Man made habitat

November 29th, 2019

Few habitats are quite as spectacular for the diver as that of an old mooring line. The line provides prime real-estate for a range of filter feeders, which are suspended in the water column, catching the best possible food carrying currents.

Tunicates and worms by Barry Kaye
View of the lines at Camas Torsa, showing the range of filter feeders taking advantage of the suspended habitat. Photo by Barry Kaye 2018.

Over time the line can become so encrusted with marine life that the weight of it drags the buoy underwater, leaving no trace on the surface, so the appearance of the life encrusted lines on a dive is quite magical! Evantually, however, the submerged buoy collapses, leaving a tangle of line on the seabed. Sadly the habitat degrades from a good place to ‘hang out’, to that of discarded plastic rubbish…

A couple of years ago, on a dive in Loch Sunart, we found quite an extensive network of lines, layed from 16m to the 3m depth, and making for a very interesting dive. Lewis has written up the dives, with a description of some of the organisms found:

The rope site at Camas Torsa, Loch Sunart

Posted in dive trips, Science

Roa dive July 2019

July 29th, 2019
Scorpion fish hiding on the bottom at Roa, 26 July 2019, by Lewis Bambury.
The scorpion fish Taurulus bubais (photo by Lewis) waiting for something tasty to swim by (thankfully we are a little too big for it).

After a string of possible dates this year that we were unable to get in at Roa Island we finally managed a dive on Friday (we had to bring it forward a day to miss the worst of the weather). It was well worth the effort. Visibility was only 2 to 3 metres at best but that is plenty to search the reef for interesting macro life. Our species list – which for invertebrate species goes back to 1968 – grew by at least 2 new species. First to be found were several Goldsinny (Ctenolabrus rupestris), unusual not just as a first for that species, but the first species of wrasse to appear on the list.

Goldsinny, photo at Roa by Barry Kaye, July 2019
Goldsinny, photo at Roa by Barry, July 2019

The next was a nudibranch (that’s a fancy name for a sea slug) called Jorunna tomentosa (pictured below) – it doesn’t have an English name. Both are common species around the coasts of the UK, so of course may have been here all the time, but this is the first time we have them on record here.

The nudibranch 'Jorunna tomentosa' photod by Lewis Bambury at Roa, July 2019
Jorunna tomentosa feeding on one of the sponges (possibly Haliclona sp.) common at Roa. Photo by Lewis Bambury, July 2019

There are many predators in the marine ecosystem and animals have a variety of strategies to help them find food, and avoid being eaten. The Long-spined Scorpionfish is a master of disguise – hiding in plain site by blending its skin colour in with its background; if a crab or small fish comes too close they will be grabbed at lightening speed, predators large enough to tackle it will need sharp eyes to see it, and if they do this fish has a back-up plan – the eponymous long spine on its gill cover, just visible in this picture.

Perhaps the most suprising thing about the dive was the water temperature – depending in depth it ranged from 18ºC to 20ºC. I don’t think that I’ve dived in water that warm either at Roa Island or anywhere else around the Irish Sea. Unfortunately I can’t check my dive logs after a computer glitch trashed them a couple of years ago.

Thanks to Philip and Rebecca for providing shore cover!

Lewis Bambury, July 2019.

Posted in dive trips, Shore walks

Roa Island Beach Walk and Dive

August 10th, 2015

The evening of Saturday 1st August was overcast, with a cold wind, but dry. A small band of us worked down the beach by the new ferry jetty at Roa, following the tide out. The access way used in the construction of the new pier is still comparatively free of marine life, as are the scour pits around the jetty supports, it will be interesting to see how quickly this area gets re-colonised!

Male edible crab (Cancer pagarus) with parasitic barnacle.
Above: One of the interesting finds form the shore walk was this edible crab (Cancer pagurus) carrying a parasitic barnacle.

Peering in rock-pools and under stones we found a range of plants and animals, including the small male edible crab shown above. Despite being male (indicated by the narrow abdomen tucked up under the carapace) he appears to bearing eggs, but the abdomen is actually tucked around the reproductive organs of a parasitic barnacle (Sacculina triangularis). She will have infected the crab by burrowing into his shell shortly after he moulted. Over a period of time she invades the host’s tissues, and re-programs him, castrating him, dictating future moults (despite his small size, this crab may be quite old!) and re-directing much of his energy to the developing barnacle young.

The young barnacles will be released in the nauplius stage of development, when the females will go on to infect future generations of crabs, whilst the males will develop only as far as cyprids, in which stage they will impregnate established females. Parasitic barnacles are common on crabs, and some crab species have infection rates of up to 50% of the adult population. As a consequence parasites are an important factor in limiting crab populations.

Spider crab camoflaged in sponges.
Above: Spider crab (Macropodia sp.) wearing sponge camouflage.

