13 Spatial variation of fish communities among terra firme forest streams of the Colombian Amazonia

Spatial variation of fish communities among terra firme forest streams of the Colombian Amazonia

Thesis Report MSc. in Tropical Ecology (60 ECTS) Universiteit van Amsterdam 14-08-2006

Supervisors:

Fernando Arbelåez UvA student number: 0312924 farbelae@gmail.com Calle 95 # 16 – 23 A.601 +57 1 6107335

Dr. Joost F. Duivenvoorden Institute for Biodiversity and Ecosystem Dynamics Faculty of Science Universiteit van Amsterdam

Javier A. Maldonado-Ocampo Inventories program Ichthyology collection coordinator Instituto Alexander von Humboldt

Arbeláez, F., Duivenvoorden, J.F. and J.A.Maldonado-Ocampo. 2006. Spatial variation of fish communities among terra firme forest streams of the Colombian Amazonia

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––ACKNOWLEDGEMENTS–––––––––––––––––––––––––––––––––––––––––––––––––––– This work was possible thanks to the financial and logistical support of the following institutions: Tropenbos-Colombia, Universiteit van Amsterdam – IBED, WWF-Education for Nature- Russell E. Train Fellowship programme, Idea Wild, Instituto de Investigaciones Alexander von Humboldt, El Zafire Research Station, Parque Natural Nacional Amacayacu and Fundación Biodiversa Colombia.

I wish to thank my advisors, Joost Duivenvoorden and Javier Maldonado, for their constant help and support during every phase of this project. Many thanks to María Cristina Peñuela, for her great interest and her logistical support, to Iván Arce for his contribution to this project, to Juan David Sánchez for his numerous advises in the field, to Juan David Bogotá for his help in Villa de Leyva and to Dr. Donald Taphorn, for his help with the identification of Characiformes. To my field guides Lizardo, Navilio, Richard, Ángel, Julio César, Leonel, Juan Carlos, Hernando, José, Javier and Gerardo. For their hospitality, I am very grateful with the staff from El Zafire and from Amacayacu National Park, to the communities of Santa Sofía, Mocagua and San Martín, and with Isabella, Diana, Aquiles and Ana María. …A la Tita Fanny

Arbeláez, F., Duivenvoorden, J.F. and J.A.Maldonado-Ocampo. 2006. Spatial variation of fish communities among terra firme forest streams of the Colombian Amazonia

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––INTRODUCTION–––––––––––––––––

Cordillera and the Guyana Shield. In this

In Amazonian terra firme (uplands that are

regard, two main systems have been

not seasonally flooded), soils tend to be

recognized (Duivenvoorden and Lips 1993,

heavily leached and nutrient poor. Terra

Hoorn 1994b, 1994a, Duivenvoorden and

firme

Lips 1995). Shield-origin systems have

forest

streams

(igarapés)

are

characteristically acidic, due to the presence

received

of humic and fulvic acids, and poor in

weathered soils, and are characterized by

nutrients and dissolved solids. As a result of

very low soil elemental reserves. Andean-

the lack of nutrients and the low light

origin upland systems are developed in

penetration due to the forest canopy, the

parent materials derived from relatively

primary productivity and the presence of

young

aquatic plants in these environments is

resulting in soils comparatively richer in

almost inexistent (Lowe-McConnell 1987,

nutrients (though still poor for agricultural

Walker 1995, Mendonça et al. 2005).

production due to intensive leaching). Forest

However, they receive abundant and varied

plant composition (Duivenvoorden and Lips

contributions

the

1995), as well as terrain morphology (PAT

leafs,

1997) clearly differs between these two

flowers, fruits and litter). These allow the

systems. Satellite imagery and surveys along

development of well-structured and very

the border of Colombia and Peru suggest

complex fish communities (Knöppel 1970,

that these two landscape units coincide in

Lowe-McConnell 1987, Goulding et al.

the southern part of the so-called Trapecio

1988). In a single small stream, more that

amazónico (PAT 1997), the Andes-origin

one hundred fish species can often be

soils corresponding to the Pebas formation,

collected, for what these systems might be

and the Shield-origin soils to the Terciario

among the freshwater environments with the

Superior Amazónico formation. As proposed

highest number of fish species per area in

in Hoorn (1994a), the latter formation will

the world (Arbeláez et al. 2004).

be here referred, informally, as Mariñame

A principal source for heterogeneity in

Sand

Amazonian upland soils is related to the

chronostratigraphic

Tertiary

confusion.

surrounding

and

proceeding forest

from

(arthropods,

Pleistocene

environmental

history and the influence of the Andes

sediments

and

Unit,

less

from

ancient

weathered

because name

its

and

sediments,

original generates

Arbeláez, F., Duivenvoorden, J.F. and J.A.Maldonado-Ocampo. 2006. Spatial variation of fish communities among terra firme forest streams of the Colombian Amazonia

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Landscape ecology studies improve the

the patterns that influence the distribution of

understanding of landscape dynamics and

communities in a regional scale.

factors

resources

This study addressed two main hypotheses:

(Schlosser 1991). Assessing the patterns of

(1) The characteristics of soils and waters

diversity allows not only to have a deeper

are significantly different between Pebas

understanding of the factors that govern the

and

species distribution and the maintenance of

Mariñame soils are significantly poorer than

diversity in the landscape, but is also an

Pebas, and thus, that they differ in origin (2)

important

Fish

that

affect

fishery

parameter

in

conservation

Mariñame,

(composition,

2003). Partitioning of diversity components,

biomass)

following

streams

additive

model,

is

an

suggest

communities

planning of protected areas (Crist et al. the

which

richness,

differ from

characteristics abundance

significantly Pebas

that

and

and

between Mariñame

important tool to assess these patterns of

landscape units, which is related to their

diversity (Veech et al. 2002, Crist et al.

difference in soil and water properties.

2003). According to the additive partitioning

Unveiling β diversity patterns is of great

model, γ diversity, or the total diversity in a

relevance

region, results of the addition of β (between-

management

habitat) and α (within-habitat) diversity.

National Natural Park, one of the areas of

Further subdivisions in different levels can

study. Furthermore, some of the species

be made to assess the importance of

inhabiting these streams are often used as

different sources and scales of spatial

ornamental fishes. Locating them and

heterogeneity in the total diversity.

assessing their populations are initial steps

Most of the ichthyological studies carried

for evaluating potential for sustainable

out in the Amazon basin have focused on the

fisheries by local inhabitants.

main rivers and their floodplains, as these

This study was presented as Thesis project

yield most of the commercial fisheries.

to acquire the grade of MSc. in Tropical

However, slight scientific attention has been

Ecology at the University of Amsterdam.

drawn

to

terra

firme

forest

streams

(Mendonça et al. 2005), although unique and highly interesting. Very little is known about their composition and ecology, and about

for

aquatic

plans

of

and the

terrestrial Amacayacu

Arbeláez, F., Duivenvoorden, J.F. and J.A.Maldonado-Ocampo. 2006. Spatial variation of fish communities among terra firme forest streams of the Colombian Amazonia

––MATERIALS AND METHODS––––––

Duivenvoorden

Study area

Duivenvoorden 1996, Duivenvoorden and

The

fieldwork

took

Lips

and

between

Lips 1998). As for the Pebas formation, its

November 2005 and March 2006 in the

original materials have been estimated from

Western Amazonia, specifically, in the

the lower Miocene; they have predominantly

southern Trapecio Amazónico, which is

clay and silty/sandy clay textures, with fine

located in the South-end of Colombia, in the

grain sand and higher nutrient reserves;

Amazonas Department, where it borders

these are presumably of Andean origin

Peru along the Amazon River (Fig. 1) .

(Hoorn 1994a, Lips and Duivenvoorden

The area is characterised by a humid, hot

1996, Vonhof et al. 1998). In the study area,

equatorial

southern

Pebas formation is characterised by a

unimodal/bi-seasonal precipitation regime.

relatively undulated and uniform terrain,

The annual precipitation in Leticia, the

while the surface in Mariñame formation is

Department capital, averages 3.400 mm

dissected by deeper valleys (Rudas-Lleras

(between 1973 and 2004), with the rainiest

and Prieto-Cruz 2005).

period from November to May, and the less

Based on geological cartography (Fig. 1),

rainy season between June and October.

two large sampling areas were chosen,

Temperature is relatively moderate and

where both landscape units were present.

constant along the year, averaging 25.7°C,

The first sampling area, further on called

and humidity is high, with a 86% annual

South-eastern, included the forest near the

mean (Rudas-Lleras and Prieto-Cruz 2005,

village

Galvis et al. 2006).

W070°08’1’’) as the Pebas location, and El

amplings were carried out in terra firme

Zafire

forest streams belonging to the Mariñame

W069°53’47’’) as the Mariñame location.

