Abstract
In recent years, the northwestern part of the North Pacific areas of Costa Rica has undergone rapid socioeconomic development. This situation, combined with the scarce available information about the water quality of the Gulf of Papagayo, became the starting point to carry out a study to investigate the spatiotemporal variations of physicochemical and biological parameters of surface waters. Seven samplings were collected during the dry season and the rainy season from October 2016 to February 2018. Water quality parameters such as: temperature, salinity, dissolved oxygen, and chlorophyll a of six analytes: nitrate, nitrite, ammonia, phosphate, silicate and biological oxygen demand were measured. The results showed that phosphate and ammonium levels were lower during the rainy season (<6 µg P-PO4−3 L−1–9.53 µg P-PO4−3 L−1 and <11 µg N-NH4+ L−1–9.57 µg N-NH4+ L−1) than during the dry season (<6 µg P-PO4−3 L−1–13.64 µg P-PO4−3 L−1 and <11 µg N-NH4+ L−1–14.43 µg N-NH4+ L−1), which may be related to low rainfall (0, 00–26, 16 mm) during the sampling period. The dry season showed enrichment of ammonium, phosphate, and chlorophyll a due to the influence of the coastal upwelling for the intensification of the Papagayo winds from December to March. The physical, chemical, and biological indicators demonstrated that the Gulf waters had adequate quality. Nonetheless, there are specific areas such as Culebra Bay with conditions that could show deterioration of water quality.
Highlights
IntroductionEcosystems can be altered, without appreciating the damage at first glance, due to the direct and indirect entry of polluting substances, such as nutrients that can limit or increase the production of an ecosystem [6]
The Gulf of Papagayo showed a decrease in temperature and an increase in salinity, with higher concentrations of chlorophyll a at the surface level
The drop in temperature and an increase in the concentration of chlorophyll a was due to the coastal outcrop produced by the intensification of the trade winds (Papagayo Wind Jet) that occurs during this time
Summary
Ecosystems can be altered, without appreciating the damage at first glance, due to the direct and indirect entry of polluting substances, such as nutrients that can limit or increase the production of an ecosystem [6] In this area, some studies have been carried out on the structure of the phytoplankton community [7], its marine biodiversity [8], the reefs [9], changes in the cover of mangroves [10], temperature, salinity, and dissolved oxygen [11], as well as aspects related to climate and subsurface temperature of the sea [12]. The goals of the research group were oceanographic characterization of the marine-coastal zone of the study area for the knowledge of the quality of its waters; understanding the spatial and temporal variations of the physicochemical parameters and chlorophyll a during the dry and rainy season; and providing the findings determined in the seventeen months of this study in this gulf that serve as a reference point for future water quality work in this region and in the areas of the tropical Pacific Ocean where there is a product outcrop of the winds
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