Scale-dependent effects of habitat on movements and path structure of reef sharks at a predator-dominated atoll

Yannis Papastamatiou, Christopher G. Lowe, Jennifer E. Caselle, Alan M. Friedlander

Research output: Contribution to journalArticlepeer-review

134 Citations (Scopus)

Abstract

The effects of habitat on the ecology, movements, and foraging strategies of marine apex predators are largely unknown. We used acoustic telemetry to quantify the movement patterns of blacktip reef sharks (Carcharhinus melanopterus) at Palmyra Atoll National Wildlife Refuge, in the Pacific Ocean. Sharks had relatively small home ranges over a timescale of days to weeks (0.55 +/- 0.24 km(2)) and showed strong site fidelity to sand-flat ledges within the west lagoon over a three-year period. Sharks showed evidence of diel and tidal movements, and they utilized certain regions of the west lagoon disproportionately. There were ontogenetic shifts in habitat selection, with smaller sharks showing greater selection for sand-flat habitats, and pups (total length 35-61 cm) utilizing very shallow waters on sand-flats, potentially as nursery areas. Adult sharks selected ledge habitats and had lower rates of movement when over sand-flats and ledges than they did over lagoon waters. Fractal analysis of movements showed that over periods of days, sharks used patches that were 3-17% of the scale of their home range. Repeat horizontal movements along ledge habitats consisted of relatively straight movements, which theoretical models consider the most efficient search strategy when forage patches may be spatially and temporally unpredictable. Although sharks moved using a direct walk while in patches, they appeared to move randomly between patches. Microhabitat quantity and quality had large effects on blacktip reef shark movements, which have consequences for the life-history characteristics of the species and potentially the spatial distribution of behaviorally mediated effects on lower trophic levels throughout the Palmyra ecosystem.

Original languageEnglish
Pages (from-to)996-1008
Number of pages13
JournalEcology
Volume90
Issue number4
DOIs
Publication statusPublished - Apr 2009

Keywords

  • acoustic telemetry
  • blacktip reef sharks
  • foraging behavior
  • fractal analysis
  • habitat utilization
  • nursery areas
  • Palmyra Atoll
  • predator-dominated ecosystems
  • JUVENILE LEMON SHARKS
  • NORTHERN LINE ISLANDS
  • NEGAPRION-BREVIROSTRIS
  • CARCHARHINUS-MELANOPTERUS
  • FRACTAL ANALYSIS
  • HOME-RANGE
  • PATTERNS
  • BEHAVIOR
  • GROUNDS
  • ECOLOGY

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