Conference PaperPDF Available

THE SEAFLOOR OBSERVATORY OF THE UNDERWATER BIOTECHNOLOGICAL PARK OF CRETE

Authors:

Abstract and Figures

The seafloor observatory of the Underwater Biotechnological Park of Crete (UBPC), is a pioneer singular installation deployed at a depth of 20 m in a special designated coastal area of 25.000 m 2 located in Gournes, Heraklion Crete. UBPC is a large scale research facility of the Institute of Marine Biology, Biotechnology and Aquaculture (IMBBC) of the Hellenic Centre for Marine Research (HCMR) aiming at hosting a large spectrum of experimental and demonstrational Research & Development activities. Specific emphasis is given to applied research for the protection and integrated management of the coastal environment, the sustainable exploitation of marine biological resources and the long-term coastal ecosystem monitoring. The seafloor observatory is a multiparametric platform equipped with oceanographic sensors for the continuous measurement of sea temperature, salinity, density, sound velocity (CTD), in-vivo chlorophyll-a, turbidity, fluorescence (Fluorometer), sea currents velocity/direction in the water column and waves velocity and height (bottom moored ADP). Coupled with the physical oceanography data real-time meteorological measurements of temperature, humidity, wind speed and direction, barometric pressure, precipitation, total solar radiation, Photosynthetically Active radiation (PAR), UVA – UVB radiation are taken from a meterological station established at the IMBBC land premises. The coupled ocean-atmosphere measurements offer the ability to measure and model the connectivity between atmospheric and marine ecosystems at high resolution and over extended periods of time giving new insights into biological, chemical, and physical processes of the local coastal environment.
Content may be subject to copyright.
6
th
International Conference on “Experiments/Process/System Modelling/Simulation/Optimization”
6
th
IC-EpsMsO
Athens, 8-11 July, 2015
© IC-EpsMsO
THE SEAFLOOR OBSERVATORY OF THE UNDERWATER
BIOTECHNOLOGICAL PARK OF CRETE
Dimitrios N. Androulakis
1,2
, Costas G. Dounas
1
, and Dionissios P. Margaris
2
1
Institute of Marine Biology, Biotechnology & Aquaculture, Hellenic Centre for Marine Research, Gournes
Pediados, P.O. Box 2214, 71003 Heraklion, Crete, Greece, webpage: http://www.imbbc.hcmr.gr
2
Fluid Mechanics Laboratory, Mechanical Engineering and Aeronautics Department, University of Patras, GR-
265 04 Patras, Greece, web page: http://www.mead.upatras.gr
Keywords: underwater park, seafloor observatory, current velocity, salinity, coastal management, long-term
monitoring
Abstract. The seafloor observatory of the Underwater Biotechnological Park of Crete (UBPC), is a pioneer
singular installation deployed at a depth of 20 m in a special designated coastal area of 25.000 m
2
located in
Gournes, Heraklion Crete. UBPC is a large scale research facility of the Institute of Marine Biology,
Biotechnology and Aquaculture (IMBBC) of the Hellenic Centre for Marine Research (HCMR) aiming at
hosting a large spectrum of experimental and demonstrational Research & Development activities. Specific
emphasis is given to applied research for the protection and integrated management of the coastal environment,
the sustainable exploitation of marine biological resources and the long-term coastal ecosystem monitoring. The
seafloor observatory is a multiparametric platform equipped with oceanographic sensors for the continuous
measurement of sea temperature, salinity, density, sound velocity (CTD), in-vivo chlorophyll-a, turbidity,
fluorescence (Fluorometer), sea currents velocity/direction in the water column and waves velocity and height
(bottom moored ADP). Coupled with the physical oceanography data real-time meteorological measurements of
temperature, humidity, wind speed and direction, barometric pressure, precipitation, total solar radiation,
Photosynthetically Active radiation (PAR), UVA – UVB radiation are taken from a meterological station
established at the IMBBC land premises. The coupled ocean-atmosphere measurements offer the ability to
measure and model the connectivity between atmospheric and marine ecosystems at high resolution and over
extended periods of time giving new insights into biological, chemical, and physical processes of the local
coastal environment.
