The first record of Elodea nuttallii (Hydrocharitaceae) in the Lower Dnipro River

Six localities of Elodea nuttallii were found in 2020 in the Lower Dnipro River (Kherson Region) within the territory of Nyzhniodniprovskyi National Nature Park. These are the first verified records of this alien aquatic plant (native to North America) in the Steppe Zone of Ukraine. Previously, it has been reported in Ukraine only from the Forest (Kyiv city) and Forest-Steppe (Kyiv, Poltava and Cherkasy administrative regions) zones. Geographic coordinates, depths and substrate are reported for all found localities. Geobotanical data about this species in Ukraine are summarized. It is assumed that Elodea nuttallii as a potentially invasive species in this region may occur not only in the Lower Dnipro River but also in all reservoirs on this river.

Snail communities improve submerged macrophytes growth by graze epiphytic algae and phytoplankton in a mesocosm experiment

The relationship between producers (e.g., macrophyte, phytoplankton and epiphytic algae) and snails plays an important role in maintaining the function and stability of the shallow ecosystems. A complex relationship exists among macrophytes, epiphytic algae, phytoplankton and snails. An outdoor mesocosm experiment with two-way factorials was carried out, three species submerged macrophytes (Hydrilla verticillate, Vallisneria natans or one exotic submerged plant Elodea nuttallii) and two grazing treatments (4 snail species present or absent) to elucidate those relationships. The results showed that the snail communities reducing the biomass of phytoplankton and epiphytic algae indirect then enhanced the growth of the submerged macrophytes. The macrophyte with complex architecture supported more snail and epiphytic algae, and snails preferred to feed on native plants. Competition drove snails change the grazing preferences to achieve coexistence, so that led to the assembling of snail communities towards the direction of highest resource utilization.

The early development of nodal adventitious roots with root hairs and root hair deformations by Elodea nuttallii (Planchon) H. St. Johns

Elodea nuttallii is a globally distributed aquatic vascular plant that provides many ecosystem services. In the sediment its roots fulfill important geochemical functions and initiate biological interactions within the rhizosphere. However, the macro-anatomy and development of its roots remained widely uncharacterized. This study aims to analyze the early morphogenesis of Elodeas roots and their general macro-anatomy. Therefore, plants free of roots were planted on two different sediment types and harvested along an individual time axis after the first roots were developed. All plants were photographed, measured and the roots were microscopically analyzed. Elodea has nodal adventitious roots, non-woody and from shoots. All roots have a root tip with a well-developed apical meristem and a root cap, an elongation zone, and a well-developed maturation zone with root hairs. Root hair deformations like swollen root hairs, swollen root hair tips, and branched root hairs most often developed when plants were grown on nutrient-poor, coarse-grained sediment. We here present a first description of the morpho- genesis and macro-anatomy of roots developed by E. nuttallii. This work will improve our understanding of this important species and foster further studies on the coupling between physiological processes, the morphogenesis, anatomy, ecosystem services, economical use, and management strategies related to E. nuttallii.

Adatok a Duna Komárom-Esztergom és Fejér megyei szakaszainak flórájához

A cikk elsősorban a Duna árterének vízi és iszapnövényzetével foglalkozik. Az adatok többnyire a 2019-es, tartósan alacsony vízállás mellett végzett felmérések eredményeit tükrözik. A Komárom-Esztergom megyei szakasz iszapnövényzete viszonylag jól kutatottnak számít, míg a Fejér megyei korábban alig volt ismert. A vizinövények közül a Gönyű és Neszmély közötti szakaszról korábban ismert, egyébként is ritka Hippuris vulgaris és Hydrocharis morsus-ranae nem került elő. Megjelent viszont több veszélyes özönnövény, így a Salvinia molesta, Myriophyllum aquaticum, Limnobium laevigatum, valamint a Crassula helmsii, melynek ez az első hazai adata. Hosszú évtizedek után ismét előkerült a Vallisneria spiralis, jelen van az Elodea canadensis, illetve egyre elterjedtebb az Elodea nuttallii és az Azolla taxonok. Az iszapnövényzetben új fajként jelent meg, sőt meglehetősen elterjedt lett a Lindernia procumbens és az adventív Lindernia dubia. Özönnövények közül megjelent a Cyperus esculentus, az Euphorbia maculata és az Eleusine indica. A korábban ismerthez képest jóval elterjedtebb lett a Veronica catenata és a Schoenoplectus triqueter, valamint nagyobb állományai vannak a Cyperus glomeratus-nak. A nyílt kavicsos felszínek érdekes növénye a több lelőhelyen is megtalált Polygonum graminifolium, melynek egészen a közelmúltig nem voltak aktuális hazai adatai.

Inorganic Mercury and Methyl-Mercury Uptake and Effects in the Aquatic Plant Elodea nuttallii: A Review of Multi-Omic Data in the Field and in Controlled Conditions

(1) Background: Mercury is a threat for the aquatic environment. Nonetheless, the entrance of Hg into food webs is not fully understood. Macrophytes are both central for Hg entry in food webs and are seen as good candidates for biomonitoring and bioremediation; (2) Methods: We review the knowledge gained on the uptake and effects of inorganic Hg (IHg) and methyl-Hg (MMHg) in the macrophyte Elodea nuttallii found in temperate freshwaters; (3) Results: E. nuttallii bioaccumulates IHg and MMHg, but IHg shows a higher affinity to cell walls. At the individual level, IHg reduced chlorophyll, while MMHg increased anthocyanin. Transcriptomics and metabolomics in shoots revealed that MMHg regulated a higher number of genes than IHg. Proteomics and metabolomics in cytosol revealed that IHg had more effect than MMHg; (4) Conclusions: MMHg and IHg show different cellular toxicity pathways. MMHg’s main impact appears on the non-soluble compartment, while IHg’s main impact happens on the soluble compartment. This is congruent with the higher affinity of IHg with dissolved OM (DOM) or cell walls. E. nuttallii is promising for biomonitoring, as its uptake and molecular responses reflect exposure to IHg and MMHg. More generally, multi-omics approaches identify cellular toxicity pathways and the early impact of sublethal pollution.