Fish ecology in Lake Banyoles (NE Spain): a tribute to / Elena Roget, Xavier Casamitjana, J. Pararols
Roget i Armengol, Elena


En: Limnetica, núm. 7 (1991) , p. 23-36

Wind induced phenomena as the set-up of the therrnocline and the consequent interna1 seiches have been recorded in the southern lobe of Banyoles Lake. The observed period is in agreement with that obtained theoretically by the MortimerIDefant method. During these events -about two days- the thermocline migrated more than two meters. The Richardson number during this period "f seiches suggests that the induced shear was not the force but the direct effect of the wind. From November to April a bottom baroclinic current from north to south was also recordered. The differential heating between the two lobes is due to their significantly different depth and to the different incoming heat flux through the underground sources. This current can be observed indirectly from temperature data but also directly from the data recordered in a currentmeter too. The current is highly influenced by the wind blowing in the northsouth direction. In the central part of the lake, currents up to 12 cmls are observed. Their path, slightly inflected towards the right, seerns to be influenced by the bottom of the lake, but Coriolis force may be also important.

Physical Limnology in Lake Banyoles / Xavier Casamitjana, Jordi Colomer, Elena Roget, Teresa Serra



En: Limnetica. vol. 25, núm. 1-2 (2006) , p. 181-188

The main physical long-scale processes occurring in Lake Banyoles are reviewed as a tribute to Prof. Margalef. These processes include the water fluxes below the surface of the lake, the behavior of the sediment in suspension in the basins, the heat fluxes at the surface and at the bottom layers, the internal seiching, the formation of a baroclinic current due to differences in cooling between the two lobes, the mixing dynamics, the meromictic behavior of some of the basins and the formation and dynamics of hydrothermal plumes.

Fish ecology in Lake Banyoles (NE Spain): a tribute to Ramon Margalef / Ramon Moreno i Amich, Quim Pou i Rovira, Anna Vila i Gispert, [et al.]



En: Limnetica. vol. 25, núm. 1-2 (2006) , p. 321-334

Lake Banyoles is the second largest lake in the Iberian Peninsula and due to this relative uniqueness, its peculiar geological origin, and its considerable age attracted the early attention of the late Professor Ramon Margalef. One of the first papers by Margalef was on the biota of Lake Banyoles and two of the first four Ph.D. theses that he supervised were about the limnology of this lake. Unfortunately, the uniqueness of this lake also implied that it was the first place of introduction into the Iberian Peninsula of several exotic fish species, early in the XXth Century and nowadays the lake fish assemblage is dominated by invasive species, and some native ones have been extirpated. Although the limnological studies in Lake Banyoles were pioneering within the Iberian Peninsula, studies on fish ecology of the lake did not start until 1989. Thereafter, four Ph.D. theses have been completed on different aspects of the fish assemblages of Lake Banyoles. The aim of this paper is to provide a short overview of this research, largely brought about by the considerable limnological information previously available for this lake, thanks to the insightful, pioneering work of Professor Margalef.

Benthos of Spanish lakes and reservoirs / Narcís Prat i Fornells, Montserrat Real i Ortí, Maria Rieradevall i Sant
Prat i Fornells, Narcís


En: Limnetica. vol. 8 (1992) , p. 221-229

A summary of the results from the study of benthos of lakes and reservoirs in Spain is provided, with a list of the species found to date. Spanish natural lakes are smaller than European lakes; the largest is Lake Sanabria, of glacial origin, which is 3 Km long and half a kilorneter wide. Many are very small and situated in the mountains; more than 200 hundred have been recorded in Spain, but only in Lake Sanabria and Lake Banyoles have the benthos been studied. Lake Sanabria is a cold oligotrophic, monomictic lake with oxygen always present in the deepest zones. Its fauna is similar to that of other central European lakes, with Mici.opsectra c.orztractu (a chironomid) as the dominan1 species. Lake Banyoles is a karstic, monomictic and multibasin lake; despite the low primary productivity, due to the abundante of sulphate in the water, the allochthonous inflow of organic matter and the inflow of water from bottom springs, the profunda1 environinent is very stressing for benthic fauna. Very low oxygen concentrations and high sulphide content in the water and sediments dueto meromixis mean that only the larva of the dipteran Chaohoi.lcs flai7icans was present in one of the 5 basins of the lake. In other basins, when oxygen is available (no meromixis), the fauna is similar to that of tlie inineralized lakes of the Aegean region and some lakes in central Italia. On the other hand, preliminary data from the Pyrenean lakes and from Sierra Nevada ponds reveal no differences with northern cold lakes. Tlie largest lakes in Spain are the reservoirs. There are nearly 1000 and data are available on 100 of them, including the kargest. In addition to oxygen and sulphide content in the bottom waters, water level fluctuation and high sedimentation rates are disturbance factors that prevented the organization of the community. Allochthonous inputs of organic matter are also an important factor both in the reservoirs and also in the small, oligotrophic lakes like Banyoles and Sanabria. As a result the meiofaunal loop is very important in many of the Spanish water bodies . For this reason the natural lakes and reservoirs of Spain are dominated by Oligochaeta, small crustaceans and the microcarnivore chironomids (such as Procladi~ls, Cladopelma and Mi(,rnc.hil-onnmus) that feed on these meoifaunal elements. The phytophagous chironomids, like Chironomus, are only abundan1 in the shallow areas of mesotrophic and eutrophic reservoirs. This situation makes it difficult to apply the typological system of SAETHER which predicts with some confidence only the benthic communities of Spanish natural lakes above 1500 m in the Pyrenees or the ponds above 2000 m in Sierra Nevada mountains. Higher temperatures (which originate a longer stratification period), the presence of sulphate in the waters of the eastern part of Spain and high inputs of sediments and allochthonous organic matter seem to be the factors that originated the differences between the benthic profunda1 faunas of Spanish lakes and reservoirs and those of the temperate lakes of north and central Europe.

Bryozoans of Banyoles lake / Maria Rieradevall i Sant, Josep M. Busquets
Rieradevall i Sant, Maria


En: Limnetica. vol. 6 (1990) , p. 137-146

Data for bryozoan species from Banyoles lake (NE Spain) are presented. Three species have been recorded: Fredericella sultana, Lophopus crystallinus and Plurnatella repens, the first two for the first time in the Iberian peninsula. An examination of the F. sultana colony and the statoblast observations of L. crystallinus and P. repens with the scanning electron rnicroswpe made possible the identification. Details of the floatoblast structure are given.

First record of the asp Leuciscus aspius introduced into the Iberian Peninsula / Roberto Merciai, David Almeida Real, Enric Aparicio, [et al.]



En: Limnetica. vol. 37, núm. 2 (2018) , p. 341-344

The asp Leuciscus aspius (L.), a large piscivorous cyprinid fish, is reported for the first time in the Iberian Peninsula. Five individuals were captured in July 2017 and many other were observed in the Darnius-Boadella Reservoir (Muga river basin, NE Spain). Our observations suggest that the asp has established in the reservoir, representing a potential threat to the native species of the Muga River. As it has been the case with several other alien fish species, the asp is likely to be illegally spread to other Iberian river basins if current management measures do not change.