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Valve gape monitors are utilised to measure the extent of bivalve's shell openings. This measurement is correlated with their filter-feeding activity, and valve closure can serve as an indicator of various environmental stressors, including poor water quality, the presence of predators, and human disturbance. We developed an inexpensive, stand-alone, and reusable valve gape monitor; enabling collection of sufficient and independent spatial replication in situ. The monitor is made using Arduino hardware and software, and we share the design and code. We tested it in the field with three mussels as a proof of concept. The mussels were likely actively feeding most of the time. Two of the mussels were in close vicinity and demonstrated similar valve gape patterns. The monitor enables to measure valve gape in high resolution, providing insights into bivalve biology, ecosystem functioning, and the effects of environmental conditions, including anthropogenic stressors.

Sound exposure studies require replicated sound treatments for the results to be representative for sound classes in general. Additionally, reused treatments in replicated designs need to be accounted for statistically. The lack hereof is referred to as simple and sacrificial pseudoreplication, respectively, and results should be interpreted accordingly. We quantified the occurrence of these issues and subsequent interpretation of results in 104 underwater sound exposure studies (2019–2023). The majority of the studies (85%) did not replicate sound treatments. From the ones that did, most did not statistically acknowledge the hierarchical structure of the data. Unreplicated treatment designs limit the generalizability of the findings. Nevertheless, only small differences were found in how the results of unreplicated and replicated treatment designs were interpreted. This commentary aims to provide guidance in the design, analysis and interpretation of sound exposure studies, which are equally valid for aquatic and terrestrial research.

Acoustic deterrent devices are used to guide aquatic animals from danger or toward migration paths. At sea, moderate sounds can potentially be used to deter fish to prevent injury or death due to acoustic overexposure. In sound exposure studies, acoustic features can be compared to improve deterrence efficacy. In this study, we played 200–1600 Hz pulse trains from a drifting vessel and investigated changes in pelagic fish abundance and behavior by utilizing echosounders and hydrophones mounted to a transect of bottom-moored frames. We monitored fish presence and tracked individual fish. This revealed no changes in fish abundance or behavior, including swimming speed and direction of individuals, in response to the sound exposure. We did find significant changes in swimming depth of individually tracked fish, but this could not be linked to the sound exposures. Overall, the results clearly show that pelagic fish did not flee from the current sound exposures, and we found no clear changes in behavior due to the sound exposure. We cannot rule out that different sounds at higher levels elicit a deterrence response; however, it may be that pelagic fish are just more likely to respond to sound with (short-lasting) changes in school formation.

Data abstract: All data and scripts to replicate all plots and statistical results of the paper mentioned below. The data are sound recordings and processed echosounder data (raw echosounder data is available on request but > 100 GB in size and require specialized software). Paper reference: Jeroen Hubert, Jozefien M. Demuynck, M. Rafa Remmelzwaal, Carlota Muñiz, Elisabeth Debusschere, Benoit Berges, Hans Slabbekoorn; An experimental sound exposure study at sea: No spatial deterrence of free-ranging pelagic fish. J. Acoust. Soc. Am. 1 February 2024; 155 (2): 1151–1161. https://doi.org/10.1121/10.0024720 Paper abstract: Acoustic deterrent devices are used to guide aquatic animals from danger or toward migration paths. At sea, moderate sounds can potentially be used to deter fish to prevent injury or death due to acoustic overexposure. In sound exposure studies, acoustic features can be compared to improve deterrence efficacy. In this study, we played 200–1600 Hz pulse trains from a drifting vessel and investigated changes in pelagic fish abundance and behavior by utilizing echosounders and hydrophones mounted to a transect of bottom-moored frames. We monitored fish presence and tracked individual fish. This revealed no changes in fish abundance or behavior, including swimming speed and direction of individuals, in response to the sound exposure. We did find significant changes in swimming depth of individually tracked fish, but this could not be linked to the sound exposures. Overall, the results clearly show that pelagic fish did not flee from the current sound exposures, and we found no clear changes in behavior due to the sound exposure. We cannot rule out that different sounds at higher levels elicit a deterrence response; however, it may be that pelagic fish are just more likely to respond to sound with (short-lasting) changes in school formation., Data abstract: All data and scripts to replicate all plots and statistical results of the paper mentioned below. The data are sound recordings and processed echosounder data (raw echosounder data is available on request but > 100 GB in size and require specialized software). Paper reference: Jeroen Hubert, Jozefien M. Demuynck, M. Rafa Remmelzwaal, Carlota Muñiz, Elisabeth Debusschere, Benoit Berges, Hans Slabbekoorn; An experimental sound exposure study at sea: No spatial deterrence of free-ranging pelagic fish. J. Acoust. Soc. Am. 1 February 2024; 155 (2): 1151–1161. https://doi.org/10.1121/10.0024720 Paper abstract: Acoustic deterrent devices are used to guide aquatic animals from danger or toward migration paths. At sea, moderate sounds can potentially be used to deter fish to prevent injury or death due to acoustic overexposure. In sound exposure studies, acoustic features can be compared to improve deterrence efficacy. In this study, we played 200–1600 Hz pulse trains from a drifting vessel and investigated changes in pelagic fish abundance and behavior by utilizing echosounders and hydrophones mounted to a transect of bottom-moored frames. We monitored fish presence and tracked individual fish. This revealed no changes in fish abundance or behavior, including swimming speed and direction of individuals, in response to the sound exposure. We did find significant changes in swimming depth of individually tracked fish, but this could not be linked to the sound exposures. Overall, the results clearly show that pelagic fish did not flee from the current sound exposures, and we found no clear changes in behavior due to the sound exposure. We cannot rule out that different sounds at higher levels elicit a deterrence response; however, it may be that pelagic fish are just more likely to respond to sound with (short-lasting) changes in school formation.

