Coral Reefs

, Volume 32, Issue 4, pp 1123–1134

Topography and biological noise determine acoustic detectability on coral reefs

Report

DOI: 10.1007/s00338-013-1069-2

Cite this article as:
Cagua, E.F., Berumen, M.L. & Tyler, E.H.M. Coral Reefs (2013) 32: 1123. doi:10.1007/s00338-013-1069-2

Abstract

Acoustic telemetry is an increasingly common tool for studying the movement patterns, behavior and site fidelity of marine organisms, but to accurately interpret acoustic data, the variability, periodicity and range of detectability between acoustic tags and receivers must be understood. The relative and interactive effects of topography with biological and environmental noise have not been quantified on coral reefs. We conduct two long-term range tests (1- and 4-month duration) on two different reef types in the central Red Sea to determine the relative effect of distance, depth, topography, time of day, wind, lunar phase, sea surface temperature and thermocline on detection probability. Detectability, as expected, declines with increasing distance between tags and receivers, and we find average detection ranges of 530 and 120 m, using V16 and V13 tags, respectively, but the topography of the reef can significantly modify this relationship, reducing the range by ~70 %, even when tags and receivers are in line-of-sight. Analyses that assume a relationship between distance and detections must therefore be used with care. Nighttime detection range was consistently reduced in both locations, and detections varied by lunar phase in the 4-month test, suggesting a strong influence of biological noise (reducing detection probability up to 30 %), notably more influential than other environmental noises, including wind-driven noise, which is normally considered important in open-water environments. Analysis of detections should be corrected in consideration of the diel patterns we find, and range tests or sentinel tags should be used for more than 1 month to quantify potential changes due to lunar phase. Some studies assume that the most usual factor limiting detection range is weather-related noise; this cannot be extrapolated to coral reefs.

Keywords

Passive monitoring Acoustic transmitters Detection efficiency Saudi Arabia 

Supplementary material

338_2013_1069_MOESM1_ESM.eps (586 kb)
Fig. S1 Periodogram Power Spectral Density (PSD) estimate of the sum of detections from all receivers in a Malathu and b Shib Habil. PSD was computed using a Fast Fourier Transform. In both cases it’s possible to identify diel cycle. The periodogram in Shib Habil suggests a potential high variability in periods of about a week and 3 months (EPS 585 kb)

Copyright information

© Springer-Verlag Berlin Heidelberg 2013

Authors and Affiliations

  • E. F. Cagua
    • 1
  • M. L. Berumen
    • 1
    • 2
  • E. H. M. Tyler
    • 1
    • 3
  1. 1.Red Sea Research CenterKing Abdullah University of Science and TechnologyThuwalSaudi Arabia
  2. 2.Biology DepartmentWoods Hole Oceanographic InstitutionWoods HoleUSA
  3. 3.Zoology DepartmentUniversity of CambridgeCambridgeUK

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