I joined a seaweed identification get-together at the Cornwall Wildlife Trust organised by Matt Slater last week. It was fun to chat with likeminded people and also made me want to stick my head underwater again! The weather has been horrible for over half a year now and I have been in only a few times, with little chance to take decent photos, hence the blog inactivity. This has been especially frustrating as March is the best month for seaweeds (see the 2017 Falmouth Seaweeds tag) and I am missing my window. I therefore jumped in the next day. The tides were at their very lowest, actually too low for most of my usual rockpool spot! The viz was not great due to the 20+ mph winds but just about good enough for the fisheye lens. I really hope for some good weather in the next 2-3 weeks to be able to make the seaweed photos I really have in mind.The very top photo is Berry wart cress Sphaerococcus coronopifolius shot with a very shallow depth of field. The single stone above hosts a whole variety of species. The largest is Slender wart weed Graciliaria gracilis and just as the Berry wart cress it is covered in mucus threads, which must come from the tiny gastropods Rissoa parva that can be seen on it when you zoom in. To the left the wiry Black scour weed Ahnfeltia plicata. To the back the invasive Devils tongue weed Grateloupia turuturu. Green Ulva and young kelp can also be seen. Below some Harpoonweed Asparagopsis armata. The snakelocks anemones Anemonia viridis were also out in force. I hope the weather settles soon!
More seaweed photos, taken a couple of days after the ones in the previous post, when it was overcast and the water was less clear. The photos are not as good, but there are still a lot of interesting species to see. Below some photos showing the diversity of species next and on top of each other. In the last two months, most species have been growing quite a lot. There are quite large patches of Slender-beaded coral weed Jania rubens. Bushy rainbow wrack Cystoseira tamariscifolia plants are completely overgrown with all kinds of epiphytes, seaweeds, sponges and colonial tunicates, and often have a Nursehound egg case attached. Next, photos of individual species. First some flat reds: Leafy rose weed Rhodophyllis divaricata, Beautiful fan weed Callophyllis laciniata, Branched hidden ribs Cryptopleura ramosa (probably), the invasive species Devil’s tongue weed Grateloupia turuturu and Under tongue weed Hypoglossum hypoglossoides. After that, two species that look a bit similar: left the reddish Discoid fork weed Polyides rotundus and right Clawed fork weed Furcellaria lumbricalis. The former is one of the most common species (also on the photo above it) but difficult to photograph as it usually sits on the white sand. After that, Juicy whorl weed Chylocladia verticillata. Last, two quite unassuming species: Black scour weed Ahnfeltia plicata and Sea flax weed Stypocaulon scoparium. Identifications made possible using the must-have Seasearch Guide to Seaweeds of Britain and Ireland, David Fenwick’s excellent aphotomarine website (and personal communication) and the good people of the Seaweeds of the NE Atlantic facebook group (any mistakes are my own).
A final post summarizing my experiences with seaweeds and writing this, I have regained my enthusiasm for trying to grow seaweeds in my aquarium. My New Years Resolution will be to get a proper marine planted tank going again! (The fact that the aquarium, currently devoid of seaweeds, looks less than great at the moment has made the decision to change it around easier as well…)
5. Some seaweeds establish naturally in the aquarium
I mentioned in the first seaweed post that it can be hard to ‘plant’ seaweeds in the aquarium but sometimes they just settle by themselves. One of my favourites, Chrysymenia wrightii (consistently misidentified as Dudresnay’s whorled weed throughout this blog…) started growing spontaneously from a rock:
This is currently happening with bright green Sea lettuce Ulva and what is probably Devil’s tongue weed Grateloupia turuturu. The outlet grid of the Tunze nanostream is a good place for seaweeds to settle it seems; I have currently a little pluck of Flax brick weed Chaetomorpha linum growing and had a couple of other species there in the past too. Spontaneous growth is of course the best way to get a seaweed aquarium going.
6. A list of Seaweed species I had in my aquarium
Perhaps of interest to a handful of people… I have tried to list all seaweeds I managed to identify and remember, and whether they did well (YES) or not (NO) in my unchilled aquarium (lighting spectrum and intensity used varied somewhat over time). Why some species did not do well I have no idea (see previous post); in some cases, seaweeds were eaten. I have not tried larger species such as Kelp as my aquarium is not that big.
Above: Green (Velvet horn), Brown (Wireweed) and Red (Harpoon Weed) seaweeds in the aquarium.
