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Marine litter is a significant and growing pollutant in the oceans. In recent years, the number of studies and initiatives trying to assess and tackle the global threat of marine litter has grown exponentially. Most of these studies, when considering macro-litter, focus on floating or stranded litter, whereas there is less information available about marine litter on the seabed. The aim of this article is to give an overview of the current state-of-the-art methods to address the issue of seafloor macro-litter pollution. The overview includes the following topics: the monitoring of macro-litter on the seafloor, the identification of possible litter accumulation hot spots on the seafloor through numerical models, and seafloor litter management approaches (from removal protocols to recycling processes). The article briefly analyzes the different approaches to involve stakeholders, since the marine litter topic is strongly related to the societal engagement. Finally, attempting to answer to all the critical aspects highlighted in the overview, the article highlights the need of innovative multi-level solutions to induce a change toward sustainable practices, transforming a problem into a real circular economy opportunity.

Different experimental trials were performed to clarify some aspects of the biology of the polychaete Hediste diversicolor (O.F. Müller, 1776) as a further step towards the development of appropriate breeding protocols for indoor farming systems. In particular, the trials were addressed to evaluate the effectiveness of two fertilization conditions (in vitro and “natural‐like”); induce gamete spawning by exposing mature individuals to thermal shock or to tissue homogenates; estimate the density effects on larval growth and survival; and evaluate the most suitable parameters to be used as proxy for biomass assessment. The highest percentages of fertilized eggs and larvae were obtained by the in vitro fertilization condition. Mature organisms were induced to spawn by exposure to thermal shock although the spawned eggs revealed low rates of fertilization and hatching. The treatment with male tissue homogenates induced females to successful spawning, and the resulting eggs showed high fertilization and hatching rates. The density of larvae in the rearing phase had no effect on growth or on survival rates of juveniles. Finally, allometric evaluations showed that fresh weight and L3 length are the most reliable parameters to be used as proxy for biomass assessment of this species.