Structural development of Pacific red snapper Lutjanus peru from hatching to the onset of first feeding

Successful rearing of larval fish requires culture conditions and feeding strategies matching the ontogenetic status of larvae. This study describes the external morphology and development of organs and structures involved in the feeding process (i.e. sensorial organs, mouthparts and digestive system) from hatching until first feeding in Pacific red snapper. Hatching occurred 26 h after fertilization at 26°C and total length (TL) was 2.45 ± 0.08 mm. The larvae showed an undifferentiated eye and digestive tract. At 48 hah, TL was 3.31 ± 0.12 mm. Yolk and oil globule were still present. The mouth was still closed, but the Meckel's, quadrate, hyoid and hyomandibular cartilages were present. The retina was formed by 5 layers, and a thin layer of pigment epithelium was observed in the outer nuclear layer (ONL). At 70 hah, TL was 3.44 ± 0.22 mm. A remnant of oil globule was still present. The mouth and anus were open. At 93 hah, the number of cones in the ONL of the retina have increased and there was more pigment in the pigment epithelial layer. A joint between Meckel's and the quadrate cartilage and also a joint between the hyomandibular cartilage and the skull were present. The presence of live feed was detected in the digestive tract of these larvae. Based on these observations, the Pacific red snapper larvae is functional to start ingesting live feed between the 3rd and 4th day after hatching.     

Local and remote physical processes driving variability of the planktonic system in the Juan Fernández Archipelago: A multidisciplinary framework providing conservation insights

1. The Juan Fernandez Ridge, a vulnerable marine ecosystem located far off the coast of central Chile and formed by several seamounts, guyots and three islands (Robinson Crusoe, Santa Clara and Alejandro Selkirk), has recently been declared a Coastal Marine Protected Area of Multiple Uses with several National Parks embedded in it.
2. Recent studies have highlighted the influence of remote and local oceanographic structures on the hydrographic dynamics of this ridge. However, there is still a gap in understanding how they affect the structure and dynamics of the surrounding insular planktonic communities.
3. A hydroacoustic and oceanographic survey was conducted during the austral spring (October 2016), including hydrographic and zooplankton sampling around Robinson Crusoe Island. Oceanographic features were identified and tracked using satellite data (chlorophyll-a (Chl-a) and sea surface temperature) and modelling results.
4. Two events of Chl-a increase relative to a threshold (>0.45 mg m⁻³) were forced by different physical processes, both affecting the western side of Robinson Crusoe Island. In event A during the cruise period, Chl-a subsurface maxima were associated with the arrival of a coastal meander originating on the continental shelf off Chile (remote process); the zooplankton was dominated by copepods and salps, with an evident coastal–oceanic gradient. In event B, Chl-a maxima were linked to a local upwelling forced by the intensification of a localized SSW wind. No influence of remote eddies or local Von Kármán vortices on Chl-a distribution was observed.
5. These findings highlight the influence of remote and local physical processes on the structure of planktonic communities around Robinson Crusoe Island. Understanding the variability of these mechanisms and their effects at the base of the pelagic food web is critical in adopting an ecosystem-level approach.

     

Drivers for spatial modelling of a critically endangered seabird on a dynamic ocean area: Balearic shearwaters are non-vegetarian

1. Spatial modelling is an important research tool to improve our knowledge about the distribution of wildlife in the ocean. Using different modelling techniques (MaxEnt and a generalized linear mixed model), a predictive habitat suitability model was developed for one of the most threatened seabirds in the world: the Balearic shearwater, Puffinus mauretanicus.
2. Models were developed using a 10-year dataset from the Gulf of Cádiz (on the south-western Iberian Peninsula), a key foraging area for Balearic shearwaters during migration and the non-breeding season.
3. Predictive habitat maps strongly matched the observed distribution patterns, pointing to bathymetric features as the main modelling drivers. The species was concentrated on shallow areas (up to approximately 100 m in depth) of the continental shelf, very close to the mouth of the Guadalquivir River. In contrast with previous studies, Balearic shearwater distribution in the highly dynamic Gulf of Cádiz was not correlated with areas of high chlorophyll a concentration.
4. This lack of spatial correlation probably arises from the delay between the phytoplankton bloom and the response of the zooplankton and small fish that are preyed upon by Balearic shearwaters, which may result in important displacements of this trophic chain across the Gulf of Cádiz.
5. The analysis presented contributes to a better understanding of the spatial distribution and ecology of the critically endangered top predator in the Gulf of Cádiz and offers important information to improve management plans.

     

Effects of formalin on total haemocytes count and histopathological changes in the shrimp Litopenaeus schmitti (Pérez‐Farfante & Kensley 1997)

Formalin is used in shrimp industry to eliminate ectoparasites and as a disinfectant. However, the effect of formalin on shrimp's defense mechanism is unknown. Several biomarkers were used to assess the immune response of juveniles of the shrimp Litopenaeus schmitti exposed to different concentrations of formalin (10, 25 and 50 mg L^?1) during 24 and 48 h. Formalin concentrations of 25 and 50 mg L^?1 produced a significant reduction in the total haemocyte count at both 24 and 48 h. Peroxidase and phenoloxidase activity did not show variations. The total protein concentration in haemolymph of shrimps was not significantly different between experimental groups. Histological analysis showed hyperplasia in the gills of animals exposed at 10 mg L^?1 for 24 h; however, the exposure at 25 and 50 mg L^?1 caused necrosis in gills, hepathopancreas and the antennal gland.     

