NORBERT WALZ
Institute of Freshwater Ecology and Inland Fisheries Berlin
Müggelseedamm 301,D-12567 Berlin, Germany, e-mail: walz@igb-berlin.de
N.N. coauthors
Publication of BRIC- and Outreach Countries in International Journals on Limnology
key words: bibliometry, references, developing countries, Germany, USA
Abstracts
1. Introduction
Progressive pollution, overexploitation (PIERCE, 2006) and the predicted consequences of
climate warming on water (IPCC, 2008) are a dramatic hazard for all aquatic ecosystems in
the world, but in particular for those in many developing countries. As an inevitable medium
for all kind of living processes the quality and quantity of fresh water is profoundly
endangered (WETZEL, 1992). Declines of biodiversity in freshwater are more dramatic than in
most terrestrial ecosystems (Dudgeon, 2006). A large endeavour of investments in the water
sector is necessary in the near future in many countries. All monetary and engineering
investments have to be based on a sound scientific capacity in those countries. Scientific
knowledge is essential to process further investments to the right way. On the other hand,
many developing countries were economically most successful in the last decade. Will these
countries have the capability to meet the immense challenges in this important sector? Did at
least the most prosperous countries among them used their chance in this passed period and
developed the scientific basis for this task?
A group of developing states is especially prominent and these countries show an ever rapid
development of their economy. These belong to the so called BRIC-states (Brazil, Russia,
India, Peoples Republic of China) (ARMIJO, 2007). Sometimes this group of states is taken
together with Mexico and South Africa to the so called group of Outreach States. These are
the most important countries.
2. Methods
Based on the ISI Web of Science® (http://portal.isiknowledge.com/portal.cgi) of Thompson
Corporation all publications of those countries were analysed in 44 limnological journals
(Table 1) which consider all aspects in freshwater. Most of them are devoted singularly for
limnology, however some of them (e.g., Limnology and Oceanography, International Review
of Hydrobiology) include also marine papers but to a less or to a low content. Many other
journals (e.g., Ecology, Oecologia) also include limnological papers but to a low degree and
were, therefore, not considered (see discussion). The language in all studied journals is
English. Most recommendations of MOED (2002) were followed that were applicable to other
countries and to limnology.
The journals of Table 1 were searched for the number of publications between 1999 and 2007.
The research protocol included the publication name (journal name), the address (name of
country) and the publication year. With the field of address empty, for a comparison purpose
all countries were recorded. This provided the amount of the world production in limnology.
In addition the “citation report” led to the number of references. As the number of references
1
is increasing continuously even years after the appearance of a paper this search was done
within two weeks of August 2008. For that reason the number of references are not suited to
show a time trend and the older developed countries will have much more older papers with
accumulated references. The proportion of under- or overcitation can be evaluated by the
citation quotient:
CQ = Country’s references * N all papers/ All references * N Country’s papers,
where CQ = 1 means, that the references for a country equals the mean for all papers.
No differentiation was made between authors and co-authors when they came from different
countries. All these papers were counted for each country.
The journal impact factors (JIF) were taken from the ISI Journal Citation Report®. The mean
weighted impact factor for a country (IF) was computed as the sum of the Journal Impact
Factors times the number of the papers of a country in that journal divided by the total
number of the papers of that country. This was done over all journals and for each year:
IF 
 ( Ni * JIFi)
Ntot
The relative IF of a year was computed in relation to setting the mean Impact Factor of all
countries to 1.00.
The effect of two “treatments”, year and country, was studied with a two-way Analysis of
Variance on the number of papers and on the IF and was calculated with Stateasy®. As there
was only a single value for each year and country, an interaction term was not received. The
error in accumulation of the alpha level made by multiple comparisons was corrected by a
Bonferroni adjustment. The differences between single countries were evaluated by Tuckeytests.
The exponential growth rate of the number of papers over the years was calculated by an
Analysis of Covariance with Stateasy®. Interaction terms were not received. The thresholds
were corrected by a Bonferroni adjustment. The differences between the slopes of the
regressions belonging to single countries were evaluated by Tuckey-tests.
Values of GDP (Gross Domestic Product) and GERD (Gross Expenditure on Research and
Development) were reported for the year 2005 by the UNESCO Institute for Statistcs:
http://www.uis.unesco.org/ev_en.php?ID=2867_201&ID2=DO_TOPIC for 2005. The values
were related to purchasing power parity (PPP US$).
