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2. Global patterns of stream detritivore distribution: implications for biodiversity loss in changing climates

Author

Boyero, Luz, Pearson, Richard G., Dudgeon, David, Ferreira, Verónica, Graça, Manuel A. S., Gessner, Mark O., Boulton, Andrew J., Chauvet, Eric, Yule, Catherine M., Albariño, Ricardo J., Ramírez, Alonso, Helson, Julie E., Callisto, Marcos, Arunachalam, Muthukumarasamy, Chará, Julián, Figueroa, Ricardo, Mathooko, Jude M., Gonçalves, José F., Moretti, Marcelo S., Chará-Serna, Ana Marcela, Davies, Judy N., Encalada, Andrea, Lamothe, Sylvain, Buria, Leonardo M., Castela, José, Cornejo, Aydeé, Li, Aggie O. Y., M'Erimba, Charles, Villanueva, Verónica Díaz, del Carmen Zúñiga, María, Swan, Christopher M., and Barmuta, Leon A.

Published
2012
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5. Latitudinal gradient of nestedness and its potential drivers in stream detritivores

Author

Boyero, Luz, Pearson, Richard G., Swan, Christopher M., Hui, Cang, Albariño, Ricardo J., Arunachalam, Muthukumarasamy, Callisto, Marcos, Chará, Julián, Chará-Serna, Ana M., Chauvet, Eric, Cornejo, Aydeé, Dudgeon, David, Encalada, Andrea C., Ferreira, Verónica, Gessner, Mark O., Gonçalves, José F., Jr, Graça, Manuel A. S., Helson, Julie E., Mathooko, Jude M., McKie, Brendan G., Moretti, Marcelo S., and Yule, Catherine M.

Published
2015
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14. Contributors

Author

Agostinho, Angelo A., primary, Boulton, Andrew J., additional, Boyero, Luz, additional, Bunn, Stuart E., additional, Caramaschi, Érica Pellegrini, additional, Covich, Alan P., additional, Cressa, Claudia, additional, Davies, Peter M., additional, Dobson, Michael, additional, Dudgeon, David, additional, Hamilton, Stephen K., additional, Harper, David M., additional, Jacobsen, Dean, additional, Junk, Wolfgang J., additional, Lake, Sam, additional, Lewis, William M., additional, Mathooko, Jude M., additional, Pacini, Nic, additional, Pearson, Richard, additional, Pringle, Catherine M., additional, Ramírez, Alonso, additional, Tockner, Klement, additional, Wantzen, Karl M., additional, Winemiller, Kirk O., additional, and Yule, Catherine M., additional

Published
2008
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17. Global patterns of distribution in stream detritivores: implications for biodiversity loss in changing climates