1 INTRODUCTION
All notable Mediterranean civilizations were closely connected with their surrounding coastal zones. The
coastal zone has always served as a trading path, a common recreational option and an endless resources deposit
- from fisheries and aquaculture to harvesting energy and mining. Today, integrated coastal management (ICM)
and development is a rather new field for many scientific disciplines such as marine biology, maritime and
coastal engineering and economy, as tourism, fishing and aquaculture remain dynamic marine industries with
major economic impact on coastal ecosystems.
Understanding the complex interactions between the physical, biological, chemical, and geological marine
systems is a challenge for the opening decades of the 21st century. The establishment of a global network of
seafloor observatories is expected to provide the means to accomplish this goal. In Europe the effort to build an
open ocean seafloor observation infrastructure has been supported by the EC (European Commission) first
through ESONET - NoE (European Seas Observatory NETwork - Network of Excellence)
[1]
, aimed at gathering
together the community interested in multidisciplinary ocean observatories
and more recently with the EMSO -
PP project (European Multidisciplinary Seafloor Observatory - Preparatory Phase) aimed at establishing the
legal entity charged of the construction and management of the EMSO infrastructure
[2]
. Similarly, within
JERICO project (Towards a Joined European Research Infrastructure network for Coastal Observatories)
[3]
long-term in situ observations are also acquired from various European coastal areas and the involved scientists
got together in a consortium in order to harmonize the existing coastal infrastructures from the sensors to the
data diffusion (www.jerico-fp7.eu). Since 2006 the Hellenic Centre for Marine Research (HCMR) participates
continuously in all these large scale European research initiatives.
In 2007, HCMR acquired from the Greek State a coastal marine area for the establishment of an Underwater
Biotechnological Park located only 1400 m from the premises of the Institute of Marine Biology, Biotechnology
and Aquaculture (IMBBC) in Crete. The major aim of this project is the establishment of a large-scale facility
for the development of a wide spectrum of experimental and demonstrational activities of both basic and applied
Dimitrios N. Androulakis, Costas G. Dounas, and Dionissios P. Margaris.
marine research and technology. Specific emphasis is given to applied research in the field of artificial reefs
technology and the development and promotion of innovative aspects for marine tourism in relation to artificial
reef technology, the sustainable development of marine biological resources, the protection and integrated
management of the coastal environment and the long-term intense monitoring of local climatic, hydrographic
and environmental coastal parameters. The aim of this paper is to present the Seafloor Observatory of the
Underwater Biotechnological Park of Crete (UBPC) of HCMR, the technical specifications and settings of the
deployed instruments and the first set of the measured data series.
2 THE UNDERWATER BIOTECHNOLOGICAL PARK OF CRETE (UBPC)
2.1 Location and characteristics
The Underwater Biotechnological Park of Crete (UBPC) is established in an exposed to the wave action
seabed area of 25.000 m
2
, located approximately 1,5 km north-west of the HCMR facilities in Gournes,
Heraklion, Crete. The depth of the sea water varies between 18 to 22 meters, increasing towards the northern
direction. The UBPC has been created in order to play a key-role in applied research for the protection and
integrated coastal zone management of the local environment, the sustainable exploitation of marine biological
resources around Crete and the long-term local ecosystem monitoring. Monitoring activities within the UBPC
have started only in May 2014 with the deployment of the seafloor observatory.
Figure 1. Location of the Underwater Biotechnological Park of Crete
Figure 2. Location of the seafloor observatory and the land-based research facilities of HCMR in Crete
(Thalassokosmos)
2.2 The Seafloor Observatory
The Seafloor Observatory is a truss construction made of stainless steel, designed to withstand the marine
environment not only from chemical perspective (inox 316), but also from mechanical (trawl-resistant design).
The Seafloor Observatory was assembled in the land premises of HCMR in Crete and was deployed with the
R/V Filia. Since its deployment, it is constantly inspected by members of the scientific diving group of HCMR
and the scientific instruments are retrieved bimonthly to download their collected data, to charge their batteries
Dimitrios N. Androulakis, Costas G. Dounas, and Dionissios P. Margaris.
for the next deployment and to apply the scheduled maintenance and calibration. If weather conditions allow,
this procedure lasts for less than 24 hours, thus ensuring a consistent time series of oceanographic data.
