Ecological Niche Modeling of Three Species of Stenella Dolphins in the Caribbean Basin, With Application to the Seaflower Biosphere Reserve

Dolphins of the genus Stenella occur in pelagic waters of both tropical and warm-temperate oceans. Three species, the Atlantic spotted dolphin (Stenella frontalis), the pantropical spotted dolphin (S. attenuata), and the spinner dolphin (S. longirostris) are abundant worldwide, but in the Caribbean Basin they have been poorly studied and information on their distribution patterns is scarce. Specifically, in Colombia’s remote Seaflower Biosphere Reserve (SFBR) S. attenuata has been reported occasionally, but S. frontalis and S. longirostris have never been recorded before. To address this information gap, an ecological niche modeling approach was used to determine the potential distribution patterns of these three dolphin species in the region. Records of these species for the Caribbean Basin were compiled, including both published and unpublished data. Environmental information, including bathymetry, bathymetric slope, distance to shore, sea surface temperature, sea surface salinity, and chlorophyll-a concentration was gathered from public databases (MARSPEC and Bio-ORACLE) in raster format. The maximum entropy algorithm (Maxent) for modeling species’ geographic distributions with presence-only data was used. After filtering the data, 210 records of S. attenuata, 204 of S. frontalis, and 80 of S. longirostris were used to run models. The best configuration for each model was chosen based on the ΔAICc criterion. For all three species, the final ecological niche models returned AUC test values higher than 0.8, indicating satisfactory model performance. The resulting potential distribution maps suggested that areas closest to continental shorelines of the Caribbean Basin and surrounding islands had the highest environmental suitability for all species (>70%). All models reported high environmental suitability for S. attenuata and S. longirostris in the SFBR, mainly in the southernmost part surrounding San Andrés and Providence Archipelago. Assessment of niche overlap from the predictions of species distributions using the similarity statistic and pairwise map overlap indicated that S. frontalis and S. longirostris had niches slightly more similar in comparison to S. attenuata. As this was a first effort to fill a gap in our understanding of the distribution of species in the genus Stenella in the Caribbean Basin, further studies are necessary using both niche modeling and biological/ecological approaches

Taxonomy based on science is necessary for global conservation

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Prevalence of external injuries in small cetaceans in Aruban waters, southern Caribbean.

Aruba, located close to the coasts of Colombia and Venezuela, is one of the most densely populated islands in the Caribbean and supports a wide range of marine-related socio-economic activities. However, little is known about the impacts of human activities on the marine environment. Injuries in marine mammals can be used to examine interactions with human activities and identify potential threats to the survival of populations. The prevalence of external injuries and tooth rake marks were examined in Atlantic spotted dolphin (Stenella frontalis) (n = 179), bottlenose dolphin (Tursiops truncatus) (n = 76) and false killer whale (Pseudorca crassidens) (n = 71) in Aruban waters using photo identification techniques. Eleven injury categories were defined and linked to either human-related activities or natural causes. All injury categories were observed. In total, 18.7% of all individuals had at least one injury. Almost half (41.7%) of the injuries could be attributed to human interactions, of which fishing gear was the most common cause (53.3%) followed by propeller hits (13.3%). Major disfigurements were observed in all three species and could be attributed to interactions with fishing gear. The results of this study indicate that fishing gear and propeller hits may pose threats to small and medium-sized cetaceans in Aruban waters. Thus, long-term monitoring of population trends is warranted. Shark-inflicted bite wounds were observed in Atlantic spotted dolphin and bottlenose dolphin. Bite wounds of cookie cutter sharks (Isistius sp.) were recorded in all three species, and include the first documented record of a cookie cutter shark bite in Atlantic spotted dolphin. This is one of the few studies which investigates the prevalence of injuries in cetaceans in the Caribbean. Further study is necessary to determine to which extent the injuries observed in Aruba affect the health and survival of local populations

Prevalence of injury types in Atlantic spotted dolphins, bottlenose dolphins and false killer whales in Aruban waters in 2010 en 2011.

