Guillermo Luna-Jorquera

Anthropogenic debris on beaches in the SE Pacific (Chile): Results from a national survey supported by volunteers

Anthropogenic marine debris (AMD) is an ubiquitous problem, which has motivated public participation in activities such as beach surveys and clean-up campaigns. While it is known that beaches in the SE Pacific are also affected by this problem, the quantities and types of AMD remain largely unknown. In the context of an outreach project, volunteers (approximately 1500 high-school students) participated in a nation-wide survey of AMD on 43 beaches distributed randomly along the entire Chilean coast (18 degrees S to 53 degrees S). The mean density of AMD was 1.8 items m(-2) and the major types were plastics, cigarette butts and glass. Densities in central Chile were lower than in northern and southern Chile, which could be due to different attitudes of beach users or to intense beach cleaning in central regions. We suggest that public participation in surveys and cleaning activities will raise awareness and thereby contribute to an improvement of the situation.

Seasonal and Regional Variation in the Diet of the Kelp Gull in Northern Chile

Abstract The feeding ecology of the Kelp Gull (Larus dominicanus) was studied during the 2002-03 breeding season at Coquimbo, northern Chile. Food composition was studied by analyzing pellets regurgitated by Kelp Gulls living in different habitats. Birds breeding or resting near fishing ports used these as their main feeding grounds. Birds breeding on offshore islands fed mainly on intertidal organisms and olives. A comparison between the food of breeders and non-breeding birds during the breeding season showed a difference in diet composition of breeders, who fed more on fish of high energy density while non-breeding birds continued feeding on a wide range of organisms and waste. Observations in a fishing harbor and at sea demonstrated that fisheries waste was an important food source for the birds. The inshore distribution at sea was related to the location of fishing ports and breeding colonies.

Population size of Humboldt penguins assessed by combined terrestrial and at-sea counts

-The Humboldt Penguin (Spheniscus humboldti) has been reported as declining along its distributional range and has recently been classified as vulnerable. The actual size of the Humboldt Penguin population is still unknown, and a complete population assessment is required. Here we present a study combining both counts of molting birds on land and counts of birds at sea during the molting period. We conducted our study in the Coquimbo Region, Northern Chile, and found 7,619 birds on land and 2,700 at sea, adding up to a total of about 10,300 Humboldt Penguins during the molting season (February 1999). Since these numbers are much higher than all other recent estimates, we emphasize that assessment on land and at sea need to be combined to provide more reliable estimates. Received 20July 1999, accepted 15July 2000.

Observations on the thermal conductance of Adélie (Pygoscelis adeliae) and Humboldt (Spheniscus humboldti) penguins

Analyses of cooling rates in one Adélie and one Humboldt penguin yielded calculated thermal conductance values of 0.1040 and 0.1672 W(kg °C)-1, respectively. We review the methods used to calculate penguin surface area, an important component in calculating conductance values, and suggest that, in comparative studies of thermal balance, the use of body mass is a better estimator of body size than surface area. Using previously published data on penguin species, we found a significant model to predict thermal conductance from body mass according to: log C= log 0.1083−0.474 log M, where C is minimal specific thermal conductance in W(kg °C)-1 and M is body mass in kilograms.

The Humboldt penguinSpheniscus humboldti: a migratory bird?

