Megavertebrate communities from two contrasting ecosystems in the western tropical Atlantic

• Published in: Journal of Marine Systems
• Main Authors: Mannocci, Laura, Monestiez, Pascal, Bolaños-Jiménez, Jaime, Dorémus, Ghislain, Jeremie, Stephane, Laran, Sophie, Rinaldi, Renato, Van Canneyt, Olivier, Ridoux, Vincent
• Other Authors: Université de La Rochelle (ULR), Biostatistique et Processus Spatiaux (BioSP), Institut National de la Recherche Agronomique (INRA), Sociedad Ecol Venezolana Vida Marina, Partenaires INRAE, Soc Etud Protect & Amenagement Nat Martin, Assoc Evas Trop, The French Ministry in charge of the environment (Ministere de l'Ecologie, du Developpement durable, des Transports et du Logement, MEDDTL); Agency for marine protected areas (Agence des aires marines protegees, AAMP)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2013
• Subjects: Megavertebrates; Seabirds; Aerial survey; Antilles; Guiana; Productivity; Encounter rate; Community composition; Abundance; Density; GULF-OF-MEXICO; WHALE MEGAPTERA-NOVAEANGLIAE; BOTTLE-NOSED DOLPHINS; RED-FOOTED BOOBIES; HARBOR PORPOISE; AERIAL SURVEYS; NORTH-SEA; PRODUCTIVITY GRADIENT; SEABIRD COMMUNITY; Cetaceans; SOTALIA-GUIANENSIS CETACEA; [MATH]Mathematics [math]; [INFO]Computer Science [cs]; Megaptera novaeangliae
• Online Access: https://hal.inrae.fr/hal-02643870; https://doi.org/10.1016/j.jmarsys.2012.11.002

International audience Productivity was shown to structure megavertebrate communities, particularly in tropical oceans where they may be under selective pressure to maintain their foraging success in these low productivity environments. However, overall oligotrophic tropical oceans may encompass contrasting ecosystems. In the western tropical Atlantic, the Antilles and Guiana belong to two different biogeographic provinces and surface chlorophyll concentration is on average 10 times higher in Guiana. The aim of this study was to document megavertebrate communities in terms of encounter rates, species composition, abundance and spatial distribution and to compare them between these two contrasting regions. As part of an aerial census of cetaceans and other megavertebrates, line transect surveys were conducted across the French Antilles and Guiana. Both distance sampling and geostatistics were used to estimate abundance and geostatistics also provided maps of local density. Cetacean encounter rate was 3 times higher in Guiana (1.8 sightings/100 km) compared to the Antilles (0.6 sightings/100 km). Moreover, small delphinids strongly dominated in Guiana (representing 83% of the odontocete sightings) with a high abundance of bottlenose dolphins (Tursiops truncatus) (34,965 individuals, CV=0.28). Seabird encounter rate was similar in both regions (4.7 sightings/100 km in the Antilles and 3.6 sightings/100 km in Guiana). Charadriiformes, mainly represented by terns, were abundant in both regions whereas Pelecaniformes were only abundant in the Antilles and represented by frigatebirds, tropicbirds and boobies. Additionally, cetaceans and seabirds were mainly distributed close to the islands in the Antilles and were more widely distributed in Guiana. This study provided new information about megavertebrates which are poorly documented in these waters and highlighted differences in communities between these contrasting ecosystems. In particular, odontocete communities appeared to respond to productivity and may be ...