Rockpooling in Flushing

The wind has picked up and will ruin any chances of getting good seaweed shots this week. Too bad, but what can you do? A bit of rockpooling I guess. I took my son out to our local beach in Flushing where the rocks gently slope into Penryn River. Although there are no ‘proper’ rockpools, low tide gives access to a mixture of maerl sand and rocks that can be turned over. It is silty and definitely not very pretty, but there is always something to find. It was an especially good weekend for finding fish, seeing Shannies, Tompot blennies, Rock gobies, Gunnels, Worm Pipefish, Shore Rocklings and a tiny Eel, as well as Sea Scorpion eggs. (One Shanny was quite big and proceeded to bite my son’s hand; he was very brave and we slowly put it back.)

Invertebrates were plentiful too. The main mollusc here is the Variegated Scallop Chlamys varia, which is attached underneath every single rock. We found our smallest Great Scallop Pecten maximus as well. We found some Sea lemons Archidoris pseudoargus and lots of Yellow-plumed Sea slugs Berthella plumula (which apparently can secrete sulphuric acid when disturbed…). A small selection of what we found below, all pics taken with an Iphone.

Two November Boat Dives

I had the pleasure to go on two dives with Mark Milburn of Atlantic Scuba on the ‘Stingray’ RHIB this weekend and last, leaving from Mylor Harbour (see photo above). The first dive was in the Helford Pool, a deep area in the otherwise shallow Helford river. Buddied up with Sue and Al, we descended to 18 meters to swim over a gravelly area covered with tunicates and sponges. This was a drift dive but we did not get all the way to the eastern end of the pool where some small maerl beds are located. Swimming crabs and Leach’s spider crabs were very common; there were not many fish though. One exception was a cute little John Dory Zeus faber. I was struggling to take any decent photographs, in part because I have not used my strobe much yet and because I should have two, not just one! Sue Barnes kindly let me use a photo she took of the John Dory for the blog; also added is a photo of a sponge, one of the few half-decent ones I managed to take: The dive today took us to the cannon ball site, roughly a mile from Pendennis Castle, and an area where many of the cannon balls fired for practice ended up. With buddy Alex we descended to around 16 m using a shot line. Again a flat ‘rubbly’ area with few fish. The seafloor was covered with Common brittlestars Ophiotrix fragilis. The viz was quite good, and it was much lighter than the previous dive. I also had *a bit* more luck with the strobe. Leach’s spider crabs were common, and we also saw some Sea lemons, Doris pseudoargus, a large seaslug. Up next three common species: a little Rock goby Gobius paganellus, the colonial Antenna hydroid Nemertesia antennina and the colonial sea squirt Aplidium elegans (thanks David Fenwick). I keep my eyes open for seaweeds too of course, there were some small red species and what I suspect is Desmarest’s prickly weed Desmarestia aculeata. I found out back on the boat that I completely missed a small octopus that Alex pointed out, argh! I was very happy though that I managed to spot an Imperial anemone Capnea sanguinea, which is an uncommon species. The photo of this all-white individual was taken without a strobe; I really should have taken more time to get a decent shot. A good reason to go back though, and maybe we can spot some cannon balls then too. The water is 13-14 degrees and so it is still doable to dive with a wetsuit.

a very low tide at Flushing

I made some pics last weekend when low tide wasn’t very low, but since this weekend the tides hit record lows I will first post about these finds. First up, the sheltered estuarine conditions in Penryn river in Flushing, opposite Falmouth’s port. The conditions are silty, with lots of sponges, tunicates, variegated scallops, sea lemons, European cowries and enormous amounts of Squat lobsters (see also this old post). With the tide this low, we were able to see some other stuff as well. The water went as low as the Eelgrass:IMG_6170Shannys, Rock gobies, Rockling, Worm pipefish and (to a lesser extent) Butterfish are easy to find in Flushing. Today we saw for the first time two Connemara clingfish Lepadogaster candollei (first pic). Next a Rock goby Gobius paganellus. We also saw many large Tompot blennies Parablennius gattorugine which live subtidally and only now could be seen:

IMG_6172

IMG_6105

IMG_6186The real surprise of the afternoon was a juvenile Common lobster Homarus vulgaris. All in all a very succesful trip!IMG_6138

IMG_6141

Netting

With the aquarium ready and a neap tide, I resorted to some fishing from the quay with my humongous (>2.5 meter) net. This thing is a pain when moving/emigrating but I’m glad I’ve kept it. It is custom-made for RAVON: Reptielen Amfibien en Vissen Onderzoek Nederland (Reptiles Amphibians and Fish Research The Netherlands), a great club that I joined for a while when living in Holland. (The ‘fish’ in the acronym covers only the species living or migrating in fresh water). The net can be bought via the RAVON web shop; at the time they also sold a handy cuvet:

