Correction: Boat noise interferes with Lusitanian toadfish acoustic communication

Anthropogenic noise is considered a major underwater pollutant as increasing ocean background noise due to human activities is impacting aquatic organisms. One of the most prevalent anthropogenic sounds is boat noise. Although motorboat traffic has increased in the past few decades, its impact on the communication of fish is still poorly known. The highly vocal Lusitanian toadfish (Halobatrachus didactylus) is an excellent model to test the impact of this anthropogenic stressor as it relies on acoustic communication to attractmates.Here,we performed two experiments to test the impact of boat noise on the acoustic communication of the Lusitanian toadfish. Using the auditory evoked potential (AEP) technique, we first compared the maximum distance a fish can perceive a boatwhistle (BW), the mate attraction acoustic signal, before and after embedding it in boat noise. Noises from a small motorboat and from a ferryboat reduced the active space from a control value of 6.4–10.4 m to 2.0–2.5 m and 6.3–6.7 m, respectively. In the second experiment we monitored the acoustic behaviour of breeding males exposed to boat noise playbacks and we observed an increase in the inter-onset interval ofBWs and a disruption of the usual vocal interactions between singing males. These results demonstrate that boat noise can severely reduce the acoustic active space and affect the chorusing behaviour in this species, which may have consequences in breeding success for individuals and could thus affect fitness.info:eu-repo/semantics/publishedVersio

Underwater noise recognition of marine vessels passages: two case studies using hidden Markov models

Passive acoustic monitoring (PAM) is emerging as a cost-effective non-intrusive method to monitor the health and biodiversity of marine habitats, including the impacts of anthropogenic noise on marine organisms. When long PAM recordings are to be analysed, automatic recognition and identification processes are invaluable tools to extract the relevant information. We propose a pattern recognition methodology based on hidden Markov models (HMMs) for the detection and recognition of acoustic signals from marine vessels passages and test it in two different regions, the Tagus estuary in Portugal and the Öresund strait in the Baltic Sea. Results show that the combination of HMMs with PAM provides a powerful tool to monitor the presence of marine vessels and discriminate different vessels such as small boats, ferries, and large ships. Improvements to enhance the capability to discriminate different types of small recreational boats are discussed.info:eu-repo/semantics/publishedVersio

Characterization of the acoustic community of vocal fishes in the Azores

Sounds produced by teleost fishes are an important component of marine soundscapes, making passive acoustic monitoring (PAM) an effective way to map the presence of vocal fishes with a minimal impact on ecosystems. Based on a literature review, we list the known soniferous fish species occurring in Azorean waters and compile their sounds. We also describe new fish sounds recorded in Azores seamounts. From the literature, we identified 20 vocal fish species present in Azores. We analysed long-term acoustic recordings carried out since 2008 in Condor and Princesa Alice seamounts and describe 20 new putative fish sound sequences. Although we propose candidates as the source of some vocalizations, this study puts into evidence the myriad of fish sounds lacking species identification. In addition to identifying new sound sequences, we provide the first marine fish sound library for Azores. Our acoustic library will allow to monitor soniferous fish species for conservation and management purposes.info:eu-repo/semantics/publishedVersio

Patterns of colonization and species distribution for Azorean arthropods: evolution, diversity, rarity and extinction

Proceedings of the Symposium "Darwin's Mistake and what we are doing to correct it". Ponta Delgada, 19-22 September, 2009.Com base em estudos ecológicos e biogeográficos realizados nos Açores (um arquipélago remoto composto por nove ilhas vulcânicas) durante muitos anos de uma forma continuada, apresentamos um conjunto de questões. O grupo alvo são os artrópodes e o principal habitat é a Laurissilva, a floresta nativa dos Açores. A diversificação das espécies de artrópodes dos Açores é afectada pela idade das ilhas, área das ilhas e seu isolamento. No entanto, os estudos que decorreram durante os últimos dez anos mostram que os vários tipos de grupos taxonómicos e ecológicos são afectados de forma diferente por estes factores, tendo como consequência padrões de distribuição espacial únicos. A distribuição espacial dos artrópodes em cada ilha é causada for "efeitos de massa", muitas espécies possuindo dinâmicas "fonte-sumidouro". As espécies verdadeiramente raras à escala regional são aquelas que são especialistas de um particular habitat, muitas delas sendo espécies endémicas ameaçadas. Embora várias espécies endémicas persistam com populações sumidouro em habitats criados pelo Homem (e.g. florestas exóticas), mais de metade das espécies especialistas da floresta nativa já estão extintas ou poderão extinguir-se no futuro. De facto, aquelas espécies que evoluíram e apenas são encontradas nas florestas nativas foram afectadas de forma dramática como resultado da destruição alargada das florestas nativas dos Açores. Defendemos que a única forma de evitar a extinção de uma fauna única das florestas nativas dos Açores será através de medidas de restauro desta floresta.ABSTRACT: Here we address a list of questions based on long-term ecological and biogeographical studies performed in the Azores, a remote volcanic oceanic archipelago composed by nine islands. The target group are the arthropods, and the main habitat the Laurisilva, the Azorean native forest. Diversification of Azorean arthropod species is affected by island age, area and isolation. However, results obtained for over a decade show that distinct groups are differently affected by these factors, which has lead to the extreme diverse distribution patterns currently observed. Spatial distribution of arthropods in each island may be interpreted as caused by a typical "mass effect", with many species following a "source-sink" dynamics. Truly regionally rare species are those that are habitat specialists, many of them being threatened endemic species. Although various endemics persist as sink populations in human-made habitats (e.g., exotic forests), more than half of the original endemic forest arthropods may already have vanished or may eventually be driven to extinction in the future. Those species which have evolved in and are mainly found in native forests, have been dramatically affected by hitherto unrecognized levels of extinction debt, as a result of extensive destruction of native forest. We argue that immediate action to restore and expand native forest habitat is required to avoid a future of disastrous extinctions of a biologically unique fauna with an unique evolutionary history

