SHALLOW LAKES

Periphytic algal community adaptive strategies in N and Penriched experiments in a tropical oligotrophic reservoir

Carla Ferragut • Denise de Campos Bicudo

Published online: 12 March 2010

� Springer Science+Business Media B.V. 2010

Abstract This study aimed at evaluating periphytic

algae adaptive strategies, including size class,

growth, and adherence forms, and the CRS functional

groups model under nitrogen and phosphorus artifi-

cial enrichment in a Brazilian tropical shallow and

oligotrophic reservoir. Four treatments were designed

using enclosures (n = 3) filled with 185 L of

reservoir water: control (no nutrient addition),

P? (isolated P addition, N-limiting condition); N?

(isolated N addition, P-limiting condition); and NP?

(combined addition, no limitation). N:P ratios were

maintained throughout the experiment. Glass slides

were used for periphyton growth, and sampling cam-

paigns were carried out at short regular intervals (3–5

days) over a 31-day succession. Enrichment favored

replacement of flagellates and loosely attached (mobile)

forms by firmly attached mainly prostrate and entangled

forms over succession. Isolated or combined P addition

favored C–S-strategists green algae, whereas P limita-

tion kept R-strategists over succession, promoting

R-Cyanobacteria under high P limitation. Our results

were supported by the species density and biovolume

due to the dominance of small size classes (small-

sized classes) in the community (nano and picoperi-

phyton). Overall, only the CRS strategies were more

predictive of the experimental nutritional conditions.

Keywords Periphyton � Functional groups �Adaptive strategies � Enrichment

Introduction

Studies on adaptive strategies do not undermine the

usefulness or the need of species level ecological

studies. They emphasize the importance of examining

some approaches at the community level, such as

structuring process, diversity, dominance, relative

abundance, and paleoecology on the functional group

perspective (Steneck & Dethier, 1994). In this respect,

functional groups provide a simplified approach to the

structural and functional components of communities

(Steneck & Dethier, 1994; McIntire et al., 1999;

Fonseca & Ganade, 2001). A functional group is

defined as a set of species exhibiting similar responses

to environmental conditions and having similar effects

on the dominant ecosystem processes (Fonseca &

Ganade, 2001). Considering algal community, this

term also expresses species co-occurrences, which

respond to environmental conditions similarly

(Reynolds et al., 2002).

Guest editors: M. Meerhoff, M. Beklioglu, R. Burks, F. Garcıa-

Rodrıguez, N. Mazzeo & B. Moss / Structure and Function of

World Shallow Lakes: Proceedings from the 6th Shallow Lakes

Congress, held in Punta del Este, Uruguay, 23–28 November,

2008

C. Ferragut (&) � D. de Campos Bicudo

Ecology Section, Instituto de Botanica, Caixa Postal 3005,

Sao Paulo, SP 01061-970, Brazil

e-mail: carlaferragut@yahoo.com.br

123

Hydrobiologia (2010) 646:295–309

DOI 10.1007/s10750-010-0168-0

Based on the growth logistic equation, McArthur &

Wilson (1967) proposed the r and k selection strategies,

which were thoroughly discussed by Pianka (1970) and

applied to phytoplankton (Reynolds, 1984; Kilham &

Hecky, 1988; Arauzo & Cobelas, 1994). In studies of

terrestrial plants, Grime (1977) expanded the r–k

selection strategies by proposing the CRS model

theory (C: competitive strategy, R: ruderal strategy,

S: stress-tolerant strategy) to explain species distribu-

tion. Reynolds (1988) adapted the CRS model to

explain phytoplankton distribution patterns, which has

been applied with success (e.g., Huszar et al., 2000).

Later on, the CRS functional group theory was applied

to periphyton, based on algae adaptive strategies

(McCormick, 1996; Biggs et al., 1998).

McCormick (1996) described a four-ecological

strategy model considering the adaptive strategies of

periphytic algae along gradients of nutrient availabil-

ity and disturbance intensity. It consists of C:

competitors adapted to maximize resource capture

and growth rate; S: stress-tolerant species; D: distur-

bance-resistant species possessing morphological

adaptations that prevent removal by scouring or

herbivory; and R: ruderal species adapted for colo-

nizing disturbed sites where resource supply rates are

high and density-independent interactions are weak.

Biggs et al. (1998) used CRS functional group

(Grime, 1977) and the dynamic equilibrium theory

(Huston, 1979) for proposing a conceptual model of

habitat matrix for periphyton communities in

unshaded temperate streams. The strategies suggested

by Biggs et al. (1998) were: C (competitive) more

competitive algae in eutrophic and steady systems;

C–S: more competitive algae in mesotrophic and

steady systems; S (stress-tolerant): more competitive

algae in oligotrophic and steady systems; and R

(ruderal species): more competitive algae in meso-

trophic systems with frequent disturbances. This

model has recently been applied with success to

periphyton in order to characterize environmental

gradients in subtropical lentic systems (Carrick &

Steinman, 2001), subtropical lotic systems (Burliga

et al., 2004) and for evaluating the colonization

process in temperate lotic systems (Acs et al., 2000).

However, the discussion of the potentiality to use the

CRS model for periphyton is still incipient world-

wide, and particularly in tropical regions.

Species classification in the CRS strategies

depends on the evaluation of their adaptive traits,

which also provides information about changes in

community structure due to environmental condi-

tions. The algal adaptive strategies more commonly

associated to environmental alterations are changes in

size classes (Sprules & Munawar, 1986; Kamenir

et al., 2004), growth forms (Margalef, 1978;

Reynolds, 1997), and adherence forms mainly for

attached community. For periphyton, Cattaneo et al.

(1995) observed that changes in algal size distribution

and growth forms could be indicative of the system’s

trophic state (Cattaneo, 1987) and contamination

(Cattaneo, 1992). Pringle (1990) reported that diatom

functional groups responded differently to river

enrichment. Therefore, although scarce, studies on

periphyton may strongly indicate the response of

adaptive strategies to environmental alterations.

This study aimed at evaluating periphytic algae

adaptive strategies, including growth forms, size

class, and adherence forms, as well as CRS functional

groups model under nitrogen and phosphorus artifi-

cial enrichment in a tropical oligotrophic shallow

reservoir, and in doing so to contribute to a better

understanding of the adaptive strategies in response

to nutrient enrichment in ecosystems.

Materials and methods

Study area

IAG Reservoir is located in the reserve of Parque

Estadual das Fontes do Ipiranga (Sao Paulo, south-

eastern Brazil). This shallow reservoir is oligotrophic,

has a surface area of 11,270 m2, a volume of

76,653 m3, a mean depth of 1.5 m, a maximum

depth of 4.7 m, and a mean theoretical residence time

of 9.5 days (Bicudo et al., 2002). Ammonium, nitrate,

and soluble reactive phosphorus concentrations on an

annual average basis are 28.3, 6.2, and \9.3 lg l-1,

respectively (Bicudo et al., 2002).

Experimental design

The mesocosms (12 polyethylene bags isolated from

sediments and filled with 185 l of reservoir water)

were installed in the littoral region of the reservoir in

July/1996 (winter). Two wooden containing 50 glass

slides each were placed inside each mesocosm as

substrate for periphyton growth.

