Phylogeny of the Sepia officinalis species complex in the eastern Atlantic extends the known distribution of Sepia vermiculata across the Benguela upwelling region
- Authors: Healey, Amy J E , McKeown, Niall J , Potts, Warren M , de Beer, Chénelle L , Sauer, Warwick H H , Shaw, Paul W
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/125631 , vital:35802 , https://doi.10.2989/1814232X.2017.1371076
- Description: Accurate species identification and biogeographic characterisation are fundamental for appropriate management of expanding cephalopod fisheries. This study addresses this topic within the common cuttlefish Sepia officinalis species complex (S. officinalis, S. hierredda and S. vermiculata), with an emphasis on occurrence in African waters. Tissue samples from the currently presumed distributions of S. vermiculata and S. hierredda (from South Africa and Ghana/Angola, respectively) were sequenced for the cytochrome c oxidase subunit I (COI) and the cytochrome b (cytb) genes of the mitochondrial genome and then compared to existing S. officinalis sequences. Three highly divergent and reciprocally monophyletic clades, corresponding to S. officinalis, S. hierredda and S. vermiculata, were resolved, representing the first molecular confirmation of the distinct species status of S. hierredda and S. vermiculata. The sequences also revealed that, contrary to expectations based on presently published information, all samples from southern Angola were S. vermiculata. These results indicate that the range of S. vermiculata extends beyond the currently described northern limit and that S. hierredda and S. vermiculata may be indiscriminately harvested in Angolan waters. Finer-scale patterns within S. vermiculata phylogeography also indicate that the Benguela Current System and/or other environmental factors serve to isolate northern and southern stocks.
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- Date Issued: 2017
Behavioural observations of the common octopus Octopus vulgaris in Baía dos Tigres, southern Angola
- Authors: de Beer, Chénelle L , Potts, Warren M
- Date: 2013
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/123233 , vital:35419 , https://doi.org/10.2989/1814232X.2013.847496
- Description: The common octopus Octopus vulgaris (Cuvier 1797) is a shallow-water cephalopod species that inhabits coastal rocky areas or reefs. It is the most studied and widely distributed species in its genus. This species has a short lifespan and a rapid growth rate of over 5% of body weight per day (García and Valverde 2006, Ibáñez and Keyl 2010). It is semelparous, with females laying large strings of eggs that they attach to the substrata in their dens (Hernández- García et al. 2002). There is a paucity of information on the preferred habitat and behaviour of O. vulgaris in its natural environment (Anderson 1997, Meisel et al. 2006). The species has been classified as highly mobile, yet resident individuals may exhibit high levels of territoriality. Its mobility allows it to move efficiently between a wide range of suitable habitats (Katsanevakis and Verriopoulos 2004). Octopus make use of both tactile and visual senses to forage, feed and seek suitable shelter (Forsythe and Hanlon 1997, Carvalho and Sousa Reis 2003, Rodríguez-Rúa et al. 2005). They are active feeders that seek out prey such as crustaceans, sessile molluscs and small fish (Forsythe and Hanlon 1997, Boyle and Rodhouse 2005), as well as their smaller conspecifics (Ibáñez and Keyl 2010). The majority of behavioural ecology studies on octopus have been on captive individuals. However, the activity patterns (Mather 1988), foraging strategies and aspects of the movement behaviour (Mather and O’Dor 1991) of juvenile O. vulgaris in the wild were described for an exploited population in Bermuda. Because intertidal octopus stocks are exploited by recreational, subsistence and artisanal fisheries (e.g. Oosthuizen and Smale 2003, Sauer et al. 2011), there are few opportunities to study the behavioural ecology of unexploited populations. An opportunity arose to study various behavioural patterns in an unexploited population in Baía dos Tigres, a large (~200 km2) coastal embayment situated on an isolated stretch of the southern Angolan coast (Figure 1). This study provides information on the population size structure, aspects of the movement behaviour, activity patterns and foraging strategies of O. vulgaris in this largely unstudied coastal embayment.
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- Date Issued: 2013