Occurrence and use of an estuarine habitat by giant manta ray Manta birostris

Abstract

Based on the knowledge of local artisanal fishermen and on direct observations, this study presents evidence that the giant manta ray Manta birostris uses the Paranaguá estuarine complex in south Brazil, south-western Atlantic Ocean, in a predictable seasonal pattern. Behavioural observations suggest that the estuary can act as a nursery ground for M. birostris during the summer.

Interactions between Manta birostris and Sotalia guianensis in a World Heritage listed Brazilian estuary

“…Breaching is quite common among Manta spp. and has been attributed to mating displays, parturition, removing attached remoras, playing and communicating (Rayner, ; Medeiros et al ., ). Based on the observations here, sequential breaches by M. birostris above schools would disrupt and disorientate individuals thereby increasing the chances of predation, although it remains uncertain if teleosts are a dietary component (Burgess et al ., ).…”

“…This communication reaffirms that M. birostris use the PEC on a predictable basis for key life‐history events that remain somewhat cryptic, during which they maintain their characteristic breaching behaviour possibly to facilitate food acquisition (Medeiros et al ., ). Sotalia guianensis has clearly learned to recognize such breaches as a signal to the presence of teleosts (probably Clupeidae and Engraulidae) and apparently to improve their predation success rate.…”

“…300 m off the beach, when a solitary M. birostris ( c . 4 m disc width; W D ) breached once or twice adjacent to the school and landed on its dorsal surface directly over the school [see Medeiros et al ., for a description of breaching]. Immediately following the final breach, between six and 20 S. guianensis (involving different groups, identified by dorsal‐fin marks) surfaced at the school and executed characteristic foraging behaviours, including deep diving, crossed fishing activities and circle formation (Monteiro‐Filho, ; Tardin et al ., ).…”

“…Despite its global distribution and status as the world's largest batoid, the ecology and biology of M. birostris remain poorly understood and are based on opportunistic observations (Luiz et al, 2009;Medeiros et al, 2015;Burgess et al, 2016). Their diet is thought to comprise predominantly zooplankton (Burgess et al, 2016); differences in the relative spatio-temporal abundances of which probably affect M. birostris distributions (Luiz et al, 2009).…”

“…Their diet is thought to comprise predominantly zooplankton (Burgess et al, 2016); differences in the relative spatio-temporal abundances of which probably affect M. birostris distributions (Luiz et al, 2009). Specifically, the wet summers (typical rainfall >2500 mm year −1 ) in southern Brazil produce high levels of suspended organic material and nutrients in estuaries which support zooplankton and their predators (Possatto et al, 2016) and might explain why M. birostris is most frequently observed in the PEC from January to April (Medeiros et al, 2015).…”