Figure 3. The seafloor observatory of the UBPC. The bottom-moored truss with the deployed instruments is
presented: 1) the SonTek ADP transducers head , 2) the memory/battery pack of the SonTek ADP, 3) the SAIV
SD208 CTD, and 4) the C3 Turner Designs Submersible Fluorometer
2.3 The Deployed Instruments
The seafloor observatory consists three autonomous power instruments. A SAIV SD208 CTD (Conductivity,
Temperature, Density), a SonTek ADP (Acoustic Doppler Profiler) and a Turner Designs C3 Submersible
Fluorometer. The technical specifications of the instruments are given in Table 1. Each instrument has a different
battery capacity and sampling interval. The CTD takes a measurement every five minutes, while the ADP and
the Fluorometer take a measurement every ten minutes and every six hours respectively. The sampling rate of
each instrument was defined concerning its battery capacity and the time resolution of each physical property
being measured.
The CTD
[4]
has sensors for conductivity, temperature, water pressure, and dissolved oxygen. The
conductivity sensor is an integrated part of the upper end of the instrument. It is an inductive type sensor
consisting of a primary and a secondary coil centered around a quartz liner tube. The liner is used to obtain a
defined water volume. The primary coil induces an electromagnetic field which drives iones through the water
inside the liner in proportion with the water conductivity. The ionic flow is measured by the secondary coil and
this measurement is scaled and expressed in mS/cm (mmho/cm) by the instrument. The conductivity sensor is
fully compensated for temperature and pressure effects.
The temperature is measured by a thermistor. The thermistor resistance Rt depends on the surrounding
temperature, thus allowing the calculation of temperature by simple equations. Fast response is obtained by
mounting the thermistor element in a heat conductive compound inside a silver tip at the top of a stainless steel
prong. The prong extends approximately 17mm off the instrument body. The base of the prong is made of
material with low heat conductivity. By this combination of material properties a time constant of less than 0.5 s
is obtained.
The pressure sensor is based on a Keller PA9 absolute pressure sensor element, which is embedded in the
instrument body. A protective cap with a small hole in the centre (pressure port) covers the diaphragm of the
sensor. The sensor is a piezoresistive type. The resistors form a Wheatstone bridge with output signal
proportional to the applied pressure. The sensing element is basically temperature sensitive, and a set of
individually calibrated temperature coefficients are used to perform a highly accurate compensation according to
a built-in algorithm. The sensor measures the absolute pressure (atmospheric pressure plus water pressure). To
obtain recording of net water pressure, the instrument measures and stores the first pressure measurement each
time a new series is started, and this value is deducted from all the subsequent pressure measurement in that
series. Since the first measurement is the air pressure at surface level, the subsequent recorded pressure data will
be the net water pressure.
Furthermore, using the MiniSoft SD200W accompanying software, more physical properties are derived,
following the UNESCO formularies of the Technical Papers in Marine Science. Salinity is calculated from the
collected data of conductivity, temperature and depth and is expressed in ppt. The depth in meters is calculated
from the measured pressure and temperature, salinity and gravity at the position. The gravity is derived from the
latitude. If the position is not known the software will use nominal gravity 9.80665 m/s
2
. The CTD instrument is
Dimitrios N. Androulakis, Costas G. Dounas, and Dionissios P. Margaris.
set to calculate and record sound velocity, by using the measured conductivity, temperature and pressure data in
according to equations given by Chen and Millero in 1970.
The additional oxygen sensor is based on a sensing element from OxyGuard, the Ocean DO Probe, and is
furnished with a breathing hole for pressure compensation to water depth down to 2000 meters. The sensor uses
silver as cathodic material and pure zinc as anodic material. When combined with the supplied electrolyte, the
sensor generates a polarisation voltage which attracts dissolved oxygen to the cathode through a membrane. In
operation, dissolved oxygen from the water diffuses through the membrane to the cathode. This causes electrons
(current) to flow between the anode and the cathode via an external circuit. The output signal is proportional to
the oxygen saturation (%). In order to make the oxygen reading independent of temperature, the instrument
measures the membrane temperature and compensates for the effect. The recorded data represent the degree of
saturation in %, with the CTD MINISOFT SD200W Software data both in degree saturation and in mg/l units,
compensated for salinity and pressure, can be exported.
