Arxiu d'etiquetes: catalan coast

The submarine observer

Just as explained in the article “Technology to the rescue of data” the OBSEA platform is an underwater observatory placed on the Catalan coast. The aim of this article is to provide a general description of the observatory, the sensors and a brief comment of the studies and uses that are being done currently.

The platform

The OBSEA (Western Mediterranean Expandable SEAfloor OBservatory) is an underwater observatory designed, deployed and managed by the technologic group SARTI from the Universitat Politècnica de Catalunya (UPC). It is placed 4km off Vilanova i la Geltrú coast at 20m depth, in a fishing protected area, and has an optical fibre cable connecting it to the terrestrial laboratory that provides the required energy for the correct performance of the different sensors and allows a transmission of data from the platform to the lab. Thus the information is received in real time and the problematic related with instrumentation powered by batteries is avoided. Furthermore,  it also allows to the engineers of the SARTI to make software modifications and checkings of the electronic devices with no need of taking out of the water the observatory.

Plataforma OBSEA
OBSEA platform (Image: SARTI-UPC)

Instrumentation and studies

The whole electronic system is installed in a watertight cylinder for protecting it, and the instrumentation connections, from short-circuiting. At the same time, this cylinder is placed inside a metallic structure that protects it from external factors and fixes it to the seabed.

External structure of the OBSEA (3D Image: Renderparty)
External structure of the OBSEA (3D Image: Renderparty)

One of the most important sensors when studding the ocean is the CTD (Conductivity Temperature Depth), it is used in multitude of studies, from biologic to physic. With this device one can get direct information about temperature, conductivity and pressure, and other parameters can be calculated: salinity from conductivity, depth from pressure,…

Video camera with a 360º axis rotation(Image: SARTI-UPC)
Video camera with a 360º axis rotation(Image: SARTI-UPC)

Two video cameras provides images in real time of the observatory surroundings. Meanwhile one has an axis rotation of 360º the other one is fixed in one position. These cameras allow the realization of very different projects, from biologic and behavioural studies of the fauna linked to the observatory and its environment, to projects focused on the citizen participation on the scientific world, through the identification of the species that appear on the images, and are the key factor of a group in Facebook where the users post peculiar images pictured by these cameras and the scientist answer the questions presented.

A hydrophone gets and characterizes acoustically ambient noise and, thanks to a specific software, is a capable of discriminate between biologic and anthropogenic noise. This sensor is currently used by studying the cetaceous of the area and the possible relation between the fish assemblages living around the observatory, the cetaceous (predators) and the maritime transit.

AWAC instal·lat a l'OBSEA (Imatge: SARTI-UPC)
AWAC connected to the OBSEA (Image: SARTI-UPC)
Sismògraf instal·lat a l'OBSEA (Imatge: SARTI-UPC)
Seismograph connected to the OBSEA (Image: SARTI-UPC)

The AWAC is a current profiler and a wave measurement system, it allows the measurement the speed and direction of the water at different depth, from the seabed to the surface. It is also capable of differentiate between different types of waves: long storm waves, short windy waves or waves generated by ship.

The pH sensor gives information of water acidity.

The observatory also has installed a seismograph prepared for detecting any tectonic movement produced anywhere in the planet. The obtained data is checked with a universal database in order of being referenced and verified. This seismograph was capable of detecting, among others, the seismic movements produced during the 2011 Japan earthquake and tsunami or produced for the platform of Castor Project (Catalan coast).

Finally, it is of relevance the extension of the OBSEA, a buoy. This buoy is permanently connected to the observatory and has a complete meteorological station for measuring, among others, air temperature, wind speed and direction, atmospheric pressure,…

Boia oceanogràfica connectada a l'OBSEA
Oceanographic buoy connected to the OBSEA (Image 3D: Renderparty)

The OBSEA platform allows the obtaining of data from many different types (biological, oceanographic, atmospheric,…) and, more important, continuously and in real time. This functionality made the OBSEA a key tool in the development of the actual and future oceanographic studies.

References

Aguzzi J, Mànuel A, Condal F, Guillén J, Nogueras M, Del Río J, Costa C, Menesatti P, Puig P, Sardà F, Toma D and Palanques A (2011). The New Seafloor Observatory (OBSEA) for Remote and Long-Term Coastal Ecosystem Monitoring. Sensors vol. 11, pp: 5850−5872.

