Fry said:
Average oceanic salinity is about 35ppt (parts per thousand), so it would have been around 8.5 or 9 back then. Freshwater ranges from 0 - .5 ppt. Brackish water falls between freshwater and full ocean saltwater salinity.
Evolution Question???
- Thread starter ewurm
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Average oceanic salinity is about 35ppt (parts per thousand), so it would have been around 8.5 or 9 back then. Freshwater ranges from 0 - .5 ppt. Brackish water falls between freshwater and full ocean saltwater salinity.
How did the sea become salty?
Rain water falling on the land has a part in the weathering (breakdown) of rocks and the erosion (transport) of weathered rock fragments.
Rivers carry:
Larger rock fragments as bed load (rolling along the bottom of the stream),
Smaller rock fragments and mineral grains as suspended load (within the water column),
Ions or dissolved "salts" from the chemical weathering of rocks and minerals as dissolved load.
Feldspars are the most abundant minerals in the Earth's crust. Through a type of chemical weathering called hydrolysis, feldspars are altered to form clays, and their ions (Ca, K, and Na) are released to be carried in solution by running water, eventually making their way to the sea.
The weathering of other minerals and rocks also provides salts to the sea. For example, the calcite in limestone dissolves in slightly acidic natural waters, yielding Ca and CO3.
Rivers carry an estimated 4 billion tons of dissolved "salts" to the seas each year.
Some of these dissolved solids will be deposited as sediment, so yearly gains may roughly balance sediment deposition.
Salts have become concentrated in the sea (compared with freshwater) because the sun's heat causes the evaporation of water, leaving the salts behind.
The early sea's may have had a lowwer specific gravity but overall it's stable
Rain water falling on the land has a part in the weathering (breakdown) of rocks and the erosion (transport) of weathered rock fragments.
Rivers carry:
Larger rock fragments as bed load (rolling along the bottom of the stream),
Smaller rock fragments and mineral grains as suspended load (within the water column),
Ions or dissolved "salts" from the chemical weathering of rocks and minerals as dissolved load.
Feldspars are the most abundant minerals in the Earth's crust. Through a type of chemical weathering called hydrolysis, feldspars are altered to form clays, and their ions (Ca, K, and Na) are released to be carried in solution by running water, eventually making their way to the sea.
The weathering of other minerals and rocks also provides salts to the sea. For example, the calcite in limestone dissolves in slightly acidic natural waters, yielding Ca and CO3.
Rivers carry an estimated 4 billion tons of dissolved "salts" to the seas each year.
Some of these dissolved solids will be deposited as sediment, so yearly gains may roughly balance sediment deposition.
Salts have become concentrated in the sea (compared with freshwater) because the sun's heat causes the evaporation of water, leaving the salts behind.
The early sea's may have had a lowwer specific gravity but overall it's stable
concord said:firstly it takes thousands of years for a new species evolves
secondly look up on your evidence mate.
It was salt to fresh.
yup, and thousands may be underestimating, maybe more like tens of thousands depending on the reproductive rate of the species and change in the environment of course
Fry said:
The first fish in the ocean would have lived in water that had the salinity of what we would consider brackish today. There is an important difference though, brackish water is found at fresh/saltwater interfaces suchs as esturaies. The salinity in theses areas can fluctuate drasticly. In ocean enviroments the salinity changes little.
Alot of the hints to which came first has to do with fish nostrils. It is commonly believed that cichlids in particular started freshwater moved to saltwater then moved back to fresh most likely evolving from a damsel like saltwater species. The evidence I have seen points out that cichlids are the only family of fish that have a single pair of nostrils all other fish have 2 pair 1 for water in 1 for water out. Basically it is believed that cichlids are the most advanced of all fish because they have evolved to only have 1 pair of nostril. It is also thought that fresh and salt water fish evolved separately as well. One of the fish that are believed to start saltwater would be sharks which have been around a long time and not changed much.
So i guess the most likely answer would be "both"
So i guess the most likely answer would be "both"
The saltwater fish came first, then adapted to life without the salt ... just as we can do in the lab (e.g. freshwater clownfish, grouper, etc.) Saltwater fish are able to adapt to fresh, but it is impossible for fresh to adapt to salt.
I think god made all the fish in one day and evolutions a bunch of crap and all men were made in the lords image and I burn witches.......I am being sarcastic by the way!
