Factors associated with moderate blooms of Pyrodinium bahamense in shallow and restricted subtropical lagoons in the Gulf of California

Abstract

Abstract:We examined the environmental and biological factors related to blooms of the toxic dinoflagellate Pyrodinium bahamense in three shallow, restricted subtropical lagoons in the Gulf of California during the rainy summer. In the San Jos é , Yavaros, and El Colorado lagoons, the vegetative stage peaked at 63, 108, and 151 ( × 10 3 cells l -1), respectively. At San Jos é , production of cysts peaked at 9.7 × 10 3 g -1 of dry sediment mass as the bloom declined. Large diatoms predominated, with P. bahamense the most common dinoflagellate during the blooms. Abundance of P . bahamense at San Jos é was positively correlated with salinity (r = 0.50, p = 0.0003), seawater temperature (r = 0.44, p = 0.005), silicates (r = 0.45, p = 0.003), and ammonium (r = 0.32, p = 0.005), and negatively correlated with dissolved oxygen (r = -0.34, p < 0.0001). No such correlations were found at El Colorado and Yavaros. The environmental window that favors development of blooms is restricted to the summer and is influenced by seawater temperature, salinity, and relative concentrations of ammonium and phosphates that, in turn, depend on rainfall and runoff, which is greater on the eastern side of the Gulf where seawater quality is degraded.

Spatial and Temporal Variations in Pyrodinium bahamense Cyst Concentrations in the Sediments of Bioluminescent Mangrove Lagoon, St. Croix, USVI

“…High primary productivity is also supported by the relatively high sedimentary organic matter content in the eastern half compared to the western half of the lagoon as well as sedimentary C/N ratios between 10 and 20, typical of a mixed terrestrial-aquatic organic matter source (Meyers 1994). Based on these spatial variations in our data, we hypothesize that elevated nutrient availability, from terrestrial erosion or groundwater, is boosting phytoplankton primary productivity in the southern and eastern quadrants of the lagoon (Morquecho et al 2012;Usup et al 2012;Solero-Figueroa et al 2015). This increased productivity results in high rates of organic matter deposition, and subsequent decay of this sedimentary organic matter increases nutrient availability at the sediment-water interface for dinoflagellates to access during diurnal migrations through the water column (Zimberlin 2013).…”

“…However, recent declines in cyst abundance may be indicative of a declining P. bahamense population, possibly as a result of the formation of a sill at the mouth of the lagoon that is restricting water flow from the bay. While long water residence times have been proposed as important attributes of bioluminescent bays (Phlips et al 2006;Morquecho et al 2012), decreased water exchange is a mechanism that has been proposed as an explanation for the recent dimming of other bioluminescent bays and lagoons in the region (Alvarez 2014). Further, an open, free-flowing connection to a bay or the ocean has been recognized as a common attribute of all bioluminescent bays and lagoons (Seliger et al 1970).…”

“…Further studies suggest that P. bahamense may also be phosphorus rather than nitrogen limited, allowing them to develop a unique niche within ecosystems (Phlips et al 2002(Phlips et al , 2006. Why mangroves are important to P. bahamense growth is unclear, but may be related to the source of organic matter entering the system (Morquecho et al 2012;Soler-Figueroa et al 2015). For example, Usup et al (2012) found that in bays where P. bahamense blooms are common, more organic matter input from terrestrial sources, such as mangroves, occurred relative to marine sources such as sea grass.…”

Cyst morphology, germination characteristics, and potential toxicity of Pyrodinium bahamense in the Gulf of California

“…In contrast, extant cysts have a more limited distribution, generally in coastal areas with upwelling currents and estuaries, and confined mainly to tropical waters of the Atlantic, IndoWestern Pacific, and Western Europe (Usup and Azanza 1998). In Mexico, cysts of P. bahamense are found on both sides of the southern part of the Gulf of California (Byrne et al 1990, Martínez-Hernández and Hernández-Campos 1991, Helenes et al 2009, Limoges et al 2010, Morquecho et al 2012, in subtropical and tropical Pacific coastal areas (Limoges et al 2010), to the Gulf of Tehuantepec (Vásquez-Bedoya et al 2008, Limoges et al 2010, Sánchez-Cabeza et al 2012.…”

“…In lagoons of the southern Gulf of California, living cysts appear to be more prevalent when blooms decline at the end of summer. When there are no blooms, they may still germinate, but are unable to grow because adverse conditions prevail (Morquecho et al 2012).…”