Until recently, the endangered Humboldt penguin was considered a sedentary bird, which remained near its breeding colonies throughout the year. In this pilot study we used five satellite transmitters on Humboldt penguins during the austral winter and were able to track one bird from Pan de Azúcar Island (26°09′S, 70°40′W), Northern Chile to Iquique (20°12′S, 70°07′W), a distance of 640 km, between May 24 and June 26, 1996. While a 35 km protection zone around breeding islands might be helpful to prevent competition of penguins with fisheries during the summer months, this might not improve the survival of migrating birds in the winter. Further studies are required to determine the extent of migration and to confirm the recorded travelling route and landing locations in order to detect possible threats to Humboldt penguins from fishing and other industries throughout the year. Während noch vor wenigen Jahrzehnten Millionen Humboldtpinguine die Küsten Perus und Chiles bevölkerten, wird die Art heute als gefährdet eingestuft. Die Fischerei stellt die größte Bedrohung für diese Tierart dar, deren Gesamtbestand sich nach letzten Schätzungen nur noch auf 10 000 Individuen beläuft. Wir setzten im Südherbst 1996 fünf Argos-Satellitensender ein, um festzustellen, ob Humboldtpinguine des Naturschutzgebietes „Pan de Azúcar“ (26°09′S) im Winter ortstreu bleiben oder saisonale Wanderungen durchführen. Während sich vier der Vögel im Untersuchungszeitraum (18–74 Tage) nicht weiter als 87 km von ihrer Brutinsel entfernten, wanderte ein Vogel im Juni 1996 nach Norden bis vor die Stadt Iquique (20° 12′S, 640 km vom Ausgangspunkt entfernt). Obwohl die in einer früheren Studie ermittelte Größe eines marinen Schutzgebietes von 35 km Durchmesser rund um die Brutinsel in den Sommermonaten ausreichend sein mag, belegen die neuen Ergebnisse, daß weitere Untersuchungen über das Wanderverhalten der Humboldtpinguine als Grundlage für einen effektiven Artenschutz unerläßlich sind.

Seasonal variations in the behavioural thermoregulation of roosting Humboldt penguins (Spheniscus humboldti) in north-central Chile

We examined the thermoregulatory behaviour (TRB) of roosting Humboldt penguins (Spheniscus humboldti) in north central Chile during summer and winter, when ambient temperatures (Ta) are most extreme. Each body posture was considered to represent a particular TRB, which was ranked in a sequence that reflected different degrees of thermal load and was assigned an arbitrary thermoregulatory score. During summer, birds exhibited eight different TRBs, mainly oriented to heat dissipation, and experienced a wide range of Ta (from 14 to 31°C), occasionally above their thermoneutral zone (TNZ, from 2 to 30°C), this being evident by observations of extreme thermoregulatory responses such as panting. In winter, birds exhibited only three TRBs, mainly oriented to heat retention, and experienced a smaller range of Ta (from 11 to 18°C), always within the TNZ, even at night. The components of behavioural responses increased directly with the heat load which explains the broader behavioural repertoire observed in summer. Since penguins are primarily adapted in morphology and physiology to cope with low water temperatures, our results suggest that behavioural thermoregulation may be important in the maintenance of the thermal balance in Humboldt penguins while on land.

Humboldt Penguin Census on Isla Chañaral, Chile: Recent Increase or Past Underestimate of Penguin Numbers?

Abstract While Isla Chañaral (29°02’S) in Chile has long been recognized as one of the most important breeding islands for the Humboldt Penguin, the reported numbers of birds there never exceeded 3,500 breeding individuals in the last two decades. However, in 2002, a one-day survey found considerably more penguins present on Isla Chañaral, which exceed the world population estimate for the species (3,300-12,000 birds). Between 9 and 14 February 2003 we conducted a census of the Humboldt Penguin on Isla Chañaral. Two different survey methods were combined to assess the number of penguins. Terrestrial or surface counts were used to survey penguins on open plains or beaches. Small area surveys of randomly established quadrats were conducted to assess the density of penguins in nests and the total number of nest sites. Results from small area surveys were extrapolated using surface size ratios of counting quadrats vs. entire nesting sectors. We determined that approximately 22,000 adult Humboldt Penguins, 3,600 chicks and 117 juveniles were present on the island during the survey. The results were much higher than any previously published estimate. Natural processes alone cannot account for an increase, and penguin numbers on Isla Chañaral previously have been underestimated. The results correspond well with recent publications that suggest that Humboldt Penguin numbers in Chile have been underestimated in the past due to inappropriate or inconsistent census methods. There are concerns about the current protection status of the island in light of its fragility and importance as the premier breeding location of the Humboldt Penguin along its entire distributional range.

Litter and seabirds found across a longitudinal gradient in the South Pacific Ocean.

