Reynaldo Amorim Marinho

Phylogeographical Features of Octopus vulgaris and Octopus insularis in the Southeastern Atlantic Based on the Analysis of Mitochondrial Markers

ABSTRACT The genus Octopus occurs in tropical and temperate oceanic waters throughout the world, and currently includes 112 species, although the phylogenetic relationships among the different taxa are still poorly understood. The cosmopolitan Octopus vulgaris is one of the most widely analyzed cephalopods in genetic studies, primarily because of its ample range and the problems associated with the morphological identification of specimens, which indicate the possible existence of a species complex with a worldwide distribution. Two large-bodied octopus species—O. vulgaris and Octopus insularis—are found in the western South Atlantic. The limits of the geographical range of the O. insularis are still unclear. The current study is based on a phylogeographic analysis of the 2 species in the South Atlantic, with the objective of confirming their monophyletic status and the limits of their geographical distribution in this region. The analyses were based on the mitochondrial genes 16S rDNA and Cytochrome Oxidase subunit I (COI). The topologies generated for both genes confirmed the monophyletíc status of the 2 species. In the case of O. vulgaris, it was possible to confirm the monophyletic status of the specimens from this region relative to those of other areas around the world, although 3 distinct haplogroups were clearly differentiated, corresponding to the Americas, Europe and Africa, and Asia. The differentiation among these 3 groups may be determined by the limitations of the dispersal of paralarvae among continents. Further studies are needed to confirm the possible occurrence of distinct groups in the western South Atlantic, as well as the influence of oceanic currents on the phylogeographical distribution of O. vulgaris on the Brazilian coast.

Mollusks Found Inside Octopus (Mollusca, Cephalopoda) Pots in the State of Ceara, Northeast Brazil~!2008-09-15~!2008-12-01~!2009-01-06~!

The fishery of octopus in the State of Ceara is being carried out in the coast of Fortaleza, Redonda Beach (Icapui) and Itarema where 2 species can be found, Octopus insularis and O. vulgaris. The objective of this study was to investigate which prey species of mollusks were found inside the pots used in the octopus fishery. Unbaited octopus pots were set in Redonda Beach at 30 meters depth, in Fortaleza at 27 meters depth, and in Itarema at 30 meters depth. The species found inside the octopus pots that were consumed by Octopus vulgaris and O. insularis were mainly gastropods and bivalves. It was found 32 species of mollusks, being 17 of gastropods and 15 of bivalves. Redonda Beach presented the higher number of mollusk species in the octopus pots, with 85% of the total. The most preyed gastropod species was Aliger costatus (35.6%) and the most preyed bivalve species was Anadara notabilis (54.5%). Among the gastropods, 54% had a bore hole, the majority on the spire in the ventral side of the shell. This location is probably due to the presence of the columelar muscle, where it can inject the poison. Only 4.3 % of the bivalves found inside the octopus pots presented bore holes. Empty shells were censured in the field to indicate the magnitude of octopus predation relative to other sources of mortality and the percentage of empty shells with octopus drill holes ranged from 14% to 69%.