Rotifers in the Schelde estuary (Belgium): a test of taxonomic relevance

To investigate the reaction of the zooplankton community to improving water quality in the Schelde estuary, we studied the relationship between rotifer species distribution and environmental factors, and the feasibility of using a coarser level of taxonomic resolution. Fifty-two taxa, belonging to 26 genera, were identified, including 22 taxa new for the Schelde. Brachionus calyciflorus, Keratella cochlearis and B. angularis were the most abundant species. The highest diversity and abundances were observed in the freshwater reach. Redundancy analyses (RDA) showed that the main environmental factors explaining rotifer distribution were chlorinity and seasonal factors (discharge levels, cyclopoid abundance). Analysis carried out with data at the species and the genus level gave similar ordination plots, but the positioning of a genus relative to environmental factors did not always adequately represent the associations between the various species within the genus and environmental factors. Similar patterns in space and time were observed using taxonomic richness and diversity indices for analyses at species or genus level. Thus, in the context of the restoration of the Schelde estuary, the identification of rotifer species is very informative, but not essential for detecting important ecological associations

Environmental cues and constraints affecting the seasonality of dominant calanoid copepods in brackish, coastal waters: a case study of Acartia, Temora and Eurytemora species in the south-west Baltic

Information on physiological rates and tolerances helps one gain a cause-and-effect understanding of the role that some environmental (bottom–up) factors play in regulating the seasonality and productivity of key species. We combined the results of laboratory experiments on reproductive success and field time series data on adult abundance to explore factors controlling the seasonality of Acartia spp., Eurytemora affinis and Temora longicornis, key copepods of brackish, coastal and temperate environments. Patterns in laboratory and field data were discussed using a metabolic framework that included the effects of ‘controlling’, ‘masking’ and ‘directive’ environmental factors. Over a 5-year period, changes in adult abundance within two south-west Baltic field sites (Kiel Fjord Pier, 54°19′89N, 10°09′06E, 12–21 psu, and North/Baltic Sea Canal NOK, 54°20′45N, 9°57′02E, 4–10 psu) were evaluated with respect to changes in temperature, salinity, day length and chlorophyll a concentration. Acartia spp. dominated the copepod assemblage at both sites (up to 16,764 and 21,771 females m−3 at NOK and Pier) and was 4 to 10 times more abundant than E. affinis (to 2,939 m−3 at NOK) and T. longicornis (to 1,959 m−3 at Pier), respectively. Species-specific salinity tolerance explains differences in adult abundance between sampling sites whereas phenological differences among species are best explained by the influence of species-specific thermal windows and prey requirements supporting survival and egg production. Multiple intrinsic and extrinsic (environmental) factors influence the production of different egg types (normal and resting), regulate life-history strategies and influence match–mismatch dynamics

Advertising, earnings prediction and market value: An analysis of persistent UK advertisers

YesThis paper examines whether major media advertising expenditures help in predicting future earnings. We consider the role of media advertising in firms’ marketing efforts and posit that persistent advertisers are more likely to benefit from advertising activities in creating long‐lived intangible assets. Employing a sample of persistent UK advertisers over the period 1997–2013, we find that advertising expenditures are significantly positively associated with firms’ future earnings and market value. We also report size and sector‐based differences in the association between advertising and firms’ future earnings. Our additional analysis provides support for the arguments that despite the recent rise in digital advertising budgets, traditional advertising media are still effective in positively influencing firms’ performance. Overall, the results of this study are consistent with the view that advertising expenditures produce intangible assets, at least for firms in certain sectors. These findings have implications for marketers in providing evidence of the value generated by firms’ advertising budgets, for investors in validating the relevance of advertising information in influencing future earnings, and for accounting regulators in relation to the provision of useful insights for any future deliberations on financial reporting policies for advertising expenditures

Effect of incubation time and concentration of animals in grazing experiments using a narrow size range of particles

Three concentrations of A. tonsa adults were allowed to feed on a narrow size range suspension of particles. Sampling was done at 4-hour intervals during 24 hours. It is shown that both animal concentration and incubation time considerably influence the obtained ingestion rates and filtering-spectra. These results are discussed in relation to different calculation methods and models

Zooplankton grazing pressure in the Oosterschelde (the Netherlands)

Grazing activity by the dominant zooplankton species in the Oosterschelde (SW Netherlands) was studied as part of an ecological survey accompanying the construction of a storm-surge barrier at the mouth of this tidal inlet. At station WEST, situated at the mouth, potential grazing pressure by the zooplankton amounted to 6% d-1 of the phytoplankton standing stock and 18% of the primary production. At station EAST, in the inland part, 16% of the phytoplankton standing stock and 11% of the primary production was potentially consumed daily. Because the dominant zooplankton species in the inland part (Acartia spp. and cirriped nauplii) tended to feed more on small particles than the dominant species in the seaward part (Temora longicornis and Centropages hamatus), the potential grazing pressure on small phytoplankton (<20 µm Spherical Equivalent Diameter) was 3 times higher at station EAST than at station WEST. Ecological consequences of this difference are discussed in relation to developments to be expected in the post-barrier situation