. The Canadian field-naturalist. Natural history; Sciences naturelles. 2005 LONDRY, BADIOU, AND GRASBY: IDENTIFICATION OF A MARINE GREEN ALGA 83 0 100 km 1:3,000,000 # saline spring O spring with extensive mat development â fr spring with Percursaria percursa confirmed. Figure 1. Regional map showing locations of saline springs, indicating which ones have been observed to have microbial mats of P. percursa. and limits growth in these areas, ranges from below seawater to twice seawater concentrations. The salinity is mostly from NaCl (from halite), with minor differ- ences in composition compar
. The Canadian field-naturalist. Natural history; Sciences naturelles. 2005 LONDRY, BADIOU, AND GRASBY: IDENTIFICATION OF A MARINE GREEN ALGA 83 0 100 km 1:3,000,000 # saline spring O spring with extensive mat development â fr spring with Percursaria percursa confirmed. Figure 1. Regional map showing locations of saline springs, indicating which ones have been observed to have microbial mats of P. percursa. and limits growth in these areas, ranges from below seawater to twice seawater concentrations. The salinity is mostly from NaCl (from halite), with minor differ- ences in composition compared to typical seawater. The salt from these springs has been used historically by early settlers (Petch 1987). Chloride and sulfate concentrations in springs containing microbial mats are typically 24 to 36 g/1 and to g/1, respectively (Table 1). Gas bubbles rising from the spring sediments were observed frequently, often becoming trapped by the overlying mat in springs with confluent growth, leading to the appearance of medium to large swellings of the mat fabric. The gas composition is dominantly N, (95%) with traces of C02 (), He (), O, (), Ar (), and CH4 () (McKillop et al. 1992), with the latter two potentially supporting micro- bial growth. Each site consisted of multiple spring outlets, most of which formed pools around the origin, the oldest of which have formed raised cauldrons. Microbial mats grew on the surface and around the margins of the pools (Figure 2). There was considerable red goethite (FeOOH) staining in areas surrounding the springs, but not in the spring sources themselves, which are dominated by calcite and quartz. Areas surrounding the springs also sometimes exhibited a characteristic "brainy" texture due to the decomposition of the algal mats beneath the evaporitic gypsum crust. The springs flow year-round and the salinity keeps some of the larger ones from freezing, even in winter (McKillops et al. 1992). Microbi
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