Feeding juvenile Artemia enriched with ascorbic acid improves larval survival in the spiny lobster Jasus edwardsii

Newly hatched Jasus edwardsii phyllosoma were fed unenriched Artemia [endogenous ascorbic acid (AA) concentration of 166 μg g^?1 dry weight (dw)], Artemia supplemented with algae (AA concentration 594 μg g^?1 dw) or with ascorbyl‐2‐polyphosphate (A2P) (AA concentration 11 737 μg g^?1 dw) to examine possible benefits of AA enhancement on culture. Plain or algal‐enriched Artemia were fed continuously for 28 days in two treatments during the study. Four other treatments received A2P‐enriched Artemia on a progressive basis starting from the commencement of the trial (D‐0), the third (D‐3), sixth (D‐6) or ninth day (D‐9) of Stage I (14 days) and similarly during Stage II (14 days). Prior to the commencement of A2P supplementation, plain Artemia were supplied to these animals. By Stage III (28 days feeding), algal, D‐0 and D‐3 phyllosoma had attained the largest size. The uptake and retention of AA by Stage III phyllosoma appeared to be dose‐dependent with the highest concentration of AA incorporation evident in D‐0 phyllosoma (1816 μg g^?1 dw), while algal and plain phyllosoma contained the lowest concentrations (600 and 300 μg g^?1 dw, respectively). Survival at Stage III was highest in D‐0 phyllosoma (89%) and lowest in plain phyllosoma (51%). There was a positive relationship between phyllosoma AA concentration and larval survival (R² = 0.8328, P < 0.0001). D‐0 phyllosoma had the lowest stress index when subjected to an osmotic/temperature activity test, indicative of better survival in culture compared to plain, algal and D‐9 phyllosoma, which had consistently higher indices. A negative relationship existed between phyllosoma AA concentration and stress indices at Stage III (R² = 0.9263, P < 0.0001), suggesting that AA from the Artemia diet conferred stress resistance.     

Effects of salinity and temperature during incubation on hatching and development of lingcod Ophiodon elongatus Girard, embryos

The interactive effects of salinity and temperature on development and hatching success of lingcod, Ophiodon elongatus Girard, were studied by incubating eggs at four temperatures (6, 9, 12 and 15°C) and five salinities (15, 20, 25, 30 and 35 g L^?1). Hatch did not occur in any of the 15°C treatments. Degree days (°C days) to first hatch was not influenced by temperature or salinity, however, calendar days to first hatch differed significantly for temperature (P<0.0001, 61±1, 44±1 and 35±1 days for 6, 9 and 12°C respectively). Degree days to 50% (427.1±4.2) hatch was not significantly influenced by temperature but was by salinity (P=0.0324). Viable hatch (live with no deformities, 74.1±4.0%) was greatest at 9°C and 25 g L^?1 but not significantly different in the range of 20–30 g L^?1. Larval length (9.4±0.13 mm) was greatest at 9°C and 20–30 g L^?1. Temperature and salinity significantly influenced all categories of deformities with treatments at the upper (12°C and 35 g L^?1) and lower limits (6°C and 15 g L^?1) producing the greatest deformities. The optimal temperature and salinity for incubating Puget Sound lingcod eggs was found to be 9°C and 20–30 g L^?1.     

Effects of oxygen supersaturation and temperature on juvenile greenlip, Haliotis laevigata Donovan, and blacklip, Haliotis rubra Leach, abalone

