FLORA IF LAKES

Author: TROBAJO PUJADAS M. ROSA.
Year: 2003.
University: GIRONA.
Place of defense: CIENCIAS.

Author: VENTURA OLLER MARC.
Year: 2004.
University: BARCELONA.
Place of defense: FACULTAD DE BIOLOGÍA.
Place of preparation: UNIVERSITAT DE BARCELONA.

Summary: The aim of the thesis was to describe the variability in the life histories of the crustacean zooplankton community of I'Estanh Redon, with a special emphasis on the descriptions of their life cycles, and their ecological characteristics predation. The end of the period covered ice was the key parameter to characterize the seasonal life cycles in the three species, the copepod calanoide Diaptomus cyaneus, copepod ciclopoide Cyclops abyssorum and cladócero daphnia pulicaria. Comparing him estequiométrica composition of the three species with the seston Daphnia had revealed that a higher proportion of phosphorus that seston, and the two copepods content higher in carbon and nitrogen and daphnia seston. It is suggested that daphnia was limited by the availability of phosphorus. The abundance of Daphnia estava negatively correlated with the biomass of Cyclops, suggesting that the possible predatory, Cyclops in Daphnia may also be a relevant factor. Reproduction was the main cause of variation in the elemental content of the three species, while there was no connection with the growth. The females of all three species have lost between 32 and 48% of the content of carbon and hydrogen during playback, with a corresponding decrease in lipid and carbohydrate content. The nitrogen content was constant as well as its share of proteins and chitin. Daphnia and Diaptomus lost respectively 35 and 56% of its initial content of phosphorus during playback, while the phosphorus content of Cyclops not changed. It is suggested that the observed variability in the elemental composition of these species is generally for all species with decoupled reproduction of food. Differences ínter-específicas in the amino acid composition were three times greater than those intra-específicas. The two copepods were more similar composition among them than with cladócero regardless of the seasonal changes and ontogénicos. The three species had different isotopic signals. The two copepods were a trophic level above cladocero. During growth, the contents of o13 and o15N of daphnia increased enriched a signal to a signal more impoverished. The copepoditos of Cyclops also showed a progressive increase in its isotopic signal, which differed by o13e and o15N. Fractionation of nitrogen between Cyclops and daphnia was directly related to the amino acid distance between the two species, suggesting that Cyclops had a limiting amino acid.

Author: BUCHACA ESTANY TERESA.
Year: 2004.
University: BARCELONA.
Place of defense: FACULTAD DE BIOLOGÍA.
Place of preparation: FACULTAD DE BIOLOGÍA.

Summary: The overall aim of the thesis was to study the signal indicators in different compartments pigments of high mountain lakes in the Pyrenees (water column, sediment surface sedimentary record i) to consider the value of pigments as markers and indicators of taxonomic processes occurring in different time scales. To see the effect on the local signal pigments changes in factors such as irradiance regime or the mixture, a study was conducted at seasonally in the lake Redon. The ratios of a particular group marker pigment algal and biovolume algal corresponding group were continuing in the area fótica the lake for most of pigments and algal groups. However, the ratio violaxantina-biovolumen of crisófitos increased in inverse proportion to the depth of the sample. We used the program CHEMTAX to estimate the composition of algal groups and compare with results obtained from biovolume estimated using a microscope. More than 80 lakes in the Pyrenees were sampled in different compartments. The crisófitos were the group algal dominated in the deep chlorophyll maximum in a larger number of lakes. The gradient most important groups in the distribution of kelp along the Pyrenees was defined by the trophic status of the lakes. The criptófitos appeared associated with lakes with higher concentrations of phosphorus, and the presence of fish while the crisófitos dominated the opposite end of the gradient at the trophic status. The clorófitos were correlated with a greater abundance of macrozoopláncton. A second gradient was correlated with the concentration of calcium. In the sediment the ratio of aloxantina (signal planktonic) and diatoxantina (signal benthic) was a good indicator of the relative contribution of these two environments primary production system. The factors with the greatest influence on the preservation of chlorophyll were pH and the characteristics of the vegetation of the basin. The pigments indicators of the presence of photosynthetic sulfur bacteria were mainly in lakes with relatively little deep basins and large forested. Finally, we rebuilt the primary production of the lake Redon along the Holocene. The signal production in early Holocene had a predominant source benthic, while during the last 1500 years was mainly planktonic. Until the end of the half Holocene variability in primary production could be attributed to changes in the internal and external loading of phosphorus associated with changes in climate. Since 1500 a. BP variability could be attributed mainly to changes in the burden of external phosphorus-related disturbances on the floor of the basin.

