Breeding and growth of the burrowing prawn Calhanassa kraussi stebbing (Crustacea: Decapoda: Thalassinidea)

1. C. kraussi in the Swartkops river estuary in South Africa has a major breeding period in winter-spring (May-July/August) and a minor breeding period in summer (November-January).2. A maximum of 43 per cent of ovigerous mature females was recorded. Females in the 8 and 9 mm carapace-size classes make the major contribution to the breeding effort.3. Recruitment is very marked with 60-80 per cent of the population consisting of juveniles at times.4. Both sexes live for about two years. Females hatching in winter-spring may breed first in summer at an age of about 16-18 months and then again in the following winter at an age of about two years. Females hatching in summer breed first in winter at an age of about 18 months and some in the following summer at an age of about two years.5. Breeding and growth in C. kraussi is compared with that in other known callianassids, and discussed in relation to estuarine eco-systems and conservation measures

Biology of Hymenosoma orbiculare Desm in Lake Sibaya

Hymenosoma orbiculare, (Crustacea: Brachyura: Hymenosomatidae) a crab common in estuaries in south- and south east Africa occurs in freshwater in Lake Sibaya at depths down to 40 m. This is the only known freshwater record of this species. The population density in the lake is fairly uniform declining in shallow and very deep water with an a11erage- of 2,5 m-2 (134 Jm-2). The proportion of females in the population increases with depth. Females carry fewer eggs than estuarine populations and breeding appears to occur throughout the year. Both zoeae and adults differ morphologically from estuarine populations. These differences in breeding, biology and morphology raise the possibility that the Lake Sibaya population is specifically distinct from estuarine populations and this is discussed in relation to other instances of hymenosomatid invasion of freshwater habitats.Hymenosoma orbiculare, (Crustacea: Brachyura: Hymenosomatidae) 'n krap wat algemeen voorkom in riviermondings in suid en suidoos Afrika, word ook aangetref in die varswater van die Sibayameer tot op 'n diepte van 40 m. Dit is die enigste bekende geval van hierdie spesie se voorkoms in varswater. Die populasiedigtheid is redelik eenvormig en neem af vanaf vlak tot baie diep water met 'n gemiddeld van 2,5 m-2 (134 Jm -2). Die verhouding van wyfies tot mannetjies neem toe met toename in diepte. Wyfies dra minder eiers as die in riviermondings en voortplanting vind blykbaar dwarsdeur die jaar plaas. Seide die zoeae en volwassenes verskil morfologies van die in riviermondings. Hierdie verskille in teling, biologie en morfologie dui op 'n moontlike spesieverskil tussen die bevolking in die Sibayameer en die in riviermondings. Hierdie aspekte word bespreek in die lig van ander gevalle van toetreding tot varswaterhabitatte onder die Hymenosomatidae

Penaeid prawns in the St Lucia Lake System: Post-larval recruitment and the bait fishery

Recruitment of post-larval penaeid prawns and the bait prawn fishery in the St Lucia Lake System were monitored for two years before and one year after Cyclone Domoina. Post-larval Penaeus indicus Milne-Edwards, P. monodon Fabricius, P. japonicus Bate, P. semisulcatus de Haan and Metapenaeus monoceros (Fabricius) were found. Recruitment was dominated by P. japonicus but P. indicus was the major species taken in the bait fishery. M. monocero scatches in the fishery increased during the low salinity conditions following the cyclone. Differences in species ratios between the post-larvae and the bait fishery, factors affecting recruitment, the size of the bait catch and the relationship between recruitment and catch are discussed

Macroinvertebrate communities associated with intertidal and subtidal beds of Pyura stolonifera (Heller) (Tunicata: Ascidiacea) on the Natal coast

The solitary ascidian Pyura stolonifera occurs in dense beds on the low intertidal and shallow subtidal rocky shore along the entire South African coastline. The organism is used as bait by fishermen and is also heavily exploited for food in certain areas. The crevices and interstices between individuals in dense beds of P. stoloniferaprovide a safe and stable habitat for a wide variety of benthic macroinvertebrates. Sixty-four and 61 taxa representing 10 phyla, of associated organisms were recorded respectively in an intertidal and a subtidal P. stolonifera bed. Forty-two taxa were common to both, but communities of macroinvertebrates associated with intertidal and subtidal P. stolonifera beds were different. Numerically, polychaetes (30%) were the dominant group intertidally, and crustaceans (40%) subtidally. Porifera formed 71% of the biomass of associated intertidal organisms, while subtidal biomass was dominated by the bivalves Striostrea margaritacea and Perna perna (87%). Mean dry biomass of macroinvertebrates was 366 g.m −2 ( SD = 196) intertidally and 670 g.m −2 (SD = 119) subtidally. These values are between four and eight times higher than those recorded on the southern Cape coast. Recolonization of cleared areas is slow, so considerable secondary production is lost when harvesting practices result in bare patches in P. stolonifera beds

