a quantitative analysis of the annual phytoplankton cycle of the magdalena lagoon complex (mexico)

Journal of Plankton Research Vol.7 no.4 pp.427-441, 1985

A quantitative analysis of the annual phytoplankton cycle ofthe Magdalena lagoon complex (Mexico)

Henk Nienhuis and Rafael Guerrero Caballero

Centro Jnterdisciplinario de Ciencias Marinas (Instituto PolitecnicoNacional), El Conchalito, P.O. Box 574, La Paz, Baja California Sur,Mexico

Abstract. An annual cycle of the micro- and nanophytoplankton cell densities of whole water samples incombination with the species composition, distribution and diversity of the microphytoplankton fraction inthe Magdalena lagoon system, Mexico, has been studied on a bi-monthly basis. Two major patterns weredetected: from November to May, high microphytoplankton densities (0 .5-1 .5 10* cells I"1) prevailthroughout a large part of the investigated area; from late spring to late autumn cell densities are much lower(5—250 103 cells I"1). During each period a number of microplankton assemblages occur, each with itscharacteristic diversity and stability. The distribution and density of the microphytoplanlaon is clearly relatedto the presence of nutrient-nch water pockets and the prevailing winds for part of the year, as documentedin earlier hydrological studies. The nanophytoplankton played a minor role during most of the year: thisfraction dominated quantitatively in only a few cases. Based on these data, the Magdalena lagoon complexcan be considered a very productive area. This is further substantiated by the presence of large quantitiesof several sardine and mackerel species, feeding almost exclusively on microphytoplankton. This revealsthe existence of an important short chain pathway in the food web of this coastal lagoon system

Introduction

Phytoplankton studies conducted in neritic waters in or near the Magdalena lagoon systemhave only dealt with short-term investigations (Acosta and Lara, 1977; Allen, 1934,1938; Cupp and Allen, 1938). Longhurst etal. (1967) recorded a few scattered biomassdata, indicating the existence of highly variable biomasses.

Taxonomic microphytoplankton studies (Allen, 1924, 1934, 1938; Cupp, 1930, 1934;Cupp and Allen, 1938; Gilbert and Allen, 1943; Gilmartin and Revelante, 1978;Nienhuis, 1981, 1982; Round, 1967; Smayda, 1975) in neritic waters along the northwestern coast of Mexico and in the Gulf of California revealed communities, mainlydominated by diatoms belonging to the genera Chaetoceros and Rhizosolenia. Gilmartinand Revelante (1978) and Nienhuis (1981) showed a strong admixture of species belong-ing to the genera Biddulphia, Coscinodiscus, Guinardia and Hemiaulus in the coastallagoons of Baja California on the Gulf of California side.

Successional patterns in phytoplanktonic cell densities, species composition, diversityand dynamics of different phytoplankton fractions are not well known for this part ofthe world. Smayda (1963, 1966) reported a very stable succession and cell density patternof the microphytoplankton for the Gulf of Panama during a triannual study, whileNienhuis (1981) recorded a series of unstable assemblages in a shallow lagoon in theGulf of California.

Recent studies by Gilmartin and Revelante (1978) and Zeitzchel (1970) in coastalwaters and lagoons of the Gulf of California, by Malone (1971a, 1971b) at neritic andoffshore localities of the Eastern tropical Pacific and by Durbin etal. (1975), McCarthyetal. (1974), Yentsch (1959) and Wattling etal. (1979) in estuarine environments along

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H.Nienhuis and R.Guerrero

the east coast of the USA have clearly documented the importance of the small sizefraction of the phytoplanlcton (referred to as nanoplankton) in the total biomass andproductivity.

The present paper reports the results of a 1-year phytoplankton study, includingnanoplankton and microplankton densities and the species composition and diversityof the microplankton fraction. Based on this information, the structure, succession andstability of the microphytoplankton assemblages are examined, and the pathway ofphytoplankton in the food web of the Magdalena lagoon system is discussed.