OBSEA

Renderparty

SARTI-UPC

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Technology to the rescue of data

The purpose of this article is to show a general vision of the main problems of the traditional sampling techniques and the actual situation and advantages that the modern methods offer. More specific examples will be given in future articles in order to explain the running and some studies that have been using these new techniques.

THE PROBLEM

In science is very important to have a good quality data in order to develop any study and not being criticized by editors and REVISORS of the SCIENTIFIC MAGAZINES. Frequency, number, type and sampling sensors are just the first ones of a long list of important factors that you need to have in mind when planning the sampling of your study. There is no magic trick, each study is different and requires number and sampling frequency… different, specific and optimum.

When you are trying to discover the marine mysteries the problems just get bigger, the accessibility is much more limited than in the terrestrial habitats and you cannot go sampling every time you desire, some days maritime weather conditions difficult sampling and, often, you are forced to cancel it, leaving an important data gap. Traditional sampling methods, even their evolution among the years, requires the presence in situ of the scientist, nowadays we are not using a simple thermometer anymore but a complex CTD that provide a much more precision in multitude of different parameters (depending on the sensors attached at the CTD), at the same time and at the desired depth, but we always need a ship, for going at the selected coordinates, and some operators for raising and lowering the sensor. Moreover, biological sampling traditional techniques (trawling and longlines, among many other fishing arts, as well as direct observations via scuba diving) present another huge problem: they are very invasive methods, not just for the species itself but, many times like with bottom trawling method, for the environment, furthermore, the animals captured usually die during the manipulation process. Notice that, for being invasive methods (nets, ships, scuba divers,…), the correct study of the animals normal behaviour is affected, due to the response of the fish towards these invasive presence.

NEW TECHNOLOGIES

Recently, new different revolutionary sampling methods (Autonomous Underwater Vehicle and Cabled Underwater Observatory) have been implanted in order to reduce the above-mentioned problems. In the two given examples we find a set of sensors, adaptable to the desired study, installed in a small space. While AUV allow an automatic, or remote control, movement towards exact coordinates and, in some cases, are able to send the collected data via satellite, submarine observatories are fixed at the seabed becoming just one more element of the environment and producing no perturbation in the normal behaviour of the animals. Due to the connection via cable they can receive permanently energetic supplying without relying on the batteries duration, and send the collected data at real time. Therefore, the new technologies allow us to increase sampling frequency since the dependency on the climate conditions become much less important unlike the above-mentioned case of the scuba divers. However, the disturbance does not decrease when working with AUV, as well as the complications in studying animal behaviour.

Guanay2, the AUV designed by the technological group SARTI-UPC. Image: SARTI-UPC.
Guanay2, the AUV designed by the technological group SARTI-UPC. Image: SARTI-UPC.

UNDERWATER OBSERVATORIES

Cabled underwater observatories are slowly colonizing the coast around the world either forming big networks or individual observatories.

Nowadays, the more powerful observatories are the Canadian VENUS and NEPTUNE, both of them managed by the Ocean Networks Canada.  The first one was deployed on the 2006 and consists of 3 nodes placed between 100 and 300 meters deep in the Salish Sea, British Columbia, Canada. In addition to its function of studying the oceanographic phenomena it was also used as a test site of what would be its bigger brother, the NEPTUNE. This second network is working since 2009 and consist of 6 nodes and multitude of different sensors distributed on the oceanic profile of the Vancouver Isle west coast, from 23 to 2660 meters deep. For being placed over the fault produced due the interaction between the Juan de Fuca the Nord-American tectonic plate, it is an important observatory for the study of the plate tectonic forces.

NEPTUNE nodes distribution.
NEPTUNE nodes distribution. Autor: NEPTUNE (Creative Commons)

In Europe, we are not lagging behind, the EMSO (European Multidisciplinary Seafloor and Water Column Observatory) has grouped the isolated observatories, either underwater platforms or pelagic buoys, with the objective of forming a multidisciplinary network at European level.

OBSEA

One of the members of this European network is placed in the Catalan Coast, the OBSEA. The OBSEA platform (Western Mediterranean Expandable SEAfloor OBservatory) is a cabled video platform located at 20m depth, 5 km off Vilanova i la Geltrú. It was designed, deployed and managed by the technologic group SARTI from the UPC (Universitat Politècnica de Catalunya), conceived as a platform capable of supporting many different sensors in order to monitor different oceanographic parameters (such as temperature, salinity, seismic waves, tides heigh,…), and is also an instrumentation test site within the EMSO. The observatory is equipped with two video cameras, one fixed and the other with a 360º rotation angle, which can acquire digital images of the environment surrounding the OBSEA and everyone can check those live images from the OBSEA website.

