CaVortEx IV OCEANOGRAPHIC CRUISE OBSERVERSHIP › Article › PDF › October2005.pdf · In Photo 2...

CaVortEx IV

OCEANOGRAPHIC CRUISE

OBSERVERSHIP

by

Ava Maxam

Department of Life Sciences

University of the West Indies

Introduction

Mesoscale eddies are large, oceanic whirlpools that have been found to traverse the Caribbean from east

to west at a rate of about 4-5 per year. They tend to become stronger as they reach the western Caribbean,

maintaining diameters of hundreds of kilometers with effective depths of over 800 m. One such feature

was the center of investigations during the CaVortEx IV (Caribbean Vorticity Experiment) expedition

undertaken by scientists from the University of Puerto Rico during March 12-25, 2005. The objective was

to investigate eddy effects on biological processes, their contribution to large scale ocean circulation, and

their variability in response to global change.

The eddy known as the Haiti-Jamaica Anti-cyclone (HJA) is a large, mature, anticyclonic feature (see

Figure 1) believed to have originated from complex interactions amongst southern flow through the Mona

Passage, westward Caribbean flow and the Hispaniola coastal projection.

Figure 1: Satellite imagery of sea surface height in the central Caribbean for March 19, 2005. Red

portions depict the Haiti-Jamaica

anticyclonic eddy under investigation during the CaVortEx IV Cruise March 12-26, 2005.

(Processed satellite imagery provided by R. Lopez, UPR, and used with permission.)

Research was conducted on board the RV Pelican (see Photo 2) owned and operated by the Louisiana

University Marine Consortium (LUMCON). The Office of Naval Research (U. S. Navy) serves as the

sponsoring institution for the study of Caribbean eddies with additional support from the NASA-UPR

Tropical Center for Earth and Space Studies (TCESS) and the Department of Marine Sciences (DMS),

UPR (see Photo 1).

In the above photograph (Photo 1) it shows section of Magueyes Island showing facilities at the

Department of Marine Sciences, UPR, where graduate students have access to modern laboratories

equipped with state of the art equipment and Research Vessels for marine and oceanographic research.

In Photo 2 the R/V Pelican docked at Magueyes Island March 11, 2005. The 116

Vessel was designed and outfitted to conduct a variety of oceanographic research missions, including

scientific trawling, large box core sampling, shallow seismic surveys, current meter array and benthic

boundary array deployment and recovery, pla

systems, and underway sampling with towed water sampling systems. The Louisiana Universities Marine

Consortium operates the vessel.

CaVortEx IV Crew

Members on board consisted of twelve scientific crew

Marine Consortium (LUMCON) crew. The scientific team were all from the University of Puerto Rico

Photo1: Magueyes Island.

) it shows section of Magueyes Island showing facilities at the

nt of Marine Sciences, UPR, where graduate students have access to modern laboratories


Photo 2 The R/V Pelican

In Photo 2 the R/V Pelican docked at Magueyes Island March 11, 2005. The 116 – foot long



boundary array deployment and recovery, plankton sampling, hydrographic casts with CTD


Members on board consisted of twelve scientific crew, one observer and six Louisiana Universities


) it shows section of Magueyes Island showing facilities at the

nt of Marine Sciences, UPR, where graduate students have access to modern laboratories


foot long Research



nkton sampling, hydrographic casts with CTD-rosette


, one observer and six Louisiana Universities


and included Drs. José M. López (Principal Investigator), Jorge E. Corredor (Co

(Co - P. I.), Jorge E. Capella, and Fernando Gilbes; and graduate students Alvaro Cabrera, Miguel Canals,

Ramón López, Ana Lozada, Marla Mendez

was invited on board to represent the coastal state of Jamaic

research. As a PhD marine scientist studying physical and biological characteristics of water circulation

around reefs, Ava Maxam of the Life Sciences Dept., UWI, represented the government of Jamaica.