296 Hydrobiologia (2010) 646:295–309

123

Triplicate treatments were established as follows:

control (no nutrient addition); P? treatment (isolate

phosphorus addition, N-limiting condition); N? treat-

ment (isolate nitrogen addition, P-limiting condition);

and NP? treatment (nitrogen and phosphorus com-

bined addition, good availability of nutrients). Nutri-

ents added were ammonium nitrate and potassium

dihydrogen phosphate (NH4NO3 and KH2PO4 Merck

PA, respectively), according to Redfield N:P molar

ratio to establish nutrient availability (Redfield, 1958).

Based on a previous analysis of reservoir water,

dissolved inorganic nitrogen concentration was

12 lmol DIN l-1 and soluble reactive phosphorus

was below the method detection limit (\0.11 lmol

P l-1). Therefore, to reach a great nutrient availability

level (N:P ratio = 10–16) in the treatment NP?,

20 lmol N l-1 and 2 lmol P l-1 was added on the

first day of the experiment. To the N? treatment

20 lmol N l-1 was added to establish the P-limiting

condition (N:P ratio [16), and to the P? treatment

2 lmol P l-1 were added to establish the N-limiting

condition (N:P ratio\10). After this first enrichment,

the preestablished conditions were maintained

throughout the experiment by daily water monitoring

and additional enrichment to adjust N:P ratios

(Table 1). Enclosure volume was checked daily.

Sampling and limnological variables

Regular sampling of abiotic and biological variables

were carried out every 3 days up to the 15th day of

periphyton succession, and then at 5-days intervals

until day 31 (3, 6, 9, 12, 15, 20, 25, and 31 days of

succession).

The following variables were measured on the

sampling days: temperature, electric conductivity

(Digimed), pH (pHmeter Jenway), water transparency

(Secchi disc), alkalinity (Golterman & Clymo, 1971),

dissolved oxygen (Golterman et al., 1978), dissolved

inorganic carbon, nitrite and nitrate (Mackereth et al.,

1978), amnonium (Solorzano, 1969), orthophosphate

(SRP) and total dissolved phosphorus (TDP)

(Strickland & Parsons, 1965). The samples were kept

under refrigeration until getting to the laboratory

(800 m from the sampling site). On the sampling

day, water samples were filtered under low pressure

(\0.3 atm) through Whatman GF/F membrane filters

for analyses of dissolved nutrients and phytoplankton

chlorophyll-a. Unfiltered water samples were used for

total nitrogen (TN) and total phosphorus (TP) deter-

minations (Valderrama, 1981) within at most 30 days

from the collecting date.

Carlson’s trophic state index (TSI) modified by

Toledo (1990—internal report, in Bicudo et al., 2006)

was calculated for each treatment based on the average

of total phosphorus and phytoplankton chlorophyll-a

measured over the entire studied period. Water trans-

parency was not included since it was not measured in

the mesocosms. This index was an adaptation of the

original Carlson’s (1977) trophic index to tropical

systems and was considered the most appropriate one

for tropical reservoirs according to the TSI study

carried out by Bicudo et al. (2006).

Periphyton was collected by random sampling of

glass slides, and removed from the substrate by

scraping and rinsing with distilled or ultrapure water.

All biological analyses were carried out at most

within 8 months from the collecting date.

Samples for quantitative periphyton analyses were

adjusted to a constant volume with distilled water and

preserved with acetic lugol solution at a final

concentration of 0.5%, and immediately stored in

darkness at room temperature. Algal quantifications

were performed under a Zeiss Axiovert microscope

Table 1 N and P amendments in each treatment during the experimental period to maintain the preestablished P-limiting condition

(N?), N-limiting condition (P?), and good availability of nutrients (NP? treatment)

Enrichments N? treatment P? treatment NP? treatment

Succession day N addition

(lmol l-1)

P addition

(lmol l-1)

N addition

(lmol l-1)

P addition

(lmol l-1)

Initial 20 2 20 2

T0 (substrate exposure) 20 10 20 10

T4 10 0.5 10 0.5

T11, T14, T17, T19, T22, T24, T27, T29 20 0.5 20 0.5

Hydrobiologia (2010) 646:295–309 297

123

(9400) according to Utermohl (1958), and sedimen-

tation time in chamber following Lund et al. (1958).

Counting limit was established according to the

species rarefying curve and until reaching 100

individuals of the most common species (Bicudo,

1990). Biomass (lm3 cm-2) was estimated using the

biovolume obtained by multiplying each species’

density by the mean volume of its cells considering,

whenever possible, the mean dimension of 30 indi-

viduals, following Sun & Liu (2003) and Hillebrand

et al. (1999).

Taxonomic material was preserved with 4%

formaldehyde water solution, and diatom permanent

slides followed Hasle & Fryxell (1970).

Periphytic algae were classified according to the

following criteria:

• Growth forms: unicellular, flagellate, filamentous,

and colonial (Graham & Wilcox, 2000).

• Forms of adherence to substrate: firmly adhered

and loosely adhered. Algae with some locomotion

mechanism were classified as loosely attached,

and those without locomotion structure and with

fixation structure were classified as firmly

attached (Sladeckova & Sladecek, 1964, 1977).

• Attached forms were further subdivided into

mobile, entangled (loosely attached), and pros-

trate, heterotrichous and stalked forms (firmly

attached) (Biggs et al., 1998).

• Size class: picoperiphyton (0.2–2 lm), nano-

periphyton (2–20 lm) and microperiphyton

(20–200 lm). This classification was based on

phytoplankton size classes (Reynolds, 1997).

• CRS strategists sensu Biggs et al. (1998). The

following attributes were considered for algal

classification: adherence forms to substratum,

growth forms, cellular size, reproduction type,

resistance degree to physical disturbances, nitro-

gen fixation, maximum biomass and specific

growth (based on the literature data).

Data statistical treatment

Descriptive and exploratory univariate analysis was

performed using the software STATISTICA 9 for

Windows. One-way ANOVA (a = 0.05) was applied

to test significant differences among treatment means

(nutrients). For the CRS strategist algae (density and

biovolume), that analysis was performed for the more

advanced successional stage (31st day). Specific

means were compared to each other using Tukey’s

multiple-comparison test (a = 0.05). Multivariate

analysis was processed by applying principal com-

ponent analysis (PCA) to the biotic data, using a

covariance matrix with data transformed by log

(x ? 1). Software PC-ORD version 3.0 for windows

McCune & Mefford (1999) was used for the

analysis.

Results

Abiotic variables

Table 2 summarizes physical and chemical variables

of each treatment (n = 3) during the experimental

period. Phosphorus concentrations were the highest in

P? and NP? treatments, while in the control and

treatment N? the concentration was below or near

the method detection limit (\4 lg l-1) (Fig. 1A).

SRP concentration did not differ between P? and

NP? treatments (ANOVA: F = 1.63; P = 0.2223),

although significant difference was detected consid-

ering TP levels (ANOVA: F = 64.73; P = 0.0000).

Dissolved inorganic nitrogen (DIN) concentration

was higher in N? and NP? treatments (Fig. 1B), and

it was significantly different in both treatments

(ANOVA: F = 15.19; P = 0.0002).

According to the Redfield N:P ratio, the mean

values for N:P molar ratio (DIN:SRP) confirmed

P-limiting condition in N? treatment (332), N-limit-

ing condition in P? treatment (2) and good availability

of nutrients in NP? treatment (10) (Fig. 1C).