Sand Unit or the Pebas formations. The

The second sampling area is contained in the

original materials of Mariñame correspond

Amacayacu Natural National Park and

to Early to Middle Miocene, composed

included the forest near Mata-matá station

mainly by medium to very coarse quartz

(S03°49’8’’, W070°15’37’’) as the Pebas

sands with low reserves of cations, P and N,

location, and the headwaters of the Purité

and have been suggested to have originated

basin (S03°41’53’’, W070°12’21’’) as the

in the Guyana Shield (Hoorn 1994a, 1994b,

Mariñame location.

climate

place

1995,

5

and

a

of

Santa

biological

Sofia station

(S04°00’37’’, (S04°00’24’’,

Arbeláez, F., Duivenvoorden, J.F. and J.A.Maldonado-Ocampo. 2006. Spatial variation of fish communities among terra firme forest streams of the Colombian Amazonia

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Fig.1.. Location of the study area, large sampling areas, landscape units and sampling locations. Tsp=Pebas formation.

Tsa=Mariñame formation. Maps sources: Google Earth ® and PAT 1997 Zonificación ambiental para el plan modelo ColomboBrasilero (Eje Apaporis-Tabatinga: PAT). IGAC, Bogotá.

Table 1. Sampling design, and name and specific location of the sampled streams.

Formation Large sampling area

South-eastern

Amacayacu Natural National Park

Pebas Santa Sofía SSQ1. Q. Clímaco.

S03°58’58’’, W070°07’38’’ SSQ2. Q. Tucuchira.

S03°59’8’’, W070°06’50’’ Mata-matá MAQ1. Q. Arriera.

S03°48’23’’, W070°15’58’’ MAQ2. Q. Zanguijuela S03°47’53’’, W070°15’58’’

Mariñame El Zafire ZAQ1. Q. Sufragio.

(S04°00’26’’, W069°53’47’’) ZAQ2: Eufra (S03°59’5’’, W069°53’24’’) Purité PUQ1. Q. Paujil S03°41’54’’, W070°12’24’’ PUQ2. Camarón S03°41’38’’, W070°12’27’’

In each sampling location, two terra firme

should spring inside a well-developed forest

streams were chosen on the basis of local

(with a dense canopy cover) which lacked

informants’ knowledge. The most important

signs

criteria for the stream selection were: (1) it

disturbance; (2) the hydric pulse of the main

of

recent

and

severe

human

Arbeláez, F., Duivenvoorden, J.F. and J.A.Maldonado-Ocampo. 2006. Spatial variation of fish communities among terra firme forest streams of the Colombian Amazonia

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rivers should not affect its water levels near

samples from the middle part of the stream

to the sampling site; (3) it should not fall dry

were taken on sampling days 0, 2 and 4. The

in dry spells; and (4) its size should not be

samples were preserved as fresh as possible,

too large (max. width 6m aprox.) to make

in a refrigerator, when available, or kept

the sampling techniques ineffective. A total

inside running water. Furthermore, pH,

of eight streams were sampled in four

conductivity,

locations, belonging to two large sampling

temperature were measured in-field on

areas and to two landscape units (Table 1).

sampling days 0, 2 and 4, using a portable

dissolved

oxygen

and

multiparameter SensionTM156 HACH. The Soil and water sampling

soil and water samples were analysed at the

In each stream, between three and five

IGAC

700cm3 superficial soil samples (A horizon,

Codazzi) soil laboratory in Bogotá. The

0-5 cm depth) were collected in the forest

studied physical-chemical parameters are

surrounding the streams, at 5 to 10m

listed in Table 2. The detailed results of

distance from the streambed and 10 to 15 m

these analyses and general lab methods are

apart from each other. Three 500ml water

described in Appendix 2.

(Instituto

Geográfico

Table 2. Soil and water variables used in the PCA analyses.

Soil variables Granulometry % of sand % of loam % of clay pH Interchangeable acidity (I.A., meq/100g) % A.I. saturation (A.I.S., meq/100g) % Organic carbon (O.C.) Exchange complex (meq/100g) Cationic Exchange Capacity (C.E.C.) Calcium (ln transformed) Magnesium Potassium Sodium Total bases (T.B.) % bases saturation (B.S.) Phosphorous (ppm)

Water variables pH Electric conductivity (E.C., dS/cm) Sodium Adsorption Rate (S.A.R.) Cation content (meq/L) Calcium Magnesium Potassium Sodium Anion content (meq/L) Sulphates* Chlorides* Carbonates* Bicarbonates Dissolved oxygen (D.O mg/l)** Temperature (°C)**

*Variables removed from the PCA for having too many undetected values. **Field measurements.

Agustín

Arbelรกez, F., Duivenvoorden, J.F. and J.A.Maldonado-Ocampo. 2006. Spatial variation of fish communities among terra firme forest streams of the Colombian Amazonia

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Fish assemblages sampling

Data analyses

In each stream, four daily sampling events

Soil and water data

took place. Each sampling day consisted in a

In order to identify distribution patterns and

standard routine from 14:30 to 19:30,

groups

covering afternoon, dusk and night hours,

sampling areas and landscape units regarding

during which three fishing methods were

their

used: one cast net (multifilament, 1.8 m

properties,

radius, 1.5 cm2 mesh) for the five hours, two

Analyses (PCA) were used to visualise these

dip nets (50 cm diameter, 0.5 mm mesh) for

multidimentional data. Non-detected values

two hours (14:30 to 16:30) and one seine net

were changed for 1/10 of the smallest value

(2 m x 3.5 m, 0.5 mm mesh) for three hours

for that variable. Constant variables and

(16:30 to 19:30). The samplings started from

those with high amount of non-detected

a fixed station, alternating each day between

values were removed from the analyses

upstream and downstream one hundred

(Table 2). Averages of the variables for each

meters transects, and attempting to cover

stream were used as inputs for the PCA. For

every microhabitat for fish within the

the water PCA, the variables used as inputs

transect. All captured individuals were fixed

were the data from lab analyses plus the

in formalin (10%). In the Ichthiology

dissolved oxygen and the temperature from

collection lab of the Humboldt Institute in

the field measurements. Field pH and

Villa de Leyva, Colombia, the fish were

conductivity were used as a reference to

preserved in ethanol (70%), identified,

identify and remove outliers from the lab

counted, and finally deposited in the fish

results.

collection of the Institute. The total catch of

All variables were tested for normality using

each species per sampling day was weighted

a Kolmogorov-Smirnov test with Lilliefors

using an electronic balance, after removing

significance correction. When necessary,

the excess of alcohol. The weights were

variables were transformed to achieve

approximated to the nearest integer in grams

normality, following Zar (1996).

and only the measurements higher than 10g

For each main PCA axis (loading >20%), the

were recorded. A uniform weight of 5g was

difference among sampling locations was

assigned to measurements lower than that

tested with a one-way ANOVA, verifying

value.

the normality of the residuals. When this

formed soil

and two

by

streams,

water

locations,

physical-chemical

Principal

Component

Arbeláez, F., Duivenvoorden, J.F. and J.A.Maldonado-Ocampo. 2006. Spatial variation of fish communities among terra firme forest streams of the Colombian Amazonia

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difference was significant, a Tukey’s honest

samplings, the number of species per

significant difference post hoc test was

sampling day was used as the index for

computed between the sampling locations. In

comparing diversity in different scales. The

the same manner, the difference among

difference in species richness, abundance and

landscape units, sampling areas and their

total weight per sampling day was tested

interaction in each main axis was tested

among sampling locations, as well as among

using a two-ways ANOVA. These analyses

landscape units, sampling areas and the

were performed in SPSS 11.0.1 statistical

interaction

software.

samplings from one stream are probably not

Fish assemblages

independent and, therefore, can not be

In order to evaluate representativeness of the

accounted as repetitions, since the catchment

sampling

species

from one day is likely to affect the results of

accumulation curves and richness estimators

the following days. Therefore, one- and two-

were computed for all the sampling days

ways ANOVAs with repeated measures were

using EstimateS (Version 7.5; Colwell 2005)

performed, using the streams as repetitions

with

without

and the four sampling days as four levels of

replacement and shuffling of individuals

variation of the within-streams “sampling”

among samples within species. The mean

factor.

and confidence values of the Chao1 richness

In order to compare the variation of fish

estimator with bias correction was compared

assemblages among sampling days, streams,

to the number of observed species (Sobs

locations, landscape units and sampling

Mao Tau) and their confidence intervals

areas, a Detrended Correspondence Analysis

(95%), as computed by the software. The

(DCA) ordination technique was performed.

abundance- based Chao1 estimator calculates

The species composition for each sampling

estimated richness based on the amount of

day, with rare species down-weighting, was

singletons (species with only one individual)

used as the input for the DCA, using

and

two

CANOCO for windows (Version 4.02)

individuals) in each step of the sample

ecological software. The differences among

accumulation procedure (Colwell 2005).

locations, landscape units, sampling areas

As standardised fishing procedures and

and their interaction in the scores of each

capture effort were applied during all

DCA axis were tested using one- and two-

in

1000

the

whole

area,

randomisations

doubletons

(species

with

between

these.

Consecutive

Arbeláez, F., Duivenvoorden, J.F. and J.A.Maldonado-Ocampo. 2006. Spatial variation of fish communities among terra firme forest streams of the Colombian Amazonia

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ways ANOVAS with repeated measures. The

greater than expected) or if P > 0.975 (when

DCA scores were also used for a hierarchical

the observed value is smaller than the

cluster

nearest

expected value). The software then calculates

neighbour method, measuring the squared

α and β diversity for each level, following

Euclidian distance between sampling days.

the additive model. For each organisation

As the distance between sampling days

level, α diversity is calculated as the mean

shows how fish assemblages vary due to

diversity index of all samples, while β

environmental factors, daily fluctuations and

diversity is calculated as the total diversity (γ

randomness, the minimum difference for

diversity) minus the average α diversity

clustering was determined when at least all

(Veech et al. 2002). The diversity indicators

samples of the same stream were grouped in

used for these analyses were species richness

the same cluster. Clustering analysis and

and the Simpson’s diversity index. The latter

ANOVAs were performed in SPSS.

expresses the probability that two individuals

In order to evaluate the α and β diversities

randomly selected from any sample belong

contribution in different grouping levels,

to different species (Magurran 1988, Crist et

PARTITION ecological software was used.

al. 2003).

The program first assesses the contribution

The diversity contributions were analysed in

percentage of α and β diversities to the γ at

two different highest grouping levels: first,

diversity at different levels, and then

streams

generates expected values of beta diversity

grouped by landscape units (Pebas and

according to a null model, under the

Mariñame) and second, by large sampling

hypothesis that the observed partition of

areas (South-eastern and Amacayacu N.P.

diversity could be produced by random

areas). In both cases, four levels were used,

allocation. The P values generated by the

with the same first three levels: “among

software values are the proportion of null

samples”, “among streams” and “among

values that are greater than the observed

sampling locations”. The fourth level was

values of α and β diversities (Crist et al.

“among landscape units”, for the first

2003). With a two-tailed probability of 0.05,

analysis, and “among large sampling areas”,

the

significantly

for the second. Finally, the samples from

different from the random distribution model

each landscape unit, Pebas and Mariñame,

if P < 0.025 (when the observed value is

were analysed separately and considering

classification

observed

with

diversity

is

the

and

sampling

locations

were

Arbeláez, F., Duivenvoorden, J.F. and J.A.Maldonado-Ocampo. 2006. Spatial variation of fish communities among terra firme forest streams of the Colombian Amazonia

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only the first three levels of organisation, to

sandier and with higher pH, while Pebas

assess possible differences in diversity

soils tended to be loamier, with higher

partitioning between sampling locations.

interchangeable acidity and higher amounts and saturation of bases.

Water analyses

––RESULTS–––––––––––––––––––––––––

Two water samples from El Zafire showed

Soil analyses

unusually high values of conductivity (46.9

The physicochemical soil and water data for

and 55.6 dS/cm), compared to the other

each stream is presented in Appendix 2.

results and to the field measurements

In the soil PCA (Tables 3 and 4), including

(average 12.4, max. 23.8 dS/cm), for what

the 15 physicochemical variables, the first

they were removed from the analyses.

three axes explained 90% of the variance.

Furthermore,

The first PCA axis significantly separated

chlorides and carbonates) were removed for

Pebas and Mariñame geological formations

their high amount of non-detected values.

on the basis of soil fertility and texture.

The water PCA (Tables 5 and 6), which

The second axis, related among others to

included 10 variables, showed that the two

phosphorous content and interchangeable

first components explained 87% of the

acidity,

two

variance. For both main components, the

sampling areas: Amacayacu NNP and South-

effect of geological formations, sampling

eastern. Finally, the third axis separated

areas and their interaction was highly

significantly Santa Sofia and El Zafire

significant. The post-hoc test showed also a

regarding carbon content, CIC and cation

significant difference between the two Pebas

content. All the analysed variables had high

locations (Santa Sofía and Mata-matá) in

loading (>+/- 0.60) in at least one of the

axis 1 and, in axis 2, a separation between El

three principal axes. The PCA plots (Fig. 2)

Zafire and the other sampling locations.

showed a tendency of streams from the same

These differences, as well as the aggregation

location to be grouped together, especially in

of streams from the same sampling location,

axes 1 and 3 (Fig. 2b), as well as the

were evident in the water PCA plot (Fig. 3).

tendency of Mariñame streams to the left and

All the analysed variables had high loading

Pebas ones to the right of axis 1. In sum,

(>+/- 0.75) in at least one of the three

Mariñame soils had the tendency to be

principal axes.

significantly

divided

the

three

variables

(sulphates,

Arbeláez, F., Duivenvoorden, J.F. and J.A.Maldonado-Ocampo. 2006. Spatial variation of fish communities among terra firme forest streams of the Colombian Amazonia

Table 3. Results of the PCA for physicochemical soil variables within streams, showing the loadings of each variable in the three principal axes and the contribution of each axis to the variance. Bold indicates high loading (>+/-0.6) Variables PCA1 PCA2 PCA3 sand 0.09 -0.80 -0.58 loam

0.85

0.47

-0.07

clay

0.56

0.72

-0.12

pH

-0.60

0.34

-0.07

Interchangeable acidity A.I. saturation Organic carbon Cationic Exchange Capacity

0.70 -0.44 -0.03 0.32

0.66 0.82 -0.52 0.48

0.08 -0.18 0.82 0.81

Calcium (ln) Magnesium Potassium Sodium Total bases bases saturation Phosphorous % Variance explained

0.96 0.94 0.30 0.04 0.96 0.81 0.46 43.2

-0.22 -0.28 0.37 -0.45 -0.22 -0.49 -0.73 27.2

-0.04 -0.12 0.84 -0.80 0.05 -0.31 -0.27 19.5

a.

12

Table 4. Results of one- and two ways ANOVAs and post hoc tests for soil PCA scores. Bold indicates a significant difference Two-ways ANOVA PCA1 PCA2 PCA3 F 11.2 0.7 3.2 Landscape unit (N=4) p 0.03 0.45 0.15 F 0.1 0.2 17.4 Sampling Area (N=4) p 0.77 0.71 0.01 F 1.1 0.2 22.7 Interaction (N=2) p 0.35 0.67 0.01 One-way ANOVA F 4.2 6.1 8.7 Sampling locations (N=2) p 0.10 0.06 0.03 Santa Sofia X Groups formed by Mata-Matá X X Turkey’s HSD by El Zafire X X location (p<0.05) Purité X

1.5

1.5

b.

1.0

1.0

Mariñame soils

Location .5 ZAQ2

Pebas soils 0.0

Mariñame soils -.5

ZAQ2

ZAQ1

ZAQ1

0.0 SSQ2

SSQ2

SSQ1

SSQ1

-.5 PUQ2

PUQ2

PUQ1 -1.0 MAQ2

-1.0

-1.5 -1.5

LOCATION

PCA axis 3

PCA axis 2

.5

PUQ1

Pebas soils

MAQ2

MAQ1 -1.5 -1.0

-.5

0.0

PCA axis 1

.5

1.0

1.5

-1.5

MAQ1

-1.0

-.5

0.0

.5

1.0

1.5

PCA axis 1

Fig.2. Scatter plots for PCA results of 15 soil variables. a) Considering axes 1 and 2 and b) considering axes 1 and 3. Locations: ZA=El Zafire, SS=Santa Sofía, PU=Purité, MA-Mata-matá. Q=stream number. A solid line indicates a significant difference among landscape units. A dotted line indicates significant difference among sampling locations.

Arbeláez, F., Duivenvoorden, J.F. and J.A.Maldonado-Ocampo. 2006. Spatial variation of fish communities among terra firme forest streams of the Colombian Amazonia

Table 6. Results of one- and two ways ANOVAs and post hoc tests for soil PCA scores. Bold indicates a significant difference.