Author

Boyero, Luz, Pearson, Richard G., Dudgeon, David, Ferreira, Verónica, Graça, Manuel A. S., Gessner, Mark O., Boulton, Andrew J., Chauvet, Eric, Yule, Catherine M., Albariño, Ricardo J., Ramírez, Alonso, Helson, Julie E., Callisto, Marcos, Arunachalam, Muthukumarasamy, Chará, Julián, Figueroa, Ricardo, Mathooko, Jude M., Gonçalves, José F. Jr, Moretti, Marcelo S., Chará-Serna, Ana Marcela, Davies, Judy N., Encalada, Andrea, Lamothe, Sylvain, Buria, Leonardo M., Castela, José, Cornejo, Aydeé, Li, Aggie O. Y., M'Erimba, Charles, Villanueva, Verónica Díaz, Zúñiga, Maria Del Carmen, Swan, Christopher M., Barmuta, Leon A., Centre National de la Recherche Scientifique - CNRS (FRANCE), Consejo Superior de Investigaciones Científicas - CSIC (SPAIN), Universidade de Coimbra (PORTUGAL), University of Hong Kong - HKU (CHINA), Institut National Polytechnique de Toulouse - Toulouse INP (FRANCE), James Cook University - JCU (AUSTRALIA), Monash University (MALAYSIA), Universidad de Concepción - UDEC (CHILE), Université Toulouse III - Paul Sabatier - UT3 (FRANCE), University of Maryland (USA), University of Toronto (CANADA), Centro para la investigaciòn en Sistemas Sostenibles de producciòn agropecuaria - CIPAV (COLOMBIA), Swiss Federal Institute of Aquatic Science and Technology - EAWAG (SWITZERLAND), Egerton university (KENYA), Manonmaniam Sundaranar university (INDIA), Universidade Federal de Minas Gerais - UFMG (BRAZIL), Universidad Nacional del Comahue (ARGENTINA), University of New England - UNE (AUSTRALIA), Universidad de Panamà (PANAMA), Universidad de Puerto Rico - UPR (PUERTO RICO), Universidad San Francisco de Quito - USFQ (ECUADOR), University of Tasmania (AUSTRALIA), Marine and environmental research center - IMAR-CMA (Coimbra, Portugal), Ecosystem management (Armidale, Australia), Laboratory of limnology (Bariloche, Argentina), Laboratorio de Ecologia de Bentos (Belo Horizonte, Brazil), Aquatic Systems Research Unit (Concepcion, Chile), Freshwater ecology group (Hobart, Tasmania), Institut National Polytechnique de Toulouse - INPT (FRANCE), Wetland ecology department (Seville, Espagne), Estación Biológica de Doñana (EBD), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC)-Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), James Cook University (JCU), The University of Hong Kong (HKU), Marine and environmental research centre - IMAR-CMA (Coimbra, Portugal), University of Coimbra [Portugal] (UC), Swiss Federal Insitute of Aquatic Science and Technology [Dübendorf] (EAWAG), Ecosystem Management, Armidale, University of New England (UNE), Laboratoire Ecologie Fonctionnelle et Environnement (LEFE), Institut Ecologie et Environnement (INEE), Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT), Monash University [Malaysia], Laboratorio de Limnología [Bariloche], Instituto Nacional de Investigaciones en Biodiversidad y Medioambiente [Bariloche] (INIBIOMA-CONICET), Consejo Nacional de Investigaciones Científicas y Técnicas [Buenos Aires] (CONICET)-Universidad Nacional del Comahue [Neuquén] (UNCOMA)-Consejo Nacional de Investigaciones Científicas y Técnicas [Buenos Aires] (CONICET)-Universidad Nacional del Comahue [Neuquén] (UNCOMA), Institute for tropical ecosystem studies - ITES (San Juan, Puerto Rico), University of Puerto Rico (UPR), Department of biolological sciences (Toronto, Canada), University of Toronto, Laboratorio de ecologia de Bentos (Belo Horizonte, Brazil), Universidade Federal de Minas Gerais [Belo Horizonte] (UFMG), Sri Paramakalyani Centre for Environmental Sciences - SPKCES (Alwarkuruchi, India), Manonmainam Sundaranar university (INDIA, Centro para la Investigacion en sistemas Sostenibles de Produccion Agropecuaria - CIPAV (COLOMBIA), Universidad de Concepción - University of Concepcion [Chile], Department of biological sciences [Egerton], Egerton University, Universidad San Francisco de Quito (EQUATEUR), Universidad San Francisco de Quito (USFQ), University of Panama (PANAMA), Department of Geography and Environmental Systems [Baltimore], University of Maryland [Baltimore County] (UMBC), University of Maryland System-University of Maryland System, University of Tasmania [Hobart, Australia] (UTAS), James Cook university (AUSTRALIA), Laboratoire Ecologie Fonctionnelle et Environnement (ECOLAB), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées, and Universidad de Concepción [Chile]

Subjects
[SDV.EE]Life Sciences [q-bio]/Ecology, environment, Ecologie, Environnement, Diversity, [SDE.MCG]Environmental Sciences/Global Changes, Biodiversité et Ecologie, Guild, Leaf litter, [SDV.BID]Life Sciences [q-bio]/Biodiversity, respiratory system, Latitudinal gradient, Detritus, Shredders, Biodiversité, [SDE.BE]Environmental Sciences/Biodiversity and Ecology, Milieux et Changements globaux, human activities, Trophic diversity, Stream ecosystems, Species richness
Abstract