Study area

The Magdalena lagoon system (Figure 1) is located between 24°15'N and 25°20'Nand l l lo30'Wand 112° 15'W and covers - 1500 km2. It consists of three clearly dividedareas: (i) a chain of relatively narrow (0.2—2 km), shallow (mean depth 3.5 m) channelson the northern and southern side which run parallel to the coast and are partly borderedby a dense mangrove vegetation of Avicennia germinans and Rhizophora mangle; (ii)Magdalena Bay; and (iii) Almejas Bay. Magdalena and Almejas Bays form the centralpart of the lagoon system. The open sea connections of the northern and southernchannels and of Almejas Bay are narrow and shallow (0.2—2 km; maximal depth5—7 m), while the entrance to Magdalena Bay is wide and deep (4 km; maximal depth40 m). The connection between Magdalena Bay and Almejas Bay is 2.5 km wide(maximal depth 30 m). According to the classification system for the Mexican lagoons(Lankford, 1976) the channels are shallow barrier lagoons while Magdalena Bay andAlmejas Bay are tectonic structural lagoons.

Alvarez etal. (1975) characterized the Magdalena lagoon complex as anti-estuarine(Figures 2 and 3) because of the low precipitation (annual average 14 mm), the absenceof fresh water input and the high evaporation rate. Highest salinities (37.3 — 39.2%o)occurred in the channels; minima were recorded at the entrances (34.0 — 34.5%x>).Temperatures followed the same pattern with maxima during late summer(23.0-28.0°C) and lowest values during spring (16.0-23.6°C). Inorganic phosphateand nitrate nitrite concentrations were lowest in the channels, 0.5 —1.0 /tM and0.0 —0.5/xM, respectively, while values in the central part fluctuated between0.5 — 3.0 fiM and 0.5 — 15.0 /iM. In the western part of Magdalena Bay a characteristicwater mass was recorded throughout part of the year with low temperatures and highphosphate values caused by upwelling. In the shallow northern part of the same bayhigh nutrient concentrations were recorded. Based on capture data, Casas (1983) com-puted that 20 103 tons of sardines (Sardinops sagax caerulea, Opistonema sp., Etrumeusteres and Cetengraulis mysticetus) and mackerel (Scomber japonicus) are caught eachyear in Magdalena Bay and Almejas Bay, while shrimp (Pennaeus californiensis andP. stylirostris) are captured in the shallow channels.

Materials and Methods

Whole water surface samples (1 1) were taken during high tide at 20 stations (Figure1) every two months (September, November 1980 and January, March, May and July1981). They were preserved immediately with a buffered formaldehyde solution (4%)

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Annual pbytoplankton cycle of MagdaJena lagoon

10 KM

NORTHERN CHANNELS

SOUTHERNCHANNELS

Fig. 1. Map of the MagdaJena lagoon complex showing the main physiographic features with depths in mand locution of the stations.

for further laboratory processing.Cell densities were determined in a 25 ml counting cell using Utermohl's technique.

Before settling, a few drops of a Rose Bengal stain were added to facilitate the contrastbetween plankton and detritus. Phytoplankton organisms with a maximal diameter of5 25 fitn were considered nanoplanktonic, the other fraction was defined as micro-phytoplankton. Of the microphytoplankton, 250 cells were identified with a compoundmicroscope to determine the species composition of this fraction. In the case of chainforming cells, the length of the whole chain was used as a unit. Cupp (1943) and Licea(1974) were consulted for the diatom identifications; Sciller (1933, 1937) and Taylor(1976) were used for the dinoflagellates, while for the taxonomy of the blue green algaethe revised Drouet system, described by Humm and Wicks (1980), was applied.

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Fig. 2. Surface distribution of the temperature (A) in °C and the salinity (B) in 7 - during different seasons,modified after Alvarez el al. (1975).

The diversity (//') of the microphytoplankton was calculated with the Shannon andWeaver equation:

H' = -E [ro log2 {"_,i = l N N

where nt is the number of individuals of the ith species; N is the number of individualsin the sample; and S is the total number of species in the sample.

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Annual pfaytoplankton cycle of Magdalena lagoon

Fig. 3. Surface distribution of the phosphate (A) and nitrate-nitrite (B) concentrations in ^M during differentseasons, modified after Alvarez el al. (1975).