For the recording of the publication intensity, and therefore of the strength of the countries in
different disciplines of limnology, the search was restricted to the following journals,
respectively, see Table 1 for journal numbers:
(1) General Limnology, 16 Journals: Journal No 2, 4, 5, 8, 9, 12, 15, 18, 23, 29, 33, 35,
36, 38, 41, 43.
(2) Applied Limnology, 10 Journals: Journal No 1, 3, 11, 14, 19, 25, 27, 32, 37, 44.
(3) Fish Biology, 8 Journals:, Journal No 7, 16, 20, 21, 22, 24, 28, 45.
(4) Phycology, 6 Journals: Journal No 6, 10, 13, 26, 31, 42.
(5) Microbiology, 1 Journal: Journal No 40.
2
With these journals 86.8% of all papers in the limnological journals of Table 1 were covered.
Only the journals No 30 and 39 were not considered here.
3. Results
3.1. Overview over the time period from 1999 to 2007
Together all countries studied here published in the time period from 1999 to 2007 nearly the
half of the world’s production in limnology (47.4%). However, the distribution among the
states was very diverse.
Within that period the BRIC and Outreach states produced between 415 (South Africa) and
1583 (Peoples Rep. of China) limnological papers (Table 2). A two-way Analysis of Variance
(with countries and years as treatments) revealed a statistically significant difference (P <
0.01) caused by both treatments (Table 3). A Tuckey-test showed that at P < 0.01 PR China
had a higher output than any other of these countries. Brazil’s output was significantly higher
than that of Russia and South Africa.
In comparison to the investigated countries Germany’s publication output was double that of
China, but USA dominated with an amount of papers nearly 10 times as high and published
nearly 30% of the world papers in limnology. Together the 6 BRIC and Outreach states
reached already a proportion of 10.6% of the world’s limnological publications and this was
higher than that of Germany.
The differences between countries were even more diverse when the number of references
was taken into account (Table 2, citation quotient). Only the papers coming from USA and
Germany were cited above average. The BRIC and Outreach states were undercited between
58% and 80% of the mean value.
The BRIC and Outreach states did not publish in low valued journals; the lowest mean impact
factor was 1.07. An Analysis of Variance revealed statistically significant differences on the P
< 0.01 level for the year and on the P < 0.05 level for the country (Table 4). However a
Tuckey test showed only a significant difference between PR China and Brazil (P < 0.01). At
this significance level, the impact factors of all studied BRIC and Outreach states were also
lower than the factors of USA; compared with Germany, the impact factors were only lower
for Brazil, India and Russia.
There was a strong relationship between GERD of a country and its number of papers
published in 2007 (Fig. 1). The overall relationship yielded an r² = 0.98 (P < 0.0001) with y =
-7.98 + 6.48 x, i.e., with a nominal effort of a billion US$ a production of (inter alia) about 6.5
limnological papers was connected. When the USA were not taken into this comparison, r²
became much lower (0.75) and the significance decreased (P = 0.012).The correlations with
GDP were much weaker with r² = 0.824 (P < 0.001) for the correlation with all countries and
r² = 0.386 (not significant) after USA was excluded.
There was also a positive correlation between the number of references and GERD or GDP,
but the relationship was weaker than to the number of papers. Related to GERD r² was 0.961
(P < 0.01) and related to GDP r² was 0.762 (P < 0.05). Without USA these relationships were
not significant.
3.2. Development within the time period from 1999 to 2007
3
This static observation hides the most interesting aspects as there was a high dynamic
development during this period. Starting from a very narrow field with 42 to 71 papers in
1999, BRIC and Outreach states developed very diverse, with multiplying to 284 papers in
2007 for the Peoples Republic of China or even declining to 39 in the case of South Africa
(Table 5a). At the end of this period China could publish 5% of the limnological papers
(Table 5b), and Brazil reached the second place in the list of BRIC and Outreach countries,
but Russia and South Africa fell back below 1%. In comparison as an example of an older
developed country, the publication output of USA grew steadily and in 2007 the share was
more than 30%. Germany revealed a not encouraging development as it’s output first grew
between 1999 and 2004, but then rapidly lost nearly 30 % in three years and declined to a
level in 2007 which was lower than in 1999.