International audience; Aim. We tested the hypothesis that shredder detritivores, a key trophic guild in stream ecosystems, are more diverse at higher latitudes, which has important ecological implications in the face of potential biodiversity losses that are expected as a result of climate change. We also explored the dependence of local shredder diversity on the regional species pool across latitudes, and examined the influence of environ- mental factors on shredder diversity. Location: World-wide (156 sites from 17 regions located in all inhabited continents at latitudes ranging from 67° N to 41° S). Methods: We used linear regression to examine the latitudinal variation in shredder diversity at different spatial scales: alpha (a), gamma (g) and beta (b) diversity. We also explored the effect of g-diversity on a-diversity across latitudes with regression analysis, and the possible influence of local environmental factors on shredder diversity with simple correlations. Results: Alpha diversity increased with latitude, while g- and b-diversity showed no clear latitudinal pattern. Temperate sites showed a linear relationship between g- and a-diversity; in contrast, tropical sites showed evidence of local species saturation, which may explain why the latitudinal gradient in a-diversity is not accompanied by a gradient in g-diversity. Alpha diversity was related to several local habitat characteristics, but g- and b-diversity were not related to any of the environmental factors measured. Main conclusions: Our results indicate that global patterns of shredder diversity are complex and depend on spatial scale. However, we can draw several conclusions that have important ecological implications. Alpha diversity is limited at tropical sites by local factors, implying a higher risk of loss of key species or the whole shredder guild (the latter implying the loss of trophic diversity). Even if regional species pools are not particularly species poor in the tropics, colonization from adjacent sites may be limited. Moreover, many shredder species belong to cool-adapted taxa that may be close to their thermal maxima in the tropics, which makes them more vulnerable to climate warming. Our results suggest that tropical streams require specific scientific attention and conservation efforts to prevent loss of shredder biodiversity and serious alteration of ecosystem processes.

Published
2012

18. A global experiment suggests climate warming will not accelerate litter decomposition in streams but might reduce carbon sequestration