On Saturday 8th August we made the most of a narrow weather window to get a dive at Roa, effectively taking the shore walk out into the permanently submerged part of the channel. Diving conditions were very good for the area, with underwater visibility between 0.5 and 1m. I was paying a bit more attention to seaweeds on this occasion, to try and make up for years of neglect in our usual species hunt, and they were a good range of species between sea level (ca. 2m tide) and about 5m depth. The water in the Bay is generally quite murky, largely as a consequence of the amounts of phytoplankton in the water. These phytoplankton blooms make the Bay one of the most productive ecosystems on the planet, but paradoxically they make life difficult for permanently attached seaweeds, which tend to be stunted, and restricted to comparatively shallow water. Otherwise we saw lots of anemones, crabs, sponges and butterfish. The numbers of peacock worms may be down on previous years, but the general impression is one of a thriving ecosystem.

The butterfish, Pholis gunnellus, a common sighting at Roa.
Above: The butterfish Pholis gunnellus is a common sight at Roa. It gets its name from its slippery, slime-covered body. In previous years we have seen young butterfish taking refuge within the tentacles of the larger anemones (Urticina spp.), where their slime may protect them from being stung and eaten by the anemone, whilst the anemone protects them from other predators.

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Posted in dive trips, Science, Shore walks

Oban in Autumn

October 6th, 2014

The group had another visit to the Oban area in September, the weather was overcast, but mostly dry. The underwater visibility was poor for the West Coast of Scotland, but the diving otherwise good, with a couple of interesting drift dives through the Creran Narrows, and other dives in the surrounding area.
Dramatically lit tunicate
Above: Using dramatic lighting to overcome some of the problems with poor visibility (Photo by Barry – thanks to Lewis for the lighting!)

Many thanks to Gordon for organising this visit. Note: There are still places free on our return visit to Oban on the 10th October (see our diary for more information)

Posted in dive trips

Possible Roa Island dive dates 2013-14

October 23rd, 2013

Following on from the talk on diving conditions at Roa Island, here is a provisional list of dive dates and times over Winter 2013 – Spring 2014, based on tidal information. These have not been checked yet, and are not in our calendar – so use them at your own risk.

2013

Sun Nov. 11 LT 10:40 (meet @ 9:00)

Sat Dec. 12 LT 15:40 (meet @ 14:00) NOTE diving close to dusk
Sat Dec. 28 LT 13:43
Sun Dec. 29 LT 14:50

2014

Sat Jan. 11th LT 14:12
Sat Jan. 25th LT 11:46
Sun Jan. 26th LT 13:04

Sat Feb. 8th LT 12:13
Sun Feb. 9th LT 13:30
Sun Feb. 23rd LT 11:17

Sun Mar. 9th LT 11:25
Sat Mar. 22nd HT 14:59

Sun Apr. 6th LT 10:52
Sat Apr. 19th HT 14:59

Sat May 3rd HT 14:54 Bank Holiday weekend
Sun May 5th HT 15:36
Sat May 10th LT 15:27
Sun May 11th LT 16:18
Sat May 24th LT 15:14 Bank holiday weekend
Sun May 25th LT 16:12
Sat May 31st HT 13:54

You can track diving conditions in Morecambe Bay here.

Thanks to Lewis for compiling these dates.

Posted in dive trips

Estimating diving conditions in Morecambe Bay

October 14th, 2013

By Barry Kaye, Local MCS, 9th October 2013

The talk reviewed a web project that brings together physical information about the Bay from a range of sources, including weather, sea state and river inputs. This data informs our current understanding of physical processes in the Bay. Data are interpreted in a map that shows sea states, wind directions and the levels of principle rivers over the last five days. In addition, graphical displays review sea-sate (wave height and period) and river levels over the last fifteen days.

Graph showing river levels into Morecambe Bay
Graph showing river levels into Morecambe Bay over the last fifteen days (archival data)

The talk went on to look at how physical conditions might interact with the geography of the Bay to influence diving conditions. There is no formal model of the Bay’s ‘underwater weather’, but a number of approaches to developing such a model were proposed.

A link to the observatory is given below, users are advised, however, that this is a ‘work in progress’, there are a few rough edges, and information is provided without warranty of any kind:

[Editor’s note: Sorry, this resource has been removed.]

Posted in dive trips, Marine science update, MCS talks

Roa Island dive 19th June 2013

June 20th, 2013

Roa lifeboat station and Piel Island at sunset just after HW

Above: Photograph of the Roa Island lifeboat station at sunset, with Piel Castle in the background, taken Wednesday 19 June 2013

Our next monthly meeting will take place at Roa Island, a site which has been visited and surveyed by our group for at least twenty years! The meeting, from 18:30 on Wednesday 24 July, is an informal shore walk to coincide with an exceptionally low tide, so we hope to see a lot of sea life exposed on the beach and in small pools that we would normally have to dive so see.