Two-ways ANOVA PCA1 PCA2 F 229.8 15.33 Landscape unit (N=4) p 0.00 0.02 F 85.3 86.2 Sampling Area (N=4) p 0.00 0.00 F 15.4 43.7 Interaction (N=2) p 0.02 0.00 One-way ANOVA F 110.2 48.4 Sampling locations (N=2) p 0.00 0.00 Santa Sofia X X Groups formed by Mata-Matá X X Turkey’s HSD by Purité X X location (p<0.05) El Zafire X X

In sum, Pebas waters appeared to have a higher electric conductivity and greater amount

of

nutrients

and

higher

temperatures than the Mariñame waters.

Among the Pebas locations, in Santa Sofia these variables were significantly higher. The difference in axis 2 implies that certain characteristics of El Zafire waters differed from the other locations, such as higher pH, sodium absorption rate and dissolved oxygen, and less calcium content.

2.0

1.5

Location

1.0

PCA axis 2

ZAQ2

.5

Mariñame waters

-.5

-1.0 -1.5 -1.5

0.52

0.84

Electric conductivity

0.98

-0.20

SSQ1

Sodium adsorption rate

0.38

0.72

PUQ2

Calcium

0.75

-0.61

PUQ1

Magnesium

0.88

-0.42

AMQ2

Potassium

0.96

0.05

AMQ1

Sodium

0.91

-0.16

Bicarbonates

0.82

0.37

Dissolved oxygen

-0.02

0.89

Temperature

0.87

0.14

% Variance explained

58.7

28.0

SSQ2

Pebas waters

-1.0

-.5

0.0

.5

1.0

1.5

Table 5. Results of the PCA for physicochemical water variables within streams, showing the loadings of each variable in the two principal axes and the contribution of each axe to the variance.

Bold indicates high loading (>+/-0.6) Variables PCA1 PCA2 pH

ZAQ1

0.0

13

2.0

PCA axis 1

Fig.3. Scatter plots for PCA results of ten water variables for the two main principal axes. Locations: ZA=El Zafire, SS=Santa Sofía, PU=Purité, MA-Mata-matá. Q=stream number. A solid line indicates a significant difference among landscape units. A dotted line indicates significant difference among sampling locations.

Arbelรกez, F., Duivenvoorden, J.F. and J.A.Maldonado-Ocampo. 2006. Spatial variation of fish communities among terra firme forest streams of the Colombian Amazonia

14

Icthyofauna

thus, the observed richness accounted for

A total of 7656 fish individuals belonging to

81% of the estimated species in the whole

120 species, eight orders and 27 families

area.

were

captured

(Table

7).

The

orders

Characiformes and Siluriformes summed 82% of the total species. These orders were also the most abundant, in particular Characiformes, which accounted for 81% of the

captured

individuals.

The

family

Characidae had the highest richness (36%) and

abundance

(76%).

In

richness,

Characidae was followed by Loricariidae and Auchenipteridae,

and

in

abundance,

it

preceded Cichlidae and Loricariidae. The complete

list

of

species

with

their

abundances in each stream is presented in Appendix 1.

The Chao1 richness estimator (Fig. 4) predicted that the number of species among all the samples is 149 species, significantly higher than the observed richness (120 species) with a 95% confidence interval;

Species richness

200 180 160 140 120 100 Sobs (Mao Tau)

Chao 1

Fig.4. Means and 95% confidence intervals of observed and Chao1 predicted richness.

Table 7. Distribution of the total capture by number of species and individuals by orders and families.

Species Individuals ORDERS Characiformes 58 6229 Siluriformes 41 702 Perciformes 8 457 Gymnotiformes 8 248 Cyprinodontiformes 2 17 Synbranchiformes 1 3 Beloniformes 1 2 Lepidosireniformes 1 1 FAMILIES Characidae 43 5845 Loricariidae 11 238 Auchenipteridae 9 164 Cichlidae 7 456 Heptapteridae 7 70 Callichthyidae 6 109 Curimatidae 4 55 Lebiasinidae 3 177 Aspredinidae 3 90 Hypopomidae 3 90 Anostomidae 3 9 Sternopygidae 2 86 Gasteropelecidae 2 71 Gymnotidae 2 25 Trichomycteridae 2 18 Rivulidae 2 17 Erythrinidae 1 64 Rhamphichthyidae 1 47 Pimelodidae 1 9 Acestrorhynchidae 1 4 Chilodontidae 1 4 Cetopsidae 1 3 Synbranchidae 1 3 Belonidae 1 2 Doradidae 1 1 Lepidosirenidae 1 1 Polycentridae 1 1 120 7659 Total

Arbeláez, F., Duivenvoorden, J.F. and J.A.Maldonado-Ocampo. 2006. Spatial variation of fish communities among terra firme forest streams of the Colombian Amazonia

15

Table 8. Results of ANOVAs with repeated samples (factor: sample with four levels) Two-ways ANOVA Landscape unit (N=4) Sampling Area (N=4) Interaction (N=2)

F p F p F p

Richness 122.51 0.00 33.20 0.00 2.47 0.29

Abundance 0.32 0.81 0.62 0.82 0.46 0.54

Weight 16.45 0.02 4.19 0.11 1.98 0.23

F p

52.39 0.00

0.32 0.81

7.54 0.04 X X X X X

One-way ANOVA Sampling locations (N=2) Groups formed by Turkey’s HSD by location (p<0.05)

Santa Sofia Mata-Matá El Zafire Purité

X X X X

When analysing the total capture in the area,

The number of individuals (Table 7) was not

most of the species had low abundances and

significantly different among locations or

total and individual weights while very few

among landscape units, sampling areas and

species showed high abundances and total

their interaction (Table 8).

and individual weights (Fig. 5).

The difference of weight (Table 7), on the

The number of species (Table 8) differed

contrary, was highly significant between

significantly among sampling locations. The

locations and between landscape units (Table

two Pebas locations (Santa Sofia and

8). Santa Sofía showed a significantly higher

Amacayacu) formed a homogenous group

total

with the highest number of species, while the

locations. In total, Pebas samples summed

location with fewest species was Purité.

more than twice the weight of the Mariñame

Among landscape units and sampling areas,

samples.

the Pebas streams have a significantly higher richness

that

the

Mariñame

streams;

likewise, the South-eastern sampling area showed

a

higher

Amacayacu area.

richness

than

the

weight

than

the

two

Mariñame

Arbelรกez, F., Duivenvoorden, J.F. and J.A.Maldonado-Ocampo. 2006. Spatial variation of fish communities among terra firme forest streams of the Colombian Amazonia

a. 1800 1600

Rank 1 2 3 4 5 6 7 8 9 10

Total weight (g)

1400 1200 1000 800 600

Species Bujurquina mariae Bryconops cf inpai Cyphocharax spiluropsis Bryconamericus sp.

Brycon melanopterus Moenkhausia cf comma Hyphessobrycon cf agulha Charax cf. tectifer Astyanax abramis Gymnotus cf carapo

Total Weight (g) 1618 1450 861 854 853 720 698 600 584 544

400 200 0 0

10

20

30

40

50

60

70

80

90

100

110

120

130

b. 2000

Total abundance (individuals)

1800

Rank 1 2 3 4 5 6 7 8 9 10

1600 1400 1200 1000 800 600

Species Bryconamericus sp.

Tyttocharax cf cochui Hyphessobrycon cf agulha Bryconops cf inpai Gephyrocharax sp.

Bujurquina mariae Hemigrammus cf analis Moenkhausia (lepidura-complex) sp.

Charax cf. tectifer Nannostomus marginatus

Total abundance 1746 989 708 499 375 291 288 165 142 115

400 200 0 0

10

20

30

40

50

60

70

80

90

100

110

120

130

c. 180

Average weight per individual (g)

160

Rank

Species

1 2 3 4 5 6 7 8 9 10

Crenicichla sp.

Auchenipteridae sp.

Pristobrycon sp.2 Hypostomus oculeus Brycon melanopterus Megalechis thoracata Leporinus friderici Scorpiodoras heckelii Acestrorhynchus lacustris Semaprochilodus insignis

140 120 100 80 60 40

Average weight per individual (g) 1746 989 708 499 375 291 288 165 142 115

20 0 0

10

20

30

40

50

60

70

80

90

100

110

120

Rank of species

Fig. 5.Distribution of abundances(a), total weight (b) and average individual weight (c) for the total capture.

130

16

Arbeláez, F., Duivenvoorden, J.F. and J.A.Maldonado-Ocampo. 2006. Spatial variation of fish communities among terra firme forest streams of the Colombian Amazonia 2.5

from the same stream were considered, three Pebas landscape unit

2.0

clear aggregations were formed, separating Stream

1.5

DCA axis 2

17

ZAQ2 ZAQ1

1.0

SSQ2 SSQ1

.5 PUQ2

0.0

PUQ1

Mariñame landscape unit

MAQ2

-.5

MAQ1

-.5

0.0

.5

1.0

1.5

2.0

2.5

3.0

Fig.6. Scatter plots for DCA results of fish composition per sample for the two main principal axes. Locations: ZA=El Zafire, SS=Santa Sofía, PU=Purité, MA-Matamatá. Q=stream number. A solid line indicates a

DCA

using

composition

among

sampling days showed that the first two axes account for 66% of the variation (43% and 22%,

respectively).

large cluster, from the Santa Sofia and Amacayacu samples, which formed two independent groups.