Author

Boyero, Luz, Pearson, Richard G., Gessner, Mark O., Barmuta, Leon A., Ferreira, Verónica, Graça, Manuel A. S., Dudgeon, David, Boulton, Andrew J., Callisto, Marcos, Chauvet, Eric, Helson, Julie E., Bruder, Andreas, Albariño, Ricardo J., Yule, Catherine M., Arunachalam, Muthukumarasamy, Davies, Judy N., Figueroa, Ricardo, Flecker, Alexander S., Ramírez, Alonso, Death, Russell G., Iwata, Tomoya, Mathooko, Jude M., Mathuriau, Catherine, Gonçalves, José F. Jr, Moretti, Marcelo S., Jinggut, Tajang, Lamothe, Sylvain, M'Erimba, Charles, Ratnarajah, Lavenia, Schindler, Markus, Castela, José, Buria, Leonardo M., Cornejo, Aydeé, Villanueva, Verónica Díaz, West, Derek C., Centre National de la Recherche Scientifique - CNRS (FRANCE), Consejo Superior de Investigaciones Científicas - CSIC (SPAIN), Universidade de Coimbra (PORTUGAL), Cornell University (USA), University of Hong Kong - HKU (CHINA), Instituto Conmemorativo Gorgas de Estudios de la Salud - ICGES (PANAMA), Institut National Polytechnique de Toulouse - Toulouse INP (FRANCE), James Cook University - JCU (AUSTRALIA), Massey University (NEW ZEALAND), Monash University (MALAYSIA), Universidad de Concepción - UDEC (CHILE), Universidad Nacional Autónoma de México - UNAM (MEXICO), Université Toulouse III - Paul Sabatier - UT3 (FRANCE), University of Toronto (CANADA), University of Yamanashi (JAPAN), Swiss Federal Institute of Aquatic Science and Technology - EAWAG (SWITZERLAND), Egerton university (KENYA), Manonmaniam Sundaranar university (INDIA), Eidgenössische Technische Hochschule Zürich - ETHZ (SWITZERLAND), Universidade Federal de Minas Gerais - UFMG (BRAZIL), Universidad Nacional del Comahue (ARGENTINA), University of New England - UNE (AUSTRALIA), Universidad de Panamà (PANAMA), Universidad de Puerto Rico - UPR (PUERTO RICO), University of Tasmania (AUSTRALIA), Laboratorio de Ecologia de Bentos (Belo Horizonte, Brazil), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), James Cook University (JCU), Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich] (ETH Zürich), Swiss Federal Insitute of Aquatic Science and Technology [Dübendorf] (EAWAG), University of Tasmania [Hobart, Australia] (UTAS), Universidade de Coimbra [Coimbra], The University of Hong Kong (HKU), University of New England (UNE), Laboratorio de ecologia de Bentos (Belo Horizonte, Brazil), Universidade Federal de Minas Gerais [Belo Horizonte] (UFMG), Laboratoire Ecologie Fonctionnelle et Environnement (ECOLAB), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut Ecologie et Environnement (INEE), Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), University of Toronto, Laboratorio de Limnología [Bariloche], Instituto Nacional de Investigaciones en Biodiversidad y Medioambiente [Bariloche] (INIBIOMA-CONICET), Consejo Nacional de Investigaciones Científicas y Técnicas [Buenos Aires] (CONICET)-Universidad Nacional del Comahue [Neuquén] (UNCOMA)-Consejo Nacional de Investigaciones Científicas y Técnicas [Buenos Aires] (CONICET)-Universidad Nacional del Comahue [Neuquén] (UNCOMA), Monash University [Malaysia], Universidad de Concepción - University of Concepcion [Chile], Cornell University [New York], University of Puerto Rico (UPR), Massey University, Yamanashi University, Egerton University, Universidad de Panamá, Laboratoire Ecologie Fonctionnelle et Environnement (LEFE), Institut Ecologie et Environnement (INEE), Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), and Université de Toulouse (UT)

Subjects
Ecologie, Environnement, Carbon Sequestration, Litter decomposition, Temperature, Fresh Water, Carbon cycle, Carbon Dioxide, Plants, Latitudinal gradient, Plant Leaves, Streams, Climate change, Detritivores, Microbial decomposers, [SDV.EE.BIO]Life Sciences [q-bio]/Ecology, environment/Bioclimatology, Ecosystem, Global analysis
Abstract

International audience; The decomposition of plant litter is one of the most important ecosystem processes in the biosphere and is particularly sensitive to climate warming. Aquatic ecosystems are well suited to studying warming effects on decomposition because the otherwise confounding influence of moisture is constant. By using a latitudinal temperature gradient in an unprecedented global experiment in streams, we found that climate warming will likely hasten microbial litter decomposition and produce an equivalent decline in detritivore-mediated decomposition rates. As a result, overall decomposition rates should remain unchanged. Nevertheless, the process would be profoundly altered, because the shift in importance from detritivores to microbes in warm climates would likely increase CO2 production and decrease the generation and sequestration of recalcitrant organic particles. In view of recent estimates showing that inland waters are a significant component of the global carbon cycle, this implies consequences for global biogeochemistry and a possible positive climate feedback.

Published
2011

22. Global patterns of stream detritivore distribution: implications for biodiversity loss in changing climates

Author

Boyero, Luz, primary, Pearson, Richard G., additional, Dudgeon, David, additional, Ferreira, Verónica, additional, Graça, Manuel A. S., additional, Gessner, Mark O., additional, Boulton, Andrew J., additional, Chauvet, Eric, additional, Yule, Catherine M., additional, Albariño, Ricardo J., additional, Ramírez, Alonso, additional, Helson, Julie E., additional, Callisto, Marcos, additional, Arunachalam, Muthukumarasamy, additional, Chará, Julián, additional, Figueroa, Ricardo, additional, Mathooko, Jude M., additional, Gonçalves Jr, José F., additional, Moretti, Marcelo S., additional, Chará-Serna, Ana Marcela, additional, Davies, Judy N., additional, Encalada, Andrea, additional, Lamothe, Sylvain, additional, Buria, Leonardo M., additional, Castela, José, additional, Cornejo, Aydeé, additional, Li, Aggie O. Y., additional, M'Erimba, Charles, additional, Villanueva, Verónica Díaz, additional, del Carmen Zúñiga, María, additional, Swan, Christopher M., additional, and Barmuta, Leon A., additional

Published
2011
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36. Adult males dominate water abstraction at the middle reaches of a rural stream in south-western Kenya.

Author

Yillia, Paul, Kreuzinger, Norbert, and Mathooko, Jude M

Subjects
WATER management, WATER supply, RURAL sociology, RURAL geography, FLUID dynamics, RIVER conservation, ENVIRONMENTAL protection, RIVERS
Abstract

In rural sub-Saharan Africa, small scale water abstraction could be described as the manual withdrawal of water usually from the banks of shallow surface water systems by people with the aid of 10- and/or 20-litre containers mainly for domestic use. The gender composition of human visitors during water abstraction at the middle and upper reaches of a predominantly rural stream (Njoro River) in Southwestern Kenya was analyzed. Abstraction started at dawn with adult females accompanied by girls. But adult males who were mostly water vendors dominated, contributing > 65% of the daily total visits on weekdays. The number of children at the stream in the morning, as well as early in the afternoon of weekdays was < 15% but they accounted for approximately 40% of the evening total and > 70% of the daily total visits on weekends. The dominance of adult males coupled with the low participation of children, especially on weekdays suggested that water abstraction in the Njoro area was not an important activity for most children. This information could be relevant for the development and/or refinement of policy and targeted programmes on water supply in the area. [ABSTRACT FROM AUTHOR]

Published
2008
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37. Modifying Surber sampling technique increases capture of freshwater crabs in African upland streams

Author

Magana, Adiel M., Dobson, Michael, and Mathooko, Jude M.

Abstract

AbstractWe compared 2 methods for sampling the freshwater crab Potamonautes odhneri(Colosi) in Kenyan streams: standard Surber sampling, in which a sample is taken over a period of several minutes; and rapid Surber sampling, in which the process is reduced to around 10 seconds. Rapid Surber sampling caught more crabs than standard Surber sampling, This suggests that the crab species investigated is normally able to evade capture if sampling is carried out at an unhurried pace, but that if precision is sacrificed for speed, then capture efficiency increases. The size of crabs caught using the 2 techniques was similar, and use of baited traps set in the same locations showed that Surber sampling methods were not capturing larger individuals. Like all methods available to sample large benthic crustaceans, rapid Surber sampling has its limitations, but this study demonstrates that it can be used as a method for rapid assessment of crab presence and for comparative determination of population density, to significantly greater effect than the standard method of Surber sampling.

Published
2012
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39. Distributional Patterns of Diatoms and Limnodrilus Oligochaetes in a Kenyan Dry Streambed Following the 1999–2000 Drought Conditions

Author

Mathooko, Jude M., Mpawenayo, Balthazar, Kipkemboi, Julius K., and M'erimba, Charles M.

Abstract

Drought is a natural phenomenon experienced by many intermittent and also seasonal lotic systems. It has diverse effects on the structure and distribution of biological communities through habitat transition from wetted to terrestrial conditions. The Njoro River, a tropical stream, was drought-stressed between late 1999 and mid 2000, providing an opportunity to sample and describe the distributional patterns of diatoms and Limnodrilus oligochaetes in the vertical sediment profile. The dispersion of Limnodrilus oligochaetes with sediment depth profile varied from quasi-random (i.e. exponent k of the negative binomial distribution >2.0 or <0) at the surface to strong aggregation (0 < k < 1.0) in the deeper sediments. Diatoms were heterogenous, with most species contributing less than 1% of all the diatoms collected from the riverbed. Contagious dispersion was a common feature among the diatom species. The distribution of Fragilaria ulna was largely quasi-random in all sites, with Nitzschia amphibia and Cocconeis placentula demonstrating quasi-random distribution in the Kerma vertical sediment profile. Escape from stranding to deeper sediment strata as the drought progressed was not a universal response among the diatom species. Our results showed that drought-stress altered the structure of biological assemblages and also emphasized the need for the management of tropical lotic systems and their catchments for flow permanence. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Published
2005
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40. THE EFFECTS OF PHYSICAL DISTURBANCE ON AFROPTILUM SUDAFRICANUM(EPHEMEROPTERA: BAETIDAE) POPULATION DENSITIES IN A KENYAN MOUNTAIN STREAM

