Stagionalità dell'Artemia nei piccoli laghi ipersalini (il modello Aphemo)
Author(s)
Eusepi, Emanuele
Date Issued
June 10, 2014
Type
Doctoral Thesis
Abstract
Given the importance, from a scientific point of view that economic, individuals of the
genus Artemia in aquaculture, in the context of this thesis it was decided to analyze the ecology and
seasonality of an anphigonic population of Artemia in a hypersaline lake. For this objective was
developed a mathematical model (APHEMO, Artemia salina Phenological MOdel) capable of
simulating the seasonality of Artemia, more annual cycles seamless, in a crystallization pond of the
Natural Reserve of Saltwork of Tarquinia, and in semi-natural environment confined and controlled
(experimental mesocosm).
The crystallization pond of Tarquinia, is a system characterized by high salinity values
(between 100 and 350 g/l) and in which changes in the water level depend only on precipitation and
evaporation. In this site were carried out for three years, weekly sampling for the estimation of the
parameters of the model and its validation.
The experimental mesocosm instead is an artificial system made in a tank outside of the
center ichthyogenic experimental marine of Tarquinia Saltwork (CISMAR) size of 25 m3, in which
they were reared individuals of Artemia, taken from the tank crystallization, in successive
generations in a controlled salinity (values below 170 g/l) for a further validation of the model; also
in the experimental mesocosm were taken weekly samples for a period of two years, the same way
as those carried out in the crystallization pond.
The APHEMO model is based on the theory of the sum of the rates, and simulates the
duration of seasonal cycles (presence of live Artemia) in hypersaline environment, the number of
generations and their time interval for each cycle, and period's duration of diapause (presence of
dormant cysts) in function of the water temperature and salinity (forcing variables of the model), on
more annual cycles (3 years of data). The model is characterized by a rate function in two variables
(water temperature and salinity), characterized by a polynomial of the third degree whose
parameters were obtained from literature data, and the parameter threshold salinity expressed with
the Heaviside function. The state variable of the model is the development index, whose values
depend on the time, and returns the daily degree of advancement of Artemia population in
successive generations.
After a first sensitivity analysis, the model was validated by comparing the observed (pond
crystallization and experimental mesocosm) and simulated ones obtained with APHEMO. In this
research, it has been proposed a model, validated on two different situations at the same time, with
positive results in both cases. The results obtained showed that the model is able to reproduce with a
low margin of error seasonality of Artemia (in hypersaline environment, natural and semi-natural)
simulating both the duration of the periods of diapause that seasonal cycles seamless continuity
over a period of 3 years. For the seasonal cycles, it is possible to simulate with APHEMO the
number of generations, but this data cannot be validated because the generations tend to overlap in
nature.
Considering the almost total absence of Artemia models in literature, as found by the
literature research carried out as part of this thesis, APHEMO can be seen as a first model of
anphigonic Artemia population, with its limits and it can certainly be improved and implemented
for the sustainable management of the resource Artemia, both in nature and in aquaculture,
increasing its potential.
Additional information
Dottorato di ricerca in Ecologia e gestione delle risorse biologiche
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