To compare the species composition of the different stations during one samplingperiod, the similarity was computed, using the following similarity index (SIMIN):

SIMIN = SIM(l,2) (2)

[(SD(1)] [(SD(2)]

where:

S SSIM(1,2)= E OhJChL) and SD(1)= L CV)2

i = l iV, N, i = l #,

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[•'•.'.••'.••'•| 50x10*-250x|0*

500 x I05- IOe

Fig. 4. Abundances of microphytoplankton (number of cells I"1) during different sampling periods.

where nu is the specified variable for the ith taxon in the sample; and N, is the numberof individuals in the first sample (Stander, 1970). The results were put in Treillisdiagrams in order to detect clusters of stations with high similarities.

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Annual phytoplankton cycle of Magdalena lagoon

250 x I0 3 - 500 x I 0 3

50 x 10 s- 250xl03

500 xlO3- 10

_ > 10°

Fig. 5. Abundances of nanophytoplankton (number of cells I"1) during different sampling periods.

Results and Discussion

In the microphytoplankton fraction, 154 species were recorded, of which 145 wereidentifed to species level. Roughly 25 species were primarily responsible for the general

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Table I. Composite successional pattern and average biomass (103 cells I"the different areas of the Magdalena Bay lagoons

') of the microphytoplankton of

Area

I

II

III

rv

V

VI

Species

Bacleriastrum delicatulumBiddulphia mobiliensisCeratium furcaC. fususC. triposChaetoceros cun-isetusC. decipiensC. gracilisC. affinisDitylum brighrwelliGuinardia flaccidaNitzscia closteriumRhizosolenia calcar a\isR. setigeraSkeletonema costarumThalassionema nirzschioides

Biddulphia mobiliensisChaetoceros curvisetusGuinardia flaccidaNosloc spumigcnaRhizosolenia calcar avisR. styliformis

Eucampia zoodiacusGuinardia flaccidaHcmiaulus sinensisRhizosolenia alataR. styliformis

Bacleriastrum delicatulumCeratium furcaChaetoceros constrictusC cumsetusC. decipiensCoscinodiscus eccentricusC. wailesiiDitylum brightwelliEucampia zoodiacusGuinardia flaccidaRhizosolenia alataThalassionema nitzschioides

Chaetoceros cunisetusEucampia zoodiacusGuinardia flaccidaRhizosolenia alataR. calcar a\is

Guinardia flaccidaNnzschia sp.Rhizosolenia alataR. calcar a\is

Sep.

1

12

10

5

1

1313

678

10

4

4

32331

141598

7

Nov

1

113

2

925

4

49

424

1198

62

7

27

47

2

124

12364

2

Jan

2120

121

2212

9126

1

3

1217

11

416

61

3827

7

53

88235

32

8

11

March

592

12341

157

1

12

11

5

2055

271

34

64

182

2

3

4

19524

5

42

5

May

2

141377065

3105

10611

88

39

1

215

95

3013

2

261

164

5831

49

114

June

36

8010071162

27

233

97

6

27329

3

410

27

202

816

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Annual pbytoplankton cycle of Magdalena lagoon

VII Guinardia flaccida 7 78 74 36

209 105

VIII Aainoptychus splendens 55

32 19

42 78 6

Guinardia flaccidaNitzschia sp.lHemiaulus membranaceusRhizosoltnia alata

Aainoptychus spltndtnsBiddulphia mobiliensisGuinardia flaccidaNitzschia sp.lMelosira sulcataRhizosoltnia alataR. caJcar misR. imbricataSchizothrix mexicana

13

3

7

711

6

1022

dynamics of the annual cycle. With the exception of two species of blue green algaeand three dinoflagellates, all were diatoms. Though no further efforts were made toidentify the nanoplankton fraction at species level, it was noted that the great majoritywere Chrysophyceae and Cryptophyceae; occasionally small naviculiod diatoms andGymnodinium-\ike dinoflagellates enriched this fraction.

