AQUACULTURE EUROPE 2005 CONFERENCE TO ADDRESS AQUACULTURE SUSTAINABILITY
– “LESSONS FROM THE PAST TO OPTIMISE THE FUTURE”
The events organised at the occasion of Aquaculture Europe
2005 in Trondheim this summer promise to create an all round and very lively
meeting place. As of today interest has been expressed in attending from 40
countries worldwide and interest inquiries keep arriving.
These events are linked to the further development of SUSTAINABLE
AQUACULTURE and are taking place in Trondheim, Norway from August 5-12:
ABUNDANCE AND GROWTH RESPONSE OF MICROALGAE AT MEGALON EMBOLON SOLAR SALTWORKS
IN NORTHERN GREECE: AN AQUACULTURE PROSPECT
Nicolas P. Dolapsakis, Triantafyllos Tafas, Theodore J. Abatzopoulos, Stephanie
Ziller, Athena Economou-Amilli-2005
Journal of Applied Phycology 17: 39-49
Abstract:
There is continuous interest in many countries in maintaining and manipulating
the rich ecological value of hypersaline ecosystems for aquaculture. The Megalon
Embolon solar saltworks (northern Greece) were studied in sites of increasing
salinity of 60–144 ppt to evaluate Dunaliella salina abundance and microalgal
composition, in relation to physical and chemical parameters. Cluster and ordination
analyses were performed based on the biotic and abiotic data matrices. Using
fresh aliquots from 60 and 140 ppt salinity waters, phytoplankton performance
was appraised with flask cultures in the laboratory by varying the inorganic
PO4-P concentration at 23 .C and 30 .C. At the saltworks, among the most abundant
microalgae identified were species of the genera Dunaliella, Chlamydomonas,
Amphora, Navicula, and Nitzschia. Dunaliella salina populations were predominant
comprising 5–22% of the total microalgal assemblages during spring, but
only 0.3–1.0% during the summer, when grazing by Artemia parthenogenetica
and Fabrea salina was intense. D. salina cell density in April–July was
in the range of 0.4–12.5 × 106 L-1 with typical densities of 1.5–4.5
× 106 L-1. Overall, microalgal densities were high in salinities of =100
ppt when inorganic-P concentrations were =0.20 mg L-1 within saltworks waters.
Multivariate analysis of species abundance showed that algal growth responses
were primarily related to variation in salinity and inorganic-P concentrations,
but also to NO3-N concentration. In the laboratory, experiments indicated effective
fertilization and denser microalgal growth under high inorganic PO4-P applications
(4.0 and 8.0 mg L-1) at 60 ppt salinity and 23 .C. The lower PO4-P applications
(0.6–2.0 mg L-1) were more effective at 60 ppt salinity and 30 .C. At
140 ppt salinity, microalgal growth response was less obvious at any of the
corresponding phosphorus concentrations or temperatures. In both salinity experiments,
Dunaliella salina bloomed easily andwas predominant among the microalgae. Our
observations indicate that Dunaliella salina populations and the overall rich
microalgal profile of the saltworks, along with their performance in laboratory
mono–and mixed cultures hold promise for mass cultivation within the M.
Embolon saltworks basins.
(Faculty of Biology, Department of Ecology and Systematics, University of Athens,
Panepistimiopolis, Athens, Greece; email of
N.
Dolapsakis: ndol@biol.uoa.gr)
NUTRITIONAL VALUE OF BRINE SHRIMP CYSTS AS A FACTITIOUS FOOD FOR ORIUS LAEVIGATUS
(HETEROPTERA: ANTHOCORIDAE)
Patrick De Clercq, Yves Arijs, Thomas Van Meir, Gilbert Van Stappen, Patrick
Sorgeloos, Koen
Dewettinck, Marjolaine Rey, Simon Grenier, Gerard Febvay-2005
Biocontrol Science and Technology 15(5): 467-479
Abstract:
Decapsulated cysts of the brine shrimp Artemia franciscana were assessed as
a factitious food for rearing the anthocorid predator Orius laevigatus. Developmental
and reproductive traits of O. laevigatus reared for a single generation on A.
