Influences of temperature and salinity on asexual reproduction and development of scyphozoan jellyfish from the British Isles

Jellyfish (Phylum Cnidaria, Class Scyphozoa) play important roles in pelagic ecosystems as predators and prey. Seasonally they form blooms facilitating reproductive success, but that are at times problematic for human enterprise. Medusa abundance has been correlated with environmental variables in several instances. However, the direct mechanisms for changes in medusa abundance are unclear. As global sea surface temperatures continue to change there is increasing concern that warming may enhance conditions favourable for the generation of jellyfish medusae. It is important to understand the ways in which temperature affects all life history stages of jellyfish if we are to begin to understand factors associated with jellyfish bloom formations, but how temperature and salinity affects life history stages of scyphozoan jellyfish from British waters remains largely unknown. In Chapter 1 I provide a general introduction to some key issues important to the formation of jellyfish blooms. In Chapter 2 I present results for experiments testing the effects of temperature on settlement and metamorphosis of planulae larvae of Cyanea capillata, Cyanea lamarckii, Chyrsaora hysoscella, and Aurelia aurita. Chapter 3 reports on the effects of temperature and salinity on survival, and asexual reproduction of scyphistomae of the same species. Chapter 4 reports on the effects of temperature and salinity on growth of newly released ephyrae of each of the above mentioned species, as well as the effects of starvation on survivorship on ephyrae of A. aurita originating from two distinct populations of scyphistomae. In Chapter 5 I provide a brief summary of significant findings for each life history stage, their theoretical implications when taken together, and next steps for future research. I also offer recommendations for ecosystem managers with an eye toward affecting the numbers of near-shore jellyfish medusae generated each season in the waters surrounding the British Isles

Effects of temperature and salinity on four species of northeastern Atlantic scyphistomae (Cnidaria Scyphozoa)

This work was funded by the MASTS pooling initiative (Marine Alliance for Science and Technology for Scotland), and we gratefully acknowledge that support. MASTS is funded by the Scottish Funding Council (grant reference HR09011) and contributing institutions. C.L.W. is also grateful to the US/UK Fulbright Commission and the University of St Andrews for their financial support.Laboratory incubation experiments were conducted to examine the effects of different temperatures (4, 9, 14, 19, 23°C) and salinities (21, 27, 34) on survival and asexual reproduction of scyphistomae of Cyanea capillata, C. lamarckii, Chrysaora hysoscella, and Aurelia aurita in order to better understand how climate variability may affect the timing and magnitude of jellyfish blooms. Significant mortality was observed only for C. capillata and Ch. hysoscella at the highest and lowest temperatures, respectively, but temperature and salinity significantly affected the asexual reproductive output for all species. As temperature increased, production rates of podocysts increased and, if produced, progeny scyphistomae by side budding also increased. However, strobilation rates, and therefore the mean number of ephyrae produced, decreased when scyphistomae were exposed to elevated temperatures. These results provide a mechanistic explanation for why ephyrae of these species tend to be produced during colder periods of the year whilst summer and early autumn are probably important periods for increasing the numbers of scyphistomae in natural populations.PostprintPeer reviewe

The (111) Surface of NaAu2: Structure, Composition, and Stability

The (111) surface of single-crystal NaAu2 is a model for catalytically active, powdered NaAu2. We prepare and characterize this surface with a broad suite of techniques. Preparation in ultrahigh vacuum consists of the traditional approach of ion bombardment (to remove impurities) and thermal annealing (to restore surface order). Both of these steps, however, cause loss of sodium (Na), and repeated treatments eventually trigger conversion of the surface and near-surface regions to crystalline gold. The bulk has a limited ability to repopulate the surface Na. Under conditions where Na depletion is minimized, electron diffraction patterns are consistent with the bulkterminated structure, and scanning tunneling microscopy reveals mesa-like features with lateral dimensions of a few tens of nanometers. The tops of the mesas do not possess fine structure characteristic of a periodic lattice, suggesting that the surface layer is disordered under the conditions of these experiments