The trophic state index classified control and N?

treatments as oligotrophic, and P? and NP? treat-

ments as meso-eutrophic (Table 2).

Biological variables

Periphyton dominant growth form in the control

was flagellate (85–96%), and amendments clearly

increased the diversity of forms (Fig. 2A–E). Com-

pared with the control, in N? and P? treatments, there

was an increase in unicellular form and over succession

an increase in filamentous (20–37%) and colonial

forms (20-30%), respectively. In NP? treatment,

flagellates were dominant up to the 20th day

(51–88%), being outnumbered by colonial algae

298 Hydrobiologia (2010) 646:295–309

123

Ta

ble

2L

imn

olo

gic

alp

aram

eter

ran

ges

and

,b

etw

een

par

enth

eses

,m

ean

,st

and

ard

erro

rs(n

=3

6),

and

coef

fici

ent

of

var

iati

on

(%)

inn

utr

ien

tad

dit

ion

trea

tmen

ts

Var

iab

leC

on

tro

lN

?tr

eatm

ent

P?

trea

tmen

tN

P?

trea

tmen

t

Tem

per

atu

re(o

C)

14

.2–

17

.5(1

5.6

±0

.3;

5.2

%)

14

.2–

17

.5(1

5.6

±0

.3;

5.2

%)

14

.2–

17

.5(1

5.6

±0

.3;

5.2

%)

14

.2–

17

.5(1

5.6

±0

.3;

5.2

%)

Ele

ctri

cco

nd

uct

ivit

y(l

Scm

-1)

36

.0–

46

.6(3

9.6

±1

.2;

9.4

%)

37

.5–

58

.9(4

4.8

±2

.4;

16

.0%

)3

7.1

–6

.2(3

9.6

±0

.8;

6.2

%)

38

.4–

58

.3(4

3.8

±2

.3;

15

.4%

)

Dis

solv

edo

xy

gen

(mg

l-1)

7.5

–8

.9(8

.2±

0.2

;6

.4%

)6

.8–

9.0

(8.1

±0

.2;

8.1

%)

6.5

–1

0.1

(8.5

±0

.5;

15

.9%

)7

.0–

10

.2(8

.9±

0.4

;1

4.1

%)

HC

O3-

(mg

l-1)

3.6

–6

.5(4

.5±

0.8

;5

.7%

)3

.5–

4.4

(4.0

±0

.3;

6.9

%)

4.2

–6

.6(5

.0±

0.7

;1

4.9

%)

3.0

–4

.3(3

.7±

0.6

;6

.0%

)

Fre

eC

O2

(mg

l-1)

4.1

–1

0.1

(7.2

±1

.9;

26

.3%

)6

.9–

13

.9(±

2.1

–4

.4;

22

.8%

)2

.1–

12

.5(±

3.7

–1

.7;

58

.6%

)2

.2–

12

.9(±

2.8

–2

.8;

35

.5%

)

pH

5.9

–6

.5(6

.1±

0.2

;3

.0%

)5

.8–

6.1

(5.9

±0

.1;

1.6

%)

5.8

–6

.7(6

.3±

0.4

;6

.0%

)5

.7–

6.6

(6.0

±0

.3;

4.3

%)

SR

P(l

gl-

1)

\4

\4

58

–1

44

(87

±1

0;

33

.0%

)3

3–

10

6(7

1±

8;

32

.0%

)

PD

T(l

gl-

1)

\4

\4

61

–1

41

(92

±9

;3

0.7

%)

40

–1

11

(78

±9

;3

2.8

%)

TP

(lg

l-1)

\4

–1

3(8

±1

;4

3.7

%)

\4

–1

0(7

±1

;4

1.3

%)

85

–1

64

(10

9±

10

;2

8.6

%)

75

–1

48

(10

1±

9;

27

.9%

)

N-N

O2-

(lg

l-1)

1–

4(2

±0

.3;

38

.7%

)1

–9

(3±

1;

69

.4%

)1

–2

(1±

0.1

;2

8.2

%)

1–

10

(4±

1;

75

.7%

)

N-N

O3-

(lg

l-1)

\8

–9

1(3

4±

11

;9

6.7

%)

10

–2

21

(69

±2

2;

93

.2%

)\

8–

68

(20

±9

;1

27

.6%

)\

8–

16

8(6

2±

19

;8

9.8

%)

N-N

H4?

(lg

l-1)

62

–1

78

(95

±1

5;

46

.3%

)1

76

–8

76

(41

7±

88

;6

3.1

%)

17

–8

7(3

3±

8;

70

.8%

)1

09

–6

24

(23

1±

58

;5

7.6

%)

DIN

(lg

l-1)

73

-18

1(1

11

±2

5;

27

.1%

)2

25

–8

93

(48

8±

12

9;

45

.3%

)1

4.3

–1

56

(58

±2

5;

65

.7%

)1

57

–6

39

(29

6±

90

;5

2.6

%)

TN

(lg

l-1)

17

9–

41

6(2

87

±2

7;

23

.8%

)3

92

–1

.49

9(7

19

±1

14

;4

7.7

%)

13

3–

24

9(2

08

±1

4;

19

.7%

33

0–

1.1

09

(53

5±

77

;4

3.2

%)

So

lub

lere

acti

ve

sili

ca(m

gl-

1)

0.8

3–

1.0

9(0

.95

±0

.03

;1

0.1

%)

0.8

1–

1.0

0(0

.90

±0

.02

;6

.2%

)0

.74

–0

.98

(0.8

8±

0.0

2;

8.0

%)

0.8

1–

0.9

9(0

.88

±0

.02

;7

.5%

)

Ph

yto

pla

nk

ton

chlo

rop

hy

ll-a

(lg

l-1)

0.3

4-3

.82

(1.5

2±

1.2

7;

83

.9%

)0

.41

-5.2

5(2

.47

±1

.96

;7

9.3

%)

0.8

3–

20

.07

(7.4

±6

.44

;8

2.8

%)

0.5

4–

24

.53

(10

.4±

8.6

4;

83

.1%

)

N:P

mo

lar

rati

o(D

IN:S

RP

)5

5.9

–1

21

.6

(88

.8±

24

.0;

27

.1%

)

15

2.6

–6

07

.2

(33

2±

15

0.4

;4

5.3

%)

0.4

–4

.0(1

.8±

1.1

;6

0.3

%)

6.1

–1

5.0

(9.7

±3

.0;

32

.2%

)

Car

lso

n’s

tro

ph

icst

ate

ind

ex

mo

difi

edb

yT

ole

do

22

.9–

37

.0(2

9.0

±4

.4;

15

.2%

)2

4.0

–4

4.7

(35

.3±

56

.4;

18

.1%

)4

1.9

–6

0.5

(50

.4±

5.8

;1

1.6

%)

43

.2–

63

.7(5

5.9

±7

.0;

12

.5%

)

Hydrobiologia (2010) 646:295–309 299

123

(35-39%) during latter colonization phase. Enrichment

increased participation of other growth forms,

although without characterizing the type of enrichment

(Fig. 2A).

Nanoperiphyton was the dominant size class in the

control, P? and NP? treatments, with mean contri-

butions of 84, 72, and 90%, respectively (Fig. 2B).