The temporal and spatial distribution of both fractions (Figures 4 and 5) indicate thepresence of very well marked microphytoplankton densities; the nanoplankton distri-bution seems very irregular. The cumulative abundance emphasizes clearly the minorrole of the nanoplankton ( < 5 0 - 103 cells I"1) with the exception of November, whenhigh concentrations were recorded at a number of stations (250 — 500 103 cells I"1).

Comparison with nanoplankton data in the literature is severely hampered by the factthat a whole range of definitions and methodologies are used to characterize this frac-tion, as summarized by Malone (1980). The advantage of the size criterion used inthis study, which roughly equals the one proposed by Dussart (1965), is that each frac-tion corresponds to different taxa. Diatoms and dinoflagellates mainly belong to themicroplankton, while the bulk of the nanoplankton consists of Chrysophyceae andCryptophyceae. During a 1-year cycle Wattling et al. (1979) recorded in DelawareBay, USA, three short outbursts of Chrysophyceae and Cryptophyceae of a few millioncells I"1. This indicates that lagoon and bay systems might contain high concentrationsof these taxa during a short period, but do not have suitable conditions for the develop-ment of dense, stable communities. The high nanoplankton densities recorded by Durbinet al. (1975) and McCarthy et al. (1974) are mainly caused by small, chain formingdiatoms, similar to those found at the entrances of the northern channels and MagdalenaBay during part of the year (Table I); however, they are never recorded inside thechannels and the inner parts of Magdalena Bay and Almejas Bay.

Two very stable nuclei with high microphytoplankton densities (0 .5-1.5 106 cellsI"1) dominated the deep north western and shallow eastern parts of Magdalena Bayduring winter and spring (Figure 4). They are clearly correlated with the nutrient-richwater pockets (Figures 2 and 3), described by Alvarez et al. (1975). The absence ofhigh nutrient concentrations and dense microphytoplankton assemblages close to theopen sea entrance of Magdalena Bay indicates that these phenomena are autogenic andare not caused by processes outside the Magdalena lagoon system. The mineralisationof organic material from nearby mangrove areas in the channels and on the eastern

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part of Magdalena Bay might be a possible source of the high nutrient concentrations(Figure 1).

Close to the entrance of the northern channels, microphytoplankton concentrationswere high (250 — 750 103 cells I"1) from late spring till early summer; temperatureswere low during the same period in this region (Figure 3), indicating the penetrationof cold water masses. Microphytoplankton densities in the channels were generally low(<50 103 cells I"1), while the same held true for Almejas Bay. In the studies of Durbinet al. (1975), McCarthy et al. (1974) and Wattling et al. (1979), short micro-phytoplankton outbursts of 5 — 10 106 cells I"1 were recorded. The difference induration of the high microphytoplankton densities between those waters and theMagdalena Bay lagoon system is striking; a possible explanation might be the differencein nutrient availability mechanisms and flushing rates.

The similarity indices of the microphytoplankton species composition during differentsampling periods were grouped in Treillis diagrams (Table II); shown are the Septemberand January results characteristic of the summer/autumn and winter/spring distribution,

Table n . Examples of the Treillis diagrams of the similarity indices showing the September (A) and January(B) situation, respectively

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respectively. Based on the similarity indices of the microphytoplankton species com-position during different sampling periods (Table II), the Magdalena lagoon complexcould be divided into eight areas (Figure 6). The composite successional pattern, theaverage biomass and the average diversity of each area are shown in Tables I and m,respectively.

The two main areas are the northern, central and southern parts of Magdalena Bayand Almejas Bay (Figure 6, III and VII), covering —70% of the investigated area.Both have a clear succession, biomass and diversity pattern: during winter denseGuinardia flacdda blooms completely dominate both areas, being replaced in spring

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Y1II

Fig. 6. Main areas with specific microphytoplankton assemblages of the Magdalena Bay lagoons.

Table III. Average diversity of the microphytoplankton of the different areas of the Magdalena Bay lagoons

Area

IIIHIIVVVIVIIVIII

Sep.