An Analysis of Covariance (Table 6) revealed significantly (P < 0.01) differences of the
exponential growth rates of the number of papers between all countries as for the slopes as for
the intercepts. The Peoples Republic of China showed the highest growth rates in that time
period (Fig. 2). Also Brazil grew considerably. The growth rate of Mexico and India was only
a third of that of China. Russia and USA had the same low rate, but that of Russia was not
significantly different from zero (P > 0.05), as also the rates of South Africa and Germany
were not significant. The differences between single countries to each other were all
significant on the P < 0.01 level (Tuckey-test).
The impact factors showed a significant increase for all studied countries in absolute numbers
(P < 0.01), but also a rise of the mean impact factors of all countries took place (Fig. 3). An
Analysis of Covariance revealed, however, no significant difference between the slopes, but
there was a significant difference between the intercept at the P < 0.01 level (Table 7).
In order to know if an impact factor differed in relation to the mean impact factor of all
countries, these values were set as 1.00. This procedure excluded the over all trend. If the
impact factors of the different countries were related to that value only the relative impact
factors of India and of the PR China increased significantly (P < 0.05). The relative impact
factor of USA decreased at a significance level of P < 0.05. All other countries showed no
significant deviations to 1.00 (P = 0.05) and, therefore, their impact factors joined the overall
trend.
3.3. Publication strength in different disciplines of limnology
For the total world, most papers were published in journals of Applied Limnology (18205)
between 1999 and 2007 and about 30% less papers (13263) in General Limnology. Fish
Ecology, Phycology and Microbiology followed with 4869, 4129 and 933 papers. Together
The BRIC- and Outreach States studied here contributed between 6.2% (Microbiology) and
16.9% (Fish Biology and Ecology).
General Limnology: PR of China and Brazil contributed the most publications, both countries
with increasing tendency (P < 0.05) (Fig. 4). India significantly decreased. Germany had
9.6% and USA 31.1% papers. The trend in both countries was not significant.
Applied Limnology: PR China had the most contributions of the BRIC and Outreach states,
more than to General Limnology. Also the papers to Applied Limnology increased. PR China
was followed by Brazil which also increased as opposed to South Africa, where the
publications in Applied Limnology decreased. USA contributed most (28.0%) with increasing
4
trend. Germany contributed 7.0%, throughout not with a significant trend. However, a
detailed inspection showed that the proportions rose to 2005, and then decreased in 2006 and
2007.
Biology and Ecology of Fish: This was the discipline where the BRIC and Outreach States
published the most papers. Unchallenged, Brazil had the best standing in this discipline and
multiplied especially in 2006 and 2007. Brazil was followed by PR China, Mexico, Russia,
South Africa and India, all of them with increasing numbers, except Russia. Brazil even got
ahead of Germany (6.0%) that showed no increase in that discipline. In contrast, USA, with
30.2%, revealed a steady increase.
Phycology: Again PR China, was the highest, followed by Brazil, both countries with
significant increase. Such an increase could also be documented for India, although its
numbers were low. Germany with 7.1 showed no further increase, in contrast to USA which
already published 33.5% of all publications and could rose their numbers especially in 2006
and 2007.
Microbiology: As only one journal could be analyzed, the numbers generally were low in this
discipline and fluctuated largely for the different countries. For that reason neither for USA
with 29.6% nor for Germany, with 14.8%, significant changes could be shown. Only PR
China, which again had the highest contribution of the BRIC- and Outreach states, and
Mexico revealed significant increases.
In conclusion, from the BRIC- and Outreach states PR China dominated all disciplines, except
Fish Biology and Ecology, where Brazil was strong. From the highly developed states, USA
had the best position with contributions between 29.6% and 33.5% and it was able to expand
in Applied Limnology, Fish Biology and Phycology. Germany’s contribution of articles was
2-5 times lower than USA and it could not increase in any discipline.
4. Discussion
There might be the anticipation that the papers in the studied 45 journals could be elected
arbitrarily. MELO et al. (2006) in a study on Brazilian papers in limnology from 1970 to 2004
restricted to 13 journals. Their survey overlapped between 1999 and 2004 with the present
study. To expand the time for comparison for the years 1978, 1984 and 1990 further Brazilian
publications were evaluated all journals in Table 1. After a normal distribution was not
declined at 1% according to a Kolmogorov-test, a paired t-test did not reveal a difference of
the percentage of papers of the present study with that of MELO et al. (2006) on the P =
0.0001 level (tdf = 8 = 1.153 < 7.071). Both methods reflected also the same ups and downs.
This seems to be a strong argument that the list of journals is secondary. In fact, this follows
the well known pattern in bibliometry, Bradford’ law, which says that a large percentage of
information is already given when only few journals are considered (BRADFORD, 1934).
