Relació entre grandària i nombre d'ous en un copèpode d'aigua dolça

Both in poikylotherms and in homeotherms there is a clear relationship between the animal's body size and the number of eggs laid. Not only the egg number, but the individual egg size varies; usually, there is an inverse relation between them. In a sense, the variation being more accused in the number than in the size can be thought as an expression of oppossed evolutionary strategies or trends. This study is intended to show the real relationship between the egg number and size and the individual size in the freshwater copepod Tropocyclops prasinus from Spanish dams. The copepods from northern water masses have a greater egg number than those from southern impoundments. The allometric relation between body size and egg number nears 3, but if the volume of an oviger sac germ mass is considered the relation is more clear-cut. Egg size varies less than egg number; when the copepod size increases the egg number also increases, not its size. That is to say, the metabolism of the somatic and germ cells is differently influenced by the environmental conditions

Stephos marga/efi sp. nov. (Cope poda: Calanoida) from a submarine cave of Majorca Island (Western Mediterranean)

Stephos margalefi sp. nov. is described as a new species from a submarine cave of Majorca (Balearic Islands). The main diagnostic character is the structure of the fifth legs in both sexes, which distinguish it of the 19 earlier known species of the genus Stephos

Planktonic gradients along a Mediterranean sea cave

The existence of gradients in the composition of planktonic cornmunities through a 50 m long submarine cave of the Medes Islands (NW Mediterranean) has been verified. In spite of an active water exchange (previously evaluated tumover ranges between 12 and 24 hours), strong gradients, persisting throughout all year, were found in both phyto- and zooplanktonic fractions. Numbers of both individuals and taxa of diatoms, dinotlagellates, copepods, and meroplanktonic stages of benthic invertebrates decrease steeply from the entrance of the cave to the inner parts, thus producing an almost total absence of plankton at the end of the cave. On the other hand, benthic diatoms, fungi and spirorbida - all benthic groups accidentally sampled - neither decrease nor even increase to the inner stations, which suggests a tolerance to the "cave effect". These results are so clear-cut that by themselves they can explain the puzzling decay of suspension-feeders among the benthic fauna from the inner parts of submarine caves in two ways : i) scarcity of benthic larvae for settlement, and ii) scarcity of phytoand zooplankton for food

Leaf-litter decomposition in headwater stream: a comparation on the process among four climatic regions

The main purpose of our work was to elucidate factors responsible for the geographical differences in leaf-litter decomposition rates in Spanish oligotrophic headwater streams. Decomposition experiments with alder (Alnus glutinosa) leaf litter were carried out in 22 headwater streams in 4 different climatic regions across the Iberian Peninsula (Cornisa Canta´brica, Cordillera Litoral Catalana, Sierra de Guadarrama, and Sierra Nevada). Streams that were similar in size, flowed mainly over siliceous substrate in catchments with scarce human settlements and activities, and fell within a range of low nutrient concentrations were chosen in each region. Breakdown rates were regionally variable and were low (0.109–0.198% ash-free dry mass [AFDM]/degree day [dd]) in the Cornisa Canta´brica, the most mesic and Atlantic region, and high (0.302–0.639% AFDM/dd) in Sierra de Guadarrama, one of the coldest and most inland areas. Temperature was not the determining factor affecting differences in breakdown rates among regions, and breakdown rates were not related to concentrations of dissolved nutrients. However, microbial reproductive activity (sporulation rates) was significantly correlated with dissolved P concentration. Breakdown rates were explained better by presence and feeding activities of detritivores than by decomposer activity. Incorporation of breakdown rates in assessment schemes of stream ecological status will be difficult because leaf processing does not respond unequivocally to environmental factors when climatic regions are considered. Thus, regional adjustments of baseline standards in reference conditions will be required

Relació entre grandària i nombre d'ous en un copèpode d'aigua dolça

Both in poikylotherms and in homeotherms there is a clear relationship between the animal's body size and the number of eggs laid. Not only the egg number, but the individual egg size varies; usually, there is an inverse relation between them. In a sense, the variation being more accused in the number than in the size can be thought as an expression of oppossed evolutionary strategies or trends. This study is intended to show the real relationship between the egg number and size and the individual size in the freshwater copepod Tropocyclops prasinus from Spanish dams. The copepods from northern water masses have a greater egg number than those from southern impoundments. The allometric relation between body size and egg number nears 3, but if the volume of an oviger sac germ mass is considered the relation is more clear-cut. Egg size varies less than egg number; when the copepod size increases the egg number also increases, not its size. That is to say, the metabolism of the somatic and germ cells is differently influenced by the environmental conditions

Morphological differentiation in the copepod Tropocyclops prasinus

Primer Congreso Español de Limnología, celebrado del 4 al 7 de diciembre de 1981 en Barcelona.-- 12 pages, 5 figures, 2 tables, 1 appendix[EN] Populations of Tropocyclops prasinus (Copepoda Ciclopidae) of different origins present a marked morphological variability. To analize this variability, sets of fifty individuals were obtained in two seasons of the year from 15 reservoirs scattered all over Spain. [...][ES] La morfología de los individuos de una especie presenta variacioens que se ponen de manifiesto cuando se compara individuos de una misma edad de poblaciones diferentes. La variación de las dimensiones de los organismos, puede ser debida tanto a la influencia directa del ambiente como al resultado de la selección de combinaciones genétivas (Margalef, 1955). [...]Peer reviewe

Surface plankton of the Balear sea in July 1966

22 pages, 4 figures, 8 tables[EN] Twelve stations have been occuped (fig. 1) and in each station following information has been obtained: thermic profiles, Secchi disc readings, samples of surface water for phytoplankton analisis, and net tows for pelagic zooplankton. [...][ES] Se creyó interesante aprovechar un crucero de vacaciones en el Mar Balear, a fordo de la embarcación de recreo "Bon Temps", para recoger datos hidrográficos y muestras de plancton de aquella zona. [...]Peer reviewe

Dimensions and allometry in Tropocyclops prasinus. Empirical relationships with environmental temperature

5 pages, 2 figures, 1 tableFor a particular species, the comparison of individuals of the same age belonging to different populations shows the existence of a morphological variability that can be due to direct environmental effects or may be the expression of different genetic combinations. [...]Peer reviewe