Differences in diversity, structure, and variability between intertidal and subtidal meiofaunal assemblages

[EN] Meiofaunal assemblages from intertidal and shallow subtidal seabeds were studied at two sites (one dominated by volcanic sands and the other by organogenic sands) at Tenerife (Canary Islands, NE Atlantic Ocean) throughout an entire year (May 2000?April 2001). Specifically, we aimed (i) to test for differences in diversity, structure, and stability between intertidal and subtidal meiofaunal assemblages, and (ii) to determine if differences in the meiofaunal assemblage structure may be explained by environmental factors (granulometric composition, availability of organic matter, and carbonate content in sediments). A total of 103,763 meiofaunal individuals were collected, including 203 species from 19 taxonomic groups (Acari, Amphipoda, Cnidaria, Copepoda, Echinodermata, Gastrotricha, Isopoda, Insecta, Kinorrhyncha, Misidacea, Nematoda, Nemertini, Oligochaeta, Ostracoda, Polychaeta, Priapulida, Sipuncula, Tanaidacea, and Turbellaria). Nematodes were the most abundant taxonomic group. Species diversity was higher in the subtidal than in the intertidal zone at both sites, as a result of the larger dominance of a few species in the intertidal zone. The meiofaunal assemblage structure was different between tidal levels at both sites, the intertidal presenting greater temporal variability (multivariate dispersion) in the meiofaunal assemblage structure than the subtidal. Sediment grain size, here quantified by the different granulometric fractions, explained the variability in meiofaunal assemblage structure to a greater extent than the percentage of carbonates, a variable linked to sediment origin. This study revealed differences in diversity, assemblage structure, and variability between intertidal and subtidal meiofauna.

Relaciones jerárquicas intra e interespecíficas entre Parablennius parvicornis y Mauligobius maderensis

Se estudia la relación de dominancia entre dos especies de peces (Parablennius parvicornis y Mauligobius maderensis) que conviven en los charcos del intermareal rocoso de las Islas Canarias. Ambas especies mostraron un patrón de jerarquía lineal basado en ataques. Se discute la jerarquía interespecífica y el cambió de rol al enfrentarse individuos de la misma especie e individuos de especies diferentes. Parablennius parvicornis mostró un comportamiento de cooperación intraespecífica y de codominancia frente a Mauligobius maderensis.It is studied the relationship of dominance between two fish species (Mauligobius maderensis and Parablennius parvicornis) which coexist in the same intertidal pools at the rocky shore of the Canary Islands. Both species showed a pattern of linear hierarchy based in attacks. It is discussed the intraspecific hierarchy and variations in the role of individuals when confronted against coespecifics or individuals of a different species. Parablennius parvicornis showed intraspecific cooperation and codominance against Mauligobius maderensis.

Moluscos gasterópodos como bioindicadores en el Archipiélago canario: de procesos naturales a causas antropogénicas

Se han eliminado páginas en blanco

Modelo matemático de los procesos intermareales de acreción y erosión en playas arenosas

In this work, accretion and eros ion processes in intertidal strips of sandy beaches are modelled. With that aim the following steps have been made: 1.- Topographic monitoring of a beach in the Island of Gran Canaria (Spainl. 2.- Development of a mathematical modelo 3.- And interpretation of a significative time serie of records of sedimentary volumes. RESUMEN Se pretende modelizar los procesos de acreción y erosión en franjas intermareales de playas arenosas. Para ello: 1. Se ha hecho el seguimiento de los cambios topográficos de una playa de Gran Canaria (España). 2. Se desarrolla un modelo matemático. 3. y se interpreta una serie temporal de balances sedimentarios

Exploring respiration and respiratory electron transport system (ETS) in Ulva spp.

[ES] Respiration is a key ecological index. For either individuals or communities, it can be use to assess carbon and energy, demand and expenditure as well as carbon flow rates through food webs. When combined with productivity measurements it can establish the level of metabolic balance. When combined with measurements of respiratory capacity, it can indicate physiological state. Here, we report pilot studies the metabolism of the green algae, Ulva rotundata that inhabits intertidal pools of Gran Canaria. As a starting point we used the electron transport system (ETS) to differentiate between different growing conditions in the natural environment. We suspected different levels of stress associated with these conditions and looked for the influence of this stress in the ETS measurements. This technique has been successfully applied to study bacteria, phytoplankton and zooplankton in the ocean, but it has not been used to study sessile marine macroalgae. These neritic and littoral macrophytes have major ecological and industrial importance, yet little is known about their respiratory physiology. Such knowledge would strengthen our understanding of the resources of the coastal ocean and facilitate its development and best use. Here, we modified the ETS methodology for Ulva rotundata. With this modified ETS assay we investigated the capacity of Ulva to resist anoxia. We measured respiration with optodes (Fibox 4, Presens) in the dark to the point of oxygen exhaustion and through 24 h of anoxia. Then we exposed the Ulva to light and followed the oxygen increase due to photosynthesis. We discuss here the capacity of Ulva to survive during anoxia.

Study of environmental radioactivity in Las Canteras beach

[EN]In this final degree work an assessment of the impact of environmental radioactivity, mainly on bathers of the most important beach in Las Palmas de Gran Canaria (Las Canteras), has been done. For this purpose, the main radionuclides contained in intertidal superficial sand samples have been measured by using gamma spectrometry analysis. Also alpha activity of the beach water was determinated by means of ZnS(Ag) scintillation detector. The radioactivity detected was due to the natural occurring radionuclides 226Ra (238U- series), 232Th and 40K in sand samples with an average activity concentrations of 14.6±1.0, 17.4±1.0 and 528±24 Bq/kg, respectively. From these values, the outdoor annual effective dose was of 0.047 mSv/y, which is below to the world’s average value (0.07 mSv/y)