The CTD is set with a sampling interval of five minutes and in STDOxc mode, in order to measure and
record salinity, temperature, depth, pressure, sound velocity and dissolved oxygen.
The SonTek ADP
[5]
is monostatic as the same transducer is used as transmitter and receiver. The transducer
is designed to generate a narrow beam of sound at a known frequency. As the sound travels through the water, it
is reflected in all directions by particulate matter (sediment, small organisms, bubbles). Some portion of the
reflected energy travels back along the transducer axis. It is received by the ADP, which measures the change in
frequency of the received signal. The Doppler shift measured by a single transducer reflects the velocity of the
water along the axis of its acoustic beam. The time since the pulse was transmitted determines how far the pulse
has traveled, and specifies the location of the particles that are the source of the reflected signal. By measuring
the return signal at different times, the ADP measures the water velocity at different distances from the
transducer. The profile of water velocity is divided into range cells, where each cell represents the average of the
return signal for a given period. For example, a 1-m range cell corresponds to an averaging time during which
the range to the measurement volume moves one meter.
To measure temperature, the ADP uses a thermistor mounted on the inside of the transducer head. The
thermistor is mounted in a counter-bore hole on the inside of the transducer head, very close to the exposed
surface (to minimize the insulating effects of the plastic case). The temperature sensor has a specified accuracy
of 0.1°C, which is more than sufficient for sound speed measurements. Temperature data are sampled once per
second during the averaging interval; mean and standard deviation of these samples are recorded with each
profile.
A strain gage pressure is mounted in a recessed hole on the top of the transducer head. The pressure sensor is
connected to a small printed circuit board mounted on the back of the ADP processor (Stand-Alone ADP).
The ADP includes an internal compass/tilt sensor to measure the orientation of the ADP. This allows the
ADP to rotate velocity data from the XYZ coordinate system to an Earth (East-North-Up or ENU) coordinate
system independent of ADP orientation.
For the deployment of the ADP the sampling interval is ten minutes and the averaging interval is one minute.
The cell size and the blanking distance are selected at one meter and the number of cells is 24, in order to
calculate wave characteristics -wave data are collected every fourth current profile.
The C3 Submersible Fluorometer
[6]
is manufactured with three optical sensors ranging in wavelengths from
deep ultraviolet to infrared. The specific instrument comes with an in-vivo Chlorophyll sensor, a Turbidity
sensor and a Fluorescein sensor. Each optical sensor is designed with fixed excitation and emission filters. The
C3 Submersible Fluorometer comes with a factory installed temperature probe and is configured with a pressure
sensor for depth measurements up to 600 meters and a mechanical wiper to minimize biofouling. Optional
temperature compensation allows the C3 to compensate for changes in fluorescence due to varying temperatures
as detected by the C3’s temperature sensor. Temperature compensation is available for the in-vivo Chlorophyll
sensor. Pressure compensation is calculated for gravitational variations with latitude, according to the UNESCO
Technical Papers in Marine Science, in order to extract the depth data value. The C3 Submersible Fluorometer
Windows-based user interface allows easy calibration of each sensor, digital data reporting, data logging and
digital or analog export of data.
The sampling interval of the C3 Submersible Fluorometer is set at six hours, (01:00, 07:00, 13:00, 19:00) and
the mechanical wiper makes a full rotation before each measurement, to clean the optical sensors. In addition,
around the optical sensors a thin copper anti-fouling tape is installed, according to the manufacturers
specifications.
In general, all the precautions for corrosion protection have been taken. By their manufacturers the
instruments sensors are mounted either in plastic or in aluminum anodized housings. Furthermore, many zinc
sacrificial anodes are installed all over the truss construction and close to sensitive parts of the instruments like
the ADP transducers head.
Dimitrios N. Androulakis, Costas G. Dounas, and Dionissios P. Margaris.
