De grootste kennisbank van het HBO

Inspiratie op jouw vakgebied

Vrij toegankelijk

Terug naar zoekresultatenDeel deze publicatie

Indicatoren voor groeilimitatie bij buitenkweek van microalgen

Rechten: Alle rechten voorbehouden

Indicatoren voor groeilimitatie bij buitenkweek van microalgen

Rechten: Alle rechten voorbehouden

Samenvatting

The research described in this report was conducted for IMARES Yerseke in context of the European project REPROSEED. REPROSEED stands for: Research to improve PROduction of SEED which aims on the promotion and improvement of the production of shellfish seed in hatcheries and nurseries. The project consists of several parts, one of them is the production of algae for the nursery phase, this research is related to that part. The study was conducted in the period from February till May 2012.

To optimize the cultivation of algae, one is looking for indicators which show whether the limiting factor for the growth of algae cultures is either light or nutrient deficiency. A potential indicator is the absorption ratio of pigment measured at wavelengths of 480- and 665 nm. This shows the ratio between carotenoids and Chlorofyl-a (Riegman & Rowe, 1994). The researchers Riegman & Rowe (1994) considered a ratio of 1 as an extreme limitation by light and a ratio of 2 as an extreme for nutrient limitation. The research presented is done because the previously mentioned relation between the limitation and ratio is never tested in an experimental design, but is derived from monitoring the Wadden Sea. It is unknown whether the indicator can be used for intensive algae cultivation.

In addition, measurements were performed using PAM (Pulse Amplitude Modulation). With PAM the Fv/Fm and Fm values can be measured. These values indicate how efficient the photosynthetic system works under the present light and nutrient conditions and are expected indicators for light and nutrient limitation
To show the causal link between these indicators and nutrient- and light limitation, algae are grown in so-called raceway systems. In different experiments nutrient and light limitation is applied to the cultures, in which the rate of algal growth (Skeletonema costatum) in control cultures is used as an indicator for the presence of a limitation.
The experiments show that the applied limitations, which are clearly reflected in the growth, show no changes of the absorption ratio compared to the control cultures. Only one experiment shows a difference in absorption ratio compared to the control in the last two days of the experiment. However at this stage the cultures of Skeletonema costatum were collapsing and almost vanished. If the absorption ratio would be applied in practice, it is important that the ratio shows a limitation of light or nutrients throughout the exponential growth phase, so that the management of the cultures can be adjusted in time. If the ratio shows only changes which indicate limitation of light or nutrients when the cultures are collapsing and thus in the crash phase condition of the cultures, changes in the culture systems will be too late. Collapsed cultures cannot be restarted. If the absorption ratio shows no clear limitation during the exponential phase, then it cannot be used as an indicator for light- and nutrient limitation. This is the case for this study, therefore the absorption ratio is unsuitable as an indicator for limitation
The Fv/Fm ratio during the experiments did not diverge from the control cultures and did not indicate limiting conditions despite the obvious ruling limiting conditions. This makes the Fv/Fm ratio for similar setups unsuitable as an indicator for limitation. In case of light limited conditions the maximum fluorescence (Fm) showed clear differences compared to the control cultures. This was reflected in a lower Fm for the limited cultures, where the available light is absorbed more effective. This Fm can be used to indicate poor light conditions, but is unsuitable as an indicator of nutrient limitation.

Toon meer
OrganisatieHZ University of Applied Sciences
OpleidingWatermanagement/ Aquatische Ecotechnologie
InstituutDelta Academy
PartnersIMARES, Yerseke
Gepubliceerd in
Datum2012-06-26
TypeBachelorscriptie
TaalEngels

Op de HBO Kennisbank vind je publicaties van 25 hogescholen

De grootste kennisbank van het HBO

Inspiratie op jouw vakgebied

Vrij toegankelijk