franciscana from three geographical locations or on gamma-irradiated eggs of
the Mediterranean flour moth Ephestia kuehniella were compared. There was no
effect of diet on nymphal survival but nymphal period on E. kuehniella eggs
(12.2 days) was 0.7_/1.6 days shorter than on the Artemia diets. The predator
developed 0.5_/1 day faster on cysts from San Francisco Bay (USA) than on cysts
from Great Salt Lake (USA) or Macau (Brazil). Fecundity on brine shrimp cysts
from different locations was similar to that on flour moth eggs (142_/187 eggs/female).
The biochemical composition of decapsulated cysts from San Francisco Bay was
compared with that of E. kuehniella eggs. Depending on the type of analysis,
Artemia cysts contained higher or similar amounts of protein as compared with
E. kuehniella eggs, but amino acid patterns were generally similar. Flour moth
eggs were almost three times richer in fatty acids than brine shrimp cysts,
with some marked differences in fatty acid profiles. Because nutrient imbalances
in a diet may be expressed only after several generations of rearing, the predator
was cultured for three consecutive generations on A. franciscana cysts from
San Francisco Bay. In the third generation on brine shrimp cysts, nymphs took
18% longer to develop, and adults were shorted-lived and about 60% less fecund
than those maintained on E. kuehniella eggs. Brine shrimp cysts may be used
as a supplement in the mass production of O. laevigatus but may not be a suitable
food for long-term culturing of the predator.
(Laboratory of Agrozoology, Department of Crop Protection, Ghent University,
Ghent, Belgium, email of P. De Clercq:
patrick.declercq@UGent.be)
GONAD DEVELOPMENT, GROWTH, SURVIVAL AND QUALITY TRAITS IN TRIPLOIDS OF THE PROTANDROUS
HERMAPHRODYTE GILTHEAD SEABREAM SPARUS AURATA (L.)
Pierrick Haffray, Jean-Sébastien Bruant, Jean-Michel Facqueur, Alexis
Fostier-2005
Aquaculture 247 (1-4): 107-117
Abstract:
The effect of triploidy on the protandrous hermaphrodite gilthead seabream,
Sparus aurata, was evaluated from 2 g to 1347 g (42 months old). No difference
of growth was recorded until 484 g (17 months old), 2n and 3n being all males.
From 20 to 42 months old, the 3n exhibited a lower growth, the difference increasing
to 15.3% at the end of the experiment. At the two reproductive seasons studied,
3n matured as males. The 2n and 3n males had the same weight throughout the
experiment. It is postulated that the 2n's advantage is mainly due to the occurrence
of their feminisation, the 2n females presenting a significant better growth.
Out of the breeding seasons, the 3n presented higher gutted yields (from 0.5%
to 2%) and a lower level of lipid concentration in the muscle (from - 7.5% to
- 17.5%). The fillet of the 2n females is more fatty than the fillets of the
2n and 3n males. This study demonstrated that until the common commercial weight
(480 g), 3n present the same growth as 2n and do not exhibit a difference in
survival, processing yields and quality traits. For bigger sizes, 3n are lower
performers in growth but are leaner and have a better gutted yield. As no spawning
behaviour was observed in this land based farm, these results need to be evaluated
in sea cages in which breeders spend 3–4 months a year in spawning.
