Identification and quantification of <i>Acanthamoeba</i> spp. within seawater at four coastal lagoons on the east coast of Australia

Acanthamoeba is an opportunistic free-living heterotrophic protist that is the most predominant amoeba in diverse ecological habitats. Acanthamoeba causes amoebic keratitis (AK), a painful and potentially blinding corneal infection. Major risk factors for AK have been linked to non-optimal contact lens hygiene practices and Acanthamoeba contamination of domestic and recreational water. This study investigated the incidence and seasonal variation of Acanthamoeba spp. within coastal lagoons located on the eastern coast of Australia and then examined the association between Acanthamoeba and water abiotic factors and bacterial species within the water.Water samples were collected from four intermittently closed and open lagoons (ICOLLs) (Wamberal, Terrigal, Avoca and Cockrone) every month between August 2019 to July 2020 except March and April. qPCR was used to target the Acanthamoeba 18S rRNA gene, validated by Sanger sequencing. Water abiotic factors were measured in situ using a multiprobe metre and 16S rRNA sequencing (V3-V4) was performed to characterise bacterial community composition. Network analysis was used to gauge putative associations between Acanthamoeba incidence and bacterial amplicon sequence variants (ASVs).Among 206 water samples analysed, 79 (38.3%) were Acanthamoeba positive and Acanthamoeba level was significantly higher in summer compared with winter, spring, or autumn (p = 0.008). More than 50% (23/45) water samples of Terrigal were positive for Acanthamoeba which is a highly urbanised area with extensive recreational activities while about 32% (16/49) samples were positive from Cockrone that is the least impacted lagoon by urban development. All sequenced strains belonged to the pathogenic genotype T4 clade except two which were of genotype clades T2 and T5. Water turbidity, temperature, intl1 gene concentration, and dissolved O2 were significantly associated with Acanthamoeba incidence (p &lt; 0.05). The ASVs level of cyanobacteria, Pseudomonas spp., Candidatus spp., and marine bacteria of the Actinobacteria phylum and Acanthamoeba 18S rRNA genes were positively correlated (Pearson's r ≥ 0.14). The presence of Acanthamoeba spp. in all lagoons, except Wamberal, was associated with significant differences in the composition of bacterial communities (beta diversity).The results of this study suggest that coastal lagoons, particularly those in urbanised regions with extensive water recreational activities, may pose an elevated risk to human health due to the relatively high incidence of pathogenic Acanthamoeba in the summer. These findings underscore the importance of educating the public about the rare yet devastating impact of AK on vision and quality of life, highlighting the need for collaborative efforts between public health officials and educators to promote awareness and preventive measures, especially focusing lagoons residents and travellers

Steam and Flame Applications as Novel Methods of Population Control for Invasive Asian Clam (Corbicula fluminea) and Zebra Mussel (Dreissena polymorpha)

Control strategies for established populations of invasive alien species can be costly and complex endeavours, which are frequently unsuccessful. Therefore, rapid-reaction techniques that are capable of maximising efficacy whilst minimising environmental damage are urgently required. The Asian clam (Corbicula fluminea Müller, 1774), and the zebra mussel (Dreissena polymorpha Pallas, 1771), are invaders capable of adversely affecting the functioning and biodiversity of freshwater ecosystems. Despite efforts to implement substantial population-control measures, both species continue to spread and persist within freshwater environments. As bivalve beds often become exposed during low-water conditions, this study examined the efficacy of steam-spray (≥100 °C, 350 kPa) and open-flame burn treatments (~1000 °C) to kill exposed individuals. Direct steam exposure lasting for 5 min caused 100% mortality of C. fluminea buried at a depth of 3 cm. Further, combined rake and thermal shock treatments, whereby the substrate is disturbed between each application of either a steam or open flame, caused 100% mortality of C. fluminea specimens residing within a 4-cm deep substrate patch, following three consecutive treatment applications. However, deeper 8-cm patches and water-saturated substrate reduced maximum bivalve species mortality rates to 77% and 70%, respectively. Finally, 100% of D. polymorpha specimens were killed following exposure to steam and open-flame treatments lasting for 30 s and 5 s, respectively. Overall, our results confirm the efficacy of thermal shock treatments as a potential tool for substantial control of low-water-exposed bivalves. Although promising, our results require validation through upscaling to field application, with consideration of other substrate types, increased substrate depth, greater bivalve densities, non-target and long-term treatment effects

Die Jemandssprache : Plädoyer für eine Deutsche Philologie unter besonderer Berücksichtigung von Heinrich von Morungen, Paul Celan und der "Auslandsgermanistik"

Der Titel „Jemandssprache“ bezieht sich kontrafaktisch auf Paul Celans Gedichtband „Die Niemandsrose“. (...) [In dem ersten Teil seine Aufsatzes bezieht sich Volker Mertens] auf die aktuelle Situation im Fach, in einem zweiten (...) [votiert er] für eine spezifische Gegenstandsbestimmung und einen bestimmten Umgang mit den methodischen Paradigmen, in einem dritten für eine Überwindung der Schwelle zwischen Älterer und Neuerer Literatur, (...), in einem vierten (...) [gibt er] eine vergleichende Interpretation je eines Gedichts von Heinrich von Morungen und von Paul Celan als Beispiel für eine Überschreitung der im Fach institutionalisierten Epochengrenze

Transport and fate of metal contamination in estuaries: Using a model network to predict the contributions of physical and chemical factors

Highlights: Power stations are a source of metal contaminants to nearby water bodies. Particle association is the main vector for transport of metals to bottom sediments. Network model successfully predicted metal distribution in sediments. Distance from point source alone cannot predict metal distribution. The particle density model was the main factor explaining particle movement.We thank NSW Office of Environment and Heritage for providing substantial field and logistical support. L. Schneider was financed by an International Postgraduate Research Scholarship (IPRS) funded by the Australian Government

Seagrasses in the South-East Australian Region - Distribution, Metabolism, and Morphology in Response to Hydrodynamic, Substrate, and Water Quality Stressors

This chapter describes the distribution of key seagrass species in the estuarine-nearshore coastal (ENC) continuum of the south-east region of Australia. We explore the potential influences of hydrodynamics (e.g. tidal currents, wave energy), estuary entrance dynamics (recruitment) and water quality, in addition to light, as primary stressors on seagrass processes and resilience. Despite primary controls exerted by light over seagrass distribution, there are significant areas of euphotic sediments in south-east region that are not colonised by seagrasses. In addition, seagrasses commonly display high degrees of inter-annual variability in coverage which cannot be explained solely by variations in light. We describe the main ecosystem types within the region, and demonstrate how the temporal and spatial gradients in hydrodynamic and water quality stressors (hence light climate), and the availability of suitable substrates for seagrass are controlled by the physical setting or geomorphology of the ecosystem. The opportunistic species Zostera muelleri is the most abundant species within the region, primarily occupying the highly dynamic estuarine niche. We provide a focus on Zostera muelleri to illus- trate the direct positive/negative impacts of hydrodynamic, water quality and estuary entrance morphology stressors on seagrass metabolism and morphology across light gradients