Life Cycle of Chrysaora fuscescens (Cnidaria: Scyphozoa) and a Key to Sympatric Ephyrae.

v. ill. 23 cm.QuarterlyThe life cycle of the Northeast Pacific sea nettle, Chrysaora fuscescens Brandt, 1835, is described from gametes to the juvenile medusa stage. In vitro techniques were used to fertilize eggs from field-collected medusae. Ciliated planula larvae swam, settled, and metamorphosed into scyphistomae. Scyphistomae reproduced asexually through podocysts and produced ephyrae by undergoing strobilation. The benthic life history stages of C. fuscescens are compared with benthic life stages of two sympatric species, and a key to sympatric scyphomedusa ephyrae is included. All observations were based on specimens maintained at the Monterey Bay Aquarium jelly laboratory, Monterey, California

The hydroid and medusa of Amphinema rollinsi (Cnidaria: Hydrozoa), a new species of pandeid from the Monterey Bay Submarine Canyon, USA

Widmer, Chad L. (2007): The hydroid and medusa of Amphinema rollinsi (Cnidaria: Hydrozoa), a new species of pandeid from the Monterey Bay Submarine Canyon, USA. Zootaxa 1595: 53-59, DOI: 10.5281/zenodo.17867

FIGURE 1 in The hydroid and medusa of Amphinema rollinsi (Cnidaria: Hydrozoa), a new species of pandeid from the Monterey Bay Submarine Canyon, USA

FIGURE 1. Hydroid of Amphinema rollinsi, sp. n.: A. Upright hydrocaulus. B. Mature hydranth. C. Medusa bud nearly ready for release. Scale bar A = 5 mm. Scale bars B and C = 500 µm

Jellyfish Life Histories: Role of Polyps in Forming and Maintaining Scyphomedusa Populations

Large population fluctuations of jellyfish occur over a variety of temporal scales, from weekly to seasonal, inter-annual and even decadal, with some regions of the world reported to be experiencing persistent seasonal bloom events. Recent jellyfish research has focussed on understanding the causes and consequences of these population changes, with the vast majority of studies considering the effect of changing environmental variables only on the pelagic medusa. But many of the bloom-forming species are members of the Scyphozoa with complex metagenic life cycles consisting of a sexually reproducing pelagic medusa and asexually reproducing benthic polyp. Recruitment success during the juvenile (planula, polyp and ephyrae) stages of the life cycle can have a major effect on the abundance of the adult (medusa) population, but until very recently, little was known about the ecology of the polyp or scyphistoma phase of the scyphozoan life cycle. The aim of this review is to synthesise the current state of knowledge of polyp ecology by examining (1) the recruitment and metamorphosis of planulae larvae into polyps, (2) survival and longevity of polyps, (3) expansion of polyp populations via asexual propagation and (4) strobilation and recruitment of ephyrae (juvenile medusae). Where possible, comparisons are made with the life histories of other bentho-pelagic marine invertebrates so that further inferences can be made. Differences between tropical and temperate species are highlighted and related to climate change, and populations of the same species (in particular Aurelia aurita) inhabiting different habitats within its geographic range are compared. The roles that polyps play in ensuring the long-term survival of jellyfish populations as well as in the formation of bloom populations are considered, and recommendations for future research are presented

Characterizations of juvenile stages of some semaeostome Scyphozoa (Cnidaria), with recognition of a new family (Phacellophoridae)

Phacellophora camtschatica has long been assigned to the semaeostome scyphozoan family Ulmaridae. Early stages (scyphistomae, strobilae, ephyrae, postephyrae, and young medusae) of the species were compared with those of several other semaeostomes currently assigned to Ulmaridae, Pelagiidae, and Cyaneidae. Juveniles of P. camtschatica did not strictly conform with characters of those of any of these families, and appeared intermediate between Cyaneidae and Ulmaridae. A new family, Phacellophoridae, is proposed to accommodate P. camtschatica.Alexander von Humboldt FoundationAlexander von Humboldt Foundation (AvH)FAPESP[2003/02433-0]Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)CNPq[481399/2007-0]Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq