The fresh weight, dry weight, and C and N content of the eggs, egg shells and neonate larvae of several satyrines were measured. This was done in order to assess the specificity of the composition of the egg and larvae, the phylogenetic or ecological nature of the variation and the existence of structural constraints on the composition of the offspring. All the traits investigated were found to be highly species-specific. The nature of the variation was not primarily phylogenetic, suggesting that the composition of the offspring has an ecological meaning. However, only a slight association was detected between three life history traits or habitat features and the compositions of the eggs or larvae, namely: female egg dropping was associated with a high C content of the eggs, xerophily with a high C : N ratio, and a high content of N in the larvae with egg diapause. The evidence for intra-specific allometry between the traits investigated and egg weight varied among the species, suggesting that the slope of such relationship may be a specific feature. There was a close to isometric relationship between C and N contents in every species. Therefore simple C : N ratios are independent of egg size, hence they can be used directly in comparative studies. Across species analyses indicated that small offspring contained a proportionally low amount of carbon and had a high dry matter content, suggesting that selection for small eggs was accompanied by selection for an enhanced proportion of nitrogen per egg. Finally, the species with large adult females invested comparatively more nitrogen per egg, which indicates a potential, constraint-based advantage of large adult size.
Although most monitoring protocols characterize fish assemblages based on one sampling occasion per year per site, it is largely unknown how well such snapshot samples characterize fish assemblages at the site and the stream levels. To address these issues, we conducted monthly samplings from March to November in 2009 in two wadeable lowland streams in the catchment area of Lake Balaton, Hungary. Five and seven sites were investigated in the two streams by electric fishing 150 m long sections. For a given sampling site, mean estimated species composition of a single survey showed on average 41 % and 35 % Jaccard index based similarity to the pooled annual samples of the site, and 90 % species representation could be reached using 5.2 and 6.4 sampling occasions on average. The representativeness of relative abundance data also varied considerably in time, showing on average 51 % and 67 % Bray-Curtis index based similarity to the pooled annual samples of the site, and reached 90 % similarity by taking 4.2 and 5.4 surveys on average per year per site. Stream level simulations of sample representativeness showed that a single survey reached on average 62.3 % and 66 % Jaccard similarity and 75.7 % and 74.8 % Bray-Curtis similarity to the whole year dataset. At the stream level, 90 % representativeness of both species composition data and relative abundance data was reached by pooling four surveys for both streams. These results indicate considerable within year variability in lowland stream fish assemblages, which should not be forgotten when evaluating monitoring data, which are based on a single survey per year.