Environmental and ecological benefits and impacts of oyster aquaculture: Addendum

The data described in this addendum are provided to enhance the resolution and/or expand the temporal scope of the information already provided in the final report (Kellogg et al. 2018). High-resolution water quality transect data were collected at all four sites in Summer 2017, at White Stone (Windmill Point site) and Lynnhaven River in Fall 2017, and at White Stone (North Point site) in Spring 2018. During each sampling period, data were collected from multiple transects through and outside of each farm. Resulting data were detrended as needed based on temporal and salinity-related patterns found in data collected outside the farm footprint. Comparison of the resulting data from inside and outside the farm identified significant differences between water quality inside the farm footprint and outside for the majority of site x season combinations for all parameters. However, differences were consistently small enough to have no biologically significant impact, positive or negative, on farm-scale water quality. Benthic macrofaunal communities inside and outside the farms were assessed at White Stone’s Windmill Point site and at the Lynnhaven River site in Fall 2017 and White Stone’s North Point site in Spring 2018. Data on species richness, macrofauna abundance, and macrofauna biomass were compared between samples taken inside the farm footprint and outside the farm footprint for all site x season combinations. These data were compared to data previously reported from Summer 2017 collected at all four aquaculture sites. Overall, patterns in species richness and macrofauna abundance were not consistent across seasons within site, across sites within seasons or within gear type. With the exception of one of the farm sites studied, there was a trend towards increased macrofauna biomass inside the footprint of aquaculture farms. This pattern is consistent with the assumption that food for benthic macrofauna at these sites is enhanced by oyster biodeposition. Overall, we found no biologically significant negative impacts on macrofaunal communities inside aquaculture farms and some evidence that suggests a possible positive impact on benthic macrofauna production

A Data Repository for Minimal Effects of Oyster Aquaculture on Water Quality: Examples from Southern Chesapeake Bay

The objective of this study was to quantify the effects of oyster aquaculture on water quality, sediment quality, and hydrodynamics at select sites in southern Chesapeake Bay. To this end, information was gathered over the course of approximately one year from February 2017 to October 2017 at four operating commercial farms. Farms were sampled during spring, summer, and fall seasons during times of oyster filtration activity when temperatures were greater than 10oC. Aquaculture sites differed in environmental setting, in terms of their exposure to waves and resulting sediment characteristics. Sites had mesohaline salinities (ranging from 15-22 psu) and mean water depths of ~1 m (ranging from 0.5 to 2 m depending on distance from shore and tidal stage). Site characterization was conducted at each oyster farm using standard sedimentological measurements with a PONAR grab to map sediment characteristics throughout the extent of each oyster farm and surrounding area. Following site characterization, hydrographic, water clarity, and water quality data were collected using high frequency spatial water quality mapping of transects on a moving vessel and an instrumented profiler at discrete point samples. On high frequency spatial water quality mapping (transect) cruises, the vessel was driven along 10-30 transects including approximately half inside and half outside the extent of cages while vessel-mounted instruments sampled continuously. On discrete point sample (instrumented profiler) cruises, data were collected at five designated stations along a central transect of the farms with three stations within the extent of cages and two stations outside. The two smallest oyster farms were sampled only during Summer 2017. Two of the larger oyster farms were sampled during Summer and Fall 2017. Additionally, during Summer 2017 at Windmill Point, a stationary upward facing acoustic Doppler profiler collected data over one month

Minimal effects of oyster aquaculture on local water quality: Examples from southern Chesapeake Bay

As the oyster aquaculture industry grows and becomes incorporated into management practices, it is important to understand its effects on local environments. This study investigated how water quality and hydrodynamics varied among farms as well as inside versus outside the extent of caged grow-out areas located in southern Chesapeake Bay. Current speed and water quality variables (chlorophyll-a fluorescence, turbidity, and dissolved oxygen) were measured along multiple transects within and adjacent to four oyster farms during two seasons. At the scale of individual aquaculture sites, we were able to detect statistically significant differences in current speed and water quality variables between the areas inside and outside the farms. However, the magnitudes of the water quality differences were minor. Differences between sites and between seasons for water quality variables were typically an order of magnitude greater than those observed within each site (i.e. inside and outside the farm footprint). The relatively small effect of the presence of oysters on water quality is likely attributable to a combination of high background variability, relatively high flushing rates, relatively low oyster density, and small farm footprints. Minimal impacts overall suggest that low-density oyster farms located in adequately-flushed areas are unlikely to negatively impact local water quality. Associated datafiles available at: https://doi.org/10.25773/wwva-tz1

Diatoms Reduce Decomposition of and Fungal Abundance on Less Recalcitrant Leaf Litter via Negative Priming