OBSEA platform. Image: SARTI-UPC.
OBSEA platform. Image: SARTI-UPC.

New sampling methods help the researches to get a lot of good quality data for achieving a better understanding of the oceans. Sometimes however, the sampling frequency is so high that the amount of data produced is bigger than can be processed and we have to develop new software capable of working with big volume of data and help us in their manipulation and interpretation.

REFERENCES

  • Aguzzi J, Mànuel A, Condal F, Guillén J, Nogueras M, Del Río J, Costa C, Menesatti P, Puig P, Sardà F, Toma D and Palanques A (2011). The New Seafloor Observatory (OBSEA) for Remote and Long-Term Coastal Ecosystem Monitoring. Sensors vol. 11, pp: 5850−5872.
  • Ona E and Godø OR (1990). Fish reaction to trawling noise: the significance for trawl sampling. Rapports et Procès-Verbaux des Réunions. vol. 189, pp: 159-166.
  • Stoner AW, Ryer CH, Parker SJ, Auster PJ and Wakefield WW (2008). Evaluating the role of fish behavior in surveys conducted with underwater vehicles. Canadian Journal of Fisheries and Aquatic Science. vol. 65, pp: 1230-1243.
  • Thrush SF and Dayton PK (2002). Disturbance to Marine Benthic Habitats by Trawling and Dredging: Implications for Marine Biology.Annual Reviews of Ecology and Systematics. vol. 33, pp: 449-473.
  • OBSEA
  • OCEAN NETWORKS CANADA
  • SARTI-UPC
  • Wikipedia NEPTUNE

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Submarine canyon of Cap de Creus (Catalonia)

In this publication I will explain what is a submarine canyon and, in concret, I will give some details from the submarine canyon of Cap de Creus, in Catalonia.

WHAT IS A SUBMARINE CANYON?

A submarine canyon is a valley placed in the continental platform, formed when the sea level was lower.

SUBMARINE CANYON OF CAP DE CREUS

The submarine canyon of Cap de Creus is 3 km to the coast and it has a length of 40 km and the hightest depth is 1400 m. In the next picture, at the left side we can watch a 2D image of its place and the first part of this canyon, meanwhile in the right side we can see the same part in 3D. Both picture have been obteined with the program ArcGis.

CapCreus-Blog
GIS picture of the submarine canyon of Cap de Creus (Picture: Marc Arenas Camps).

If you want to see a 3D animation, click here: https://www.facebook.com/photo.php?v=147537398783517.

The canyon has a high diversity. The communities presents at 190 metres are very different from the observed at the continental platform. The most characteristic specie is the scleractinian coral Madrepora oculata, a white coral from depths and cold waters, very important for benthic animals and young fishes. For this reason, the experts request for their protection and conservation.

REFERENCES

  • Indemares
  • TARBUCK, E. J i LUTGENS, F. K. Ciencias de la Tierra. Una introducción a la geología física. (Ed. Pearson, 8ª)

Difusió-anglès

Cetaceans in the catalan coast

The goal of this publication is to describe the different cetaceans that live in the catalan coast. At first, I will explain you what is a cetacean and then I will describe them.

INTRODUCTION

Cetaceans are a mammal order that live adapted to swimming and, for this reason, they develop all the activities in the water. Most of them live in the sea, but there are a small group that live in fresh water. This adaptation consists on the presence of hydrodynamic bodies to reduce the resistance and the presence of fins (pectorals, dorsal and caudal fins). Cetaceans, as well as the rest of the mammals, are homeotherms (they have physiological mechanisms to keep a constant temperature of the body, known as warm-blooded). Furthermore, they breath air and, for this reason, their nostrils are dorsal, called blowhole. More or less, there are 80 species of cetaceans, subdivided on: odontoceti (toothed cetaceans, which includes dolphins, porpoises, beluga, narwhal, beaked whales and sperm whales) and mysticti (cetaceans without teeth; which includes whales and fin whales).

8 species live in the coast of Catalonia: common bottlenose dolphin, short-beaked common dolphin, striped dolphin, fin whale, sperm whale, Risso’s dolphin, long-finned pilot whale and Cuvier’s beaked whale.

COMMON BOTTLENOSE DOLPHIN

Common bottlenose dolphin (Tursiops truncatus) is the most typical dolphin in zoos. We can recognise them for the color of their skin: mainly is grey, but the abdomen is lighter. The dorsal fin is convex. This dolphins usually live in groups of 2 – 15 individuals, but sometimes the groups are composed for several hundreds. They are very acrobatic. Common bottlenose dolphin has the global conservation status of “least concern”, but in the Mediterranean Sea is “vulnerable” (UICN).

