Marine Environmental Assessment Study

Luis D'Croz, Juan B. Del Rosario, and Plinio Góndola
The Marine Environmental Assessment Study (MAREAS) is a branch project of the STRI's Marine Environmental Science Program (MP) Its mission is to investigate the pattern of water-quality and plankton production near coral reef habitats in both sides of the Isthmus of Panama. This project parallels several of the objectives of the Long-Term Environmental Research Network of the National Science Foundation, specifically the study of:
  • The pattern and control of the primary production of coastal marine plankton.
  • The spatial and temporal distribution of coastal marine plankton.
  • Patterns of dissolved inorganic nutrients.
  • Pattern and frequency of major natural disturbances affecting marine coastal organic production, such as the upwelling, fresh-water runoff, ENSO related changes, and the incursion of oceanic waters in the continental shelf.

Study sites.

Marine coastal areas in Panama represent at least four contrasting environmental settings:

in the eastern Pacific Ocean: (a) the Gulf of Panama, affected by seasonal upwelling vs. (b) the Gulf of Chiriqui, no-upwelling environment.
in the Caribbean Sea: (a) the San Blas Archipelago, with narrow continental shelf, high ocean influence, and small input from fresh-water runoff vs. (b) the Bocas del Toro Archipelago, with larger continental shelf, and presumably high influence from continental run-off.
Bay of Panama, Pacific Panama. MAREAS started in 1985 with a single sampling site in the Bay of Panama and collections have been weekly carried ever since. The Bay of Panama is a coastal environment subjected to seasonal upwelling, and also to ENSO related sea- warming. Coral reef development is marginal. The sampling site is located in the head of the Gulf of Panama, NE of Taboga Is., where studies on the hydrology and oceanography were conducted previously (Smayda 1966; D'Croz et al. 1991, D'Croz and Robertson 1997). Similarity in results with studies by Smayda (1966) and Forsbergh (1969) suggest the study site is fairly representative of this section of the Bay of Panamá.
San Blas Archipelago, Caribbean Panama, weekly collections were carried at four sites near San Blas Point, an area with extensive coral reef development, from October 1993-June 1998. The logistic for sampling was supported by the former STRI field station located in the area. This study ended in 1998 due to the termination of the contract between STRI and the Kuna Congress.
Bocas del Toro, Caribbean Panama. After the closure of the STRI San Blas field station, bi-weekly collections of water and plankton were started in January 1999, at five sites representatives of mangrove, seagrass, and coral reef environments in the Archipelago of Bocas del Toro. The archipelago is next to a large coastal lagoon. STRI is currently building up a research facility at Isla Colon. Field work was concluded in December 2001.
Field and laboratory methods (click on the links to download data) .
  • Water samples are collected at surface, mid-water, and near-bottom levels, using 3 L Niskin samplers. Three replicates are collected at each sampling site.
  • Temperature. It is measured during the collection of water samples using protected reversible thermometers installed in the Niskin samplers (precision 0.01 C), or immersing the probe of an electronic thermistors (precision 0.1 C) in the freshly collected sample.
  • Salinity. Salinity is measured in the laboratory using the salinometer Lab-Comb model SCT (precision of 0.01 ppt), or the YSI temperature-salinity-oxygen meter model 85 (precision 0.1 ppt).
  • Water transparency. Secchi disk readings are used to estimate water visibility to the nearest 0.1 m.
  • Chlorophyll. The concentration of chlorophyll a was originally measured by spectrophotometry until June 1999, and since then by fluorometry, following the methods of Parsons et al. (1984) and Jeffrey et al. (1997). For this, from 0.5 L to 2.0 L of the collected water is passed through fiber-glass filters (0.45 µm). The volume of filtration for the analysis depend on the concentration of plankton in the water sample. Filters holding the phytoplankton are ground with a Teflon pestle and pigments extracted in a solution of 90% acetone in distilled water.
  • Zooplankton. Sampled with 0.5 m diameter standard nets, 300 µm mesh, fitted with digital General Oceanic flow-meter model 2030 to measure the volume of water. At each site, 2-4 replicated oblique tows are carried for 30 minutes, from the depth of 20 m to the surface. The net is towed at approximately 1 knot. The collected plankton is preserved in 5% formalin solution diluted in seawater. Each zooplankton sample is entirely sorted for fish larvae and then subdivided in a Folson splitter as far as 1/64 until the last two sub-samples have approximately 2,000 to 3,000 individual plankters. Organisms in both sub-samples are counted and sorted into major taxa using stereo-microscopes and their density per cubic meter is calculated.
  • Dissolved inorganic nutrients. A volume of 250 mL of filtrate from the chlorophyll test is set apart and frozen (< 5 C) for further analysis of dissolved inorganic nutrients. Water samples were analyzed for nitrite-nitrate, phosphate, and silicate following Parsons et al. (1984), and using the Milton Roy Spectronic 1201 spectrophotometer, until June 2000, and afterward using the automated analyser OI Analytical ALPKEM model Flow-Solution IV. The quality control for the automated analysis includes: duplicated analysis; independent calibration verification; continuing calibration verification; and spiked samples.
Data collected.

