Dimensions 150 × 60 × 60 cm

Title Banks of the creek "El espinillo" in the dry season. Magdalena Buenos Aires. Argentina.

Volume 540L

Background The baclground of the aquarium has a black vinyl

Lighting The aquarium lighting is based on 3 led 6000k reflectors.

Filtration The aquarium is equipped with 2 Atman 3338 canister filters, with biological and mechanical material.

Plants Ceratophyllum demersum, Ranunculus apiifolius, Schoenoplectus californicus.

Animals The fish species that inhabit this aquarium were collected directly from the water system; These species are: Astyanax stenohalinus (30), Australoheros facetus (3), Bryconamericus iheringii (1), Corydoras paleatus (8), Gymnogeophagus meridionalis (2), Pimelodella laticeps (2).

Materials All the elements used in this aquarium, such as the substrate, wood, plant detritus, stones, rocks, empty shells of snails and bivalves and plants, were collected from the aquatic system and arranged to imitate the chosen biotope and also be able to maintain and learn more about it through a wild aquarium at home.

Additional Information The creek "El Espinillo" is a tributary of the Río de la Plata, it is tlocated in the Magdalena district, province of Buenos Aires, in Argentina.The location coordinates of the stream are 35°08'08.7"S, 57°42'35.2"W.It is approximately 30 kilometers long with an average depth of 60 or 70 cm approximately in its deepest part in the dry season. It flows into the Río de la Plata. It is of slow course and the clarity of the water varies according to the zones and the amount of water that it drags. During periods of heavy rain, it can reach heights in the depth meter, causing it to overflow and flood the surrounding fields. It has a scarcely sloping channel, the substrate is characterized by the predominance of silty-clayey sediments, with abundant organic detritus, dug in Cenozoic sedimentary deposits of scarce current. The edges are determined by slight ravines.

In general it is fed by rains fallen in the vicinity and by springs, contributing also the contribution of groundwater in some areas of the basin. The Espinillo creek has the peculiarity that in its middle section develops the "Cañada de Arregui", a group of poor drainage areas, interconnected by more depressed areas of permanent and temporary regime. In its middle sector, it forms a flat depression, permanently flooded of scarce depth, the lagoon of Arregui.

Its waters are slightly alkaline in natural form, with 8pH and a hardness of water of 8 ° dh. due largely to the calcareous substrate (Tosca). The hardness of the water is high and also the conductivity, which can fluctuate depending on the land it crosses, by contributions of the groundwater that in some cases can be strongly mineralized, by the existence of exposed coastal strips, after the descent of the old "Querandinense Sea", which have a large percentage of shell in its composition, or because of the influence of pollution by intensive livestock in the area.
The temperature of the water in the dry season in the middle of March gave a value of 22ºC. The values ​​of No2 resulted in 0 mg / L and the No3 values ​​with an approximate value of 12.5 mg / L. (These values ​​were surveyed with tests for aquariums).

The contribution of plant detritus from the creek "El Espinillo" generally comes from the grasslands and bushes that surround it during its course. However, the scarce slope causes the stagnation of the water in the dry season and increase in transparency, which favors the development of numerous submerged and floating plants in the backwater area.

At the edge of the creek there are reedbeds of Schoenoplectus californicus, associated with other marsh plants such as Typha dominguensis and Solanum malacoxylum.
Among the submerged or floating plants we can find Ceratophyllum demersum, Myriophyllum elatinoides, Potamogeton striatus, Potamogeton sp., Chara sp., Lemnaceas, Ludwigia peploides, Hydrocotyle ranunculuides and Ranunculus apiifolius.
Associated with the vegetation can be found bivalves like Gundlachia concéntrica and ampullar as Pomacea canaliculata; It is common to find on the substrate a good amount of empty shells of the latter mentioned because they are the food of several species of birds that live in the vicinity of the creek. There are also abundant cladocerans and copepods, as well as dipterous larvae.

The waters of this creek have good aquatic diversity, abundant in the dry season. Can be found some families of fish included Characidae such as Astyanax stenohalinus (Messner, 1962), Bryconamericus iheringii (Boulenger, 1887) and Oligosarcus oligolepis (Steindachner, 1867); Crenuchidae as Characidium rachovii (Regan, 1913); Cichlidae such as Australoheros facetus (Jenyns, 1842), Crenicichla scottii (Eigenmann, 1907) and Gymnogeophagus meridionalis (Reis and Malabarba, 1988); Erythrinidae as Hoplias malabaricus (Bloch, 1794); Callichthyidae as Corydoras paleatus (Jenyns, 1842) and also species of the family Heptapteridae as Pimelodella laticeps (Eigenmann, 1917).
Also found in large quantities, crustaceans such as Palaemonetes argentinus (Nobili, 1901).

In its surroundings you can also find a diverse terrestrial fauna.
Many species of birds inhabit the place, such as Ciconia maguari, Cisne coscoroba, Pseudoleistes virescens and Sturnella superciliaris.
The area is also inhabited by populations of Myocastor coypus, which make their caves and nests along the banks of the creek and the reed beds.

All the information gathered in this work comes from the personal on-site survey of this water system, which was turned into a web page and a Facebook fan page.

In them you will find photographs and videos of the area made by me and my partner in the project.

https://www.facebook.com/proyectoarroyoespinillo/

https://proyectoespinillo.wixsite.com/proyectoespinillo

https://youtu.be/uyjRLrXabC8

The specific information on the Limnological characteristics was consulted in the following links and articles.

http://www.alestuariodelplata.com.ar/atalaya.html
http://petmagdalena.blogspot.com/2012/10/caracterizacion-ambiental-del-medio.html?m=1

A benthic view of streams and Pampean Rivers - A. Rodrigues Chapter, C. S. Ocon and M. Tangorra (Institute of Limnology "Dr. Raúl A. Ringuelet")