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The distribution, abundance and size structure of a penaeid with tropical affinities (Metapenaeus dalli) was investigated in a temperate, microtidal estuary in south-western Australia. Sampling was conducted every lunar month for two years at 20 sites across five regions (nine subregions) in nearshore waters by hand trawl, and at 16 sites across four regions (eight subregions) in offshore waters by otter trawl. Densities of M. dalli changed markedly seasonally, with greatest values recorded in nearshore waters from October to February, and in offshore waters from March to July. These densities also varied spatially, with the highest recorded in the Lower Canning, Middle Swan, and Upper Melville Water regions. Spearman's rank correlation showed a positive relationship between the density of M. dalli in nearshore waters and surface water temperature in all nine subregions, whilst densities of M. dalli in offshore waters were negatively correlated with bottom water temperature in most of the estuary; these correlations reflect the movement of adult prawns into shallow waters for breeding in summer, as well as the subsequent recruitment and movement back into deeper waters over the winter months. Mean carapace lengths remained relatively unchanged over the late autumn and winter months (May to August), before rapidly increasing with temperature in late spring. The spatial and temporal distribution of M. dalli differed significantly from those of other crustaceans in the estuary, particularly the penaeid Penaeus Merlicertus latisulcatus, which was concentrated mainly in the Lower and Upper Melville Water regions. The distribution of M. dalli was statistically indistinct from that of the apogonid Ostorhinchus rueppellii, which predates heavily on postlarval M. dalli, and very similar to those of two scyphozoans, Aurelia aurita and Phyllorhiza punctata, that likely predate on larval M. dalli. These findings highlight the partitioning of species within the estuary and the significance of site selection for maximising the post-release survival of hatchery-reared M. dalli produced by aquaculture-based enhancement programs.

Since 2008 AquaBioSolutions, the first privately owned jellyfish breeding center, not related to a zoo or a public aquarium, was founded in the Netherlands. With his more than 30 years experience in sea water quality management and work in the Artis Zoo Aquarium in Amsterdam, Piet Sondervan started to breed jellyfish for commercial purpose. The goal was to provide jellyfish to public aquariums and zoos, which do not have the possibility to breed jellyfish by themselves. This article deals with AquaBioSolutions’ experiences of the first five years and with the perspective of the company for the future.

The popularity of jellyfish in Europe at the end of the 19th century influenced the European Art Nouveau period and jellyfish decoration elements can be found at several buildings. But at that time it was still impossible to keep jellyfish for a longer time alive in an aquarium. Methods for the husbandry of jellyfish were developed only in the second half of the 20th century. During the last 20 years the exhibition of jellyfish became more and more popular and is today a standard for all larger aquariums. The development of husbandry is documented on the basis of the husbandry methods for jellyfish in the Berlin Aquarium, which has today one of the leading jellyfish exhibitions in the world.

The aim of the present study was to risk screen 45 jellyfish species (30 hydromedusae, 14 scyphomedusae, one cubomedusa) for their potential invasiveness in the Mediterranean Sea to aid managers in making informed decisions on targeting appropriate species for management. Using the Aquatic Species Invasiveness Screening Kit (AS-ISK), calibrated basic and climate-change threshold assessment scores of 6.5 and 12.5, respectively, were identified for distinguishing reliably between species that pose 'low-to-medium' and 'high' risk of becoming invasive in the risk assessment area. Using these thresholds, 16 species were classified as high risk, 23 as medium risk and six as low risk under current climate conditions. Whereas, under future climate conditions, 13, 30 and two species, respectively, were classified as high, medium and low risk, respectively. Upside-down jellyfish Cassiopea andromeda, Australian spotted jellyfish Phyllorhiza punctata, sea nettle Chrysaora quinquecirrha and Rhopilema nomadica were the highest-scoring species, with the maximum increase in risk score under predicted climate change conditions being achieved by C. andromeda.

