Bioacoustics at present seems very split into two camps, terrestrial & marine/aquatic and it doesn't seem like there is as much collaboration between the two as there could be given the opportunities for interdisciplinary work! Does anyone know of projects or papers that have jointly addressed questions by combining the two? Or any other initiatives aimed at building connections between the two "camps"? I think there is a lot of opportunity there but from my own internet searching it doesn't seem like it has been done much. Thanks!
There have been numerous workshops that have included bioacousticians from both the terrestrial & aquatic realm.
The 'Bio-acoustics as indicators of population structure: Data, techniques, and inferences' workshop hosted by the National Institute for Mathematical and Biological Synthesis (co-hosted by myself & genetics colleague Eric Archer) included scientists studying a wide variety of taxa. Two of the intended products from this workshop might be of interest:
(1) Gentry, K.E., Lewis, R.N., Glanz, H., Simões, P.I., Nyári, Á.S. and Reichert, M.S., 2020. Bioacoustics in cognitive research: Applications, considerations, and recommendations. Wiley Interdisciplinary Reviews: Cognitive Science, 11(5), p.e1538.
(2) Bioacoustics Stack Exchange (this site!). During the workshop it was evident that there was an incredible need for a public forum for Q&A to allow scientists to keep up with the rapidly evolving field. We also saw that this could serve as a great avenue towards finding more common ground between terrestrial & aquatic bioacousticians.
The Acoustical Society of America Animal Bioacoustics Technical Committee is a great venue to discuss and encourage such collaboration. It's one of the few places I've been exposed to research on baleen whales, frogs, bats, and insects in one morning. It's a longer-term objective but perhaps proposing a session on cross-domain collaboration would be of interest.
Given the increasing interest in applying soundscape acoustic indices to marine environments (originally developed for terrestrial work), perhaps this topic offers a means of collaboration between the two realms! But of course, would need to be focused more on the general trends as opposed to absolute values.
You may already know of these papers, which attempted common analyses for terrestrial and marine recordings:
Buxton et al (2018) "Efficacy of extracting indices from large-scale acoustic recordings to monitor biodiversity" Conservation Biology, https://conbio.onlinelibrary.wiley.com/doi/pdf/10.1111/cobi.13119 From the Abstract: "For [temperate] terrestrial recordings, random-forest models with a suite of acoustic indices as covariates predicted Shannon diversity, richness, and total number of biological sounds with high accuracy... [but for tropical] marine recordings, random-forest models poorly predicted Shannon diversity, richness, and total number of biological sounds"
Gottesman et al (2021) "What does resilience sound like? Coral reef and dry forest acoustic communities respond differently to Hurricane Maria" Ecological Indicators, https://www.sciencedirect.com/science/article/pii/S1470160X21003009 From the Abstract: "While the coral reef communities exhibited high resistance to the storm, all sound types within the dry forest were significantly impacted, with two of the three insect choruses and bird vocalizations at dawn declining approximately 50% in the weeks following Hurricane Maria"
So there is certainly potential, although the methodology needs some careful thought. I think there's a lot of potential in investigating common responses to e.g., habitat disturbance, anthropogenic pressures etc.
If one ignores the different sensors and different environmental challenges, there are a lot of common approaches. Especially in signal processing. Obviously one must learn to accept that there are still differences that favour different methods. For example: Multipath ranging is easier in marine environment than in terrestrial setting. Neural Networks seem to have better success in bird classification than for cetacean clicks (I know there are publications on that).
I think there are many opportunities here, especially if you are interested in taking a comparative approach. Comparative studies that look at multiple (groups of) species are very valuable if we want to understand how communication systems evolved. This allows us to look for similarities and differences, and make inferences based on those. For example, there is a growing body of research on vocal learning (i.e., the ability to learn/modify sounds). This trait has been observed in birds (songbirds, parrots, hummingbirds), cetaceans, pinnipeds, bats, elephants, and humans, and possibly more! A good place to start could be the themed issue from the Philosophical Transactions of the Royal Society B published last year.