Browsing by Author "Duarte, Ricardo"
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- Common dolphin's shipping noise risk assessment on the Portuguese coastPublication . Spadoni, Giulia; Duarte, Ricardo; Soares, Cristiano; Fernandez, Marc; Jesus, SergioOcean noise generated by human activities at sea has been increasing over the decades, affecting marine eco systems. Ship traffic flow between the Mediterranean or South Atlantic and northern Europe makes the coast of Portugal one of the most intense shipping highways on a global scale. Among the cetaceans of the coast of Portugal, the common dolphin (Delphinus delphis) was selected as a target species. Based on 15 years of obser vations, the common dolphins' habitat suitability was estimated, together with the shipping noise maps for the year 2019, to produce seasonal risk maps for the same year. A large number of areas with a high noise risk index (≥0.85) were found in Portugal's southern and southwestern coasts, especially during the summer and fall seasons. Comparably, the 0.50 risk index exceeds 7 % and 3.5 % of the total area in summer and fall, respec tively. These percentages decrease to 1 % in spring and winter.
- A methodology for shipping noise field calibration and excess noise estimation: the Azores case studyPublication . Jesus, Sergio; Soares, Cristiano; Romagosa, Miriam; Cascão, Irma; Duarte, Ricardo; Zabel, Friedrich; Silva, Mónica A.Economic globalization and the continuous search for food, energy and raw materials led to an estimated 3 dB/decade increase of ocean noise intensity. Determining the level of anthropogenic noise, the so-called excess noise, and building identifiable meaningful indicators for supporting marine management policies currently requires extensive observation data and computer modeling. For modeling purposes, in this study, anthropogenic noise was reduced to shipping traffic drawn from Automatic Identification System data, and environmental sound was attributed to surface wind only. Data-model comparison allowed introducing a methodology for simple model calibration and estimate excess noise. This methodology was tested on acoustic recordings performed in June 2018 at three locations to the southwest of Faial-Pico Islands in the Azores archipelago. The results show that field-calibrated excess noise sound maps are in line with the shipping distribution in the area, revealing a number of potentially marine life-threatening hotspots. Excess noise addresses the need for a quantifiable measure of ocean noise only and therefore offers a basis for building suitable continuous anthropogenic noise pollution indicators.
- Shipping noise predictions from AIS in the Faial-Pico area, Azores archipelagoPublication . Soares, Cristiano; Duarte, Ricardo; Zabel, Friedrich; Silva, Monica A.; Jesus, SergioThe Azores archipelago, lying on the North Atlantic (NA) ocean, hosts one of the greatest diversities of cetaceans, and is an important habitat for several resident and migratory species. However, this unique diversity may be at risk due to the ocean noise generated by increasing commercial and recreational vessel traffic in the area. AIS shipping distribution and water column variability, together with suitable numerical propagation models were used to generate noise level maps for the area around Faial-Pico-Sao Jorge Islands, during June 2018. The generated noise level time-space distribution generally agrees with detected environmental variability and known navigation in the area, namely ferries between islands and fishing patterns.
- Soundscaping using a smart cable prototype off the coast of PortugalPublication . Duarte, Ricardo; Zabel, F.; Silva, António; Jesus, SergioOcean soundscaping is an important tool to monitor ocean noise and to understand how it may impact marine life. A promising approach is the exploration of the SMART cable concept that relies on the use of a telecommunication cable equipped with environmental sensors, allowing for ocean real-time monitoring. The K2D project(1) developed a set of cable nodes with extended SMART capabilities. These nodes were tested on a short telecommunication cable deployed off the coast of Sesimbra, Portugal. In this sea trial, several ocean variables were gathered, including underwater sound that was used to characterize the region's soundscape. Three types of analysis were conducted: a) the evaluation of the usual noise level baseline for all nodes, b) an attempt of sound source identification through frequency band analysis, and c) the evaluation of the noise level in different periods of the day. The results show that node 1 (the closest to shore) has higher noise levels and no significant difference between day and night periods in the frequency bands between 100 Hz and 1 kHz. No biological signatures were identified in the recorded data. Comparing the three nodes' locations, the results suggest that the area where node 1 was deployed is the most affected by (coastal) ship traffic.