(SYSAAF, Station SCRIBE, Campus de Beaulieu, 35042 Rennes, France; email of
P. Haffray:
haffray@beaulieu.rennes.inra.fr)
EXAMINATION OF LARVAL MALFORMATIONS IN AFRICAN CATFISH CLARIAS GARIEPINUS FOLLOWING
FERTILIZATION WITH CRYOPRESERVED SPERM
Edit Miskolczi,, Szilvia Mihálffy, Eszter Patakiné Várkonyi,
Béla Urbányi, Ákos Horváth-2005
Aquaculture 247 (1-4): 119-125
Abstract:
In our earlier experiments on the cryopreservation of African catfish (Clarias
gariepinus) sperm a high number of malformed individuals were found among the
larvae hatched from eggs fertilized with frozenthawed sperm. In our present
study we explored one of the possible reasons of this malformation by examining
the ploidy of the larvae. Sperm was frozen in a 6% fructose extender containing
10% methanol and 10% DMSO as cryoprotectant. Sperm was drawn to straw of different
volumes (0.25, 0.5 and 1.2 ml). Freezing was carried out in liquid nitrogen
vapor. Fifteen grams or thirty grams of eggs were used for fertilization. Chromosome
preparations were made of non-feeding larvae. Fifty to one hundred larvae were
incubated in 0.05% colchicine for 3 h then in a hypotonic 0.075M KCl solution
for 25 min. Larvae were fixed in a 3:1 solution of methanol and acetic acid,
then cell suspensions were made in 50% acetic acid. The suspensions were spread
on slides and stained in 4% Giemsa for 8 min. Chromosome counting and evaluation
was done at 1200× magnification on well spread metaphases. A majority
of the hatched larvae were diploid, with 56 chromosomes. Surprisingly some of
the malformed larvae hatched from eggs fertilized with cryopreserved sperm were
haploids. Haploids occurred only when 0.25 or 0.5 ml straws were used for freezing.
One possible explanation of haploidy is that the genome of the fertilizing spermatozoon
is damaged during the process of freezing thus it can still move and fertilize
the egg but its genome does not take part in the development of the embryo.
This hypothesis is supported by the fact that no haploids were found among the
malformed larvae of the control group which was fertilized with fresh sperm.
(Department of Fish Culture, Szent István University, H-2103 Gödöllo,
Páter K. u. 1., Hungary; email of E. Miskolczi:
miskolczi.edit@mkk.szie.hu)
RELATIONS BETWEEN EGG SIZE, REPRODUCTIVE SUCCESS AND GROWTH PERFORMANCE OF PROGENY
IN ISOGENIC OREOCHROMIS NILOTICUS LINES
Andreas Müller-Belecke-2005
Aquaculture 247 (1-4): 127-134
Abstract:
The present study followed the reproductive performance within four genetic
groups of Oreochromis niloticus females belonging to two homozygous isogenic
lines (C1, C2) developed by induced gynogenesis, a heterozygous isogenic line
(C1 × C2) resulting from crossbreeding C1 and C2, and a heterogenic control
group. Each genetic group consisted of 12 females and observations continued
for 60 days. Digital photographs were taken of the egg batches and hatching
larvae. With the help of image analysing software, the two-dimensional surface
of individual eggs was measured to ascertain egg size. Larval size was also
recorded. To follow their particular growth progresses, isogenic larvae belonging
to C1 and C2 were reared individually from day 6 until day 80 of life under
standardised environmental conditions. Their homozygous isogenic status was
later proven by gene marker studies. In comparison to the heterogenic controls,
the coefficient of variation of egg size was similarly higher both in C1 and
C2, and lower in C1 × C2. Egg size variation observed within the egg batches
from the homozygous isogenic females indicated the influence of environmental
and/or epigenetic effects during the earliest developmental phases. Compared
to the control, high variation in egg size and hatching rates as well as low
mean egg numbers and developmental rates was observed within the two homozygous
isogenic groups. The significant differences in mean egg size between C1 (5.7
mm2) and C2 (4.4 mm2) were not reflected in the measurements taken during the
later growth phase. In both the homozygous isogenic lines the coefficient of
variation for body length increased from day 6 (mean: 11.7%) until day 80 of
life (mean: 19.0%). As shown by comparably low coefficients of correlation between
measurements the size ranking of individual larvae and fingerlings within C1
and C2 changed during growth.