Isolated N addition (N?) favored picoperiphyton

(60% contribution), and high phosphorus availability

increased 5 (P?) and 3 (NP?) times microperiphyton

contribution. A marked change was observed under

severe P limitation (N? treatment).

In relation to the control, isolated and combined

enrichments changed the contribution of adherence

forms (Fig. 2C), favoring attached mainly prostrate

forms (Fig. 2D).

Participation of CRS adaptive strategies changed

according to treatment (Fig. 2E). In control and N?

treatment, R-strategists prevailed throughout almost

the entire succession period, while isolated and

mainly combined P addition promoted larger contri-

bution of C–S-strategists (76 and 94%, respectively).

Initial colonizers were R-strategists in all treatments,

except for NP? treatment, and later on being

0

200

400

600

800

1000

1200

12 15 20 25 31 12 15 20 25 31 12 15 20 25 31 12 15 20 25 31

DIN

(µg

L-1

)

B

0

50

100

150

200

SRP

(µg

L-1)

A Control N+ P+ NP+

0

200

400

600

800

12 15 20 25 31 0 12 15 20 25 31

N:P

mol

ar r

atio

C

0

4

8

12

16

20

12 15 20 25 31

0 3 6 9 0 3 6 9 0 3 6 9 0 3 6 9

0 3 6 9 3 6 9 6 9 0 3 60 3 9 12 15 20 25 31

Days

Fig. 1 Temporal variation of SRP (A, mean ± SE), dissolved inorganic nitrogen concentration (B, mean ± SE), and N:P molar

ratio (C, mean ± SE) in nutrient addition treatments (C = control, P?, N?, NP?)

300 Hydrobiologia (2010) 646:295–309

123

0%

20%

40%

60%

80%

100%

Gro

wth

for

m

Unicelular Colonial Filamentous Flagellate

Control NP+P+N+A

0%

20%

40%

60%

80%

100%

Cel

lula

r Si

ze

Microperiphyton Nanoperiphyton Picoperiphyton

B

0%

20%

40%

60%

80%

100%

Atta

chm

ent

Firmly adhered Loosely adhered

C

0%

25%

50%

75%

100%

Form

s of

adh

eren

ce

Entangled Heterotrichous Mobile Stalked Prostrate

D

0%

20%

40%

60%

80%

100%

12 15 20 25 31 12 15 20 25 31 12 15 20 25 313 6 9 3 6 9 3 6 9 3 6 9 12 15 20 25 31

Days

Stra

tegi

sts

C-R

-S

C C-S R S

E

Fig. 2 Relative density of growth forms (A), size classes (B), adherence forms (C), adherence type (D), and periphytic algal CRS

adaptive strategies (E) in nutrient addition treatments (C = control, P?, N?, NP?)

Hydrobiologia (2010) 646:295–309 301

123

replaced by C–S-strategists in advanced stages. In

NP? treatment C–S-strategists prevailed during suc-

cession. Although C-strategist density was always

low in comparison to control, P addition (P?, NP?)

considerably increased (229 and 110 times, respec-

tively) the representation of this group.

Species richness increased over succession, mainly

under isolated and combined P addition (2–2.5 times

higher than control) (Fig. 3A). Positive and signifi-

cant Pearson correlation was found between richness

and C-, C–S- and R-strategists in control (r = 0.7)

and NP? treatments (r = 0.6–0.8). In P? treatment,

positive correlation was significant for C–S- and

R-strategists (r = 0.8), while in N? treatment it was

only significant for R-strategist (r = 0.8). Thus,

while species richness enhanced over succession,

the adaptive strategies were selected by treatments.

Considering density (Fig. 3A) and biomass

(Fig. 3B), CRS adaptive strategies followed the main

successional variation trend. Thus, C–S-strategists

exponentially increased over succession, prevailing

under isolated and combined P addition. However, in

N? treatment R-strategists were better represented in

density than in biovolume. In addition, at the end of

succession C–S-strategists were better represented in

density in the control, while C-strategists were in

biomass. As for the last day of the successional stage

(31st day), C–S-strategists density (Fig. 4A) and

biovolume (Fig. 4B) were significantly higher under

isolated and combined P addition (Tukey’s test,

0

500

1000

1500

2000

20 2515 12 15 20 25 31

C-R

-S s

trat

egie

s

(103

ind

cm-2

)

0

20

40

60

80

Spec

ies

Ric

hnes

s

C C-S R S Richness

Control N+ P+ NP+A

0

200

400

600

800

3 6 9 12 31 20 25153 6 9 12 31 20 25153 6 9 12 31 3 6 9

20 2515 12 15 20 25 313 6 9 12 31 20 25153 6 9 12 31 20 25153 6 9 12 31 3 6 9

C-

R-S

str

ateg

ies

(105

3µm

cm

-2)

C C- R S

B

Fig. 3 Mean algal species richness (A) and periphyton CRS adaptive strategies as density (A) and biovolume (B) during succession

in nutrient addition treatments (C = control, P?, N?, NP?)

302 Hydrobiologia (2010) 646:295–309

123

Anova—density: F = 25.50; P = 0.0004; biovo-

lume: F = 162.29; P = \ 0.0001), and were differ-

ent between both treatments. R-strategists did not

differ between C, N?, and P? treatments, decreasing

under combined addition of nutrients (Tukey’s test,

Anova—density: F = 13.67; P = 0.0021; biovo-

lume: F = 9.44; P = 0.0058). Although little repre-

sented in periphyton, C-strategists differed between

treatments (Tukey’s test, Anova—density: F =

159.92; P = 0.0001; biovolume: F = 8465.48; P =

\ 0.0001), and S-strategists only differed in density

(Tukey’s test, Anova—density: F = 18.69; P =

0.0009; biovolume: F = 3.91; P = 0.054).

Periphyton algae comprised 155 specific and

infraespecific taxa, belonging to 11 classes, 19 orders,

and 89 genera. Among them, only 19% (29) were

common to all treatments.

Species with mean density higher than 3% of total

density over the experimental period were considered

species descriptors (Fig. 5; Table 3). Without enrich-

ment, Chromulina elegans, Chlamydomonas sordida,

Chlamydomonas epibiotica, Chloromonas pumilio,

and Cryptomononas erosa presented high density,

mainly towards later successional stages. Under N?

addition, Chromulina elegans and Chroococcus

minor prevailed around the 20th day, being later on

outnumbered by Eunotia bilunaris and Pseudanaba-

ena galeata. Under isolated and combined P addition

(P?, NP?), Chlamydomonas planctogloea, Chla-

mydomonas sordida, Scenedesmus ecornis, and

Monoraphidium arcuatum were the best represented

species. Moreover, P? treatment favored five

additional species (Chlamydomonas sagittula, Mono-

raphidium contortum, Monoraphidium minutum,

Monoraphidium pseudobraunii, and Nitzschia palea).

The kind of enrichment clearly altered the periphyton

community descriptors, promoting replacements

since the beginning of succession.

