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Temp: Bottom 12°C
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Dive type : Recreational
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Visibility: Bad
Water: Salt
Recent Divers in Kirkkonummi
Dive Profile
- 1. Air
- 10L Steel
270 → 120 bar
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- Average depth: 11.3m
Data provided by EOL.org
Species Identified
Perca fluviatilis Linnaeus, 1758 (European perch)
Perch live in schools, often mixing with other species of fish, usually in the top 50 metres of water. Spawning takes place in April, the very sticky eggs being produced in bands. Females twine these bands around submerged...
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Perch live in schools, often mixing with other species of fish, usually in the top 50 metres of water. Spawning takes place in April, the very sticky eggs being produced in bands. Females twine these bands around submerged vegetation or among rocks while the males follow her and fertilise the eggs. The young fish hatch after about three weeks and remain amongst the egg bands until the yoke sac is exhausted. They then venture into more open water and feed on planktonic animals. As they grow they begin to shoal together close to the bank. Males mature when they reach the length of 7 – 8 cm, females when they are 10 cm.
Mytilus edulis Linnaeus, 1758 (edible blue mussel)
The mussel is a filter-feeder; it filters bacteria, plankton, and detritus from the water . When large beds of this gregarious species form, individuals are bonded together with threads of byssus. Predation is the greatest...
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The mussel is a filter-feeder; it filters bacteria, plankton, and detritus from the water . When large beds of this gregarious species form, individuals are bonded together with threads of byssus. Predation is the greatest cause of mortality; a range of predators take mussels, including dog-whelks (Nucella lapillus), crabs, sea urchins, star-fish, and birds such as the oystercatcher (Haematopus ostralegus) . Although mussels seem fairly defenceless, remarkably they are able to fend off marauding dog whelks and other predatory gastropods; a number of mussels work together to immobilise the predator with bysuss threads . Organisms that attach to mussels, such as seaweeds and barnacles, may increase the risk of the mussel becoming detached by wave action; however, mussels are able to sweep their foot over their shell, which may help to minimise the likelihood of such an organism becoming attached . The sexes are separate, fertilisation occurs externally and spawning peaks in spring and summer . The larval stage is free-swimming and planktonic for around 4 weeks , before settling first on filamentous organisms such as seaweeds . After growing for a while, they detach and drift in the water on a long byssal thread; a mode of dispersal likened to that of young spiders floating through the air on a silk thread . After four weeks or so, the young mussel will have settled again, this time on a mussel bed . Young mussels are thought to have evolved primary settlement on filamentous substrates in order to avoid having to compete with adult mussels . Mussels are host to the pea crab (Pinnotheres pisum), and a copepod (Mytilicola intestinalis), both of which are not parasites, as was once thought, but commensal organisms . Furthermore, mussel beds provide habitats for a variety of marine life, and support higher levels of biodiversity than surrounding mudflats . The biodiversity of the bed increases with its size and age .
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Petri Hirvonen
Finland
Date: 2008-07-20 - 13:20
Max Depth: 15m Duration: 33mins
Dive buddies:
Petri Pajunen
Access to water from stony shore near a cooking shed where we had some snack after the dives. Some European Perch and Mussels.
Clear weather, light winds (aprox. 2 m/s). Air temp. 20°C