(Institute of Animal Husbandry and Genetics, University of Göttingen, Albrecht-Thaer-Weg
3, 37075 Göttingen, Germany; email of A. Müller-Belecke:
amuelle5@gwdg.de)
GEOGRAPHICAL ORIGIN OF INDIVIDUAL BREEDERS FROM GILTHEAD SEA BREAM (SPARUS AURATUS)
HATCHERY BROODSTOCKS INFERRED BY MICROSATELLITE PROFILES
Sabina De Innocentiis, Emanuela Miggiano, Andrea Ungaro, Silvia Livi, Luciana
Sola, Donatella Crosetti-2005
Aquaculture 247 (1-4): 227-232
Abstract:
Determination of seed origin is essential for a sustainable use of aquatic resources,
in order to protect local biodiversity in restocking programmes or culture-based
fisheries and as a precautionary approach to mitigate the genetic impact of
accidental escapees from fish farms. Tracking the geographical origin of individual
breeders is also useful to fish farmers, whose information on their own broodstocks
is sometimes fragmentary. Gilthead sea bream (Sparus auratus) broodstocks from
two Italian commercial hatcheries were genetically characterized using four
microsatellite loci. The most likely geographical origin among five natural
populations was inferred for each single breeder through Bayesian statistic-based
methods. Results show a mixed and highly heterogeneous origin of the broodstocks
analysed, and revealed a high percentage of Atlantic individuals among breeders.
(Central Institute for Marine Research (ICRAM), via di Casalotti 300, 00166
Rome, Italy; email of S. De Innocentiis:
s.deinnocentiis@icram.org)
THE RELATIONSHIP OF THE CRYOPROTECTANTS METHANOL AND DIMETHYL SULFOXIDE AND
HYPEROSMOTIC EXTENDERS ON SPERM CRYOPRESERVATION OF TWO NORTH-AMERICAN STURGEON
SPECIES
Ákos Horváth, William R. Wayman, Béla Urbányi, Kent
M. Ware, Jan C. Dean, Terrence R. Tiersch-2005
Aquaculture 247 (1-4): 243-251
Abstract:
Successful sperm cryopreservation techniques have been developed for Eurasian
sturgeon species; however, there is little information available on these techniques
for North-American species. In this study, two sets of sperm cryopreservation
experiments were carried out on the endangered shortnose sturgeon (Acipenser
brevirostrum). In the first set, the cryoprotectants methanol (MeOH) and dimethyl
sulfoxide (DMSO) were investigated using three concentrations (5%, 10% and 15%).
The highest post-thaw motility was found using 5% DMSO (26±13%) while
the use of 5% MeOH resulted in the highest rates for fertilization at the 4-cell
stage (40±15%), neurulation (38±13%) and hatching (32±12%).
In the second set, the Original Tsvetkova's extender (OT), Modified Tsvetkova's
extender (MT) and modified Hanks' balanced salt solution (mHBSS) were investigated
in combination with three MeOH concentrations. The highest post-thaw motility
(18±10%), fertilization (18±11%) and hatching rates (17±12%)
were observed with MT extender used in combination with 5% MeOH. In another
set of experiments, the effects of two extenders (MT and mHBSS) and two concentrations
of MeOH were investigated for sperm cryopreservation of pallid sturgeon (Scaphyrinchus
albus). The highest post-thaw motility (70±10%) was observed using MT
and 10% MeOH while MT and 5% MeOH yielded the highest rates of fertilization
(88±6%) and hatching (73±14%). In general we conclude that although
hyperosmotic conditions of extenders and cryoprotectants result in higher post-thaw
motility, they seem to reduce the fertilizing ability of the sperm.
