The necessity for carbon unites all known life forms and thus, the processes that steer the movement of carbon throughout ecosystems play a pivotal role in determining how biota manifests itself. Decomposers serve a fundamental part in the recycling of carbon and their breakdown of large organic matter, such as leaf litter from terrestrial and aquatic plants, is well known to be a primary source of nutrient in streams. In contrast, there is a prominent gap in knowledge when it comes to the importance of large organic matter in coastal marine systems and what factors influence its decomposition. Hence, the purpose of this study is to advance our understanding of leaf litter decomposition in the environmental conditions mentioned above. Focus was put on three abiotic factors: temperature, wave turbulence, and mesh size of litter bags. Birch leaves were used as this is a common tree species in coastal Baltic systems and the experiment took place in a laboratory setting. Buckets filled with brackish seawater were put in constant temperature rooms either set to 6°C or 14°C, and turbulence was created by a motorized swing. Microbes were the only organism present in the water. Plastic mesh bags were crafted, that had either coarse or fine mesh size (7 mm and 0,5 mm respectively). Incubation period was a maximum of six weeks, with samples being collected every fortnight. Results showed that treatments in higher temperatures and with fine mesh size to have lost significantly more leaf mass compared to their counterparts, while turbulence had no effect. Leaves lost the most substantial amount of weight during the first two weeks, likely due to leaching. Other studies have suggested that climate warming might change decomposer composition to increase microbes and reduce larger detrivores, and potentially increase total decomposition rate. Turbulence had no effect on weight loss, yet non-present decomposers such as shredders are important factors that might interact with turbulence to impact degradation in natural systems. The higher weight loss in fine mesh compared to coarse mesh could potentially be explained by its larger effective surface area on which microbes can colonize. It is important to note that laboratory experiments with a few select parameters might not reflect the full behavior or implications of influences, which highlights the importance of unison between studies conducted in laboratories and natural settings. Suggestions for future research would be to study the role of leaf litter in coastal habitats and not just the factors affecting it.