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La Paz, Mexico

Maya Y.,CIBNOR
Tropical and Subtropical Agroecosystems | Year: 2011

Soil degradation due to water erosion is a serious threat to the quality of resources upon which man depends for his subsistence, such as water and land. The assessment of soils based on environmental variables has become essential for planning and setting soil management to improve soil quality. This paper reviews the advances of technology to asses the degradation caused by water erosion at different scales, considering the factors that are determinant at each level. Analyzed scales are: surface soil aggregates, agricultural plot or rangelands, and watershed. In each case, the mentioned erosion variables are discussed, as well as the methods and more common tools used for evaluation. A study case is presented. Source


Arizmendi-Rodriguez D.I.,Avenida Institute Polytechnic Nacional s n Col | Cruz-Escalona V.H.,Avenida Institute Polytechnic Nacional s n Col | Quinonez-Velazquez C.,Avenida Institute Polytechnic Nacional s n Col | Salinas-Zavala C.A.,CIBNOR
Journal of Fisheries and Aquatic Science | Year: 2011

The feeding habits of the Panama brief squid, Lolliguncula panamensis (Berry, 1911), it inhabits off Peru until Gulf of California, was determined by examining the stomach contents of 657. Panama brief squid were collected from the incidental catch of shrimp trawling fishery during 2003-2006 and 2008, along the Gulf of California, Mexico. Most of the stomachs were empty and those that contained food presented highly digested prey items. Eight taxa were identified in the stomach contents and the index of relative importance indicated to juvenile of Pacific sardine (Sardinops sagax), the most important prey, this prey bring 99.6% IRI. Results suggest that L. panamensis is a highly opportunistic predator foraged primarily in coastal and epipelagic waters, whose diet reflect the local abundance of potential prey species, mainly small pelagic fishes. © 2011 Academic Journals Inc. Source


Rose K.A.,Louisiana State University | Fiechter J.,University of California at Santa Cruz | Curchitser E.N.,Rutgers University | Hedstrom K.,University of Alaska Fairbanks | And 13 more authors.
Progress in Oceanography | Year: 2015

We describe and document an end-to-end model of anchovy and sardine population dynamics in the California Current as a proof of principle that such coupled models can be developed and implemented. The end-to-end model is 3-dimensional, time-varying, and multispecies, and consists of four coupled submodels: hydrodynamics, Eulerian nutrient-phytoplankton-zooplankton (NPZ), an individual-based full life cycle anchovy and sardine submodel, and an agent-based fishing fleet submodel. A predator roughly mimicking albacore was included as individuals that consumed anchovy and sardine. All submodels were coded within the ROMS open-source community model, and used the same resolution spatial grid and were all solved simultaneously to allow for possible feedbacks among the submodels. We used a super-individual approach and solved the coupled models on a distributed memory parallel computer, both of which created challenging but resolvable bookkeeping challenges. The anchovy and sardine growth, mortality, reproduction, and movement, and the fishing fleet submodel, were each calibrated using simplified grids before being inserted into the full end-to-end model. An historical simulation of 1959-2008 was performed, and the latter 45. years analyzed. Sea surface height (SSH) and sea surface temperature (SST) for the historical simulation showed strong horizontal gradients and multi-year scale temporal oscillations related to various climate indices (PDO, NPGO), and both showed responses to ENSO variability. Simulated total phytoplankton was lower during strong El Nino events and higher for the strong 1999 La Nina event. The three zooplankton groups generally corresponded to the spatial and temporal variation in simulated total phytoplankton. Simulated biomasses of anchovy and sardine were within the historical range of observed biomasses but predicted biomasses showed much less inter-annual variation. Anomalies of annual biomasses of anchovy and sardine showed a switch in the mid-1990s from anchovy to sardine dominance. Simulated averaged weights- and lengths-at-age did not vary much across decades, and movement patterns showed anchovy located close to the coast while sardine were more dispersed and farther offshore. Albacore predation on anchovy and sardine was concentrated near the coast in two pockets near the Monterey Bay area and equatorward of Cape Mendocino. Predation mortality from fishing boats was concentrated where sardine age-1 and older individuals were located close to one of the five ports. We demonstrated that it is feasible to perform multi-decadal simulations of a fully-coupled end-to-end model, and that this can be done for a model that follows individual fish and boats on the same 3-dimensional grid as the hydrodynamics. Our focus here was on proof of principle and our results showed that we solved the major technical, bookkeeping, and computational issues. We discuss the next steps to increase computational speed and to include important biological differences between anchovy and sardine. In a companion paper (Fiechter et al., 2015), we further analyze the historical simulation in the context of the various hypotheses that have been proposed to explain the sardine and anchovy cycles. © 2015 Elsevier Ltd. Source


Trujillo A.G.,Autonomous University of Chihuahua | Trujillo A.G.,Autonomous University of Baja California Sur | Espinosa A.P.,Autonomous University of Zacatecas | Salgado S.Z.,UABCS.Carretera Al sur | And 6 more authors.
Interciencia | Year: 2016

Cowpea (V. Unguiculata (L.) Walp) is consumed as human food and animal feed in many countries; in Mexico it is also used as green manure to improve soils. The study was conducted in La Paz, Baja California Sur, Mexico to determine if there is an intraspecific competition in V. Unguiculata and its effect on productive characteristics of the crop under field conditions. Three treatments consisting in placing 1, 2 and 3 seeds every 25cm in rows 15m long separated by 70cm, with 5 replicates, were compared. The following variables were evaluated: stem diameter, stem length, number of leaves, number of pods, forage weight and number of secondary stems. A multivariate analysis of variance was performed to explore the correlation between these variables. The performance of the studied variables decreased (P>0.001) as plant density of seeds increased. It is concluded that V. Unguiculata u nder fi eld c onditions p resents i ntraspecific competition with regard to the variables studied here. Source


Mucino-Marquez R.E.,Metropolitan Autonomous University | Garate-Lizarraga I.,CICIMAR IPN | Lopez-Cortes D.J.,CIBNOR
Acta Biologica Colombiana | Year: 2015

The genus Prorocentrum Ehrenberg includes 81 marine species, of which 21 are considered causative agents of harmful algal blooms, and approximately 9 species produce toxins. The objectives of this study were to determine distribution and abundance of Prorocentrum species during an annual cycle at two sampling sites within tuna farms near San Juan de La Costa (SC), Rancheros del Mar (RM) and at a station without the influence of these farms located off El Mogote (M), in the Bahia de la Paz, Gulf of California. Samples were taken monthly (June 2006-May 2007) at different depths at SC (0.25 and 50 m), at the RM (0.15 and 30 m) and at El Mogote (0 m) with a van Dorn bottle. The results showed a total of twelve species in the annual cycle: P. compressum, P. dactylus, P. emarginatum, P. gracile, P. lima, P. micans, P. minimum, P. rhathymum, P. rostratum, P. shikokuense, P. triestinum and P. vaginula, of which the first eight form blooms. The study of Prorocentrum blooms became important because they have been linked to widespread harmful ecosystem impacts. © 2015, Universidad Nacional de Colombia. All rights reserved. Source

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