Hindawi Publishing Corporation International Journal of Oceanography Volume 2009, Article ID 232513, 19 pages doi:10.1155/2009/232513 Research Article Chlorophylls and Phycoerythrins as Markers of Environmental Forcings Including Cyclone Erica Effect (March 2003) on Phytoplankton in the Southwest Lagoon of New Caledonia and Oceanic Adjacent Area J. Neveux,1, 2 M. M. B. Tenorio,´ 1, 2, 3 S. Jacquet,4, 5 J.-P. Torreton,´ 4, 6 P. Douillet,4 S. Ouillon,4, 7 and C. Dupouy4 1 Laboratoire ARAGO, Universit´e Pierre et Marie Curie-Paris 6, Avenue Fontaul´e, BP44, 66650 Banyuls-sur-Mer, France 2 Laboratoire d’Oc´eanographie Biologique de Banyuls, CNRS, UMR7621, Avenue Fontaul´e, BP44, 66650 Banyuls-sur-Mer, France 3 Departamento de Biologia Marinha, Instituto de Biologia, Universidade Federal do Rio de Janeiro, Cidade Universitaria-CCS-Bloco´ A-sala A63, Ilha do Governador, Rio de Janeiro 21941-590 RJ, Brazil 4 Institut de Recherche pour le D´eveloppement, UR Cam´elia (UR 103), BP A5, 98848 Noum´ea Cedex, New Caledonia, France 5 Centre Technique Littoral, Lyonnaise des Eaux, Technopoleˆ Izarbel, 64210 Bidart, France 6 ECOLAG/UMR 5119, Universit´e Montpellier II, CC 093, 34095 Montpellier Cedex 05, France 7 Universit´e de Toulouse, IRD, LEGOS, 14 avenue Edouard Belin, 31400 Toulouse, France Correspondence should be addressed to J. Neveux, [email protected] Received 6 February 2009; Accepted 3 September 2009 Recommended by Robert Frouin Spatio-temporal variations of chlorophylls and phycoerythrins, inferred by spectrofluorometric methods, were studied from April 2002 to June 2003 in the southwest lagoon and oceanic waters of New Caledonia. Trade winds blew 75% of the time and appeared as the main factor influencing surface Tchla (sum of monovinyl- and divinyl-chlorophyll a) variations in the ocean, near the barrier reef. Lagoon and oceanic waters differed in the composition of picoplanktonic cyanobacteria with a relative dominance of Prochlorococcus and high-phycourobilin Synechococcus in the ocean, and a relative dominance of high-phycoerythrobilin Synechococcus in the lagoon. Main pigment variations in the lagoon were associated with cyclone Erica in March 2003 and showed a 5-6 fold Tchla increase around Noumea.´ The cyclone stimulated mainly diatom growth as indicated by the high chlorophyll (c1 + c2)/chlorophyll a ratio and by the lowest values for the other pigment ratios. The relative importance of divinyl-chlorophyll a concentration and fluorescence excitation spectra of phycoerythrins appeared as useful tools for characterizing lagoon-ocean exchanges. Copyright © 2009 J. Neveux et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. 1. Introduction genus Prochlorococcus. The discrimination between these two pigments provides essential information about community Phytoplankton pigments (chlorophylls, carotenoids, phy- structure in oligotrophic waters where Prochlorococcus often cobiliproteins) remain a major source of information on represents more than 50% of the Tchl a [1, 2]. biomass, community structure, dynamic, and physiological Previous research on pigments in New Caledonian waters state of phytoplankton. The old concept of chlorophyll concerned mainly the south west lagoon (SWL, Figure 1) a concentration as a proxy of phytoplankton biomass is and was limited to bulk chl a concentration distribution now represented by the sum of two chemical entities (Tchl and variations [3–10]. Early work reported increasing Tchl a): the monovinyl-chl a (chl a), associated to most of the a concentration from the ocean through the coastal lagoon photooxygenic organisms, and the divinyl chlorophyll a (dv- to the estuaries with maxima found after flooding and chl a) specifically associated to the cyanobacteria of the in urban effluent areas [3]. However, it did not provide 2 International Journal of Oceanography −22◦10S Dumbéa Bay D47 D46 D37 D39 D41 D27 ◦ Grande −22 15 S D19 B03 M03 D12 D08 Rade D01 B08 Boulari Bay B16 NoumeaN04 N12 N44 N20 Ste Marie B18 (km) Bay N30 052.5 N33 N43 N40 B24 B26 −22◦20S 166◦20E 166◦25E 166◦30E Dumbéa river M27 Uitoé pass MAA D41 M25 La Coulée river M37 M03 L3 Pirogues M06 ransect river M16 N44 ◦ M09 P04 18 S N43 B26 B24 ◦ Dumbéa t P12 −22 20 S O3 M12 M33 O2 L2 19◦ Dumbéa pass O1 A03 N ◦ ransect 20 ri t A11 Boula 21◦ New Caledonia ◦ A17 −22 30 S (km) 0105 ◦ Boulari pass 22 Coral sea Nouméa 166◦10E 166◦20E 166◦30E 166◦40E 23◦ 163◦ 164◦ 165◦ 166◦ 167◦ 168◦E Figure 1: Map of the sampling locations. Stations sampled (1) at five depths with a mean frequency of 10.3 days (N12 and M33: open squares), (2) monthly at the surface (dark circles), (3) monthly (open circles) at the surface and near the bottom (lagoon: L2, L3, MAA) or at six depths from 0 to 100 m (ocean: O1), (4) during the tide cycles (O1, O2, O3, L2, L3). any evidence of Tchl a temporal periodicity. More recent are the main environmental factors that can explain the investigations