The sound of communication in underwater acoustic sensor networks: (Position paper)

Underwater environments have never been much of a constraint to the rich animal life they support at all depths of our seas and oceans. Indeed, nature has taken advantage of this environment to develop a rich variety of efficient communication strategies through evolutionary change and adaptation. The wealth of knowledge to be discovered will continue to dazzle and fascinate the world. For underwater sensor network communication, acoustic signalling is the preferred choice for designers because sound propagation is the most efficient when compared to other forms, like thermal, light, and electromagnetic. It is within this acoustic environment that researchers have to innovate and develop new ideas and methodologies so as to advance the state-of-the-art. In this paper, several fundamental issues and connections are discussed that arise in the study of underwater wireless sensor networks. A variety of ideas and solutions for further research is proposed and fundamental issues in topology control, directional underwater transducers, and monitoring and surveillance are disc

Disentangling defense: the function of spiny lobster sounds

The function of anti-predator signalling is a complex, and often-overlooked, area of animal communication. The goal of this study was to examine the behavioural function of an anti-predator acoustic signal in the ocean. We observed the acoustic and defensive behaviours of California spiny lobsters (Palinuridae: Panulirus interruptus) to a model predator, model conspecific and blank pole, both in the tank and in the field. We found that P. interruptus make a ‘rasp ’ sound once physically contacted by an aggressor, rather than during the approach. The model predator and conspecific elicited no discernable changes in defensive behaviour, but the responses by the lobsters to aggressors in the tank versus field were distinct. Our results indicate that the spiny lobster’s rasp is used as a startle or aposematic signal, which may be coupled with visual aposematism of their spines. Alternatively, the rasp may function as a vibratory escape mechanism or as an acoustic analogue to eye-spots. This study offers insights into the role of acoustic signalling in the marine environment and demonstrates a central role for sound production in spiny lobster ecology

Connectivity of the Gulf of Mexico Continental Shelf Fish Populations and Implications of Simulated Oil Spills

The Gulf of Mexico (GoM) marine ecosystem is experiencing acute stressors. Natural (e.g., hurricanes, harmful algal blooms) or anthropogenic (e.g., oil spills), these stressors have the potential to impact fish populations and decrease biodiversity that may be difficult to recover unless the ecosystem is resilient. One of the most effective factors governing the resilience capacity of sensitive Gulf fish species is the degree of connectivity and network modularity among spatial sub-units of species occupying the continental shelf. This chapter is a meta-study that looks at the relationship between the Lagrangian dynamical geography of the GoM regions, the community structure of demersal fish, and the potential for larval connectivity. We use adult fish movement from tagging data, larval fish migration from biophysical modeling, and oceanographic patterns from satellite-tracked Lagrangian drifters to quantify the degree of connectivity and modularity of the GoM ecosystem. We evaluate the biophysical model output with 20+ years of data from the Southeast Area Monitoring and Assessment Program (SEAMAP) ichthyoplankton survey and use the drifter inferred dynamics provinces to access mechanisms underlying retention or exchange for each species and GoM province. The tagging analyses reveal a modular network structure consistent with the Lagrangian oceanographic provinces. While the oceanographic dynamic patterns drive self-recruitment levels and the size and location of these provinces, they do not constrain connectivity patterns between distant locations within the GoM. In contrast, larval transport and migration between the provinces and subregions drive the patterns of connectivity and community structure similarity. Ultimately, it is the combination of within-scale functional redundancy and cross-scale species connectivity that can amplify resilience and speed of recovery and minimize the potential for catastrophic regime shifts in ecological meta-communities such as in the GoM. The importance of such studies to natural resource management and oil spill preparedness outcomes is discussed