The DCA ANOVAs with repeated sampling (Table 9) suggested comparable results as the cluster analysis, although with a somehow lower resolution. For both axes of the DCA,

DCA axis 1

The

all the Mariñame samples, grouped in one

The

graphic

representation of the DCA (Fig. 6) clearly

samples

from

Mariñame

and

Pebas

formations were significantly different, but the effect of sampling areas or their interaction was not significant. Among sampling locations, only axis 1 shows a significant

difference,

which

occured

between Santa Sofía and the two Mariñame locations (El Zafire and Purité).

grouped sample events within each stream, and streams within sampling locations. The cluster analysis showed a very strong aggregation among the Mariñame samples; indeed, some sub-clusters were formed by mixed samples of Purité and El Zafire streams, while some samples from the same stream were segregated in different subclusters. When only clusters that included all samples

Table 9. Results of one- and two- ways ANOVAs with repeated measures and post hoc tests for fish composition DCA scores. Bold indicates a significant difference.

Two-ways ANOVA DCA1 DCA2 F 15.62 8.07 Landscape unit (N=4) p 0.02 0.05 F 3.46 0.613 Sampling Area (N=4) p 0.14 0.478 F 5.95 1.83 Interaction (N=2) p 0.07 0.248 One-way ANOVA F 3.50 8.34 Sampling locations (N=2) p 0.13 0.03 Santa Sofia X Groups formed by Mata-Matá X X Turkey’s HSD by Purité X location (p<0.05) El Zafire X

Arbeláez, F., Duivenvoorden, J.F. and J.A.Maldonado-Ocampo. 2006. Spatial variation of fish communities among terra firme forest streams of the Colombian Amazonia

The

randomisation

test

PARTITION

software suggest that the distribution of α and β diversity can not be explained by random distributions of individuals among samples (P<0.025 or P>0.975 in every case, with 5000 randomisations, Table 10).

When richness was used as the diversity index,

the

results

were

similar

when

grouping locations by landscape units or by large sampling areas (Table 10). Overall, α diversity within streams accounted for 36% of the total γ diversity, while β diversity accounted for 64% (excluding “among samples” diversity). Most of this β diversity corresponded

to

the

higher

level

of

organisation, i.e. among landscape units and among large sampling areas (β4=38.4 and 36.3, respectively). The smallest contribution is given by the “among streams” level (β2=12.9) which is even less than the “among samples” level (β1=15.5).

However, Simpson’s diversity index shows different results for the higher grouping

18

Table 10. Results of the diversity partitioning analysis with two different higher grouping: among landscape units and among large sampling areas.

Richness P Simpson P Total 120 0.910 Level 4: Units α4 81.6 1 0.892 1 (n=2) β4 38.4 0 0.018 0 Level 4: Areas α4 83.7 1 0.905 1 (n=2) 36.3 0 0.005 0 β4 α3 Level 3: Locations 56.1 1 0.881 1 (n=4) 25.5 0 0.011 0 β3 α2 Level 2: Streams 43.2 1 0.861 1 (n=8) β2 12.9 1 0.020 0 Level 1: Samples α1 27.7 1 0.848 1 (n=32) β1 15.5 1 0.013 0

the β4 was much higher that when grouping by landscape units (0.018, 28% of the total β diversity) than by large sampling areas (0.005, 8% of the total β diversity).

The contribution of β diversity for species richness among sampling locations is higher when comparing the two Pebas locations, Santa Sofia and Mata-Matá (β3=33.2), than with the two Mariñame locations, El Zafire and Purité (β3= 17.1; Table 11). However, the same analysis for Simpson index does shows similar results in the two landscape units analyses.

levels. When grouping by landscape units, Table 11. Results of the diversity partitioning analysis from Mariñame Only Pebas Richness P Simpson Total 95 0.8948 α 61.8 1 0.8834 Level 3: Locations 3 (n=2) 33.2 0 0.0114 β3 48.7 1 0.8691 α Level 2: Streams 2 (n=2) β2 13.1 0 0.0143 α 31.7 1 0.8555 Level 1: Samples 1 (n=16) β1 17 1 0.0136

with the data either from Pebas either

P 1 0 1 0 1 0

Only Mariñame Richness P Simpson 67 0.889 49.9 1 0.878 17.1 0 0.012 37.1 1 0.852 12.8 0 0.026 23.4 1 0.839 13.7 1 0.013

P 1 0 1 0 1 0

Arbeláez, F., Duivenvoorden, J.F. and J.A.Maldonado-Ocampo. 2006. Spatial variation of fish communities among terra firme forest streams of the Colombian Amazonia

19

––DISCUSSION––––––––––––––––––––––

microhabitats as possible along transects;

Methodological considerations

fishing during different activity times for

This study confirms the already reported

fish; and alternating sampling transects in

high richness of fish species that inhabits

consecutive days. The daily sampling routine

these

Lowe-

hereby presented proved to be effective and

McConnell 1987, Arbeláez et al. 2004).

highly practical in the field; furthermore, it

However, the number of fish species

allowed

captured in this study was more than twice

taking into account daily variations. This

the reported by other works in terra firme

methodology is therefore recommended for

streams of the Brazilian and Ecuadorian

further similar studies in fish communities of

Amazonia (e.g. Crampton, Knöppel 1970,

Amazonian terra firme forest streams.

Saul 1975, Penczak et al. 1994, Buhrnheim

When doing a fish inventory, using several

and Cox-Fernandes 2003, Mendonça et al.

sampling techniques, as was performed in

2005). The North-western Amazonia has

this work, allows capturing a wider range of

been suggested, in general, to support a

species in the community. However, as

particularly high diversity of plants species

sampling techniques vary in effectiveness

(e.g. Duivenvoorden et al. 2002, Kreft et al.

and specificity, this introduces biases in the

2004, Ter Steege et al. 2004, Wittmann et al.

observed structure of the community and

2006), thus a similar pattern could occur

therefore in diversity indexes based on it

with fish species. However, the higher

(e.g.

richness here found, compared for example

However, as the daily sampling methodology

to other works in Western Amazonian (e.g.

was as standardised as possible for each

in Ecuador) suggest that this is certainly not

stream,

the result of a particularly higher richness of

streams of sampled fish assemblages and

Colombian igarapés. It is more likely to be

richness by capture effort unit: sampling

more the consequence of a more effective

days.

streams

((Knöppel

1970,

comparison

Shannon

it

and

allowed

among

samplings,

Simpson

comparison

indexes).

among

sampling methodology used in this and other works in Colombia ((Prieto 2000, Arbeláez

Ichtyofauna

et al. 2004, Galvis et al. 2006). This

Although the total captured number of

includes:

(non-

species was still significantly lower than the

destructive) fishing arts; covering as many

estimated one by Chao1, it could be

diverse

and

effective

Arbeláez, F., Duivenvoorden, J.F. and J.A.Maldonado-Ocampo. 2006. Spatial variation of fish communities among terra firme forest streams of the Colombian Amazonia

20

considered high enough (>80%) to assume

interactions

an

partitioning, and closely related to the

adequate

representativeness

of

the

among

fish

and

resources

sampling on the area.

environment characteristics (Costa and Le

The distribution of taxa, as much in richness

Bail 1999). Reduction of body- and of

as

most

population- sizes in Amazonian poor water

in

systems are examples of the adaptive

Amazonian streams, where Characiformes is

processes that might occur in fish species,

usually the dominant group, followed by

related to strategies to reduce inter- and

Siluriformes

intra-specific competition, in order to allow

in

abundance,

ichthyological

agrees

studies

and

with

carried

out

Perciformes

(mainly

Cichlidae), while Gymnotiformes are usually

resource

common (e.g. (Goulding et al. 1988,

overlapping (Costa and Le Bail 1999,

Arbeláez et al. 2004, Mendonça et al. 2005,

Arbeláez et al. 2004).

and

habitat

partitioning

and

Galvis et al. 2006).