Principal component analysis (PCA) was carried

out to evaluate the main taxonomic structure varia-

tion (species [1.5% of total density). Analysis

summarized 68.7% of total data variability in their

first two axes (Fig. 6, Table 3). The first component

separated the sampling units from isolated and

combined P addition (right side) from the isolated

N? enrichment (left side), particularly over succes-

sion. Positive side of the axis was strongly correlated

(r = 0.9) with higher density of C–S-strategists

(Scenedesmus ecornis, Scenedesmus spinosus, Chara-

cium rostratum, Monoraphidium arcuatum, Chla-

mydomonas sagittula, and Kirchneriella pinguis) and

one R-strategist (Nitzschia palea). These species

achieved their highest growth towards the end of the

experimental period under P addition (P?, NP?).

Negative side was correlated (r = 0.4) with higher

density of Chloromonas pumilio (R-strategist) and low

Chlorophyceae density in the control and N? treat-

ments. Therefore axis 1 represented a gradient of P

availability, in which mainly C–S-strategists were

associated to P amendments (P?, NP?).

The second component mainly ordered N?

sampling units on the positive side, associated to

R-strategist species (Synechococcus nidulans, Chroo-

coccus minor, Aphanocapsa conferta, and Lemmer-

maniella pallida) (r [ 0.8). The negative side

ordered the sampling units of NP? treatment and

control, associated with higher density of Achnanthi-

dium saprophila (R-strategist) and Chlamydomonas

epibiotica (C–S-strategist) (r [ 0.7). Axis 2 indicated

the higher contribution of Cyanobacteria R-strategists

associated to larger stress of nutritional conditions,

and particularly to severe P limitation (N?).

0

500

1000

1500

2000

2500

3000

P+

Tota

l Den

sity

(1

03 in

d cm

-2)

a a

b

c

aa

ba ab ba b c

A

a

0

200

400

600

800

1000

C N+ NP+

C N+ P+ NP+

Treatment

Tot

al B

iovo

lum

e (

105

µm³ c

m-²

)

C C-S R S

a

a

b

aaa

ba

a

a aa b c

c

B

Fig. 4 Mean (±SD) periphyton CRS adaptive strategies as

density (A) and biovolume (B) at the 31st day of succession in

nutrient addition treatments (C = control, P?, N?, NP?).

Within each adaptive strategy, means that are statistically equal

share a common letter

Hydrobiologia (2010) 646:295–309 303

123

0

10

20

30

40

50 Chromulina elegans

Chlamydomonas planctogloea

Chlamydomonas sordida

Scenedesmus ecornis

Pseudanabaena galeata

0

5

10

15

20

25 Chlamydomonas sagittula

Monoraphiidum arcuatum

Monoraphidium contortum

Nitzschia palea

Scenedesmus spinosus

0

1

2

3

4

5

6

7 Chlamydomonas epibiotica

Chloromonaspumilio

Chroococcusminor

Monoraphidiumminutum

Monoraphidiumpseudobraunii

0

1

2

3

4

3 6 9 12 15 20 25 31 3 6 9 12 15 20 25 31 3 6 9 12 15 20 25 31 3 6 9 12 15 20 25 31 3 6 9 12 15 20 25 31

3 6 9 12 15 20 25 31 3 6 9 12 15 20 21 31 3 6 9 12 15 20 25 31 3 6 9 12 15 20 25 31 3 6 9 12 15 20 25 31

3 6 9 12 15 20 25 31 3 6 9 12 15 20 25 31 3 6 9 12 15 20 25 31 3 6 9 12 15 20 25 31 3 6 9 12 15 20 25 31

3 6 9 12 15 20 25 31 3 6 9 12 15 20 25 31 3 6 9 12 15 20 25 31 3 6 9 12 15 20 25 31 3 6 9 12 15 20 25 31

Days

Den

sity

(10

3 ind

cm-2

)D

ensi

ty (

103 in

d cm

-2)

Den

sity

(10

3 ind

cm-2

)D

ensi

ty (

103 in

d cm

-2)

C N+ P+ NP+

Cyanosarcina sp.

Chloromonasfrigida

Eunotiabilunaris

Lemmermaniella pallida

Cryptomonaserosa

Fig. 5 Mean density of descriptor species ([3% of total density) in nutrient addition treatments (C = control, P?, N?, NP?)

304 Hydrobiologia (2010) 646:295–309

123

Discussion

This study demonstrated that CRS functional groups

markedly responded to enrichment during periphyton

succession and, particularly, to phosphorus amend-

ment. Isolated and combined P addition promoted

the increase of C–S-strategists and a decrease of

R-strategists. Moreover, under isolated nitrogen

addition (high P limitation) Cyanobacteria R-strate-

gists were favored during early and later successional

stages. Although not directly measured, light proba-

bly had little or no interference since the highest

periphyton growth occurred with P addition (P?

and NP?) when phytoplankton biomass was also

Table 3 Loadings of the abundant species on the first two principal components (PC), functional categories, and taxa codes

Taxa Code PC 1 PC 2 Strategies Size Adherence Growth

class form form

Achnanthidium saprophila (Kobayasi & Mayama)

Round & Bukhtiyarova

Asa 0.343 20.686 R Nano Prostrate Unicellular

Aphanocapsa conferta (West & West) Komarkova-

Legnerova & Cronberg

Acon 0.429 0.845 R Nano Prostrate Colonial

Carteria multifilis (Fresenius) Dill Cmul 0.712 20.496 C–S Nano Mobile Flagellate

Characium rostratum Reinhardt Cros 0.903 20.041 C–S Nano Stalked Unicellular

Chlamydomonas epibiotica G.M. Smith Cepi 0.424 20.737 C–S Nano Mobile Flagellate

Chlamydomonas planctogloea Skuja Cpla 0.722 20.409 C–S Nano Mobile Flagellate

Chlamydomonas sagittula Skuja Csag 0.863 20.158 C–S Nano Mobile Flagellate

Chlamydomonas sordida Ettl Csor 0.713 20.423 C–S Nano Mobile Flagellate

Chloromonas pumilio Ettl Cpum -0.369 0.500 C–S Nano Mobile Flagellate

Chromulina elegans Doflein Celeg 0.027 0.742 R Nano Mobile Flagellate

Chroococcus minor (Kutzing) Nageli Cmino 0.432 0.859 R Nano Prostrate Colonial

Cryptomonas erosa Ehrenberg Cero 0.017 -0.131 R Nano Mobile Flagellate

Cyanosarcina sp. Cyan -0.063 0.753 R Pico Prostrate Colonial

Eunotia bilunaris (Ehrenberg) Souza Ebi 0.748 0.127 R Micro Prostrate Unicellular

Kirchneriella pinguis Hindak Kpin 0.863 -0.225 C–S Nano Prostrate Colonial

Lemmermaniella pallida (Lemmermann) Geitler Lpal -0.086 0.813 R Nano Prostrate Colonial

Leptolyngbya angustissima (West & West)

Anagnostidis & Komarek

Lang 0.799 -0.093 C–S Nano Entangled Filamentous

Mallomonas actinoloma Asmund & Takahashi Mact 0.553 0.769 R Nano Mobile Flagellate

Monoraphidium arcuatum (Korsikov) Hindak Marc 0.871 -0.063 C–S Micro Prostrate Unicellular

Monoraphidium contortum (Thuret) Komarkova-Legnerova Mcon 0.707 0.021 C–S Micro Prostrate Unicellular

Monoraphidium minutum (Nageli) Komarkova-Legnerova Mmin 0.806 0.273 C–S Nano Prostrate Unicellular

