Effects of preservatives on stable isotope analyses of four marine species (Estuarine, Coastal and Shelf Science)

11/03/09 ,

Carabel C, P Verísimo & J Freire (2009). Effects of preservatives on stable isotope analyses of four marine species. Estuarine, Coastal and Shelf Science 82:348-350. (pdf)

Abstract

The aim of the present study is to quantify the effect of formalin–ethanol preservation on the carbon and nitrogen stable isotope signatures of four taxonomical groups of marine species (Himanthalia elongata, Anemonia sulcata, Mytilus galloprovincialis and Patella vulgata). To examine temporal changes in the effects of preservation and to determine if preservation induced predictable shifts in ?13C and ?15N signatures, repeated analyses were carried out after 6, 12 and 24 months of preservation. Data from our study showed highly variable effects of the formalin–ethanol preservation on carbon and nitrogen isotope signatures between species. The use of a general correction factor was not possible, or else it should be species-specific. Differences in nitrogen isotopic values between preserved and unpreserved samples were minor compared to the assumed enrichment between trophic levels. The combined use of data from preserved and unpreserved samples could lead to biases in the estimation of the trophic level of organisms. Changes that preservatives caused in carbon values were variable between species and not always small enough to be ignored. So the use of data from preserved samples could change the interpretation of the mixing models used to determine the importance of multiple sources of carbon. In order to elucidate the effects that preservatives have in other species, further studies will be necessary.

Groundfish species associations with distinct oceanographic habitats in the Northern California Current

15/02/09 ,

Juan-Jorda, MJ, Barth, JA, Clarke, ME and Wakefield, WW, 2009. Groundfish species associations with distinct oceanographic habitats in the Northern California Current. Fisheries Oceanography, doi:10.1111/j.1365-2419.2008.00489.x

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MARIA JOSE JUAN-JORDA 1*, JOHN A. BARTH 1, M. E. CLARKE2 AND W. W. WAKEFIELD3

1College of Oceanic and Atmospheric Sciences, Oregon State University, 104 COAS Admin Bldg, Corvallis, OR 97331-5503, USA

2National Oceanic and Atmospheric Administration, Northwest Fisheries Science Center, 2725 Montlake Blvd. East, Seattle, WA 98112-2097, USA

3National Oceanic and Atmospheric Administration, Northwest Fisheries Science Center, 2032 SE OSU Drive Newport, OR 97365, USA

*Present address: M. J. Juan-Jorda´, Recursos Marinos y Pesquer?as, Facultad de Ciencias, Universidad de A Coruna, Alejandro de la Sota 1, 15008, A Corun˜ a, Spain

ABSTRACT

Ecosystem-based management places a strong emphasis on habitat, but little work has been done to examine how water column properties may influence the distribution, abundances and structure of groundfish assemblages. We identified and described oceanographic habitats in the northern California Current based on temperature, salinity, chlorophyll-a and the inherent variability in these factors. We then examined the distribution and the abundance of groundfishes in relation to these oceanographic habitats and conditions with the long-term goal of improving science for ecosystem-based management of the groundfish fishery of the west coast of the USA. Five summertime oceanographic habitats with distinct physical and biological characteristics were identified in the northeast Pacific Ocean off the northwest Coast of the USA: Offshore Habitat, Upwelling Habitat,majority of the associations were weak due to overlap of species distributions in the nearshore oceanographic habitats. In contrast, groundfish species showed strong associations with individual oceanographic factors, primarily depth, surface chlorophyll-a, and bottom salinity and temperature. In addition, latitudinal variations in upwelling intensity, river discharge and productivity led to the identification of three regions where high chlorophyll-a concentrations were associated with large abundances of specific groundfish species. The combined oceanographic datasets and data products that we produced have the potential to be a powerful tool for improving our knowledge of the west coast ecosystem.

Patterns of juvenile habitat use by the spider crab Maja brachydactyla as revealed by stable isotope analyses (Scientia Marina)

26/11/08 ,
Freire J., S. Carabel, P. Verísimo, C. Bernárdez & L. Fernández (2009). Patterns of juvenile habitat use by the spider crab Maja brachydactyla as revealed by stable isotope analyses. Scientia Marina 73(1): 39-49. PDF PDF (466KB)
Abstract:
Patterns of habitat use by spider crab juveniles, Maja brachydactyla, from two geographic areas on the NW coast of the Iberian Peninsula were studied through the analysis of carbon and nitrogen stable isotope relations in muscle and hepatopancreas. Main potential preys of spider crab juveniles in rocky and sandy habitats and different organic matter sources in coastal food webs were also analysed. Isotopic ratios showed no difference between rocky and sandy habitats. The use of carapace colour and epibiosis as an indicator of habitat use was not supported by our data. These results suggest that movements between the two habitats are much more frequent than suggested in previous studies. In the coastal food web, two main trophic compartments were identified according to their organic matter source: one based on plankton and seaweeds (rocky habitats), and one based on sedimentary particulate organic matter (sandy bottoms). By means of the model of Phillips and Gregg (2003), it was found that juveniles of Maja brachydactyla from both habitats consumed approximately two thirds of the preys in rocky habitats and one third in sedimentary habitats. The results indicate that in exposed environments large juveniles spend most of the time on sedimentary bottoms, where they find more refuge, moving frequently to nearby rocky substrates to feed.

