Temperature Effects Explain Continental Scale Distribution of Cyanobacterial Toxins

Insight into how environmental change determines the production and distribution of cyanobacterial toxins is necessary for risk assessment. Management guidelines currently focus on hepatotoxins (microcystins). Increasing attention is given to other classes, such as neurotoxins (e.g., anatoxin-a) and cytotoxins (e.g., cylindrospermopsin) due to their potency. Most studies examine the relationship between individual toxin variants and environmental factors, such as nutrients, temperature and light. In summer 2015, we collected samples across Europe to investigate the effect of nutrient and temperature gradients on the variability of toxin production at a continental scale. Direct and indirect effects of temperature were the main drivers of the spatial distribution in the toxins produced by the cyanobacterial community, the toxin concentrations and toxin quota. Generalized linear models showed that a Toxin Diversity Index (TDI) increased with latitude, while it decreased with water stability. Increases in TDI were explained through a significant increase in toxin variants such as MC-YR, anatoxin and cylindrospermopsin, accompanied by a decreasing presence of MC-LR. While global warming continues, the direct and indirect effects of increased lake temperatures will drive changes in the distribution of cyanobacterial toxins in Europe, potentially promoting selection of a few highly toxic species or strains.Peer reviewe

ASSESSMENT OF TEMPORAL ECOSYSTEM RESPONSES TO PHYTOPLANKTONS VIA PHOTOSYNTHETIC PIGMENTS UNDER A POTENTIAL OIL SPILL EVENT IN ISKENDERUN BAY

Ecosystem risk assessments after oil spills need at least one biological component's response to have some degree of understanding of the risks associated with the spill. In this study, crude oil spill impacts were studied under a spill scenario in Iskenderun Bay, which is a highly prone area to oil tanker accidents due to the high levels of transpassing. The study evaluated phytoplankton communities' response in 4 different seasons. Photosynthetic pigments data, obtained by HPLC, was used to assess community shifts of phytoplankton under different doses of the crude oil. It was found that the time of year of incidence is critical to understanding the consequences because a highly significant response difference was detected, which is more than an order of magnitude between winter and fall seasons. Due to physical conditions of seawater and initial phytoplankton compositions, the ecosystem showed more tolerance to the crude oil in winter than other seasons. EC50 values varied between 11.5 and 122.3 mu g/L total petroleum hydrocarbon (TPH) concentrations for all seasons. It is shown that the time of the year and known TPH concentrations of the seawater can possibly tell us about the potential impact of an oil spill in this region

İskenderun Körfezinde Olası Bir Petrol Tankeri Kazasında Doğabilecek Ekosistem Tepkilerinin Fitoplankton Düzeyinde Değerlendirilmesi

Deniz ekosisteminde petrol kazaları riskinin yaratabileceği olumsuz durumların değerlendirilmesinde en az bir tane biyolojik yapının buna vermiş olduğu tepkinin bilinmesi, oluşabileck riskin anlaşılmasında bize yardımcı olacaktır. Bu çalışmada tanker trafiğinin yoğunluğundan dolayı tanker kazasına hayli açık olan İskenderun Körfezinde olabilecek bir kazada oluşabilecek ekosistem etkileri çalışılmıştır. Dört farklı mevsimde ham petrole maruz bırakılan fitoplankton komünitelerinde oluşan değişimler, farklı ham petrol konsantrasyonları altında değerlendirilmiştir. Fotosentetik pigment verileri HPLC yardımıyla toplanmış ve fitoplankton komünite değişimleri bu verilere dayanarak değerlendirilmiştir. Bu çalışmadan çıkan sonuçlara göre, fitoplankton komünitelerinin ham petrole vermiş olduğu tepki mevsimlere göre çok farklılık göstermektedir. Örneğin kış ve sonbahar arasında yaklaşık 10 katlık bir fark oluşturmaktadır. Denizin fiziksel durumu ve ilk fitoplankton kompozisyonunun farklılığından kaynaklı olarak kış mevsimi fitoplanktonların ham petrole karşı en fazla tolerans gösterdiği mevsim olarak belirlenmiştir. EC50 değerleri toplam petrol hidrokarbonu (TPH) cinsinden 11.5 - 122.3 µg/L arasında mevsimsel farklılıklar göstermiştir. Bu sonuçlar; olası tanker kazasından sonra o bölgede oluşacak ekosistem etkilerinin değerlendirilmesinde, kazanın oluşacağı mevsimin ve deniz suyunda oluşacak TPH konsantrasyonun bilinmesi bize yardımcı olabileceğini göstermektedir

Assessment of temporal ecosystem responses to phytoplankton via photosynthetic pigments under a potential oil spill event in Iskenderun bay

Ecosystem risk assessments after oil spills need at least one biological component's response to have some degree of understanding of the risks associated with the spill. In this study, crude oil spill impacts were studied under a spill scenario in Iskenderun Bay, which is a highly prone area to oil tanker accidents due to the high levels of transpassing. The study evaluated phytoplankton communities' response in 4 different seasons. Photosynthetic pigments data, obtained by HPLC, was used to assess community shifts of phytoplankton under different doses of the crude oil. It was found that the time of year of incidence is critical to understanding the consequences because a highly significant response difference was detected, which is more than an order of magnitude between winter and fall seasons. Due to physical conditions of seawater and initial phytoplankton compositions, the ecosystem showed more tolerance to the crude oil in winter than other seasons. EC50 values varied between 11.5 and 122.3 mu g/L total petroleum hydrocarbon (TPH) concentrations for all seasons. It is shown that the time of the year and known TPH concentrations of the seawater can possibly tell us about the potential impact of an oil spill in this region

Can Crude Oil Toxicity on Phytoplankton Be Predicted Based on Toxicity Data on Benzo(a)Pyrene and Naphthalene?