The ship’s crew was provided by LUMCON with Dave Pond as captain, supported by Craig LeBouef

(relief captain), Jim Dorrance (marine technician), Jack Pennington (engineer), José Montoya (marine

technician) and Steve Joltki (chef).

Scientific Methods and Instrumen

Several oceanographic and bio-optical instruments for the measurement of parameters that influence the

photosynthetic behaviour of phytoplankton were employed, including the rosette of instruments in Photo

3 assembled by the Geological and Environme

irradiance and radiance, spectral transmittance and light absorption, variable fluorescence, attenuation and

backscattering.

Photo 3 Bio-optical rosette assembled by scientists from UPR.

The FASTtracka

Fluorometer was another bio

measurements of photosynthetic characteristics of phytoplankton. Also deployed was the Profiling

Reflectance Radiometer (PRR), an optical instrument designed to make profiles of downwelling

irradiance and upwelling radiance through the upper 200 m of t

and included Drs. José M. López (Principal Investigator), Jorge E. Corredor (Co - P. I.), Julio M. Morell

. I.), Jorge E. Capella, and Fernando Gilbes; and graduate students Alvaro Cabrera, Miguel Canals,

Ramón López, Ana Lozada, Marla Mendez-Silvagnoli, Milton Muñoz, and Wilson Rovira. One observer

was invited on board to represent the coastal state of Jamaica and to participate in the oceanographic



s crew was provided by LUMCON with Dave Pond as captain, supported by Craig LeBouef


Scientific Methods and Instrumentation

optical instruments for the measurement of parameters that influence the


3 assembled by the Geological and Environmental Remote Sensing Laboratory at UPR to measure


optical rosette assembled by scientists from UPR.

Fluorometer was another bio-optical instrument that offered rapid, real-time,



irradiance and upwelling radiance through the upper 200 m of the water column, and its sister instrument

P. I.), Julio M. Morell

. I.), Jorge E. Capella, and Fernando Gilbes; and graduate students Alvaro Cabrera, Miguel Canals,

Silvagnoli, Milton Muñoz, and Wilson Rovira. One observer

a and to participate in the oceanographic



s crew was provided by LUMCON with Dave Pond as captain, supported by Craig LeBouef


optical instruments for the measurement of parameters that influence the


ntal Remote Sensing Laboratory at UPR to measure


time, in situ



he water column, and its sister instrument

the PRR 610 for simultaneous reference downwelling irradiance measurements at the sea surface. The

Chelsea N×-Shuttle towed vehicle system measured fluorometry and CTD parameters while undulating

underwater behind a moving vessel at speeds of 5

and 5).

Photo 4 Pelican Marine technicians deploy the N

Photo 5 Deck unit of the N×-Shuttle

underwater.

BIOGEOCHEMICAL


Shuttle towed vehicle system measured fluorometry and CTD parameters while undulating

a moving vessel at speeds of 5-15 knots, to operational depths of 150m (see Photos. 4

Marine technicians deploy the N×-Shuttle towed vehicle system.

Shuttle towed vehicle system displaying relayed data as the vehicle ‘flew’


Shuttle towed vehicle system measured fluorometry and CTD parameters while undulating

15 knots, to operational depths of 150m (see Photos. 4

Shuttle towed vehicle system.

towed vehicle system displaying relayed data as the vehicle ‘flew’

Water samples were collected using a rosette sampling system (see Photos 6 and 7). Samples were

subjected to a variety of biochemical tests. For dissolved oxyge

carried out on immediately fixed samples. Productivity analysis via radioactive

measurements was carried out in the radioisotope lab. Samples for chlorophyll

analyses were collected directly from Niskin sampling bottles into brown polyethylene sampling bottles.

Nutrients analyses were performed for dissolved organic and inorganic compounds content after filtration

and cold storage of samples.

