Dorset Seasearch 2005

2005 was the tenth year of Poole Harbour Deepening Seasearch diving in . The winter of 2005 saw the start During these ten years over 200 of a massive project to deepen www.seasearch.org.uk divers have contributed more than the main shipping channel into 500 Seasearch forms, making Poole Harbour. Up to half of the Using remote-sensing data to a substantial contribution to the material dredged is being used for target Seasearch diving understanding of Dorset’s marine beach recharge on local beaches Choosing where to Seasearch can environment. - the rest (the siltier sediment) is be a daunting task. Though we do The map below shows all 2005 disposed of at a licensed disposal need information from all parts of Seasearch dives. ground in Bay. This the seabed, it would be a waste is a significant increase in the of time, and of the enthusiasm of scale of dredge spoil disposal at divers, to simply drop divers in this site and the programme of every 100m or so. Large areas of Seasearch diving in 2005 included the seabed can be quite uniform several sites in the vicinity of the - but how can you tell without disposal ground. This revealed sending a diver down?. some bedrock/large boulder sites, often dominated by small ascidians One answer is to use remote such as Pycnoclavella aurilucens sensing data, such as sidescan and Polycarpa scuba but also or mulitbeam echosounder data. One of the big tasks of 2005 including some impressive ross Such data can be expensive to was to look back over all the coral specimens. gather, but, where it exists, can Seasearch forms produced since be extremely useful in planning 1995, making sure they were dives. correctly entered onto Marine Recorder - the national marine species and habitats database. At the same time, each record was assigned a biotope code from the Joint Nature Conservation Committee (JNCC) Marine Habitat Classification version 04.05. 26 biotope complexes were identified from the data - rocky biotopes Sidescan data from Worbarrow Bay. The were easier to identify as much of main reef running across the bay is clearly the sediment biotopes can only be visible. Close examination also reveals a recognised from the sort of species small wreck (thought to be the Patricia II) lists produced by grab sampling. and parts of the Winfrith pipeline. Much of the requirement for marine In Dorset we have access to three biological data is for the distribution remote sensing datasets: a sidescan and extent of seabed habitats - this survey of Purbeck Marine Wildlife extra step makes the Seasearch Reserve, undertaken by Dorset data much more likely to be widely Wildlife Trust; a sidescan survey used and is a significant move around Durlston Head, undertaken towards producing a seabed habitat The deepening operation is ongoing by Durlston Marine Project and a map for Dorset. at the time of going to press and the multibeam echosounder survey area will be revisited in 2006 to around the Swanage disposal assess the impact. ground, undertaken by CEFAS.

Seasearch in Dorset is co-ordinated by Dorset Wildlife Trust. The project has received funding support from English Nature, Joint Nature Conservation Committee (JNCC) and Heritage Lottery fund useful resource for planning dives the main reef running across and it would be more productive if Worbarrow Bay, and close to the they could be made easily available much-dived Black Hawk. After to club diving officers and other following the reef eastwards for a interested divers, to plan their own while, the divers swam up over the exploratory dives. reef then continued north across As a trial, we have put the sidescan a couple of smaller reefs to a data from the Purbeck Marine patch of duned gravel - to find the Wildlife Reserve on the website, seabed carpeted with the feeding Section of multibeam data from CEFAS tentacles of thousands of gravel showing area of large boulders via the same webGIS as mentioned above. This also includes a tool to sea cucumbers, Neopentadactyla mixta. All of these have been used in extract co-ordinates so that features planning recent Seasearch dives. identified from the sidescan can be In a bid to make these data more dived (currently, this gives a UTM available, Dorset Wildlife Trust co-ordinate, which needs to be is providing access to remote converted to Lat/Long). This will sensing datasets via its website be publicised to Seasearchers on (see below) the Dorset mailing list. As an aid to interpreting the sidescan, we will add an invisible layer depicting Internet access to Seasearch the seabed geology as interpreted data from the sidescan, so that the The larger cucumbers were There is now an interactive map seabed type will appear alongside estimated to be at a density of over on the DWT website showing the the co-ordinates when the map in 50 per square metre, but there were position of Seasearch dives since interrogated. many more juveniles in amongst the larger ones. 1995. This is based on a simple Once this is working smoothly, webGIS - the user can zoom, pan additional datasets will be added. One of the more amusing aspects and interrogate the map, bringing up of this dive was the occasional details of habitat descriptions and explosive defecation of well-fed sea species lists, along with the name Protection at last for cucumbers. of the recorders. Reefs? Seasearch records from Lyme Bay last summer, 2005 Training particularly from the The following training events took Sawtooth Ledges, helped place in 2005 in Dorset: provide the necessary evidence that scallop 23 April Drawing for Seasearch dredging is damaging the reefs. A one-day workshop led by local For largely economic reasons, the artist, Jo Winzar. This was selectively intensity of dredging increased advertised among a small number considerably last year, with damage of regular contributors (but was This will be expanded to include noted within areas previously not a comment on the quality of site sketches, photos and possibly agreed as voluntary exclusion their sketches). The few who did video clips. It is based on PlanWeb areas. Faced with this evidence, attend found it useful in building - a system used by planners in and Southern Sea Fisheries confidence to draw, but felt that it Dorset County Council. Committees are now considering would have been better to have a what action is necessary to protect tutor who was both experienced in www.dorsetwildlife.co.uk/marine/ the reefs of Lyme Bay. teaching drawing and had practical seasearch experience of Seasearch. Seasearch dive organiser‛s Cucumber gardens 30 April Observer Course toolkit in development Seasearch divers in Worbarrow 9 divers took part in the one-day For the past couple of years dive Bay in late May stumbled upon a course. Diving was arranged for organisers in Dorset have been surprising find. The dive started the following day for participants to using sidescan and multibeam on the wreck of the Patricia II - log some qualifying dives. data to help plan Seasearch dives. a small wreck lying just outside These datasets are an extremely 4/5 June Surveyor Course 16 August - Seasearch dive 7 divers took part in a two day Poole Bay – 4 divers course at the Fine Foundation 27 August – Seasearch dive Marine Centre, Bay. Kimmeridge – 4 divers Diving on the second day was from 30 August – Seasearch dive Swanage Pier Poole Bay – 5 divers 18 June Seahorse survey 25 September – Seasearch Neil Garrick-Maidment of the dive Seahorse Trust instructed 10 Swanage – 6 divers divers in techniques for surveying seahorses. This included a fingertip 23 October – Seasearch dive search among the eelgrass beds Swanage cancelled due to bad at Studland. No seahorses were weather found on the day. 2005 Diving The following is a list of organised dives carried out in Dorset, through Dorset WildlifeTrust. In addition to this, Lin Baldock arranged two weekends through the Marine Conservation Society’s Members Dives programme. 16/17 April – Swanage/Poole Bay. Cancelled due to lack of interest 31 April – Kimmeridge. Diving for those on Observer course. 8 divers 14 May Seahorse Survey, with Seahorse Trust, Studland Beach. Postponed due to bad weather 5 June Seasearch Surveyor course Kimmeridge – 10 divers 18 June Seahorse Survey Studland 6 divers 30 June – evening dive Kimmeridge – cancelled due to bad weather 11 July – evening dive Kimmeridge – cancelled due to bad weather 30 July – Seasearch dive Kimmeridge – 5 divers 31 July - Seasearch dive Swanage/Poole Bay. 7 divers 14 August - Seasearch dive Kimmeridge 5 divers