TY - JOUR
T1 - Population Abundance and Density Estimates for Costa Rica’s Endemic Sea Snake, Hydrophis platurus xanthos
AU - Bessesen, Brooke L.
AU - Oedekoven, Cornelia S.
AU - Galbreath, Gary J.
AU - González-Suárez, Manuela
N1 - Funding Information:
This research was supported by the University of Reading School of Biological Sciences with tremendous thanks to Len Thomas at the University of St. Andrews for instruction on distance sampling when animals are missed at zero distance and suggestions for how to address activity bias. Fieldwork was conducted under Costa Rican research permit N°: SINAC-ACOSA-DT-PI-R-010-2019 issued by the Ministry of Environment and Energy (MINAE) and National System of Conservation Areas (SINAC) with the institutional sponsorship of Osa Conservation. We sincerely thank our field team: observer Jorge Largaespada and boat captains Luis Nieto Vásquez and Marisol Jose Eladio. Thanks to Harvey Woodard and Susan Rogers for providing superb food and lodging at Saladero Eco Lodge. Additional support was provided by Mike Boston, Julio Ranalli, Guido Saborío Rodriguez, and Elizabeth Makings.
Funding Information:
This work was not supported by any funding organizations; open access publication fees were provided by the University of Reading.
Publisher Copyright:
Copyright © 2022 Bessesen, Oedekoven, Galbreath and González-Suárez.
PY - 2022/7/7
Y1 - 2022/7/7
N2 - Population abundance and density estimates provide key information for conservation assessment and prioritization of efforts and management. However, data are still largely unavailable for many taxa, including sea snakes, which appear to be facing global declines. Here, we present the first quantitative abundance and density estimates for the geographically isolated sea snake Hydrophis platurus xanthos endemic to the inner basin of Golfo Dulce, Costa Rica. Using systematic distance sampling methods, we obtained and analyzed 199 snake detections from 46 transect lines covering the entire known distribution (totaling nine days and 469 km of effort). Our modeling methods accounted for (i) the probability of detecting a snake given it was available to be detected (ii) the average availability of snakes at the water surface during a 24-hr cycle, and (iii) the by-hour variance in the taxon’s activity pattern. The best estimate of population abundance was 29781 individuals (95% CI=20104–44115) with an estimated density of 76 snakes/km2. Without historical abundance estimates or minimum viable population size, it is unknown whether this number represents a healthy population. However, with all individuals inhabiting a relatively small inlet increasingly exposed to anthropogenic impacts, the long-term persistence of H. p. xanthos may be threatened by ongoing impacts (boat propeller strikes, agricultural runoff, and climate change), as well as unforeseen events in the future.
AB - Population abundance and density estimates provide key information for conservation assessment and prioritization of efforts and management. However, data are still largely unavailable for many taxa, including sea snakes, which appear to be facing global declines. Here, we present the first quantitative abundance and density estimates for the geographically isolated sea snake Hydrophis platurus xanthos endemic to the inner basin of Golfo Dulce, Costa Rica. Using systematic distance sampling methods, we obtained and analyzed 199 snake detections from 46 transect lines covering the entire known distribution (totaling nine days and 469 km of effort). Our modeling methods accounted for (i) the probability of detecting a snake given it was available to be detected (ii) the average availability of snakes at the water surface during a 24-hr cycle, and (iii) the by-hour variance in the taxon’s activity pattern. The best estimate of population abundance was 29781 individuals (95% CI=20104–44115) with an estimated density of 76 snakes/km2. Without historical abundance estimates or minimum viable population size, it is unknown whether this number represents a healthy population. However, with all individuals inhabiting a relatively small inlet increasingly exposed to anthropogenic impacts, the long-term persistence of H. p. xanthos may be threatened by ongoing impacts (boat propeller strikes, agricultural runoff, and climate change), as well as unforeseen events in the future.
KW - Golfo Dulce yellow sea snake
KW - Hydrophis platurus xanthos
KW - abundance estimation models
KW - activity bias
KW - availability bias
KW - distance sampling
KW - line transect survey
KW - marine reptile
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U2 - 10.3389/fmars.2022.924966
DO - 10.3389/fmars.2022.924966
M3 - Article
AN - SCOPUS:85135157250
VL - 9
JO - Frontiers in Marine Science
JF - Frontiers in Marine Science
SN - 2296-7745
M1 - 924966
ER -