Photo 6 Pelican Marine technicians deploy the smaller rosette sampler from the J


subjected to a variety of biochemical tests. For dissolved oxygen content an iodometric titration was

carried out on immediately fixed samples. Productivity analysis via radioactive 14

C assimilation

measurements was carried out in the radioisotope lab. Samples for chlorophyll a and primary productivity

llected directly from Niskin sampling bottles into brown polyethylene sampling bottles.


Marine technicians deploy the smaller rosette sampler from the J-frame.

Photo 7 The Large A-Frame


n content an iodometric titration was

C assimilation

and primary productivity

llected directly from Niskin sampling bottles into brown polyethylene sampling bottles.


frame.

In photograph 7, we see the large A

sampler (on the left) deployed. The van on the right of the photo houses the radioisotope lab.

PHYSICAL

A self-contained broadband 150 kHz RDI ADCP was mounted on a standard R

to provide top-to-bottom velocity profile with each CTD cast, a method known as LADCP profiling. Raw

velocity data were processed to utilize CTD and navigation information. The Sippican Expendable

Bathythermograph (XBT) shown in

of the ocean to depths of up to 1000 meters. XBT’s were deployed over 24

moved between stations.

Photo 8 Larger rosette frame being deployed with the yellow LADCP attached bottom right of frame.

he large A-frame is shown in the background from which the larger rosette


contained broadband 150 kHz RDI ADCP was mounted on a standard Rosette frame (see Photo. 8)

bottom velocity profile with each CTD cast, a method known as LADCP profiling. Raw


Bathythermograph (XBT) shown in Photo. 9 was used to obtain information on the temperature structure

of the ocean to depths of up to 1000 meters. XBT’s were deployed over 24-hour schedules as the ship

Larger rosette frame being deployed with the yellow LADCP attached bottom right of frame.

frame is shown in the background from which the larger rosette


osette frame (see Photo. 8)

bottom velocity profile with each CTD cast, a method known as LADCP profiling. Raw


was used to obtain information on the temperature structure

hour schedules as the ship

Larger rosette frame being deployed with the yellow LADCP attached bottom right of frame.

Photo 9 An XBT is being deployed from the

Stations and Schedule

The CaVortEx IV cruise track comprised of ten sampling stations

Island to Port Antonio and only three on the return leg because of bad weather (see Figure 2). After

leaving Puerto Rican waters bearing west, the cruise first chartered waters of the Dominican Republic,

then Haiti, into Jamaican territory, south towards Columbia, and then north again into Jamaican waters to

dock at Port Antonio for a two-day stopover.

An XBT is being deployed from the Pelican.

The CaVortEx IV cruise track comprised of ten sampling stations – seven on the first leg from Magueyes



can territory, south towards Columbia, and then north again into Jamaican waters to

day stopover.

n the first leg from Magueyes



can territory, south towards Columbia, and then north again into Jamaican waters to

Figure 2 Map of CaVortEx IV cruise track and sampling stations, March 12

The first station was arrived at after three days of traveling to the general eddy vicinity and then searching

for the center of the circulation. Projection models of sea surface height topography (ssht) were used as a

guide to locate the center. Sampling then

from the centre of the eddy to its periphery. On the return leg a transect from West

but rough seas prevented its completion.

Sampling at each station involved deployment

Water samples were collected or filtered from the Niskins and data downloaded from the instruments.

While in transit between stations the N

released every hour on the hour until arrival at the next stop.

Map of CaVortEx IV cruise track and sampling stations, March 12-25, 2005.

first station was arrived at after three days of traveling to the general eddy vicinity and then searching


guide to locate the center. Sampling then occurred along a South-North transect (Stations 1

from the centre of the eddy to its periphery. On the return leg a transect from West-East was attempted

but rough seas prevented its completion.

Sampling at each station involved deployment of the Niskin and Optics rosette systems to about 300m.


While in transit between stations the N× – Shuttle System was continuously deployed. Also, XBT’s we

released every hour on the hour until arrival at the next stop.

