Eduardo Jaramillo

Diversity, dynamics and biogeography of Chilean benthic nearshore ecosystems: an overview and guidelines for conservation

A pesar de que Chile ha sido un pais pionero en estudios del efecto del impacto humano sobre la estructura comunitaria en ambientes marinos, y a pesar de la enorme importancia economica y social que el ambiente marino tiene para el pais, el desarrollo de programas de conservacion marina y de bases cientificas para la sustentabilidad no se han generado a la misma tasa a la que han explotado los recursos y se ha utilizado el ambiente costero para diversos fines. Aunque nosotros pensamos que el establecimiento de planes de conservacion a lo largo de la costa de Chile debe basarse en varios factores, los principios cientificos, biologicos y ecologicos deben guiar muchos de estos esfuerzos, y en este trabajo nosotros intentamos presentar una vision general del estado actual del conocimiento sobre la ecologia y la biogegrafia del sistema costero en Chile. En base a la informacion mas relevante existente, nuestros objetivos son: 1) identificar las caracteristicas biogeograficas y ecologicas del ecosistema costero y tambien vacios en informacion, 2) identificar las actividades humanas mas daninas que tengan impacto en la estructura y dinamica de estos sistemas, y 3) sugerir el uso de posibles indicadores para determinar la situacion de diferentes areas de la costa de Chile, y las necesidades de conservacion. Esta revision muestra, por un lado, areas geograficas con informacion critica deficitaria para planes futuros de manejo y conservacion marina , y por el otro lado, la disponibilidad de informacion de alta calidad para otras zonas geograficas del pais. Respecto de la informacion existente sobre taxonomia y patrones de distribucion de especies a gran escala, existen importantes vacios de informacion; no se esperan en el futuro grandes cambios en el numero total de especies. Existen pocos estudios sobre patrones de distribucion de especies a gran escala, y mas informacion es necesaria para identificar areas de alta diversidad de especies, especialmente para algunos taxa, como tambien para identificar areas que posean caracteristicas unicas en relacion a especies (endemicas, especies claves) y a procesos ecosistemicos (disturbios, surgencias). Para la mayoria de los invertebrados y macroalgas, las areas de alta diversidad de especies se encuentran en el sur de Chile. Nuevos estudios dirigidos a entender los factores que podrian generar patrones a macroescala son necesarios, como tambien informacion sobre oceanografia costera y disponibilidad de larvas. Esta informacion es clave para el diseno de una futura red de parques marinos. Por otro lado, la informacion disponible sobre estructuras comunitarias y funcionamiento ecosistemico, especialmente sobre el efecto del impacto humano, provienen de pocas regiones geograficas. Mas informacion sobre otras zonas geograficas es requerida, particularmente si se consideran las diferencias notables en temperatura, patrones de circulacion, heterogeneidad del habitat, y composicion de especies, como tambien el efecto de surgencia y de El Nino a lo largo de los mas de 4.000 km de costa de Chile. Finalmente, listamos las que consideramos son las actividades humanas mas daninas para el ambiente marino, e integramos esta informacion para sugerir posibles indicadores ambientales y necesidades basicas y sugerencias para conservacion marina in Chile

Adaptations of bivalves to different beach types

Burrowing ability, shape and density of 12 bivalve species from a wide range of beach types were compared as part of a general investigation of the adaptations of bivalves to the swash climates experienced on exposed sandy beaches. The genera used were Donax, Mesodesma, Tivela, Siliqua, Atactodea, Paphies and Donacilla. Burrowing rates varied widely and burrowing ability showed no relation to beach type along the reflective/dissipative beach gradient, i.e. from beaches with low wave energy and coarse sand to beaches with high wave energy and fine sand. Burrowing rate indices (BRIs) ranged from 2 to 17 (rapid to very rapid) and tended to be higher for juveniles of most species. Bivalve species from dissipative beaches varied in shape from almost blade-shaped to almost spherical, whereas those from reflective beaches were more uniform generally wedge-shaped. Species with the most flattened shapes and (greatest height/width ratios) tended to burrow fastest. Striking interspecific differences were found in densities of whole intact bivalves, these ranging from 1.04 g · cm−3 to 2.10 g · cm−3. The highest densities were recorded in bivalves from reflective beaches and the lowest in bivalves from dissipative beaches. Bivalve species typical of intermediate and reflective beaches were successfully separated from those typical of dissipative beaches on the basis of their density, morphology and BRI, particularly their size and density, using discriminant analysis. It is concluded that small species with high density and streamlined shape are best adapted to the dynamic swash conditions that characterise reflective beaches.

Ecological Implications of Extreme Events: Footprints of the 2010 Earthquake along the Chilean Coast

Deciphering ecological effects of major catastrophic events such as earthquakes, tsunamis, volcanic eruptions, storms and fires, requires rapid interdisciplinary efforts often hampered by a lack of pre-event data. Using results of intertidal surveys conducted shortly before and immediately after Chiles 2010 M w 8.8 earthquake along the entire rupture zone (ca. 34–38°S), we provide the first quantification of earthquake and tsunami effects on sandy beach ecosystems. Our study incorporated anthropogenic coastal development as a key design factor. Ecological responses of beach ecosystems were strongly affected by the magnitude of land-level change. Subsidence along the northern rupture segment combined with tsunami-associated disturbance and drowned beaches. In contrast, along the co-seismically uplifted southern rupture, beaches widened and flattened increasing habitat availability. Post-event changes in abundance and distribution of mobile intertidal invertebrates were not uniform, varying with land-level change, tsunami height and coastal development. On beaches where subsidence occurred, intertidal zones and their associated species disappeared. On some beaches, uplift of rocky sub-tidal substrate eliminated low intertidal sand beach habitat for ecologically important species. On others, unexpected interactions of uplift with man-made coastal armouring included restoration of upper and mid-intertidal habitat seaward of armouring followed by rapid colonization of mobile crustaceans typical of these zones formerly excluded by constraints imposed by the armouring structures. Responses of coastal ecosystems to major earthquakes appear to vary strongly with land-level change, the mobility of the biota and shore type. Our results show that interactions of extreme events with human-altered shorelines can produce surprising ecological outcomes, and suggest these complex responses to landscape alteration can leave lasting footprints in coastal ecosystems.

Give Beach Ecosystems Their Day in the Sun

The Intergovernmental Panel on Climate Change Fourth Assessment Report ([ 1 ][1]) largely overlooked the impacts of climate change on marine ecosystems ([ 2 ][2]). In their Review (“The impact of climate change on the worlds marine ecosystems,” 18 June, p. [1523][3]), O. Hoegh-Guldberg and J. F

The role of grazers in the zonation of intertidal macroalgae of the Chilean coast

The role of herbivores in maintaining the pattern of zonation of macroalgae in the mid-intertidal community of semi-exposed shores was studied during 8 months (January to September 1979). Herbivores were totally removed every 15 days from a semi-exposed intertidal rocky wall, while another wall served as a control. Percent cover of algae was measured at two month intervals. Herbivore removal resulted in a disruption of the pattern of zonation. Iridaea boryana and Gymnogongrus furcellatus expanded the width of their belts into the zone initially occupied only by Ulva rigida and Lithophyllum spp. We conclude that herbivory is the basic mechanism which maintains the limits between the zones of these macroalgae in southern Chile.

Community structure of the intertidal meiofauna along a gradient of morphodynamic sandy beach types in southern Chile