The distribution of abundances among the

Soils and waters among landscape units

whole community showed a very clear

Duivenvoorden (1995) and Duivenvoorden

pattern of distribution (Fig. 5). Most of the

& Lips (1995, 1998) suggested that upland

fish species inhabiting these streams had

soils from the middle Caquetá area differed

lower abundances (1-20 individuals) while

in their physicochemical characteristics. The

few species had high abundances. This

authors reported clayey soils with high

agrees

exchange capacity, interchangeable acidity

with

Amazonian

the

reports

freshwater

for

different

systems

(e.g.

and soil nutrient reserves of the Pebas

(Goulding et al. 1988, Saint-Paul et al. 2000,

formation

de Oliveira et al. 2003, Arbeláez et al. 2004,

attributed to be of Andean origin. They also

L. 2004) and seems to be more pronounced

reported soils with coarser textures and lower

in poor water than in rich water systems

CEC and IA and low levels of the soil

(Saint-Paul et al. 2000, Silvano et al. 2000).

nutrient reserves of the Mariñame Sand Unit

A similar distribution of species was found

formation and the sandstone plateaus (Ali-

for the total and individual weight. The latter

Ferrasols),

is related to a common phenomenon that

Guyana shield. The analyses carried out in

occurs in the Amazon basin, miniaturaization

this work suggested similar differences

of fish species, as the result of rich biological

among the soils of the Pebas and the

(Ali-Acrisols),

probably

which

originated

they

in

the

Arbeláez, F., Duivenvoorden, J.F. and J.A.Maldonado-Ocampo. 2006. Spatial variation of fish communities among terra firme forest streams of the Colombian Amazonia

Mariñame

formations

in

the

21

southern

formations. Nevertheless, other important

Trapecio Amazónico. The soils of Mariñame

variables in the soil analysis, related to base

appear to be sandier and with lower amount

content and base saturation, with much

of nutrients than the ones of Pebas. This was

higher loading than the pH, suggest that

also evidenced in the water characteristics

there is indeed a difference in the bases

that drain these soils, as the electric

content.

conductivity and the loads of dissolved

A significant difference was found between

nutrients in the water were significantly

Santa Sofia and El Zafire soils in the third

higher in Pebas streams. These results

axis of the soils PCA (Fig. 2). Although

support the hypothesis that Amazonian

there are no clearly defined groups for this

upland soils differ in physicochemical

axis, as there is for the first axis or for the

characteristics, and that it could be related to

axes of the waters PCA, there seems to be a

the origin of their sediments, in this case,

range that goes from the Santa Sofia soils

Pebas formation from richer and younger

with high organic content and CEC, to El

sediments of the Andes, and Mariñame

Zafire soils were these values are very low,

formation from older and poorer sediments

together with a trade-off between sodium and

of the Guyana shield.

potassium. It was also found that the waters

It is common that the poorer Amazonian

seemed to differ in nutrient content between

soils, such as the ones that drain the Rio

the two Pebas locations, being Santa Sofia

Negro basin, have a tendency to be acidic,

streams significantly richer than Mata-matá

which results also in waters with very low

streams. These results suggest that there

pH (Goulding et al. 1988). However, this

might be other processes and trade-offs

was not the case when comparing Mariñame

involved in the regional differentiation of

and Pebas formations. The water pH was not

soils and waters than just the separation

an important variable in the water PCA to

between geological formations. For example,

difference the two landscape units, and the

the higher human intervention of the forest

relation was even inversed in the soil pH,

close to the large village of Santa Sofia,

with Mariñame showing higher pH. In

compared to the other locations, might be

Duivenvoorden & Lips (1998), pH was also

playing an important role.

not an important variable to account for the

It is interesting to notice that the results on

difference in soils between these two

water analyses appeared to be more clearly

Arbeláez, F., Duivenvoorden, J.F. and J.A.Maldonado-Ocampo. 2006. Spatial variation of fish communities among terra firme forest streams of the Colombian Amazonia

22

interpretable (streams from same locations

among poorer and richer upland forests in

close to each other, clear separation between

the middle Caquetá. This works suggest,

landscape units) than the soil results. This

however, that Pebas formation streams

could occur because localised differences in

support higher fish species richness than the

soil composition were perhaps amplified due

Mariñame formation streams (Table 8). As

to the small size and number of soil samples.

the number of individuals captured was not

These localised differences are “averaged” in

significantly different (Fig. 6b), this result is

the stream water that has drained them, for

not likely to be the consequence of

what

physicochemical

undersampling in the latter. Conditions of

characteristics appeared to give a better

extreme acidity and of low conductivity can

image of the general soil characteristics in

directly

the area area.

environments influence their ionic and acid-

the

water

affect

fishes,

since

such

basic regulation (Gonzalez 1996, cited in Fish

community

characteristics

among

Mendoça

2005).

The

extremely

low

conductivity (<6 dS/cm in average) in poorer

landscape units habitat

upland soils may require more specialised

differences have been suggested to influence

species that can tolerate them, which might

the distribution of fish species (Angermeier

be a limiting factor for species richness

and Karr 1982, Henderson and Crampton

(Towsend et al. 2003).

1997, Mendonça et al. 2005). This study also

Carrying capacity

evidenced that differences in soil properties

The fish carrying capacity in aquatic systems

and in water chemistry were reflected in the

has often been related to the load of nutrients

fish

communities

in their waters, for example when comparing

appeared to be very particularly sensitive to

Amazonian white-water and black-water

water chemistry. In this case, the differences

systems, in relation to size (Galvis et al.

in the fish communities accounted for

2006)

species richness, carrying capacity and

Crampton 1997, Saint-Paul et al. 2000). In

composition.

this study, a similar pattern was observed

Species richness

comparing similar systems that differed in

(Duivenvoorden et al. 2005) did not find

concentration of elements in the water: Pebas

significant differences in tree diversity

streams, richer in elements, showed a much

Physicochemical

factors

communities;

fish

and

and

biomass

(Henderson

and

Arbeláez, F., Duivenvoorden, J.F. and J.A.Maldonado-Ocampo. 2006. Spatial variation of fish communities among terra firme forest streams of the Colombian Amazonia

23

higher carrying capacity than Mariñame

more a reflection of ecological preferences of

streams, reflected in the total weight of the

the

catchments (nearly twice as much).

segregation, though further data is required

Fish composition

to assert this statement (further sampling and

The DCA analyses on fish composition

genetic analyses).

showed a strong relation between differences

Duivenvoorden and Lips (1995) reported

in soil and water characteristics and the fish

differences

assemblages.

from

between Ali-Acrisols from Pebas and Ali-

Mariñame, which had similar soil and water

Ferrasols from Mariñame upland soils.

characteristics seemed to have equally

Likewise,

undifferentiated fish communities. Second,

suggest that the general properties of the

the streams from Pebas appeared to be

soils are an important component for fish

segregated in relation to the sampling

species differentiation. As these forest stream

locations, Santa Sofia and Mata-matá, both

ecosystems are completely dependent on the

in water properties and in fish assemblages.

inputs form the surrounding forest, a very

These differences and similarities in fish

strong

composition could already be evidenced

composition and fish assemblages would be

from the field with the resemblance between

expected. To unveil these patterns, forest

the two Mariñame locations, Purité and El

inventories along the streams, together with

Zafire, separated nearly by 50 km. Some

the fish samplings, should be carried out.

species (i.e. Bunocephalus sp., Moenkhausia

The results of the diversity partitioning

tridentata and Otocinclus sp.; see Appendix

analysis

1) were collected in those two locations but

correspondence analysis. Some differences

in neither of the Pebas locations. Even

and similarities of the fish composition were

closely related species, such as Heptaterus

very evident in the DCA and corresponded to

sp.1 and Heptaterus sp.2, were segregated in

soils and water analyses, but were not

the same area between the two landscape

reflected in a different contribution of the β

units, in locations 25 km away from each

diversity; in particular, this occurred with the

other (Santa Sofia and El Zafire). This

difference between large sampling areas and

general distribution pattern might suggest

among the two Pebas locations. The fact that

that the difference in composition could be

the software does not estimates statistical

First,

the

streams

fish

species

in

the

the

than

forest

composition

hereby-presented

correspondence

were

biogeographical

not

as

results

between

clear

forest

as

the

Arbeláez, F., Duivenvoorden, J.F. and J.A.Maldonado-Ocampo. 2006. Spatial variation of fish communities among terra firme forest streams of the Colombian Amazonia

24

significance of the diversities contributions

National Park. Some results of the present

makes them unreliable for comparison.

work reflect that relation:

Furthermore, the two analysed indexes,

1) The identification of a clear fish β

species richness and Simpson index led to

diversity pattern in the region, conforming

different conclusions. Perhaps the approach

two landscape units with different soil and

of getting an idea of the β diversity as the

water characteristics allows wiser planning

difference between γ diversity and the

and management of land and aquatic

average α diversity is too simplistic and does

resources in the Park.

not really reflect the spatial turnover of

2) The results show a significantly lower

species in a regional scale, at least at the

carrying capacity for one of these units, the

temporal and spatial scale used in this study.

