Disentangling food webs interactions in the littoral of temperate shallow lakes

Abstract

Elucidation of food web interactions provides a better understanding of ecosystem functioning, indicates anthropogenic impacts which often cause alterations in environmental conditions and deterioration in feeding networks in terrestrial and aquatic ecosystems. The importance of microfauna and macroinvertebrates in the littoral zones of shallow waters has been poorly studied regarding their trophic interactions. This study compares invertebrate assemblage and food web interactions among epiphyton, zooplankton and benthic macroinvertebrates across structural heterogeneity in the littoral zone of three temperate shallow water bodies. Submerged and structurally-complex stands of Ceratophyllum demersum inhabited a higher abundance of cladocerans and supported a higher diversity and biomass of epiphytic protozoans and invertebrates than floating-leaved Nuphar lutea stands. Analysis of the ecosystem functioning illustrated the increased biomass of macroinvertebrate predators and a preference of predation over planktonic crustaceans in more complex macrophyte stands. Food webs displayed higher complexity and size with habitat heterogeneity, while epiphyton and zooplankton shared an important fraction in food resources among the invertebrate trophic network. Results of food web modelling indicated zooplankton and epiphyton as more vulnerable to invertebrate predation in the complex submerged macrophytes than in the floating-leaved macrophyte stands. Integrated approaches to community, ecosystem and food webs in explanation of complex trophic interactions in the littoral zones confirmed an increase in diversity and food-web functional complexity with structural heterogeneity of microhabitats. Razjašnjenje interakcija u hranidbenoj mreži omogućuje bolje razumijevanje funkcioniranja ekosustava te indikaciju antropogenih učinaka koji često uzrokuju promjene uvjeta okoliša i narušavanje hranidbene mreže kopnenih i vodenih ekosustava. Trofičke interakcije mikrofaune i makrozoobentosa slabo su proučavane u priobalnim (litoralnim) zonama plitkih vodenih tijela. Cilj ovog rada je usporediti interakcije beskralježnjaka i izvora hrane, uključujući epifiton, zooplankton i makrozoobentos u strukturno heterogenim litoralnim zonama triju plikih jezera umjerenog pojasa. U submerznim i strukturno složenim makrofitskim sastojinama vrste Ceratophyllum demersum NAT. CROAT. VOL. 26 No 2 145-166 ZAGREB DECEMBER 31, 2017146 Špoljar, M. et al.: Disentangling food webs interactions in the littoral of temperate shallow lakes rašljoticalci su razvili populacije velike brojnosti, a također je u njima zbilježena veća raznolikost i biomasa epifitskih protozoa i beskralježnjaka u usporedbi sa sastojinama plutajuće vrste Nuphar lutea. Analiza funkcioniranja ekosustava ukazivala je na to da je u heterogenim makrofitskim sastojinama povećana biomasa makrozoobentoskih predatora i izraženija je njihova predacija nad planktonskim rakovima. Hranidbene mreže bile su složenije u heterogenima staništima, a epifiton i zooplankton imali su važan udio u hranidbe...

Substratum selection and feeding responses influence the demography of the sessile rotifer Cupelopagis vorax (Collothecacea: Atrochidae)

“…Predation by rotifers in freshwaters has important effects on prey communities including their species composition, nutrient cycling, and trophic dynamics (e.g., Edmondson, 1946; Gilbert, 1980; Miracle et al, 2007; Nandini & Sarma, 2005; Špoljar et al, 2017; Yoshida et al, 2003). While prey selectivity has been studied in several free‐swimming, raptorial species (Ardnt, 1993; Gilbert, 1977; Nandini et al, 2003; Nandini & Sarma, 2005; Williamson, 1983), little is known about the feeding of raptorial sessile species.…”

Small Standing-Water Ecosystems in the Transitional Temperate Climate of the Western Balkans

“…Hence, water mites (35%) prevailed among the hornwort (Ceratophyllum) coverage in Cro1, adult hemipterans (23%) overcome in Cro2, and in Cro5 dipteran larvae constituted a considerable share (51%) in the littoral ecotone zone, with very sparsely developed emergent macrophytes or their absence. Moreover, very important is possibility of refuge against predators in the sediment, due to results indicated an increased presence of buried planktonic crustaceans in the conditions of the increased abundance of macroinvertebrate predators, mainly dipteran and dragonfly larvae in the littoral zone [24,25]. Food web modelling indicated zooplankton and epiphyton as crucial food subsidies for invertebrate predators among complex submerged macrophyte than among the floating-leaved macrophyte stands (Fig.…”

“…Submerged macrophytes in the littoral zone enable the shelter to the largesized zooplankters against fish during the day. For many zooplankters littoral zone with macrophytes is not an adequate surviving solution, because there encounter macroinvertebrate, such as tactile predators [24,25]. Also, many studies suggested the existence of different alternative states at the same trophic conditions, where the absence of macrophyte coverage and presence of cyprinids could cause a shift into a turbid state [22,25].…”

“…Macroinvertebrates, mainly comprised of insect larvae, oligochaetes, gastropods and bivalves, are feeding on periphyton, algae and detritus, plant tissues or are predators that pray over other invertebrates. Complexity and heterogeneity of sediment, food subsidies, as well as macrophyte coverage affect macroinvertebrate assemblage in the littoral zone of SWE [7,24,25,51,52]. Sediment in the deeper zone is more uniform, as well as macroinvertebrate assemblage mainly consists of oligochaetes.…”

Seasonal Pattern in the Vertical Distribution of Dinoflagella in the Southern Caspian Sea

“…Dinoflagella are known because of their whip-like frills. Some of them live by photosynthesis, and some other types of plankton eat others [3] and some are able to produce light. Some of the plankton and fish parasites and others are able to secrete a toxic substance [4].…”