[MARMAM] Sotalia guianensis in the southern Gulf of Venezuela

Hector Barrios-Garrido PhD hbarriosg at gmail.com
Mon Oct 21 17:01:12 PDT 2019


Dear MARMAM readers:

We are happy to share #GeneralEcologyLab_LUZ
<https://www.facebook.com/hashtag/generalecologylab_luz?source=feed_text&epa=HASHTAG>
latest
article entitled:
Guiana Dolphin (*Sotalia guianensis*) in the southern Gulf of Venezuela:
Seasonal distribution, group size, and habitat use.
Free to download (for 50 days):
https://authors.elsevier.com/a/1Zx9v8MvAtjw4K

More than happy to answer questions, comments, and collaboration
opportunities!

The authors


Abstract:

Small cetaceans, such as the Guiana dolphin (Sotalia guianensis), do not
migrate long distances to forage but use rather small areas subject to food
source variations. Information on their distribution, behaviour, habitat
use, and estimated population density play an important role in the
identification of critical areas and regulating human activities within.
Here we examine the seasonal variations, group size, and distribution of
Guiana dolphin in the southern Gulf of Venezuela, to identify their
critical habitats and thus aid mitigation planning. We used boat-based
surveys with a follow-group protocol where observers monitor groups of
animals for 30 min, from a distance of 20 to 30 m, gathering the following
data: date, time observed, GPS position, estimated number of individuals,
presence of calves, behavioural observations (when possible); and
environmental parameters (sea-surface temperature, water transparency,
salinity, sea state [Beaufort], and cloud cover). We found that Guiana
dolphins did not use the studied area (6.33 Km2) homogeneously but rather
aggregated in north of Zapara Island’s retaining wall. The highest density
of dolphins was between 301 and 573 individuals within 4.22 Km2
approximately off north of Zapara Island, and the lowest (1 - 150
individuals) at the entrance of the main navigation channel. The group size
was considerably larger in the wet season (mean ± SD = 6.4 ± 1.9
individuals, range = 1 to 80) than the dry season (2.2 ± 2.7 individuals,
range = 1 to 27). The number of sightings differed among seasons (dry/wet),
there were more sightings in the wet season (1.3414 ± 0.4389 groups, range
= 1 to 5) than dry season (1.1233 ± 0.7418 groups, range = 1 to 5). Our
data suggest this population might be highly adapted to local conditions
and prey movements, and use the areas intensely year around, particularly
during the wet season.

Citation:
Espinoza Rodríguez, N., De Turris-Morales, K., Shimada, T., &
Barrios-Garrido, H. 2019. Guiana Dolphin (Sotalia guianensis) in the
southern Gulf of Venezuela: Seasonal distribution, group size, and habitat
use: Guiana Dolphin in the southern Gulf of Venezuela. Regional Studies in
Marine Science, 1-8. doi: https://doi.org/10.1016/j.rsma.2019.100874
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