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Examinando Articulos Institucionales de Impacto por Materia "Earth and Planetary Sciences"
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Ítem Acceso Abierto Aerial behavior of humpback whales Megaptera novaeangliae at the southern limit of the southeast Pacific breeding area [Comportamiento aéreo de la ballena jorobada Megaptera novaeangliae en el límite sur de la zona reproductora en el Pacífico sureste](2013) Pacheco, A.S.; Silva, S.; Alcorta, B.; BalduccI, N.; Guidino, C.; Llapapasca, M.A.; Sanchez-Salazar, F.We evaluated the set of aerial displays shown by humpback whales Megaptera novaeangliae in the northern coast of Peru, a region that is considered the southern limit of the breeding area of the stock G in the Southeast Pacific. From August to October 2010, aerial displays were quantified from a whale-watching boat together with shore sightings. Our results indicated that the most frequent aerial display was breaching, followed by tail and flipper splashing. The maximum number of displays occurred in September. Groups made of pairs of whales performed the most frequent aerial behavior during the study period. Our results contrast with previous information off Ecuador suggesting that most intense aerial displays are performed when humpbacks are gathered in larger groups (more than 3 whales). These results add new information about humpback whales aerial behavior in the northern coast of Peru.Ítem Acceso Abierto Application of biochars to sandy and silty soil failed to increase maize yield under common agricultural practice(Elsevier, 2014) Borchard, N.; Siemens, J.; Ladd, B.; Möller, A.; Amelung, W.Adding biochar to tropical soils is a strategy for improving crop yield and mitigating climate change, but how various biochar types affect crop yield and the properties of temperate soils is still in dispute. Here, we evaluated how slow-pyrolysis charcoal and two biochars derived from energy production (gasification coke and flash-pyrolysis char) affected the growth of Zea mays L. and the related properties of sandy and silty soils within a 3-year mesocosm experiment. Fertilization was performed to optimize plant growth as would be done under common agricultural practice. Analyses included the monitoring of yield, plant and soil nutrients, aggregate stability, cation exchange and water holding capacity, and black carbon content. The results showed that the added biochars did not affect crop yield at an application rate of 15gbiocharkg-1 of soil. Increasing the application rate of slow-pyrolysis charcoal to 100gkg-1 resulted in decreased plant biomass in the second and third year of the experiment, likely as a result of nutrient imbalances and N-immobilization. We did not detect any degradation of the added black carbon; however, beneficial effects on plants were limited by the small and transient effect of these biochars on the physical and chemical properties of soil. Overall, our results indicate that the added carbon from biochars is stored in soil, but all treatments tested failed to improve plant yield for the studied temperate soils under the given application rates and common agricultural practice. © 2014 Elsevier B.V.Ítem Acceso Abierto Distribution and habitat use of a cryptic small cetacean, the Burmeister's porpoise, monitored from a small-scale fishery platform(Frontiers Media S.A., 2018) Clay, T.A.; Mangel, J.C.; Alfaro-Shigueto J.; Hodgson, D.J.; Godley, B.J.There is widespread evidence that small-scale fisheries (SSF) bycatch threatens many populations of small cetaceans, yet conservation efforts are often limited by a lack of basic knowledge regarding their abundance, distribution, and habitat use. Here, we used passive acoustic monitoring from an SSF platform-of-opportunity to better characterize the distribution and habitat use of small cetaceans in northern Peru, focussing on the little-known Burmeister's porpoise Phocoena spinipinnis. From 2009 to 2012, acoustic click detectors (C-PODs) were attached to fishing nets for the duration of 116 fishing sets (30 fishing trips). Dolphins (unspecified delphinids) and porpoises were recorded around 71 and 22% of fishing sets, respectively. The probability of occurrence and buzzing behavior (a proxy for foraging), and time spent, were linked to both static and dynamic environmental variables to examine the drivers of habitat use. Dolphin activity was spread evenly throughout the fishing area and was not linked to any habitat variables. In contrast, porpoises were detected in neritic waters, and habitat models performed well, identifying preferences for shallow (< 200 m depth) and cooler (17-18°C) waters, close (< 50 km) to shore. The high bycatch rate of small cetaceans in Peruvian SSF gave us the unique opportunity to