IMG_0483I have scraped along the sides of the main quay in Flushing a number of times now (btw, the quay was built by the Dutch; Flushing is named after Vlissingen in Zeeland, the old Cornish name of the village is Nankersey). Two-spot gobies (the most common semi-benthic species), a rock goby and even a Fifteen-spined stickleback Spinachia spinachia have ended up in the net. The last species I did not keep, as they prefer live food that I cannot offer them, but I took it home for a quick pic:

IMG_8687I never caught young mullet, a species that is great for the aquarium, which is strange as they are common around water fronts. This weekend to my surprise I caught two wrasse for the aquarium: a Rock cook Centrolabus exoletus and a Corkwing wrasse Symphodus melops. Two very beautiful little fish (both species grow up to 15 cm, these were around 5 cm). Here the Rock cook Corkwing wrasse that looked superficially like a Rock cook but back home in the aquarium showed its distinctive spot on the base of the tailfin (best way to identify is counting scales and rays but that is almost impossible now; useful info on wrasse determination on this angling site):

IMG_0476

IMG_0473

top ten animals for the unchilled aquarium: 10 – 6

As the aquarium is currently in a state of limbo, I thought it would be fun to take a look at the critters that have been most rewarding to keep in the year or so I’ve had my aquarium. Based on my personal experience, I have made an, admittedly completely arbitrary, top 10 of animals for a Cornish (or North-Western European) marine aquarium. I picked animals that were both easy to collect (i.e. common), easy to keep (not requiring live food and resistant to water temperatures up to 25C) and fun to watch. Here goes with the first part of the list!

10: Netted dogwhelk Hinia reticulata

IMG_0748

Not the prettiest of molluscs maybe, but very easy to find and very easy to keep. Burrowing in sand, and moving surprisingly fast over the bottom when smelling food. Their smaller (and prettier) cousins the Thicklipped dogwhelk Hinia incrassata never survived for long in my unchilled tank.

9: Common hermit crab Pagurus bernhardus

IMG_1020Hermit crabs are especially fun to watch scurrying about. Mine never really lasted very long but that is probably because of predation by blennies and gobies (see below)….

8: Shanny Lipophrys pholis (or Rock goby Gobius paganellus)

IMG_0203Shannies are probably the most common fish to find in rock pools. They are very easy to keep, their coloration is not particularly vivid but not dull either and they are quite active. The only downside is that they prey on molluscs and other small critters. Feeding them a bit more might prevent this, but especially the rock gobies are so voracious that I doubt that (one was so swollen I thought it was dying, until I realized that it had gorged itself on defrosted artemia…). Montagu’s blenny Coryphoblennius galerita is prettier and smaller than the shanny but much harder to find (see this post for experiences with other fish species).

7. Thicklip grey mullet Chelon labrosus

IMG_0675

Most rock pool inhabitants live on or near the rocks, but it looks nice if the aquarium also have some fish swimming in the water column. Mullet are very common, and small individuals form nice silvery schools (which are almost impossible to photograph as you can see). They don’t really interact with the other tank inhabitants.

6: Painted top shell Calliostoma zizyphinum

IMG_1949

One of my favorite local molluscs: a bright purple shell with an orange colored snail inside. Shells are never covered with algae as the snail wipes it clean with its foot (the shell can still be damaged of course as seen in this individual).

The next post will feature the top 5 of animals for the unchilled aquarium.

new sand

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:

IMG_2996

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:

IMG_3128

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:

IMG_3133

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:

IMG_3147

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:

 IMG_2167

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):

IMG_3139

 

Mud pooling

When it was very low tide last week, I decided to skip the ‘rock pools proper’ on my local beach in Flushing and to check out the zone just below where the rocks and the sandy bottom of Penryn River (an arm of the Fall Estuary) meet. All common rock pool inhabitants – winkles, top shells, edible crabs, worm pipefish and shannies – still live here, but some other organisms are more abundant here than in the rock pools.IMG_2881

Sponges are very common in this silty environment, especially the Estuary sponge Hymeniacidon perleve:IMG_2877