highlighted the occurrence of clear daily and Tchl a variations in the SWL. A coupled three-dimensional seasonal trends for Tchl a [9, 10]. The seasonal signal physical-biological model was developed to simulate the could also be extracted from a four-year long time series Tchl a distribution in the SWL from freshwater input, (1979–1983) by spectral analysis using wavelet methods [8]. trade winds intensity, and hydrodynamics [12]. This model Nevertheless, short-term fluctuations (1-2 weeks) related demonstrated that eutrophication is limited to coastal bays to local but usual meteorological event are in the same and oligotrophic conditions prevailed in most part of the range than annual variations [9]. Winds, precipitations lagoon. In the ocean, results were relatively scarce. A general [9], anthropogenic activities [10], and hydrodynamics [11] enrichment in chlorophyll of surface waters of the Coral Sea International Journal of Oceanography 3 Table 1: Sampling interval, period, and stations as well as physico-chemical (P-C. P.) and biological (B. P.) parameters measured during the different operations. Period Stations interval P-C. P. B. P. Apr 02-Apr 03 (S1) N12, M33 10 ± 3.6 days T., S., IF, Nut.2 Chl, PE, FC Apr 02-May 03 (S2) O1, L2, L3, MAA Monthly T., S., IF, Nut.3 Chl, PE, FC4 Sep 02-Apr 03 (S3) Other stations1 Monthly T., S., IF Chl5,PE5 13-14 June 036(S4) O1, O2, O3, L2, L3 Tide cycles T., S., IF, Nut.3 Chl, PE T. = Temperature; S. = Salinity; IF = in vivo chl a fluorescence; Chl = chlorophylls; PE = phycoerythrins; FC = cell counts by flow cytometry; Nut. = nutrients. 1 2 3 4 5 28–30 stations in the south west lagoon according to weather conditions; NO3+NO2,PO4,NH4,Si(OH)4; NO3+NO2,PO4; April 2003 only; sampling at the surface only; 6Diapalis 8 cruise. until 20◦S is observed during winter cooling and consecutive southwestern part, it is larger and separated from the ocean water column mixing [13]. Another increase of Tchl a near by a nearly continuous emerging barrier reef interrupted the barrier reef (Uitoe´ pass) seems related to nutrients and only by a few passages (Figure 1). At the southeast end, Tchl a ouput from the lagoon [14]. Nevertheless, during it is more open to the surrounding ocean and the main trade wind events, upwelling along the barrier reef could also input of oceanic waters to occur there, especially when enhance the phytoplanktonic production [15]. southeast trade winds are blowing [23]. Its mean depth is The bulk Tchl a concentration does not give information 17.5 m, but maximum depths of 60–70 m are observed in on the effect of environmental forcing on the structure the narrow canyons located in front of the passes. Climatic of phytoplankton communities. Other phytoplankton pig- conditions are characterized by periods of heavy rain in ments can help to determine this structure via more-or-less summer (200–600 mm per 24 h). River outflows and run- specific chemotaxonomic markers [16]. In the present work, off from the steep slopes bordering the lagoon carry mineral spectrofluorometric methods were implemented to analyze and organic particulate matter as well as dissolved nutrients the different chlorophylls [17, 18] and phycoerythrins [19, that can stimulate phytoplankton growth and productivity in 20] in samples collected during several investigations in the lagoon. Mining activities (nickel, chrome) also facilitate the SWL and in the adjacent oceanic area in 2002 and land erosion during runoff. The anthropogenic influence is 2003. Outside the information on community structure, the also important in the SWL and is related to waste water spectrofluorometric chlorophyll analysis reduces pitfalls in and industrial effluents originating from the capital of New the determination of Tchl a that are inherent to the classical Caledonia, Noumea´ [24], and its suburbs (nearly 160 000 fluorometric and spectrophotometric method [21]. inhabitants). The important question addressed in this study was ff how the community structure was a ected by environmental 2.2. Stations. Several operations were conducted at different forcing. For that, the objectives were (1) to examine temporal stations with various sampling interval using the R/V “Coris”. variability of phytoplankton biomass and community struc- They are summarized in Table 1. ture through pigment composition in relation to variations From 4 April 2002 to 9 April 2003, morning sampling of environmental physico-chemical factors at the weekly, (S1) was realized at two stations with a mean (±SD) interval monthly, and seasonal scales, and (2) to analyze the effect of 10.3 (±3.6) days (Figure 1,opensquares).Theobjective of meteorological events as strong SE trade winds (mean was to compare a station submitted to untreated sewage 20 knots), heavy rains, cyclone on the pigment abundance, input from Noumea´ (N12 in the Sainte Marie Bay; sampling and distribution in the SWL.