Just so the divers aren’t left out, we have a small number of high water dives planned in the run up to the shore walk*. The first of these was on the 19th June in near perfect conditions. Diving close by the pier and lifeboat station we saw a number of the same creatures underwater, that we will get to see exposed in a few weeks time.

At our August meeting (back at Capernwray Dive Centre) we hope to bring together the shore walk and dives (and maybe earlier survey work) to get a ‘hands on’ picture of life above and below the tide at this very interesting local site.

Please note: The walk in July is suitable for (accompanied) children, but be aware that the beach is very muddy, and you should wear shoes or boots that you are happy to get wet and dirty. If you bring a camera – best to have an underwater housing for it in case… You are free to explore, but most people stay within site of the pier, so it is not important if you arrive late.

Journey time from Lancaster – about one and a half hours, all welcome!

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* Please note that dives at Roa Island are very dependent upon the weather, so there are a number of possible dates in the diary that we shall ‘cherry pick’ from…

Posted in dive trips, MCS talks, Shore walks

Oban dive trip May 2013

May 22nd, 2013

Our latest visit to Oban on the 10th May was wet in every sense of the word – with almost continuous rain, but also some exceptionally good diving. Dives centred on Loch Creran, with the wormery and the inner basin being popular with all of the group.

Following from the talk about surveys in the area on the 8th, we can confirm that there are quite a lot of orange coloured worms (Serpula vermicularis) – these being seen by several divers, and possibly accounting for several percent of the individuals seen. While none were as clearly yellow as the single specimen photo’d back in 2007, this is a pretty strong indication that yellow is at least possible for this species (see gallery).

Less good news on the sea-pen front, however. A dive at Loch Feochan turned out a large number of common sea-pens (Virgularia mirabilis) in very shallow water (3-5m). Amongst these were a large number of juveniles that looked a lot like the specimen photographed at Gallanach over Easter (see gallery). After a discussion with Ron I am forced to concede that there is no current evidence for Funiculina quadrangularis at Gallanach, though Ron has seen this species there on previous occasions… (We’ll have to look again!).

Otherwise a great spectacle was put on by sea-cucumbers, with very large numbers of Psolus to be seen below about 10m in the inner basin of Loch Creran – densities reaching several individuals per square metre. There were some sea cucumbers in the outer basin as well, but in slightly deeper water (ca 18m+). There appears to be at least one other species present – but I’m not sure of its identity (photo in the gallery). Other high spots of the weekend included a thornbacked ray and a couple of dogfish.

Non divers enjoyed the Falls of Lora, and an excellent trip to the Oban Sea Life Centre (where thornbacked rays and dogfish were demanding petting!), but it was a bit damp for cycling or kayaking…

Thanks to Tralee Bay for accommodation and Gordon for organising the trip.

(by Barry 22nd May 2013)

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Posted in dive trips, MCS talks

Oban trip Easter 2013

April 6th, 2013

Sperm whale in Oban Bay, Easter 2013. Photo Chrissy Fletcher

This Easter was one of the coldest we’ve had in several decades, but the weather was clear and sunny on the West Coast of Scotland, indeed, it was the driest I’ve ever seen it there! The cold snap made for very cold diving conditions – coldest at 5°C in the Inner Basin of Loch Creran, with most dives being 6°C and only a couple of degrees warmer on the surface. This kept even the keenest of us down to one dive a day – the rest of the day being spent warming up again! The planned diving surveys were at least in part successful despite being frozen out, and I hope to talk about those at our meeting in May.

In addition to the diving there were kayak trips around the coast, and cycling and walking explorations of Kerrera and diverse places around Oban. Without doubt the best wildlife was to be seen from a hotel on the Oban water-front, however, as Chrissy’s photo above attests – a sperm whale… That was rather unexpected!

More information about the sperm whale sighting linked below:

BBC Scotland – sperm whale sighting in Oban Bay

Hebridean Whale and Dolphin Trust – Whale and dolphin sightings

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Barry

Posted in dive trips

Oban survey planning for 2013

February 24th, 2013

We have two planned trips to the Oban area later in 2013; on the 28th March and 10th May. At our meeting on Wednesday 13th February the trip organisers (Barry and Gordon) spoke about some possible survey activities that could be undertaken on these visits.

Barry focused on Gallanach, to confirm the presence of Funiculina quadrangularis, and the Wormery in Loch Creran, to confirm the identity of the blue worms photo’d in 2012 (MCS dive trip to Oban (Sept 2012))

Gordon looked to explore new areas around Loch Creran. He also noted that the tides during our trip in March might give us some very good drifts through the Creran Narrows.

Thanks to everyone to turned out for this meeting – in pretty horrid weather!

Posted in dive trips, MCS talks