The Breadcrumb sponge Halichondria panicea:IMG_2882

In addition to sponges, I noticed quite a lot of the colony-forming ascidian Botrylloides leachi (see previous post). That explains why I could also find a couple of European cowries Trivia monacha, their predator. Also very common here are the Variegated scallop Chlamys varia and the Thicklipped dog whelk Hinia incrassata (top right picture). I am not sure what the slimy beige stuff is!IMG_2920

I spotted a couple of new things as well, the Red speckled anemone Anthopleura ballii:IMG_2901

IMG_2905

Also a first, a Sea spider Nymphon (gracile?):IMG_2886

IMG_2892

I found a large patch of these beautiful eggs:IMG_2931

and someone guarding them, a rock goby Gobius paganellus:IMG_2935

A Butterfish Pholis gunnellus:IMG_2947

Very common were little Squat lobsters Galathea squamifera (no picture), rapidly swimming backwards to escape. Even more abundant were these little Hooded prawns Athanas nitescens:IMG_2924

tank update

Time for an update on the tank. Switching to two lamps instead of one looks good but has not brought the iridescence of the Bushy rainbow wrack back. I could not resist putting a new specimen in. Iridescence is defined as the property of certain surfaces to appear to change color as the angle of view or the angle of illumination changes. Left: viewed from below, right: viewed from above.

IMG_2407IMG_2409

I noticed that the underside of the rock the weed was attached to harbored a nice little strawberry worm, but before I could photograph it, the large rock goby gulped it down. It is noticeable that the fish have full bellies after putting in a new piece of seaweed, which is no surprise as there is so much growing on and in it.I have seen the very cute amphipod Caprella acanthifera which looks like a tiny, marine cross between a praying mantis and a caterpillar, but since they did not come not near the glass I could not get a good shot. I have seen one Cushion star Asterina Phylactica as well, which looks nicer than the light grey Asterina gibbosa I have. I also noticed a couple of Cerithiopsis tubercularis (3-4 mm):

IMG_2102

The tank is completely full of snakelocks anemones, hundreds maybe:

IMG_2410

IMG_2107

In the foreground an Idiotea isopod; there are many of these sitting on seaweed branches and occasionally swimming around, although most of them will probably be eaten by now. Finally, three seaweeds have started to grow from the pump outlets. Dudresnay’s whorled weed, a fine purple weed and a broadleaved red seaweed. I have placed adult plants of the latter species (30 cm or so)  in my aquarium before, but these were quickly eaten. It is either a type of laver or dulse, but I am not sure. It has also settled on the glass, but seldomly grows ‘leaves’ on there. Growing in the water current protects the weeds from predation from shrimps, let’s see how big they can grow!

IMG_2354

Fish

When looking for pictures of the squat lobster, I realized I have quite some neat old pictures to post. I should have started the blog when starting up the aquarium to keep things chronological, I will use the next couple of posts to get rid of this back log. First the fish. I have two Rock gobies Gobius paganellus in my tank. The big one is voracious and after a feeding session has a visibly distended belly. It is a curious fish that often comes to check me out when I am taking a picture. It is beautiful too:

IMG_0085

IMG_0229

IMG_0225

However, I will attempt to catch it and release it, as I suspect it to be a bit too large (three inches) and rash. My worm pipefish Nerophis lumbriciformis are very shy and they might be bullied by large gobies and blennies. I actually suspect the big rock goby to have eaten my recently disappeared beautiful little Montagu’s blenny Coryphoblennius galerita, a species I have only found one time:

IMG_0631

IMG_0685

A worm pipefish Nerophis lumbriciformis. To replace the rock goby, I will try to catch some Two-spotted gobies Gobiusculus flavescens later. This species is also beautiful, but smaller and it spends more time in the water column which is nice. It is not a rock pool inhabitant though; it lives among seagrass. I have seen many last year when snorkelling. I need to look into a good net to catch them! I had two  large Shannies Lipophrys pholis as well that I released again, I still have a small one left:

IMG_0764

I also had three thick-lipped mullet Chelon labrosus in the tank. These fish are quite ugly as adults, but juveniles are nice, restless silver fish. All  fish mentioned above are benthic (hang around the rocks rather than in the water column), whereas this species mostly swims at the surface and so really adds to the aquarium. I released these three when changing up the tank once and I now regret that. They are fast swimmers so quite difficult to catch (at least with the small aquarium net I use). Since they are so restless I did not manage to take a decent photograph. I have also added a Shore rockling Gaidropsarus mediterraneus and the cling fish the Cornish sucker Lepadogaster purpurea at one point. I should have known that these were mistakes as these are fish that mainly hide under rocks and I have not seen them since adding them to the aquarium. I will post some pictures of these fish in their natural habitat later.