Se estudiaron tres playas arenosas del sur de Chile (Gaviotas, Guabun y Mar Brava; ca. 42o S) durante el verano del 2000 para analizar los patrones de abundancia y biomasa de la meiofauna a lo largo de un gradiente de tipos morfodinamicos de playas. Se recolectaron muestras de sedimento con cilindros metalicos (23 cm2 de area, 120 cm de longitud) en diez niveles espaciados a intervalos regulares a lo largo de seis transectos separados de 5 a 10 m y extendidos desde un punto sobre el nivel de marea alta y el nivel de marea baja. En cada nivel de muestreo se midio porosidad, fuerza de cizalla, contenido de agua, penetrabilidad y tamano del grano. La meiofauna estuvo primariamente representada por Nematoda y Copepoda Harpacticoidea. Las mayores densidades y biomasas medias por unidad de area se encontraron en la playa reflectiva de Gaviotas (6.172 ind 10 cm-2 y 2,38 g m-2, peso seco libre de cenizas) en comparacion con la playa intermedia de Guabun (3.390 ind 10 cm-2 y 1,70 g m-2) y la playa disipativa de Mar Brava (3.667 ind 10 cm-2 y 0,86 g m-2). La abundancia y biomasa total de la meiofauna por metro lineal de playa (i.e., meiofauna total contenida en un transecto intermareal de 1 m de ancho) fueron mayores en Mar Brava (506 x 106 ind m-1 y 119,4 g m-1) versus Gaviotas (271 x 106 ind m-1 y 101,7 g m-1) y Guabun (143 x 106 ind m-1 y 73,9 g m-1). Por lo tanto, estos ultimos resultados muestran una tendencia de aumento de abundancia y biomasa de la meiofauna intermareal hacia el tipo disipativo dentro del gradiente estudiado de tipos de playas. Los valores mas altos de densidad y biomasa de la meiofauna se encontraron en los niveles superiores y medio de cada playa. En la playa disipativa, se encontro la menor variabilidad en abundancia y biomasa de la meiofauna a lo ancho del intermareal. Segun la prueba de permutacion de Monte Carlo, el contenido de agua, penetrabilidad y tamano del grano fueron las variables que mejor predicen la variabilidad de las densidades de la meiofauna. Los tamanos corporales de nematodos, copepodos, turbelarios, halacaridos y ostracodos estuvieron correlacionados con las caracteristicas del sedimento. En general, las relaciones entre estructura comunitaria de la meiofauna y morfodinamica de playas, fueron similares a aquellas encontradas para la macroinfauna de diferentes playas arenosas alrededor del mundo, lo que sugiere que la meiofauna y macroinfauna son afectadas similarmente por los procesos fisicos asociados a diferentes tipos de playas

Locomotor activity and zonation of upper shore arthropods in a sandy beach of north central Chile

Abstract The tenebrionid beetle Phalerisida maculata Kulzer, the talitrid amphipod Orchestoidea tuberculata Nicolet and the oniscid isopod Tylos spinulosus Dana are semi-terrestrial burrowing species, which coexist on sandy beaches of north central Chile (28–30°S). During the night, these scavengers emerge to make downshore migrations. Given the similarity in niches of these three species (all are known to include macroalgal detritus in their diet) and their relatively high abundance on that beaches, there is the potential for some degree of interaction, both inter- and intraspecific. Field studies were carried out to examine zonation of these burrowing organisms and eventual time and/or space partitioning of locomotor activity during night hours. Locomotor activity on the beach surface was analyzed over 12 h periods during spring and neap tides of September and December 2000, and March 2001. Scavengers moving over the beach surface were captured using pitfall traps buried with their rims flush with the beach surface along a transect extended from the foot of the dunes to the highest levels reached by the swashes. Every 1 h the captured animals in the traps were collected. Locomotor activity was also studied in the laboratory with chambers equipped with infrared recording systems (actographs). Data downloaded from the actographs were graphed to obtain a display of locomotor activity per 15 min interval during the course of the 7 day experiments. Results show space partitioning of burrowed organisms and time partitioning in the locomotor activity of O. tuberculata , T. spinulosus and P. maculata over the beach surface. Circular statistics showed that usually the activity peaks of O. tuberculata were more different from those of P. maculata and T. spinulosus than those of the last two species when compared with each other. Intraspecific differences were also found in the surface locomotor activity, primarily between juveniles and adults of O. tuberculata . Interseasonal comparisons of capture figures show that the highest locomotor activity occurred during early summer (December 2000). Moon phases apparently affect locomotor activity (i.e. T. spinulosus and P. maculata had higher locomotor activity during neap tides as compared with that observed during spring tide samplings carried out with full moon). Periodograms resulting from the locomotor activity of adults of O. tuberculata , T. spinulosus and P. maculata studied with actographs and total darkness show evidence of a circadian endogenous component close to 23–25 h. Activity peaks close to 11–14 h were also found that probably represents a circatidal component in the locomotor activity. Results of actograph experiments under constant light show that the circadian rhythm of locomotor activity of O. tuberculata was the only one maintained throughout the experiment and phased with the subjective night. Analyses of contour distributional maps and mean hourly zonations show that the locomotor activity of the studied species also differed, specially that of O. tuberculata versus that of T. spinulosus and P. maculata . Results of coexistence experiments showed no evidence of intraspecific interactions. Similar experiments evidentiated interspecific interactions: those species with similarities in locomotor activity (that is T. spinulosus and P. maculata ) showed no interactions between them, while both of them had negative interactions with O. tuberculata , the species which separated more in time and hourly zonation of locomotor activity. Thus, differences in time/space partitioning of surface locomotor activity can be interpreted as a means to avoid detrimental interactions in this guild of scavengers. That partitioning would allow coexistence of interacting scavenger species and provides evidence that biological interactions are indeed important in community structure of sandy beach macroinfauna.

