Applied Ecophysiology: An Integrative Form to Know How Culture Environment Modulates the Performance of Aquatic Species from an Energetic Point of View - Aquaculture and the Environment: A Shared Destiny - page 178

the addition or removal of ammonia. Glutamate cycle ( GC ) is represented by a circle
attached to KC. The amino group can be transferred to glutamine, which is less toxic than
NH 4 , so is involved in nitrogen excretion through the gills. The amino group can also be
coupled to a carbohydrate to the formation of glucosamine for chitin formation.
Therefore, growth and immunity of juveniles of L. vannamei are linked to domestication
and protein metabolism.
The hematopoietic tissue and hemocytes are represented in the model under a deep
interaction with the GD and the nervous system, since nutritional status and some
hormones affect the rate of proliferation of hemocytes and thus the state of the immune
response, because in the hemocytes are synthesized many of the immune effectors. On the
other hand, the concentration of hemocytes in the epidermis during some stages of moult
may be related to the release of glycogen for the synthesis of chitin, which is consistent
with the ability of hemocytes to synthesize glycogen and store huge amounts
(proportionately greater than content in the digestive gland). Also, the high amount of
amino acids within the hemocytes could point to a possible release into the hemolymph
associated with osmotic regulation and/ or energy demand Claybrook, (1983). Since the
metabolic functions of hemocytes have not been demonstrated, in the model are marked
with a dashed arrow.
4.3 Effect of temperature on energy losses during southern king crab larval
development
Temperature is one of the most important environmental factors affecting every aspect of an
organism's physiology, from the basic structures of the macromolecules that are responsible
for catalysis and information processing to the rates at which chemical reactions occur
Hochachka & Somero, (2002). Thus, energy acquisition, losses, allocation to maintenance
and growth in any organism is affected by temperature. In heterotrophic organisms, the
ingested food provides the energy input which is balanced with the main sources of energy
losses i.e. bio deposition or faeces rejection, metabolism quantifiable by the oxygen
consumption rate, and in less extent nitrogen excretion. The reminder energy is canalized to
growth and/or reproduction. In a lecithotrophic (i.e. food independent) condition, the
principal energy losses are related to respiration and nitrogen excretion.
The lithodids, commonly known as king crabs or stone crabs, inhabits high latitude cold
waters of both hemispheres. Several species of king crabs represent valuable fisheries but
commercial exploitation and environmental factors has dramatically declined the
landings. In the southernmost part of South America (Chile and Argentina) Lithodes
santolla (Molina), the southern king crab, is commercially exploited and severe fishing
restrictions are necessary to protect the populations. Both circumstances increased the
interest and expectative about the development of cultivation technologies for the
southern king crab.
In order to establish larval rearing conditions, ecophysiological studies on L. santolla larvae
have been carried out to define culture temperature based in the energy losses.
Early life-history stages tolerate low temperatures and their larval development is fully
independent of food (lecithotrophic) Anger et al., (2004); Calcagno et al., (2004); Kattner et
al., (2003); Lovrich et al., (2003); Thatje et al., (2003).