The relationship between cupric ion activity and the toxicity of copper to phytoplankton

Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution April, 1975The purpose of this investigation is to quantify the relationship between cupric ion activity and the toxicity of copper to phytoplankton and further to study the effect on copper toxicity of naturally occurring organic ligands. Culture experiments with an estuarine diatom Thalassiosira pseudonana (clone 3H) in highly chelated seawater media demonstrated that copper induced growth rate inhibition and 3 to 4 day cellular uptake of copper are both related to the calculated free cupric ion activity and are independent of the total copper concentration. Cupric ion activity and total copper concentration were independently altered through various combinations of chelator (trishydroxymethyl amino methane) concentration, total copper concentration, and pH. Cellular copper content, in moles per cell, followed a hyperbolic relationship Cu/cell = 4.8 x 1-016 aCu/aCU + 10-9.2 where aCu is the free cupric ion activity. The above relationship suggests a reversible binding of copper to a single set of cellular ligand sites having a total binding capacity of 4.8 x 10-16 moles per cell and an association constant for reaction with copper of 109.2. For T. pseudonana (clone 3H) copper was inhibitory at pCu values below 10.7 (i.e. cupric ion activities above 10-10.7) with total growth inhibition occurring at pCu values below 8.3. The relationship between growth rate inhibition and cupric ion activity was not a simple hyperbolic relationship as was observed in the case of copper uptake. For an estuarine green alga Nannochloris atomus (clone GSB Nanno) and an open ocean strain of T. pseudonana (clone 13-1) partial growth rate inhibition occurred in the pCu ranges 10.3 to 8.4 and approximately 10 to 8, respectively. Comparison of these growth inhibitory pCu levels with a calculated estimate of the pCu of seawater of pH 8.2 containing a typica1 total copper concentration of 0.012 μM and having no significant copper chelation, indicates that natural cupric ion activity levels in seawater may be inhibitory to these three clones. Evidence was found for the complexation of copper by extracellular products of the alga T. pseudonana (clone 3H). Cupric ion selective electrode measurements of copper complexation in unused low salinity culture media and in identical media in which algae had been grown and from which they were subsequently filtered showed a higher degree of copper complexation in the used media. Parallel studies of copper toxicity and cellular copper uptake in an unused medium and in a culture filtrate demonstrated a lower copper toxicity and a decreased cellular copper uptake in the used medium. Cupric ion-selective electrode measurements and bioassay experiments support the hypothesis that copper is complexed by organic ligands in at least some natural waters. Copper added to filtered untreated river water is more highly complexed than that added to river water that has been uv irradiated to remove some portion of the dissolved organic matter. Copper toxicity to N. atomus is significantly increased in seawater from Vineyard Sound and in salt marsh water subjected to prior ultraviolet irradiation.This research was supported in part by Grant Numoer GB-33288 of the Biological Oceanography Section of the National Science Foundation, and in part by a Woods Hole Oceanograhic Institution Fellowship

The relationship between cupric ion activity and the toxicity of copper to phytoplankton

Culture experiments with the estuarine diatom Thalassiosira pseudonana (clone 3H) in highly chelated seawater media demonstrate that growth rate inhibition and copper content of cells are related to cupric ion activity, and not to total copper concentration. Cupric ion activity was altered independently of total copper concentration by varying the chelator concentration, and the pH...

The response of a marine bacterium to cupric ion and its use to estimate cupric ion activity in seawater

Experiments were conducted to determine the relationship between the response of a bacterial isolate to copper, as measured by cellular incorporation of 14C-glucose, and the complexation of copper by organic ligands. Inhibition of glucose incorporation was dependent on the cupric ion activity and independent of the concentration of organic complexes of copper both in UV-treated seawater (36‰) containing different concentrations of a model chelator, nitrilotriacetate (NTA), and in low salinity media (1.8‰) containing varied amounts of commercially-prepared or river-borne humic compounds...

The relationship between cupric ion activity and the toxicity of copper to phytoplankton

Thesis. 1975. Ph.D.--Massachusetts Institute of Technology. Dept. of Earth and Planetary Sciences.Bibliography: leaves 138-143.by William Sunda.Ph.D

Phytoplankton growth in nutrient rich seawater: Importance of copper-manganese cellular interactions

Matrix experiments were conducted to determine the role of trace metals in limiting phytoplankton growth rate in seawater collected from the deep nitrate maximum (800 m, 25 µM nitrate) off the North Carolina coast. Additions of FeCI3, MnCI2, and chelators (EDTA and NTA) stimulated the growth of unialgal cultures of Chaetoceros socialis or of a natural phytoplankton community inoculated into this seawater...