25, 2005.

first station was arrived at after three days of traveling to the general eddy vicinity and then searching


North transect (Stations 1-6), extending

East was attempted

of the Niskin and Optics rosette systems to about 300m.


Shuttle System was continuously deployed. Also, XBT’s were

Preliminary Results

In summary, initial results showed that waters were of exceptional optical purity, that is, there was very

little suspended or dissolved material content. The dat

will be made available at a later date to the Department of Life Sciences, UWI, in an official CaVortEx

IV research publication to be completed by the scientists from the UPR.

BIOGEOCHEMICAL DATA

The following graphs in Figure 3 depict salinity, temperature and chlorophyll

of the cruise.

Figure 3 Depth profiles of Salinity, Temperature and Chlorophyll

n summary, initial results showed that waters were of exceptional optical purity, that is, there was very

little suspended or dissolved material content. The data is presented here in preliminary form and the rest


IV research publication to be completed by the scientists from the UPR.

following graphs in Figure 3 depict salinity, temperature and chlorophyll a along the S to N transect

Depth profiles of Salinity, Temperature and Chlorophyll

n summary, initial results showed that waters were of exceptional optical purity, that is, there was very

a is presented here in preliminary form and the rest


along the S to N transect

.

In Figure 3, the Depth profiles of Salinity, Temperature and Chlorophyll a along the S-N transect of the

CaVortEx IV cruise. The HJA eddy core is located closest to the south end of the transect. The warmer,

low salinity central core of the eddy was exceptionally deep (see Figure 3 (a) and (b)), depressing

nutrient-rich bottom layers and resulting in low productivity from phytoplankton as evidenced by lowered

chlorophyll a eddy core values in Figure 3 (c).

PHYSICAL DATA

At stations 1 and 2 the eddy structure was clearly defined, with circulation occurring clockwise as

expected with an anti-cyclonic eddy (see Figure 4). LADCP results in Figure 4 showed that current

speeds were strongest just around the centre of the eddy (at Station 1) and at surface. The most active

parts of the eddy seemed to be confined to the top 400m.

CaVortEx IV preliminary LADCP data provided by M. Canals, UPR, and used with permission.

CaVortEx IV preliminary LADCP data provided by M. Canals, UPR, and used with permission.

CaVortEx IV LADCP Vector Field

Figure 4 Graphs of CaVortEx IV LADCP vector fields

Graphs of CaVortEx IV LADCP vector fields

In Figure 4, Graphs of CaVortEx IV LADCP vector fields showing current vectors (m/s) of the

anticyclonic eddy at depth. The uppermost mixed layer depicts the strongest currents near to the center of

the HJA. Circulation is in a clockwise direction.

OPTICAL DATA

Optical data showed that waters of the HJA contained very little suspended or dissolved m

The waters showed very high optical purity.

Observership Experience

During the cruise Ms. Maxam carried out XBT deployments and logs, collected water samples from the

Niskin rosettes and assisted the biogeochemical team in preparing

samples for scintillation analysis in the radioactive laboratory. Her role during the CaVortEx IV mission

allowed her to contribute to the data collection and get exposure to instrumentation and methodology not

available in Jamaica. A small team of graduate students from the University of the West Indies (including

Ms. Maxam) has sought to carry out graduate work in physical oceanography but lack of instrumentation

and local scientific instruction in the field has limited the

participating in this oceanographic cruise is therefore bifold in that the

her personal studies and opens the way for adding a new oceanographic field to the Jamaican curriculum.

The experience to be gained from oceanographic cruises such as the CaVortEx IV is valuable, even more

so if comprehensive pre-cruise collaboration is achieved. For future observer

suggested that their role be more applied and usefu

training beforehand in one unfamiliar component of oceanography with the organizing academic

institution. This can be organized as a student exchange between the University of the West Indies and the

organizing institution.


cyclonic eddy at depth. The uppermost mixed layer depicts the strongest currents near to the center of

the HJA. Circulation is in a clockwise direction.

