It was cold when we arrived in the Sahara. The wind was blowing hard from the north as we got the plane. “We” were a group of 7 scientists, 3 professors from King Mohammed V University and its Institut Scientifique, two from Belgium, one from the College of Charleston, and me. We were here to study a series of desert salt ponds, termed sebkhas in this part of the world. Mostly the group consisted biologists who were interested in the fish that live in these salt pools, the parasites that live in the fish, and a few of the other creepy crawling things that inhabit these sparse and salty pools of water. I came along as the group’s geologist- I was interested in where the water came from, and why these places are so salty.
We were based in Dakhla- a small city along a peninsula in Morocco’s coastal Sahara. Dakhla is about the latitude of Havana, Cuba, and has long bay to its east and the Atlantic Ocean to its west. It’s almost always windy here. Winds travelling clockwise across the central Atlantic gets squeezed as they approach the coast of Africa, forcing them to go quickly. While the coastal Sahara was one of rougher physical environments I’ve been to, it’s not totally inhospitable. These intense winds make Dakhla’s bay a great place for kitesurfing, contributing to a modest tourist industry, and the economy also supports fishing and oyster farming.
Day one took us north. We drove along the coast road for an hour or more – passed the occasional security checkpoints, and then headed off road. Even sitting in the back, it was fun off-road driving along bumpy and wild terrain. After another half our or so, we made it to the sebkha, which my colleagues have taken to calling the, “New Sebkha,” not because it’s particularly new, but rather because is has only recently been discovered. A mile or so the west of the New Sebkha was a set of cliffs a few hundred feet tall and to the east was the ocean. The sebkha itself was along the valley floor, just about at sea level, and consisted of one relatively large pool- a few hundred yards wide, and a number of smaller pools that were a few yards wide.
This was some of the weirdest water I’ve ever seen. I brought a hand-held salinity probe with me. It’s a nice little set up, which gives a read out of temperature, salinity, dissolved oxygen and pH. I’ve never seen anything like this salinity, the ponds could be anywhere from two to five times saltier than the ocean. And the water was acidic, nearly a pH of 4, or close to the acidity of tomato juice. Fittingly, it tasted like vinegar and brine.
The landscape was barren, windy, and sun bleaches. In some places the ground was muddy, in other places a quicksand, and by the saltier pools, the ground was caked in large crystals of salt. But, somehow, there was life here. The damp ground just beyond the pools had some scraggly vegetation, and birds passed through here, including some beautiful flamingos. By the saltiest of the ponds- where nothing large lived, we found green algae between the salt and the soil.
As we examined the rest of the system – driving both on the mountain side and the sea side, I tried to think about how this whole system worked. I’m guessing that groundwater drains out of the hills, and through the sandy soils that are near the ocean. The water sits in the hot sun and parched air and evaporates, leaving behind concentrated salt. And the balance of elements in there- must swing this system to the more acidic side- it’s probably more enriched in metals and sulfate- which tend to lead to acidic conditions, rather than sea shells which make waters more basic. We don’t know all that for sure yet, but it might make an interesting research project down the road….
Later that day, Abdeljabbar, an ecologist at the Institute Scientifique, showed us a clam shell that grows in brackish waters. It was probably thousands of years old. These creatures live in Senegal, but not here anymore, a sign of a wetter past when the Sahara was more verdant and lush. What caused the deminse of the wet, green Sahara? Likely changes in earth’s orbit, perhaps accelerated by the influx of people and their livestock. We might not fully know, but it is a reminder of how transitory our earth is, and how our species can alter these natural cycles.
The next day’s sebkha was deeper inland- far removed from the coast and not quite as salty. The water’s salt content was about that of the ocean at its highest, and half as much as the sea in other places. I could see the lower salinity in the abundance of plants- the sebkha was lined with a ring of vegetation. Some of these plants were new to me, but others I recognized from my work in American wetlands. My colleagues were excited to find more fish here, and spent a good deal of time collecting samples- to be analyzed for parasites and DNA.
As remote as the sebkha seemed, it was a small tourist attraction. There was a small sign marking the place, and when we arrived there were about a dozen or so people visiting. Some dangled their feet in the water, and I wondered if people were somehow responsible for the algae bloom taking place in the pools closest to where people parked. But when we sampled at the pool about a half mile south, there were no people- just vast opened cracked drying mudlands. About a mile or so south of this pool. was a long fence- I presumed to keep out cattle, or more likely, camels, that are kept somewhat wildly.
We left the sebkha and headed back to the road. After traversing the desert roads for a half hour, and turned south to a small road sign marker the edge of the tropic of cancer. We took pictures, crossed into the tropics and then turned and headed home. Later that evening, when discussing lines and borders in the desert, I learned I was wrong about that fence- It’s part of a border dispute, both sides have land mines- a reminder that Morocco is a peaceful place in a sometimes rough neighborhood.
The final day we got a closer look at the area around Dakhla Bay. There are oyster farms, some that appear to be growing the oysters off of floating docks- an, “off bottom,” technology that Louisiana is just beginning to experiment with. The team stopped for lunch at a restaurant that serves fresh fish and vegetables. (My guess is that the fish was highly local, and the vegetables were not). And we closed the trip with a busman’s holiday to an enormous sand dune. I could go on about this dune, the wild ripples on by the shore, and the intense vistas from its top- several hundred feet about the sea. I’ll stop describing it, and just leave you with a few pictures.
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