Quantification of floating ephippia in lakes: a step to a better understanding of high dispersal propensity of freshwater plankters

Abstract

Planktonic cladocerans of the genus Daphnia are an example of organisms whose ability to disperse among aquatic habitats is limited to dispersal of dormant eggs, encapsulated in protective structures called ephippia. In the present study, we aimed to quantify the production of floating and sinking ephippia in lakes to test the hypothesis that, even if they eventually sink, most of them are first floating at the surface. In addition, we checked the egg content status of the ephippia. The results of this study revealed numbers of ephippia floating at lakes surface reaching thousands per square metre at the time of ephippia production, and constituting substantial share of that production. In studied shallow lowland lakes and in a deep mountain lake, most ephippia were first floating at the water surface, while in deep lowland lakes the proportion was reversed. Approximately half of ephippia that appeared initially at the water surface sank during the six-week sampling period. The egg content status did not differ between floating and sinking ephippia. High numbers of ephippial females staying in the surface layers at night in a mountain lake, and a laboratory experiment with ephippial females indicated that ephippia are actively oviposited to the water surface by gravid females.

Spatial variability of aquatic plant and microfaunal seed and egg bank communities within a forested floodplain system of a temperate Australian river

“…size, floating capacity) were contributing factors for the spatial heterogeneity noted among the propagule bank communities. Future studies that quantitatively assess the role of propagule traits may assist in better understanding the relationship between hydrological conditions and dispersal capacity on the BMF floodplain (Cáceres et al 2007;Chambert and James 2009;Ś lusarczyk et al 2015).…”

Attachment and Release of Water Fleas’ Ephippia on a Medium-Sized Waterfowl’s Leg for Migration

“…The floatability of the ephippia is vital to their dispersal capacity. 2,3 The ephippium sizes and buoyancies vary with species. For example, Daphnia pulex usually has a considerable fraction of floating ephippia.…”

“…The ephippia from the females are released during molting and then sink to the bottom of lakes and ponds or float. The floatability of the ephippia is vital to their dispersal capacity. , The ephippium sizes and buoyancies vary with species. For example, Daphnia pulex usually has a considerable fraction of floating ephippia.…”