Optical data showed that waters of the HJA contained very little suspended or dissolved m

The waters showed very high optical purity.


Niskin rosettes and assisted the biogeochemical team in preparing 14

C-spiked, incubated phytoplankton



amaica. A small team of graduate students from the University of the West Indies (including


and local scientific instruction in the field has limited the scope of analysis. The significance of

participating in this oceanographic cruise is therefore bifold in that the knowledge gained contributes to


xperience to be gained from oceanographic cruises such as the CaVortEx IV is valuable, even more

cruise collaboration is achieved. For future observer-scientists from Jamaica it is

suggested that their role be more applied and useful to both parties by at least a month of academic




cyclonic eddy at depth. The uppermost mixed layer depicts the strongest currents near to the center of

Optical data showed that waters of the HJA contained very little suspended or dissolved material content.


piked, incubated phytoplankton



amaica. A small team of graduate students from the University of the West Indies (including


scope of analysis. The significance of

knowledge gained contributes to


xperience to be gained from oceanographic cruises such as the CaVortEx IV is valuable, even more

scientists from Jamaica it is

l to both parties by at least a month of academic



Photo 10 Ms. Maxam (right), scientific observer, in the physical oceanography lab to which she was

assigned. To her right are graduate students Messrs. Canals and Rovira, also assigned to the same area.

Application of Covortex Science to Jamaica

The annual path of the HJA places the eddy in the vicinity of the Pedro Cays, one of Jamaica’s most

productive offshore fishing banks. NLOM Operational Models show that eddies (cyclonic or

anticyclonic) are especially strengthened in this area. Eddies are also responsible for mass

ichthyoplanktonic transport and basin ventilation across the Caribbean. The science utilized by the

CaVortEx expeditions can be applied to our offshore fisheries to document the seasonal effects of these

eddy systems on primary productivity values, current circulation and bio-optical properties of the waters.

Cyclonic eddies are especially important in upwelling nutrient rich bottom waters and increasing

productivity. Anti-cyclonic eddies give the opposite effect of depressing nutrient rich layers and

decreasing productivity.

The implication of the Windward Passage in its contribution to the propagation of these eddies is also

important. This is a busy shipping channel located off the east coast of Jamaica. In the event of

operational discharge, oil spills or other maritime disasters, knowledge of the circulation of the area is

crucial as this can directly affect water quality on the east and southeast coasts.

The remote sensing techniques combined with bio-optical measurements utilized for the CaVortEx

missions are not only useful for wide scale productivity measurements but also for a synoptic overview of

water quality and pollution. This can be very useful in mariculture management, change detection in

habitats (especially after natural disasters), erosion and suspended sediment drift observations,

eutrophication and toxic algal bloom detection.

An obvious advantage is the educational contribution of oceanography components that are not developed

for study in Jamaica. There is much scope for growth of oceanography and pre- and post-cruise

collaboration can allow for didactic exposure of Jamaican students to these fields.

Movies of the 1/16° Global NLOM link, March 2005:

http://www7320.nrlssc.navy.mil/global_nlom/globalnlom/ias.html

Astor, Y., F. Muller-Karger, and M. Scranton (2003), Seasonal and interannual variation in the

hydrography of the Cariaco Basin: Implications for Basin ventilation, Cont. Shelf Res., 23, 125-144.

Blough, N.V., O.C. Zafiriou, and J. Bonilla (1993), Optical absorption spectra of waters from the Orinoco

River outflow: Terrestrial input of colored organic matter to the Caribbean, J. Geophys. Res., 98, 2271-

2278.

For additional information contact:

Ava Maxam,

Department of Life Sciences,

University of the West Indies, Mona,

Kgn 7, Jamaica.

Tel: (876) 927 1202/2753

Fax: (876) 927 1075

Mob: (876) 396 1777

Email: [email protected]

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