Growth and survival of juvenile greenlip (39.03 (SD 3.80) mm (n=524)) and blacklip (31.92 (SD 4.19) mm (n=531) abalone were investigated at high dissolved oxygen levels (95–120% saturation) between 17 and 19°C. Abalone were fed the same artificial diet and each species was contained in groups of approximately 30 individuals within triplicate tanks for each of six treatments and were exposed to flow through water adjusted to give experimental conditions for up to 75 days. Blacklip abalone held at 16.9°C and 97% oxygen saturation grew in shell length significantly faster than all other treatments of blacklip abalone held at 19°C, and significantly faster than blacklip abalone maintained at 111% oxygen saturation and 17.5°C. Both temperature and oxygen saturation significantly affected the survival of this species. Blacklip abalone held at 19°C had significantly lower survival for both 96% oxygen saturation and 120% oxygen saturation, compared with blacklip abalone maintained at either 110% oxygen saturation and 19°C, or for any 17°C treatment. No significant differences were noted for greenlip abalone within the range tested in terms of growth rate, food consumption rate or survival, indicating that greenlip abalone tolerated these conditions better than did blacklip abalone.     

Body shape variation within and among three species of darters (Perciformes: Percidae)

Abstract –  Using geometric morphometric (GM) techniques, we quantified intra and interspecific variation in female body shape using five collections each of Etheostoma caeruleum Storer, Etheostoma nigrum Rafinesque, and Etheostoma stigmaeum (Jordan). Nested multivariate analysis of variance showed significant variation in body shape among populations (Wilks' Λ = 0.0687, F _144,7585.1 = 19.35, P  < 0.0001), as well as among species (Wilks' Λ = 8.7 × 10⁻⁶, F _24,2 = 28.18, P  = 0.0348). Etheostoma caeruleum displayed greater body depth relative to both E. nigrum and E. stigmaeum , whereas E. nigrum displayed a compressed arrangement of mid-body landmarks relative to both E. stigmaeum and E. caeruleum . The broader implications of these findings highlight the value of geometric morphometrics as both an exploratory and analytical approach. Conclusions drawn from comparisons among moderately differentiated darter species in future studies of body size and shape are likely robust to intraspecific variation within species, and will permit more rigorous investigations into the ecomorphology of these benthic stream fishes.     

Kurokura Solution as Immobilizing Medium for Spermatozoa of Tench (Tinca tinca L.)

This study tested KUROKURA solution (Kurokura et al., 1984, Aquaculture 37, 267–274) and its modifications (by increasing NaCl content to 160, 180 and 200 mM) on immobilizing properties for sampling and short-term preservation of potential motility of tench spermatozoa. The immobilizing solution is used because, when collected, the sperm of most samples is contaminated by urine, causing spermatozoa to be of poor quality, with low motilities and velocities (almost 0), thus resulting in a worsened fertilization and hatching rate. Sperm was sampled with a syringe containing an immobilizing solution (IS), allowing an IS:sperm ratio of 2:1, under aerobic conditions at 0–4°C. This sperm solution was stored for 10 h and untreated sperm was collected prior to fertilization as a control. Spermatozoa quality was evaluated for the cell motility and velocity parameters and also for fertilization ability and hatching rate. Results obtained for tench sperm motility, velocity, fertilization and hatching rate showed that only sperm collected in the various immobilizing solutions can be successfully used for artificial insemination and preservation after 10 h at 0–4°C. The best immobilizing solution was found to be KUROKURA 180 (180 mM NaCl, 2.68 mM KCl, 1.36 mM CaCl₂· 2H₂O and 2.38 mM NaHCO₃), giving a fertility and hatching rate of 41%, with no change in rates after 10 h storage of sperm. Control sperm without immobilizing solution showed a fertilization and hatching rate of only 6–7%.     

The genetic structure of Mytilus chilensis (Hupé 1854) populations along the Chilean coast based on RAPDs analysis