Enhancement of gilthead seabream (Sparus aurata) larval growth by dietary vitamin E in relation to two different levels of essential fatty acids

The objective of this study was to determine the effect of dietary vitamin E on gilthead seabream (Sparus aurata) growth and survival, at two different highly unsaturated fatty acids (HUFAs) levels. Eighteen days old gilthead seabream larvae were fed four formulated experimental diets combining two different dietary levels of HUFAs (M: medium 2.5 + 1.5, DHA + EPA, H: high 5 + 2.5 DHA + EPA g per 100 g) with two different levels of vitamin E (M: medium 540 mg kg^?1, H: high 2900 mg kg^?1): MM, MH, HM, HH (HUFA/vitamin E). After 2‐week feeding trial, the average survival rate was 52.6% and there were no significant differences found among treatments. Increase in vitamin E up to high level markedly improved larval growth, particularly when dietary HUFA levels were lower, suggesting a higher protection value when these fatty acids are more limiting. At medium dietary HUFA levels, increase in vitamin E from medium to high level enhanced larval growth performance in terms of total length. Moreover, increase in vit E enhanced HUFAs content in the larval polar lipids denoting the anti‐oxidative effect of vitamin E.     

Management of limb fractures in wapiti (Cervus elaphus): 22 cases (1993-1997).

OBJECTIVE: To determine treatment and outcome of a series of wapiti (elk) with fractures of the limbs. DESIGN: Retrospective study. ANIMALS: 22 wapiti. PROCEDURE: Medical records were reviewed to determine affected limb and bone, fracture configuration, method of treatment, outcome, and complications. RESULTS: 2 animals had fractures of the humerus; 8 had fractures of the radius, ulna, or both; 5 had fractures of the third metacarpal bone; 3 had fractures of the tibia; 2 had fractures of the femur; and 2 had fractures of the tarsal bones. Most fractures (n = 11) were closed, displaced, nonarticular fractures; 6 fractures were open. Four animals died or were euthanatized prior to fracture treatment, 2 were not treated because fractures had already healed, and 14 underwent fracture repair. In the remaining 2 animals, the affected limb was amputated. Five animals developed nonfatal complications (wound dehiscence, osteomyelitis [2 animals], delayed union, and malunion) and 2 developed fatal complications (gastrocnemius rupture and femoral fracture during recovery). Overall, 16 animals were discharged from the hospital, and all were doing well at follow-up, 2 months to 4 years after discharge. CLINICAL IMPLICATIONS: In wapiti, limb fractures can be successfully treated by means of internal or external fixation. The high rate of fracture healing, even among wapiti with open fractures, should encourage veterinarians to repair limb fractures in wapiti.     

Undernutrition in the parental and first generation provokes an organ‐specific response to oxidative stress on neonates of second filial generation of Wistar rats

Undernutrition induces an increase of the oxidative stress that can predispose offspring to various diseases in adulthood through epigenetic reprogramming. The aim of this study was to evaluate the effects of intergenerational undernutrition on protein oxidation and antioxidant defence response on liver, heart and brain of the second‐generation neonates (F₂) of undernourished rats. For this purpose, both parents in parental (F₀) and first generation (F₁) were fed with a low‐nutrient diet. Body mass and length decreased (p < 0.05) in F₀, F₁ and F₂ being the F₁ males who exhibited a greater mass loss. A decrease in plasma albumin concentration was observed in F₂ neonates (p < 0.05) and also a mass loss of liver, heart and brain (p < 0.05), although proportionally to body length reduction. Undernutrition increased levels of protein oxidation in liver and heart (p < 0.05) but not in brain (p > 0.05) while catalase activity increased only in brain (p < 0.05). In summary, intergenerational undernutrition modifies the antioxidant status through an organ‐specific response, on F₂ neonate rats, where the brain increased catalase activity to prevent a severe oxidative damage and support the vital functions of this key organ to maintain vital functions.     

Evaluation of hepatitis E virus infection between different production systems of pigs in Brazil

The objectives of this study were to (1) investigate the occurrence of hepatitis E virus (HEV) in pigs from large-scale and family-scale farms, (2) genetically characterize the strains isolated, and (3) study the pathogenesis of swine HEV infection via immunohistochemistry. A total of 50 pigs from 10 farms in Mato Grosso State, Brazil were divided according to type of production system into either large-scale farms (n?=?5) or family-scale farms (n?=?5). Samples of liver, gallbladder, small and large intestines, bile, and feces from the pigs were analyzed by nested PCR with primers targeting the ORF2 region of HEV and by immunohistochemistry. Of the eight HEV-positive samples from pigs of family-scale farms, phylogenetic analysis revealed that seven of the swine HEV isolates clustered with subtype 3b of genotype 3 and one isolate was categorized with subtype 3 f. The HEV antigen was detected mainly in the small intestine samples from family-scale farms, suggesting an early stage HEV infection. HEV was not detected in the samples of pigs from large-scale farms, reinforcing the need for additional studies to evaluate the risk of transmission of HEV to humans from pigs from family-scale farms in Mato Grosso State.