It could be a good strategy of publication, to publish in the journals of highest awareness, i.e.,
with high impact factors. The impact factors, however, are not necessary the performance of a
country.
There was a strong correlation between journal impact factor and the number of references for
the journals studied, what has to be expected as with the number of references is in the
numerator of the equation to calculate the impact factor. But the exceptions were interesting.
There remains a large scatter and we revealed an r = 0.61 for all journals and all countries (P
5
< 0.0001, n = 45) for the relationship of impact factor 2007 and the number of references in
2007. This result was the same as LEIMU and KORICHEVA (2005) found for ecological journals
(r = 0.62, P = 0.0004, n = 216). Whereas most countries studied here could earn more
references with publications in higher impacted journals (P < 0.05), Russia and South Africa
did not (P > 0.10). On the other hand, the SA’s and Russia’s numbers of references per article
and the proportions of over/under citation were high, also their mean impact factors. This
means that most references of these two countries were got in journals with a middle or lower
impact factor. A graphical analysis could confirm this result.
LEIMU and KORICHEVA (2005) showed that the citation rate of ecological papers depends on
the country of affiliation. Publications by English speaking first co-authors were referenced
more that those whose first language was not English countries. Papers by US-authors
received more citations than did papers by European authors. Another study shows that under
citation does not result from a low quality of the publication (PARIS et. al, 1998)
Scientific output depends to a large part from the money governments spent for science and
development. We saw a direct relationship to GERD, the gross expenditure on research and
development, but there was a large scatter. YE (2007) constructed a formula to predict the
scientific output of countries on the basis of GERD. The percentage what is going into
limnology is not known. But it may be in the same order as the ratio of the publications in
limnology to all publications in science. In 1999 and 2000, 571,676 and 584,982 SCI papers
were published worldwide (UNESCO, 2005). In relation to these numbers the published
papers in the presently studied journals of limnology were only 0.84% and 0.80% in these
years.
Statistical features, as they are recorded by an analysis of Chinas journals in the ISI Journal
Citation Report®, revealed that China’s journals do not differ from international journals.
They showed the same patterns as for western countries in the growth of the number of
articles and of references (LINAG et. al, 2006)
References
ARMIJO, L. E., 2007: The BRICs countries (Brazil, Russia, India, and China) as analytical
category: mirage or insight?- Asian Perspective 31: 7-42.
BRADFORD, S. C., 1934: Sources of information on specific subjects.- Engineering 137: 8586.
DUDGEON, D., A. H. ARTHINGTON, M. O. GESSNER, Z. I. KAWABATA, D. J. KNOWLER, C.
LEVEQUE, R. J. NAIMAN, A. H. PRIEUR-RICHARD, D. SOTO, M. L. J. STIASSNY and C. A.
SULLIVAN, C. A., 2006: Freshwater biodiversity: importance, threats, status and
conservation challenges.- Biological Reviews 81: 163-182
INTERGOVERNMENTAL PANEL ON CLIMATE CHANGE (IPCC) (ed.) 2008: Climate change and
water. http://www.ipcc.ch/pdf/technical-papers/climate-change-water-en.pdf
LEIMU, R. and J. KORICHEVA, 2005: What determines the citation frequency of ecological
papers?- Trends. Ecol. Evol. 20: 28-32.
LIANG, L., F. HAVEMANN, M. HEINZ and R. WAGNER-DÖBLER, 2006: Structural similarities
between science growth dynamics in China and in western countries.- Scientometrics 66:
311-325.
MELO, A. S., L. M. BINI and P. CARVALHO, P. 2006: Brazilian articles in international
journals on limnology.- Scientometrics 67: 187-199.
6
MOED, H. F., 2002: Measuring China's research performance using the Science Citation
Index.- Scientometrics 53: 281-296.
PARIS, G.; G. DE LEO, P. MENOZZI and M. GATTO, M., 1998: Region-based citation bias in
science.- Nature 396: 210.
PEARCE, F. 2006: When the rivers run dry: Water the defining crisis of the twenty first
century.- Eden Projects Books, 368pp.
UNESCO, Institute for Statistics (ed.), 2005: What do bibliometric indicators tell us about
world scientific output?- UIS Bulletin on Science and Technology Statistics, No. 2, Sept.
2005, 1-6.
WETZEL, R. G., 1992: Clean water. A fading resource.- Hydrobiologia 243/244: 21-30.
