21 research outputs found
Role of Lipid, Protein, Carbohydrate and Nucleic Acid As Indicators of the Moulting Cycle of Norway Lobster (Nephrops norvegicus)
ASLO Summer Meeting 2005, Santiago de Compostela, Spain, 19-24 June 200
Modeled Buoyancy of eggs and larvae of the deep-sea shrimp Aristeus antennatus (Crustacea: Decapoda) in the northwestern Mediterranean Sea
Information on the buoyancy of eggs and larvae from deep-sea species is rare but necessary for 30 explaining the position of non-swimming larvae in the water column. Due to embryonic 31 morphology and ecology diversities, egg buoyancy has important variations within one species and 32 among other ones. Nevertheless, it has hardly been explored if this buoyancy variability can be a 33 strategy for deep-sea larvae to optimize their transport beyond their spawning areas. In the 34 northwestern Mediterranean Sea, protozoea and mysis larvae of the commercial deep-sea shrimp 35 Aristeus antennatus were recently found in upper layers, but to present, earlier stages like eggs and 36 nauplii have not been collected. Using a Lagrangian transport model and larval characteristics, we 37 evaluate the buoyancy and hydrodynamic effects on the transport of A. antennatus larvae in the 38 northwestern Mediterranean Sea. The transport models suggested that 75% of buoyant eggs 39 released between 500 and 800 m depth (i.e., known spawning area), reached the upper water layers 40 (0-75 m depth). Then, according to the modeled larval drifts, three spawning regions were defined 41 in the studied area: 1) the northern part, along a continental margin crossed by large submarine 42 canyons; 2) the central part, with two circular circulation structures (i.e., eddies); and 3) the 43 southern part, with currents flowing through a channel. The number of larvae in the most upper 44 layer (0-5 m depth) was higher if the larval transport model accounted for the ascent of eggs and 45 nauplii (81%) instead of eggs reaching the surface before hatching (50%). The larvae reaching the 46 most water upper layer (0-5 m depth) had higher rates of dispersal than the ones transported below 47 the surface layer (deeper than 5 m depth). The results of larval dispersal simulations have 48 implications for the understanding of A. antennatus larval ecology and for management decisions 49 related to the shrimp fisheries in the northwestern Mediterranean S
Monitoring species in artificial reefs using acoustic communications
The purpose of this work is to study and evaluate the
limitations of using acoustic communications in the vicinity of
artificial reefs. By placing hydrophones and transmitters in
different strategic locations we have studied the performance of
this technology in confined spaces. The ultimate goal of this
work is to provide information for the proper design of acoustic
communication systems to monitor species in artificial reefs.Peer ReviewedPostprint (published version
Creel fishing and acoustic tracking trials in the No-Take zone off Palamós-Roses (Northwester Mediterranean Sea) at 350-420 m depth
Postprint (published version
Development and growth of the early juveniles of the spider crab Maja squinado (Brachyura: Majoidea) in an individual culture system
The spider crab Maja squinado is an endangered Mediterranean species; therefore, culturing it successfully is essential for developing restocking programs. The survival, growth and development of post-larval stages (juvenile crabs, C1-C8) were studied using larvae obtained from adult individuals collected in the Catalan Sea. The juvenile crab stages were cultured individually from a megalopal stage using a semi-open recirculation system to obtain the precise growth data of each juvenile crab stage until C8. Development up to C8 at 20ºC lasted 154±10 days. Survival from C1 to C8 was 5.8 %. Moult increment values in cephothoracic length were similar in all the crab stages (21-35 %). Intermoult duration (9±1 in C1-C2 to 51±8 days in C7-C8) increased sharply from juvenile stage 5. Males and females can be distinguished from C4 based on sexual dimorphism in the pleopods and the presence of gonopores. The allometric growth of the pleon is sex-dependent from C4, with females showing positive allometry and males isometric growth. The juvenile growth rate was lower compared with that of the previously studied Atlantic species Maja brachydactyla
Diversity of Vibrionaceae bacteria isolated from the haemolymph of the spider crab Maja brachydactyla
Aims: The aim of this study was to characterise and identify vibrios isolated
from the haemolymph of apparently healthy adult spider crabs (Maja brachydactyla)
wild-caught in the Spanish localities of Galician coast and in the Canary
Islands and also from captive animals held at IRTA’s facilities in the Ebro
Delta of Catalonia, north-west Spanish Mediterranean coast.