<p>Numbers indicate individuals; numbers in parentheses indicate number of injuries.</p>a<p>Individuals can have more than one type of injury.</p

Injury categories.

<p>Illustrated are: (a) linear severed dorsal fin, (b) non-linear severed dorsal fin, (c) straight, deep cut, (d) opposing cuts, (e) parallel cuts, (f) partial collapse, (g) obtuse, short, cut-like indentation, (h) indentation, (i) round cut, (j) jagged, shark-inflicted bite wound, (k) cookie cutter shark bite wound.</p

The published complete mitochondrial genome of Eptesicus serotinus is a chimera of Vespertilio sinensis and Hypsugo alaschanicus (Mammalia: Chiroptera)

The mitogenome of Eptesicus serotinus (Serotine bat) was published in 2013 with GenBank accession number KF111725 and NCBI Reference Sequence number NC_022474. This sequence was placed with Vespertilio sinensis (Asian parti-colored bat) in a COI gene tree but with Hypsugo alashanicus (Alashanian pipistrelle) in a cytochrome b gene tree. Direct comparison of mitogenomes showed that 92.4% of this mitogenome is similar to Vespertilio sinensis, 5.9% to Hypsugo alaschanicus, and that 1.6% of the mitogenome could not be attributed to either species, or any other species. This mitogenome has been re-used in at least 17 phylogenies. Our findings suggest that mitogenomes are best verified with multiple gene trees, followed by direct comparison of sequences. We conclude that greater vigilance is warranted to ensure that problematic sequences do not enter the scientific record, and are not re-used in subsequent studies

The published complete mitochondrial genome of the milk shark (Rhizoprionodon acutus) is a misidentified Pacific spadenose shark (Scoliodon macrorhynchos) (Chondrichthyes: Carcharhiniformes)

The recently published mitogenome of milk shark Rhizoprionodon acutus (MN602076/NC_046016) was fully resolved in an unexpected phylogenetic position in the original mitogenome announcement, which rendered the genus Scoliodon paraphyletic. Here, we show that this mitogenome is actually that of a misidentified Pacific spadenose shark (Scoliodon macrorhynchos). The error is documented to avoid the perpetuation of erroneous sequence information in the literature

Study area and sighting locations.

<p>Sighting locations of Atlantic spotted dolphins (blue circles), bottlenose dolphins (red triangles) and false killer whales (black squares). Depth contours are in meters.</p

Tooth rake marks likely resulting from interspecific interactions.

<p>Illustrated are: (a) tooth rakes on the fluke of an Atlantic spotted dolphin, (b) tooth rakes on the tail stock of a bottlenose dolphin, (c) tooth rakes behind the dorsal fin of a false killer whale.</p

Injuries in Aruban cetaceans.

<p>Injuries include: (a) cut-like indentation and indentation injuries on the peduncle of an Atlantic spotted dolphin, (b) curvilinear incised scar, from left to right across its peduncle and extending to its left flank in an Atlantic spotted dolphin, (c) opposing cuts in the dorsal fin of an Atlantic spotted dolphin, (d) cookie cutter shark wound on the right flipper of an Atlantic spotted dolphin, (e) indentation marks on the dorsal fin of a bottlenose dolphin, (f) Scar of a healed shark-inflicted wound on the anterior peduncle of a bottlenose dolphin, (g) non-linear severed dorsal fin of a bottlenose dolphin, (h) oval shaped cuts in the trailing edge of a bottlenose dolphin, (i) parallel cuts behind the dorsal fin of a false killer whale, (j) linear severed dorsal fin with scar material (white) on either side of the missing fin of a false killer whale), (k) partial collapse of the dorsal fin of a false killer whale, (l) straight, deep vertical incisive scar on top of the dorsal fin of a false killer whale.</p