Llanos in the Rio Apure basin, state of Apure, Venezuela
80th place in Biotope Aquarium Design Contest 2017
Italy. Daniele Maxia
Volume: 180 L
Dimensions: The Tank is self-built and it measures 80x60x45cm (at water surface level)
List of fishes: Mikrogeophagus ramirezi (Myers e Harry 1948) male (longfin) female and some fry (about two months old). Physa marmorata (Guilding, 1828).
List of plants: Echinodorus bolivianus angustifolius, Echinodorus tenellus, Eichhornia azurea (floating and submersed form), Eichhornia diversifolia, Eleocharis sp., Eleocharis xingu, Heteranthera zosterifolia, Ludwigia inclinata.
Description of decorations: The bottom consists of a layer of peat covered with abundant amber quartz sand, currently partially naturally covered with organic material. Hard-scape consists of two pieces of woods (for aquarium use).
Description of equipment: Lighting: one 150w CFL lamp 6400K (14000 lumens) with reflector (aircooled reflector Spudnik 150, 97% reflection). Photoperiod is 12 hours (set for comfort 8:00-20:00) Filtration: external self-built 3-stage filter: mechanical coarse, fine mechanical, mechanical ultrafine (anti-sediments cartridge) with delivery pump 1000 L/ h (Aquabee up1000). Aspiration and discharge occurs through transparent (unmovable) pipes passing through the bottom of the tank. Heating: external in-line heat exchanger (Hydor ETH 200) set at 27 °C. CO 2 supply system: cylinder system with external in-line diffuser (JBL ProFlora Direct).
Water parameters: transparent water obtained by adding to RO water buffers, salts and low concentrated fertilizers. Temperature: 26.9 ° C, pH 6.6, KH 3, GH 4, CO 2 25-30mg /L, Fe 0.05ppm, NH 3 0ppm, NO 3 10ppm, NO2 0ppm, PO4 0.25ppm (Analysis made with JBL TestLab).
- Description of the area surrounding the biotope: The Apure River is located in western Venezuela and is a major whitewater tributary of the Orinoco River with a lenght of 820 km. The Apure basin includes a small part of the Colombian territory at the headwaters of the Sarare River and its tributary Oirá. The headwaters of the Apure River are in the Andes. Most of the Apure River watershed is located in a vast alluvial plain called the Llanos, which represents a highly productive ecosystem cover for the vast savanna vegetation. Upon reaching the plains, the speed of the Apure waters decreases and slows down its course. The Llanos are a large extension of Venezuela’s lands, from the western Apure to the eastern Monagas. The population density in the Llanos is relatively low and the area is essentially rural. Overall, human influence is not extensive in the basin and the relationship between the river and its floodplain are principally natural. This large zone is seasonally inundated, permitting an extensive interaction between the Apure River and its floodplain.The interaction between the river water and the floodplain play a key role in the Apure River mainstream ecology. The climate in the Llanos is that of a tropical savanna, and it is constituted by a wet and a dry season. The rainy season starts in May and last until November, whereas the dry season extends from approximately November to April. The months with maximum precipitations are June, July and August. During the high water stage, the river inundates its floodplain that remains inundated until November. During the decreasing branch, low water stage and a part of the rising stage, the Apure River remains within its banks, without any contact with the floodplain. The hydrological cycle in the Apure River is accompanied by major changes in the dissolved element concentrations.The temporal variability of these variables is controlled by the changes in the flow values, suggesting that a strong diluition effect is produced during the wet season.Description of the underwater landscape of the biotope: The soil of these flooding areas often consist of silica sands covered with organic matter and broad vegetation. Water is clear, because these areas are mostly flooded by rainwater. Ram’s habitat is quite variable, due to its extension. Rams are normally found in deep water not more than 60cm, normally about 30cm, in areas with no shade. The habitat has free swimming areas and fully covered areas of vegetation that shield from the stream and provide shelter. During the rainy season, Rams move to flooded areas to reproduce. In this natural habitat they spend their time feeding on the organisms found in organic sediments and showing their territoriality by contracting the fins and expelling other Rams or other fish from their territory.