Instrument Specifications Sampling
Interval
CTD SAIV SD208
Conductivity range: 0-80 mS/cm (res. 0.00008, acc. +/- 0.003)
Temperature range: -2 to 40
o
C (res. 0.0002
o
C, acc. +/- 0.003
o
C)
Pressure range: up to 6000m (res. 0.01 dbar (m), acc. +/-0.01% FS)
Additional Oxygen sensor, OxyGuard Ocean DO Probe: -5 to 45
o
C, up
to 200 bar pressure (res. 0.01 mg/l, acc. +/-0.2mg/l)
Deployment parameters: STDOXc mode, memory sufficient for 200
days
5 min
ADP SonTek
3 transducers of 1000 kHz acoustic beams, with 25
o
slant angle
Velocity range +/- 10 m/s up to 100 range cells, (res. 0.1 cm/s, acc. +/-
1% of measured velocity, +/- 0.5 cm/s)
Compass and tilt sensor (res. 0.1
o
, heading acc. +/- 2
o
, pitch/roll acc. +/-
1
o
)
Temperature and pressure sensor
Wave Recording option
Upward, downward and horizontal configurations, profiling range up to
180 m
Deployment parameters: Bottom-moored deployment, 10 min profiling
interval, 1 min averaging interval, 1 m cell size, 1 m blanking distance,
number of cells: 24, battery sufficient for 200 days of deployment
10 min
Fluorometer
Turner Designs C3
Temperature range: -2 to 50
o
C (res. 0.1
o
C, acc 0.5
o
C)
Depth range: 0 to 600m
In vivo Chlorophyll a: (sens. 0.025μg/L, range 0-500μg/L)
Fluorescein: (sens. 0.001 ppb, range 0-500 ppb)
Turbidity: (sens. 0.05 NTU, range 0-3000 NTU)
Deployment parameters: mechanical wiper for optical sensors, battery
sufficient for 60 days of deployment
6 hours
Table 1. Technical specifications and deployment parameters of the instruments of the seafloor observatory
3 DATA PRESENTATION
The first data set from the CTD temperature measurements from June 2014 to April 2015 is given in Figure
4. A decrease of temperature since early September is observed reaching minima at February and then increases
again. Maximum temperatures were recorded during August. The data from the CTD were in absolute agreement
with the temperature data of the other instruments (ADP, C3) as well as with data collected with a HOBO
temperature sensors vertical array deployed close to the seafloor observatory sensors. Only the CTD data instead
of the ADP or the C3 Submersible Fluorometer data, are presented here due to their much shorter measurement
time interval (5 min).
In Figure 5, CTD salinity data from June 2014 to April 2015 are given. During this period coastal water
salinity presents very small value variations as expected. The fluctuations observed in the right part of the figure
curve (wet period) will be examined in depth alongside with the atmospheric meteorological data and especially
rainfall in due time.
Dimitrios N. Androulakis, Costas G. Dounas, and Dionissios P. Margaris.
Figure 4. Seawater Temperature near the seafloor as measured by the CTD
Figure 5. Seawater Salinity near the seafloor as measured by the CTD
Figure 6 presents the velocity magnitude as recorded from the ADP towards the east-west axis, with positive
values indicating the direction to the East, and negative the direction to the West. For the purposes of this paper,
only data from the first measurement cell are depicted. These measurements are taken less than 2.5 meters above
the seafloor - the ADP transducers stand less than 1.5 meter at the top of the bottom-moored truss and the
blanking distance of the instrument is set to 1 meter. The horizontal axis presents time in months and the vertical
axis presents velocity magnitude in cm/s. A trend with more frequent velocity magnitudes from the West to the
East is noticable as expected due to the local prevailing atmospheric conditions (north, north-west winds) and
their interaction with the dominant coastal current direction (parallel to the shoreline).
Figure 6. Velocity magnitude towards the east-west axis, as recorded by the ADP in the first measurement cell, 2
meters above the seafloor
Figure 7 presents the velocity magnitude towards the north-south direction, with positive values referring to
north direction and negative to south direction. Again all the data values are measured in the first measuring cell
Dimitrios N. Androulakis, Costas G. Dounas, and Dionissios P. Margaris.
(a bit less than 2.5 meters above the seafloor). The horizontal axis presents date values in months and the vertical
axis presents velocity magnitude in cm/s. There is a small predominance of north-facing current direction, but
with small variation from the south-facing direction.
Figure 7. Current Velocity magnitude towards the north-south axis, as recorded by the ADP in the first
measurement cell, 2 meters above the seafloor
The Up-Down velocity magnitude is not presented here since it is almost negligible with average values less
than 1 cm/s, at least in the first measurement cell.
