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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.

The main purpose of the cruise was to study the sensory mechanisms of bioluminescence in the mesopelagic fauna. Furthermore, the presence of endogenous diel oscillators was investigated as a possible control mechanism for the daily vertical migrations of midwater animals. We conducted 20 trawls between 1,700 and 100 m depth and collected eyes and brains of mesopelagic fish for immediate experimentation on board or fixation and subsequent investigation in the home laboratories. Another major project involved the study of hadal faunal communities. Five deployments of University of Aberdeen Oceanlab autonomous landers were carried out at depths of 4,602m (control), 5,329m, 6,167m, 7,050m and 8,063m. The lander was equipped with baited traps and took time-lapse videos over a period of 12-20h after which they were recovered. Various families of fish, amphipods and snails were observed down to depth of 7,000, with abundance and number of species decreasing with depth. At 7,000m, only snailfish (liparids) came to the bait. From the video footage it would appear that liparids in the Peru-Chile Trench belong to a yet undescribed, endemic species. This confirms the hypothesis that each trench system around the Pacific Ocean is home to its own, endemic species of liparid snailfishes. The collection of amphipods and snails serves to perform population genetic studies, taxonomy and define the zonation of scavenging amphipods through the trench depths. The other, novel, instrument first deployed during this cruise is a floating platform, called Medusa, developed by J. Marshall and L. Frey for the University of Queensland, Brisbane. Medusa is also equipped with a baited camera and has spent up to 24h suspended at depths between 1,000 and 500m during four deployments. Sightings included three large Humboldt squids and numerous gelatinous and crustacean midwater fauna. The investigation of the visual systems of deep-sea fauna was focussed on teleost fishes and cephalopods. Similar approaches were used in both cases: Molecular and spectral analysis of visual pigments and the enzymes of the transduction cascade. Histological and immunocytochemical study of the morphology, including identification of neuron type diversity, and specific labelling in order to establish intraretinal and retino-tectal connectivity and synaptology. While the groups of S.Collin, J. Partridge and H.-J. Wagner concentrated mostly on visual specialists like pearleyes or lanternfishes, S.Collin also started a project to study non-visual fish such as melamphaeids of anglerfish. This will potentially identify the barely essential neural elements, a simple visual system needs to operate. It is the first time that such a wide array of different methods are applied as an integrative approach for the investigation of a sensory system in deep-sea fish The molecular mechanisms of endogenous rhythms in mesopelagic fish were also further studied. After identifying and characterising two of the clock gene family, namely per and cry from material of the last cruise we have now conducted culture experiments for 36 hours in order to monitor potential cyclic changes in the activity of these genes (H.-J. Wagner). Multibeam mapping of the ocean floor was performed routinely when entering Peruvian waters. This work is part of an ongoing project to map the topography of the ocean floor in as great detail as possible in order to better understand the processes related to the subduction zone in the Peru-Chile trench. The observations will be of use to future geophysical, geological and geochemical investigations.

BACKGROUND AND PURPOSE: MR sialography has become an alternative imaging technique for ductal salivary gland diseases. We compared the diagnostic accuracies of MR sialography and digital subtraction sialography in patients with successful completion of both examinations and benign salivary gland disorders. METHODS: In a prospective study, we attempted to examine salivary glands in 80 patients with clinically suspected diagnoses of sialadenitis and/or sialolithiasis. Each patient underwent digital subtraction sialography and MR sialography. MR sialography was obtained with a T2-weighted single-shot turbo spin-echo sequence (TR/TE 2800/1100 msec, acquisition time 7 seconds), with use of a quadrature head coil. Final diagnoses were confirmed by clinical follow-up and results of biopsy (n = 9) or surgery (n = 19). RESULTS: Failure rate was 5% (four of 80) for MR sialography and 14% (11 of 80) for digital subtraction sialography. Eighty-one salivary glands (48 parotid, 33 submandibular) in 65 patients were successfully visualized with both modalities. MR sialography depicted the main ductal system and first- and second-order branches, whereas digital subtraction sialography was able to depict third-order branches. Sensitivity and specificity to diagnose chronic sialadenitis were 70% and 98% with MR and 96% and 100% with digital subtraction sialography. MR sialography enabled diagnosis of sialolithiasis with a sensitivity of 80% and a specificity of 98% versus 90% and 98% for each with digital subtraction sialography. CONCLUSION: MR sialography with a heavily T2-weighted sequence is highly successful in the noninvasive visualization of the ductal system of major salivary glands. It is useful for diagnosing sialolithiasis and sialadenitis. Digital subtraction sialography, an invasive technique, had a substantial procedural failure rate, particularly for the submandibular duct. However, because of its higher spatial resolution, successfully completed digital subtraction sialography achieved superior diagnostic information compared with that of MR sialography.