The Chilean blue mussel Mytilus chilensis is an important commercial species. However, little has been published on the population genetics of this species, despite the need to implement management and conservation policies. Randomly amplified polymorphic DNA‐polymerase chain reaction analysis was used to estimate genetic variation within and between eight natural populations along the whole range of its Chilean natural distribution (ca. 1900 km from Arauco (VIII Region) to Punta Arenas (XII Region)). The values of Nei's unbiased genetic distance, D (0.030–0.107), among populations were small, despite the large geographic separation. A mantel test using 50 000 randomizations showed evidence for a significant correlation (r=0.74, P<0.05) between genetic and geographic (coastal) distance. Punta Arenas population was the most genetically differentiated from the others, although the scale of differentiation was not large (D=0.076–0.107). The levels of gene flow (Nm=1.55) found in this study prevent differentiation among populations by genetic drift. This is the result of the long‐lived planktotrophic larvae of M. chilensis, which provides this species with considerable dispersal ability throughout its range, which is favoured by the ocean currents along the Chilean coast. A restricted larval dispersal towards the north due to the Cape Horn Current derived from the West Wind Drift could be the cause of the higher genetic differentiation of Punta Arenas population from the northern populations. For management purposes of the M. chilensis fishery, the results provide no evidence for discrete stocks, with the possible exception of the Punta Arenas population. The present study provides the baseline data in order to continue further characterization of these mussel populations, considering the great increase in aquaculture of this species.     

Quantitative genetic parameter estimates for size and growth rate traits in Pacific white shrimp, Penaeus vannamei (Boone 1931) when reared indoors

Heritabilities of size traits and growth rate traits, as well as genetic, phenotypic and environmental correlations were estimated at three ages for a captive population of Pacific white shrimp (Penaeus vannamei) grown indoors. A covariate, mean size or mean growth rate during early growth in individual tanks before tagging and mixing, was introduced in the analyses to reduce the error caused by unique previous growth conditions on variance components. Heritabilities of size traits increased with age, with the h² for TL, AL, TWt and Wi1AS being 0.15, 0.20, 0.20 and 0.22, respectively, at 17 weeks, increasing to 0.28, 0.33, 0.34 and 0.35 at 29 weeks of age. Heritabilities of growth rate traits estimated between consecutive growth periods decreased from the first (h² for ΔTL 0.65, ΔAL 0.71, ΔTWt 0.63 and ΔWi1AS 0.84) to the second period (h² for ΔTL 0.34, ΔAL 0.50, ΔTWt 0.54 and ΔWi1AS 0.52). Phenotypic correlations were always larger than genetic correlations for both, size and growth rate traits. Genetic correlations between size traits within age were high (r_G >0.95), but those between the same size trait at different ages decreased as the age difference increased in spite of a consistently high environmental correlation (r_E 0.80–0.85) between the same trait at different ages. Phenotypic and genetic correlation's between the same growth rate trait at the two different growth periods evaluated were negative or zero (r_G TL –0.26, AL –0.24, Wi1AS 0.00) with the exception of total weight (r_G TW 0.35) and the environmental correlations between growth periods were also low (r_E 0.13–0.32).     

Alteration of liver and muscle fatty acid composition in gilthead seabream (Sparus aurata) juveniles held at high stocking density and fed an essential fatty acid deficient diet

The aim of the present study was to determine the combined effect of both stress and EFA deficiency on several biological and biochemical parameters. Fish were fed during 15 weeks two isocaloric and isoproteic diets: a control diet based on fish oil and formulated to meet the n-3 HUFA requirements for this species (1.5% of n-3 HUFA) and a deficient diet containing beef tallow and formulated to be deficient in n-3 HUFA. Each experimental diet was evaluated both at high and low stocking densities (10 and 3.2 kg m^–3 of initial density, respectively).High stocking density produced a chronic stress situation with elevation of plasma cortisol levels. It also caused a reduction in hepatosomatic index and liver lipid contents, increasing the oleic acid/n-3 HUFA ratios in the polar lipids. Fish fed the EFA deficient diet at low stocking density showed common deficiency symptoms. High stocking density in fish fed the EFA deficient diet induced a higher degree of EFA deficiency symptoms leading to mortality, liver steatosis, liver lipid deposition, reduced muscle lipid and reduced n-3 HUFA contents, which particularly affected EPA, but not DHA, suggesting a preferential retention of the latter fatty acid, specially in the phosphoglycerides fraction.