Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

The Bay of Biscay, a good feeding environment for the larvae of anchovy, sardine and horse-mackerel

12.09.2008
A PhD thesis, defended at the University of the Basque Country, analyses the nutritional state of the larvae of anchovy, sardine and horse-mackerel, as well as their growth strategy. Its conclusions point to the Bay of Biscay being a good feeding ground for these species.

The anchovy, sardine and horse-mackerel are three species of great commercial interest to the Basque fishing fleet. However, all three have suffered considerable fluctuations in their catches over the last few decades, reaching all time lows at times. This variability in the catches, due in part to the high mortality rate of their larvae, with lower numbers reaching adulthood, generates great uncertainty when trying to plan good fisheries management.

Predation and food availability are the most important factors in the mortality of larvae and this is why they were the target of the PhD thesis that Ms Estibaliz Díaz Silvestre has defended at the University of the Basque Country (UPV/EHU): Condition and biochemical composition of three pelagic larvae in the Bay of Biscay. The research work was led by doctors Fernando Villate Guinea and Jesus Mari Txurruka Argarate of the Department of Plant Biology and Ecology at the University’s Faculty of Science and Technology. Dr. Díaz is a Biology graduate and currently working as a researcher at the AZTI-Tecnalia Foundation. Apart from this foundation, participating in the project within which the PhD thesis was based, was the CSIC of Barcelona, the Instituto Español de Oceanografía and the University of Vigo.

This research was based on the general hypothesis that better-fed larvae grow better and, thereby, undergo less risk of depredation and lack of nutrition. However, the metabolism of the larvae has to reach a balance between the energy devoted to growth and fleeing predators, on the one hand and, on the other, creating reserves of energy to withstand periods when they are needed, such as winter or during metamorphosis. Thus, Dr. Díaz studied, on the one hand, the nutritional environment and state of the larvae during the period of reproduction of the anchovy, sardine and horse-mackerel and, on the other, different strategies of growth adopted by each species in order to achieve this balance.

Well fed larvae

Dr. Díaz’s research was undertaken using six sample surveys (May, June and July 2000, and April, May and June 2001) and carried out off the coast of the City of Donostia-San Sebastian. Her first objective was to describe the nutritional environment inhabited by the larvae of the fishes during the period of maximum reproduction and, to this end, based on the biochemical composition of the seston (the particles on which the larvae feed). The initial hypothesis was that the nutritional environment along the Basque coast was sufficiently rich to enable the survival of the larvae of the anchovy, sardine and horse-mackerel, and the results from the period studied confirmed this.

Apart from the quantity and quality of food available to the fish larvae, Dr. Díaz has analysed their nutritional state. To this end, the analysis was based on the RNA/DNA index, taking into consideration the quantity of RNA present in cells in comparison to DNA. Her conclusion was that the nutritional condition of the three species is good, coinciding with previous studies, observing scant presence of larvae with signs of starvation.

Two different strategies for growth

From the start of the development stage of the anchovy, sardine and horse-mackerel, proteins are their major food component, followed by lipids and carbohydrates. Nevertheless, the temporary patterns of accumulation of these substances are different in the case common to the first two species, both belonging to clupeids, from the horse-mackerel: with the first two, the percentages of proteins and RNA growth reaching a threshold, while the percentage of lipids and carbohydrates drop reaching a specific minimum for each species (anchovy or sardine). On the other hand, the horse-mackerel shows highly variable percentages during the first stages of growths, that stabilise at later stages, and reach values similar to those of other species.

According to Dr. Díaz, these differences in the biochemical composition of the species could be due to the different growth strategies adopted by each. The anchovy and the sardine, being larvae with anguiliform morphology (elongated), need to grow more rapidly at early stages than the horse-mackerel and, thus, their metabolism is given over to accumulating proteins to form muscle. The larva of the horse-mackerel, on the other hand, is like a tadpole; it swims better than a clupeid larva of the same size — thus enabling it to flee predators more easily — and it has a bigger mouth to capture more and bigger prey.

The conclusions of this PhD defended at the UPV/EHU state that, although initially both groups accumulate nutrients in different proportions, both anchovy and sardine and the horse-mackerel finally coincide with the same the biochemical composition. Dr. Díaz believes that if other species of larvae are studies, these proportions will not differ much from those found in the study, as the patterns of growth and development follow the rigorous rules dictated by natural selection and the biochemical composition of the larvae only means a variation of these patterns.

Dr. Díaz also states that it would be advisable to measure the changes in the biochemical composition of the anchovy, sardine and horse-mackerel in other locations and under different environmental conditions, in order to confirm or otherwise the existence of two different strategies of growth for the two morphological groups studied.

Lucía Álvarez | alfa
Further information:
http://www.elhuyar.com
http://www.basqueresearch.com/berria_irakurri.asp?Berri_Kod=1865&hizk=I

More articles from Life Sciences:

nachricht Cryo-electron microscopy achieves unprecedented resolution using new computational methods
24.03.2017 | DOE/Lawrence Berkeley National Laboratory

nachricht How cheetahs stay fit and healthy
24.03.2017 | Forschungsverbund Berlin e.V.

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Giant Magnetic Fields in the Universe

Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.

The results will be published on March 22 in the journal „Astronomy & Astrophysics“.

Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...

Im Focus: Tracing down linear ubiquitination

Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.

Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...

Im Focus: Perovskite edges can be tuned for optoelectronic performance

Layered 2D material improves efficiency for solar cells and LEDs

In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...

Im Focus: Polymer-coated silicon nanosheets as alternative to graphene: A perfect team for nanoelectronics

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...

Im Focus: Researchers Imitate Molecular Crowding in Cells

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International Land Use Symposium ILUS 2017: Call for Abstracts and Registration open

20.03.2017 | Event News

CONNECT 2017: International congress on connective tissue

14.03.2017 | Event News

ICTM Conference: Turbine Construction between Big Data and Additive Manufacturing

07.03.2017 | Event News

 
Latest News

Argon is not the 'dope' for metallic hydrogen

24.03.2017 | Materials Sciences

Astronomers find unexpected, dust-obscured star formation in distant galaxy

24.03.2017 | Physics and Astronomy

Gravitational wave kicks monster black hole out of galactic core

24.03.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>