Ábrahám Levente: Biomonitoring a Dráva folyó magyarországi szakasza mentén 2000-2004 - Natura Somogyiensis 7. (Kaposvár, 2005)

Uherkovich, Ákos - Nógrádi, Sára: Middle-term changes in caddisfly (Trichoptera) communities of the Hungarian part of Drava river during the years 1992–2004 - Tegzes együttesek középtávú változásai a Dráva magyarországi szakasza mentén, 1992-2004 folyamán

UHERKOVICH Á. & NÓGRÁDI S.: CADDISFLIES (TRICHOPTERA) COMMUNITIES 53 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 Fig. 6.: The number of caddisflies of some important collecting sites in the Dráva region, 1992-2004 (Drávapalkonya: black, Vejti: grey and Drávasztára: white columns) 6. ábra: A tegzesek egyedszáma a Dráva mente néhány jelentékenyebb gyűjtőhelyén, 1992-2004 (Drávapalkonya: fekete, Vejti: szürke és Drávasztára: fehér oszlopok) Results Above all the series of data of Vízvár are evaluated. However, we also have to remark that this series of data is not uniform (see the previous chapter). Mostly the results of the years 1992, 1994 and 1998 were not satisfactory. Taking these facts into consideration we may ascertain as it follows: One of the most frequent species of these samples is Hydropsyche contubernalis McL. It is a widely distributed species all over the country, mostly along larger rivers. It is on wing from May throughout the summer and early autumn months, without characteristic maximum in its activity. At this site, Vízvár, the ratio oîH. contubernalis is relatively even, only one peak can be observed in the yearly activity (Fig. 7). All the Hydropsyche adults - containing all species of genus and also the indetermined females show a similar run (Fig. 8). Hydroptila sparsa Curt, and Psychomyia pusilla F. are also permanent and frequent member of caddisfly community of the river, and they are also frequent in all larger rivers, mostly in quicker, upper sections (Fig. 9). The activity of H. sparsa was on a low level in 1999-2000, but later it became more frequent again. P. pusilla, as the most dominant species of the community, has permanent high ratio among the caddisflies (Fig. 10). We cannot show their dominance in the years, when the collected material was unsatisfactory. The run of two leptocerids, Ceraclea dissmilis Steph. and Setodes punctatus F. are a little bit uneven. Although both species are frequent along larger and smaller rivers, and also along other types of waters, their hatching is not permanent but jerky. In very advantageous meteorological situation enormous mass of adults can hatch, thus these "peaks of activity" can disfigure the yearly activity (Figs. 11, 12). The third discussed leptocerid, Oecetis notata Ramb. (Fig. 13) shows a higher activity in the years 2001-2004. Indeed, this species was not frequent here earlier, but it was not only frequent but sometimes dominant along the lower section of Dráva in the early nineties, at Drávapalkonya and Drávasztára.