Area-restricted searching by manta rays and their response to spatial scale in lagoon habitats

Abstract

Animals may use a variety of search patterns to locate resources when the exact locations of those resources are unknown. Theoretical and empirical evidence suggests that the optimal type of random walk will vary based on the distribution of resources such as prey. Once resources are located, the animal may utilize a movement strategy that allows it to remain within a small area and maximize resource acquisition (area-restricted searching, ARS). Detecting the location of ARS zones is important, as it identifies profitable habitat to the animal, although such analysis is rarely conducted with fishes. We utilized correlated random walk (CRW), fractal, and first passage time (FPT) analysis to quantify the response of planktivorous manta rays Manta alfredi to spatial scale and identify locations of ARS within lagoons at Palmyra Atoll. Mantas used CRWs at small spatial scales to move between prey patches, but not at larger scales as they performed home-ranging behavior. One domain was located with straighter movements at scales < 330 m, and more tortuous movements at scales > 330 m. ARS was located adjacent to ledges with high abundance of plankton, or within channels. Fractal and FPT analyses suggest that mantas used patches that were 5 to 49% of the scale of their activity space over short time periods (days). Quantitative analytical tools help explain observed patterns of movements and demonstrate the importance of lagoon habitats to these macro-planktivores.

Movements and habitat use of reef manta rays off eastern Australia: offshore excursions, deep diving and eddy affinity revealed by satellite telemetry

“…More recent telemetry studies have, for the first time, documented the movement patterns of both giant manta rays M. birostris and reef manta rays M. alfredi foraging in shallow habitats off the Yucatan Peninsula, Mexico, and in the Line Islands of the central Pacific, respectively (Graham et al 2012, Papastamatiou et al 2012. Such results have highlighted the importance of productivity blooms in inshore, coastal and coral reef ecosystems as key drivers for the spatial distributions and foraging habitats of manta rays (Graham et al 2012, Papastamatiou et al 2012.…”

“…Advances in the fields of bio-logging science, geographic information systems and ecological modelling have led to the increasing use of animal-attached sensors to remotely examine the movements, behaviour, physiology and/or biophysical habitat of a wide range of marine species (Cooke et al 2004, Ropert-Coudert et al 2009. Such studies have shed new light on the ecology of marine predators, unravelling a variety of behaviours ranging from localised movements made in relation to foraging opportunities (Sims et al 2006, Papastamatiou et al 2012) to larger-scale migrations (Bonfil et al 2005, Block et al 2011. In most cases, movements are driven by the availability of food resources (Zerbini et al 2006, Anderson et al 2011, species-specific physiologies (Pillans 2006) or the need to reproduce (Bonfil et al 2005, Skomal et al 2009).…”

“…Such technologies provided the first insights into the movement ecology of manta rays, highlighting diurnal visitations of reef manta rays Manta alfredi to particular inshore sites (Dewar et al 2008, Marshall 2008, movements between aggregation sites up to 500 km apart (Kashiwagi et al 2010, Couturier et al 2011) and seasonal migratory patterns in some regions (Anderson et al 2011, Couturier et al 2011. More recent telemetry studies have, for the first time, documented the movement patterns of both giant manta rays M. birostris and reef manta rays M. alfredi foraging in shallow habitats off the Yucatan Peninsula, Mexico, and in the Line Islands of the central Pacific, respectively (Graham et al 2012, Papastamatiou et al 2012. Such results have highlighted the importance of productivity blooms in inshore, coastal and coral reef ecosystems as key drivers for the spatial distributions and foraging habitats of manta rays (Graham et al 2012, Papastamatiou et al 2012.…”

Sei whale movements and behaviour in the North Atlantic inferred from satellite telemetry

“…Nevertheless, it is well established that ARS generally corresponds to foraging in marine predators (Mayo & Marx 1990, Fauchald 2009, Hamer et al 2009, Papastamatiou et al 2012. Another possibility is that ARS indicates resting or breeding behaviours (Bailey et al 2009).…”

Reliance of mobile species on sensitive habitats: a case study of manta rays (Manta alfredi) and lagoons

“…S6). This variability may stem from within habitat spatial heterogeneity in the factors that influence the quality and quantity of their planktonic prey (McCauley et al 2012a) as well as the divergent hydrological properties of these different lagoon basins which may affect the physical delivery of plankton (gardner et al 2011;Papastamatiou et al 2012).…”