The effect of submarine groundwater discharge on nutrient and salinity regimes in a coastal lagoon off Perth, Western Australia

The Hillarys Transect (1): Seasonal and cross-shelf variability of physical and chemical water properties off Perth, Western Australia, 1996–98

“…Another potential source of freshwater is submarine groundwater discharge (SGD) which 558 contributes high-nutrient low-salinity water into the nearshore region of Marmion Lagoon (Johannes, 1980;Johannes and Hearn, 1985). Zaker et al (submitted) have also suggested that 560 SGD can play an important role in nearshore salinity variability especially during winter.…”

“…Zaker et al (submitted) have also suggested that 560 SGD can play an important role in nearshore salinity variability especially during winter. Johannes and Hearn (1985) measured nitrate concentrations of 400 µM in the freshest parts of 562 the discharge immediately off the beach, and found that reduced salinities (and correspondingly enhance nitrate concentrations) could extend out to 1.5 km from the shore under very calm 564 conditions although more generally the affected area was less than 300 m offshore. Station H0 was within about 100 m of the Marina breakwater, and it is therefore likely that SGD was 566 responsible for the reduced salinities at that station.…”

“…Another source of nearshore nutrients is submarine groundwater discharge (SGD, 834 mentioned above) which is extremely high in nitrate levels (Johannes, 1980;Johannes and Hearn, 1985) and may well be an important seasonal source of nutrients in Perth coastal waters, 836…”

Wave‐breaking hydrodynamics within coral reef systems and the effect of changing relative sea level

“…It focuses on coral reefs and uses as examples reefs that form coastal lagoons, but the analysis is applicable to any reef system, including limestone reefs. An example of the latter is the line of reefs along the west coast of Australia which were formed from old sand dunes by the holocene sea level rise, and these have well-defined lagoons [Johannes and Hearn, 1985]. Water circulation in all lagoons that lie behind reefs is driven by the same general forcing found in other shallow basins [e.g., Csanady, 1973], namely, wind [e.g., Frith and Mason, 1986], tide [Atkinson et al, 1981] and buoyancy [Hearn, 1996a].…”

Conference provides forum for discussion of subterranean coastal environments

“…The capacity of these systems to regenerate nutrients from POC also supports primary productivity at the sediment/water interface in shallow systems [Marinelli et al, 1998] and in the overlying water column.These systems are not limited to microbially mediated reac tions; they also support a range of ion exchange and weathering reactions.The significance of rates of all of these solid/dissolved phase reactions is indicated by a number of chemical enrichments in coastal systems that can eclipse river inputs in magnitude [Johannes and Hearn, 1985;Shum and Sundby, 1996;Moore, 1999;Marinelli et al, 1998;Krest et al, 2000;Huettel and Rusch, 2000] .The overall impact POC production and regeneration is not well known, but associated exports of DIC suggest there is an important contribution to the carbon budget in coastal systems [Shaw et al, 2000] .A growing body of evidence sug gests that a large range of physical environments supports subterranean coastal exchange, but much is yet to be learned about the range of diagenetic reactions supported by these systems and their regional and global impacts. Recent trends in many countries toward privatization and commercialization of datatwo distinct but linked issues-have become increasingly significant concerns for the geosciences and other scientific fields that need environmental data from around the world in order to study and understand Earth systems.…”