In Figure 8 the current velocity direction, as it is measured and calculated by the ADP transducers in the first
measurement cell -2.5 meters above the seafloor is depicted. A trend line is added in this graph aiming to present
the most common conditions. It is obvious that the current direction trends towards East, East South-East as it
was expected concerning the local prevailing North and North-West winds and the shoreline parallel to the East-
West axis.
Figure 8. Current Velocity direction, as recorded by the ADP in the first measurement cell, 2 meters above the
seafloor
Any discontinuity in the data presented from the instruments-especially in mid December- is due to the local
weather conditions that hardly allowed the instruments to be recovered from the seafloor, but prevented the
diving team from redeploying them for a period of eight days.
Dimitrios N. Androulakis, Costas G. Dounas, and Dionissios P. Margaris.
4 CONCLUSIONS
The stand - alone seafloor observatory deployed by HCMR in the Underwater Biotechnological Park of Crete
addresses its scientific objectives in increasing our knowledge on the very low-frequency processes in terms of
physical and biological parameters occurring on the wave-dominated inner shelf of the northern coasts of Crete.
Major research priorities of this multiparametric platform include the support of a large spectrum of
experimental and demonstrational R&D activities. Specific emphasis is given to applied research for the
protection and integrated management of the coastal environment, the sustainable exploitation of coastal
biological resources, applied research in the field of artificial reef technology and the promotion of innovative
aspects of marine ecotourism such as the construction of recreational diving parks in relation to artificial habitat
technologies. In the future, we are expected to be able to identify and quantify changes in environmental
parameters and to provide information for the analysis of climate-change impacts and the improvement of the
integrated management of this specific coastal area. However, the coastal observatory is still far from delivering
data and information in a format that fully meets the needs of the end-users. Issues of data archiving and quality
assurance remain challenges to be resolved. As the first operational year has been already completed the
evaluation of various technical options that will provide real-time image and data from the seafloor have started
to be considered. The deployment of a cable composed of various single-mode optical fibers and a central copper
conductor tube for the continuous transmission of data and power from and to the deployed instruments is
planned for the end of 2016. The ability to get real-time data from the seafloor is expected to make a major
contribution for the long term monitoring of the local coastal ecosystem and will offer support to relevant
education activities focused on the advanced understanding of marine science and technology as well as to the
implementation of Citizens’ Science projects.
ACKNOWLEDGEMENTS
This study was co-financed by the Hellenic Republic and the European Union-European Regional
Development Fund, in the context of the O.P. Competitiveness & Entrepreneurship (OPCII) and the R.O.P.
Crete of the NSRF, within the framework of the Action entitled «Proposals for Development of Research
Bodies-KRIPIS: IMBBC Marine Biology, Biotechnology & Aquaculture». We thank N. Spyridakis for technical
assistance, the scientific diving team of IMBBC and especially T. Dailianis and J. Glabedakis and finally the
captain M. Kokos and the crew of R.V. Philia for practical support in the initial deployment of the instruments.
REFERENCES
[1] Priede, I.G., Person, R., Favali, P. (2005), “European seafloor observatory network”, J. Sea
Technology, Vol. 46, pp. 45–49.
[2] Favali P. & Beranzoli, L. (2006), “Seafloor observatory science: A review. Annals of Geophysics”, Vol.
49(2-3), pp. 515-567.
[3] Favali, P., L. Beranzoli, M. Best, and EMSO Partners (2014), “EMSO—The European Multidisciplinary
Seafloor and Water-Column Observatory: Transition from planning to implementation”, Proceedings of Oceans
2014 -TAIPEI Conference, IEEE, 7-10 April 2014, Taipei Taiwan, pp 1-6
[4] SonTek/YSI (September, 2000), Acoustic Doppler Profiler Technical Documentation, San Diego, CA, USA.
[5]SAIV A/S (April 2009), Operating Manual for STD/CTD model SD204 with Sound Velocity and Optional
Sensors, Bergen, Norway.
[6] Turner Designs (June, 2012), C3 Submersible Fluorometer User's Manual, Sunnyvale, CA, USA.
... The Cretan Sea (NE Mediterranean), as part of the South Aegean ecoregion, has been characterized as strongly oligotrophic with limited primary productivity [8,9], high salinity (often exceeding 39 PSU), and temperatures ranging from 14 to 28 • C throughout the year [10,11]. Artificial habitats with several heterogenous microhabitats and structural refugia can attract various benthic and benthopelagic organisms [12]. ...