Abundances and composition of marine litter and seabirds were estimated in the central South Pacific (SP) Ocean between the Chilean continental coast and the Easter Island Ecoregion. Litter was dominated by plastics throughout the study area, but the proportion of plastics was higher at sea and on the oceanic islands than in coastal waters and on continental beaches. Litter densities were higher close to the center of the SP subtropical gyre compared to the continental coast. The seabird assemblage was diverse (28 species), and several endemic species were recorded. Seabird abundances were higher in the coastal waters and around Juan Fernández Islands off the continental coast than in the Oceanic and Polynesian sectors. Endangered species breeding on Salas & Gómez Island were observed in the Polynesian sector, which suggests a high potential for negative interactions between seabirds and floating litter, both occurring in high densities in this sector.

Daily and seasonal changes of photobiological responses in floating bull kelp Durvillaea antarctica (Chamisso) Hariot (Fucales: Phaeophyceae)

Abstract: Floating seaweeds are important dispersal vehicles, especially for organisms with limited movement capacities and for the seaweeds themselves. The persistence of floating seaweeds is determined by the balance between their acclimation potential and the environmental pressures at the sea surface. Solar radiation is the most important inducer of physiological stress, varying in intensity throughout the day and the year. Therefore photoinhibition and subsequent recovery can change depending on the daily radiation dose and season. The bull kelp Durvillaea antarctica is one of the most common floating seaweeds in the southern oceans, including New Zealand, Chile, and most subantarctic islands. Herein, daily cycles of maximum quantum yield (Fv/Fm), photoinhibition and recovery levels were examined in microcosm experiments with floating D. antarctica throughout the year, focusing on the blade side exposed to solar radiation (sunny vs shadow side). Also, the effect of simulated wave action (blade turnover) and ultraviolet radiation (UVR) on photoinhibition and recovery of Fv/Fm was evaluated. Significant differences in maximum quantum yield were observed between blade sides, with lowest values on the sun-exposed side, especially during noontime and spring/summer months. Phlorotannins and pigments were measured during seasons with the most intense solar radiation (late spring, early summer), when Fv/Fm values were lowest. Phlorotannin, but not pigment concentrations, differed between sunny (lower concentration) and shadow blade sides (higher concentration) and throughout the daily cycle. Both blade sides had similar photoinhibition and recovery levels when blades were constantly turned over. Absence of UVR favoured the recovery capacity of Fv/Fm in both blade sides, suggesting that the photorecovery potential of floating kelps depends on the environmental conditions that kelp rafts face at the sea surface (e.g. cloudy vs sunny days, intense seawater movement and splashing vs calm sea conditions). The results confirm that photobiological stress is more severe during summer and on continuously sun-exposed blade sides, thereby damaging the blades and suppressing the floating time of D. antarctica.

Distribution and Trends in Kelp Gull (Larus dominicanus) Coastal Breeding Populations in South America

Abstract. In South America, Kelp Gulls (Larus dominicanus) breed from Chilean Tierra del Fuego north to Río de Janeiro, Brazil, on the Atlantic coast and to Piura, Peru, on the Pacific coast. This review presents the first synthesis of information on the distribution and size of Kelp Gull colonies at the country level in coastal environments of Uruguay, Chile and Peru; provides an update on the breeding situation of the species in Brazil and Argentina; and allows the first evaluation of the overall coastal breeding population in South America. The breeding population in South America is now estimated to number at least 160,000 pairs. The largest population (at least 106,000 breeding pairs) is found in Argentina. Colonies of more than 1,000 pairs are uncommon. Population trends differed among coastal sectors, and important increases in numbers and formation of new colonies were only observed in Argentina. Available information suggests that predictable and abundant anthropogenic food subsidies, such as fishery discards and urban waste, are key factors contributing to the population growth in some coastal sectors. There is no strong evidence that Kelp Gulls are currently expanding their breeding range. However, given the population expansion in some areas and the potential conflicts with humans, ongoing monitoring efforts and population evaluations are necessary as they will provide the information required to support management decisions.