Accumulation and Effects of Dissolved and Nanoparticle Silver and Copper in Two Marine Seaweed Species

This study investigated the accumulation and effects of metal nanoparticles in two seaweed species, Ulva lactuca and Agardhiella subulata. Both seaweeds were exposed to silver nitrate (AgNO3), silver nanoparticles, and copper oxide (CuO) nanoparticles for 48 h. Metal accumulation occurred in both seaweed species in a concentration-dependent manner after 48 h exposure to each form of metal. In several cases, seaweeds exposed to AgNO3 (the dissolved form) accumulated comparatively higher tissue Ag concentration than seaweed exposed to Ag nanoparticles; and A. subulata had higher tissue Ag concentrations than U. lactuca after exposure to AgNO3 for 48 h. Additionally, clear differences were observed in the regulation of Ag between the two seaweed species. Photosynthetic toxicity (primarily due to decreased maximum electron transport rate) was observed in U. lactuca after exposure to AgNO3, Ag nanoparticles, and CuO nanoparticles. These results increase current knowledge about the differences in dissolved metal versus nanoparticle exposure in marine seaweeds and have implications in marine food webs

Influence of Water Hardness on Accumulation and Effects of Silver in the Green Alga, Raphidocelis subcapitata

Metal pollution from anthropogenic sources can pose a threat to aquatic systems. Silver is released into the environment from various industrial processes. In excess, silver can accumulate and cause adverse effects in aquatic organisms, particularly those in lower trophic levels, such as phytoplankton. Water chemistry parameters, such as hardness, have been shown to modify toxicity of metals because divalent cations compete with the metal for binding sites on the biological membrane. The objective of this study was to assess population growth and silver accumulation in the green alga, Raphidocelis subcapitata, after silver exposure in waters of varying hardness for 7 d. Throughout the exposure period, a decrease in algal cell density was observed with increasing silver concentrations. Silver accumulation in the algae decreased and cell density increased with increasing water hardness. Additionally, at least some degree of protection was observed against silver toxicity due to increased water hardness

The Influence of Acidification and Copper Exposure on Copper Accumulation and Anti-Oxidant Enzyme Responses in the Pond Snail, Lymnaea stagnalis

Atmospheric carbon dioxide is rising at an accelerated rated due to increased anthropogenic activities. Metals have also been a noted problem; however, little research has addressed combined exposure of both pollutants to sensitive, calcifying organisms in freshwater habitats. This study examined copper accumulation (over 7 d) and activity of the antioxidant enzymes, catalase and glutathione peroxidase (over 2 d), in the freshwater common pond snail, Lymnaea stagnalis, after exposure to ambient and increased (2000 µatm) CO2 and copper (control, 5, and 20 µg/L). Results demonstrated increased copper accumulation in soft tissue of snails exposed to copper; however, exposure to increased CO2 did not increase the magnitude of copper accumulation. After 2 d, increased glutathione peroxidase activity was observed in snails exposed to increased CO2 or copper individually; however, synergistic effects from exposure to both parameters were not observed. A greater response in glutathione peroxidase activity was observed in elevated CO2-exposed snails as compared to those exposed to copper. This study provides new insight into exposure to multiple contaminants, which elicit a similar compensatory response in L. stagnali

River Report. State of the Lower St. Johns River Basin, Florida: Water Quality, Fisheries, Aquatic Life, Contaminants, 2022.

https://digitalcommons.unf.edu/sotr/1012/thumbnail.jp

River Report. State of Lower St. JOhns River Basin, Florida: Water Quality, Fisheries, Aquatic Life, Contaminants, 2023

https://digitalcommons.unf.edu/sotr/1013/thumbnail.jp

Physiological responses of corals to ocean acidification and copper exposure

Acidification and land-based sources of pollution have been linked to widespread declines of coral cover in coastal reef ecosystems. In this study, two coral species, Acropora cervicornis and Pocillopora damicornis were exposed to increased copper at two CO2 levels for 96 h. Copper accumulation and anti-oxidant enzyme activities were measured. Copper accumulation only increased in A. cervicornis zooxanthellae and corresponded with photosynthetic toxicity. Enzyme activities in both coral species were affected; however, A. cervicornis was more sensitive than P. damicornis, and zooxanthellae were more affected than animal fractions of holobionts. Generally, activities of all anti-oxidant enzymes increased, with copper exposure in corals; whereas, activities of glutathione reductase and to some degree glutathione peroxidase were observed due to increasing CO2 exposure alone. Exposure to copper in combination with higher CO2 resulted in a synergistic response in some cases. These results provide insight into mechanisms of copper and CO2 impacts in corals. •Differences in copper accumulation and sensitivity were observed between coral species and between coral and zooxanthellae•Increased CO2 did not influence copper accumulation•Synergistic effects from combined CO2 and copper exposure were observed in corals•Altered enzyme activity was observed in both coral exposed to copper or CO2•A. cervicornis was more affected by copper and P. damicornis was more affected by increased CO

Analysis of Trace Element Concentrations and Antioxidant Enzyme Activity in Muscle Tissue of the Atlantic Sharpnose Shark, Rhizoprionodon terraenovae

Metals occur naturally in the environment; however, anthropogenic practices have greatly increased metal concentrations in waterways, sediments, and biota. Metals pose health risks to marine organisms and have been associated with oxidative stress, which can lead to protein denaturation, DNA mutations, and cellular apoptosis. Sharks are important species ecologically, recreationally, and commercially. Because they occupy a high trophic level, assessing muscle tissue metal concentrations in sharks may reflect metal transfer in marine food webs. In this study, concentrations of cadmium, copper, lead, nickel, selenium, silver, and zinc were measured in the muscle of Rhizoprionodon terraenovae (Atlantic sharpnose shark) from 12 sites along the coast of the southeastern United States. Activities of antioxidant enzymes (superoxide dismutase, catalase, glutathione peroxidase, and glutathione reductase) also were examined in the muscle tissue of R. terraenovae. A total of 165 samples were analyzed, and differences in trace element bioaccumulation and enzyme activity were observed across sites. R. terraenovae samples collected from South Florida and South Carolina had the highest cumulative trace element concentrations whereas those collected from North Carolina and Alabama had the lowest cumulative concentrations. Trace element concentrations in shark muscle tissue were significantly correlated to antioxidant enzyme activity, particularly with glutathione peroxidase, suggesting that this enzyme may serve as a non-lethal, biomarker of metal exposure in R. terraenovae. This is one of the most extensive studies providing reference levels of trace elements and oxidative stress enzymes in a single elasmobranch species within the U.S