Noise Affects Multimodal Communication During Courtship in a Marine Fish

Selection pressures on signals can be substantially modified by a changing environment, but we know little about how modified selection pressures act on multimodal signals. The currently increasing levels of anthropogenic noise in the ocean may affect the use of acoustic signaling relative to other modalities. In the Painted Goby (Pomatoschistus pictus), visual and acoustic signals are associated during courtship behavior, but females usually rely more heavily on acoustic signals than on visual signals in mate choice. In an aquarium experiment, we compared male courtship behavior and female spawning decisions between silent treatments and treatments with additional noise. We found that the relationships between male characteristics, male visual and acoustic courtship, and spawning success were affected by noise. A path analysis revealed that females pay more attention to visual courtship in noisy circumstances compared to control. We conclude that environmental stressors can cause shifts in the use of different signaling modalities for spawning decisions and discuss how selection pressures on multimodal signals may change with increasing noise-levels

Ranking protected areas in the Azores using standardised sampling of soil epigean arthropods

Copyright © Springer 2005.Nineteen areas in seven of the nine Azorean islands were evaluated for species diversity and rarity based on soil epigean arthropods. Fifteen out of the 19 study areas are managed as Natural Forest Reserves and the remaining four were included due to their importance as indigenous forest cover. Four of the 19 areas are not included in the European Conservation network, NATURA 2000. Two sampling replicates were run per study area, and a total of 191 species were collected; 43 of those species (23%) are endemic to the archipelago and 12 have yet to be described. To produce an unbiased multiple-criteria index (importance value for conservation, IV-C) incorporating diversity and rarity based indices, an iterative partial multiple regression analysis was performed. In addition, an irreplaceability index and the complementarity method (using both optimisation and heuristic methods) were used for priority-reserves analyses. It was concluded that at least one well-managed reserve per island is absolutely necessary to have a good fraction of the endemic arthropods preserved. We found that for presence/absence data the suboptimal complementarity algorithm provides solutions as good as the optimal algorithm. For abundance data, optimal solutions indicate that most reserves are needed if we want that at least 50% of endemic arthropod populations are represented in a minimum set of reserves. Consistently, two of the four areas not included in the NATURA 2000 framework were considered of high priority, indicating that vascular plants and bird species used to determine NATURA 2000 sites are not good surrogates of arthropod diversity in the Azores. The most irreplaceable reserves are those located in older islands, which indicates that geological history plays an important role in explaining faunal diversity of arthropods in the Azores. Based both on the uniqueness of species composition and high species richness, conservation efforts should be focused on the unmanaged Pico Alto region in the archipelago’s oldest island, Santa Maria

Communication in troubled waters: Responses of fish communication systems to changing environments

Fish populations are increasingly being subjected to anthropogenic changes to their sensory environments. The impact of these changes on inter- and intra-specific communication, and its evolutionary consequences, has only recently started to receive research attention. A disruption of the sensory environment is likely to impact communication, especially with respect to reproductive interactions that help to maintain species boundaries. Aquatic ecosystems around the world are being threatened by a variety of environmental stressors, causing dramatic losses of biodiversity and bringing urgency to the need to understand how fish respond to rapid environmental changes. Here, we discuss current research on different communication systems (visual, chemical, acoustic, electric) and explore the state of our knowledge of how complex systems respond to environmental stressors using fish as a model. By far the bulk of our understanding comes from research on visual communication in the context of mate selection and competition for mates, while work on other communication systems is accumulating. In particular, it is increasingly acknowledged that environmental effects on one mode of communication may trigger compensation through other modalities. The strength and direction of selection on communication traits may vary if such compensation occurs. However, we find a dearth of studies that have taken a multimodal approach to investigating the evolutionary impact of environmental change on communication in fish. Future research should focus on the interaction between different modes of communication, especially under changing environmental conditions. Further, we see an urgent need for a better understanding of the evolutionary consequences of changes in communication systems on fish diversity

Call recognition and individual identification of fish vocalizations based on automatic speech recognition: An example with the Lusitanian toadfish

The study of acoustic communication in animals often requires not only the recognition of species specific acoustic signals but also the identification of individual subjects, all in a complex acoustic background. Moreover, when very long recordings are to be analyzed, automatic recognition and identification processes are invaluable tools to extract the relevant biological information. A pattern recognition methodology based on hidden Markov models is presented inspired by successful results obtained in the most widely known and complex acoustical communication signal: human speech. This methodology was applied here for the first time to the detection and recognition of fish acoustic signals, specifically in a stream of round-the-clock recordings of Lusitanian toadfish (Halobatrachus didactylus) in their natural estuarine habitat. The results show that this methodology is able not only to detect the mating sounds (boatwhistles) but also to identify individual male toadfish, reaching an identification rate of ca. 95%. Moreover this method also proved to be a powerful tool to assess signal durations in large data sets. However, the system failed in recognizing other sound types.Fundação para a Ciência e a Tecnologia (FCT