Monoraphidium pseudobraunii (Belcher & Swale)

Heyning

Mpseu 0.786 0.091 C–S Micro Prostrate Unicellular

Nephrodiella semilunaris Pascher Nsem 0.005 0.368 S Nano Prostrate Unicellular

Nitzschia palea (Kutzing) W. Smith var. palea Npal 0.911 -0.145 R Micro Mobile Unicellular

Ochromonas danica Pringsheim Odan 0.426 0.705 R Nano Mobile Flagellate

Pseudanabaena galeata Bocher Pgal 0.758 0.164 C–S Nano Entangled Filamentous

Rhabdoderma sancti-pauli Azevedo et al. Rsan -0.242 -0.152 R Nano Prostrate Colonial

Scenedesmus ecornis (Ehrenberg) Chodat Seco 0.926 0.069 C–S Nano Prostrate Colonial

Scenedesmus linearis Komarek 4 Slin 0.749 -0.183 C–S Nano Prostrate Colonial

Scenedesmus spinosus Chodat var. spinosus Sspi 0.921 0.013 C–S Nano Prostrate Colonial

Synechoccocus nidulans (Pringsheim) Komarek in Bourrelly Snid 0.225 0.902 R Pico Prostrate Unicellular

Tetrarcus ilsteri Skuja Tilst -0.188 0.666 R Pico Prostrate Colonial

Bold numbers: higher Pearson correlations with PC

Hydrobiologia (2010) 646:295–309 305

123

the highest. Accordingly, in the present reservoir,

Ferragut & Bicudo (2009) highlighted the phosphorus

enrichment as the main driver of periphyton species

structure on NDS (nutrient diffusing substrate), but

not to P addition levels increase.

Enrichment also influenced other periphyton attri-

butes such as growth forms, algal size classes, and

adherence forms. Considering growth forms, while

flagellates dominated in the control, enrichment

favored other forms, mainly unicellular. Growth

forms are functionally interpreted as survival strate-

gies in unstable environments because distribution of

forms arises from numerous species’ interactions and

selective environmental properties, with nutrient

availability as one of the selective factors (Margalef,

1978). Mobility of periphytic flagellates has an

adaptive survival advantage, allowing access to

different resource sources (Happey-Wood, 1988;

McCormick, 1996). Filamentous forms possess mor-

phologic advantage as for the transport of nutri-

ents from surroundings, particularly phosphorus

(Cattaneo, 1987; Horner et al., 1990). Although

enrichment reduced flagellates contribution and, in

general, decreased diversity of growth forms, changes

were not characterized by the specific nutritional

amendment.

Changes of phytoplankton size classes can be

indicative of environmental disturbances (Sprules &

Munawar, 1986; Reynolds, 1997). In periphyton,

some studies associated algal size distribution

changes to environmental trophy (Cattaneo, 1987;

Cattaneo, 1992). As for nanoplankton (Watson &

Kalff, 1981), decrease of nanoperiphyton was

reported in enriched systems, and increase of periph-

yton algal size proportion was associated to higher

nutrient availability (Cattaneo, 1987; Cattaneo et al.,

1997). Yet, decrease of picoplankton due to phos-

phorus enrichment was also reported (Schallenberg &

Burns, 2001). Similarly, present results showed a

nanoperiphytic decrease trend with enrichment. Iso-

lated and combined P addition (P?, NP?) favored

microperiphyton, while under severe P limitation

(N?) picoperiphyton dominated. Several studies have

shown the advantage of small species over large ones

C3C6

C9C12

C15

C20 C25C31

N3

N6

N9

N12

N15

N20N25

N31

P3

P6

P9 P12

P15

P20

P25P31

NP3 NP6

NP9NP12

NP15

NP20NP25

NP31

Acon

Asa

Celeg

Cepi

Cmino

Cmul

Cpla

Cpum

CrosCsag

Csor

Cyan

Ebi

KpinLang

Lpal

Mact

Marc

Mcon

Mmin

Mps eu

Npal

Nsem

Odan

Pgal

SecoSlin

Snid

Sspi

Tilst

-10

-6

100

-2

2

6

ControlN+P+NP+

C-S strategies

Axis 1 (41.8%)

Axis 2 (26.9%)

R-strategies

Fig. 6 PCA biplot of periphytic algae density and scores for

the four treatments during the experimental period (C control,

N N? treatment, P P? treatment, NP NP? treatment). Scores

abbreviations: first letters refer to treatment and the numbers to

experiment day. For correlation of species with principal

components and respective codes see Table 3

306 Hydrobiologia (2010) 646:295–309

123

under low nutrient availability (Cattaneo et al., 1997;

Irwin et al., 2006; Passy, 2007). Nevertheless,

Sommer & Kilham (1985) and Perez-Martinez &

Cruz-Pizarro (1993) pointed out that algal size is

more reliably associated to environmental changes

when the differences in size are several orders of

magnitude. Indeed, in this study, changes of peri-

phytic algal size classes were not characterized by the

enrichment type, most probably due to prevalence of

small forms (nanoperiphytic and picoperiphyton) in

treatments.

In relation to adherence forms, periphytic algae are

strategically positioned within the matrix to effi-

ciently use resources from the substratum and/or the

water column (Burkholder, 1996). In this study,

dominance of loosely attached algae (mobile) was

observed in the control, whereas in the enriched

treatments there was an increase of firmly attached

algae, mainly prostrate and entangled forms. Thus,

adherence forms were mainly affected by the nutrient

availability increase, and not by the kind of

amendment.

Considering the analyzed attributes, periphyton

CRS adaptive strategies were more sensitive to the

amendments. According to Biggs et al. (1998),

periphyton functional strategies change towards

climax, with R-strategists as pioneers and S-, C–S- or

C-strategists occurring in advanced successional

stages, depending on disturbance and resource sup-

ply. In a large river of the temperate region, fast

growing species (R-strategists) were reported in the

first week of colonization, being outnumbered by

C- and C–S-strategists in the second week of

succession (Acs et al., 2000). Functionally, R-strat-

egists are small pioneering species, with superior

dispersal ability, firm adherence to the substratum,

and are very competitive in conditions of variable

enrichment (McCormick, 1996; Biggs et al., 1998;

Carrick & Steinman, 2001). The presence of C- and

C–S-strategists depends on the resources availability;

these groups include highly competitive species in

eutrophic and mesotrophic condition, respectively

(McCormick, 1996; Biggs et al., 1998).

At present, C–S-functional group was clearly

associated to high phosphorus availability in P?

and NP? treatments. Based on trophic state index,

these treatments were classified as meso-eutrophic.

Taxa of the C–S-functional group appear most

competitive in a stable environment, with low to

moderate disturbance, where nutrients are in moder-

ate availability and mesotrophic condition prevails

(Biggs et al., 1998; Carrick & Steinman, 2001).

Species that best characterized this functional group

comprised mostly green algae (Scenedesmus ecornis,

Scenedesmus spinosus, Chlamydomonas sagittula,

Characium rostratum, Kirchneriella pinguis, and

Monoraphidium arcuatum). R functional group was

mainly associated to phosphorus limitation (N?, C).