Heterotrophic microbial decomposers colonize submerged leaf litter in close spatial proximity to periphytic algae that exude labile organic carbon during photosynthesis. These exudates are conjectured to affect microbial decomposers' abundance, resulting in a stimulated (positive priming) or reduced (negative priming) leaf litter decomposition. Yet, the occurrence, direction, and intensity of priming associated with leaf material of differing recalcitrance remains poorly tested. To assess priming, we submerged leaf litter of differing recalcitrance (Alnus glutinosa [alder; less recalcitrant] and Fagus sylvatica [beech; more recalcitrant]) in microcosms and quantified bacterial, fungal, and diatom abundance as well as leaf litter decomposition over 30 days in absence and presence of light. Diatoms did not affect beech decomposition but reduced alder decomposition by 20% and alder-associated fungal abundance by 40% in the treatments including all microbial groups and light, thus showing negative priming. These results suggest that alder-associated heterotrophs acquired energy from diatom exudates rather than from leaf litter. Moreover, it is suggested that these heterotrophs have channeled energy to alternative (reproductive) pathways that may modify energy and nutrient availability for the remaining food web and result in carbon pools protected from decomposition in light-exposed stream sections

Reduction of Pesticide Toxicity Under Field-Relevant Conditions? The Interaction of Titanium Dioxide Nanoparticles, Ultraviolet, and Natural Organic Matter

In surface waters, the illumination of photoactive engineered nanomaterials (ENMs) with ultraviolet (UV) light triggers the formation of reactive intermediates, consequently altering the ecotoxicological potential of co-occurring organic micropollutants including pesticides due to catalytic degradation. Simultaneously, omnipresent natural organic matter (NOM) adsorbs onto ENM surfaces, altering the ENM surface properties. Also, NOM absorbs light, reducing the photo(cata)lytic transformation of pesticides. Interactions between these environmental factors impact 1) directly the ecotoxicity of photoactive ENMs, and 2) indirectly the degradation of pesticides. We assessed the impact of field-relevant UV radiation (up to 2.6 W UVA/m(2)), NOM (4 mg TOC/L), and photoactive ENM (nTiO(2), 50 mu g/L) on the acute toxicity of 6 pesticides inDaphnia magna. We selected azoxystrobin, dimethoate, malathion, parathion, permethrin, and pirimicarb because of their varying photo- and hydrolytic stabilities. Increasing UVA alone partially reduced pesticide toxicity, seemingly due to enhanced degradation. Even at 50 mu g/L, nano-sized titanium dioxide (nTiO(2)) reduced but also increased pesticide toxicity (depending on the applied pesticide), which is attributable to 1) more efficient degradation and potentially 2) photocatalytically induced formation of toxic by-products. Natural organic matter 1) partially reduced pesticide toxicity, not evidently accompanied by enhanced pesticide degradation, but also 2) inhibited pesticide degradation, effectively increasing the pesticide toxicity. Predicting the ecotoxicological potential of pesticides based on their interaction with UV light or interaction with NOM was hardly possible, which was even more difficult in the presence of nTiO(2). (c) 2020 The Authors.Environmental Toxicology and Chemistrypublished by Wiley Periodicals LLC on behalf of SETAC

Characterization and applications of nanoparticles modified in-flight with silica or silica-organic coatings

Nanoparticles are coated in-flight with a plasma-enhanced chemical vapor deposition (PECVD) process at ambient or elevated temperatures (up to 300 °C). Two silicon precursors, tetraethyl orthosilicate (TEOS) and hexamethyldisiloxane (HMDSO), are used to produce inorganic silica or silica-organic shells on Pt, Au and TiO2 particles. The morphology of the coated particles is examined with transmission electron microscopy (TEM) and the chemical composition is studied with Fourier-transform infrared spectroscopy (FTIR), Energy-dispersive X-ray spectroscopy (EDX) and X-ray photoelectron spectroscopy (XPS). It is found that both the precursor and certain core materials have an influence on the coating composition, while other parameters, such as the precursor concentration, aerosol residence time and temperature, influence the morphology, but hardly the chemical composition. The coated particles are used to demonstrate simple applications, such as the modification of the surface wettability of powders and the improvement or hampering of the photocatalytic activity of titania particles

Consequences of pharmacophagous uptake from plants and conspecifics in a sawfly elucidated using chemical and molecular techniques

Paul SC, Dennis AB, Tewes L-J, Friedrichs J, Müller C. Consequences of pharmacophagous uptake from plants and conspecifics in a sawfly elucidated using chemical and molecular techniques. bioRxiv. 2021.Pharmacophagy involves the sequestration of specialised plant metabolites for non-nutritive purposes and commonly occurs in insects. Here we investigate pharmacophagy in the turnip sawfly, Athalia rosae, where adults not only collect specialised metabolites (clerodanoids) from a plant (Ajuga reptans), but also from the exterior of conspecifics via fighting. Using behavioural assays, chemical analytics, and RNAseq we show that when individuals nibble on conspecifics that have already acquired clerodanoids from A. reptans leaves, this nibbling results in the transfer of compounds between individuals. Furthermore, unlike other pharmacophagous insects, the acquisition of clerodanoids by A. rosae from the leaves of A. reptans does not induce the upregulation of known detoxification or sequestration genes and pathways. In contrast, pharmacophagous nibbling on conspecifics results in the upregulation of metabolic pathways associated with elevated metabolic rates and increased energy consumption. It therefore seems that individuals attack conspecifics to acquire clerodanoids despite the apparent metabolic costs of this form of pharmacophagy compared to clerodanoid uptake from a plant. Changes in the metabolic phenotype of A.rosae individuals consequently has profound consequences for social interactions with possible ramifications for their social niche