Description of the parameters of the habitat:
Water parameters (in wet-dry season) are: Temperature (ore 12:00) 29.2-27.8°C, pH 6.98(min. 6.41) -7.55, Conducibility 118-115 µS∙cm a 20°C, KH ≤1, GH ≤1, TSS (residuo fisso) 260-305 mg/L, DOC (dissolved organic carbon) 5.10-2.57 mg/L, O2 133-209 mg/L, CO2 20-30 mg/L, HCO3 – 53-65 mg/L, Si5-4.4 mg/L, Na+ 2.9-4.3 mg/L, K+ 2.8-1.8 mg/L, Ca2+ 14.5-16.9 mg/L, Mg 2+ 2.9-3.4 mg/L, Fe 0.15-0.03 mg/L, NH3 0.05-0.3 mg/L.
List of fishes: The Rio Apure has about 400 different fish species. Among the fish present are: Hemigrammus rhodostomus, Carnegiella marthae, Hyphessobrycon cf. axelrodi, Moenkhausia collettii, Pristella maxillaris, Anostomus anostomus, Poecilia reticulata, Apistogramma macmasteri, Aequidens diadema, Mesonauta insignis, Satanoperca daemon, Cichla orinocensis, Pygocentrus cariba, Potamotrygon orbignyi, Leporinus fasciatus, Corydoras aeneus, C. habrosus, Otocinclus affinis, Farlowella vittata, Glyptoperichthys gibbiceps, Hypostomus plecostomus, Panaque nigrolineatus.
List of plants: Plants biodiversity reach 200 species, and we can find: Cabomba furcata, C. aquatica, Echinodorus tenellus, E. bolivianus, Eichhornia azurea, E. crassipes, E. diversifolia, Eleocharis sp. Eriocaulon cinereum, E. sp., Heteranthera limosa, H. reniformis, Hygrophila guianensis, Lemna sp., Limnobium laevigatum, Ludwigia helmintorrhiza, L. inclinata, L. inclianta var. verticillata, L. sedoides, Najas indica, Nymphaea rudgeana, Pistia stratioites, Phyllanthus sp., Rotala mexicana, Sagittaria guyanensis, Syngonanthus sp., Utricularia sp.
Threats to the ecology: N/A.
Sources of information:
- Mora A, Baquero JC, Alfonso JA, Pisapia D, Balza L. 2010. The Apure River: geochemistry of majorand selected trace elements in an Orinoco River tributary coming from the Andes, Venezuela. DOI: 10.1002/hyp.7801
- Lasso CA, Mojica JI, Usma JS, Maldonado OJS, DoNascimiento C, Taphorn DC, Provenzano F, Lasso-Alcalá OM, Galvis G, LVásquez L, Lugo M, Machado-Allison A, Royero R, Suárez C,Ortega-Lara A.Peces de la cuenca del río Orinoco. Parte I: lista de especies y distribución por subcuencas Revista: Biota Colombiana 2004 5 (2)
- Rial B., Anabel Diversity, bioforms and abundance of aquatic plants in a wetland of the Orinoco floodplains, Venezuela Biota Colombiana, vol. 15, núm. 1, enero-junio, 2014, pp. 1-9 Instituto de Investigación de Recursos Biológicos "Alexander von Humboldt" Bogotá, Colombia
- Lasso, C. A., J. S. Usma, F. Trujillo, A. Rial (Editores). 2010. Biodiversidad de la cuenca del Orinoco:bases cientificas para la identificacion de areas prioritarias para la conservacion y uso sostenible de la biodiversidad. Instituto de Investigacion de Recursos Biologicos Alexander von Humboldt, WWF Colombia, Fundacion Omacha, Fundacion La Salle e Instituto de Estudios de la Orinoquia (Universidad Nacional de Colombia). Bogota, D. C., Colombia. 609 pp.
- Mora, Abrahan & Laraque, A & Moreira-Turcq, Patricia & Alfonso, Juan. (2014). Temporal variation and fluxes of dissolved and particulate organic carbon in the Apure, Caura and Orinoco rivers,Venezuela. Journal of South American Earth Sciences. 54. . 10.1016/j.jsames.2014.04.010.
- Rial, Anabel. (2007). Flora y vegetación acuática de los Llanos de Venezuela con especial énfasis en el humedal de los llanos de Apure.. 99- 106.
- Kasselmann C. Aquarium Plants. 2003. ISBN: 1575240912