Author: BERNAL BERENGUER SUSANA.
Year: 2005.
University: BARCELONA.
Place of defense: FACULTAD DE BIOLOGÍA.
Place of preparation: UNIVERSIDAD DE BARCELONA.

Author: Badosa Salvador Anna.
Year: 2006.
University: GIRONA.
Place of defense: Institut d'Ecologia Aquàtica.
Place of preparation: Universitat de Girona.

Summary: Between 1999 and 2003 was a project of Life in the marsh restoration of halophytic The Pletera and freshwater lagoon Ter Vell (Baix Ter wetlands, NE Iberian Peninsula). This thesis aims to establish the operation of both ecosystems, analyze their environmental problems and to assess the effects of the restoration. The marsh The Pletera had been affected by a zoning plan, and consequently changed their hydrology and several lagoons and wetlands disappeared. The creation of new shelters for gaps as a fish threatened, Aphanius iberus, and the population of these shelters were the main actions of restoration. It discussed the role of hydrology in the composition and dynamics of nutrients and zooplankton in five permanent gaps, including new. They all hydrology was determined by a long period of confinement without tickets water, irregularly interrupted by sudden floods (temporary sea and precipitation). The dynamics of inorganic nitrogen depended on the inflow of water, while the phosphorus, total nitrogen and organic matter was related to the process of accumulation and internal recycling during confinement. The former gaps showed a higher content of nutrients and organic matter, suggesting a successive accumulation of these elements during periods of confinement over the years. The zooplankton community integrates the effects of the two factors, hydrology and the age of the lagoon, since the first time determines your employer and the second explains the differences in the composition and structure between the old and new loopholes. The structure of the community was analyzed through a combination of approaches using taxonomic and sizes respectively, an index of taxonomic diversity and a variety of sizes. Both indices had different responses to different environmental factors. The range of sizes was related to the trophic interactions (predation and competition) while taxonomic diversity was more sensitive to abiotic factors (nutrients). The features and Limnological communities macrophytes and invertebrates new gaps were similar to those of the natural habitat of A. Iberus in the marshes (former lagoon). The rapid growth of the new population of A. Iberus suggested that the new habitat provided a refuge favorable to this species, at least in the short term. The gap Ter Vell is a eutrophic lake that in recent decades has been fueled mainly by the surplus water for irrigation. The restoration actions focused on the improvement of water quality through (1) the reduction of nutrient inputs through some wetlands constructed, and (2) of the dredged sediment to reduce the organic content. Parallel to the restoration, but independently, managing agricultural water changed the irrigation system and drastically reduced the flow of fresh water input. There was therefore a change in the hydrological regime. We examined the short-term effects of this change on the characteristics and Limnological zooplankton of the lagoon. Before the change, hydrology was artificial because the period of flooding freshwater had been prolonged because of agricultural demand. The gap presented a character exorreico with a high rate of renewal of the water. After the change, hydrology was more dependent on the weather and the lagoon presenting a more endorreico, with fewer entrances and water for long periods of confinement. The composition and dynamics of nutrients tended to look like that of the gaps in the marsh. Tickets decreased nutrient and organic matter and increased salinity due to the recycling processes and internal accumulation became more relevant. The zooplankton not tended to look like that of the gaps in the marsh, at least in the short term. To comply with the DMA, all proceedings in an ecosystem 8 should 4a3 protect and even improve their ecological status. It analyzed the short-term effects of hydrological change on the ecological state of Ter Vell. We applied various indicators to determine the ecological status before and after the change. Some results offered doubts about this gap in the use of indicators developed for ecosystem functioning with a very different nature. However, those most appropriate indicators suggested an improvement in the ecological status of Ter Vell after hydrologic change.

Author: BLANCO LANZA SAÚL.
Year: 2006.
University: LEÓN.
Place of defense: FAC. DE CIENCIAS BIOLÓGICAS Y AMBIENTALES..
Place of preparation: FACULTAD DE CIENCIAS BIOLÓGICAS Y AMBIENTALES.