Mariñame formation, which might indicate

It is possible that the differentiation of

that it may be less suitable for exploitation,

landscape units is reflected also in other

and particularly sensitive to destructive

characteristics of the fish community, such

fishing methods, such as ichtyocides, which

as trophic levels structure, reproductive

are still commonly used in certain areas

strategies

(Peñuela pers. com.).

and

physiological

behaviour, and

as

well

as

morphological

3) The whole fish community shows a very

adaptations. Further and more specific

high frequency of rare species. Since rare

studies in these areas are required to gain a

species are particularly vulnerable to habitat

deeper understanding on these aspects.

changes, rarity patterns in the biota reflect the degree of integrity of the environment

Importance for conservation

(de Oliveira et al. 2003). For one side, this

Regional and landscape ecology studies are

reinforces the importance of preserving these

of

environmental

environments, and for the other, changes in

management and planning of natural areas

these distribution patterns could be used as

(Groves 2003, Groom et al. 2006), and

indicators of habitat change and human

improve the understanding of land-use

influence at different ecological scales.

disturbances on fishery resources (Schlosser

4)

1991). This is especially important protected

characteristics

areas, such as the Amacayacu Natural

communities could indicate that the might be

high

relevance

for

The

high

sensitivity

observed

in

to these

water fish

very vulnerable to small habitat changes that

Arbeláez, F., Duivenvoorden, J.F. and J.A.Maldonado-Ocampo. 2006. Spatial variation of fish communities among terra firme forest streams of the Colombian Amazonia

could alter those characteristics, such as contamination, deforestation and change of land use, among others.

The results of this study also suggested that other non-identified factors seemed to be involved in the differentiation of the soil and water

characteristics

and

in

the

fish

assemblages. One clear case of this was the separation of between the two locations of Pebas landscape unit: Santa Sofia and Matamatá. More sampling should be carried out in other areas where the two landscape units coincide, in this and other areas of the Amazonia, e.g. Caquetá, and using the hereby-proposed

methodology.

However,

further studies, involving other techniques, such as molecular biology, and other groups of organisms, will help us improve the knowledge of these patterns of regional diversity.

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Arbeláez, F., Duivenvoorden, J.F. and J.A.Maldonado-Ocampo. 2006. Spatial variation of fish communities among terra firme forest streams of the Colombian Amazonia

28

––A P P E N D I X 1 –––––––––––––––––––––––––––––––––––––––––––––––––––––––––––– LIST OF ESPECIES AND ABUNDANCES MA: Mata-Matá; PU: Purité; SS: Santa Sofía; ZA: El Zafire. Q- stream number Order

Family

Species

Beloniformes

Belonidae

Potamorrhaphis guianensis

Characiformes

Acestrorhynchidae Anostomidae

Characidae

MAQ1

MAQ2

Acestrorhynchus lacustris

1

1

Leporinus af friderici

2

PUQ1

PUQ2 SSQ1 SSQ2 ZAQ1 ZAQ2 Total 2

2

1

5

Leporinus agassizi

1

1

Leporinus cf natereri

1

1

2

10

5

Astyanax anterior

2

1

4

1

Astyanax abramis

1

1

3 1

1

Axelrodia stigmatias (cf.)

1

Brycon melanopterus Bryconops inpai

2 1

Characidium cf. pellucidum

1

8

1

3

5

Characidium sp.1

1

Characidium sp.2

8

6

1

10

12

5

Crenuchus spilurus

1

3

2

2

13

5

1

2

16 15

8

10

8

6

1

Hemibrycon sp.

1

7

8

12

7

2 3

3

19

8

3 10

10

8

5

3

3 8

20 5

2

5

Hyphessobrycon cf agulha

7

11

7

8

2

3

12

8

Knodus breviceps

7

7

5

9

14

10

7

7

Melanocharacidium cf nigrum

1

6

4

1

2

1

1

Moenkhausia cf collettii

6

10

Moenkhausia cf dichroura

5

4

8

10

4

5

1

2

Moenkhausia sp.

Moenkhausia sp.2

9

3

2

4 9 22

8

26 1

15 3 3

7

9

3

Odonthocharacidium aphanes (cf.)

19

1

Phenacogaster af pectinatus

6

11

Pristobrycon sp.1

3

1

Pristobrycon sp.2

2

Roeboides myersii 2

66

16

3

Moenkhausia tridentata

Serrasalmus sp.

1

3 9

58 12

2

1

Moenkhausia lepidura-complejo sp.

Moenkhausia oligolepis

8

2

Microschemobrycon cf geisleri

Moenkhausia comma

68

4

5

Hemigrammus sp.

44 6

4

Hemigrammus cf gracilis Hemigrammus levis

3

3

Gymnocorymbus thayeri

38

2

5

Ctenobrycon hauxwellianus

Hemigrammus analis

9

2

Creagrutus cochui

Gephyrocharax sp.

4 11

7

Charax leticiae Charax tectifer

2

3

4 1

1

3

1 6

26 4

1

3

1

1 3

Arbelรกez, F., Duivenvoorden, J.F. and J.A.Maldonado-Ocampo. 2006. Spatial variation of fish communities among terra firme forest streams of the Colombian Amazonia Steindachnerina guentheri

2

2

4

Tetragonopterus argenteus

1

3

4

Triportheus cf angulatus

3

6

9

Triportheus pictus

1

Tyttocharax cochui Chilodontidae

Chilodus punctatus

Curimatidae

Curimatella alburna Cyphocharax pantostictos

7

1

6

5

9

7

Gymnotiformes

1

2

3

2

2

5

5

1

Hoplias malabaricus

9

8

3

3

Gasteropelecidae

Carnegiella strigata

5

2

3

1

Gasteropelecus maculatus

3

8

Nannostomus marginatus

8

8

1

Pyrrhulina laeta

5

Gymnotidae

Copeina guttata

2 3

30 14 1

1

8

5 1

Rivulus sp.2

2

2 11

Gymnotus cf carapo

6

5

Gymnotus javari

5

2

Brachyhypopomus sp.

7

Gymnorhamphichthys rondoni

Sternopygidae

Eigenmannia virescens

7

2 5

Lepidosirenidae

Lepidosiren paradoxa

Perciformes

Cichlidae

Apistogramma sp.1

7

Apistogramma sp.2

1

2

17 4

1 1

3

1

1

5

3 4

1

3

20

2

6

24

1

1

12

1 5

2

8

6

Crenicichla cf.alta

6

2

Crenicichla sp.

1

9

2

3

6

8

6

9

12

11

75

2

3

1

3

1

18 1

1

1 1

Bunocephalus sp.

2

7

Pterobunocephalus sp.

9

Auchenipteridae sp.

1

Tatia intermedia

6

Tatia perugiae

3 12

15

1 7

2

2

2

1

15 2

1

1

Tetranematichthys quadrifilis

Corydoras semiaquilus

13

1

2 1

1 1

5 1

11 27

1

Corydoras elegans

15 1

Tatia sp.X

Corydoras rabauti

1 6

6

Tatia sp.3 Tatia sp.Y

20 3

1 11

1 17

3 9

Tatia sp.2

4 7

7

Biotodoma sp.

Bunocephalus coracoideus

1

1

8

Bujurquina mariae

6

1

1

Apistogramma sp.3

Aspredinidae

29 1

7

1

4

Lepidosireniformes

Monocirrhus polyacanthus

5

4

Sternopygus macrurus

Polycentridae

6

18

4

Steatogenys elegans

Callichthyidae

3

Rivulus sp.

Rhamphichthyidae

Auchenipteridae

1 2

1

Brachyhypopomus sp.2

Siluriformes

64

11

Gymnotus sp. (revisar) Hypopomidae

9

4

Erythrinidae

Rivulidae

10

3

Semaprochilodus insignis

Cyprinodontiformes

1

11

Cyphocharax spiluropsis

Lebiasinidae

29

4 1 5

3

4 10

10

Arbelรกez, F., Duivenvoorden, J.F. and J.A.Maldonado-Ocampo. 2006. Spatial variation of fish communities among terra firme forest streams of the Colombian Amazonia Corydoras sp.

Denticetopsis praecox

1

5

Megalechis thoracata Cetopsidae

Helogenes marmoratus

Doradidae

Scorpiodoras heckelii

Heptapteridae

Heptapterido (revisar)

2

4

5

1

1

1 1

1

1 1

1

Pimelodella cf steindachneri

3

1

2 4

Farlowella oxyrryncha

1

Farlowella platoryncha

1

Hypostomus oculeus

1

3

1

2

5

1

2

4

17

2

8

9

9

10

47

2

1

2

3

1 7

4

7

14 4

4

Otocinclus sp.2 2 1 3

1

1

1

188

201

Vandellia cirrhosa Total

4 4

6

5

15

1

1

2

3

Rineloricaria cf lanceolata

Synbranchus marmoratus

9

2 4

Trichomycteridae sp.