investigate the link between bycatch and cetacean activity around vessels. We found a positive relationship between the likelihood of a bycatch event and acoustic presence for both dolphins and porpoises, however as we did not know the timing of entanglement, we could not link vocalization rates to mortality events. Nonetheless, as small cetaceans (particularly dolphins) frequently encounter fishing boats, the likelihood of entanglements may be reduced through effective efforts to alert animals to the presence of the net, either acoustically (using acoustic alarms) or visually. This study demonstrates that passive acoustic monitoring from a fisheries platform can provide insights into the distribution and habitat use of small cetaceans at relatively low cost, and is likely to be suitable in regions with low monitoring effort and high fishing pressure. © 2018 Clay, Mangel, Alfaro-Shigueto, Hodgson and Godley.Ítem Acceso Abierto Feeding ecology of the green turtle Chelonia mydas in northern Peru(Escuela de Ciencias del Mar, 2017) Jiménez, A.; Pingo, S.; Alfaro-Shigueto, J.; Mangel, J.C.; Hooker, Y.Diet and food preferences of the green turtle Chelonia mydas were analyzed based on digestive tract contents of dead specimens caught incidentally by an artisanal gillnet fishery in Sechura Bay, northern Peru. We examined 27 digestive tracts and identified 35 prey items. The sampled turtles were all juveniles (CCL = 53.7 ± 1.2 cm, range 40.5-67.0 cm). The prey items were grouped into six categories: algae, cnidarians, mollusks, arthropods, chordates and garbage/anthropogenic debris. The items with the highest Frequency of Occurrence values (% FO) were: Caulerpa filiformis (77.8%), Loligo gahi (eggs) (51.9%) and Rhodymenia corallina (44.4%). By weight (% W), the most important items, were L. gahi (eggs) (33.3%), Stomolophus sp. (7.3%) and Aphos porosus (6.5%). According to the Preponderance Index (%IP), the preponderant item was L. gahi (eggs) with 6.1% and 61.2% during winter-spring and summer-autumn, respectively. According to the Resultant Weight index (Rw) of wet items, the most important items were: C. filiformis (13.1%), L. gahi (eggs) (10.5%), R. corallina (7.4%), plastic (7.5%), Gigartina chamissoi (5.1%). Garbage/anthropogenic debris was common in the digestive tracts analyzed. Plastic items had a frequency of occurrence of 44.4%. A greater diversity of food items was observed during summer and autumn. This study shows that juvenile C. mydas forage on a variety of resources. We recommend that conservation plans, land use planning and future management plans in the Sechura Bay include green turtles as a sentinel species for monitoring biodiversity of marine resources and the degree of pollution in the Bay. © 2017, Escuela de Ciencias del Mar. All rights reserved.Ítem Acceso Abierto Filling the gaps in sea turtle research and conservation in the region where it began: Latin America(Escuela de Ciencias del Mar, 2017) Velez-Zuazo, X.; Mangel, J.C.; Seminoff, J.A.; Wallace B.P.; Alfaro-Shigueto, J.The first documented long-term sea turtle research and conservation project in the world was officially launched in Latin America (Tortuguero, Costa Rica) in 1955. Despite the enormous advances in research and conservation in the nearly seven decades since, many questions still remain unanswered about fundamental aspects of ecology and population dynamics that hinder the conservation of sea turtles in the region. To catalyze further dissemination of information and improvement of sea turtle conservation, this Special Issue presents 10 papers solely focused on studies conducted in Latin America. This Special Issue resulted from an initiative launched to celebrate the 36th Annual Symposium on Sea Turtle Biology and Conservation, held in Peru in March 2016 -the first time this event was held in South America. The articles featured present novel results for four of the five species of sea turtles present in this region, with data collected as far back as 1971 and as recent as 2016. The studies cover diverse subjects including the nesting ecology for the most endangered populations of sea turtles in the world - the Eastern Pacific hawksbill turtle (Eretmochelys imbricata) and leatherback turtle (Dermochelys coriacea); the origins and connectivity of nesting and foraging populations of hawksbills and green turtles (Chelonia mydas); the detection of a new foraging ground for hawksbills in the Eastern Pacific; and the pervasive occurrence of incidental capture as well as illegal retention of sea turtles. The recovery of these imperiled marine reptiles relies on information to design and implement sound conservation actions; in this regard, the papers in this Special Issue are making a vital contribution, following the initial efforts launched nearly 70 years ago. © 2017, Escuela de Ciencias del Mar. All rights reserved.