Annual phytoplankton production in a coastal lagoon of the southern California Current System

Abstract

Seasonal and annual integrated phytoplankton production (AIP) of a shallow lagoon of the NW coast of Baja California, Estero de Punta Banda, was estimated during inverse-estuarine con- ditions in 1998 and 1999, a non-El Nino year. Estero de Punta Banda is a coastal lagoon with no city/industrial waste input; its primary production is comparable to that of impacted coastal bodies such as those in the Southern California area. To calculate AIP, we used representative averages of chlorophyll a concentration for 2 regions within the lagoon (outer and inner), representative averages of the photosynthetic parameters, an atmospheric model to estimate photosynthetically available radiation (PAR), and multiple linear regression models for the vertical attenuation coefficient of PAR (K PAR) as a function of wind speed and tidal range. The seasonal average daily integrated primary production was highest in summer (880 and 47 mgC m -2 d -1 for the outer and inner regions, respec- tively), due to higher temperature and light levels, as is generally reported for other temperate estu- aries. Values in winter were about half those in summer. Average AIP for the whole lagoon (125 gC m -2 yr -1 ) was relatively low compared with estimates for larger, deeper and/or sewage- enriched coastal water bodies. This was mainly due to the shallow integration depth of AIP in our study area and to high turbidity caused by tidal currents and wind waves.