Redes sociales: ¿modelos organizativos o servicios digitales? (El Profesional de la Información)

18/11/08 ,
Freire, J. (2008). Redes sociales: ¿modelos organizativos o servicios digitales? El Profesional de la Información. Volumen 17, número 6 (Redes sociales), pp. 585-589
PDF PDF (377KB)
Resumen:

Somos seres sociales y formamos redes desde nuestros inicios evolutivos. La red constituye un nuevo paradigma social y económico que ha sido denominado “Sociedad Red”. Las personas que usan intensivamente las herramientas digitales fragmentan su identidad y la integran en múltiples redes locales y globales. Los servicios de redes sociales constituyen una simplificación y restricción de la diversidad de interacciones sociales. La combinación “a medida” de herramientas de la web 2.0 parece más interesante que el modelo Facebook.

Title: Social networks: organizational models or digital services?

Abstract: We are social beings and we have been creating networks since our inception. The network represents a new paradigm for social and economic development that has been called the “Network Society”. People who use digital tools intensively are fragmenting their identity into multiple local and global networks. The social network services are a simplification and a restriction of the variety of social interactions. The combination of various Web 2.0 tools seems more interesting than the Facebook model.

How to assign a catch value to fishing grounds when fisheries statistics are not spatially explicit. Scientia Marina

22/10/08 ,
Pita P., J. Freire & A. García-Allut (2008). How to assign a catch value to fishing grounds when fisheries statistics are not spatially explicit. Contents of this volume. Scientia Marina 72(4): 693-69
Abstract: Fishery statistics do not usually include small-scale spatial references to assess the effects of natural or human disturbances. We present a methodology which assigns a geographical origin to the catches and assesses the total revenue of the fishing grounds. Market statistics are combined with the results of an ethnographic survey to provide a spatial allocation of the fishing effort. In the present case study, which corresponds to the Galician coast (NW Spain), 253 vessels from 14 base ports that fish in 80 fishing grounds were identified. The annual total revenue of the catches was 8.28 M€ and ranged from a minimum of 4928 € to a maximum of 0.60 M€ with a mean value per fishing ground of 0.104 M€.
PDF PDF (313KB)

Universities and Web 2.0: Institutional challenges (eLearning Papers 8)

30/04/08 ,
Freire, Juan (2008). Universities and Web 2.0: Institutional challenges. eLearning Papers Nº 8. ISSN: 1887-1542. www.elearningpapers.eu PDF PDF (94KB)

La revista electrónica eLearning Papers acaba de publicar su número 8 con un monográfico titulado Openness and learning in today’s world (español, inglés) dedicdo al análisis de de los paradigmas abiertos favorecidos por las tecnologías de la información, entre otras la web 2.0, en el aprendizaje.

Edita esta revista elearningeuropa.info, el portal de la Comisión Europea para la promoción de las tecnologías de la información en el “lifelong learning”. La publicación es multilingue (al menos en los resúmenes de los artículos) y utiliza una licencia Creative Commons.

En este número de eLearning Papers se publican los siguientes artículos:

Mi artículo Universities and Web 2.0: Institutional challenges (disponible en pdf aquí y aquí) es una versión revisada y actualizada de la conferencia que presenté en el Fourth International Seminar. Web 2.0 and education de la Universitat Oberta de Catalunya UNESCO Chair in eLearning (Barcelona 17–19 Octubre 2007). Una versión previa en español (Los retos y oportunidades de la web 2.0 para las universidades; pdf) se publicó en La Gran Guía de los Blogs 2008 de la Colección Planta29. Este es el resumen de mi artículo:

Freire, Juan (2008). Universities and Web 2.0: Institutional challenges. eLearning Papers Nº 8. ISSN: 1887-1542. www.elearningpapers.eu

The irruption of the Web 2.0 internet in universities does not modify only learning models – organizative models are also challenged, creating important fears among the managers of the institutions. Teachers, researchers and students started some years ago to use social software tools, but in few cases these experiences have allowed any scaling from the individual to the institutional level.

The promises and potential of web 2.0 in universities need an adequate strategy for their development which has to confront the bottlenecks and fears common in these institutions, which could explain the lack of adaptation. Some of the bottlenecks highlighted in this paper are: a) the rejection by the users, personnel and students, b) the lack of an incentive system, c) the available pre-web 2.0 technology, and d) universities show in some cases a culture of aversion to innovation and entrepreneurship.

The adoption of a Web 2.0 approach to learning in universities is a complex process confronting important technological, managerial and human barriers. For these reasons, the design of a set of objectives and a strategy accepted and promoted by the managers, especially those in charge of knowledge management, is absolutely needed. This first step requires in many cases radical cultural changes for people used to work and make decisions in a different scenario.

The introduction for the web 2.0 approach to learning in universities must be done through an adaptive strategy, one that may be designed integrating previous experiences of educational, research and business organizations.

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