| Abstract |
The present study aimed to determine the biological requirements of the triton
Charonia seguenzae (Aradas & Benoit, 1870) in order to maintain adult individuals
under welfare conditions and reproduce. The scientific objectives were grouped into
four modules that cover a wide range of the life cycle of the triton providing
information about its biology and ecology.
The first module concerned the nutritional requirements (quantitative and
qualitative), feeding preference and feeding behavior of the tritons under three
different temperatures (17, 20, 23°C). The results showed that the tritons consumed
all the foods that were provided (natural preys and alternative foods) displaying high
levels of feeding adaptation and "flexibility". Although tritons preferred consuming
sea cucumbers, in the majority of the trials they preferred to feed on a variety of
species. Regarding quantitative nutritional requirements of the tritons, the daily food
consumption of tritons, Charonia seguenzae, ranged from 0.32 to 3.67% of their
weight, and depended on the type of food and the temperature. Sea cucumbers were
the food with the best nutritional indexes and 23oC the optimal temperature.
In the second module, the predation behavior of tritons and day and night
activity were studied. The knowledge of the predation pattern and its interaction with
the day and night activity of C. seguenzae will contribute to the design of monitoring
strategies and census techniques. The tritons follow the patern of active predation.
During predation, tritons increase their moving speed, which is more than twice the
speed of the prey (sea cucumber). The day and night activity of the tritons was
affected by the stomach repletion with the fasted individuals being more active than
the saturated ones. Another factor that affected day-night activity was light with the
tritons being more active during the day.
The third module concerned the reproduction of tritons and provided
important information on their biology, behavior and ecology, such as the temperature
range in which reproduced (20 to 23°C) and the demonstration of parental care. Two
aspects of their biology were of particular interest, polyandry demonstrated by the
females, and collaborative care of embryonic sacks posed new questions both in
ecological and evolutionary level. The fourth module concerned the effect of temperature and maternal size on
fertility levels and embryonic development. Although the maternal size affected the
egg-capsules dimensions with the larger individuals laying larger capsules, fertility
levels were not affected the same way. The temperature did not affect fertility, but
had a crucial role in embryonic development, affecting developmental time,
embryonic size and deformities. The combined results of the two previous modules
showed that the tritons invest in producing many offsprings, offering them protection
by placing the embryos in protective capsules which they continue to protect and
nourish. At the same time, they ensure a wide dispersal of their offsprings through the
existence of a long pelagic larval stage.
Temperature affected all the studied life stages of the tritons. The optimal
temperature, in terms of nutrition, reproduction and embryonic development, ranged
from 20 to 23°C. On the other hand, maintenance at 17°C proved problematic
concerning tritons’ nutrition, was out of the temperature range in which the tritons
reproduce and led to the emergence of a large deformation rate during embryonic
development (when applied at an early stage of ontogenesis).
|
Προσδιορισμός των βιολογικών απαιτήσεων του τρίτωνα Charonia seguenzae (Aradas & Benoit, 1870) προκειμένου να επιτευχθεί η συντήρηση υπό συνθήκες «ευζωίας» ενηλίκων ατόμων και η αναπαραγωγή