... It comprises a seafloor area of 2.5 ha at a depth increasing from 18 to 22 m along the south-north direction ( Figure 1) [12,22]. The seawater temperature at the area of the UBPC ranges from 14 to 28 • C over the year, while the salinity is relatively stable at 39 PSU, except for occasional dropdowns during the rainy season (November-April); the main current has a west to east direction due to prevailing NNW winds [11]. The seafloor area is characterized by a rather flat relief, intermixing coarse sand flats, and dead Posidonia oceanica matte, with a macroalgal cover mainly of Caulerpa prolifera. ...
Article
Full-text available
The colonization of artificial structures by benthic organisms in the marine realm is known to be affected by the general trophic patterns of the biogeographical zone and the prevailing environmental traits at the local scale. The present work aims to present quantitative data on the early settlement progress of macrofaunal benthic assemblages developing on artificial reefs (ARs) deployed at the Underwater Biotechnological Park of Crete (UBPC) in the oligotrophic Eastern Mediterranean. Visual census and subsequent image analysis combined with scraped quadrats were used to describe the establishment of the communities and their development over three consecutive campaigns, spanning 5 years post-deployment. Macroalgae consistently dominated in terms of coverage, while sessile invertebrates displayed different patterns over the years. Polychaeta and Bryozoa were gradually replaced by Cnidaria, while Porifera and Mollusca displayed an increasing trend over the years. Motile benthos was mainly represented by Mollusca, while the abundance of Polychaeta increased in contrast to that of Crustacea. For both sessile and motile assemblages, significant differences were observed among the years. The results of this study indicate that ecological succession is still ongoing, and further improvement in the monitoring methodology can assist towards a more accurate assessment of the community composition in complex AR structures.
Article
Full-text available
The ocean exerts a pervasive influence on Earth’s environment. It is therefore important that we learn how this system operates (NRC, 1998b; 1999). For example, the ocean is an important regulator of climate change (e.g., IPCC, 1995). Understanding the link between natural and anthropogenic climate change and ocean circulation is essential for predicting the magnitude and impact of future changes in Earth’s climate. Understanding the ocean, and the complex physical, biological, chemical, and geological systems operating within it, should be an important goal for the opening decades of the 21st century. Another fundamental reason for increasing our understanding of ocean systems is that the global economy is highly dependent on the ocean (e.g., for tourism, fisheries, hydrocarbons, and mineral resources) (Summerhayes, 1996). The establishment of a global network of seafloor observatories will help to provide the means to accomplish this goal. These observatories will have power and communication capabilities and will provide support for spatially distributed sensing systems and mobile platforms. Sensors and instruments will potentially collect data from above the air-sea interface to below the seafloor. Seafloor observatories will also be a powerful complement to satellite measurement systems by providing the ability to collect vertically distributed measurements within the water column for use with the spatial measurements acquired by satellites while also providing the capability to calibrate remotely sensed satellite measurements (NRC, 2000). Ocean observatory science has already had major successes. For example the TAO array has enabled the detection, understanding and prediction of El Niño events (e.g., Fujimoto et al., 2003). This paper is a world-wide review of the new emerging “Seafloor Observatory Science”, and describes both the scientific motivations for seafloor observatories and the technical solutions applied to their architecture. A description of world-wide past and ongoing experiments, as well as concepts presently under study, is also given, with particular attention to European projects and to the Italian contribution. Finally, there is a discussion on “Seafloor Observatory Science” perspectives.
