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Analysis of zooplankton assemblages from man-made ditches in relation to current velocity

Czerniawski R., Sługocki Ł

Oceanological and Hydrobiological Studies

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2017

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Vol. 46, No. 2

199--211

EN

Because of the slow current velocity, man-made ditches may create distinct physical and ecological conditions that are suitable for the growth of zooplankton populations. However, the influence of drainage ditches on zooplankton communities has not been studied yet. This study aims to answer the following questions: i) Are man-made ditches a rich source of zooplankton? ii) What current velocity value leads to abundant zooplankton in man-made ditches? iii) Do zooplankton communities differ between man-made ditches and connected natural streams? In man-made drainage ditches with a water current lower than 0.1 m s-1, the abundance of zooplankton was greater than in the majority of streams. Sometimes this level of abundance was equivalent to the densities of zooplankton in lakes or dammed reservoirs. The presence of zooplankton in man-made ditches may be of great importance to the establishment of food webs, particularly during periods of high water levels or heavy rainfall, both of which may accelerate the water current, causing the dispersion of zooplankton along the ditches and into natural streams.

2

Leaf litter decomposition and invertebrate colonization in Alpine environments above the tree line: an experimental study

Bo T., Cammarata M., López-Rodríguez M. J., Tierno de Figueroa J. M., Fenoglio S.

Polish Journal of Ecology

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2014

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Vol. 62, nr 2

217--225

EN

Recent studies suggested a general warming trend in the Alps, resulting in a significant migration of forests to altitudes higher than the usual, regional tree line. As a consequence, some headwater streams will likely receive more allochthonous organic matter. For this reason, the dynamics of decomposition of terrestrial leaf detritus in stream reaches that naturally lacked this resource represents a subject of considerable interest, on which no information is currently available. The aim of this study was to analyse breakdown and macroinvertebrate colonisation of leaf bags in an Alpine headwater stream above the tree line. Results of this study indicate that decomposition of terrestrial leaves in a lotic alpine environment above the tree line takes place through a process similar to what happens at lower altitudes, but with some differences. The reduced rate of decomposition observed may be due to lower temperatures. At lower altitudes, tree cover provides a supply of organic material sufficient to support a rich guild of shredders. This study demonstrates that also above tree line, where communities are dominated by scrapers, an important part of the benthic community take part in the decomposition process of leaves. We can conclude that streams above the tree line, while hosting invertebrate communities dominated by rhithrophilous organisms that feed mostly on biofilm, also harbour a rich population of opportunist invertebrates. It seems that, in the case of expected temperature increase at higher altitudes , terrestrial organic detritus may be actively degraded by lotic benthic communities.

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Spatial pattern of potamozooplankton community of the slowly flowing fishless stream in relation to abiotic and biotic factors

Czerniawski R.

Polish Journal of Ecology

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2012

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Vol. 60, nr 2

323-338

EN

While the knowledge about spatial structure of zooplankton communities in large rivers has been relatively well studied, little is known on the longitudinal spatial variation of zooplankton in small, slowly flowing fishless streams. In these streams, changes in zooplankton communities along entire length of the stream can be quite different than in those where young planktivorous stages of fish reduce the abundance of zooplankton. The aim of this study was to answer the following questions. What is the spatial pattern of the taxonomic groups of zooplankton in the slow-flowing stream? Do the small tributaries have an impact on the zooplankton community in the main stream? What biotic variables (content of chlorophyll a, vegetation coverage, macroinvertebrates abundance) and abiotic variables (temperature, dissolved oxygen, pH, conductivity, N-NO3, N-NO2, N-NH3, TN, P-PO4, TP, width, depth, current velocity, discharge) most affect the zooplankton community in a small stream? This study was performed at six sites along a small (1 km long, mean width 1.7 m; mean depth 0.3 m; mean current velocity 5.9 cm s[^-1]; mean discharge 2.6 cm3 s[^-1], mean vegetation coverage 52%) fishless agricultural-meadow stream and at one site in its two tributaries. The stream was searched with the use of electric fish gear to make sure there were no fish. Zooplankton samples were collected each month throughout the years 2008 and 2009. The main factors which affected the zooplankton communities were hydrological conditions, especially current velocity. Water current in the stream impeded the movement of rotifers and juvenile copepods. Adult copepods were able to manage in the current, over the entire length of the stream. Cladocerans probably were only able to persist in the last section of the watercourse flow, where the velocity was the lowest (3.3 cm s[^-1) and where the content of chlorophyll a was the highest (56.2 [mu]g L[^-1]). The two tributaries had only a small effect on shaping of the zooplankton communities in the main stream. On the basis of Pearson correlations it can be concluded that macroinvertebrate had a low ability to reduce the density of zooplankton, all significant correlations between the abundance of potamozooplankton and that of macroinvertebrates were positive.

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Coupling of hydrodynamical, biological, and geochemical processes in streambeds

Packman A. I., Battin T. J., Newbold J. D.

Archives of Hydro-Engineering and Environmental Mechanics

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2003

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Vol. 50, nr 2

107-123

EN

Recent interest in the effects of streambed and near-subsurface (benthic and hyporheic) processes on stream ecosystems has motivated study of the hydrodynamics of stream-subsurface interactions. Hydrodynamic transport places an important control on the delivery of reactive species such as contaminants and ecologically-relevant substances such as nutrients to the benthic and hyporheic zones. Conversely, biological pro-cesses such as biofilm growth and physicochemical processes such as colloid deposition can alter the transport environment within sedimentary systems. Multiple feedbacks between biological, chemical, and transport processes make these interfacial sedimentary environments very com-plex. Experimental results are presented to illustrate the feedbacks be-tween hydrodynamic stream-subsurface exchange, biofilm development, and fine particle deposition. These studies demonstrate that a compre-hensive interdisciplinary approach is required to assess even the most basic dynamic processes in these systems, such as the evolution of in-terfacial fluxes over time. We suggest that it is useful to consider these processes to be biophysicochemical in nature. That is, in such complex environmental systems, it is misleading to attempt to consider processes in isolation; rather, understanding of system dynamics can only come from an integrated approach that considers feedbacks among and be-tween biological, physical, and chemical processes.