Last summer was a pretty cool one here in SoCal. As many divers know, cooler water contains more nutrients, and there is an inflection point at 68 F (20 C) where nutrient levels drop off rapidly. The cool temperatures (usually not exceeding 68-69 F here) during what should have been the warmest period, late summer and early fall, resulted in presence of higher nutrient levels than would normally be available for algae (including giant kelp and phytoplankton).
During August I hypothesized that the cool temperatures and therefore higher nutrients would permit our giant kelp (Macrocystis) forests to remain healthy through the rest of the year. I can't remember seeing the kelp forests as rich and luxuriant as they are this year since the mid 70s (before the warming trend began in the late 1970s). Further, the presence of healthy giant kelp would result in overshading the noxious exotic Asian alga Sargassum horneri [= filicinum] that has come to dominate the waters off Catalina's leeward side the past five years.
I did not dive from late October til December 27th, so I had no direct way of assessing whether I was correct in postulating this. I was hearing from other divers that the Sargassum was rather limited this year. Last year I stopped my night dives in early November because it was very thick by that time.
On the 27th I did two dives in the Casino Point dive park with Rick (riguerin), his son Brandon, Kathy (KathyDee) and Lorri. I was very pleased to see that the Sargassum was largely absent from areas where it formed an almost impenetrable "forest" (more like chaparral since it only gets to about 15' in length). There were 9only a few spots I saw in the park where the Sargassum had formed clusters.
With its presence so restricted, there won't be near as many reproductive components cast off this year. I don't know their viability over time, but assume there are plenty to be activated next fall when their annual growth cycle begins again.
Maybe we can get some control over this nasty stuff, at least in small areas like the dive park (which becomes an official MPA this year!!!). I hope so.
During August I hypothesized that the cool temperatures and therefore higher nutrients would permit our giant kelp (Macrocystis) forests to remain healthy through the rest of the year. I can't remember seeing the kelp forests as rich and luxuriant as they are this year since the mid 70s (before the warming trend began in the late 1970s). Further, the presence of healthy giant kelp would result in overshading the noxious exotic Asian alga Sargassum horneri [= filicinum] that has come to dominate the waters off Catalina's leeward side the past five years.
I did not dive from late October til December 27th, so I had no direct way of assessing whether I was correct in postulating this. I was hearing from other divers that the Sargassum was rather limited this year. Last year I stopped my night dives in early November because it was very thick by that time.
On the 27th I did two dives in the Casino Point dive park with Rick (riguerin), his son Brandon, Kathy (KathyDee) and Lorri. I was very pleased to see that the Sargassum was largely absent from areas where it formed an almost impenetrable "forest" (more like chaparral since it only gets to about 15' in length). There were 9only a few spots I saw in the park where the Sargassum had formed clusters.
With its presence so restricted, there won't be near as many reproductive components cast off this year. I don't know their viability over time, but assume there are plenty to be activated next fall when their annual growth cycle begins again.
Maybe we can get some control over this nasty stuff, at least in small areas like the dive park (which becomes an official MPA this year!!!). I hope so.
