Institute Biologia Marina y Pesquera Almirante Storni IBMPAS UNCo

San Antonio Oeste, Argentina

Institute Biologia Marina y Pesquera Almirante Storni IBMPAS UNCo

San Antonio Oeste, Argentina

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Storero L.P.,CONICET | Storero L.P.,Institute Biologia Marina y Pesquera Almirante Storni IBMPAS UNCo | Narvarte M.A.,Institute Biologia Marina y Pesquera Almirante Storni IBMPAS UNCo | Narvarte M.A.,CONICET | Gonzalez R.A.,Institute Biologia Marina y Pesquera Almirante Storni IBMPAS UNCo
Journal of the Marine Biological Association of the United Kingdom | Year: 2013

Population characteristics can be influenced by specific factors of the habitat and the natural variability of populations can confuse the effect related to protected environments. This study compares the demographic characteristics of Octopus tehuelchus in three coastal environments: two Marine Protected Areas (San Antonio Bay (SAB) and Islote Lobos (IL)) and a traditional fishing zone (El Fuerte (EF)). Weight–frequency distributions, sex-ratio and recruitment were monthly compared between the three intertidal zones. Octopus tehuelchus was smaller in IL, where fishing intensity is lower or null, and reached the largest sizes in the main fishing area of EF and within SAB (where there is no regulation and a mid–high fishing intensity). The sex proportion in SAB and EF was 1:1 all along the year. Although the proportion of mature females in IL was higher, the highest recruitment was observed in EF (the traditional fishing ground). These new data suggest that previous studies, which reported that Marine Protected Areas have positive effects for O. tehuelchus populations, can no longer be supported, and highlight the importance of understanding and quantifying the magnitude and range of natural variability in each environment when assessing the effectiveness of Marine Protected Areas. © 2012, Marine Biological Association of the United Kingdom. All rights reserved.


Hidalgo F.J.,CONICET | Firstater F.N.,CONICET | Firstater F.N.,Institute Biologia Marina y Pesquera Almirante Storni IBMPAS UNCo | Lomovasky B.J.,CONICET | Iribarne O.O.,CONICET
Journal of the Marine Biological Association of the United Kingdom | Year: 2013

Here we describe habitat use and the grazing effects of the sea urchin Tetrapygus niger and the gastropod Tegula atra in the low intertidal zone of a rocky shore in central Peru (Ancón bay: 11°46′S 77°12′W), where these two species were documented as coexisting with no evidence of habitat segregation between them. Gut content and isotopic analyses revealed differences between their diets: T. atra consumes mainly microalgae while Tetrapygus niger consumed also benthic macroalgae. Individual grazing effects were evaluated with inclusion/exclusion experiments. Tetrapygus niger prevented the colonization of the substrate by sessile organisms, including the dominant mussel Semimytilus algosus, while Tegula atra reduced the abundance of microalgae and green ephemeral macroalgae during early succession, but these effects were overwhelmed by the rapid increase in cover of S. algosus. We suggest that Tetrapygus niger plays a key role in this low intertidal community. Through directly limiting mussels to monopolize the substratum, T. niger can reduce the diversity of mussel associated species; conversely, through controlling primary space holders, T. niger can also benefit other grazers that live on bare substrate by maintaining a suitable area for feeding or living. © Marine Biological Association of the United Kingdom, 2013.

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