3.183.163.424.233.410.591.582.02

Nov

2.751.822.484.044.091.012.362.85

Jan

4.322.312.563.200.821.652.912.48

Mar

2 811.642.133.661.750.430.612.11

May

3.360.950.462.710.071.010.420.30

June

3.870.570.240.280.651.031.863.37

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by Rhizosolenia alata; the diversity during these seasons was low. In summer and autumnthe microplankton species composition diverged in both areas, as well as their biomassand diversity: a very sparse, uniform population of Nitzschia sp.l dominated AlmejasBay (Figure 6, VII); in Magdalena Bay (Figure 6, III) a diverse community prevailedduring summer with Eucampia zoodiacus dominant. During autumn both communitieswere replaced by the winter dominant G. flaccida, while simultaneously the cell den-sities increased and the diversity decreased. On the eastern shallow sides of MagdalenaBay and Almejas Bay, partly different microphytoplankton assemblages occurred (Figure6, V and VI), consisting of a mixture of the area ID and VII communities with inter-mittent short outbursts of R. alata and Schizothrix mexicana populations; cell densitiesand diversities of these areas were similar to those of Magdalena Bay and Almejas Bay.In the northern and southern channels (Figure 6, II and VIII) chaotic composite pat-terns prevailed: a series of/?, alata, Nostoc spumigena and S. mexicana blooms, mix-ed with tychopelagic components such as Biddulphia mobiliensis and Melosira sulcatacharacterized these zones. The additional penetration of outside water, both from theinner parts of the lagoon and from the open sea, caused the irregular presence of speciessuch as Chaetoceros curvisetus and G. flaccida; microphytoplankton densities wereconsistently low, while the diversity fluctuated frequently. At the entrances of the nor-thern channels and of Magdalena Bay two very diverse, quite different microplanktoncommunities were recorded (Figure 6,1 and IV). A large number of Chaetoceros speciesdominated both areas, enriched by a number of dinoflagellates such as Ceratiumfurca,C. fusus, C. tripos and by a wide score of neritic species such as Bacteriastrumdelicatulum, Ditylum brightwelli, Nitzschia closterium, Coscinodiscus eccentricus, C.wailesii, Skeletonema costatum and Thalassionema nitzschioides. The successionalspecies composition pattern in both areas was obscure; this was further enhanced bythe presence of a number of typical lagoon species like Biddulphia mobiliensis, G. flac-cida and R. alata occasionally. Cell densities were always low in area IV, while inareas I high concentrations were recorded especially during winter and spring.

The paucity of information on microphytoplankton year cycles in this part of the worldmakes comparison very limited. Smayda (1963, 1966) recorded, in the Gulf of Panamaduring upwelling periods, stable composite successional patterns during a 3-year survey.Both the cell densities of the microphytoplankton and the duration of the upwellingperiod coincided very well with those found in Magdalena Bay (Figure 6, HI); the speciescomposition however was quite different, indicating different topographical and hydro-logical properties of both water masses. In a later study at Punta San Hipolito, 300miles north of the Magdalena lagoon system, Smayda (1975) recorded, at the start ofan upwelling period, a set of species quite similar to those recorded at the entrancesof the northern channels and Magdalena Bay (Figure 6,1 and IV); comparison of biomassdata was impossible because the Chaetoceros fraction was omitted at the cell countsby Smayda (1975).

Nienhuis (1981) in his study of the composite successional pattern of the netplanktonof the Ensenada of La Paz, a small, shallow coastal lagoon on the eastern side of BajaCalifornia, obtained results similar to those of the channels and the eastern parts ofMagdalena Bay and Almejas Bay (Figure 6, areas II, VTTI, V and VI). Successionswere quick and irregular, consisting of a mixture of Rhizosolenia species and Schizothrixmexicana, alternated by diverse communities, dominated by Chaetoceros species.

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In previous studies on upwelling processes along the Baja California coast specialattention was given to a supposed Pleuroncopes planipes, Coscinodiscus eccentricusfood relationship by Longhurst et al. (1967). In this study P. planipes was observedcontinually from September through March inside Magdalena Bay close to the entrance(biomass estimation 10 — 50 organisms m~3 at the surface; area 0.5 — 1 km2); C.eccentricus was only recorded once in moderate concentrations in this area. This supportsthe view of Smayda (1975) that no casual food linkage between both organisms exists.

