Images or video of Sargassum filicinum in Asia?

[drbill]

As divers in SoCal may be aware, the Asian kelp Sargassum filicinum (native to Japan and Korea) invaded our region several years ago (see column link below). It has spread like wildfire and now chokes out native vegetation and invertebrates in several areas including the leeward coast of Santa Catalina Island.

Star Thrower Educational Multimedia (S.T.E.M.) Dive Dry Column

I am looking for stills or video of this species in its native habitat to get an idea of the density it achieved where it is a natural component. I would greatly appreciate anything divers from Japan or Korea could provide.

I would also be interested in stills or video of any SoCal species (such as Macrocystis pyrifera or Pelagophycus porra) that may have been introduced to Asian waters by trans-Pacific shipping.

TIA

 

[The Mushroom King]

Hi Dr Bill,

At least at first glance I can't think of seeing that kelp in any particular density near tokyo. But a quick search reveals that the Japanese common name is (シダモ&#12463 Shidamoku, and it can be found in the south parts of Japan (found references from Kobe and Kyushu Universities.)

Maybe others around can add some info. (and I'll keep my eye out for it next time I'm in the water.)

 

[drbill]

Thanks for the new information. I have seen one picture from a friend in Japan which appears to depict this species at pretty low density. It is amazing to see how completely it chokes out other marine life here in our waters.

 

[TJO]

There is a lot of that kind (I think it is the same) in the Japanese sea side. I mean *a lot*. I will take a video next time I am over there, which may be some months though. I will also see if I can find any at Shikoku (Pacific) next weekend.

 

[drbill]

That would be much appreciated TJO. The speed with which this species has spread is amazing, as is the density it achieves here in our waters.

 

[bill22]

Hi Bill,
Just happened to notice your post. I'll include the photo here.

As I recall it got much thicker, but then started to die off in late spring. None to be seen right now. I remember that we had a few dives when it got so thick that we gave up trying to swim over the top and dropped underneath. My buddy lost his knife swimming through it. It was just another one of those little inconviences we put up with. Hayama is never really an easy dive anyway )

I was told by one of my friends that a new area I explored on my last dive at Hayama is so thick in the spring that its not diveable. I'll get some more photos for you this spring when it comes back.

 

[drbill]

I don't think I have ever seen a kelp of this nature (basically an understory species here below our giant kelp) so completely dominate the bottom from about 10-15 ft to depths of 70 ft. Of course I remember your picture, Bill. Your added information in your post is interesting as well. We find it dies off in late spring, then new plants emerge in fall as the water cools and completely dominate many sites here throughout the winter and early spring.

 

[bill22]

I don't think I have ever seen a kelp of this nature (basically an understory species here below our giant kelp) so completely dominate the bottom from about 10-15 ft to depths of 70 ft. Of course I remember your picture, Bill. Your added information in your post is interesting as well. We find it dies off in late spring, then new plants emerge in fall as the water cools and completely dominate many sites here throughout the winter and early spring.

Possibly I just didn't notice it until it started getting really thick in the spring. Water temp is dropping now. November 2nd was 21.6C (about 71F). November 22nd was 17.9C (just over 64F).

On January 6th, earlier this year water temp was 14.4C (58F). I didn't dive Hayama in February. We made a trip to Izu that month and we were diving in Tokyo Bay. (Hayama is Sagami Bay on the opposite side of the Miura Pennisula) My Japanese friends were harvesting kelp for miso soup I'll include a photo.

Water temp in Tokyo Bay in February was running around 8.3C (47F). On March 8th when I made my first dive at Hayama in 2 months, the seaweed was thick enough that I mention it in my dive log. I didn't log it, but I remember by May when water temp was back up around what it is now that it had thinned out. Didn't see it all in the summer.

Hope this helps. Now that I know what it is I'm looking for, I'll monitor it for you this winter and I'll try to make it a point to make it over to Hayama more often. I'll look for it in Tokyo Bay also. I'll keep you posted.

 

[drbill]

Thanks, Bill. Our temperature fluctuations here are not as wide. During the "warm" period (surface > 65 F) the Sargassum is almost non-existent. I start seeing small plants about 6-10" across in early fall. Once the temps at depth start dropping into the lower 60's, it takes off. This year the temps stayed unseasonably warm until last weekend, and the Sargassum had a slow start but is starting to take off now.

Evie Go said you will be in the Philippines in March. You may have mentioned that to me earlier. If all goes well, I hope to be filming for the resort on Palawan in late March. Will extend my stay to about a month with the intent of diving other areas like Anilao, PG, Tub, etc.

 

[The Mushroom King]

Water temp in Tokyo Bay in February was running around 8.3C (47F).

8.3 !!!???

I've never seen it drop below 14 around izu, which is within a short drive south of Tokyo....and the quick search I did for hayama in feb last year said about 12...
you sure?