This group was described for pioneering species that

are most competitive in a highly unstable environ-

ment, with frequent disturbances, and wide nutrient

demand spectrum (Biggs et al., 1998; Carrick &

Steinman, 2001). Under high phosphorus limitation

(N?), species that characterized this group included

cyanobacteria (Synechococcus nidulans, Chroococ-

cus minor, and Aphanocapsa conferta). S functional

group (tolerant to stress, more competitive in oligo-

trophic and stable environments) was little repre-

sented in the community, and it was expected to

occur in the control (P-limiting condition). Instead, R

functional group was mainly characterized by

Chromulina elegans, most probably due to nutritional

stress condition. C-strategists were the least repre-

sented in the community. This group is characterized

by high competitiveness in stable and eutrophic

conditions (Biggs et al., 1998), disappearing in

moderate levels of enrichment (Carrick & Steinman,

2001). The absence of this group in P? and N?

treatment may be explained by the establishment of

high N and P limitation, respectively. In addition, the

low distribution of C-strategists in the NP? treatment

is probably due to the good nutrients availability,

favoring C–S-strategies, besides trophic condition in

the range of meso-eutrophic condition. Thus,

advanced stages were either characterized by

R-strategies under P limitation (C, N?), or by

C–S-strategies with P amendment (P?, NP?).

In conclusion, our findings show that enrichment

markedly change periphyton adaptive strategies in

this oligotrophic reservoir. However, size class

changes were more sensitive to high phosphorus

limitation, while growth and adherence forms were to

enrichment in general, although not associated to the

amendment kind. Only the CRS strategies were more

predictive of nutrient availability. Therefore, CRS

adaptive strategies of periphyton were first influenced

by higher phosphorus availability (P? and NP?;

mainly C–S functional group), then by nutritional

Hydrobiologia (2010) 646:295–309 307

123

stress (N? : high P-limitation; R functional group)

and, finally, by autogenic processes during succession

(R functional group, initial stages). In addition, these

results were both supported by species density and

biomass, since community was dominated by nano-

and picoperiphyton-size classes.

This contribution to tropical lentic ecosystem

reinforces the use of functional groups approach to

periphyton, as described for rivers in temperate

regions (e.g., Biggs et al., 1998, Acs et al., 2000),

and subtropical lentic system (Carrick & Steinman,

2001), and successfully applied to phytoplankton

community (e.g., Huszar et al., 2000). Studies

addressing its applicability on larger scales should

be stimulated, seeking for a simplified understanding

of periphyton community organization in response to

environmental changes, therefore contributing to

ecosystem management efforts.

Acknowledgments Authors are indebted to FAPESP

(Fundacao de Amparo a Pesquisa do Estado de Sao Paulo)

for a Doctoral Fellowship given to the first author, and to CNPq

(Conselho Nacional de Desenvolvimento Cientıfico e

Tecnologico) for a grant given to DCB (Grant n8 301447/06-3).

References

Acs, E., K. T. Kiss, K. Szabo & J. Makk, 2000. Short-term

colonization sequence of periphyton on glass slides in a

large river (River Danube, near Budapest). Archiv fur

Hydrobiologie 100: 135–156.

Arauzo, M. & A. Cobelas, 1994. Phytoplankton strategies and

time scales in a eutrophic reservoir. Hydrobiologia 291:

1–9.

Bicudo, D. C., 1990. Consideracoes sobre metodologia de

contagem de algas do perifıton. Acta Limnologica

Brasiliensia 3: 459–475.

Bicudo, D. C., M. C. Forti, C. F. Carmo, C. Bourotte, C. E. M.

Bicudo, A. J. Melfi & Y. Lucas, 2002. A atmosfera, as

aguas superficiais e os reservatorios no PEFI: caracter-

izacao quımica. In Bicudo, D. C., M. C. Forti, C. E. M.

Bicudo (orgs.), Parque Estadual das Fontes do Ipiranga

(PEFI): unidade de conservacao que resiste a urbanizacao

de Sao Paulo. Ed. Secretaria do Meio Ambiente do Estado

de Sao Paulo, Sao Paulo: 161–212.

Bicudo, D. C., B. M. Fonseca, C. E. M. Bicudo, L. M. Bini &

T. A. Jesus, 2006. Remocao de Eichhornia crassipes em

um reservatorio tropical raso e suas implicacoes na clas-

sificacao trofica do sistema: estudo de longa duracao no

Lago das Garcas, Sao Paulo, Brasil. In Tundisi, J. G., T.

Matsumura-Tundisi & C. V. Sidagis-Galli (eds), Eutrof-

izacao na America do Sul: causas, consequencias e

tecnologias de gerenciamento e controle. Instituto Inter-

nacional de Ecologia, Sao Carlos: 413–438.

Biggs, B. J. F., R. J. Stevenson & R. L. Lowe, 1998. A habitat

matrix conceptual modes for stream periphyton. Archiv

fur Hydrobiologie 143: 21–56.

Burkholder, J. M., 1996. Interaction of benthic algae with their

substrata. In Stevenson, R. J., M. L. Bothwell & R. L.

Lowe (eds), Algal Ecology: Freshwater Benthic Ecosys-

tems. Academic Press, San Diego: 253–298.

Burliga, A. L. M., A. Schwarzbold, E. A. Lobo & V. D. Pillar,

2004. Functional types in epilithon algae communities of

the Maquine River, Rio Grande do Sul, Brazil. Acta

Limnologica Brasiliensia 16: 369–380.

Carlson, R. E., 1977. A trophic state index for lakes. Limnology& Oceanography 22: 361–369.

Carrick, H. J. & A. D. Steinman, 2001. Variation in periphyton

biomass and species composition in Lake Ockeechobee,

Florida (USA): distribution of algal guilds along envi-

ronmental gradients. Archiv fur Hydrobiologie 152:

411–438.

Cattaneo, A., 1987. Size distribution in periphyton. Canadian

Journal of Fisheries and Aquatic Sciences 44: 2025–2028.

Cattaneo, A., 1992. The anthropogenically stressed periphyton

of lake Orta, Italy. Hydrobiologia 206: 1–10.

Cattaneo, A., G. Methot, B. Pinel-Alloul & T. Niyonsenga,

1995. Epiphyte size and taxonomy as biological, indica-

tors of ecological and toxicological factors in Lake Saint-

Francois (Quebec). Environmental Pollution 87: 357–372.

Cattaneo, A., T. Kerimian, M. Roberge & J. Marty, 1997.

Periphyton distribution and abundance on substrata of

different of stream trophy. Hydrobiologia 354: 101–110.

Ferragut, C. & D. C. Bicudo, 2009. Efeito de diferentes nıveis

de enriquecimento por fosforo sobre a estrutura da com-

unidade perifıtica em represa oligotrofica tropical (Sao

Paulo, Brasil). Revista Brasileira de Botanica 32: 569–

583.

Fonseca, C. R. & G. Ganade, 2001. Species functional redun-

dancy, random extinctions and the stability of ecosystems.

Journal of Ecology 89: 118–125.

Golterman, H. L. & R. S. Clymo, 1971. Methods for Chemical

Analysis of Freshwaters. Blackwell Scientific Publica-

tions, Oxford.

Golterman, H. L., R. S. Clymo & M. A. M. Ohmstad, 1978.

Methods for Physical and Chemical Analysis of Fresh-

waters. Blackwell Scientific Publications, Oxford.