Studies by Romero (1983) on the stomach contents of sardines, caught in theMagdalena lagoon system, reveal that the microphytoplankton plays a major role asa food source for sardines. The annual capture data for sardines are 20 103 tons (Casas,1983) for this lagoon system. An important short-chain carbon pathway in the trophicsystem of these water masses, similar to those of typical upwelling areas, thereforeexists. Besides this, the results showed that the gut contents of the sardines containedsimultaneously components of several microphytoplankton assemblages, clearlydemonstrating quick migratory activities of these fishes.

The high microphytoplankton densities during part of the year in Magdalena Bayindicate elevated primary production in this part of the lagoon system, provoked bythe high nutrient concentrations, as shown by Alvarez et al. (1975).

Acknowledgements

We would like to thank the authorities of CICIMAR (IPN) for making this study possible.

References

Acosta.M. and Lara.J.R. (1977), Resultados fisico-quimicos en un estudio de variacidn diurna en el areacentral de Bahfa Magdalena, BCS, Mexico, Gene. Mar., Mexico, 4(2), 15-24.

Allen.W.E. (1924), Observations on surface distribution of marine diatoms of Lower California in 1922,Ecology, 5. 389-392.

Allen.W.E. (1934), Marine plankton of Lower California in 1931, Boi. Gaz., 95, 485^92.Allen.W.E. (1938), The Templeton Crocker Expedition to the Gulf of California in 1935: the phytoplankton.

Trans. Am. Mwrosc. Soc., 57, 328-335.Alvarez.S , Galindo.A. and Chee.A. (1975). Caracterfsticas hidroqufmicas de Bahfa Magdalena, BCS, Cienc.

Mar., Mexico. 2(2). 94-109.Casas.M. (1983), Distribution en tiempo y espacio de las especies de sardina y macarela en Bahfa Magdalena,

BCS. Medico, M.Sc. Thesis CICIMAR (IPN), Mexico, 168 pp.Cupp.E.E. (1930), Quantitative studies of miscellaneous series of surface catches of marine diatoms and

dinoflagellates between Seattle and the Canal Zone from 1924 to 1928, Trans. Am. Microsc. Soc., 49,238-245.

Cupp.E.E. (1934), Analysis of marine plankton diatom collections taken from the Canal Zone to Californiaduring March 1933, Trans. Am. Microsc. Soc., 53, 22-29.

Cupp.E.E. (1943), Marine plankton diatoms of the West coast of North America, Bull. Scripps Inst. Oceanogr.,5. 1-238.

Cupp.E.E. and Allen.W.E. (1938), Plankton diatoms of the Gulf of California obtained by the Allen Han-cock Pacific Expedition of 1937. Allen Hancock Found. Pacific Exped., 3, 61-99.

Durbin.E.G., Krawiec.R.W. and Smayda.T.J. (1975), Seasonal studies on the relative importance of dif-ferent size fractions of phytoplankton in Narragansett Bay (USA), Mar. Biol., 32, 271-287.

Dussart.B.H. (1965). Les differentes categories de plancton, Hydrobiologia, 26, 72-74.GilbertJ.Y. and Allen.W.E. (1943), The phytoplankton of the Gulf of California obtained by the "E.W.

Scripps' in 1939 and 1940. J. Mar. Res.. 5, 89-110.Gilmartin.M.N. and Revelante.N. (1978). The phytoplankton of the barrier island lagoons of the Gulf of

California. Estuar. Coast. Mar. Sci.. 7. 29-47.

440

at Duke U



ownloaded from



Humm.H.J. and Wicks,S.R. (1980), Introduction and Guide to the Marine Blue Green Algae, John Wileyand Sons, New York, USA, 194 pp.

Lankford.R.R. (1977), Coastal lagoons of Mexico. Their origin and classification, in Wiley,M.L. (ed.),Estuarine Processes, 2, Academic Press, New York, USA, pp. 182-216.