Solier’s red Stringweed Soliera chordalis – YES
Chrysymenia wrightii (no common name) – YES
Dulse Palmaria palmata – NO (eaten)
Harpoon weed Asparagopsis armata – NO
Common coral weed Corallina officinalis – NO
False eyelash weed Calliblepharis jubata – NO
Dumont’s tubular weed Dumontia cortorta – NO
Clawed fork weed Furcellaria lumbricalis– NO
Red grape weed Gastroclonium ovatum – NO
Bunny ears Lomentaria armentata – NO
Devil’s tongue weed Grateloupia turuturu – YES
Iridescent drachiella Drachiella spectabilis – NO
A tangle of different Red Seaweeds:
Estuary wrack Fucus ceranoides – YES
Serrated wrack Fucus serratus – YES
Bushy berry wrack Cystoseira baccata – NO
Bushy rainbow wrack Cystoseira tamariscifolia – NO (still my holy grail)
Wireweed Sargassum muticum – YES (this proved to be the easiest one of all to keep)
Common green branched weed Cladophora rupestris – NO
Flax brick weed Chaetomorpha linum – YES
Sea lettuce Ulva (lactuca) – YES
Velvet horn Codium tomentosum – YES
So 9 out of 21 species did OK in my aquarium which is actually not too bad (although I have forgotten a number of species that did not do well). Unsurprisingly, the invasive species were easiest to keep (5 YES in 16 natives, 4 YES in 5 non-natives; the difference is not statistically significant though).
Finally, I just wanted to mention that I have been updating the ‘links’ page recently. Regular commenter Marius has recently started a great blog about his new native marine aquarium with organisms collected at the west coast of Ireland: Irish Rockpool Aquarium Adventures, go check it out. A very nice rock pooling blog also is The Salty Scavenger which features loads of seaweed pictures. From now on, I will also register my rock pooling finds online here; with lots of volunteers doing that a great resource will be created that can be used for protecting marine habitats which of course is very important! I have also added a bunch of really useful links to facebook pages, for instance the ‘Coldwater Marine Aquarium Owners‘ group page.
These are my local rock pools at the Trefusis headland near Flushing. On the right is Penryn River (which is not a river at all) with Falmouth on the other bank. Further to the right around Falmouth is the open sea. To the left the Fal Estuary (or Carrick Roads) going all the way to Truro, the capital of Cornwall.
The seaweed composition had again changed since I last visited. This time there was one red weed dominating the pools, I believe it is the Pacific invader Devil’s tongue weed Grateloupia turuturu (which appeared in my aquarium at some point as well):
The most common sea slug (nudibranch) here is the Sea lemon Archidorus pseudoargus:
Welcome to this most obscure of blogs, my dear reader. The aquarium is a bit of a mess at the moment for a variety of reasons. First of all there are a lot of algae growing; I have a bag with Rowaphos hanging in the back compartment to remove phosphates but this does not seem to help much (I have had good experiences with before though). Second, one of my pumps broke and so filtration runs at half capacity. Third, the mixed success of planting many different seaweeds has left loads of detritus in the tank. I have made large water changes which helped a bit. An additional tank for experimenting would be nice to have… Fourth, I have been unlucky with some of the seaweeds: the Wireweed grew really well, but the large size meant it caught a lot of the current and was easily dislodged. The Dudresnay’s whorled weed Dudresnaya verticullosa was growing really well (see here) but broke off from the rocks and could not be replanted:
I could not attach the fine red seaweed (see last post) either and did not want to have it floating around so I have removed it. My nice red seaweed streaming from the pump outlet, most probably Devil’s tongue weed Grateloupia turutu (as the name indicates, another invader from the Pacific), broke of. A crap picture of both weeds:
I changed the white gravel with finer, beige Maerl gravel (Cornwall’s equivalent of coral sand, see previous post) here placed in a bowl for contrast:
I released my Shanny as well as the largest of the two Rock gobies. The former attacked to many of the snails (it was getting a bit of a mollusc graveyard) and the latter was just too voracious in general. The final straw was seeing it swimming around with half a Worm pipefish sticking out of its mouth (I still have a bunch of those). The Shore rockling did not survive, but I caught a glimpse of the Shore clingfish when I removed some of the rocks from the aquarium. The juvenile albino Edible crab (if that’s what it is) and the European sting winkle Ocenebra erinaceus I recently caught both still do well, as is a juvenile Shore crab Carcinus maenas:
The Netted dog whelk Hinia reticulata is not one of the most impressive looking snails, but they do very well in the aquarium, burrowing and moving around:
I am not sure whether replacing one of the actinic lamps with the daylight lamp was such a great idea, the tank looks too yellowish now, especially with the Maerl sand…However, I will stick with it and see whether it helps future attempts to successfully keep Bushy rainbow wrack Cystoseira tamariscifolia (i.e. to retain it’s iridescence). If not, I’ll go back to the original lighting. I will not do too much with the aquarium in the near future as I want to get rid of the algae first. There are not many critters in the tank, which should help (I have only introduced a nice big Snakelocks anemone Anemonia viridis recently). I will do some more water changes and order a new pump. Only then will I slowly start experimenting with seaweeds again.
I am still unsure about the chiller, but with the weather getting warmer it might be more than just a luxury to have one. Apart from the price, it standing on the floor next to the aquarium with tubes sticking out is what I don’t like about the idea though. It will also not be silent, but perhaps I could get away with disabling the noisy hood fans, resulting in an overall quieter aquarium. The stripped-down tank (note that the red encrusting algae/seaweeds at the top of the tank have died (turned white) as they were exposed for a couple of hours when changing water):