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In this thesis, a new approach for the dynamic time domain simulation of highly flexible maritime continua such as moorings, anchor lines, tow lines, tethered vehicles as well as nets for fishing, cages in aquacultures or plankton sampling is presented and evaluated. Here, in contrast to the methods typically applied, the algorithm is neglecting deformations in the longitudinal directions of the investigated continua. In doing so, much larger time step sizes can be achieved, since the high eigenfrequencies introduced from longitudinal vibrations of the systems are thus repressed.

Die Arbeit zeigt, wie tiefgehendes Systemverständnis von Unterwasserfahrzeugen (UUVs), zweckmäßige Bewegungsplanung und umfängliche Reglersynthese ineinander greifen können. Dazu wurde Unsicherheiten (u.a. Zähigkeits- und Trägheitskräfte sowie Fluiddichte) an diversen UUVs detailliert behandelt. Den Kern stellt aber ein entwickelter Algorithmus auf Basis der „Methode der elastischen Bänder“ zur Planung im 3D-Raum dar, mit dessen Hilfe unterschiedliche Aufgaben der UUVs modelliert werden können. Zu deren Realisierung wurde eine Zustandsregelung mit Polbereichsvorgabe beispielhaft vorgeführt., The thesis presents how in-depth system understanding of underwater vehicles (UUVs), proper motion planning and a comprehensive controller synthesis can intertwine. To this end, uncertainties on various UUVs (e.g. viscous and inertial loads as well as fluid density) were dealt with in detail. However, the core is a developed algorithm based on the ‚method of elastic bands’ for planning in a 3D space. It can be used to model the different tasks of UUVs. For their realisation a state control with pole range specification was exemplarily demonstrated.

This paper gives an overview of the work undertaken at the University of Split as a part of national research programme, with aim to evaluate the impact of fish farms on marine ecosystem. Croatian finfish aquaculture has spread rapidly over the past decade. Despite the observed influence of fish farms on marine ecosystem, obligated monitoring is farm-specific and usually requires the assessment of macrobenthos, plankton and chemical parameters of water and sediment. The aim of this study was to evaluate the usage of organisms not included in standard monitoring (meiofauna, wild fish aggregated around the cages) as potential method of assessing impact of fish farms and its structures on the marine environment. Meiofauna organisms are good environmental indicators with a crucial role in nutrient cycling and in energy flow of benthic division. Biodeposition caused by fish farm activities can provoke changes in meiofaunal abundance, community structure and biodiversity. To investigate this, meiofauna samples were collected on two different stations, one situated below the fish farm and the other one in area without fish farm impact. Net-cage fish farms structures are known artificial fish aggregation devices widely recognized for their capacity to attract a great number of wild fish, altering their behaviour and physiology. Wild fish affected by farms could be possible environmental indicators, thus bogue (Boops boops), as one of the most abundant fish species around the farm cages was investigated, using samples caught from populations aggregated around fish farming cages and from area not influenced by the fish farms. Statistically significant difference was observed in meiofauna regarding the sampling location. Also, bogue samples differed in proximate composition and other investigated physical and chemical parameters. All variables were submitted to multivariate analyses in order to evaluate the importance of each studied parameter, thus to separate the variables that describe cage affected changes that could be used in the biological monitoring. The principal component analyses showed distinct separation of wild and farm affected samples, placing the sets of data opposite to each other in both meiofauna and bogue analyses. Two main factors (farm impact and depth) had affected the distribution and abundance of meiofauna organisms, but farm impact was found the most significant. Similar was with bogues, catching ground induced most differences between samples. Monitoring of meiobenthos and wild fish populations aggregated around the farms could be used as monitoring requirements of assessing influence of fish farms structures on the marine environment.

The use of robotics finds more and more space among applications in marine environment. Once restricted to military and oil drilling applications, the today's underwater robotics covers more disciplines. It became a cheap, reliable and affordable platform that can be used in various surveys, mapping and other underwater activities by both research communities as well as various types of industry. It finds applications in marine biology, archeology and ecology. The general aim, purpose and the reason for using the underwater robots is gathering better knowledge about marine environment and consequently perform better management of underwater resources. This paper presents the applications of underwater technology in fishing and fish farming. Along these lines several potential applications, addressing both fishing and fish farming, will be addressed, explained and discussed. The use of underwater robots for cleaning the aquaculture nets is addressed in the first part of the paper. Fish farming suffers from biofouling which can hurt fish, increase mortality and consequently reduce production. It is necessary to clean the nets in order to sustain the flow of oxygen-rich water through the cage. The conventional methods of cleaning, primarily manual cleaning, is quite time-consuming requiring extensive men-hours. The overview of several new systems, based on high pressure cleaning, that hit the market recently, is given.. They rely on heavy equipment making these systems unusable for small producers. The novel approach and methods in cleaning are needed. The discussion on strategy and economy on introducing ultrasonic underwater robot in cleaning and prevention of biofouling build-up is given in detail. The second part of the paper deals with surveying and monitoring potentially protected marine areas in order to manage them more efficiently. Regular and frequent monitoring of marine environment results in estimating the amount of biomass in it as well as the water conditions. Regular monitoring may result in determining the amount of protected areas reserved for spawning of fish. It would allow determine when certain spices of fish spawn. Gathered knowledge helps in better management of the underwater resources and may determine the length of the period when fishing is to be allowed as well as amount of total biomass of the fish that is to be fished out from the sea. Monitoring also allows determining the impact of fishing and fish farms to environment.

The present state of the underwater robotics is described, with examples of major market drivers. Autonomous and remotely operated unmanned underwater vehicles is described with their use in various application domains. The future development and expectations for underwater robots is presented. The paper gives a short overview of present FP7 and international projects in underwater robotics. Role and achievements in the Laboratory for underwater systems and technologies is also given.

Mediterranean « tartana» type of trawl is the main bottom trawl design in the Adriatic. It is used evenly on Croatian side as well as on Italian side of the Adriatic, but also in many other Mediterranean countries. Due to its construction and small mesh size, « tartana» bottom trawl is unselective and presumed as inadequate for works on subject of selectivity. Therefore, new designs of bottom trawl, based on double panel trawl designs, have been constructed in order to allow proper research on bottom trawl selectivity. During research, underwater video camera has been used and some technical parametars of trawls have been observed. Results of those observations, from four different trawl constructions, have been presented in this paper.