YE, F. Y., 2007: A quantitative relationship between per capita GDP and scientometric
criteria.- Scientometrics 71: 407-413.
7
Table 1. Studied journals and journal impact factors in 2007.
No
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
Journal
International Journal of Water Resources Development
Journal of Freshwater Ecology
Water and Environment Journal
Annales de Limnologie-International Journal of Limnology
Limnologica
Journal of Aquatic Plant Management
Journal of Applied Ichthyology
Limnology
Vie et Milieu-Life and Environment
Journal of Applied Phycology
Water Resources Management
Amazoniana-Limnologia et Oecologia Regionalis Systemae Fluminis Amazonas
Phycological Research
Acta Hydrochimica et Hydrobiologica, since 2007: Clean – Soil, Air , Water
Aquatic Ecology
Fisheries Management and Ecology
Lake and Reservoir Management
International Review of Hydrobiology
Water Environment Research
Neotropical Ichthyology
Environmental Biology of Fishes
Fisheries Research
Hydrobiologia
Ecology of Freshwater Fish
Water Science and Technology
Phycologia
Agricultural Water Management
Journal of Fish Biology
Archiv für Hydrobiologie/Fundamental and Applied Limnology
Aquatic Geochemistry
Aquatic Botany
River Research and Applications
Aquatic Sciences
Advances in Water Resources
Journal of Plankton Research
Canadian Journal of Fisheries and Aquatic Sciences
Water Resources Research
Journal of the North American Benthological Society
Journal of Paleolimnology
Aquatic Microbial Ecology
Freshwater Biology
Journal of Phycology
Limnology and Oceanography
Water Research
Fish and Fisheries
Journal
Impact
Factor
0.444
0.452
0.461
0.482
0.593
0.659
0.663
0.712
0.750
0.788
0.790
0.800
0.836
0.888
0.925
0.968
1.041
1.064
1.118
1.133
1.137
1.196
1.201
1.206
1.240
1.358
1.388
1.404
1.409
1.412
1.497
1.551
1.646
1.817
1.897
2.058
2.154
2.217
2.287
2.385
2.650
2.820
3.277
3.427
3.788
8
Table 2. Overview over the time period 1999-2007 for the number of papers (N) in
limnological journals, the percentage of papers in relation to limnological papers of all
countries of the world (N%), the weighted mean journal impact factor, the relative impact
factor, the number of references, the percentage of references, the mean references per article,
and the citation quotient.
Brazil
India
Mexico
PR China
Russia
South Africa
Germany
USA
Sum
All countries
of the world
Mean
Relative
% Refer- References/ Citation
N
% N IF
IF
References ences
article
quotient
0.78
1074 2.26
1.07
4701
1.32
4.38
0.58
0.82
657 1.38
1.11
3496
0.98
5.32
0.71
0.87
823 1.73
1.18
4307
1.21
5.23
0.70
0.99
1583 3.33
1.34
8782
2.47
5.55
0.74
0.83
482 1.01
1.13
2621
0.74
5.44
0.73
0.90
415 0.87
1.22
2482
0.70
5.98
0.80
0.97
3397 7.14
1.32
28208
7.93
8.30
1.11
1.15
14118 29.69
1.56
123986
34.83
8.78
1.17
22549 47.43
178583
50.17
47545
1.36
1.00
355935
7.49
1.00
9
Table 3. Analysis of Variance of the number of papers of 6 BRIC and outreach states in 9
years. The Bonferroni-adjusted F-table thresholds were Fdf = 8, 40 = 2.993 (P < 0.01) for the
year and Fdf = 5, 40 = 4.966 (P < 0.01) for the country. DF = degrees of freedom.
Sum of
Mean
Variability Squares
DF Squares
F-value
Total
178197 53
Year
30471
8
3809
3.607
Country
105485
5
21097
19.978
Residuals
42242 40
1056
10
Table 4. Analysis of Variance of the mean impact factors of 6 BRIC and Outreach states in 9
years. The Bonferroni-adjusted F-table thresholds were Fdf = 8, 40 = 2.993 (P < 0.01) for the
year and Fdf = 5, 40 = 3.637 (P < 0.05) for the country.
