Scyphistomae show different modes of propagation, occasionally allowing the sudden release of great numbers of medusae through strobilation leading to so-called jellyfish blooms. Accordingly, factors regulating asexual reproduction strategies will control scyphistoma density, which, in turn, may influence blooming potential. We studied 11 scyphistoma species in 6 combinations of temperature and food supply to test the effects of these factors on asexual reproduction strategies and reproduction rates. Temperature and food availability increased reproduction rates for all species and observed reproduction modes. In all cases, starvation was the most important factor constraining the asexual reproduction of scyphistomae. Differences in scyphistoma density were found according to the reproductive strategy adopted by each species. Different Aurelia lineages and Sanderia malayensis presented a multi-mode strategy, developing up to 5 propagation modes. These species reached the highest densities, mostly through lateral budding and stolons. Cassiopea sp., Cephea cephea, Mastigias papua and Phyllorhiza punctata adopted a mono-mode reproductive strategy, developing only free-swimming buds. Lychnorhiza lucerna, Rhizostoma pulmo and Rhopilema esculentum also presented a mono-mode strategy, but they only developed podocysts. These 3 species had the lowest reproduction rates and polyp densities; not only their reproduction rates but also the need for a 2-fold set of environmental stimuli to produce new polyps (one for encystment, another for excystment) made this reproduction mode the slowest of those observed to be utilized for propagation. We conclude that blooms may be defined phylogenetically by the specific asexual modes each species develops, which, in turn, is regulated by environmental conditions.

Jellyfish (primarily scyphomedusae) fisheries have a long history in Asia, where jellyfish have been caught and processed as food for centuries. More recently, jellyfish fisheries have expanded to the Western Hemisphere, often driven by demand from Asian buyers and collapses of more traditional local fish stocks. Jellyfish fisheries have been attempted in numerous countries in North, Central, and South America, with varying degrees of success. Here, we chronicle the arrival of jellyfish fisheries in the Americas and summarize relevant information on jellyfish fishing, processing, and management. Processing technology for edible jellyfish has not advanced, and presents major concerns for environmental and human health. The development of alternative processing technologies would help to eliminate these concerns and may open up new opportunities for markets and species. We also examine the biodiversity of jellyfish species that are targeted for fisheries in the Americas. Establishment of new jellyfish fisheries appears possible, but requires a specific combination of factors including high 123Rev Fish Biol Fisheries DOI 10.1007/s11160-016-9445-y abundances of particular species, processing knowledge dictated by the target market, and either inexpensive labor or industrialized processing facilities. More often than not, these factors are not altogether evaluated prior to attempting a new jellyfish fishery. As such, jellyfish fisheries are currently expanding much more rapidly than research on the subject, thereby putting ecosystems and stakeholders' livelihoods at risk.

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We have compiled available records in the literature for medusozoan cnidarians and ctenophores of South America. New records of species are also included. Each entry (i.e., identified species or still as yet not determined species referred to as "sp." in the literature) includes a synonymy list for South America, taxonomical remarks, notes on habit, and information on geographical occurrence. We have listed 800 unique determined species, in 958 morphotype entries: 5 cubozoans, 905 hydrozoans, 25 scyphozoans, 3 staurozoans, and 20 ctenophores. Concerning nomenclatural and taxonomical decisions, two authors of this census (Miranda, T.P. & Marques, A.C.) propose Podocoryna quitus as a nomen novum for the junior homonym Hydractinia reticulata (Fraser, 1938a); Euphysa monotentaculata Zamponi, 1983b as a new junior synonym of Euphysa aurata Forbes, 1848; and Plumularia spiralis Milstein, 1976 as a new junior synonym of Plumularia setacea (Linnaeus, 1758). Finally, we also reassign Plumularia oligopyxis Kirchenpauer, 1876 as Kirchenpaueria oligopyxis (Kirchenpauer, 1876) and Sertularella margaritacea Allman, 1885 as Symplectoscyphus margaritaceus (Allman, 1885).

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For many jellyfish, the magnitude and timing of medusae blooms are recognized to result from the benthic stage dynamics. However, information on the scyphistomae of jellyfish populations in the wild remains scarce. Here, bi-mensual underwater photoquadrat surveys were combined with scyphistomae sampling and observation to describe the annual (February 2017-January 2018) benthic stage dynamics and asexual reproduction strategy of Aurelia coerulea in the Thau lagoon (43°25′31.1″N; 03°42′0.9″E). Our results revealed unexpected seasonal patterns of variation: scyphistoma coverage peaked in the spring (11.6 ± 3.7% on 21st April) and was minimal in the summer and autumn (1.4 ± 1.3% on 10th October). The increase in scyphistoma coverage mainly resulted from an intense production of buds between February and April during the spring rise in water temperature (peak of 12,800 buds m−2 on 21st April), but scyphistoma coverage appeared to be negatively influenced by the interaction of high summer temperatures and salinities. Strobilation was observed from November to April. It peaked on 17th November, with 33.1% of the scyphistomae strobilating and an average production of 19,100 strobila disks m−2. However, the low scyphistoma coverage at this time of the year (< 2%) likely limited the intensity of ephyrae liberation and the subsequent medusae bloom. The final population size of A. coerulea thus results from a complex interaction of abiotic and biotic factors. Our results bring into question how the different populations of Aurelia spp. will respond to the predicted global warming scenarios.

Blooms and strandings of Chrysaora plocamia are reported to occur along both Atlantic and Pacifi c South American coasts. First described in Peruvian waters by Lesson (1830) almost two centuries ago as Cyanea plocamia , there is surprisingly little ecological information about this conspicuous animal. This chapter reviews current knowledge about C. plocamia biology and ecology, its relationship with pelagic fi sheries and climate and the problems blooms cause in the Humboldt Current and Patagonian shelf ecosystems. Chrysaora plocamia has important ecological roles, including trophic and symbiotic interactions with fi sh and sea turtles. Population variability has a clear relationship with climate where phases of high C. plocamia biomass were associated with El Niño events occurring during warm "El Viejo" regimes. Interestingly, their estimated biomass occasionally approached those of sardines or anchovies. This large jellyfi sh negatively affects human industries in the region when abundant, including fi sheries, aquaculture, desalination plants and tourism. Understanding relationships between jellyfi sh blooms and environmental drivers (e.g. ENSO, regime shifts) should allow forecasting of the jellyfi sh abundance and potential vulnerabilities such that resource managers and industrial fi sheries owners may prepare for costly outbreaks.