4 4

Loricarido trompudo

Pimelodus sp.

1

1

Otocinclus sp.

Synbranchidae

1

Loricarido trompa redonda

Trichomycteridae

6 4

2

Limatulichthys griseus

Pimelodidae

2

1

Mastiglanis sp.2

Ancistrus sp.

2 2

3

Pimelodella geryi

3 1

1 1

25 1

1

Mastiglanis asopos

Rineloricaria castroi

6

1

Heptapterus sp.2

Synbranchiformes

9 5

1 1

Heptapterus sp.

Loricariidae

5

30

2

7

1

1

3

4 4

1

1 1

117

114

219

3 191

164

153

1347

Arbeláez, F., Duivenvoorden, J.F. and J.A.Maldonado-Ocampo. 2006. Spatial variation of fish communities among terra firme forest streams of the Colombian Amazonia

31

––A P P E N D I X 2 –––––––––––––––––––––––––––––––––––––––––––––––––––––––––––– DETAILED PHYSICOCHEMICAL DATA OF SOILS AND WATERS FROM EACH STREAM Soil physicochemical analyses South eastern area Santa Sofia El zafire SSQ1 n=5 SSQ2 n=5 ZAQ1 n=3 ZAQ2 Mean SD Mean SD Mean SD Mean

n=3 SD

9.6

54.6 21.6 66.1 17.9

62.8

10.4

loam (%) 38.1

6.5

29.9 14.1 20.8 11.3

22.1

6.3

clay (%) 21.3

3.8

15.6

15.1

4.6

pH 3.4 I.A. (meq/100 g) 6.0 A.I.S. (%) 82.2 O.C. (%) 2.3 C.I.C. 13.1 Ca 0.5 Mg 0.5 K 0.2 Na 0.1 T.B. 1.3 B.S. (%) 10.0 P (ppm) 8.6

0.2 1.2 6.6 0.7 2.2 0.3 0.1 0.0 0.0 0.3 4.0 2.2

Granulom etry

Exchange complex (meq/100g)

Granulometry

sand (%) 40.5

Exchange complex (meq/100g)

sand (%) loam (%) clay (%) pH I.A. (meq/100 g) A.I.S. (%) O.C. (%) C.E.C. Ca Mg K Na T.B. B.S. (%) P (ppm)

7.6

13.1

7.2

3.5 0.1 3.7 0.1 3.5 5.7 3.0 3.3 1.3 4.9 91.2 0.6 83.6 6.1 87.6 1.5 0.7 3.2 1.4 3.6 10.3 6.5 15.1 7.2 16.5 0.2 0.1 0.1 0.0 0.1 0.2 0.1 0.2 0.1 0.2 0.1 0.1 0.2 0.1 0.2 0.0 0.0 0.2 0.2 0.1 0.6 0.3 0.6 0.3 0.7 5.8 1.1 4.6 2.6 4.4 6.1 1.7 6.1 6.8 2.7 Amacayacu NNP area Mata-mata Purite AMQ1 n=5 AMQ2 n=5 PUQ1 n=3 PUQ2 S03 Mean SD Mean SD Mean SD Mean 20.9 3.0 30.9 3.1 58.1 3.1 52.4 51.8 3.0 45.8 2.3 25.0 3.1 23.8 27.3 3.2 23.3 1.2 16.9 3.1 23.8 3.7 0.2 3.6 0.2 4.0 0.1 3.7 8.0 0.6 9.0 0.6 3.5 0.3 5.6 87.8 2.8 92.4 1.6 90.1 1.4 93.8 1.7 0.4 2.3 0.7 1.6 0.5 1.7 16.5 1.4 19.9 1.3 11.3 1.9 15.1 0.5 0.1 0.2 0.1 0.1 0.0 0.0 0.4 0.1 0.2 0.1 0.1 0.0 0.1 0.2 0.1 0.3 0.0 0.2 0.0 0.2 0.1 0.0 0.1 0.0 0.1 0.0 0.1 1.1 0.3 0.7 0.2 0.4 0.1 0.4 6.7 1.3 3.7 0.7 3.4 0.4 2.5 3.4 1.9 3.7 1.3 4.1 2.1 0.6

0.1 1.7 1.6 1.6 6.9 0.0 0.1 0.1 0.1 0.2 0.8 0.7

n=3 SD 8.7 4.3 5.2 0.1 0.5 0.4 0.3 3.1 0.0 0.0 0.0 0.0 0.1 0.4 0.0

Arbeláez, F., Duivenvoorden, J.F. and J.A.Maldonado-Ocampo. 2006. Spatial variation of fish communities among terra firme forest streams of the Colombian Amazonia

Soil physicochemical analyses South eastern area Santa Sofía

pH Electric conductivity (E.C., dS/cm) Calcium Magnesium Potassium Sodium Bicarbonates Sodium Adsorption Rate (S.A.R.) Dissolved oxygen (D.O. µS.cm-1)** Temperature (°C)**

El Zafire SSQ1 SSQ2 ZAQ1 ZAQ2 Average SD n Average SD n Average SD n Average SD n 6.655 0.262 2 6.493 0.488 3 6.815 0.007 2 6.875 0.318 2 22.45

3.748 2

0.065 0.035 0.04 0.055 0.215

0.021 0.007 0 0.007 0.021

0.235

0.007 2

5.043

23.8

8.879 3

6.525

4.469 2

5.85

0.026 0.017 0.01 0.021 0.112

3 3 3 3 3

0.001 0 0.015 0.02 0.13

0.028 0.014 0 0.021 0.014

2 2 2 2 2

0.001 0.005 0.01 0.02 0.13

0.303

0.015 3

0.42

0.078 2

0.335

0.021 2

0.251 2

3.955

0.24 2

5.26

0.368 2

5.418

0.032 2

25.725 0.389 2

26.1

2 0.07 2 0.04 2 0.03 2 0.073 2 0.233

0

0.156 2 0 0 0 0 0

2 2 2 2 2

2 25.425 0.247 2 24.425 0.177 2

Amacayacu NNP area Mata-matá

pH Electric conductivity (E.C., dS/cm) Calcium Magnesium Potassium Sodium Bicarbonates Sodium Adsorption Rate (S.A.R.) Dissolved oxygen (D.O. µS.cm-1)** Temperature (°C)**

Purité

MAQ1 MAQ2 PUQ1 PUQ2 Average SD n Average SD n Average SD n Average SD n 5.877 0.129 3 5.693 0.051 3 5.027 0.231 3 5.077 0.136 3 15.333 1.436 3 13.467 0.058 3

6.113

2.792 3

5.343

1.236 3

0.047 0.02 0.023 0.057 0.07

0.006 0 0.01 0.006 0

3 3 3 3 3

0.033 0.013 0.004 0.01 0.05

0.032 0.006 0.001 0.001 0.035

3 3 3 3 3

0.033 0.007 0.005 0.009 0.053

0.021 0.005 0.004 0.001 0.006

0.313

0.05 3

0.32

0.052 3

0.07

0.017 3

0.07

0.026 3

3.998

0.384 2

3.742

0.012 2

4.393

0.118 2

3.657

1.655 2

3 0.03 3 0.027 3 0.02 3 0.053 3 0.053

0 0.006 0 0.006 0.006

3 3 3 3 3

24.725 0.247 2 24.875 0.318 2 24.575 0.106 2 24.525 0.106 2

32

Arbeláez, F., Duivenvoorden, J.F. and J.A.Maldonado-Ocampo. 2006. Spatial variation of fish communities among terra firme forest streams of the Colombian Amazonia

Methods: Soils Granulometry: Bouyoucos pH Interchangeable acidity (I.A., meq/100g): with KCl; % A.I. saturation (A.I.S.) % Organic carbon (O.C.): Walkley - Black; Cationic Interchange Capacity (C.I.C.) and bases: Ammonium acetate 1 normal and neutral meq Calcium/100g x 200 = ppm. meq Magnesium/100g x 120 = ppm. meq Potassium/100g x 391 = ppm meq Sodium/100g x 230 = ppm Percentage (%) = ppm / 10.000 Phosphorous (ppm) : Bray II; Methods: waters pH: Potentiometric Electric conductivity (E.C., dS/cm) Sodium Adsorption Rate (S.A.R.) Calcium, Magnesium (meq/L): Atomic absorption Potassium, Sodium: atomic emission Anion content (meq/L) Sulphates: turbidimetric Chlorides, Carbonates, Bicarbonates: Potentiometric titulation Dissolved oxygen (D.O. µS.cm-1): field measurements Temperature (°C): field measurements

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