Predictive habitat suitability modeling of deep-sea framework-forming scleractinian corals in the Gulf of Mexico.

Framework-forming scleractinian (FFS) corals provide structurally complex habitats to support abundant and diverse benthic communities but are vulnerable to environmental changes and anthropogenic disturbances. Scientific modeling of suitable habitat provides important insights into the impact of the environmental conditions and fills the gap in the knowledge on habitat suitability. This study presents predictive habitat suitability modeling for deep-sea (depth > 50 m) FFS corals in the GoM. We first conducted a nonparametric estimate of the observed coral point process intensity as a function of each numeric environmental variable. Next, we performed species distribution modeling (SDM) using an assemble of four machine learning models - maximum entropy (ME), support vector machine (SVM), random forest (RF), and deep neural network (DNN). We found that most important variables controlling the coral distribution are super-dominant gravel and rock substrata, SW and SE aspects, slope steepness, salinity, depth, temperature, acidity, dissolved oxygen, and chlorophyll-a. Highly suitable habitats are predicted to be on the continental slope off Texas, Louisiana, and Mississippi and the shelf and slope of the West Florida Escarpment. All the four models have outstanding prediction performances with AUC values over 0.95. DNN model performs best (AUC = 0.987). The study contributes to coral habitat modeling research by presenting unique methods including nonparametric function of coral point process intensity, DNN and SVM models that have not been used in coral SDM, post-classification model assembling, and percentile approach to determine a threshold value for classifying a suitability score map into a binary map. Our findings would help support conservation prioritization, management and planning, and guide new field exploration.

Annual changes in concentrations and health risks of PCDD/Fs, DL-PCBs and organochlorine pesticides in ambient air based on the Global Monitoring Plan in São Paulo.

Ambient air contains a number of persistent organic pollutants (POPs), to which inhalation exposure has drawn worldwide concern. However, information regarding annual changes in the concentrations and health risks of POPs in the ambient air of São Paulo, Brazil, are limited. This study provides comprehensive information on annual changes in polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), dioxin-like polychlorinated biphenyls (DL-PCBs), and 10 groups of organochlorine pesticides (OCPs) in the ambient air of São Paulo between 2010 and 2015 based on the Global Monitoring Plan. The mass concentrations of the studied POPs (PCDD/Fs, DL-PCBs, and OCPs) showed declining trends from 2010 to 2015 (from 2.65 × 10-2 to 1.33 × 10-2 pg m-3, from 9.89 × 10-2 to 3.12 × 10-2 pg m-3, and from 0.313 to 0.100 ng m-3, respectively), which might be due to the decrease of non-intentional emissions. The carcinogenic risk (CR) and non-carcinogenic risk (Non-CR) of the studied POPs were 1.48 × 10-11 to 6.08 × 10-7 and 3.44 × 10-8 to 3.34 × 10-3, respectively, which are lower than the generally accepted threshold values (10-6/10-5 and 1 for CR and Non-CR, respectively), suggesting that the health risks posed by the studied POPs were acceptable. PCDD/Fs had the highest CR (6.08 × 10-8-4.81 × 10-7), whereas the 95th percentile CR of DL-PCBs and nine of the OCPs were lower than 10-7, suggesting that among the studied POPs, PCDD/Fs in the ambient air warrant special attention. The 95th percentile CRs of dichlorodiphenyltrichloroethane (2.30 × 10-8), dieldrin (1.30 × 10-8), hexachlorocyclohexanes (1.05 × 10-8), heptachlor (8.97 × 10-9), hexachlorobenzene (6.47 × 10-9), chlordane (5.89 × 10-9), heptachlor epoxide (1.42 × 10-9), aldrin (1.33 × 10-9), and mirex (2.71 × 10-10) in ambient air were relatively low, suggesting that their threats to human health were negligible. In general, PCDD/Fs, DL-PCBs, and OCPs in the ambient air of São Paulo did not pose serious threats to human health during 2010-2015.