Ramírez-León M Rafael, García-Aguilar María C, Romo-Curiel Alfonsina E, Ramírez-Mendoza Zurisaday, Fajardo-Yamamoto Arturo, Sosa-Nishizaki Oscar
Posgrado en Ecología Marina, Centro de Investigación Científica y de Educación Superior de Ensenada, Baja California, Ensenada, Baja California, Mexico.
Departamento de Oceanografía Biológica, Centro de Investigación Científica y de Educación Superior de Ensenada, Baja California, Ensenada, Baja California, Mexico.
PeerJ. 2021 Mar 17;9:e10834. doi: 10.7717/peerj.10834. eCollection 2021.
The Gulf of Mexico (GOM) is a semi-enclosed sea where the waters of the United States, Mexico and Cuba converge. Al least 21 species of cetaceans inhabit it. The only mysticete (baleen whale) is found in the northeast (U.S. waters). The distribution of the 20 species of odontocetes (toothed cetaceans) is well understood in U.S. waters, but practically unknown in Mexican and Cuban waters. In this study we used sighting data from several odontocete species to construct habitat suitability maps in order to identify geographical regions suitable for high diversity throughout the GOM.
Historical datasets of georeferenced sightings from across the GOM were used to implement the maximum entropy algorithm (MaxEnt) to model the habitat suitability of each species. Five environmental predictors were used, selected for their influence over the occurrence of cetaceans: two oceanographic predictors (sea surface temperature and chlorophyll- concentration), and three bathymetric predictors (depth, slope, and distance to 200-m isobath). A spatial approach based on the habitat suitability maps was used to identify the suitable regions.
Only 12 species were modeled, which were the ones with the minimum sample size required. The models performed well, showing good discriminatory power and slight overfitting. Overall, depth, minimum sea surface temperature, and bottom slope were the most contributing predictor in the models. High suitability areas of 10 species were located on the continental slope, and four suitable regions were identified: (1) the Mississippi Canyon and the Louisiana-Texas slope in the northern GOM, (2) the west Florida slope in the east-northeastern GOM, (3) the Rio Grande slope in the west-northwestern GOM, and (4) the Tamaulipas-Veracruz slope in the west-southwestern GOM.
We were able to detect four geographic regions in the GOM where a high diversity of odontocetes is expected, all located on the continental slope. Although the methodology to identify them (spatial overlap) is a very conservative approach, it is useful for conservation and management purposes. The paucity of data did not allow all species to be modeled, which highlights the importance of establishing transboundary monitoring programs.
墨西哥湾是一个半封闭海域，美国、墨西哥和古巴的海域在此交汇。至少有21种鲸目动物栖息于此。唯一的须鲸类动物（须鲸）分布在东北部（美国海域）。20种齿鲸类动物（有齿鲸）在美国海域的分布情况已为人熟知，但在墨西哥和古巴海域几乎无人知晓。在本研究中，我们利用几种齿鲸类动物的目击数据构建栖息地适宜性地图，以确定整个墨西哥湾适合高生物多样性的地理区域。
利用来自整个墨西哥湾的地理参考目击历史数据集，实施最大熵算法（MaxEnt）来模拟每个物种的栖息地适宜性。使用了五个环境预测因子，因其对鲸目动物出现的影响而被选中：两个海洋学预测因子（海面温度和叶绿素浓度），以及三个测深预测因子（深度、坡度和到200米等深线的距离）。基于栖息地适宜性地图的空间方法被用于识别适宜区域。
仅对12个物种进行了建模，这些物种是满足所需最小样本量的物种。模型表现良好，具有良好的判别能力且略有过拟合。总体而言，深度、最低海面温度和海底坡度是模型中贡献最大的预测因子。10个物种的高适宜性区域位于大陆坡上，并确定了四个适宜区域：（1）墨西哥湾北部的密西西比峡谷和路易斯安那 - 得克萨斯斜坡，（2）墨西哥湾东北偏东的西佛罗里达斜坡，（3）墨西哥湾西北偏西的里奥格兰德斜坡，以及（4）墨西哥湾西南偏西的塔毛利帕斯 - 韦拉克鲁斯斜坡。
我们能够在墨西哥湾检测到四个预计齿鲸多样性较高的地理区域，均位于大陆坡上。尽管识别它们的方法（空间重叠）是一种非常保守的方法，但它对保护和管理目的很有用。数据的匮乏使得无法对所有物种进行建模，这凸显了建立跨界监测计划的重要性。
