Abstract
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.
| Original language | English (US) |
|---|---|
| Article number | 924966 |
| Journal | Frontiers in Marine Science |
| Volume | 9 |
| DOIs | |
| State | Published - Jul 7 2022 |
Funding
This work was not supported by any funding organizations; open access publication fees were provided by the University of Reading. 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\u00B0: 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 V\u00E1squez 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 Sabor\u00EDo Rodriguez, and Elizabeth Makings.
Keywords
- Golfo Dulce yellow sea snake
- Hydrophis platurus xanthos
- abundance estimation models
- activity bias
- availability bias
- distance sampling
- line transect survey
- marine reptile
ASJC Scopus subject areas
- Oceanography
- Global and Planetary Change
- Aquatic Science
- Water Science and Technology
- Environmental Science (miscellaneous)
- Ocean Engineering
