monoamines followed by DA, and 5-HT. NE was present in all organs at all reproductive stages. DA concentrations were higher in the gill and digestive gland during all stages. 5-HT was only detectable in the male gonadic portion at all stages except at spent stage. NE was the most abundant neurotransmitter found in the female gonad of N. subnodosus, while 5-HT was the most abundant neurotransmitter found in the male gonad. Furthermore, these two neurotransmitters accumulated in the respective gonad tissues during the initial reproductive stages I to IV and then declined after spawning (stages V and VI). This suggests that this species utilized different neurotransmitters specific for each gender and that this utilization was related to the reproductive cycle.

ALINITY TOLERANCE AND RESISTANCE OF THE PACIFIC LION'S PAW SCALLOP (NODIPECTEN SUBNODOSUS) AND THE RELATIONSHIPS WITH SPECIES DISTRIBUTION AND DENSITY IN A COASTAL LAGOON

Abstract Salinity tolerance and resistance of the Pacific lion's paw scallop Nodipecten subnodosus, using the median lethal concentration method (LC50) and a gradual change method were measured. We also attempted to demonstrate whether salinity and temperature, pH, dissolved oxygen and turbidity control the distribution and densities of species within a coastal lagoon (Laguna Ojo de Liebre, Mexico). The upper and lower LC50 of this scallop were determined in the laboratory at predetermined times over 4 days (96 h) when exposing specimens to salinities of 15, 20, 25, 30, 37, 42, 47, 50 and 60 ppt. The upper and lower salinity resistances were studied by subjecting the specimens to either increases or decreases of salinity by 3 ppt every 3 days, departing from a normal salinity of 37 ppt. Salinity, temperature, pH, dissolved oxygen, and turbidity of the water close to the bottom were measured once a month from January 2001 to March 2004 at 20 stations located along the shore of the lagoon. Results showed no...

Lipid composition of the giant lion's-paw scallop ( Nodipecten subnodosus) in relation to gametogenesis : I. Fatty acids

Seasonal variations in fatty acid composition in several tissues of a 1-year-old population of giant lion's-paw scallop Nodipecten subnodosus were analyzed during gonad development. Samples were taken bimonthly from December 1999 to June 2000, a period in which gonad development was occurring. Fatty acid accumulation in neutral and polar lipids of the female gonad was concomitant to the gonad development and presented a maximum in June. Among essential fatty acids, a specific accumulation was observed only for 20:5 n − 3 in the female gonad, as suggested by an increase in its proportion in the neutral and the polar fractions. However, no specific accumulation was observed for 22:6 n − 3, as its proportion remained relatively constant in both fractions. We suggest that a specific increase of 22:6 n − 3 is not necessary during gametogenesis because its proportion was high enough for reproductive purposes (20–30%). Although some data suggest a partial mobilization of polyunsaturated fatty acids from the muscle and digestive gland to the female gonad during gonad development, the main supply came directly from the diet. The maximum increase in total and specific fatty acids in the digestive gland occurred in April and was maintained in June. These changes reflect either a higher lipid availability of the food, or the beginning of storage process in the digestive gland. However, in the female gonad, the maximum increase was observed in June, whereas gonad development and spawning were observed from April. It is suggested that different patterns of lipid accumulation in the first (April) and second (June) maturation processes could be related to the reproductive cycle of this species, which exhibits an initial facultative maturation during spring and the main reproductive activity during summer.