Environmental processes, water quality degradation, and decline of waterbird populations in the Rio Cruces wetland, Chile

Changes in wetland ecosystems may result from the interactions of endogenous processes with exogenous factors such as environmental fluctuations and anthropogenic influences. Since mid-2004, the Río Cruces wetland, a Ramsar site located in southern Chile (40°S), exhibited a sudden increase in mortality and emigration of the largest breeding population of Black-necked swans in the Neotropics, a massive demise of the dominant macrophyte Egeria densa (the main food of swans and several aquatic birds), and a seasonal appearance of turbid waters. We compared annual variation in rainfall, river flow, and radiation over the period 2000–2005 to assess the role of environmental factors on these wetland changes. Those factors, with the exception of a decrease in river flow during 2004, did not show significant inter-annual differences. However, when comparing Landsat images, we found in the visible and near-infrared spectrum, a corresponding increase and decrease in water reflectance for 2005 with respect to 2003 and 2001, respectively. These results may reflect the appearance of turbid waters and the decrease in cover of E. densa. All temporal changes were restricted to the northern and central zones of the wetland. In addition, spatial analysis showed a gradient in turbidity across the wetland waters, which was enhanced by estuarine influence during spring-tides. Censuses of aquatic birds (1999–2005) showed that only herbivorous birds exhibited a pronounced decrease in population abundance after mid-2004, while piscivorous birds continued normal cycling, with even some positive trends in abundance during 2004–2005. Population declines in herbivorous birds may be related to the demise of E. densa and suspension of sediments during periods of reduced river flow (2004) that gave rise to the turbidity in the wetland waters. Environmental changes could be related to changes in water quality after a new pulp mill, built upstream of the wetland, initiated operations during February 2004.

Algal wrack deposits and macroinfaunal arthropods on sandy beaches of the Chilean coast

Se muestrearon cuatro playas arenosas del litoral chileno durante el verano de 2000, para estudiar el rol de depositos de algas varadas sobre las abundancias de las poblaciones de tres especies detritivoras de la macroinfauna que habita los niveles intermareales superiores de estas playas: el anfipodo talitrido Orchestoidea tuberculata Nicolet, el isopodo tilido Tylos spinulosus Dana y el insecto tenebrionido Phalerisidia maculata Kulzer. Las playas estudiadas fueron Apolillado (ca. 29o S), Quidico (ca. 38o S), Guabun y Mar Brava (ca. 42o S). Se recolectaron muestras replicadas con un cilindro plastico (25 cm de diametro) de los depositos de algas, incluyendo el sedimento situado por debajo de los mismos y de zonas de la playa proximas a los acumulos de algas pero carentes de las mismas. Las muestras se recolectaron en dos niveles de la playa, uno mas proximo a la orilla con acumulos de algas frescas y otro en la zona superior de la playa con algas secas. Los depositos de algas varadas estuvieron compuestos principalmente por las algas pardas Macrocystis pyrifera (L.), Durvillaea antarctica (Chamisso) Hariot y Lessonia nigrescens Bory. O. tuberculata fue encontrada en los depositos de algas y zonas de la playa cercanas a los mismos y estudiados en Apolillado, Quidico, Guabun y Mar Brava. Por otro lado, T. spinulosus fue recolectada solo en Apolillado, mientras que P. maculata ocurrio en los depositos de algas y zonas de la playa cercanas a los mismos y analizados en Apolillado, Quidico y Guabun. En general, las abundancias medias de las tres especies fueron significativamente mas altas en aquellas muestras recolectadas de los depositos de algas y sedimentos subyacentes; i.e., 56, 61 y 14 veces mas altas (promedios totales) que en arenas sin restos de algas. Se concluye que las algas varadas sobre la superficie de la playa promueven un incremento de las abundancias poblacionales de los detritivoros de playas arenosas, ya sea porque representan la fuente principal de alimento para estos organismos o porque proveen de refugio, ante, por ejemplo, condiciones ambientales variables (e.g., temperatura, humedad) durante las horas del dia. Lo anterior puede explicar la distribucion en parches que presentan estos organismos, tanto a lo largo como a lo ancho del intermareal. Esta conclusion tiene implicaciones importantes para el diseno de muestreos en playas arenosas caracterizadas por un elevado aporte de depositos de algas varadas sobre el intermareal