Sum of
Mean
Variability Squares DF
Squares F-value
Total
5.3435
53
Year
4.2459
8 0.5307 29.698
Country
0.3828
5 0.0766
4.284
Residuals
0.7148
40 0.0179
11
Table 5. a) Development of the number of papers from 1999-2007. b) Development of the
percentage of papers from the total number of papers of all countries.
a) N
Brazil
India
Mexico
PR China
Russia
South Africa
Germany
USA
Sum
1999
71
56
74
55
42
66
338
1403
4804
2000
71
62
64
98
63
38
343
1363
4658
2001
131
74
73
143
34
60
336
1500
5020
2002
108
57
103
121
52
41
380
1449
5044
2003
103
58
84
173
46
43
392
1466
5097
2004
98
88
113
225
64
42
435
1559
5409
2005
122
81
96
205
37
32
434
1577
5575
2006
180
91
118
279
90
54
408
1882
6274
2007
190
90
98
284
54
39
331
1919
5664
b) N%
Brazil
India
Mexico
PR China
Russia
South Africa
Germany
USA
Sum
1.48
1.17
1.54
1.14
0.87
1.37
7.04
29.20
43.82
1.52
1.33
1.37
2.10
1.35
0.82
7.36
29.26
45.13
2.61
1.47
1.45
2.85
0.68
1.20
6.69
29.88
46.83
2.14
1.13
2.04
2.40
1.03
0.81
7.53
28.73
45.82
2.02
1.14
1.65
3.39
0.90
0.84
7.69
28.76
46.40
1.81
1.63
2.09
4.16
1.18
0.78
8.04
28.82
48.51
2.19
1.45
1.72
3.68
0.66
0.57
7.78
28.29
46.35
2.87
1.45
1.88
4.45
1.43
0.86
6.50
30.00
49.44
3.35
1.59
1.73
5.01
0.95
0.69
5.84
33.88
53.05
12
Table 6. Analysis of Covariance for the slopes and intercepts of the exponential growth rates.
The Bonferroni-adjusted thresholds were Fdf = 7, 56 = 4.020 (P < 0.01) for the slopes and Fdf
=7, 63 = 3.945 (P < 0.01) for the intercepts.
Slope
Sum of
Variability Squares
DF
Total
3.6853
Between
1.7915
Residuals
1.8937
Mean
Squares
63
7
56
Intercept
Variability SS
Total
Between
Residuals
70
7
63
DF
91.724
88.039
3.6853
0.2559
0.0338
MS
F-value
7.568
F-value
12.5769 215.004
0.0585
13
Table 7. Analysis of Covariance for the slopes and intercepts for the increase of the impact
factors. The Bonferroni-adjusted thresholds were Fdf = 8, 63 = 3.7863 (P < 0.01) for the slopes
and Fdf = 8, 71 = 3.7863 (P < 0.01) for the intercepts.
Slope
Sum of
Mean
Variability squares
DF
squares
F
Total
2.6318
71
Between
0.1687
8
0.0211 0.5395
Residuals
2.463
63
0.0391
Intercept
Variability SS
Total
Between
Residuals
DF
4.5578
1.9261
28,318
MS
79
8
71
F
0.2408
0.0371
6.4953
14
Figure legends
Figure 1. Relationship between Gross Expenditure on Research and Development (GERD) in
2005 and the number of papers in 2007.
Figure 2. Exponential growth rate of the number of papers from 1999 to 2007.
Figure 3. Development of the mean country impact factors from 1999 to 2007.
Figure 4. Percentage of publications in journals of different disciplines of limnology. The
arrows indicate the tendency for a significant increase or decrease (P < 0.05) during the
period 1999-2007..
15
2000
Number of Papers
1500
1000
500
0
0
50
100
150
200
250
300
350
GERD (Billion PPP US$)
Figure 1. Relationship between Gross Expenditure on Research and Development (GERD) in
2005 and the number of papers in 2007.
16
-1
Exponential Growth Rate (y )
0.25
PR China
0.20
0.15
Brazil
0.10
India Mexico
0.05
Russia
USA
Germany
0.00
-0.05
South Africa
-0.10
Figure 2. Exponential growth rate of the number of papers from 1999-2007.
17
2.50
Brazil
India
Mexico
Mean Journal Impactfactor
PR China
2.00
Russia
South Africa
Germany
USA
All countries
1.50
1.00
0.50
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
Figure 3. Development of the relative mean impact factors.
18
8.0
Brazil
India
7.0
Mexico
PR China
Russia
6.0
% All Countries
South Africa
5.0
4.0
3.0
2.0
1.0
0.0
General
Applied
Fish
Phycology
Microbiology
Figure 4. Percentage of publications in journals of different disciplines of limnology. The
arrows indicate tendency for a significant increase or decrease (P < 0.05).
19