Increased toxicity of Karenia brevis during phosphate limited growth: ecological and evolutionary implications

Karenia brevis is the dominant toxic red tide algal species in the Gulf of Mexico. It produces potent neurotoxins (brevetoxins [PbTxs]), which negatively impact human and animal health, local economies, and ecosystem function. Field measurements have shown that cellular brevetoxin contents vary from 1–68 pg/cell but the source of this variability is uncertain. Increases in cellular toxicity caused by nutrient-limitation and inter-strain differences have been observed in many algal species. This study examined the effect of P-limitation of growth rate on cellular toxin concentrations in five Karenia brevis strains from different geographic locations. Phosphorous was selected because of evidence for regional P-limitation of algal growth in the Gulf of Mexico. Depending on the isolate, P-limited cells had 2.3- to 7.3-fold higher PbTx per cell than P-replete cells. The percent of cellular carbon associated with brevetoxins (%C-PbTx) was ~ 0.7 to 2.1% in P-replete cells, but increased to 1.6–5% under P-limitation. Because PbTxs are potent anti-grazing compounds, this increased investment in PbTxs should enhance cellular survival during periods of nutrient-limited growth. The %C-PbTx was inversely related to the specific growth rate in both the nutrient-replete and P-limited cultures of all strains. This inverse relationship is consistent with an evolutionary tradeoff between carbon investment in PbTxs and other grazing defenses, and C investment in growth and reproduction. In aquatic environments where nutrient supply and grazing pressure often vary on different temporal and spatial scales, this tradeoff would be selectively advantageous as it would result in increased net population growth rates. The variation in PbTx/cell values observed in this study can account for the range of values observed in the field, including the highest values, which are not observed under N-limitation. These results suggest P-limitation is an important factor regulating cellular toxicity and adverse impacts during at least some K. brevis blooms

MISSION ENGINEERING FOR HYBRID FORCE 2025

This report focuses on the mission engineering process for a hybrid force in 2025. Updated tasking from OPNAV N9I emphasized the necessity of focusing on the benefits of using cost-conservative unmanned systems. Specifically, the focus was placed on the near-peer competitor China and the problems that could be expected in an anti-access/area denial (A2/AD) situation in the South China Sea. The Naval Surface Warfare Center mission engineering approach was used to identify specific vignettes for proposed alternative fleet architectures and then analyzed using combat simulation and optimization models. Research on performance characteristics and cost were compiled on current unmanned systems, specifically those in development at a high technology readiness level. Proposed unmanned systems architectures were developed as solutions to the A2/AD problem and proposed vignettes. The unmanned systems architectures were then run through an optimization model to maximize system performance while minimizing cost. The results of the architecture optimization were then input into modeling and simulation. The overall effectiveness of each architecture in each vignette were then compared to find the most effective solution. An analysis of the results was performed to show the expected mission effectiveness and proposed cost of utilizing the proposed solution unmanned architectures. The most effective architectures included search, counter swarm, delivery, and attack systems.Lieutenant, United States NavyLieutenant, United States NavyLieutenant, United States NavyMajor, Republic of Singapore NavyMajor, Singapore ArmyLieutenant, United States NavyLieutenant, United States NavyLieutenant, United States NavyCommander, United States NavyApproved for public release. Distribution is unlimited

Insights Into the Biogeochemical Cycling of Iron, Nitrate, and Phosphate Across a 5,300 km South Pacific Zonal Section (153°E–150°W)

Iron, phosphate and nitrate are essential nutrients for phytoplankton growth and hence their supply into the surface ocean controls oceanic primary production. Here, we present a GEOTRACES zonal section (GP13; 30-33oS, 153oE-150oW) extending eastwards from Australia to the oligotrophic South Pacific Ocean gyre outlining the concentrations of these key nutrients. Surface dissolved iron concentrations are elevated at >0.4 nmol L-1 near continental Australia (west of 165°E) and decreased eastward to ≤0.2 nmol L-1 (170oW-150oW). The supply of dissolved iron into the upper ocean (<100m) from the atmosphere and vertical diffusivity averaged 11 ±10 nmol m-2 d-1. In the remote South Pacific Ocean (170oW-150oW) atmospherically sourced iron is a significant contributor to the surface dissolved iron pool with average supply contribution of 23 ± 17% (range 3% to 55%). Surface-water nitrate concentrations averaged 5 ±4 nmol L-1 between 170oW and 150oW whilst surface-water phosphate concentrations averaged 58 ±30 nmol L-1. The supply of nitrogen into the upper ocean is primarily from deeper waters (24-1647 μmol m-2 d-1) with atmospheric deposition and nitrogen fixation contributing <1% to the overall flux, in remote South Pacific waters. The deep water N:P ratio averaged 16 ±3 but declined to <1 above the deep chlorophyll maximum (DCM) indicating a high N:P assimilation ratio by phytoplankton leading to almost quantitative removal of nitrate. The supply stoichiometry for iron and nitrogen relative to phosphate at and above the DCM declines eastward leading to two biogeographical provinces: one with diazotroph production and the other without diazotroph production

Influence of CO2, nitrate, phosphate and silicate limitation on intracellular DMSP in batch cultures of the coastal diatom Thalassiosira pseudonana

International audienceWe measured intracellular DMSP concentrations in nutrient limited batch cultures of the coastal diatom Thalassiosira pseudonana. Under N, P, CO2, and Si growth limitation, intracellular DMSP concentrations decreased to low values during the exponential phase of growth and increased under nutrient limitation. The intracellular DMSP concentration increased exponentially with decreasing growth rate and cellular chlorophyll a, in response to the type and degree of nutrient limitation. For a given growth rate, N limited cells showed the greatest increase in cellular DMSP concentrations, CO2 and Si limitation had an intermediate effect, and P limitation caused the smallest increase. The results demonstrate the importance of nutrient limitation in enhancing DMSP concentrations in marine algae. This enhancement may be linked in part to the role of DMSP as a cellular antioxidant and to increased oxidative stress within cells during nutrient limitation. The replacement of DMSP, a sulfur containing osmolyte, for N containing osmolytes such as proline may also explain at least some of the DMSP increase under N limitation. Our results also point to the possible importance of diatom blooms in global or regional sulfur cycles