Polycyclic aromatic hydrocarbons (PAHs), which are major components of crude oil, are responsible in large part for the toxicity of crude oil to phytoplankton. This study addressed the following question. Can reliable predictions of the aquatic toxicity of crude oil, a multi-component mixture, be described from toxicity data on individual PAH compounds? Naphthalene, the most abundant PAH compound, and benzo(a)pyrene, a highly toxic PAH compound, were selected as model compounds to quantify toxicity of crude oil on two phytoplankton species, Ditylum brightwellii and Heterocapsa triquetra, by analyzing the effects of different concentrations of these PAHs on growth rate. EC50 values suggested that the diatom D. brightwellii was more vulnerable to both toxicants than the dinoflagellate H. triquetra. However, a previous study, which investigated the impact of crude oil on the same two species, had opposite results. The differences in response from these phytoplankton species to naphthalene and benzo(a)pyrene toxicity compared to their response to crude oil suggest that they may not be solely used as surrogates to assess crude oil toxicity on phytoplankton

Degradation of Bisphenol A in Natural and Artificial Marine and Freshwaters in Turkey

Bisphenol A (BPA), one of the important synthetic chemicals, has been produced at high volumes since the 1960s. These chemicals are commonly detected in the marine and freshwater environments; however, their transformation in aquatic environments depends on many parameters. This study aims to investigate the degradation of BPA in marine and freshwaters under different conditions in terms of microbial degradation, photodegradation, and temperature effect. The results showed that BPA content in samples prepared from the artificial waters did not change significantly in 150 days. BPA concentrations in natural river water started to degrade after day 50, and the degradation rate was faster for the samples at 25 degrees C than ones at 4 degrees C. In natural seawater samples, there was no degradation detected in 150 days at 4 degrees C and 25 degrees C. However, samples prepared in natural seawater, kept outside, and exposed to over 40 degrees C temperature showed degradation after day 50. A treatment exposed to the sunlight showed a higher degradation rate, indicating the additive/synergistic role of the photodegradation. Our study suggests that high temperatures ( > 25 degrees C) are required for BPA degradation in seawater. River water is more potent than seawater for BPA degradation. It is suggested that BPA contamination in a marine environment could be more persistent than in a freshwater environment

Temporal and Spatial Distributions of Bisphenol A in Marine and Freshwaters in Turkey

Bisphenol A (BPA), a chemical component used in the manufacture of plastics, is commonly introduced to and detected in aquatic environments. This is the first study conducted to understand the distribution of BPA in the marine and freshwaters of Turkey. The purpose of this study is to report BPA concentrations measured from a time-series conducted in coastal waters of Erdemli and regional rivers located in the northeastern Mediterranean region. Furthermore, seawater samples obtained from other Turkish coastal areasThe Black Sea, Bosphorus, Sea of Marmara, and the Mediterranean Seaalso were investigated to gain a better understanding of regional and seasonal variations of BPA concentrations in Turkish Seas. Whilst spatial variation in BPA concentrations was very low, temporal variation was found to be high. It has been shown that BPA can reach the deep sea environment (>500m depth). This study indicated that BPA contamination has reached serious levels at another location in the world

Distinct responses of Gulf of Mexico phytoplankton communities to crude oil and the dispersant corexit(A (R)) Ec9500A under different nutrient regimes

This study examines the potential effects of exposure to South Louisiana sweet crude oil (LSC), Corexit(A (R)) EC9500A, and dispersed oil on enclosed phytoplankton communities under different nutrient regimes. Three distinct microcosm experiments were conducted for 10 days to assess changes to the structure of natural communities from the Gulf of Mexico as quantified by temporal changes in the biomasses of different phytoplankton groups. Concentration of NO3, Si and PO4 were 0.83, 0.99 and 0.09 mu M for the unenriched treatments and 14.07, 13.01 and 0.94 mu M for the enriched treatments, respectively. Overall, the contaminants LSC and Corexit(A (R)) EC9500A led to a decrease in the number of sensitive species and an increase in more resistant species. Phytoplankton communities showed more sensitivity to LSC under nutrient-limited conditions. The addition of nutrients to initially nutrient-limited treatments lessened the inhibitory effect of LSC in the short term. Centric diatoms benefited most from this enrichment, but pennate diatoms demonstrated considerably greater tolerance to crude oil at low crude oil concentrations in nutrient-enriched treatments. Dinoflagellates showed relatively higher tolerance in nutrient-limited treatments and high crude oil concentrations. Corexit(A (R)) EC9500A inputs significantly increased the toxicity of crude oil. Corexit(A (R)) EC9500A alone had a highly inhibitory effect at 63 ppm on phytoplankton communities. This study highlights the fact that different nutrient regimes play a major role in determining the shifts of the phytoplankton community in response to exposure to different concentrations of crude oil and dispersant. Determination of the functional equivalence of shifted phytoplankton groups could complement our research and allow for more pertinent extrapolation to real world conditions