Ítem Acceso Abierto Incidental capture of sea turtles in the artisanal gillnet fishery in Sechura Bay, northern Peru(Escuela de Ciencias del Mar, 2017) Pingo, S.; Jiménez, A.; Alfaro-Shigueto, J.; Mangel, J.C.Gillnets are recognized globally as one of the fishing gears with the highest levels of bycatch and mortality of sea turtles. Through onboard observer monitoring from July 2013 to June 2014 we assessed the bycatch of sea turtles by an artisanal gillnet fishery operating from Sechura Bay, Peru. One hundred and four sea turtles were incidentally caught in 53 observed fishing sets. The observed species composition of bycatch was green turtle Chelonia mydas (n = 100), hawksbill Eretmochelys imbricata (n = 3) and olive ridley Lepidochelys olivacea (n = 1). Bycatch occurred in 62.3% of monitored sets, with an average of 1.96 turtles caught per set. For all sea turtles combined, 28.8% of individuals were dead and 71.2% were alive at the time of retrieval. The majority of individuals caught were classified as juveniles and sub-adults, with an average carapace length (CCL) of 57.3 ± 0.9 cm for green turtles and 40.2 ± 2.4 cm for hawksbills. The mean annual catch per unit effort (CPUE) of sea turtles was 1.11 ± 0.31 turtles km-1 12 h-1), but varied by seasons. These results suggest that Sechura Bay is an important developmental habitat for juvenile and sub-adult green turtles and hawksbill turtles, but one subject to intense fishing interaction pressure. The development of monitoring programs, local awareness-raising activities, and enhanced management and protection of this critical foraging area and developmental habitat is recommended. © 2017, Escuela de Ciencias del Mar. All rights reserved.Ítem Acceso Abierto Isotopic niches of four commercially important pelagic elasmobranch species captured by the small-scale driftnet fishery of northern Peru(Escuela de Ciencias del Mar, 2018) Alfaro-Cordova, E.; Del Solar, A.; Gonzalez-Pestana, A.; Alfaro-Shigueto|, J.; Mangel, J.C.Despite the high landings of elasmobranch in Peru, little is known about some aspects of their basic biology, including their trophic ecology. The present study aims to provide basic information regarding the isotopic niche and trophic interactions of four pelagic elasmobranchs of commercial importance in northern Peru (Alopias spp., Galeorhinus galeus, Sphyrna zygaena, and Mobula japanica). One hundred and twenty-four samples were collected from fishing activities between January and December 2015 and processed for stable isotopes analysis (δ13C and δ15N), using Bayesian statistics to describe their isotopic niche. Differences between species were assessed using PERMANOVA and PERMDISP, allowing testing length, sex, and latitude as covariates. These combined results suggest trophic redundancy among sharks. However, unique areas of no overlap in the SEAC of all species could evidence a broad niche with a low interaction between these sharks. M. japanica had no overlap with any shark species, which indicates a trophic niche that is distinct from other elasmobranch top predators. Increasing sample size and including temporal covariates should help define these isotopic niches better, either by merging or splitting the studied elasmobranchs into more specific groupings. Further complementary studies are required to better understand trophic interactions within the pelagic community ecosystems. © 2018, Escuela de Ciencias del Mar. All rights reserved.Ítem Acceso Abierto Living on the edge: Hawksbill turtle nesting and conservation along the Eastern Pacific Rim(Escuela de Ciencias del Mar, 2017) Gaos, A.R.; Liles, M.J.; Gadea, V.; De Niz A.P.; Vallejo, F.; Miranda, C.; Darquea, J.J.; Henriquez, A.; Altamirano, E.; Rivera A.; Chavarría S.; Melero, D.; Urteaga J.; Pacheco, C.M.; Chácon, D.; LeMarie, C.; Alfaro-Shigueto, J.; Mangel, J.C.; Yañez, I.L.; Seminoff, J.A.Prior to 2007, efforts to monitor and conserve hawksbill turtles (Eretmochelys imbricata) in the eastern Pacific Ocean were opportunistic and records were virtually non-existent. The first abundance estimates were published in 2010, but contained limited data on the species. Ongoing research since that time has led to the identification of several rookeries, including sites containing large proportions of the overall hawksbill nesting currently known to occur in the region. Monitoring projects were established at several sites and have since provided substantial nesting data on the species. Here we summarize data collected between 1983 and March 2016 from all sites (n = 9) confirmed to host >10 nests in any given season to provide an update on hawksbill nesting in the eastern Pacific. We documented a total of 3,508 hawksbill nests, 265,024 hatchlings and 528 individual nesting