(Aquaculture Research Station, Louisiana Agricultural Experiment Station, Louisiana
State University Agricultural Center, Baton Rouge, 2410 Ben Hur Road, LA 70820,
USA; email of A. Horvath:
Horvath.Akos@mkk.szie.hu)
COMMUNAL LARVAL REARING OF EUROPEAN LOBSTER (HOMARUS GAMMARUS): FAMILY IDENTIFICATION
BY MICROSATELLITE DNA PROFILING AND OFFSPRING FITNESS COMPARISONS
Knut E. Jørstad, Paulo A. Prodöhl, Tore S. Kristiansen, Maria Hughes,
Eva Farestveit, John B. Taggart, Ann-L. Agnalt, Andy Ferguson-2005
Aquaculture 247 (1-4): 275-285
Abstract:
Stock enhancement experiments of European lobster (Homarus gammarus) have been
carried out around the Kvitsøy Islands in south-western Norway since
1990. In addition to releases of coded wire tagged lobster juveniles (cultured)
and subsequent monitoring of commercial fishery, a lobster hatchery was established
in 1997. Several experiments were made on the communal-rearing approach where
the performance of mixed larval groups (families) was evaluated under identical
conditions. Berried females of wild and cultured origin and their respective
fertilised eggs were screened by using microsatellite DNA profiling involving
a multiplex set of six lobster specific primers, thereby allowing determination
of both parental genotypes. Each female were kept separately during hatching,
and the offspring were later mixed and raised in a communal rearing system.
The early-larval survival was estimated at stage IV (bottom stage), and the
survivors were identified to family and group by microsatellite profiling. Five
different communal experiments were conducted, representing offspring from 65
berried females. Of the surviving larvae, 6.3% could not be assigned to family
due to degraded DNA and no PCR amplification. Significant differences in early
survival between offspring of wild and cultured origin were found in the experiments.
No differences between the groups were found in stage IV larval size. Based
on the pooled data on survival (as a measure of early larvae fitness) offspring
of cultured females displayed a relative fitness of 60% in comparison to offspring
from wild females. Large variation in survival was also observed among families
within the “wild” and “cultured” groups, suggesting
a genetic component for these traits and a potential for selective breeding.
(Department of Aquaculture, Institute of Marine Research, P.O. Box 1870 Nordnes,
5024 Bergen, Norway; email of Knut E. Jørstad:
knut.joerstad@imr.no)
MASS PRODUCTION OF COMPETENT LARVAE OF THE SEA URCHIN LYTECHINUS VARIEGATUS
(ECHINODERMATA: ECHINOIDEA)
Esperanza Buitrago , Cèsar Lodeiros, Karem Lunar, Daniela Alvarado, Federico
Indorf, Khenia Frontado, Pulido Moreno, Zoila Vasquez-2005
Aquaculture International 13 (4): 359 - 367
Abstract :
We evaluated the mass production of competent larvae of the sea urchin Lytechinus
variegatus cultured at three initial densities (0.25, 0.5, and 1 larvae per
ml) and fed Chaetoceros muelleri. Survival, length, dry weight of larvae, and
larval stage index (LSI) were estimated in each treatment as a function of the
density. Density decreased during the experiment due to mortality, but the percentage
was similar in all three treatments (68.5, 66.7, and 76.0%). The experiment
was stopped at 13 days after fertilization, when most of the larvae were competent
and had settled. There were no significant differences in survival (exceeded
65% in all treatments), length and larval stage index among treatments. However,
larvae weight in the two low density treatments (1.1 ± 0.11 mg and 1.2
± 0.05 mg, respectively) was greater than the high density treatment
(0.59±0.376 mg). This study demonstrates that competent larvae of Lytechinus
variegatus can be produced with less than 25% mortality in 13 days when cultures
are started at densities of 0.25–1 larvae/ml. Culturing at higher densities
(0.5–1 larvae/ml) had no apparent disadvantages and would reduce the cost
of production.