The data were originally archived in Dbase format files, but can be easily transformed into comma delimited ASCII files for any other purpose. Most of the collected information have been digitalized using FoxPro which permit the arrangement of data in any desired format. Columns in a table are referred to as "fields", and rows are referred to as "records" in accordance to the convention used by Dbase.

According to the nature of the collected data the files are created so we have station data, field level data, dissolved inorganic nutrients, chlorophyll a, and zooplankton files. Most of the data was collected on a regular schedule. Each time a collection of data was made, it was assigned a collection identification number (CID), unique to that particular data set. These numbers are sequential, but may not necessarily start at 1, and some numbers may be skipped for various reasons. Each collection site is assigned with an unique 4 letter acronym.

The arrangement of the data in the tables is designed to permit cross tabulations which can be used to arrange it in any manner desired. We have avoided the use of different columns for the same kind of data, such as a separate column for each chemical o biological measured parameter (water) or taxa (plankton) where each column contains the concentration or count of the number of species. Rather, there is one column for the parameter or species name, one column for concentration (nutrients) or count plankton, one column for the CID (or date), one column for the site and column for the depth level. If it is required to make a table with the CID (or date) across the top and species on separate lines for time series analysis, or species across the top and the date on separate lines for making a graph, this can be accomplished by doing a cross-tabulation on the appropriate fields. All species abbreviations and site names start with letters, and have only letters, and are 8 or less characters long so that they will make legal Dbase field names. Missing data is indicated by a -1 for a numeric field or a blank for a character field, unless otherwise indicated.
CTD Casts

CTD casts are carried out with the Idronaut Ocean Seven 316 to provide vertical profiles for temperature, salinity, oxygen, and fluorescence down to 600 m of depth. The conductivity and temperature sensors are calibrated by the manufacturer at the beginning of each calendar year. The fluorometer and the oxygen electrodes are calibrated with discrete water measurements. Water samples are collected with Niskin bottles. Chlorophyll a is analyzed by fluorometry and the dissolved oxygen using the Winkler titration. Included are data for salinity, temperature, dissolved oxygen, chlorophyll from selected CTD stations in the Pacific coast of Panama (see maps).
The Gulf of Panama CTD station is located at 07°44' N and 79°18' W (data included).whereas the Gulf of Chiriqui CTD station is located at 07°20' N and 79°82' W (data included). The data is archived in MS Excel files. CTD profiles for the Gulf of Panama and for the Gulf are also available.In additon CTD casts in shallow waters were carried in the Gulf of Panama (08°08' N and 79°18' W) during February 2000 (data included), November 2000 (data included), December 2000 (data included), and November 2001 (data included).
Time-series Time-series for plankton and water-quality variables are available for all locations where MAREAS has carried out monitoring, and as an example are the following graphs showing the monthly means of sea-surface temperature, and the concentration of chlorophyll, phosphate P-PO4, and nitrate N-NO3. Bars denote the SE.

 

Publications

D'Croz, L, Del Rosario JB & Gómez JA. 1991. Upwelling and phytoplankton in the Bay of Panama. Rev. Biol. Trop., 39(2): 237-245.

D'Croz, L & Robertson DR. 1997. Coastal oceanographic conditions affecting coral reefs on both sides of the Isthmus of Panama. Proc. 8th Int. Coral Reef Symp. 2: 2053-2058.

