Utjecaj predacije riba na zooplankton u plitkim jezerima

master's thesis

• Title (english): Predation avoidance in shallow lakes
• Author: Maja Duić Sertić
• Mentor: Maria Špoljar (mentor)
• Committee member: Maria Špoljar (predsjednik povjerenstva)
• Committee member: Mirta Tkalec (član povjerenstva)
• Committee member: Jasna Hrenović (član povjerenstva)
• Committee member: Goran Kovačević (član povjerenstva)
• Granter: University of Zagreb; Faculty of Science; (Department of Biology); Zagreb
• Defense date and country: 2016-02-26, Croatia
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES; Biology

Abstract

Istraživanje zooplanktona provedeno je tijekom ljetnog razdoblja 2012. godine u tri vodena tijela
različitog postanka, morfometrije, stupnja trofije, prokrovnosti i sastava makrofita: na rukavcu rijeke
Sutle, mrtvaji Škrčev kut i šljunčari Zajarki. Osnovne hipoteze ovog rada bile su: (i) širina zone
makrofita i kompleksnost građe habitusa značajno utječu na raznolikost i brojnost zooplanktona i
predaciju riba; (ii) makrofitske sastojine utječu na abiotičke i biotičke čimbenike vodenih ekosustava.
Ciljevi istraživanja zooplanktona i ihtiofaune bili su utvrditi: 1) raznolikost i brojnost zooplanktona u
jezerima sa submerznim i flotantnim sastojinama; 2) utjecaj predacije riba na sastav i veličinsku
strukturu zooplanktona u jezerima s različitim sastojinama makrofita; 3) utjecaj makrofita i predacije
riba na brojnost ženki zooplanktona s jajašcima.
Analiza fizikalno-kemijskih čimbenika ukazala je na značajne razlike između tri lokaliteta što je
utjecalo na sastav biocenoza i pokrovnost makrofitima. Najveća brojnost zooplanktona i ženki s
jajašcima zabilježena je u eutrofnoj mrtvaji Škrčev kut, sa srednjom pokrovnošću flotantnim
makrofitima, dok je najmanja brojnost i raznolikost zooplanktona zabilježena u šljunčari Zajarki velike
prozirnosti i male trofije. Rukavac Sutle je odvojen u dva bazena: Gornji bazen veće prozirnosti i
pokrovnosti submerznim makrofitima, veće raznolikosti zooplanktona i izraženije predacije riba i Donji
bazen, veće mutnoće i bez makrofita, manje raznolikosti zooplanktona, a veliku brojnost postigle su
sitne detritivorne vrste kolnjaka i veslonožaca. Postaje na kojima je zabilježena najveća brojnost i
raznolikost zooplanktona nalazile su se u litoralnoj zoni čime je potvrđena uloga makrofita kao zaklona
od predacijskog pritiska. Na lokalitetu veće prozirnosti, šljunčari Zajarki, utvrđena je veća brojnost
zooplanktona, kao i ženki s jajašcima u pridnenom sloju vode, što potvrđuje da i u plitkim jezerima
postoje vertikalne, a ne isključivo horizontalne migracije. Na sva tri lokaliteta u zooplanktonu
dominirale su od Rotifera vrste roda Brachionus te vrste Kerratella cohlearis i Trichocerca similis, od
Copepoda vrsta Macrocyclops albidus i ličinački stadiji dok je kod Cladocera prevladavala vrsta
Bosmina longirostris.

Abstract (english)

The zooplankton research was conducted during the summer period of 2012 in three water bodies of
different origins, morphometry, trophic level, coverage and composition of macrophytes: on the back
water of the Sutla River, oxbow Škrčev kut and gravel pit Zajarki. The main hypotheses of this study
were: (i) width of macrophytes stands and their architecture significantly impact diversity and
abundance of zooplankton as well as fish predation; (ii) macrophyte stands affect the abiotic and biotic
factors of aquatic ecosystems. The research goals were to determine: 1) diversity and abundance of
zooplankton in lakes with submerged and floating macrophyte stands; 2) impact of fish predation on
composition and size structure of zooplankton in lakes with different stands of macrophytes; 3) impact
of macrophyte and fish predation on zooplankton fecundity.
The analysis of physico-chemical parameters showed statistically significant spatial differences between
three water bodies which affected the composition of the biocenoses and macrophytes coverage. The
highest abundance of zooplankton and females with eggs was recorded in eutrophic oxbow Škrčev kut,
with medium coverability of floating macrophytes, while the lowest abundance and diversity of
zooplankton was observed in the gravel pit Zajarki with high transparency and low trophic level. The
back water of Sutla River is separated in the Upper basin with higher transparency and macrophyte
coverage, higher zooplankton diversity and more pronounced fish predation, and in the Lower basin of
higher turbidity, without macrophytes, smaller diversity where detritivorous species of Rotifera and
Copepoda accomplished higher abundance. Stations that have recorded the higher abundance and
diversity of zooplankton were in the littoral zone, which confirmed the role of macrophytes as a shelter
from predation pressure. Fish predation affected on zooplankton and females with eggs horizontal
migration in the littoral zone with macrophytes or their vertical migration into the deeper water layers.
At all three locations in zooplankton composition dominated Rotifera with Kerratella cohlearis,
Trichocerca similis and Brachionus species, Copepoda with Macrocyclops albidus and larval stages
while in Cladocera dominated species was Bosmina longirostris.

• Keywords: predacijski pritisak; submerzni i flotantni makrofiti; zooplankton; Rotifera; Cladocera; Copepoda
• Keywords (english): predation pressure; submergent and floating macrophytes; zooplankton
• Language: croatian
• URN:NBN: urn:nbn:hr:217:605325
• Study programme: Title: Ecology; Study programme type: university; Study level: graduate; Academic / professional title: magistar/magistra ekologije i zaštite prirode (magistar/magistra ekologije i zaštite prirode)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2017-04-27 12:44:27