Population abundances, growth and natural mortality of the crustacean macroinfauna at two sand beach morphodynamic types in southern Chile

Se realizaron muestreos mensuales durante 1994-1996 en una playa arenosa intermedia y en una playa disipativa del sur de Chile (Calfuco y Mehuin, respectivamente; ca. 39o S), para evaluar las predicciones de la hipotesis de exclusion por la resaca sobre las abundancias poblacionales e historia de vida de la macroinfauna de crustaceos que habita en el intermareal de esas playas. Se hipotetiza que solo las especies realmente intermareales (i.e., directamente afectadas por la resaca) son afectadas por diferencias en los tipos morfodinamicos de playas. Esas especies fueron los isopodos cirolanidos Excirolana braziliensis y Excirolana hirsuticauda y el cangrejo anomuro Emerita analoga. Por otra parte, el anfipodo Orchestoidea tuberculata (mayoritariamente supralitoral) no debiera ser afectado por diferencias en tipos morfodinamicos de playas. Las abundancias poblacionales totales de O. tuberculata y E. analoga fueron significativamente mas altas en la playa intermedia de Calfuco, las de E. braziliensis y E. hirsuticauda en la playa disipativa de Mehuin. Mientras que las abundancias de las hembras ovigeras de O. tuberculata y E. analoga fueron mas altas en Calfuco, las de las hembras ovigeras de E. braziliensis y E. hirsuticauda no difirieron entre playas. Los juveniles de O. tuberculata fueron mas abundantes en Calfuco, mientras que los de las otras especies en Calfuco. Los maximos en los periodos reproductivos de anfipodos e isopodos ocurrieron durante los mismos meses de primavera-verano en ambas playas. El periodo reproductivo de E. analoga tambien ocurrio durante primavera-verano, pero los maximos de abundancia ocurrieron en meses diferentes. Mientras que las maximas abundancias de los juveniles de O. tuberculata ocurrieron en periodos similares, las de los juveniles de Excirolana braziliensis y E. hirsuticauda ocurrieron mas tarde en Mehuin. Los juveniles de E. analoga tuvieron abundancias muy bajas durante el primer periodo primavera-verano; durante el segundo, mostraron sus maximas abundancias durante octubre en ambas playas. Las curvas de crecimiento y parametros de crecimiento de O. tuberculata, E. braziliensis y E. hirsuticauda no difirieron significativamente entre playas, aun cuando O. tuberculata tendio a crecer mas rapido en Calfuco. Las curvas de crecimiento y parametros de crecimiento de E. analoga fueron diferentes solo para las hembras, las que tuvieron mayor crecimiento en el sitio disipativo. Las mortalidades naturales de las cuatro especies no difirieron significativamente entre playas. Asi, la mayoria de nuestros resultados no soportan nuestra hipotesis, sugiriendo que otros factores, aparte de las morfodinamica de la playa, son importantes en explicar la variabilidad espacial en las abundancias poblacionales y biologia poblacional de la macroinfauna de playas arenosas