Growth and proteolytic
activity of Octopus vulgaris paralarvae with different food rations
during first feeding, using Artemia nauplii and compound diets
R.
Villanueva, N. Koueta, J. Riba, E. Boucaud-Camou-2002
Aquaculture, 205(3-4): 269-286
Abstract:
Experiments were conducted to investigate growth and
proteolytic activity of the common octopus Octopus vulgaris, reared
with different diets and ration levels during first feeding. Four ration
levels were tested, 0.2, 2, 4 and 10 Artemia nauplii ml-1
day-1 and co-feeding techniques were tested using 10 Artemia
nauplii ml-1 day-1 plus three different compound
millicapsules. Total proteolytic activity, trypsin and chymotrypsin levels
were recorded from eggs, hatchlings and during the first month of paralarval
rearing. Five days after hatching, paralarval weight and proteolytic
activity was dependent on food ration. The low-food treatment did not lead
to an increase in hatchling weight, in contrast with the positive increase
of the other treatments. After 20 days, best survival was observed in
treatments fed 2 and 4 nauplii ml-1 day-1. High
nauplii rations of 10 nauplii ml-1 day-1 plus
millicapsule diet treatments produced higher growth and higher proteolytic,
trypsin and chymotrypsin levels, but poor survival. Total proteolytic
activity was correlated with paralarval weight, whereas trypsin and
chymotrypsin were maintained at hatchling levels only for the high food and
co-feeding treatments, and decreased in the others. The trypsin activity in
the high-food treatment showed a sharp increase after 15 days and 880 µg of
the mean dry weight (2.5 times hatchling weight). Millicapsules were
ingested by the paralarvae after 5 days but did not lead to a significant
increase in weight. Enriched Artemia nauplii seem to be useful only
as an initial diet until a doubling in hatchling weight is achieved. This
period can extend from 11 to 14 days at 20 °C, after which a larger prey
and/or suitable microdiet is required.
(Centro
Mediterráneo de Investigaciones Marinas y Ambientales, CSIC, Instituto de
Ciencias del Mar, Passeig Maritim 37-49, E-08003 Barcelona, Spain, Tel.:
+34-932216416; fax: +34-932217340, e-mail: roger@icm.csic.es)