Author

Mathooko, Jude M.

Abstract

SummaryThe effects of physical disturbance on larval populations of the mayfly Afroptilum sudafricanumLestage were examined in the Naro Morn River, Kenya. Disturbance was induced by stirring, shifting and relocating streambed substrates by hand. The method aimed to simulate natural physical disturbance. The effects of continuous disturbance were examined by sampling larval populations at minute intervals of up to 14 minutes. The effects of periodic disturbance were examined by sampling larval populations which had been disturbed at intervals of minutes (short-term), hours (medium-term) and days (long-term). About 85% of A. sudafricanumindividuals was removed from the streambed within four minutes of continuous physical disturbance. There were higher densities at night than during the day. All densities on the control sites for the medium-term disturbance experiments were significantly higher than those on the disturbed sites. Most of the post-disturbance densities on the medium-term disturbance sites were significantly lower than the pre-disturbance densities (Tukey's honestly significance difference test, α=0.05). There was no distinct density pattern on the sites exposed to long-term disturbances. Sites with the same disturbance regime appeared to react differently, some having dramatic fluctuations in density. Disturbance effects on A. sudafricanumdensity were multi-faceted with different expressions in time and space. It is concluded that A. sudafricanumis highly mobile and is capable of recolonizing disturbed areas within six hours. Their high mobility enables them to crawl into the deeper sediment layers during floods. However, recovery time depended not only on species mobility but also on how densely the sources of recolonization were populated and the frequency of disturbance. Slight increases, strong declines and negligible disturbance effects on the density of A. sudafricanumwere evident. Afroptilum sudafricanumis highly mobile and is capable of rapid recolonization. It is concluded that physical disturbance affects A. sudafricanumpopulations in the Naro Morn River.

Published
1998
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41. Decomposition of leaf litter of Dombeya goetzenii in the Njoro River, Kenya

Author

Leichtfried, Maria, Mathooko, Jude M., and M'Erimba, Charles M.

Subjects
BIODEGRADATION, WATER quality
Abstract

Decomposition of the leaves of Dombeya goetzenii (K. Schum) in the Njoro River is described and analysed. The loss of the ash-free dry mass was rapid during the first 14 d of exposure in the wet and humid zones. The leaves in the litter bags in the humid and wet zones were processed at a rate (plus or minus SD) of 0.005 plus or minus 0.001 d-1 and 0.021 plus or minus 0.001 d-1, respectively. The processing rates of the leaves in the wet zone differed significantly from those observed in the humid zone ( t-value, p<0.05). The interchanged litter bags (i.e. from wet to humid zones vice versa) showed that the processing rates of the leaves in the litter bags interchanged from the wet zone to the humid zone was about 200 times lower than that of the leaves retained in the wet zone throughout; fourfold higher in the leaves in the litter bags which were transferred tothe wet zone than in those leaves of the litter bags which were retained in the humid zone throughout the experiment. It took approximately 38 months for 90% of the leaf dry mass to be processed in the humid zone whilst it took 4 months for a similar percentage to be processed in the wet zone. It is concluded that the immersion and emersion of leaf litter, which may occur in the wet and humid zones, respectively, are important aspects of the decomposition process which may influence the quantity of nutrients in stream ecosystems. [ABSTRACT FROM AUTHOR]

Published
2000
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