DOI: 10.5061/dryad.c2fqz61fn
title: Discordant spatio-temporal dynamics of functional and phylogenetic diversity of rotiferan communities exposed to aquaculture effluent

description: The growth of the human population brought about the global
 intensification of aquacultural production, and aquaculture became the
 fastest growing animal husbandry sector. Effluent from aquaculture is an
 anthropogenic environmental burden, containing organic matter, nutrients,
 and suspended solids that affect water quality, especially in water bodies
 of high biodiversity and conservation value. Water quality assessment
 often relies on bioindicators, analysing changes in taxonomic diversity of
 various freshwater organismal groups. Stepping beyond taxon diversity, we
 used functional and phylogenetic diversities of rotifers to identify
 factors affecting their community organization in response to an
 aquaculture effluent gradient in the largest oxbow lake in the Carpathian
 Basin, Hungary. Sampling was carried out three times per season at five
 points along a 3.5 km section of the oxbow lake, including the point of
 effluent inflow. We used eight traits to evaluate functional diversity:
 body size, trophi type, feeding mode, protection type, body wall type,
 corona type, habitat preference, and tolerance level. Functional and
 phylogenetic distances among the 24 species identified indicated trait
 conservatism. Rotiferan diversity increased with increasing distance from
 the point of influx in spring and summer. Among the factors affecting
 community organization in spring and summer, we find examples of
 environmental filtering, while in autumn the role of biotic interaction is
 more frequent. Under nutrient-rich conditions in spring and summer,
 organisms belonging to the same functional group were dominant, while
 under oligotrophic conditions more diverse but less abundant groups were
 present. Considering functional and phylogenetic traits allowed us to
 identify organising forces of rotifer communities in the largest oxbow
 lake of the Hungarian Lowland.
description: The Kákafok oxbow lake,
 stretching between the south Hungarian settlements of Szarvas and
 Békésszentandrás (46° 51' 14.9''N, 20° 30'
 44.6''E) is 29 km long and was separated from the River Körös
 during the 19th-century river regulations. Five sampling points (K1 – K5)
 were selected along a 3.5 km long section of the oxbow lake. The first of
 these is the introduction point for effluent water from an intensive
 African catfish (<em>Clarias gariepinus</em>) warm-water farm
 and the experimental fish ponds of the Research Centre for Aquaculture and
 Fisheries – Hungarian University of Agriculture and Life Sciences. The
 other four sampling sites were located at different distances from this
 point: at 500m (K2), 2500m (K3), 3000m (K4), and 3500 m (K5) from the
 point of effluent. An intensive fish survey along a ca. 2km long section
 prevented us from sampling there. Rotifers were sampled three times during each
 season: in spring (20 April, 10 May, 1 June), summer (29 June, 21 July, 10
 August), and autumn (30 August, 21 September, 24 October) of 2016. Each
 time, 50 l of surface water at each point was filtered through a 50 µm
 mesh plankton net, concentrated to 100 ml, preserved by the addition of
 formaldehyde (4% final concentration) and stored at
 4<strong>°</strong> C until
 identification. Counting was performed with a 5 ml counting chamber using
 a microscope (40-125x magnification). Species were identified using
 standard keys (Bancsi 1986, 1988).
 REFERENCES 
 Bancsi, I., 1986.
 Identification keys for Rotifera I. Vízügyi Hidrobiológia, 15. Országos
 Vízügyi Hivatal, Budapest. [In Hungarian]
 Bancsi, I., 1988.
 Identification keys for Rotifera II. Vízügyi Hidrobiológia 17. Országos
 Vízügyi Hivatal, Budapest. [In Hungarian]