Reproductive season of the invasive cirripedia Balanus glandula in Puerto Madryn, Argentina: clues for understanding their success.

PACCOTTI, VANESA; PALACIO, ROMINA; BAZTERRICA, M CIELO; FERNANDO HIDALGO; CAITLIN CRAIN; BERTNESS, M

Mérida, Yucatán

Congreso; ESA.Ecology in an Era of Globalization: Challenges and Oppotunities for Environmental Scientists in the Americas; 2006

The Ecological Society of America

Marine species invasions are a widespread and important problem, however still little is known about what makes a species a good invader. Previous to the 1960 s the southern Atlantic coasts of Patagonia, Argentina, recently characterized as one of the most extreme intertidal environments worldwide due to dessication stress, were not significantly impacted by invasive species. In the mid-1970 s Balanus glandula, native to the Pacific coast of North America, invaded Mar del Plata (38 02 S, 57 32 W), Argentina, and has since spread as far south as Puerto Deseado (47 46 S; 65 54 W). Patagonian rocky shores are unique in that they harbor no native intertidal barnacle, meaning B. glandula invasion could potentially have large impacts on intertidal community dynamics. Because reproduction is a key process in driving the success of invasive species, here we examine the frequency and timing of reproduction in B. glandula in its invasive range and compare our findings to reports from its native range. To examine reproductive activity over time, fifty B. glandula individuals were randomly chosen in Punta Cuevas (Puerto Madryn, Chubut, Argentina) every fifteen days from July, 2004 to July, 2005 and reproductive stages characterized. Barnacles were analyzed under a magnifying glass (6x) and 4 reproductive stages were determined: (1) non-reproductive; (2) pre-reproductive: yellow mucus with traces of egg formation; (3) yellow eggs present and (4) brown eggs present in which some larval structures appear. We found that in Puerto Madryn, B. glandula is reproductively active most of the year and that barnacles with mature eggs can be found from April to December when the surface water temperature fluctuates between 11 and 15 C. B. glandula have two major spawning peaks, one in late August and the other in late October. In their native range, B glandula spawn twice between May-September, when water temperature is 9-14 C. Other authors have hypothesized that reproduction is a phenotypically plastic trait in barnacles that can be influenced by several variables. It is possible that in the south-western Atlantic, warmer water temperatures may enable B. glandula to lengthen its breeding season, favoring their success as colonizers and their rapid expansion along these shores.