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In recent years, dense Alexandrium ostenfeldii blooms have been reported in different coastal areas. In this study, we report for the first time the occurrence of A. ostenfeldii blooms associated with the detection of paralytic shellfish toxins (PSTs) in the Peruvian scallop (Argopecten purpuratus) from Paracas Bay. Alexandrium ostenfeldii blooms occurred at the end of summer and early fall, after the increase of riverine input and under stratified conditions following a decrease in wind velocity. The highest abundances occurred during warm sea surface temperatures (18–27 °C). High PST concentrations that exceed the maximum permissible level (800 μg STX eq. kg−1) occurred even under low A. ostenfeldii abundances (20 × 103 cells l−1). Our results contribute to a better understanding of the dynamics of A. ostenfeldii in coastal systems influenced by riverine inputs and upwelling and can be used to improve monitoring programs and allow the implementation of mitigation measures along the Peruvian coast. • Toxins in scallops and abundance of Alexandrium species abundances were studied. • River input and the decrease in wind velocity favored Alexandrium ostenfeldii blooms. • High toxin concentration was detected in low abundances of Alexandrium ostenfeldii. • The highest abundances of Alexandrium ostenfeldii occurred under warm temperatures. • Role of cyst in the development of blooms needs to be further investigated. [ABSTRACT FROM AUTHOR]

Bahía Independencia (Independence Bay) is a marine system whose structure and function, have been subject of various biological studies. From in situ assessment reports (IMARPE, DHN) and satellite data (QuikSCAT), variations in spatio-temporal hydrophysical conditions, based on winds, ocean circulation, temperature and salinity were described. For the analysis, descriptive statistics, correlation tests, multivariate analysis, analysis of variance (ANOVA) and maps with color scales were applied. Spatial distribution patterns whose formation is attributed to local factors were identified. On the surface there are latitudinal gradients of temperature and of salinity to a lesser extent, with higher values in the north of the bay, because of water drift due to wind stress and the influence of Laguna Grande, a semi-enclosed formation at the northern end of the Bay. Near the bottom level, in the north, temperature and salinity distributions reflect the upwelling circulation, evidenced by circulating water transversely to the long axis of the bay. Conversely, in the south, surface and near bottom circulations were coupled, determining clockwise and counter-clockwise fluxes, creating small areas with similar characteristics of salinity. The bay is normally intruded by upwelling Equatorial Subsurface Waters, and sometimes by mixed waters with Subtropical Surface Waters (ESSW). In the extreme 1997-98 El Niño the SSW occupied all the bay area. [ABSTRACT FROM AUTHOR]

Coastal hypoxia can occur naturally in inshore areas of the Eastern Boundary Upwelling Systems, influenced by the nutrient-rich and low-oxygen upwelling waters. This study aims to explore the influence of water stratification and winds on bottom-water hypoxia of the Paracas Bay, an area subjected to the most intense alongshore winds and active coastal upwelling in the Peruvian coast. Monitoring data of the Pisco-Paracas water properties (dissolved oxygen, temperature, salinity and estimated stratification), the Pisco River flow, and the intensities of surface winds of the outside upwelling area, and of the local area, were analysed for the period 2006 to 2015. Bottom waters deeper than 8 m in the bay were shown undergoing a hypoxic regime (oxygen <1.4 mL L−1) that becomes more frequent towards austral summer and less frequent towards winter. This seasonal difference was associated with changes in the oxygen content of incoming upwelling waters and changes in the intensity of both local and upwelling winds that drive the hydrodynamics of the bay. High frequency data analysis revealed that synoptic time-scale fluctuations of the upwelling-favourable and local winds modulate the intra-seasonal variability of hypoxia. Fluctuations of the former drive the inshore expansion of mixed and less hypoxic upwelling waters during June–September, whereas fluctuations of the latter during December–April drive the entrance and circulation of more hypoxic upwelling waters, and the development of stratification events that contribute to the persistence of bottom hypoxia. • The bottom waters of Paracas Bay can undergo persistent hypoxic conditions year round. • Synoptic wind fluctuations modulate intra-seasonal variability of hypoxia in the bay. • Water stratification follows wind fluctuations and modifies the hypoxic regime. [ABSTRACT FROM AUTHOR]

The Peruvian upwelling ecosystem has a high spatial and temporal variability in its primary production that could be inferred from in situ and satellite observations of chlorophyll. The differences between in situ (Clai) from IMARPE and satellite chlorophyll-a (Clas) from SeaWiFS data were studied using spatial and temporal coincident values, to know the relationship between Clai and Clas values from a simple linear regression model. Also, the goodness of fit between both observations during each season was calculated using the square root mean error. The hypothesis was that the Clas observations overestimated the Clai values and that in summer there is a better goodness of fit between Clai and Clas data, compared to other seasons. The general equation obtained relating both variables was: Clai = 0.9925 Clas 0.9055. The goodness of fit between both data sources with a log10 transformation was higher in spring (r = 0.84, RCME = 0.31) than in summer (r = 0.82, RCME = 0.33). The chlorophyll-a was overestimated in summer and fall, while it was underestimated in winter and spring by SeaWiFS satellite. [ABSTRACT FROM AUTHOR]