The spatial distribution of lentic water mite (Acari: Hydrachnidia) assemblages goverend by prey availability

Abstract

Vodengrinje su sekundarno akvatički predstavnici skupine grinja (Acari) koje možemo pronaći u svim tipovima slatkovodnih staništa. U fazi deutonimfa i odraslih jedinki gotovo sve vrste vodengrinja su predatori. Istraživanja o raspodjeli vodengrinja u ovisnosti o dostupnosti njihovog plijena u prirodnom okruženju su malobrojna, stoga je cilj ovog rada bio dokazati da je predacija najvažniji pokretač u sastavu i prostornoj raspodjeli zajednica vodengrinja. Unutar dvadeset i jedne akumulacije Dinaridske ekoregije Republike Hrvatske uzorkovan je zoobentos i mjerili fizikalno-kemijski parametri vode. Analizom podataka je utvrđeno da prostorna raspodjela vodengrinja u manjoj mjeri ovisi o okolišnim parametrima te o gradijentu dubine (zbog stabilnijih uvjeta u dubljim dijelovima). Najvećim dijelom je uvjetovana dostupnošću plijena: rašljoticalca (Cladocera), veslonošca (Copepoda), trzalaca (Chironomidae) i ljuskara (Ostracoda). Dostupnost plijena utvrđena je kao ključna varijabla koja upravlja sastavom i prostornom raspodjelom zajednica vodengrinja u lentičkim staništima.Water mites are a specific group of mites that have secondarily invaded freshwater habitats. Deutonymphs and adults of almost all species of water mites are predators. Studies of the distribution patterns and co-occurrence of water mites and their prey in littoral lentic habitats are not well known. Our main aim was to determine if predation was a significant driver in water mite assemblage composition and distribution. Samples of the zoobenthos and water physico-chemical parameters were taken from twenty-one man-made lakes in the Dinaric region of Croatia. Data analysis showed that the spatial distribution of water mites depended only partially on environmental parameters. There was also a positive correlation between water mite abundance and diversity and depth gradient (favoring more stable conditions in deeper parts of lakes). Water mite abundances were found to positively correlate with their prey of Cladocera, Copepoda, Chironomidae and Ostracoda. Predation was determined as a key biotic interaction, governing both spatial distribution and the composition of water mite assemblages