Noisy human activities at sea are changing the acoustic environment, which has been shown to affect marine mammals and fishes. Invertebrates, such as bivalves, have so far received limited attention despite their important role in the marine ecosystem. Several studies have examined the impact of sound on anti-predator behavior using simulated predators, but studies using live predators are scarce. In the current study, we examined the separate and combined effects of boat sound playback and predator cues of shore crabs (Carcinus maenas) on the behavior of mussels (Mytilus spp.). We examined the behavior of the mussels using a valve gape monitor and scored the behavior from the crabs in one of two types of predator test conditions from video footage to control for effects from potential, sound-induced variation in crab behavior. We found that mussels closed their valve gape during boat noise and with a crab in their tank, but also that the stimulus combination did not add up to an even smaller valve gape. The sound treatment did not affect the stimulus crabs, but the behavior of the crabs did affect the valve gape of the mussels. Future research is needed to examine whether these results stand in situ and whether valve closure due to sound has fitness consequences for mussels. The effects on the well-being of individual mussels from anthropogenic noise may be relevant for population dynamics in the context of pressure from other stressors, their role as an ecosystem engineer, and in the context of aquaculture.

A specimen of the endemic New Zealand lancelet Epigonichthys hectori (Benham, 1901) was found and photographed in the intertidal area of a beach near the Whangarei Heads in New Zealand. This only lancelet species for New Zealand is rarely caught and is known for its specific habitat requirements, demanding clean, coarse sand. The specimen was found in an almost dried-out puddle during low tide on a beach with a lot of human activity. The species is also known to inhabit greater depths, making this observation (together with another recent, unpublished record) a constitution for evidence that it also inhabits tidal areas. Distribution records from the literature are reviewed, plotted on a map, and supplemented by this new observation.

BackgroundThe Rapid Arterial oCclusion Evaluation (RACE) score can identify patients with anterior circulation large‐vessel occlusion (aLVO) ischemic stroke for transportation to a comprehensive stroke center for endovascular thrombectomy. However, patients with intracranial hemorrhage (ICH) may also benefit from direct transportation to a comprehensive stroke center for neurosurgical treatment. We aimed to assess if the RACE score can distinguish patients with ICH in addition to aLVO stroke from other patients with suspected stroke.MethodsWe analyzed data from the LPSS (Leiden Prehospital Stroke Study), a multicenter, prospective, observational cohort study in 2 Dutch ambulance regions. Ambulance paramedics documented prehospital observations in all patients aged ≥18 years with suspected stroke. We calculated the sensitivity, specificity, positive predictive value, and negative predictive value of a positive RACE score (≥5 points) for a diagnosis of ICH or aLVO stroke, compared with patients with non‐aLVO stroke, transient ischemic attack, or stroke mimic. In addition, we performed a multivariable logistic regression analysis and calculated adjusted odds ratios (ORs).ResultsWe included 2004 patients with a stroke code, of whom 149 had an ICH, 153 had an aLVO stroke, 687 had a non‐aLVO stroke, 262 had a transient ischemic attack, and 753 had a stroke mimic. Patients with ICH and aLVO stroke more often had a positive RACE score than other patients with suspected stroke (46.2% and 58.0%, respectively, versus 6.4%; P<0.01). A positive RACE score had a sensitivity of 52.7%, a specificity of 93.6%, a positive predictive value of 55.4%, and a negative predictive value of 92.9% for a diagnosis of ICH or aLVO stroke. In multivariable analysis, a positive RACE score had the strongest association with ICH or aLVO stroke (adjusted OR, 10.11 [95% CI, 6.84–14.93]).ConclusionsOur study shows that the RACE score can also identify patients with ICH in addition to aLVO stroke. This

