Wang, ShenghaoShenghaoWang2025-10-132025-10-132025-08-19https://media.suub.uni-bremen.de/handle/elib/22802https://doi.org/10.26092/elib/4522Anthropogenic underwater noise is by no means a novel pollutant and with the ever-increasing volume of marine traffic as well as other offshore human activities such as wind energy and natural resource extraction, the oceanic ambient sound levels are set to continue rising. While research on anthropogenic noise effects on marine mammals and fish spans over half a century, similar research for marine invertebrates has only started gaining traction in the last one to two decades. Consequently, marine invertebrates remain critically understudied in this regard. These organisms are crucial ecosystem components due to their roles in influencing sediment dynamics, benthic production, and constituting key prey for higher trophic levels among others. The few published studies to date highlight that anthropogenic noise can negatively affect invertebrate behavior as well as physiology. Considering the multitude of vital roles invertebrates play in their respective ecosystems and the continuously rising sound levels in the ocean, more exploratory research is urgently needed. This thesis investigated the effect of anthropogenic, continuous low-frequency noise (CLFN) on invertebrate model systems from different benthic communities typical of the North Atlantic coasts. The overarching objective was addressed through five controlled laboratory experiments, each examining the potential implications of CLFN within a distinct biotope. These implications were explored through the effects of CLFN on key behaviors and/or physiological parameters involved in model systems from respective benthic communities. Experimental findings were put into context by quantifying the sound levels and vessel prevalences of a typical nearshore environment in which the different communities may be found. Infaunal communities are composed of invertebrates that live within the seafloor sediment. These invertebrates continuously disrupt the sediment they inhabit through activities such as burrowing and ventilating and thereby influence local sediment dynamics and biogeochemistry. Chapter 2 & 3 investigated how CLFN affects the sediment reworking and bioirrigation activities of four macrobenthic invertebrates. Chapter 2 demonstrated that added noise reduced burrowing by the amphipod crustacean Corophium volutator. The bivalve Macoma balthica exhibited a potential stress response while the polychaete Arenicola marina showed greater variability in irrigation rates. Chapter 3 further revealed that added noise reduced the ventilation (and thus, bioirrigation) rate and disrupted the ventilation pattern of the polychaete Lanice conchilega. These findings demonstrate how bioturbation, a crucial benthic process, can be impacted by anthropogenic noise. If sustained, outward-rippling effects on the local sediment dynamics and biogeochemistry may be possible. Mesograzing communities are characterized by small, herbivorous invertebrates that live among and graze on macrophyte assemblages. Not only do these mesograzers control macrophyte growth and assemblage structure through their grazing, but they also facilitate the transfer of primary production. Chapter 4 investigated how CLFN affected the metabolism and energy pathways of two crustacean mesograzers. The amphipod Gammarus locusta exhibited greatly reduced oxygen consumption rates with no changes in metabolic enzyme activities while the isopod Idotea balthica appeared robust to CLFN in these aspects. Chapter 5 further investigated how CLFN affected the feeding performance and habitat choice as well as the metabolism and energy pathways of the amphipod Marinogammarus marinus. Added noise reduced feeding rate and overall consumption of algal material and elevated the activity of an enzyme often used to estimate respiratory rate, suggesting increased oxygen consumption and metabolism. These findings indicate the potential interference of CLFN with processes integral to the top-down control of macrophyte growth by mesograzers, which may result in ecosystem-wide shifts such as community restructuring depending on effect severity. Mussel bed communities are formed when mussels aggregate using byssal threads on hard substrate. These beds provide biogenic substrate for other organisms, thereby constituting biodiversity hotspots to the neighboring communities. Chapter 6 investigated how CLFN, as well as the interactive effect of noise and predator cues, affect the byssal thread production of blue mussels of the Mytilus edulis complex. Mytilus produced more threads in the presence of predator cues, but were ostensibly robust against CLFN in this aspect. This might explain how blue mussels so successfully colonize inherently disturbed habitats such as artificial hard substrates, indicating their continued persistence as well as expansion with offshore man-made structures. The North Sea island of Helgoland, a nature reserve rich in marine biodiversity, is surrounded by human activity. Documenting and analyzing the local sound levels are thus pivotal for marine conservation management in evaluating the anthropogenic impacts in this ecologically significant region. Chapter 7 investigated the ambient sound pressure levels and the contribution of vessels near Helgoland by deploying a hydrophone for more than a year. Overall, the surveyed site was quieter than other sites documented across the North Sea. Of the months analyzed, vessel events occurred at prevalences of up to 18% and raised the ambient sound levels by an estimated mean of 5.5 dB (4.6 dB median). The very shallow depths, however, compromise sound propagation, which meant that vessel noise from the nearby shipping lane was likely already fairly attenuated upon reaching the recorder. Sound levels inside the shipping lane are expected to be much higher during events and the impacts on fauna more severe. Given that the experimental noise treatments used in this thesis were quieter than vessels typical of the area based on source levels, the results of the experiments described in Chapters 2-6 possibly even underestimate the potential impacts found directly inside shipping lanes. This thesis demonstrates how CLFN impacts different benthic biotopes through its effects on behaviors that drive essential ecosystem processes, as well as on physiological parameters integral to the homeostasis of the invertebrates performing these behaviors. The findings underscore the importance of understanding the influence of noise on entire ecosystems and not only on the organism-level. This thesis also indicates that the impact of anthropogenic CLFN in very shallow systems typical of continental shelf regions may be more localized than that in the open ocean, accentuating the need for effect testing across a gradient of sound levels. These considerations will be essential for predicting realistic impacts of noise pollution on our changing oceans moving forward.enhttps://creativecommons.org/licenses/by/4.0/Anthropogenic noiseNoise pollutionNATURAL SCIENCES::Biology::Terrestrial, freshwater and marine ecology::Marine ecologyNorth Sea500 Science::570 Life sciences; biologyDissertation10.26092/elib/4522urn:nbn:de:gbv:46-elib228024