Meiofauna constitute a considerable portion of invertebrate drift among moss-rich patches within a karst hydrosystem

Abstract

Aiming to establish the most frequent invertebrate taxa in drift at the small spatial scale within a moss-rich karst tufa-precipitating hydrosystem, we sampled drift among microhabitats differing in substratum type and flow conditions along a tufa barrier-cascading lotic reach. Additionally, we addressed the question of the contribution and the potential significance of meiofauna within the overall invertebrate drift at the small spatial scale. During the study period, a total of 60 invertebrate taxa were recorded in the drift. Six of these taxa belonged to the annelid/arthropod meiofauna and they represented 35% of total drift density. Macroinvertebrates found in drift were represented mainly by larval insects. The composition of the most abundant taxa in total drift was as follows: Alona spp. (Cladocera 26.7%), Riolus spp. (Coleoptera: Elmidae 13.2%), Simulium spp. (Diptera: Simuliidae 12.2%), Enchytraeidae (Oligochaeta 10.4%), Hydrachnidia (6.3%), Orthocladinae (Diptera: Chironomidae 3.9%) and Naididae (Oligochaeta 3.6%). Faunal drift densities and amounts of transported particulate matter (PM) were highest at the fast-flowing sites located at the barriers and lowest at the slowflowing sites within pools. Similarly to the seasonal amounts of transported PM, faunal drift was lowest in winter, and peaked in autumn and in late spring/early summer. Correlation between flow velocity and PM-faunal drift densities suggested a significant effect of the dislodged PM, though a minor influence of discharge and flow velocity on faunal drift. We suggest that the small-scale habitat heterogeneity and the respective feeding and refugial strategies of the fauna, as well as faunal passive dislodgement initiated by the shear forces of the flow were the most important drivers of observed drift patterns.

Seiches in the Plitvice Lakes

“…Špoljar et al, 2007), organisms (e.g. Matoničkin Kepčija et al, 2011;Sertić Perić et al, 2014) and dead-leaf decomposition (Belančić et al, 2009).…”

Odonata drift: a reassessment

“…Reference number (individuals m -3 ) ODONATA Benke et al (1986) ( ≤ 0.06); Hornung (1982); Koetsier & Bryan (1995); March et al (2003); Muir (1990) 1 Not included are the density estimates given by Perić, Miliša, Kepčija, Primc-Habdija, and Habdija (2011) and Perić et al (2014), because their drift sampling was done in a unique setting (a moss-rich, karst, tufa-precipitating hydrosystem) and their density estimates were much higher than the highest estimates reported in other studies.…”

“…Bishop and Hynes (1969) reported that the few larvae of Zygoptera they captured in the drift were all less than 2 mm long -these had to have been early instars. Perić et al (2014) measured body lengths of Calopteryx spp. and Onychogomphus forcipatus larvae (avg.…”

The genus Dixa (Diptera, Dixidae) in Croatian lotic habitats, with a checklist of species and relationships with the fauna of neighbouring countries

“…Species diversity is highest in springs and in headwater streams (Wagner et al 2008). Dixid larvae are sometimes a significant component of invertebrate drift in streams (Elliott and Tullett 1977; Sertić Perić et al 2014). They are extremely sensitive indicators of the presence of surfactant or oil-borne pollutants in streams (Thomas 1979).…”