1. The aim of this study was to estimate patchiness in biomass and in the internal nutrient status of benthic algae on hard substrata (epilithon) in Lake Erken, Sweden, over different levels of distance, depth and time. Knowledge of the sources and scale of patchiness should enable more precise estimation of epilithic biomass and nutrient status for the entire lake. We focused on the horizontal scale, about which little is known. 2. We sampled epilithon by SCUBA diving and used a hierarchical sampling design with different horizontal scales (cm, dm, 10 m, km) which were nested in two temporal scales (within and between seasons). We also compared two successive years and three sampling depths (0, 1 and 4 m). Biomass was measured as particulate carbon and chlorophyll a (Chl a) and internal nutrient status as carbon : nitrogen : phosphorus (C : N : P) ratios and as specific alkaline phosphatase activity (APA). 3. Horizontal variation accounted for 60–80 and 7–70% of the total variation in biomass and in nutrient status, respectively, at all depths and during both years. Both small and large scales accounted for significant variation. We also found variation with time and depth. Biomass increased in autumn after a summer minimum, and the within‐season variation was very high. The lowest biomass was found at 0 m depth. Both N and P limitation occurred, being higher in 1996 than in 1997 and decreased with depth. 4. As a consequence, any sampling design must address variation with distance, depth and time when estimating biomass or nutrient limitation of benthic algae for an entire lake. Based on this analysis, we calculated an optimal sampling design for detecting change in the epilithic biomass of Lake Erken between different sampling days. It is important to repeat the sampling as often as possible, but also the large scales (10 m and km) and the dm scale should be replicated. Using our calculations as an example, and after a pilot study, an optimal sampling design can be computed for various objectives and for any lake. 5. Short‐term impact of the wind, light and nutrient limitation, and grazing, might be important in regulating the biomass and nutrient status of epilithic algae in Lake Erken. Patchiness in the nutrient status of algae was not coupled to the patchiness of biomass, indicating that internal nutrients and biomass were regulated by different factors.

The psychomyiid caddis fly Tinodes waeneri (L.) mated on a shrub near the shore-line (and the littoral emergence site) and on adjacent flowers. Both males and females were shown to ingest nectar, from different species of flowers having open nectaries (mostly of the family Apiaceae). Male fat content was negatively correlated with age (wing wear), indicating that ingested nectar did not restore lipids. Therefore, we presume that nectar was mainly used for mechanical activities (e. g. flying, walking, mating). A male lost about 7% of his original carbon and nitrogen during copulation, suggesting that they had the potential to copulate often. The sex ratio differed between the shrub and flower habitats, and females on flowers were also older and had more frequently laid eggs. Thus, females seemed to mate as virgins on the shrub, deposited their first egg batch, returned to the shore, ingested nectar from the flowers and copulated again. Males on flowers encountered proportionally more females, but those females contained on average only 3% of the number of eggs compared with females on the shrub.

Business processes have tremendously changed the way large companies conduct their business: The integration of information systems into the workflows of their employees ensures a high service level and thus high customer satisfaction. One core aspect of business process engineering are events that steer the workflows and trigger internal processes. Strict requirements on interval-scaled temporal patterns, which are common in time series, are thereby released through the ordinal character of such events. It is this additional degree of freedom that opens unexplored possibilities for visualizing event data. In this paper, we present a flexible and novel system to find significant events, event clusters and event patterns. Each event is represented as a small rectangle, which is colored according to categorical, ordinal or intervalscaled metadata. Depending on the analysis task, different layout functions are used to highlight either the ordinal character of the data or temporal correlations. The system has built-in features for ordering customers or event groups according to the similarity of their event sequences, temporal gap alignment and stacking of co-occurring events. Two characteristically different case studies dealing with business process events and news articles demonstrate the capabilities of our system to explore event data.

An epifluorescence microscope photometer was used to develop a new, in vivo fluorimetric method for analyzing fluorescence intensities of epilithic microalgae grown on clay tiles in the field. This enabled a nondestructive, direct quantification of algal biomass on the substratum surface. Measurements of a chlorophyll a standard in ethanol (90%) with our fluorimetric method (exitation at 546 nm; emission, >590 nm) correlated well with those from conventional spectrofluorimetric and spectrophotometric methods. Biofilms were analyzed with the microscope photometer by measuring the in vivo fluorescence intensity of 70 spots distributed randomly over the tile surface. They were then analyzed by the two in vitro methods after photopigment extraction. Chlorophyll a content and in vivo fluorescence intensity correlated well. The regression curves were linear up to 6 g cm ؊2 but were quadratic or hyperbolic at higher concentrations of up to 28 g cm ؊2. The degree of scatter among individual measurements was higher in biofilms than chlorophyll a standards. This in vivo analysis is well suited to ecological experiments and has the advantage of measuring on an extremely small scale, which enables direct analysis of the microdistribution of epilithic microalgae in live biofilms. We demonstrated this by comparing fluorescence intensities of the grazing tracks of the snail Ancylus fluviatilis with those of ungrazed areas. Our in vivo analysis is also unique in enabling biofilms on artificial substrata to be removed, analyzed, and then returned intact in field or laboratory experiments.

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