Book Reviews

Book Review 1Book Title: Sharks and Rays of AustraliaBook Authors: P.R. Last & J.D. StevensPrinted and distributed by CSIRO, P.O. Box 89 East Melbourne. 3002 Australia, 1994. 612 pages and 84 colour plates.Book Review 2Book Title: The Ecology of Mangrove and Related Ecosystems.  Proceedings of the International Symposium held at Mombasa, Kenya 24-30 September 1990Book Authors: Edited by Victor Jaccarini & Els MartensKluwer Academic Publishers, Dordrecht 1993. 272 pages. Hardbound. ISBN 0-7923-2049-2.Book Review 3Book Title: Rotifer Symposium VI. Proceedings of the Sixth International Rotifer Symposium, held in Banyoles, Spain, June 3-8, 1991Book Authors: Edited by J.J. Gilbert, E. Lubzens & M.R. MiracleReprinted from Hydrobiologia, vols 255-256, as Developments in Hydrobiology 83Kluwer Academic Publishers, Dordrecht /Boston /London. 572 pagesBook Review 4Book Title: Identification Guide to the Ant Genera of the WorldBook Author: Barry BoltonHarvard University Press, 1994. 224 pages, 522 SEM photographs. ISBN 0-674-44280-

Star clusters near and far; tracing star formation across cosmic time

© 2020 Springer-Verlag. The final publication is available at Springer via https://doi.org/10.1007/s11214-020-00690-x.Star clusters are fundamental units of stellar feedback and unique tracers of their host galactic properties. In this review, we will first focus on their constituents, i.e.\ detailed insight into their stellar populations and their surrounding ionised, warm, neutral, and molecular gas. We, then, move beyond the Local Group to review star cluster populations at various evolutionary stages, and in diverse galactic environmental conditions accessible in the local Universe. At high redshift, where conditions for cluster formation and evolution are more extreme, we are only able to observe the integrated light of a handful of objects that we believe will become globular clusters. We therefore discuss how numerical and analytical methods, informed by the observed properties of cluster populations in the local Universe, are used to develop sophisticated simulations potentially capable of disentangling the genetic map of galaxy formation and assembly that is carried by globular cluster populations.Peer reviewedFinal Accepted Versio

The psychological science accelerator’s COVID-19 rapid-response dataset

In response to the COVID-19 pandemic, the Psychological Science Accelerator coordinated three large-scale psychological studies to examine the effects of loss-gain framing, cognitive reappraisals, and autonomy framing manipulations on behavioral intentions and affective measures. The data collected (April to October 2020) included specific measures for each experimental study, a general questionnaire examining health prevention behaviors and COVID-19 experience, geographical and cultural context characterization, and demographic information for each participant. Each participant started the study with the same general questions and then was randomized to complete either one longer experiment or two shorter experiments. Data were provided by 73,223 participants with varying completion rates. Participants completed the survey from 111 geopolitical regions in 44 unique languages/dialects. The anonymized dataset described here is provided in both raw and processed formats to facilitate re-use and further analyses. The dataset offers secondary analytic opportunities to explore coping, framing, and self-determination across a diverse, global sample obtained at the onset of the COVID-19 pandemic, which can be merged with other time-sampled or geographic data

Velocity-space sensitivity of the time-of-flight neutron spectrometer at JET

The velocity-space sensitivities of fast-ion diagnostics are often described by so-called weight functions. Recently, we formulated weight functions showing the velocity-space sensitivity of the often dominant beam-target part of neutron energy spectra. These weight functions for neutron emission spectrometry (NES) are independent of the particular NES diagnostic. Here we apply these NES weight functions to the time-of-flight spectrometer TOFOR at JET. By taking the instrumental response function of TOFOR into account, we calculate time-of-flight NES weight functions that enable us to directly determine the velocity-space sensitivity of a given part of a measured time-of-flight spectrum from TOFOR