D’ Croz, L., D. R. Robertson & J. A. Martínez. 1999. Cross-shelf distribution of nutrients, plankton, and fish larvae in the San Blas Archipelago, Caribbean Panamá. Rev. Biol. Trop., 47(1-2): 203-215.

D'Croz, L, Kwiecinski, B, Mate, JL, Gómez JA & Del Rosario JB. 2003. El Afloramiento costero y el fenómeno de El Niño: Implicaciones sobre los recursos biológicos del Pacífico de Panamá. Tecnociencia, 5(2):35:49.

Forsbergh, ED. 1969. On the climatology, oceanography and fisheries of the Panama Bight. Bull Inter-Amer Trop Tuna Comm 14:49-259.

Jeffrey, SW, Matoura RFC & Wright SW. 1997. Phytoplankton pigments in oceanography. Monographs on oceanographic methodology. UNESCO Publishing. 661 pp.

Parsons, TR, Maita Y & Lalli CM. 1984. A manual of chemical and biological methods for seawater analysis. Pergamon Press, New York. 173 pp.

Smayda, T.J. 1966. A quantitative analysis of the Gulf of Panama. III. General ecological condition and phytoplankton dynamics at 8 degrees, 45 minutes N, 79 degrees 23 minutes W. From November 1954 to May 1957. Inter-Amer. Trop. Tuna Comm., Bull., 11 (5): 353-612 p.

Williams, R., Piontkovski, S., Mishonov, A., Lyubartsev, V., D'Croz, L. and Osore, M. 2001. Plankton biodiversity and biovariability in the Indian and Atlantic Oceans. Compact Disk. Darwin Initiative for the survival of species. Project 162/8/251.

Thesis associated to the Water Quality and Plankton project.

Contreras, Zuriani & Voltas, Lilian. 1987. Oceanografía de la Bahía de Panamá durante la temporada de afloramiento 1984-1985. (Oceanography of the Bay of Panama during the 1984-1985 upwelling event). School of Biology, University of Panama

Guerra, Elida y Vega, Melvis. 1993. Estudio de la población de copépodos calanoides relacionado al afloramiento costero y disponiblidad de fitoplancton en la Bahía de Panamá. (Abundance of calanoid copepods in the Bay of Panama and its relation to coastal upwelling and phytoplankton). School of Biology, University of Panama

Muñoz, Leopoldo. 1993. Biomasa del zooplancton de la Bahía de Panamá. (Biomass of zooplankton in the Bay of Panama). School of Biology, University of Panama

Higuera, Martha. 1996. Distribución del ictioplancton en el Golfo de San Blas durante la estación seca de 1995. (Spatial distribution of the ichthyoplankton in the Gulf of San Blas during the dry season of 1995). School of Biology, University of Panama

Fisher, Vitor y Peralta, Carlos. 1996. Diagnóstico poblacional de los copépodos calanoides en un área coralina del Golfo de San Blas. (Calanoid copepods from coral reef habitats in the San Blas Archipelago). School of Biology, University of Panama

Henry, Icilda y Hernández, Ileana. 1996. Larvas de peces de los arrecifes coralinos de la Comarca de San Blas. (Fish-larvae in coral reef habitats in the San Blas Archipelago). School of Biology, University of Panama

Collazos, Heidi. 1998. Procesos determinante de la renovación de micronutrientes inorgánicos disueltos en el agua de mar en ambas costas del Istmo de Panamá. (Temporal pattern of dissolved inorganic nutrients in coastal areas on both sides of the Isthmus of Panama). School of Biology, University of Panama

Domingo, Alana y Rodríguez, Yehudi. 2001. Distribución espacial y temporal de larvas ictioplanctónicas en el Archipiélago de Bocas del Toro. (Temporal and spatial distribution of ichthyoplankton in the Bocas del Toro Archipelago). School of Biology, University of Panama

Salazar, Maricela. 2001. Invertebrados planctónicos colectados con trampas de luz en arrecifes de coral en el Archipiélago de San Blas. (Planktonic invertebrates collected with light-traps in coral reefs in the San Blas Archipelago). School of Biology, University of Panama

Macias, Dayanara. 2002. Estructura trófica del plancton en el Pacífico de Panamá. (Plankton trophic structure in Pacific Panama). School of Biology, University of Panama