Imatge
Common bottlenose dolphin (Tursiops truncatus) (Foto: Sheilapic76, Creative Commons).

SHORT-BEAKED COMMON DOLPHIN

Short-beaked common dolphin (Delphinus delphis) is easily recognisable for the color patron. Its back is grey or brown with a V drawing under the dorsal fin. In addition, they have a yellowish patch and a grey patch in the sides that form a typical hourglasse figure. They usually live in groups of 10 – 200 individuals. Like, common bottlenose dolphins, they are good acrobats. They are endangered in the Mediterranean Sea, but in global their category from UICN is “least concern”.

Imatge
Short-beacked common dolphin (Delphinus delphis) (Foto: Jolene Bertoldi, Creative Commons).

STRIPED DOLPHIN

Striped dolphins (Stenella coeruleoalba) have a brown or grey dorsal fin, moderately high; dark and prominent beak, well distinguished from the melon (a lump of fatty tissue that forms the forehead of toothed whales and tht is thought to function as a means of focusing sound for echolocation); and its back is grey or brown, light grey from the center of each side to dorsal fin and in the subsequent part. Moreover, they have a thin dark line from the beak to the lower part of sides. They normally live in groups of 25 – 100 individuals. They are good acrobats too. Striped dolphin is the most abundant cetacean in the North West of the Mediterranean Sea, but its status is vulnerable here.

Imatge
Striped dolphin (Stenella coeruleoalba) (Foto: 20minutos).

FIN WHALE

Fin whale (Balaenoptera physalus) is the biggest cetacean of the catalan coast. Fin whales have a high dorsal fin, placed at last third of the body and a wide and flattened head. Their body is long and dark grey without spots, more lighter in the abdomen. You can’t usually see their caudal fin. Their conservation status is “vulnerable” in de Mediterranean Sea, but is “endangered” in global.

rorqual comú
Fin whale (Balaenoptera physalus) (Foto: UW Today).

SPERM WHALE

Sperm whale (Physeter macrocephalus) is another big cetacean in Mediterranean Sea. The lobes of the tail are wide and triangular, with an important groove; they have an small hump, followed for six protuberances; their head is rounded and represent one third of the body; and their body color is dark grey to brown violet. Their blast is leaning and place a little in the left. They usually swim slowly. Spearm whale is catalogued as “vulnerable” in global for UICN, but in the Mediterranean is “endangered”.

Imatge
Sperm whale (Physeter macrocephalus) (Foto: Advocacy Britannica).

RISSO’S DOLPHIN

Risso’s dolphin (Grampus griseus), known like grey dolphin too, has a high dorsal fin, long sharp pectoral fins, a rounded head with a bulbous melon, a curved mouth and a grey to brown color, with several marks and lighter abdomen. They usually live in groups of 3 – 30 individuals, but sometimes they live in groups of several miles. Their conservation status is “least concern” in general, but there isn’t enough information for Mediterranean.

Imatge
Risso’s dolphin (Grampus griseus) (Foto: El hogar natural).

LONG-FINNED PILOT WHALE

Long-finned pilot whale (Globicephala melas) has a short, wide rounded dorsal fin; high and narrow pectoral fins that mesure a fifth part of the body; a bulbous melon; a short snout; and the color of its body is dark grey, black or brown. They normally live in groups of 10 – 60 individuals. There isn’t enough information to evaluate their conservation status.

Imatge
Long-finned piolt whale (Globicephala melas) (Foto: El hogar natural).

CUVIER’S BEAKED WHALE

Cuvier’s beaked whale (Ziphius cavirostris) is a species with a little surface activity and for this reason is very hard to see it. Its caudal fin has wide lobes, without a central groove or very small and lightly sickle-shaped. The dorsal fin is placed behind the center of the body. The snout is short, curved and cream-coloured. The color of the body is brown reddish to dark grey, with darker abdomen. They usually live in groups of 2 – 7 members, ocasionally untill 25, but older males normally live alone. There isn’t enough information to evaluate their conservation status.

Imatge
Cuvier’s beaked whale (Ziphius cavirostirs) (Foto: Aceytuno).

This are the 8 most tipical species in the coast of Catalonia. I hope that with this small guide you could identify them easily.

REFERENCES

Difusió-anglès