Marisia - Maros Megyei Múzeum Évkönyve 32/1. (2012)
Zoology
Gabriela GRIGORAS, Marcela ROSCA shown that these plant species are able, within certain limits, to adapt to color light spectrum (chromatic adaptation) due to their assimilatory pigmentation (Kasselmann, 2003) and this process can take several weeks. However, the observations regarding the plants growing rate, leaves integrity, pigmentation system development (e.g. enhancement of brown and red coloring agents carotenoids) was made in order to assess the effect of light quantity and quality, daily and seasonally photoperiod on plants physiology. But many other factors (that partially will be discussed below) act on the plants photosynthesis, that’s why this assumption may raise controversy and it was not treated exclusively. A poor light leads to the deficient plants growing, increased internodes length or leaves decomposition. Carbon dioxide content, alkalinity, water hardiness. The carbon represents a vital element for the nutrition of higher plants. The aquatic plants allow their carbon requirements from the different inorganic carbon compounds in water (CO, - carbon dioxide, H,CO, - carbonic acid, HCO 3 - hydrogen carbonate, C032 - carbonation, Са(НСО^)2 - calcium hydrogen carbonate). Carbon dioxide which transforms to carbonic acid by combining with water constitutes one of the most essential nutrients for the plants photosynthesis and this is extracted from the water through the plants assimilation process. As soon as the carbon dioxide in the water has been exhausted, the plants will behave very differently. Whereas in some species growth will cease, other aquatic plants are able to also assimilate and utilize the hydrogen carbonate ions (biogenic decalcification) and this is the case of aquatic tropical plants species that populate natural habitats with calcium — rich water and an alkaline pH value. We have in view some future studies for ‘building’ of these kind of phytocoenosis in order to obtain a good enrichment environment for ex-situ conservation of Scardinius racovitzai, a critically endangered fish from Petea thermal ecosystem. The plants origin used during the present experiments live in weak acid, calcium and salt deficient water which contains an enough supply of free carbon dioxide and carbonic acid. Most of them have an extreme dependency on this gas and they are not or are only to a limited degree, able to extract hydrogen carbonate from the water. For their photosynthesis efficiency, an enough supply of carbon dioxide, above all, is essential in the aquarium because the CO, content. A small installation (with CO, reusable cylinder, solenoid valve, counter bubble, water/ gas reactor, pH controller) allows an additional and optimum C02 supply and maintains the pH value between 6.3-6.55. For the plants growing in aquariums, not only the relationship between pH value and carbon dioxide content is important but also the connection between carbonate hardness (also referred to as alkalinity or acid-binding capability) and carbon dioxide. The higher carbonate hardness the more carbon dioxide is required to maintain de the calcium hydrogen carbonate in soluble form, in other words to prevent the precipitation of lime. That’s way we use a RO filtration apparatus in order to remove the mostly high carbonate hardness from tap water. Aquarium water with a low KH has decreased pH stability. Our target is to have a basic water source with a KH between 3—5°G and we obtain good results in plants and fish welfare. 122
