4 CDNICYT COMI5IÓ NACIONAL DE INVE5TIGAOÓN CIENTÍFICA Y TECNOLÓGICA GOBIERNO DE CHILE y -. -_ COM1S1O NACIONAL DL INVESIJUAL ION CIENCIA Y 1 LCNOLOUI\ VERSION OFICIAL FECHA: 16/3/2009 PROYECTO REGULAR N°1060127 INVESTIGADOR RESPONSABLE: THIEL MARTIN FONDO NACIONAL DE DESARROLLO CIENTIFICO Y TECNOLOGICO (FONDECYT) Bernarda Morín 551, Providencia - casilla 297- y, Santiago 21 Telefono: 435 43 50 FAX 365 4435 Email: informes.fondecyt@ con¡ cyt.cI INFORME FINAL PROYECTO FONDECYT REGULAR RELACIONADO SR. MARTIN THI N° PROYECTO: 1060127 DURACIÓN: 3 años AÑO ETAPA: 2008 TÍTULO PROYECTO: RAFTING DISPERSAL ON MACROALGAE DEPENDS QN FLOATINO TIME-FACTORS AFFECTING THE SURVI VAL OF FLOATING KELP AFTER DETACHMENT. DISCIPLINA PRINCIPAL: BIOLOGIA MARINA GRUPO DE ESTUDIO: BIOLOGIA 1 INVESTIGADOR(A) RESPONSABLE: THIEL MARTIN DIRECCIÓN: Larrondo 1281, Casilla 117 RELACIONAD COMUNA: Coquimbo CIUDAD: Coquimbo SR. IVAN GOrv REGIÓN: IV REGION FONO: 5 1-209939 EMAIL: [email protected] INFORME OBJETIVOS Cumplimiento de los Objetivos planteados en el Proyecto. Recuerde que los objetivos del proyecto no se refieren a listar actividades desarrolladas sino a los obietivos desarrollados N° OBJETIVOS CUMPLIMIENTO FUNDAMENTO 1 Examine the effect of water temperature and TOTAL grazing on fioatíng algae 2 Examine the effect of nutrients and temperature TOTAL on fioating algae 3 Examine the effect of PAR/UV-radiation and TOTAL - grazing 00 floating algae 4 Examine the effect of water temperature and TOTAL UV-radiation, on survival, growth and vitality of - floating Macrocystis spp. 5 Examine the effect of UV-radiation, on survival TOTAL growth and physiological performance of fioating Macrocystis spp. in their natural cnvironment. Otro(s) aspecto(s) que Ud. considere importante(s) en la evaluación del cumplimiento de objetivos planteados en la propuesta original o en las modificaciones autorizadas por los Consejos. In the original project, within the general objective to identif' the factors that influence survival and vitality of floating kelp, it was planned to do a long-term experiment over a time period of>2 months. However, experimental results from the tirst two years suggested that such an experiment will not produce new insights. Therefore, the objective 4 was modified to test thc combined effects of temperature and UVR, which was officially accepted by FONDECYT/CONICYT. Actually it was planned in the original project, to conduct objectivc 5 with the amphipod Peramphithoe femorata. However, during the summer 2008/09 this grazer was not very abundant in the kelp forests of the region of Coquimbo. We surveyed diftrent kelp forcsts nearby Coquimbo and tried to col lect them but we were unable to collect the large quantity of amphipods necessary for thc two cxperiments. For that reason and due to the fact that results from previous studies (objective 3) did not show any interactions between grazing and UVR, we finaily decided to concentrate our outdoor-laboratory and uield experiments only on the factor Uy. RESULTADOS OBTENIDOS: Please find attached in Appendix 1 figures" and in Appendix II "references' OBJECTIVE 1 (Iaboratory : Examine the effect of water temperature and grazinc on fIoatinc algae. OBJIa - Materials & Methods: In order to determine the effect of the factor temperature and herbivory on survival and vitality of floating Macrocystis spp. along the Chilean coast, an outdoor-tank experiment was conducted in Iquique (Universidad Arturo Prat), Coquimbo (Universidad Católica del Norte) and Calfuco (Laboratorio Costero de los Recursos Acuaticos, Universidad Austral de Chile) in austral summer 2007. Detached floating sporophytes were cultured at three different water temperatures and with or without the common amphipod grazer Peramphithoe femorata. Each treatment combination was replicated four times. At each location, we maintained floating algae at ambient temperature (incoming seawater), ambient temperature + 4t, and ambient temperature - 4'C (t ermed ambient, warm and coo!, respectively, in the following text). Whole sporophytes were placed in 90 L tanks and cultured for 14 days. Evaluations of growth parameters are briefly presented in the foliowing (for detailed results see Manuscripts 1 & 2). OBJ la - Results and Interpretation: The results revealed that water temperatures between 12 1 and 20°C had only minor effects on the meristematic growth rates of Macrocystis spp., expressed as a daily blade elongation rate (BER) in cm d 1 (Fig. 1). However, water temperatures aboye 2M strongly influenced alga¡ degraciation and thus survival. At high water temperatures, floating individuals of Macrocystis spp. completely disintegrated and sank within 5 days (see Fig. 1, Iquique). Changes in algal biomass were dramatically different between the