## 4 Discussion and Conclusions  
An integrated multifunctional sea observation and forecasting system is needed to facilitate the management of the coastal and marine environment, and it is desirable that this system be accessible to a broad class of stakeholders (scientists, policymakers, environmental practitioners, coast guard, marine emergency response services, etc.). In general, one path in this direction is the optimization of communication capabilities between oceanographic measuring instruments. In particular, current developments in sensor, AI, and wireless IoT technologies make it possible to produce low-cost Smart Drifters (linear dimensions on the order of a few tens of centimeters) that, used collectively in large numbers, allow the concept and characteristics of \"clusters\" to be introduced into marine monitoring. This is the main goal of the MARTA project. In fact, the MARTA Smart Drifter Cluster is a new concept in marine monitoring systems, using drifters that are logistically simpler than current systems based on individual drifters with satellite communication,  
Figure 10: Primary Drifter power consumption during Tellaro (La Spezia-IT) sea trial. The upper plot shows the balance between the dissipated (by the thrusters) and adsorbed (from the PV panels) current. The constant zero value means that it is lower than the threshold of \(\pm\) 0.2 A. The lower plot shows the corresponding Force and Torque values for the thrusters. with lower hardware costs, near-zero maintenance costs, energy harvesting, and reduced power consumption. The suffix \"smart\" indicates the ability of the cluster's elements to make decisions about different communication strategies (frequency of data sending, type of data sent, signal strength, synchronization process with other elements, etc.) according to different occurrences (rough sea, very expanded cluster, etc.). The MARTA Smart Drifter Cluster is optimal for sub-mesoscale and mesoscale monitoring of marine currents and for further applications for which other marine monitoring instruments (oxygen, salinity, temperature, etc.) are to be included on board. The entire system, including low-level control of thruster navigation algorithms, radio and satellite communication systems, drifter trackers, and motion predictive control, has been successfully implemented using the popular middleware Robot Operating System 2 (ROS2, [[https://docs.ros.org/en/foxy/index.html](https://docs.ros.org/en/foxy/index.html)]([https://docs.ros.org/en/foxy/index.html](https://docs.ros.org/en/foxy/index.html)) (accessed on 25 May 2023)). Another goal of the MARTA project concerns the optimization of the mechanical design, constrained by an appropriate and well-studied choice of materials for the support/floating structure of this electronic remote sensing system. This is a daunting task because, at the same time, the structure must meet stringent requirements for dynamic stability, for the ability to passively follow different sea currents (surface and/or directly wind-driven, or sub-surface) depending on different requirements, while minimizing environmental impact. Thus, the materials used must be biodegradable in a marine environment. This latter requirement is a considerable challenge, as recent studies on the degradability of the most common so-called biodegradable materials (PLA, PBAT) show that they degrade rapidly in an environment such as industrial compost, but do not behave in the same way when placed in the marine environment, either in the sea or on the beach [17]. To address this, we are testing a particular blend of corn flour thickeners, which can have degradation times (in a marine environment) of no more than six months. Some tests have been made to investigate the feasibility of using the wireless communication technology adopted for MARTA smart drifters to study the diffusion (in the sea) and the distribution of accumulation points (on the beaches) of marine debris, akin to the MLTs already quoted in the introduction [9].