In this study, changes in digestive physiology and nutritional reserve content during the early stages of the Pacific pygmy octopus, Paroctopus digueti, were examined. Body growth, biochemical ...composition (soluble protein and glycogen concentrations) in the digestive gland and arm muscle, hepatosomatic index, as well as lipases and proteases (acid and alkaline) activities were determined every two days up until 14 days after hatching. Newly hatched octopuses were obtained in the laboratory, from the eggs of a female that spawned in the wild and were kept in individual chambers and fed fresh crab meat. A significant decrease in soluble protein was observed in both, the digestive gland (8 days after hatching) and the arm muscle (2–4 days after hatching). Thereafter, soluble protein gradually increases in digestive gland whereas, in the arm muscle, afterward a significant increase at 6 days after hatching, a decreasing pattern until 14 days after hatching was noticed, possibly due to the start of exogenous feeding. In arm muscle, 2 days after hatching the glycogen showed a peak with subsequent marked fluctuations up to 14 days after hatching, indicative of the complete use of internal nutritional reserves and dependence on exogenous feeding at this time. Higher lipase activity was observed 2 days after hatching, with a significant decrease occurring between 6 and 14 days after hatching. Acid protease activity increased between 6 and 14 days after hatching, while alkaline protease activity remained stable during the developmental period, with a peak occurring 8 days after hatching. These results contribute to the further understanding of this critical period of transition from endogenous to exogenous feeding that takes place between 6 and 8 days after hatching and may be useful in developing effective feeding schemes employing natural or formulated foods for this species.
•Biochemical and metabolic changes occurring the first 14 days prepare and increase the digestive capacity of juveniles.•A steady increase in protease activity after 6 DAH reflects the maturation of the digestive gland.•An increasing lipase activity during the first 6 DAH suggests high lipid utilization from the yolk sac internal reserves.•The transition from endogenous to exogenous feeding occurs between 6 and 8 DAH.•Changes in the activity of the acid and alkaline proteases indicates a predominantly acid digestion.
The fishery for octopus in Northwest Mexico has increased to over 2,000 tons annually, but to date the specific composition of the catch has been ignored. With at least three main species targeted by ...artisanal fisheries in the region with distinct life histories, the lack of basic biological information about the distribution, metapopulation size and structure of each species could impede effective fisheries management to avoid overexploitation. We tested if different life histories of three species of octopus could help predict observed patterns of genetic diversity, population dynamics, structure and connectivity and how this information could be relevant to the sustainable management of the fishery. We sequenced two mitochondrial genes and genotyped seven nuclear microsatellite loci to identify the distribution of each species in 20 locations from the Gulf of California and the west coast of the Baja California peninsula. We tested five hypotheses derived from population genetic theory based on differences in the fecundity and dispersal potential for each species. We discovered that
with low fecundity and direct development (without a planktonic phase) had lower average effective population size and genetic diversity, but higher levels of kinship, population structure, and richness of private alleles, than the other two species. These features indicated limited dispersal and high local recruitment. In contrast,
and
with higher fecundity and planktonic phase as paralarvae had higher effective population size and genetic diversity, and overall lower kinship and population structure than
. These observations supported higher levels of gene flow over a larger geographical scale.
with the longest planktonic paralarval duration and therefore larger dispersal potential had differences in the calculated parameters possibly associated with increased connectivity. We propose
is more susceptible to over exploitation of small, isolated populations and could have longer recovery times than the other two species. This species may benefit from distinct fishery management within each local population.
and
may benefit from fishery management that takes into account metapopulation structure over larger geographic scales and the directionality and magnitude of larval dispersal driven by ocean currents and population connectivity among individuals of each locality. The distribution of each species and variations in their reproductive phenology is also important to consider when establishing marine reserves or seasonal fishing closures.
Although octopuses are in high-demand globally and can bioaccumulate high concentrations of metals, the risk associated to its consumption is poorly understood. We compiled literature data from eight ...locations in Europe, North America and Northern Africa with different environmental levels of metals to evaluate: (1) the risk to human health through consumption of muscle tissues and digestive glands of
Octopus hubbsorum, O. vulgaris
and
Eledone cirrhosa
, and (2) the maximum allowable consumption rates (CR
lim
). The assessments were done according the United States Environmental Protection Agency. The results indicate the absence of health risk through consumption of muscle tissues, and high health risk through consumption of digestive glands (attributed to its high Cd levels), reflected in its 1ow CR
lim
values. In conclusion, even in contaminated sites the consumption of octopus muscle tissues is not an issue of concern, while the consumption of digestive glands should be more carefully monitored to avoid health problems.
The gonadal maturation of Atrina maura was examined by means of histological analysis and quantitative criteria. Particular features not previously described for this species are reported in this ...study: in both males and females the undifferentiated stage is absent and there is massive gamete resorption when the seawater temperature reaches 25 degree C; in males, there is continuous spawning concurrent with other gonadal development stages and the adipogranular cells surrounding the acini walls decrease with testis ripeness, which suggests they play an energetic role. Atresia displayed two stages: cytoplasmic structures with oocyte degeneration and digestion by hemocytes. The oocyte diameter was larger than that reported for cultured specimens. Size at first maturity was reached at 23.3 cm in shell height (SH) (12.2 cm in shell length, SL) in females and 22.8 cm SH (12.0 cm SL) in males.
Cultivation of whiteleg shrimp (
Litopenaeus vannamei) is now entirely based on closed life-cycle populations, yet few studies have analyzed gonadal development in domesticated shrimp during grow-out ...in ponds. To determine the effect of age and weight on morphometric, histological, and biochemical variables associated with male and female gonadal development, shrimp from the same cohort, at ages of 6, 8, 10, and 12
months were examined using body weight as a covariable in an ANCOVA design. An additional comparison between two grow-out conditions in 1-year-old shrimp was done to separate the effect of size as a result of initial stocking densities. Age-related growth of gonads was clearly dependent on somatic growth for females but not for males, although differential somatic growth produced by stocking densities explained differences in growth of gonads for both sexes. Increase in oocyte diameter and differentiation associated with age and grow-out condition were independent of body weight. Age-related female gonadal development was accompanied by increases in lipid and protein concentrations, independent of body weight. Maturation of male reproductive organs (testicle, vas deferens, terminal ampoule, and spermatophore) was sequential and depended mainly on age, although body weight could explain differences caused by different grow-out conditions. An age-related decrease in concentration of lactate occurred in all male reproductive organs and could indicate a metabolic adjustment of sperm anaerobic metabolism and lactate clearance associated with gonadal development. We highly recommend waiting for optimal reproductive potential of females at 12
months to enhance spawning frequency and larval quality. At this age, body weight seems to be of secondary importance, although optimal conditions of cultivation are necessary to have adequate growth and balanced nutrition.
The successive stages of oogenesis and the changes involved in the oocyte degeneration process in the penshell Atrina maura were examined using light and transmission electron microscopy. The ovarian ...maturation process is asynchronous, as oocytes at different developmental stages can be found simultaneously. Oocytes develop from oogonia and then undergo three distinct stages of oogenesis: previtellogenesis, vitellogenesis and postvitellogenesis with mature oocytes. Atrina maura displays a solitary oogenesis type, in which follicular cells become associated with oocytes from the earliest stages of development and seem to play an integral role in vitellogenesis. The cytoplasm of vitellogenic oocytes contains numerous whorls of rough endoplasmic reticulum and Golgi bodies, suggesting that auto-synthetic vitellogenesis may occur in this species. In addition, the degeneration process of postvitellogenic oocytes triggered by a seasonal increase in water temperature (> 25°C) is described.
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.
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