Anthropogenic sound has increasingly become part of the marine soundscape and may negatively affect animals across all taxa. Invertebrates, including bivalves, received limited attention even though they make up a significant part of the marine biomass and are very important for higher trophic levels. Behavioural studies are critical to evaluate individual and potentially population-level impacts of noise and can be used to compare the effects of different sounds. In the current study, we examined the effect of impulsive sounds with different pulse rates on the valve gape behaviour and phytoplankton clearance rate of blue mussels (Mytilus spp.). We monitored the mussels' valve gape using an electromagnetic valve gape monitor and their clearance rate using spectrophotometry of phytoplankton densities in the water. We found that the mussels' valve gape was positively correlated with their clearance rate, but the sound exposure did not significantly affect the clearance rate or reduce the valve gape of the mussels. They did close their valves upon the onset of a pulse train, but the majority of the individuals recovered to pre-exposure valve gape levels during the exposure. Individuals that were exposed to faster pulse trains returned to their baseline valve gape faster. Our results show that different sound exposures can affect animals differently, which should be taken into account for noise pollution impact assessments and mitigation measures.

Effects of a full-scale seismic survey experiment on the movement behaviour of Atlantic cod.

Energy intake and expenditure data are needed to estimate population level effects of anthropogenic sound on fish. We present an experimental design of a controlled behavioral experiment that allows to collect relatively long-term data (days) on Atlantic cod (Gadus morhua) during sound exposures. Data on the time spent foraging and swimming can be used as proxies for energy intake and expenditure. The wild-caught but captive Atlantic cod exhibited natural foraging behavior in the experimental basins and the design allowed for efficient scoring of the behavior throughout the 6-day trials. We conducted three pilot trials and share the experimental design to encourage other researchers to collect data on (proxies for) energy intake and expenditure to aid estimation of population level effects of sound exposures from noisy human activities such as seismic surveys.

While humans can easily entrain their behavior with the beat in music, this ability is rare among animals. Yet, comparative studies in non-human species are needed if we want to understand how and why this ability evolved. Entrainment requires two abilities: (1) recognizing the regularity in the auditory stimulus and (2) the ability to adjust the own motor output to the perceived pattern. It has been suggested that beat perception and entrainment are linked to the ability for vocal learning. The presence of some bird species showing beat induction, and also the existence of vocal learning as well as vocal non-learning bird taxa, make them relevant models for comparative research on rhythm perception and its link to vocal learning. Also, some bird vocalizations show strong regularity in rhythmic structure, suggesting that birds might perceive rhythmic structures. In this paper we review the available experimental evidence for the perception of regularity and rhythms by birds, like the ability to distinguish regular from irregular stimuli over tempo transformations and report data from new experiments. While some species show a limited ability to detect regularity, most evidence suggests that birds attend primarily to absolute and not relative timing of patterns and to local features of stimuli. We conclude that, apart from some large parrot species, there is limited evidence for beat and regularity perception among birds and that the link to vocal learning is unclear. We next report the new experiments in which zebra finches and budgerigars (both vocal learners) were first trained to distinguish a regular from an irregular pattern of beats and then tested on various tempo transformations of these stimuli. The results showed that both species reduced the discrimination after tempo transformations. This suggests that, as was found in earlier studies, they attended mainly to local temporal features of the stimuli, and not to their overall regularity. However, some indiv