three locations. The alga¡ biomass (expressed as Percent biomass change d) considerably decreased at the warmest water temperature in Iquique (Fig. 2). In contrast, alga¡ biomass increased in Coquimbo and Valdivia. In Valdivia, alga¡ biomass continued to increase at ah temperatures (including the warm treatment) until day 10, even in the presence of grazers (Fig. 2). In Iquique, where algae were kept at warmer temperatures, algae continued to grow (albeit minimally - Fig. 1), but the biomass decreased dramatically under all experimental conditions (Fig. 2). In this case the high degradation rates could not be compensated by alga¡ growth. In Coquimbo alga¡ persistence mairily depends on the presence or absence of grazers. However, in Valdivia temperature throughout the tested temperature range and grazing seemed to have only minor impacts on alga¡ survival: algae grow and survive well due to very limited degradation rates. Physiological alga¡ responses were similar to growth responses of algae. Physiological performance of floating algae was favoured under optimal conditions such as low water temperatures and 10w hight levels, where algae were able to maintain a balance between the energy gained vía photosynthesis arid the energy used to cope with herbivores.The observed latitudinal persistence of floating Macrocystis spp. along the Chilean coast agrees with our previously predicted assumptioris that algae disintegrate at faster rates in warmer water temperatures (northern Chile) than algae kept at moderate and cooler water temperatures (central and south Chile). These results also agree with the findings of Vandendriessche et al. (2007) and Hobday (2000) that the decomposition rate of algae is temperature dependent. Using small-scale laboratory experiments, Vandendriessche et al. (2007) showed that alga¡ decomposition is minimal at 5 9C, and Hobd ay (2000) estimated that algal decomposition increase dramatically at temperatures abo ye 209C. Please find attached in the section products, subsection articles, Manuscript 1 & 2. OBJECTIVE lb (field): Examine the effect of qrazinc on floatinQ al pae in the natural environment. OBJ lb - Materials & Methods: In paraUel to the laboratory experiments, at ah three locations a field experiment was conducted. Three treatments were reahized, the Control (alga was kept in a mesh bag), Grazing (alga was kept in a mesh bag together with the amphipod grazer P. femorata) and Natural (alga was kept without a mesh bag). Each treatmerit was replicated 8-times. Algae were tethered in a protected bay and close to the location of the tank experiment to facilitate accessibility. OBJ lb - Results: Prehiminary results show that the natural environment (temperature and herbivory) had shight effects on BER and biomass change. In Iquique the BER only seemed to be affected by the naturally occurring grazers in the field (Natural-treatment) and by P. femorata (Grazing-treatment, see Fig. 3). BER was strongly influenced by the amphipods in Coquimbo after a floating period of only 7 days and algae were so heavily grazed by the end of the experiment that it was not possible to take blade measurements. In Valdivia, during the first 7 days of experimentation BER was constant for al¡ treatments and decreased thereafter in the control and grazing treatment. Biomass decreased in the presence of P. femorata during the first 7 days of floating time in Iquique and Coquimbo, but not in Valdivia. Biomass change became negative between day 7 and 15 of floating time at ah three locations (Fig. 4). In general, there is a tendency that the mesh bags slightly suppressed algal growth when compared to the Natural treatment. OBJ lb —Interpretation: There is evidence that raft persistence in Iquique and Coquimbo is affected by the presence of amphipod grazers. It is known that vegetative blades of Macrocystis integrifolia showed 10w defensive responses against amphipod grazers (Pansch et al. 2008) and thus were probably preferentially consumed by Peramphithoe femorata (Manuscript 3). At both sites (northern and central Chile) the loss of biomass was higher than in Valdivia. Biomass losses in Valdivia can probably be compensated by alga¡ growth. However, for alI three locations algae kept under natural conditions may survive. In our experiments original grazers had been removed from the experimental algae from the Natural" treatment, which may not be entirely representative of naturally floating algae, which usually contain sorne grazers. Fish predators around natural rafts may, though, keep local grazer stocks low. OBJECTIVE 2a (Iaboratory : Examine the effect of nutrients and temperature on floatinq algae. OBJ 2a - Materials & Methods: In order to determine the effects of nutrient availability and temperature on growth,