title: GRAZING ON GIANT KELP MICROSCOPIC PHASES AND THE RECRUITMENT SUCCESS OF ANNUAL POPULATIONS OF MACROCYSTIS PYRIFERA (LAMINARIALES, PHAEOPHYTA) IN SOUTHERN CHILE(1).
abstract: The giant kelp Macrocystis pyrifera (L.) C. Agardh is widely distributed in the Northern Hemisphere and Southern Hemisphere, yet it exhibits distinct population dynamics at local to regional spatial scales. Giant kelp populations are typically perennial with the potential for year-round reproduction and recruitment. In southern Chile, however, annual giant kelp populations exist and often persist entirely on secondary substrata (e.g., shells of the slipper limpet Crepipatella fecunda [Gastropoda, Calyptraeidae]) that can cover up to 90% of the rocky bottom. In these populations, the macroscopic sporophyte phase disappears annually during winter and early spring, leaving a 3-4 month period in which a persistent microscopic phase remains to support the subsequent year's recruitment. We tested the effects of a suite of grazers on the recruitment success of this critical microscopic phase at two sites in southern Chile. Field experiments indicated that the snail Tegula atra negatively impacted M. pyrifera sporophyte recruitment, but that recruitment was highest in the presence of sessile female limpets, C. fecunda. Conversely, small male C. fecunda (biofilm grazers) did not regulate kelp recruitment. Laboratory observations showed that C. fecunda males only grazed on microscopic kelp gametophytes and small (<250 μm) sporophytes, rejecting larger sporophytes, whereas T. atra grazed on all the kelp stages. Recruitment to the C. fecunda treatments far exceeded that to bare rock in the absence of grazers but was not due to the physical presence of C. fecunda shells. We concluded that the key to M. pyrifera recruitment success in southern Chile is its capacity to colonize secondary substrates provided by the slipper limpet C. fecunda.
authors.affiliation: Centro i-mar, Universidad de Los Lagos, Camino Chinquihue km 6, Puerto Montt, ChileMoss Landing Marine Laboratories, 8272 Moss Landing Road, Moss Landing, California 95039, USACentro i-mar, Universidad de Los Lagos, Camino Chinquihue km 6, Puerto Montt, Chile.
authors.forename: Luis A
authors.initials: LA
authors.lastname: Henríquez
authors.affiliation: Centro i-mar, Universidad de Los Lagos, Camino Chinquihue km 6, Puerto Montt, ChileMoss Landing Marine Laboratories, 8272 Moss Landing Road, Moss Landing, California 95039, USACentro i-mar, Universidad de Los Lagos, Camino Chinquihue km 6, Puerto Montt, Chile.
authors.forename: Alejandro H
authors.initials: AH
authors.lastname: Buschmann
authors.affiliation: Centro i-mar, Universidad de Los Lagos, Camino Chinquihue km 6, Puerto Montt, ChileMoss Landing Marine Laboratories, 8272 Moss Landing Road, Moss Landing, California 95039, USACentro i-mar, Universidad de Los Lagos, Camino Chinquihue km 6, Puerto Montt, Chile.
authors.forename: Miguel A
authors.initials: MA
authors.lastname: Maldonado
authors.affiliation: Centro i-mar, Universidad de Los Lagos, Camino Chinquihue km 6, Puerto Montt, ChileMoss Landing Marine Laboratories, 8272 Moss Landing Road, Moss Landing, California 95039, USACentro i-mar, Universidad de Los Lagos, Camino Chinquihue km 6, Puerto Montt, Chile.
authors.forename: Michael H
authors.initials: MH
authors.lastname: Graham
authors.affiliation: Centro i-mar, Universidad de Los Lagos, Camino Chinquihue km 6, Puerto Montt, ChileMoss Landing Marine Laboratories, 8272 Moss Landing Road, Moss Landing, California 95039, USACentro i-mar, Universidad de Los Lagos, Camino Chinquihue km 6, Puerto Montt, Chile.
authors.forename: María Carmen
authors.initials: MC
authors.lastname: Hernández-González
authors.affiliation: Centro i-mar, Universidad de Los Lagos, Camino Chinquihue km 6, Puerto Montt, ChileMoss Landing Marine Laboratories, 8272 Moss Landing Road, Moss Landing, California 95039, USACentro i-mar, Universidad de Los Lagos, Camino Chinquihue km 6, Puerto Montt, Chile.
authors.forename: Sandra V
authors.initials: SV
authors.lastname: Pereda
authors.affiliation: Centro i-mar, Universidad de Los Lagos, Camino Chinquihue km 6, Puerto Montt, ChileMoss Landing Marine Laboratories, 8272 Moss Landing Road, Moss Landing, California 95039, USACentro i-mar, Universidad de Los Lagos, Camino Chinquihue km 6, Puerto Montt, Chile.
authors.forename: Marcelo I
authors.initials: MI
authors.lastname: Bobadilla
keywords: annual population dynamics; grazing; kelp systems; microscopic stages; plant-herbivore interaction; recruitment