Publications des scientifiques de l'IRD

Hagihara R., Jones R. E., Sobtzick S., Cleguer C., Garrigue Claire, Marsh H. (2018). Compensating for geographic variation in detection probability with water depth improves abundance estimates of coastal marine megafauna. PLoS One, 13 (1), p. e0191476 [15 p.]. ISSN 1932-6203.

Titre du document
Compensating for geographic variation in detection probability with water depth improves abundance estimates of coastal marine megafauna
Année de publication
2018
Type de document
Article référencé dans le Web of Science WOS:000423416600056
Auteurs
Hagihara R., Jones R. E., Sobtzick S., Cleguer C., Garrigue Claire, Marsh H.
Source
PLoS One, 2018, 13 (1), p. e0191476 [15 p.] ISSN 1932-6203
The probability of an aquatic animal being available for detection is typically < 1. Accounting for covariates that reduce the probability of detection is important for obtaining robust estimates of the population abundance and determining its status and trends. The dugong (Dugong dugon) is a bottom-feeding marine mammal and a seagrass community specialist. We hypothesized that the probability of a dugong being available for detection is dependent on water depth and that dugongs spend more time underwater in deep-water seagrass habitats than in shallow-water seagrass habitats. We tested this hypothesis by quantifying the depth use of 28 wild dugongs fitted with GPS satellite transmitters and time-depth recorders (TDRs) at three sites with distinct seagrass depth distributions: 1) open waters supporting extensive seagrass meadows to 40 m deep (Torres Strait, 6 dugongs, 2015); 2) a protected bay (average water depth 6.8 m) with extensive shallow seagrass beds (Moreton Bay, 13 dugongs, 2011 and 2012); and 3) a mixture of lagoon, coral and seagrass habitats to 60 m deep (New Caledonia, 9 dugongs, 2013). The fitted instruments were used to measure the times the dugongs spent in the experimentally determined detection zones under various environmental conditions. The estimated probability of detection was applied to aerial survey data previously collected at each location. In general, dugongs were least available for detection in Torres Strait, and the population estimates increased 6 +/- 7 fold using depth-specific availability correction factors compared with earlier estimates that assumed homogeneous detection probability across water depth and location. Detection probabilities were higher in Moreton Bay and New Caledonia than Torres Strait because the water transparency in these two locations was much greater than in Torres Strait and the effect of correcting for depth-specific detection probability much less. The methodology has application to visual survey of coastal mega-fauna including surveys using Unmanned Aerial Vehicles.
Plan de classement
Limnologie biologique / Océanographie biologique [034] ; Ecologie, systèmes aquatiques [036] ; Télédétection [126]
Description Géographique
AUSTRALIE ; NOUVELLE CALEDONIE ; OCEAN INDIEN ; PACIFIQUE ; TORRES DETROIT ; MORETON BAIE
Localisation
Fonds IRD [F B010072437]
Identifiant IRD
fdi:010072437
Contact