females in the region. The vast majority of these records (99.4%, 99.9% and 99.6%, respectively) were generated subsequent to 2007, coinciding with the discovery of eight of the nine rookeries included in this study and the organization of monitoring efforts at those sites, which led to the increased documentation conferred here. Our findings should not be misconstrued as increases in actual nesting or signs of recovery, which could diminish the ongoing need for conservation actions, but rather as optimism, that there is still an opportunity to restore the species in the eastern Pacific. The top three sites in terms of average annual number of nests were Estero Padre Ramos (Nicaragua; 213.2 ± 47.6 nests), Bahia de Jiquilisco (El Salvador; 168.5 ± 46.7 nests) and Aserradores (Nicaragua; 100.0 ± 24.0 nests), and all three sites are located in mangrove estuaries in Central America, highlighting the importance of these rookeries/habitats for the survival and recovery of hawksbills in the region. The remaining six sites received between 6.9 ± 7.3 nests (Costa Careyes, Mexico) and 59.3 ± 17.7 nests (Los Cobanos, El Salvador) annually. By integrating data collected on nesting hawksbills with local conservation realities at the most important known hawksbill rookeries in the eastern Pacific, we provide a more holistic view of the conservation status and management needs of the species in this ocean region. © 2017, Escuela de Ciencias del Mar. All rights reserved.Ítem Acceso Abierto Southernmost record of the giant manta ray mobula birostris (Walbaum, 1792) in the eastern pacific(BioMed Central Ltd., 2017) Moreno, B.; Gonzalez-Pestana, A.Background: Manta rays (Mobulidae), Mobula birostris and Mobula alfredi, are widely distributed in tropical and temperate waters. Still, little is known about their movements and their ecological interactions (e.g. behavior and diet). In Peru, M. birostris has only been reported along the northern shore within the Tropical East Pacific Marine Province. No official reports exist from central or south Peru within the Warm Temperate Southeastern Pacific Marine Province. Methods: On December 22nd 2015, a rare sighting of a ~4 m disc width mobulid ray was recorded as video footage near the Palomino Islets, Lima, Peru. Results: In situ observations and subsequent analysis of the footage confirmed that this single mobulid was a M. birostris with a melanistic color morph. Conclusions: This sighting could be explained by the warm El Niño, primary (chl-a), and secondary (zooplankton) productivity events during that same period. This represents the southernmost record of M. birostris in the southeastern Pacific (12°S) and the first report of this species in the Warm Temperate Southeastern Pacific Marine Province and in the Humboldt Current Large Marine Ecosystem. © The Author(s).Ítem Acceso Abierto The effects of land management (grazing intensity) vs. the effects of topography, soil properties, vegetation type, and climate on soil carbon concentration in Southern Patagonia(Academic Press, 2016) Peri, P.L.; Ladd, B.; Lasagno, R.G.; Martínez Pastur, G.Grazing is an economically important activity in Southern Patagonia's steppe and woodland ecosystems. In the past, emphasis has been on maximizing the provisioning capacity of these ecosystems with little concern for the longer term conservation of the ecosystem services related to climate regulation, like carbon sequestration. This is changing rapidly as livestock producers in the region work to develop a certification scheme for sustainable land management for Patagonians rangelands. This study is a scientific contribution towards this broader social objective in which we test whether soil C concentration in topsoil (10 cm depth) can be used as an indicator of rangeland condition. Data on climate, soil chemistry, topography, ecosystem type and stocking rates were obtained from the PEBANPA network of permanent plots database for 145 sites across Southern Patagonia. These variables were used as independent variables in a partial least squares regression in which top soil C was the dependent variable. The effects of land use (stocking rate) on top soil C were barely detectable at the regional scale in Patagonia. Top soil C was however strongly associated with other independent variables, notably soil chemistry and climate variables and also vegetation type. Thus, changes in land use management may not have a significant impact on soil carbon sequestration in these types of ecosystems. This may be because many factors interact to determine top soil C such that the footprint of overgrazing on top soil C is drowned out at the regional scale by other variables. This highlights the need for further work to develop indicators for sustainable land management in the region. © 2016 Elsevier Ltd