Summary: This work is based on five research papers on different aspects of ecology trophic of fish in several lakes Brief. It has been experimentally studied ecology trophic of Chondrostoma arcasii, a species endemic to the Iberian Peninsula, and also the species introduced Gambusia holbrooki, through experiments bifactoriales in mesocosmos conducted in two lakes someros with different concentrations of nutrients and population densities of fish. The results show that C. Arcasii, turbidity of the water remained high in treatments with fish, but it dropped in the mesocosmos with high concentrations of nutrients due to the proliferation of cladocerans populations. This species exhibited a diet generalist with a significant contribution from non planktonic components. It also noted a change dietary ontogénico towards bento-detritivorismo. The proportion of zooplankton in the digestive contents increased with nutrient inputs. C. Arcasii selected the cladóceros on copepods and rotifers. Some mesocosmos with fish showed transparency of the water, probably due to physiological changes associated with high concentrations of ammonium. For G. Holbrooki, the results confirmed that this is a kind planctívora and omnivora incorporated into your diet also algae and detritus. The addition of nutrients caused virtually no changes in dietary habits of this species, but an increase in the population density of individuals brought a change detritivorismo towards zooplanctivorismo. In the presence of submerged macrophytes, predation focused on zooplankton and the plankton associated with the plants in his absence increased predation on benthic macroinvertebrates. Females depredaron above type of prey, including detritus. The diet of males and juveniles are not solapó, the first being the more selective about ostracods, while juveniles consumed preferably detritus, rotifers and cladocerans. It also investigated the communities of fish and trophic interactions someros some lakes and coastal Mediterranean. We examined the stomach contents of the fish to determine patterns of food each species and their influence on food chains lake. The omnivores dominated in general, regardless of trophic status of the lake and hardly piscívoras species were observed. We found differences between lakes and between communities of dams available. The maximum biomass and diversity of fish was observed in the lake of the Lagoon of Valencia, where he dominated the mugílidos and C. Carpio. The other lakes presented populations young Atherina boyeri and Liza ramado, endemic species (Barbus guiraonis, Aphanius iberus) and intruducidas (Lepomis gibbosus, Micropterus salmoides, Gambusia holbrooki). The fish were mainly detritívoros, turning to zooplanctivorismo depending on the abundance of macrozooplankton. Demographic changes and diet optional fish communities influenced the food web of lakes through predation and recycling of nutrients (excretion and sediment bioturbation). For Lake of the Lagoon of Valencia, a thorough historical review of existing data on its fish fauna, as well as their fishing records. The results show a significant reduction in species richness, especially from the years 1950, a large increase in the populations of exotic species of fish and an increase in the populations of mugílidos. This trend is consistent with the accused eutrophication of the lake, the disappearance of macrophytes s 8 umergido b54 s overfishing of certain species in times past. There were seasonal cycles in the specific composition of the catch, which relates to the population dynamics of each species and to the handling of the hydrological cycle of the lake to grow rice. The top commercial catch took place between October and January, which reduced the predatory fish on macrozooplankton and increased transparency of the water, taking other implications for the lake's food web. Finally, we studied the experimental results concerning the effects of different densities of fish (Ch. arcasii) and nutrients on the growth of epifiton a cursory lake (Lake Sentiz, Leon). The addition of nutrients resulted in a dramatic decline in the total biovolume of epifiton, and specifically in the bacilariofíceas and zignematofíceas, increasing the number of cyanobacteria. The presence of fish increased the abundance of algal all groups, except for cyanobacteria. The different response of the different groups in kelp treatments highest nutrient is attributed to their special ecofisiológicas and resistance to the concentration of ammonium. The fish had no clear effect on the abundance of macroinvertebrates associated with the plants and on the growth of epifiton. Indirect effects of the fish seem to be one of the main causes that influenced algal growth in the mesocosmos with fish. There was a decline in the macrophytes and epifiton as increased nutrients as a result of increased phytoplankton In conclusion, the role of the direct and indirect effects of fish and fish diet highlighted as key factors in understanding the causes that control growth epifiton and structure of the food web in lakes someros studied. Fish affected biodiversity, water quality and transparency. Strategies for the recovery of eutrophic lakes someros should include both controlling the entry of nutrients as their communities of fish, reinforcing appropriate actions for the management and conservation of these and aquatic plants.