(Fundación La Salle de Ciencias Naturales (FLASA), Estación de
Investigaciones Marinas de Margarita (EDIMAR), Porlamar, 6301, Apartaao Postal
144, Isla Margarita, Estado Nueva Esparta, Venezuela; email of Esperanza Buitrago:
ebuitrago@edimar.org)
DEFORMATION OF THE NOTOCHORD BY PRESSURE FROM THE SWIM BLADDER MAY CAUSE MALFORMATION
OF THE VERTEBRAL COLUMN IN CULTURED ATLANTIC COD GADUS MORHUA LARVAE: A CASE
STUDY
Sindre Grotmol, Harald Kryvi, Geir K. Totland -2005
Diseases of Aquatic Organisms 65:121-128
Abstract:
This study describes a malformation that frequently occurs in Atlantic cod Gadus
morhua in intensive culture systems. The malformation is characterised by a
slight upward tilt of the head and an indented dorsal body contour at the transition
between the head and the trunk, and is first evident to the fish farmer when
the cod reach the juvenile stage. These abnormalities are associated with malformations
of the neurocranium, the cranial region of the vertebral column and the cranial
part of the epaxial lateral muscles. The pathogenesis involves deformation of
the notochord, which can be observed in larvae about 7 d post-hatch (dph) and
onwards. The deformation consists of an increase in dorsal curvature of the
notochord in the region above the swim bladder. In the same region, the notochord
has an abnormal cross-sectional outline, characterised by a groove-shaped, longitudinal
impression along the ventral surface of the sheath. In most cases, the swim
bladder fills the impression, and in severely affected larvae it forms a hernia-like
lesion in the notochord. The deformation of the notochord seems to be conveyed
to the vertebral body anlagen (chordacentra), which in teleosts are formed by
mineralisation within the notochordal sheath. The vertebral bodies adopt an
abnormal wedge shape, with a ventral concavity, and the neural arches are most
often S-shaped. A continuous range of degrees of the malformation can be observed.
All these pathomorphological characteristics are compatible with the notion
that the notochord has been subjected to an upward mechanical force, probably
generated by a persistent increase in pressure between the swim bladder and
the notochord during the period of development of the vertebral anlagen. Our
results thus indicate that the critical time window with regard to development
of the malformation is from 18 to 36 dph, when the initial formation of the
vertebrae takes place. Chronic overinflation of the swim bladder or pathological
dilatation of the digestive tract may cause the lesions, and aetiology may be
related to factors that influence the function of these organs.
(Department of Biology, University of Bergen, Allégt. 41, 5007 Bergen,
Norway; email of Sindre Grotmol:
sindre.grotmol@bio.uib.no)
DISSEMINATION OF TRIACTINOMYXONS (MYXOZOA) VIA OLIGOCHAETES USED AS LIVE FOOD
FOR AQUARIUM FISHES
Sascha L. Hallett, Stephen D. Atkinson, Christer Erséus, Mansour El-Matbouli-2005
Diseases of Aquatic Organisms 65:137-152
Abstract:
Freshwater ‘tubifex’ oligochaetes sold as live food for aquarium
fishes were purchased from several pet shops in Munich, Germany, over a 1 yr
period (March 2001 to February 2002). These samples were screened for parasitic
infections of actinosporean myxozoans to gauge the possibility of parasite dispersal
via this route. Of 7 samples, 6 contained infected oligochaetes; waterborne
spores were present in 5 samples at the time of purchase. In the laboratory,
12 different types of actinosporeans were released by the oligochaetes. These
could be assigned to 4 collective groups: triactinomyxon, aurantiactinomyxon,
raabeia and hexactinomyxon; 4 novel triactinomyxons are described herein, a
fifth triactinomyxon has been described earlier. Phenotypic descriptions of
the spores are accompanied by molecular sequence data (18S rDNA). Descriptions
of the other actinosporean types appear elsewhere. The worms sold as ‘tubifex’
originated from eastern European countries and were identified as a mix of Tubifex
tubifex, Limnodrilus hoffmeisteri and L. udekemianus. Sale of live worms (and
their accompanying parasite load) has clearly the potential to facilitate introduction
both of parasites and suitable hosts to new areas.
(Institute of Zoology, Fish Biology and Fish Diseases, University of Munich,
Kaulbachstrasse 37, 80539 Munich, Germany; email of Mansour El-Matbouli:
el-matbouli@lmu.de)
