El rol del cirripedio introducido Balanus glandula como ingeniero ecosistémico en intermareales de Patagonia, Argentina.
The acorn barnacle Balanus glandula has been accidentally introduced in Argentina in early 1970s. The specie, native of the Pacific coast of North America, has reached an alarming expansion of 17 degrees to the south, finding from San Clemente del Tuyú to Río Grande. Recently, it has been reported the specie successfully colonising soft-bottom salt marshes; a very surprising fact given that B. glandula is typical a rocky shore species. This barnacle is considered an autogenic engineer species or habitat-forming, capable of change the physical structure, complexity, and heterogeneity of the environment through their own structure. The main objective of this thesis is to evaluate the role of the introduced barnacle B. glandula as an engineer species in intertidal environments of Patagonia, Argentina. Ecosystem engineer is a relatively recent concept which has generated a great interest in the scientific community in the last two decades, developing a vast amount of ecology studies. This concept provides the theoretical frame on which the thesis is based, thus in the first chapter a literature review is performed as an introduction, highlighting the importance of marine introduced species as ecosystem engineer and particularly its extent to Argentinean introduced species. Then, in the second chapter the existences of differences in the community composition associated to the presence of B. glandula are evaluated. In the third chapter, the effects of the physical structure of the barnacles on the benthic fauna are experimentally evaluated. Lastly, in the fourth chapter the substrata most successfully colonized by B. glandula in Patagonian salt marshes are identified and characterized through descriptive and manipulative experiments. The information compiled during the literature review emphasized the importance of the potential effects that introduced and ecosystem engineer species could generate. In Chapter 2, barnacles grouped together forming three-dimensional structures of large sizes are observed. In these structures, named here aggregates, micro-habitats that can be used by the rest of the macrofauna to avoid thermal stress and predation are generated. Results of this chapter show that B. glandula aggregates are essential in determining the distribution and abundance of the invertebrate species found in Patagonian salt marshes. In Chapter 3, results were coincident with the ones from Chapter 2, suggesting that the physical structure, rather than the biological or ecological properties, would be the responsible for the effects caused by B. glandula on the benthic community. Moreover, barnacles were observed recruited on the artificial-barnacles structures utilized in Chapter 3; these barnacles were bigger than the ones observed in natural substrata. Finally, field surveys and manipulative experiments of Chapter 4 have shown that acorn barnacles recruit on a great number of substrata, including mobile ones. Among this kind of substrata, there were barnacles recruited on the endemic crab Neohelice granulata. These barnacles were found in vital zones of the crab which could affect the normal behaviour of the species. When differences in barnacle’s recruitment among different substrata were experimentally evaluated, the halophyte Limonium brasiliense showed the highest density of barnacles and the largest individuals. Nevertheless, the results of this chapter suggest that the presence of B. glandula in the salt marshes do not depend on the presence/availability of any particular substratum. Together, the results obtained in the different chapters of this thesis, provide new information and stand out the importance of B. glandula as an engineer species in structuring the invertebrate community of Patagonian salt marshes. As well, they show the versatility of this rocky shore species to exploit a wide variety of substrata to persist in these soft- bottom environments.
| Main Author: | |
|---|---|
| Format: | Thesis/Dissertation biblioteca |
| Language: | Spanish / Castilian |
| Published: |
Universidad Naconal del Comahue. Centro Regional Universitario Bariloche
2013
|
| Subjects: | Especies introducidas, Ambiente intermareal, Marismas, Composición de la comunidad, Ambiente bentónico, Ecosistemas, Revisión bibliográfica, Balanus glandula, ASFA15::I::Introduced species, ASFA15::I::Intertidal environment, ASFA15::S::Salt marshes, ASFA15::C::Community composition, ASFA15::B::Benthic environment, ASFA15::E::Ecosystems, ASFA15::L::Literature reviews, |
| Online Access: | http://hdl.handle.net/1834/6805 |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|