Last week I went for a little swim at the usual spot at Castle Beach. The viz was nowhere near as good as last month, but still OK. There are schools of sand eels and sand smelt and I even saw an eel. The contrast between growing brown seaweeds and withering red seaweeds has become even greater. Below you see some yellowed Harpoonweed and a ‘forest’ of Thong weed covered in epiphytes. As the light was a bit subdued, I focused on the most shallow area. The bare parts of the rock are covered with barnacles, dog whelks, sting winkles and limpets. The seaweeds are mainly Serrated wrack Fucus serratus, Sea lettuce Ulva, Grape pip weed Mastocarpus stellatus, some Ceramium and Laver Palmaria palmata, as well as Dumont’s tubular weed Dumontia contorta.
I have been a bit busy and so the photos below are some weeks old. The seaweeds are in decline already it seems. Actually, that is not true, there are plenty of seaweeds growing, but some of the prettier ones are dying off and some of the uglier ones are taking over. The window to take the nicest rock pool shots is quite short, pretty much early spring only. The ubiquitous False eyelash weed Calliblepharis jubata is yellowing, the green Sea lettuce Ulva lactuca is starting to cover everything and the Red grape weed is getting ‘fluffy’. Not the best session photo quality-wise and probably the last of the year. The Bushy rainbow wrack Cystoseira tamariscifolia is abundant and looking good (on the photo with Discoid forkweed Polyides rotundus) and I managed I nice shot of young Thong (or Spaghetti) weed Himanthalia elongata. I have done some more research into ‘proper’ underwater cameras and was tipped of about the Canon G16 (thanks Thomas from HydroMotion Media), maybe something for next year….The past couple of times when focusing on the seaweeds I also encountered some animals (it is hard not to). Many Snakelocks anemones Anemonia viridis, with some having very short tentacles. Next, a Decorator crab Macropodia rostrata covered in Banded pincer weed Ceramium. Mermaid’s purses (egg cases) of the Bull huss/Greater-spotted Dogfish/Large-spotted Catshark/Nursehound Scyliorhinus stellaris seem to be exclusively attached to Bushy rainbow wrack. Finally, a Stalked jellyfish Haliclystus octoradiatus on Wireweed Sargassum muticum.
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.
In addition to animals, loads of different seaweed species could be found washed up on the beach in Pleneuf-Val-Andre:
Some of the species would look great in the aquarium I am sure. For instance Fine-veined crinkle weed Cryptopleura ramosa:Pestle weed Gigartina pistillata: (EDIT 2017: does not look like this species at all, be very suspiscious of my seaweed ID skills in older posts please!)Maybe a Plocamium species, I am not sure. I really like my Seasearch Guide to Seaweeds of Britain and Ireland, but it does not contain a key and I find it hard to determine some species based on a photograph.What would be great is to have a seaweed key app. I saw a great one this weekend for trees: leaf snap: take a picture of a leaf with your phone or tablet and it automatically gives you a list of best hits based on the outline (and perhaps colour, I don’t know), it worked really well. Seaweeds (actually pretty much all organisms) are too complex in shape, size and color for this. However, I could see an app working where the first screen would give you a number of pictograms, eg ‘dark encrusting reds’, ‘chalky reds’, ‘feathery reds’, ‘fan-shaped reds’ etc. After touching a first pictogram, new ones would appear, for instance to select the branching pattern, ‘irregular’, ‘whorled’, ‘opposite’ or ‘alternate’ and so on. Instead of such a purely dichotomous approach, it could also be possible to be presented with a wide variety of pictograms describing different properties (eg, colour, overall shape, texture, location on the shore), where it is possible to skip properties you are unsure about and still go ahead with the next steps. This would be a brilliant resource and help me identifying weeds such as this one:Anyway, a final seaweed (there were many, many more but this one I immediately recognized): Sugar Kelp Saccharina latissima. It is surrounded by various species of flat and tubular Sea Lettuce Ulva:
It was too cold and windy to spend a lot of time on the beach, so I took a closer look at my seaweed catch back home. I was amazed at the diversity of organisms growing amidst the weeds. A lot of them are easily overlooked when rock pooling as you need some time (and preferably a comfortable seat) to find them. Below Bushy rainbow wrack with epiphytic False eyelash weed and Pink plates Mesophyllum lichenoides (I will not give the Latin names of species described in preceding posts for brevity). Some bright green sea lettuce Ulva, a grey topshell Gibbula cineraria, a snakelocks anemone Anemonia viridis and in the middle a bright orange colony of the tunicate Botrylloides leachi: I found many large Breadcrumb sponges Halichondria panicea but the picture I took did not turn out to be in focus. I do not know what the organism below is, perhaps a bryozoan (please feel free to comment!). I am not sure what this is either! Dog whelk Nucella lapillus eggs (I now also notice a tiny brittle star in the middle): Egg cases of the thick-lipped dog whelk Hinia incrassata: A small snakelocks anemone; interestingly enough all of these were the green variant (with purple tips) and there were none of the pinkish ones. I have read some interesting notes about aggressive behaviors between the two types, something to look into for a future post. A Marbled Crenella Modiolarca tumida, a tiny bivalve typical of seaweed holdfasts: A tiny White tortoiseshell limpet Tectura virginea: I saw something creeping out of the seaweeds on the floor out of the corner of my eye: a small Long-legged spider crab Macropodia rostrata. This species adorns itself with seaweeds for camouflage: