Search

Jellyfish are economically important organisms in diverse countries, carnivorous organisms that consume various prey (crustaceans, mollusks, bivalves, etc.) and dissolved carbohydrates in marine waters. This study was focused on detecting and quantifying the activity of digestive glycosidases from the cannonball jellyfish (Stomolophus sp. 2) to understand carbohydrate digestion and its temporal-spatial variation. Twentythree jellyfish gastric pouches were collected in 2015 and 2016 in the Gulf of California in three localities (Las Guásimas, Hermosillo, and Caborca). Nine samples were in intra-localities from Las Guásimas. Chitinase (Ch), β-glucosidase (β-glu), and β-N-acetylhexosaminidase (β-NAHA) were detected in the gastric pouches. However, cellulase, exoglucanase, α-amylase, polygalacturonase, xylanase, and κ-carrageenase were undetected. Detected enzymes showed halotolerant glycolytic activity (i = 0-4 M NaCl), optimal pH, and temperature at 5.0 and 30-50 ℃, respectively. At least five β-glucosidase and two β-N-acetylhexosaminidase were detected using zymograms; however, the number of proteins with chitinase activity is not precise. The annual variation of cannonball jellyfish digestive glycosidases from Las Guásimas between 2015-2016 does not show significant differences despite the difference in phytoplankton measured as chlorophyll α (1.9 and 3.4 mg/m³, respectively). In the inter-localities, the glycosidase activity was statistically different in all localities, except for β-Nacetylhexosaminidase activity between Caborca and Hermosillo (3,009.08 ± 87.95 and 3,101.81 ± 281.11 mU/g of the gastric pouch, respectively), with chlorophyll α concentrations of 2.6, 3.4 mg/m³, respectively. For intra-localities, the glycosidase activity did not show significant differences, with a mean chlorophyll α of 1.3 ± 0.1 mg/m³. These results suggest that digestive glycosidases from Stomolophus sp. 2 can hydrolyze several carbohydrates that may belong to their prey or carbohydrates dissolved in marine waters, with salinity over-0.6MNaCl and diverse temperature (4-80 ℃) conditions. Also, chlorophyll α is related to glycosidase activity in both seasons and inter-localities, except for chitinase activity in an intra-locality (Las Guásimas). [ABSTRACT FROM AUTHOR]

Worldwide catches of cannonball jellyfish Stomolophus meleagris (Cnidaria: Scyphozoa) have increased during the last years; nevertheless, this species still lacks updated biological knowledge for its management. This research proposes that the individual growth pattern for jellyfish can be estimated in the absence of age readings through cohort follow-up over time and by multi-model inference approach (MMI). Length data were obtained during 2010–2011 in Gulf of California to obtain cohort information using a multinomial analysis and then assign age; growth model selection was based on MMI. Three cohorts were identified and the von Bertalanffy model suitably described their growth. The species has an accelerated growth with a short life cycle; cohorts one and two reached their asymptotic length, and the third one barely reached the length-at-first sexual maturity. Growth variations among cohorts could be explained by their different biological strategies where the first two prioritized asymptotic length and the third one reproduction length. The three cohorts shared a common goal for medusoid phase, which was sexual reproduction. This information could be used for estimating harvest rates or assessing their capacity for redoubling as an invasive population in coastal ecosystems. The proposed methodology may be applied in other jellyfish species around the world. [ABSTRACT FROM AUTHOR]

The trajectory of the cannonball jellyfish (Stomolophus sp. 2) fishery in the central portion of Mexico's Gulf of California is an all too familiar one, consisting of exploration, rapid development, and, as of now, subsequent collapse. As all of the product is exported to markets overseas, buyers have little incentive to conserve local stocks, with jellyfish now exhibiting a global-scale sequential exploitation experienced by many other marine resources. While historical data gaps are often used as excuses for overexploitation after the fact, the emergence of this modern fishery was accompanied by relatively broad research interest; however, recommendations based on sound science were not followed. The resultant paucity of policy goals, regulation, cooperation, compliance, and enforcement has resulted in the mismanagement of a potentially lucrative fishery for future generations. There are always myriad challenges when attempting to manage a nascent fishery with high uncertainty, particularly in a developing country, and this case further highlights the importance of taking a precautionary approach to emerging resource extraction. Multiple prior experiences with similar outcomes should behoove regulators and managers to exhibit extra caution, and yet, sustainability and forethought still appear to be secondary to short-term profits and employment support. Nonetheless, it is perhaps not too late for cannonball jellyfish fisheries in the Gulf of California, and there are opportunities to implement management strategies that promote collaboration, research, and sustainability. This fishery requires a new management regime that embraces adaptive co-management in order to provide benefits to locals, both now and in the future. • Jellyfish are targeted for food exports in Mexico's Gulf of California. • Catches for one of the targeted species have declined, possibly due to overfishing. • Management challenges are complex due to natural and social factors. • Future strategies should include stakeholder collaboration and adaptive co-management. [ABSTRACT FROM AUTHOR]

Studies of population genetic structure in relation to ecological and evolutionary processes are crucial for conservation genetics and particularly for sustainable management of fisheries. However, such knowledge is not always available for the management of fisheries, as is the case of the edible cannonball jellyfish Stomolophus spp. fishery in the Gulf of California, Mexico. The aim of this study is describe the population genetic structure of cannonball jellyfish in the Gulf of California. We used sequences of cytochrome oxidase I (COI) and microsatellite markers in five locations within the Gulf of California and the southern Pacific coast. Both COI and microsatellite markers corroborated the presence of two differentiated genetic lineages in the fishing areas, which diverged around 1.17 Mya: Stomolophus sp.1, distributed in the Golfo de Santa Clara; and Stomolophus sp.2, in the southern region of the Gulf of California and the Pacific coast of the Baja California peninsula. In addition, significant differentiation between the four locations within the lineage Stomolophus sp.2 was found (mean F ST : 0.56 and 0.12 for COI and microsatellites respectively). Our results are consistent with the endemism and phylogeographic break hypotheses proposed for the northern region of the Gulf of California. We proposed that the historical geology and complex oceanography of the Gulf of California might be responsible of this species-level differentiation. Conversely, the population structure within Stomolophus sp.2 could be more related to the life cycle, and particularly due the short larval dispersal stage of cannonball jellyfish in the Gulf of California. [ABSTRACT FROM AUTHOR]