Licea.S. (1974), Distribuci6n de diatomeas de la laguna de Agiobampo, An. Cent. Cienc. Mar Limnol.,Univ. Nac., 1(1), 99-131.

Longhurst.A.R., Lorenzen,C.J. and Thomas,W.H. (1967), The role of the pelagic crabs in the grazing ofphytoplankton of Baja California, Ecology. 48, 190-200.

Malone.T.C. (1971a), The relative importance of nanoplankton and netplankton as primary producers intropical oceanic and neritk plankton communities, Limnol. Oceanogr., 16, 633-639.

Malone.T.C. (1971b), The relative importance of nanoplankton and netplankton as primary producers inthe California Current system, Fish. Bull., 69, 799-820.

Malone.T.C. (1980), Algal size, in Morris.J. (ed.), The Physiological Ecology of Phytoplankton. BlackwellScientific Publications, Oxford, UK, pp. 433-463.

McCarthy J.J. , Rowland,W. and Loftus.M.E. (1974), Significance of nanoplankton in the Chesapeake Bayestuary and problems associated with the measurement of nanoplankton productivity, Mar. Bio., 24, 7-16.

Nienhuis.H. (1981), Some aspects of the phytoplankton ecology of the Ensenada of La Paz, BCS, Mexico,Mem. Vth CIBCASIO Symp., 5, 121-135.

Nienhuis.H. (1982), Phytoplankton characteristics of the southern part of the Gulf of California, Mem. VlthCIBCASIO Symp., 6, 152-186.

Romero,N. (1984), Analfsis del contenido estomacal de las sardinas y macarelas de Bahfa Magdalena, Mexico,M.Sc.Thesis, Instituto Politecnico Nacional, Mexico.

Round,F.E. (1967), The phytoplankton of the Gulf of California. Part I. Its composition, distribution andcontribution to the sediments, J. Exp. Mar. Biol. Ecol., 1, 76-97.

SchillerJ. (1933), Dinoflagellatae (Peridineae) in monographischer Behandhing, in Rabenhorst.L. (ed.), Krypto-gamen Flora von Deutschland, Osierreich und der Schweiz, 3(1), 617 pp.

Schiller ,J. (1937), Dinoflagellatae (Peridineae) in monographischer Behandlung, in Rabenhorst.L. (ed.), Krypto-gamen Flora von Deutschland, Osierreich und der Schweiz, 3(2), 589 pp.

Smayda,TJ. (1963), A quantitative analysis of the phytoplankton of the Gulf of Panama. Results of the regionalphytoplankton surveys during July and November 1957, and March 1958, Bull. Int. Am. Trop. Tuna Comm..7, 191-253.

Smayda.T.J. (1966), A quantitative analysis of the phytoplankton of the Gulf of Panama. ID. General ecologicalconditions and the phytoplankton dynamics at 8°45'N and 79°23'W from November 1954 to May 1957,Bull. Int. Am. Trop. Tuna Comm., 11, 354-612.

Smayda.T.J. (1975), Net phytoplankton and the greater than 20 micron size fraction in upwelling watersoff Baja California, Fish. Bull., 73, 38-50.

StanderJ.M. (1970), Diversity and similarity of benthic fauna off Oregon, M.Sc. Thesis Oregon State Univer-sity, USA, 72 pp.

Taylor.F.J.R. (1976), Dinoflagehates from the International Indian Ocean Exhibition, E.SchweizerbarfscheVerlagsbuchhandlung, Stuttugart, FRG, 243 pp.

Yentsch.C.S. (1959), Relative significance of the netplankton and nanoplankton in the waters of VineyardSound, J. Cons. Perm. Intern. Explor. Mer, 24, 231-238.

Wattling,L., Bottom,D., Pembroke,A. and Maurer.D (1979), Seasonal variations in Delaware Bay phyto-plankton community structure, Mar. Bio., 52, 207-215.

Zeitzschel.B. (1970), The quantity, composition and distribution of suspended paniculate matter in the Gulfof California, Mar. Biol., 16, 305-318.

Received November 1983; accepted April 1985

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a quantitative analysis of the annual phytoplankton cycle of the magdalena lagoon complex (mexico)

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