Effekte nicht-tödlicher Strandkrabben (Carcinus maenas) auf das Paarungsverhalten der Gemeinen Strandschnecke Littorina littorea.

Despite considerable progress in the study of predator-prey interactions, our understanding of the role of non-lethal effects in this relationship remains limited. Except of consumption the presence of a predator often causes a behavioural shift in the prey species, called risk effects. They occur immediately by appearance of the predator and can effect the entire prey population. This is the first study dealing with changes in reproduction as a behavioural response to predation in the common periwinkle Littorina littorea. It is a factorial laboratory experiment to analyse the risk effect of the common shore crab Carcinus maenas on the mating success of L. littorea quantified at the number of eggs per female and unit of time. Exposure to water-borne chemical cues from feeding predatory crab caused the snail to decrease their number of eggs significantly about 40%, whereas another crab species (Cancer pagurus), damaged conspecific as well as starving crabs had no effect on the mating success. Furthermore, there was a tendency for decreased feeding activity of the snails when C. maenas were present. These results demonstrate that L. littorea is able to detect risk cues from the widespread predator C. maenas and response with a risk effect in terms of a reduced number of eggs. This shift may be either a direct behavioural answer to increase the chance of survival because the act of copulation enhance visual, tactile and chemical conspicuousness to predators, or a result of diversion of energy or time from reproductive tasks into anti-predator behaviour as escape or refuge seeking. However, it illustrates the potential for chemical cues as a non-lethal interaction between predator and prey, released by actively foraging C.maenas, to have profound effects on gastropod reproduction and by implication on the abundance of the next snail generation

Aquatische Optische Technologien in Deutschland

Optische Technologien und Verfahren sind sowohl in der limnischen als auch marinen Forschung Deutschlands über alle Bereiche und Skalen etabliert und entwickeln sich rasant weiter. Die Arbeitsgruppe „Aquatische Optische Technologien“ (AOT) will Forschern und Anwendern eine Plattform bieten, die Wissenstransfer fördert, der nationalen Entwicklergemeinschaft ein synergistisches Umfeld eröffnet und die internationale Sichtbarkeit der deutschen Aktivitäten in diesem Forschungsfeld erhöht. Diese Zusammenfassung dokumentiert erstmalig die AOT-Verfahren und -Technologien, die von nationalen Forschungsinstitutionen eingesetzt werden. Wir erwarten, dass die Dokumentation einen Trend in Richtung institutsübergreifender Harmonisierung initiiert. Dies wird die Etablierung offener Standards, eine Verbesserung im Zugang zu Dokumentationen und gegenseitige technischer Hilfestellung bei (System-) Integrationen ermöglichen. Effizienz und Leistungsfähigkeit der AOT-Entwicklung und Anwendung auf nationaler Ebene werden von diesen Bestrebungen profitieren. Weitere Arbeitsgruppen und Entwickler werden ausdrücklich ermutigt, Kontakt aufzunehmen, um in einer späteren Auflage berücksichtigt zu werden

Current and future trends in marine image annotation software

Nuno Gomes-Pereira J, Auger V, Beisiegel K, et al. Current and future trends in marine image annotation software. Progress in Oceanography. 2016;149:106-129.Abstract Given the need to describe, analyze and index large quantities of marine imagery data for exploration and monitoring activities, a range of specialized image annotation tools have been developed worldwide. Image annotation - the process of transposing objects or events represented in a video or still image to the semantic level, may involve human interactions and computer-assisted solutions. Marine image annotation software (MIAS) have enabled over 500 publications to date. We review the functioning, application trends and developments, by comparing general and advanced features of 23 different tools utilized in underwater image analysis. \{MIAS\} requiring human input are basically a graphical user interface, with a video player or image browser that recognizes a specific time code or image code, allowing to log events in a time-stamped (and/or geo-referenced) manner. \{MIAS\} differ from similar software by the capability of integrating data associated to video collection, the most simple being the position coordinates of the video recording platform. \{MIAS\} have three main characteristics: annotating events in real time, in posteriorly to annotation and interact with a database. These range from simple annotation interfaces, to full onboard data management systems, with a variety of toolboxes. Advanced packages allow to input and display of data from multiple sensors or multiple annotators via intranet or internet. Posterior human-mediated annotation often include tools for data display and image analysis, e.g. length, area, image segmentation, point count; and in a few cases the possibility of browsing and editing previous dive logs or to analyze annotation data. The interaction with a database allows the automatic integration of annotations from different surveys, repeated annotation and collaborative annotation of shared datasets, browsing and querying of data. Progress in the field of automated annotation is mostly in post processing, for stable platforms or still images. Integration into available \{MIAS\} is currently limited to semi-automated processes of pixel recognition through computer-vision modules that compile expert-based knowledge. Important topics aiding the choice of a specific software are outlined, the ideal software is discussed and future trends are presented