The rhizostome jellyfishes, Catostylus mosaicus and Phyllorhiza punctata abound in estuaries in New South Wales, Australia. P. punctata contains symbiotic zooxanthellae but C. mosaicus contains few or no zooxanthellae. Our experiment measured the rates at which NH 3 , PO 4 and NO x were taken up or excreted by each species and in two controls: a “water only” control and a “mucus” control. Rates of uptake or excretion were measured as changes in the nutrient concentration of the water in the containers housing the animals over periods of 6 h. Experiments were repeated twice during the day and twice at night, under both ambient and enriched nutrient conditions. Under ambient nutrient conditions, the flux of NH 3 in the P. punctata treatment did not differ from the controls but under enriched conditions P. punctata excreted NH 3 during the night (49 μg kg −1 WW (wet weight) h −1 ) and took up NH 3 during the day (123 μg kg −1 WW h −1 ). In contrast, C. mosaicus excreted NH 3 at a rate of 1555 μg kg −1 WW h −1 during the day and 1004 μg kg −1 WW h −1 during the night under both enriched and ambient nutrient conditions. P. punctata neither took up nor excreted PO 4 but C. mosaicus excreted PO 4 at a faster rate during the day than night (173 μg kg −1 WW h −1 cf. 104 μg kg −1 WW h −1 ). Both C. mosaicus and P. punctata excreted NO x and, although the rate of excretion for P. punctata varied between the two experiments conducted during the day, the rate of excretion was consistently greater than for C. mosaicus (52 and 80 μg kg −1 WW h −1 cf. 26 μg kg −1 WW h −1) . Tubs containing P. punctata had a much greater concentration of dissolved oxygen at the end of the experiments conducted during the day (152% saturation) than night (60% saturation) but tubs containing C. mosaicus had a greater dissolved oxygen concentration during the night (47% saturation) than day (39%). Overall, C. mosaicus appears to recycle more inorganic nutrients to estuaries than P. punctata . Calculations of the importance of inorganic nitrogen excreted by this species during times of peak biomass in Lake Illawarra suggest that it can meet about 8% of the phytoplankton primary production requirements of N and that its inorganic N excretion rate is about 11% of measured inorganic ammonia fluxes from sediments in that system. Since the biomass of C. mosaicus often exceeds several thousand tonnes, the contribution of inorganic nutrients by this species is substantial.

This study examined the influence of predation by a population of the scyphomedusa Phyllorhiza punctata von Lendelfeld on temporal and spatial variations in abundance of planktonic copepods in Laguna Joyuda. Experimentally determined clearance rates were independent of prey densities (Type I response) and increased linearly with medusa bell diameter, within the range of prey concentrations and size of individuals tested. Variations in size of medusae (range 3–24 cm bell diameter) explained 81% of the variability in clearance rates on copepod nauplii, 63% on post-naupliar copepods, and 83% on a combined copepod assemblage from Laguna Joyuda. Population clearance rates were highest during July and August, representing a filtering capacity of ≈22 and 35%·day −1 of the lagoon's volume. Relatively large medusae (7–21 cm) were the principal predatory size group during July and August. Clearance rates of P. punctata remained constant for prey densities above 200 prey·l −1 on the mixed copepod assemblage. These prey densities are higher than average (even patch) densities in Laguna Joyuda, which imply that ingestion rates were constantly varying in the field. Variations in estimated field ingestion rates on average and patch prey densities explained 79 and 84%, respectively, of the variability in observed growth rates of Phyllorhiza in Laguna Joyuda. The estimated (potential) field ingestion rates represent mean daily ratios [as % medusa (ash-free dry weight (AFDW)] of 3.1% (9.1% max.) on mean prey densities, and 6.4% (16.3% max.) on patch prey densities. These daily rations on planktonic copepods appear low in relation to the observed growth rates of Phyllorhiza in Laguna Joyuda, suggesting that algal endosymbionts and/or other nutritional sources play an important role in its bioenergetics.