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  • 1
    ISSN: 1432-1939
    Keywords: Nitrate reductase ; Chlorophyll content ; Leaf Specific Area ; Open-forest ; Closed-forest (rainforest)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A study of the sun leaves of two closed-forest (rainforest) and eight open-forest communities in subtropical southeast Queensland, Australia, showed that a large number of pioneer woody species in closed-forests had high levels of nitrate reductase (EC 1.6.6.1), whereas only a few herbaceous species in the open-forests showed high levels. There was a continuously declining gradient in nitrate reductase activity from pioneer to mature-forest species in all communities, associated with a decrease in Leaf Specific Area. The level of nitrate reductase activity was lower in certain plant families (including sclerophyllous monocotyledons, small-leaved composites and legumes), but still showed the same general relationship with Leaf Specific Area. The decrease in Leaf Specific Area is associated with an increase in both the dry weight: fresh weight ratio and the chlorophyll a: chlorophyll b ratio of the leaves. Three groups of plants can be recognised by nitrate reductase activity plotted against water content (% fresh weight) of their leaves-(1) pioneer, (2) mature-forest and (3) semi-sclerophyllous species. As the proportion of cytoplasm to structural tissue (indicated by water content) in leaves increases, there is a continuous increase in (a) nitrate reductase activity (b) total chlorophyll (per unit dry weight) (c) the proportion of chlorophyll b to chlorophyll a and (b) chloroplastic isoform of glutamine synthetase. These attributes are associated with high nitrogen content in the leaves and high photosynthetic potentials, resulting in rapid growth rates of pioneer species.
    Type of Medium: Electronic Resource
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  • 2
    Publication Date: 2021-05-19
    Description: El desarrollo industrial y económico de Colombia se ha expandido en la búsqueda de nuevos recursos minerales hacia los límites del mar territorial. La prospección y construcción de infraestructuras en el mar plantean nuevos retos para el desarrollo sostenible del país. Este estudio de línea base se realizó con el fin de conocer las especies de invertebrados marinos que se han establecido sobre las únicas plataformas permanentes para la explotación de gas ubicadas mar afuera en La Guajira, al norte del Caribe colombiano: plataformas A y B, construidas sobre fondos de 18 y 33 m de profundidad, respectivamente. Por medio de buceo autónomo Scuba, se recolectaron e identificaron 116 especies de invertebrados marinos. Los crustáceos presentaron la mayor riqueza de especies (50 especies), con el infraorden Brachyura como el mejor representado con 10 familias y acumulando 44% de las especies. Los moluscos comprendieron el segundo grupo con 29 especies, seguidos de anélidos con 14, esponjas con 12, cnidarios con 7 y finalmente equinodermos con 4. Los organismos sésiles filtradores dominaron en número de individuos, mientras las formas móviles presentaron un mayor número de especies. Los balanos (Balanus spp.), el octocoral Carijoa riisei y las esponjas fueron los principales constituyentes de la fauna fouling asociada a las estructuras. Aunque no existen estudios previos para el área de estudio ni para el Caribe sur, se considera que la comunidad de invertebrados marinos que ha colonizado las estructuras de las plataformas de gas de La Guajira exhibe una alta riqueza de especies e individuos asociados.
    Description: The industrial and economic development of Colombia has expanded its limits towards the territorial sea in the search for new resources. The prospection and construction of infrastructures in the sea challenge new alternatives for the sustainable development of the country. The main goal of this study was to build a baseline inventory of the marine invertebrates associated to two gas platforms located offshore in La Guajira, at the northeastern Colombian Caribbean Sea: platforms A and B, sitting on sandy bottoms at 18 and 33 m depth, respectively. This inventory includes a total of 116 species of marine invertebrates that were collected by Scuba diving. Crustaceans had the greatest richness with 50 species, from which the infraorder Brachyura was the best represented with 10 families including approximately 44% of species. Mollusks comprised the second largest group with 29 species, followed by annelids with 14 species, sponges with 12 species, cnidarians with 7 species, and finally echinoderms with 4 species. Filter-feeding and sessile organisms dominated in abundance, while mobile species showed a larger number of species. The barnacles complex ( Balanus spp.), the octocoral Carijoa riisei and sponges were the main components of the fouling fauna on the structures. Although there are no previous studies for the study area and the southern Caribbean, it is considered that the invertebrates community associated to gas platforms in La Guajira exhibit both high species richness and a large abundance of organisms
    Description: Published
    Keywords: Artificial substrates ; Biofouling ; Macrofauna ; Inventory of species ; ASFA15::A::Artificial substrata ; ASFA15::I::Inventories
    Repository Name: AquaDocs
    Type: Journal Contribution , Refereed
    Format: pp.361-386
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