Graham, L. E. & L. W. Wilcox, 2000. Algae. Prentice Hall,

New Jersey.

Grime, J. P., 1977. Evidence for the existence of three primary

strategies in plants and its relevance to ecological and

evolutionary theory. American Naturalist 982: 1169–

1194.

Happey-Wood, V. M., 1988. Ecology of freshwater planktonic

green algae. In Sandgreen, C. D. (ed.), Growth and

reproductive strategies of freshwater phytoplankton.

Cambridge University Press, Cambridge: 175–226.

Hasle, G. R. & G. A. Fryxell, 1970. Diatoms: cleaning and

mouthing for light and electron microscopy. Transactions

of the American Microscopical Society 89: 469–474.

Hillebrand, H., D. Durseken, D. Kirschiel, U. Pollingher &

T. Zohary, 1999. Biovolume calculation for pelagic and

benthic microalgae. Journal of Phycology 35: 403–424.

Horner, R. R., E. B. Welch, M. R. Seeley & J. M. Jacob, 1990.

Responses of periphyton changes in current velocity,

308 Hydrobiologia (2010) 646:295–309

123

suspended sediment and concentration phosphorus.

Freshwater Biology 24: 215–232.

Huston, M., 1979. A general hypothesis of species diversity.

American Naturalist 113: 81–101.

Huszar, V. L. M., P. Domingos & C. L. Sant’Anna, 2000.

Cyanoprocaryote assemblages in eight productive tropical

brasilian waters. Hydrobiologia 424: 67–77.

Irwin, A. J., Z. V. Finkel, O. M. E. Schofield & P. G. Falkowski,

2006. Scaling-up from nutrient physiology to the size

structure of phytoplankton communities. Journal of Plankton

Research 28: 459–471.

Kamenir, Y., Z. Dubinsky & T. Zohary, 2004. Phytoplankton

size structure stability in a meso-eutrophic subtropical

lake. Hydrobiologia 520: 89–104.

Kilham, P. & R. E. Hecky, 1988. Comparative ecology of

marine and freshwater phytoplankton. Limnology &

Oceanography 33: 776–795.

Lund, J. W. G., C. Kipling & E. D. Le Cren, 1958. The inverted

microscope method of estimating algal numbers and sta-

tistical basis of estimation by counting. Hydrobiologia 11:

143–170.

Mackereth, F. J. H., J. Heron & J. F. Talling, 1978. Water

analysis: some revised methods for limnologists. Titus

Wilson & Son Ltd, Kendall.

Margalef, R., 1978. Life-forms of phytoplankton as survival

alternatives in an unstable environment. Oceanologica

Acta 1: 493–509.

McArthur, R. H. & E. O. Wilson, 1967. The Theory of Island

Biogeography. Princeton University Press, Princeton.

McCormick, P. V., 1996. Resource competition and species

coexistence in freshwater benthic algal assemblages. In

Stevenson, R. J., M. L. Bothwell & R. L. Lowe (eds),

Algal Ecology: Freshwater Benthic Ecosystems. Aca-

demic Press, San Diego: 229–252.

McCune, B. & M. J. Mefford, 1999. PC-ORD for Windows.

Multivariate Analysis of Ecological Data, Version 4.10.

MjM Software Design, Oregon.

McIntire, S., S. Diaz, S. Lavorel & W. Cramer, 1999. Plant

functional types and disturbance dynamics response in

herbaceous vegetation. Journal of Vegetation Science 10:

604–607.

Passy, S. I., 2007. Differential cell size optimization strategies

produce distinct diatom richness–body size relationships

in stream benthos and plankton. Journal of Ecology 95:

745–754.

Perez-Martinez, C. & L. Cruz-Pizarro, 1993. Changes in the

phytoplankton structure and biomass after experimental

fertilization and zooplankton manipulation in a mesotro-

phic reservoir. Internationale Vereinigung fur Theoresti-

sche und Angewandte Limnologie 25: 1232–1235.

Pianka, E. R., 1970. On r and k-selection. American Naturalist

104: 592–597.

Pringle, C. M., 1990. Nutrient spatial heterogeneity: effects on

community structure, physiognomy, and diversity of

stream algae. Ecology 71: 905–920.

Redfield, A. C., 1958. The biological control of chemical

factors in the environment. American Scientist 46: 205–

221.

Reynolds, C. S., 1984. The Ecology of Freshwater Phyto-

plankton. Cambridge University Press, Cambridge.

Reynolds, C. S., 1988. Functional morphology and the adaptive

strategies of freshwater phytoplankton. In Sandgreen, C.

D. (ed.), Growth and reproductive strategies of freshwater

phytoplankton. Cambridge University Press, Cambridge:

388–433.

Reynolds, C. S., 1997. Excellence in Ecology – Vegetation

Processes in the Pelagic: A Model for Ecosystem Theory.

Ecology Institute, Germany.

Reynolds, C. S., V. Huszar, C. Kruk, L. Naselli-Flores &

S. Melo, 2002. Towards a functional classification of the

freshwater phytoplankton. Journal of Plankton Research

24: 417–428.

Schallenberg, M. & C. W. Burns, 2001. Tests of autotrophic

picoplankton as early indicators of nutrient enrichment in

an ultra-oligotrophic lake. Freshwater Biology 46: 27–37.

Sladeckova, A. & V. Sladecek, 1964. Periphyton as indicator

of the reservoir water quality. I – True-periphyton.

Technology of water 7: 507–561.

Sladeckova, A. & V. Sladecek, 1977. Periphyton as indicator

of the reservoir water quality. II – Pseudo-periphyton.

Archiv fur Hydrobiologie 9: 176-191.

Solorzano, L., 1969. Determination of ammonia in natural

waters by the phenolhypochlorite method. Limnology &

Oceanography 14: 799–801.

Sommer, U. & S. S. Kilham, 1985. Phytoplankton natural

community competition experiments: a reinterpretation.

Limnology & Oceanography 30: 335–346.

Sprules, W. G. & M. Munawar, 1986. Plankton size spectra in

relation to ecosystem productivity, size and perturbation.

Canadian Journal of Fisheries and Aquatic Sciences 43:

1789–1794.

Steneck, R. S. & M. N. Dethier, 1994. A functional group

approach to the structure of algal dominated communities.

Oikos 69: 476–498.

Strickland, J. D. & T. R. Parsons, 1965. A manual of sea water

analysis. Bulletin of the Fisheries Research Board of

Canada 125: 1–185.

Sun, J. & D. Liu, 2003. Geometric models for calculating cell

biovolume and surface area for phytoplankton. Journal of

Plankton Research 25: 1331–1346.

Utermohl, H., 1958. Zur Vervolkomnung der quantitative

phytoplankton: methodik. Mitteilungen Internationale

Vereinigung fur Theoretische und Angewandte Limnolo-

gie 9: 1–38.

Valderrama, G. C., 1981. The simultaneous analysis of total

nitrogen and total phosphorus in natural waters. Marine

Chemical 10: 109–122.

Watson, S. & J. Kalff, 1981. Relationship between nano-

plankton and lake trophic status. Canadian Journal of

Fisheries and Aquatic Sciences 38: 960–967.

Hydrobiologia (2010) 646:295–309 309

123