Methods and Results: A total of 277 bacterial isolates were obtained, and of
these, 171 were characterised with rep-PCR, resulting electrophoretic bands
were analysed and clusters formed. Identification of representative strains of
each cluster was made by sequencing the 16S rRNA. Samples from animals
caught in Galicia and captive at IRTA (around 15–18 C) rendered mostly
species belonging to the Splendidus clade (72Æ2 and 76Æ6% respectively),
commonly found in cold waters (below 20 C). Higher species diversity was
found in the haemolymph of the captive animals. In the warmer Canary
Islands waters (around 21 C), the diversity of vibrios is dominated by three
clades, Harveyi (Vibrio core group, 39Æ3%), Orientalis (23Æ2%) and Splendidus
(21Æ4%) with a species diversity that equals that of the colder captive animals.
Conclusions: Differences in the vibrios populations were found in the
haemolymph extracted from animals collected from the three localities. Potential
new species were found, and their description is under way.
Significance and Impact of Study: As with other invertebrates, spider crabs also
contain a diverse population of vibrios. These findings should help researchers
to diagnose when a crab is infected
Sperm Ultrastructure of the Spider Crab Maja brachydactyla (Decapoda: Brachyura)
This study describes the morphology of the
sperm cell of Maja brachydactyla, with emphasis on localizing
actin and tubulin. The spermatozoon of M. brachydactyla
is similar in appearance and organization to other
brachyuran spermatozoa. The spermatozoon is a globular
cell composed of a central acrosome, which is surrounded
by a thin layer of cytoplasm and a cup-shaped nucleus
with four radiating lateral arms. The acrosome is a subspheroidal
vesicle composed of three concentric zones surrounded
by a capsule. The acrosome is apically covered by
an operculum. The perforatorium penetrates the center of
the acrosome and has granular material partially composed
of actin. The cytoplasm contains one centriole in
the subacrosomal region. A cytoplasmic ring encircles the
acrosome in the subapical region of the cell and contains
the structures-organelles complex (SO-complex), which is
composed of a membrane system, mitochondria with few
cristae, and microtubules. In the nucleus, slightly condensed
chromatin extends along the lateral arms, in
which no microtubules have been observed. Chromatin
fibers aggregate in certain areas and are often associated
with the SO-complex. During the acrosomal reaction, the
acrosome could provide support for the penetration of the
sperm nucleus, the SO-complex could serve as an anchor
point for chromatin, and the lateral arms could play an
important role triggering the acrosomal reaction, while
slightly decondensed chromatin may be necessary for the
deformation of the nucleus
Spermatogenesis of the Spider Crab Maja brachydactyla (Decapoda: Brachyura)
This study describes spermatogenesis in a
majid crab (Maja brachydactyla) using electron microscopy
and reports the origin of the different organelles
present in the spermatozoa. Spermatogenesis in M. brachydactyla
follows the general pattern observed in other
brachyuran species but with several peculiarities. Annulate
lamellae have been reported in brachyuran spermatogenesis
during the diplotene stage of first spermatocytes,
the early and mid-spermatids. Unlike previous
observations, a Golgi complex has been found in midspermatids
and is involved in the development of the
acrosome. The Golgi complex produces two types of
vesicles: light vesicles and electron-dense vesicles. The
light vesicles merge into the cytoplasm, giving rise to
the proacrosomal vesicle. The electron-dense vesicles are
implicated in the formation of an electron-dense granule,
which later merges with the proacrosomal vesicle. In the
late spermatid, the endoplasmic reticulum and the Golgi
complex degenerate and form the structures–organelles
complex found in the spermatozoa. At the end of spermatogenesis,
the materials in the proacrosomal vesicle
aggregate in a two-step process, forming the characteristic
concentric three-layered structure of the spermatozoon
acrosome. The newly formed spermatozoa from testis
show the typical brachyuran morphology
Annual variation in the biochemical composition of newly hatched larvae of Maja brachydactyla in captivity
Quality of newly hatched larvae (NHL) of Maja brachydactyla in captivity has been characterized throughout the year to evaluate their availability for mass production. Spawning took place every month and NHL were collected and analyzed to estimate individual dry weight (DW) and proximate biochemical composition (protein, carbohydrate and lipids). Lipid class, fatty acid composition, amino acid profile, mineral and vitamins A, E and C contents were analyzed seasonally. NHL obtained throughout the year are a potential source for aquaculture purposes, since the increment in the relative protein and lipid (especially phospholipids and n-3 PUFA) content might compensate the decrease in DW of larvae hatched from broodstock kept during one year in captivity. However, the decrease in vitamins A and E as well as in certain essential amino acids (Lys, Val, and His) and trace elements (Cu and Fe) of NHL at the end of the year might be indicative of a nutritional deficiency in broodstock diets