One way organic pollutants reach remote oceanic regions is by atmospheric transport. During the Malaspina-2010 expedition, across the Atlantic, Indian, and Pacific Oceans, we analyzed the polycyclic aromatic hydrocarbon (PAH) effects on oceanic microbial food webs. We performed perturbation experiments adding PAHs to classic dilution experiments. The phytoplankton growth rates were reduced by more than 5 times, being Prochlorococcus spp. the most affected. 62% of the experiments showed a reduction in the grazing rates due to the presence of PAHs. For the remaining experiments, grazing usually increased likely due to cascading effects. We identified changes in the slope of the relation between the growth rate and the dilution fraction induced by the pollutants, moving from no grazing to V-shape, or to negative slope, indicative of grazing increase by cascade effects and alterations of the grazers' activity structure. Our perturbation experiments indicate that PAHs could influence the structure oceanic food-webs structure.

Contamination of the marine environment by human-made plastic litter is a growing and global problem. Our study attempts to explain the presence of two plastic bottles beached on the Ouvéa Island, in the southwest Pacific Ocean, with trademarks from the Solomon Islands and Papua New Guinea (PNG). We simulate the oceanic drift tracks and associated transit times with a Lagrangian interpretation of the surface currents of a high-resolution ocean model. Our results show that it takes less than 2–3months for drifting objects to connect these archipelagos (New Caledonia, Solomon Islands and PNG) and highlight the role of the meridional component of the circulation rather than the dominant zonal jets. This study shows that the origin or traceability of trash represent valuable information that can be used to test and, ultimately, improve our understanding of ocean circulation.

A total of 24 stranded or bycatch cetaceans, including Balaenoptera omurai, Lagenodelphis hosei, Kogia sima, Stenella attenuata, Grampus griseus, Neophocaena phocaenoides, and Sousa chinensis, were collected from 2001 to 2011 in Taiwan. Using the muscular δ13C and δ15N data, three ecological groups were identified as the oceanic baleen whale, the neritic, and the coastal toothed whale groups, coinciding with their taxonomy, feeding habits and geographical distribution. A horizontal inshore to offshore distribution was found for the sympatric neritic toothed dolphins, G. griseus, K. sima, S. attenuata, and L. hosei in the outermost offshore waters, accompanying their growth. For the first time we identify Taiwan’s Chinese white dolphin, S. chinensis, as an exclusive fish eater. Cd and As bioaccumulated in the G. griseus, L. hosei and S. attenuata increase as they grow. Prey-derived As- and Cd-induced health threats were found in L. hosei, and G. griseus.

The main objective of this study is to apply artificial neural network (ANN) and wavelet-neural network (WNN) models for predicting a variety of ocean water quality parameters. In this regard, several water quality parameters in Hilo Bay, Pacific Ocean, are taken under consideration. Different combinations of water quality parameters are applied as input variables to predict daily values of salinity, temperature and DO as well as hourly values of DO. The results demonstrate that the WNN models are superior to the ANN models. Also, the hourly models developed for DO prediction outperform the daily models of DO. For the daily models, the most accurate model has R equal to 0.96, while for the hourly model it reaches up to 0.98. Overall, the results show the ability of the model to monitor the ocean parameters, in condition with missing data, or when regular measurement and monitoring are impossible.

Abundances and composition of marine litter and seabirds were estimated in the central South Pacific (SP) Ocean between the Chilean continental coast and the Easter Island Ecoregion. Litter was dominated by plastics throughout the study area, but the proportion of plastics was higher at sea and on the oceanic islands than in coastal waters and on continental beaches. Litter densities were higher close to the center of the SP subtropical gyre compared to the continental coast. The seabird assemblage was diverse (28 species), and several endemic species were recorded. Seabird abundances were higher in the coastal waters and around Juan Fernández Islands off the continental coast than in the Oceanic and Polynesian sectors. Endangered species breeding on Salas & Gómez Island were observed in the Polynesian sector, which suggests a high potential for negative interactions between seabirds and floating litter, both occurring in high densities in this sector.

Mercury and selenium were assessed in the sailfish, Istiophorus platypterus, from the Eastern Pacific. Sixty-seven individuals were sampled, muscle, liver, kidney, gonads and the prey found in the stomach contents were isolated during fishing 2011–2013 tournaments. Hg exhibited the following pattern (μgg−1 wet weight): liver (0.57±0.07)>muscle (0.56±0.04)>kidney (0.44±0.08)>gonad (0.14±0.01). The maximum concentration of Se was found in kidneys (14.1±1.9μgg−1), and the minimum in muscles (0.67±0.03μgg−1). High Se:Hg ratios were found for muscle (4.1±0.3), kidney (132.4±12.1), liver (54.0±4.4) and gonads (88.2±7.9); Hg:Se molar ratios were several orders of magnitude lower (muscle<0.4 and liver, kidney and gonad<0.03). Sailfish feed mainly on fishes and cephalopods with low Hg levels (<0.13μgg−1), these results indicate biomagnification of Hg and Se. The muscle of I. platypterus should be consumed (according the provisional tolerable weekly intake) by people cautiously so as not to exceed the recommended intake of 215g per week.