Article
Full-text available
The ocean exerts a pervasive influence on Earth’s environment. It is therefore important that we learn how this system operates (NRC, 1998b; 1999). For example, the ocean is an important regulator of climate change (e.g., IPCC, 1995). Understanding the link between natural and anthropogenic climate change and ocean circulation is essential for predicting the magnitude and impact of future changes in Earth’s climate. Understanding the ocean, and the complex physical, biological, chemical, and geological systems operating within it, should be an important goal for the opening decades of the 21st century. Another fundamental reason for increasing our understanding of ocean systems is that the global economy is highly dependent on the ocean (e.g., for tourism, fisheries, hydrocarbons, and mineral resources) (Summerhayes, 1996). The establishment of a global network of seafloor observatories will help to provide the means to accomplish this goal. These observatories will have power and communication capabilities and will provide support for spatially distributed sensing systems and mobile platforms. Sensors and instruments will potentially collect data from above the air-sea interface to below the seafloor. Seafloor observatories will also be a powerful complement to satellite measurement systems by providing the ability to collect vertically distributed measurements within the water column for use with the spatial measurements acquired by satellites while also providing the capability to calibrate remotely sensed satellite measurements (NRC, 2000). Ocean observatory science has already had major successes. For example the TAO array has enabled the detection, understanding and prediction of El Niño events (e.g., Fujimoto et al., 2003). This paper is a world-wide review of the new emerging “Seafloor Observatory Science”, and describes both the scientific motivations for seafloor observatories and the technical solutions applied to their architecture. A description of world-wide past and ongoing experiments, as well as concepts presently under study, is also given, with particular attention to European projects and to the Italian contribution. Finally, there is a discussion on “Seafloor Observatory Science” perspectives.
Conference Paper
EMSO (http://www.emso-eu.org) is a large-scale European Research Distributed Infrastructure (RI) of the ESFRI roadmap composed of fixed-point, seafloor and water-column observatories with the basic scientific objective of (near)-real-time, long-term monitoring of environmental processes across the geosphere, biosphere, and hydrosphere. It is geographically distributed in key sites of European waters, from the Arctic, through the Atlantic and Mediterranean, to the Black Sea. EMSO will be the sub-sea segment of the COPERNICUS (former GMES-Global Monitoring for Environment and Security) initiative and will significantly enhance the observational capabilities of European Member States. EMSO is the European counterpart of many similar worldwide infrastructures, such as ONC in Canada, OOI in US, DONET in Japan or IMOS in Australia. EMSO ended its Preparatory Phase, EU Framework 7 funded project in 2012, and now is in the Interim phase transitioning to the formation of the legal entity for managing the infrastructure: The EMSO European Research Infrastructure Consortium (hereinafter EMSO-ERIC). A phased implementation will characterize EMSO site extension, construction and operation. The overall duration of the first phase of EMSO implementation will be 5 years from the ERIC foundation, with a review point scheduled at year 3. From the technological point of view, the most striking characteristic of observatory design is its ability to address interdisciplinary objectives simultaneously across temporal and spatial scales. Data are collected from the surface ocean, through the water column, the benthos, and the sub-seafloor. Depending on the application, in situ infrastructures can either be attached to a cable, which provides power and enables data transfer, or operate as independent benthic and moored instruments. Data, in both cases, can be transmitted real-time through either fibre optic cables, or cable and acoustic networks that are connected to a satellite-linked buoys. Cabled infrastructures provide important benefits such as high power and bandwidth for realtime data transfer when a processing of huge amount of data (as for bioacoustics), or a real-time integration with land-based networks (as for the seismology), as well as rapid geo-hazard early warning systems. Test sites have shown technological challenges to be faced and the potential for answering important scientific questions.
Article
The EC has funded the European Seafloor Observatory Network (ESONET) Consortium with representatives from the UK, Norway, France, The Netherlands, and Sweden to develop a subsea component of the European Global Monitoring for Environment and Security system. ESONET has developed three underwater telescope array systems including Neutrino Experimental Submarine Telescope with Oceanographic Research (NESTOR), Astronomy with a Neutrino Telescope and Abyss Environmental Research (ANTARES), and Neutrino Mediterranean Observatory in the Mediterranean Sea. The seafloor observatories with multidisciplinary capabilities including geophysical and seismological have been developed under the guidance of EC Geophysical and Oceanographic Station for Abyssal Research (GEOSTAR) phase one and two projects, coordinated by the Instituto Nazionale di Geofisica e Vulcanologia (INGV). Technical advances have been made in EC projects, including Array of Sensors for Long Term Seabed Monitoring for Geo-hazards (ASSEM) and Ocean Research by Integrated Observation Networks (ORION)-GEO-STAR whose seafloor nodes are interlinked by acoustics.
Acoustic Doppler Profiler Technical Documentation
  • Sontek
  • Ysi
SonTek/YSI (September, 2000), Acoustic Doppler Profiler Technical Documentation, San Diego, CA, USA.