4
P. Tett
1.3 The Ecosystem in Loch Creran
The west coast of Scotland is cleft in many places with long arms of the sea. Called
loch in Scots Gaelic (with the final ch a soft sound made in the back of the mouth),
most are technically fjords: river valleys internally deepened by glaciers during the
Ice Age and then flooded with salt water as the level of the ocean rose when the
main ice sheets melted. For several millennia, these sheltered sea-lochs have provided highways and food sources to the people who lived in this otherwise unproductive and mountainous region. Now they are both a tourist attraction and a site
for fish-farming, especially Atlantic salmon and mussels.
Halfway up this coast, the large fjord of the Firth of Lorne runs north-eastwards,
along the line of the Great Glen fault that separates two ancient tectonic plates and
continues to shake us locals with mini-earthquakes about once a decade. Big fjords
often have little fjords, made by tributary glaciers, and the Firth of Lorne is no
exception: loch Spelve, on the island of Mull, and on the mainland side, lochs Eil,
Linnhe, Leven, Creran, Etive, Feochan and Craignish. All these have the characteristic feature of a fjord: a narrow and shallow entrance, with at least one deeper and
wider basin inside. My friend Anton Edwards once wrote that although there is no
such thing as a typical sea-loch, if you make lists of the Scottish saltwater lochs
ranked in terms of their physical attributes, such as greatest depth, or freshwater
inflow from the rivers discharging to their heads, then Creran comes close to the
middle of most lists.
Seem from the top of a nearby hill, Creran looks like a lake: the winding channel that connects it to the Firth of Lorne is hidden behind a wooded hill (Fig. 1.1).
0 m
20 m
50 m
8
0
4
2
6
1 0
kilometres
light, fresh
(b)
B
B
C
B
C
A
A
flood tide
ebb tide
dense, salty
A
C
(a)
Fig. 1.1 A Scottish site for aquaculture: (a) sketch of loch Creran, looking west towards the larger
fjord of the Firth of Lorne; (b) section, showing density and deduced circulation
P. Tett
1.3 The Ecosystem in Loch Creran
The west coast of Scotland is cleft in many places with long arms of the sea. Called
loch in Scots Gaelic (with the final ch a soft sound made in the back of the mouth),
most are technically fjords: river valleys internally deepened by glaciers during the
Ice Age and then flooded with salt water as the level of the ocean rose when the
main ice sheets melted. For several millennia, these sheltered sea-lochs have provided highways and food sources to the people who lived in this otherwise unproductive and mountainous region. Now they are both a tourist attraction and a site
for fish-farming, especially Atlantic salmon and mussels.
Halfway up this coast, the large fjord of the Firth of Lorne runs north-eastwards,
along the line of the Great Glen fault that separates two ancient tectonic plates and
continues to shake us locals with mini-earthquakes about once a decade. Big fjords
often have little fjords, made by tributary glaciers, and the Firth of Lorne is no
exception: loch Spelve, on the island of Mull, and on the mainland side, lochs Eil,
Linnhe, Leven, Creran, Etive, Feochan and Craignish. All these have the characteristic feature of a fjord: a narrow and shallow entrance, with at least one deeper and
wider basin inside. My friend Anton Edwards once wrote that although there is no
such thing as a typical sea-loch, if you make lists of the Scottish saltwater lochs
ranked in terms of their physical attributes, such as greatest depth, or freshwater
inflow from the rivers discharging to their heads, then Creran comes close to the
middle of most lists.
Seem from the top of a nearby hill, Creran looks like a lake: the winding channel that connects it to the Firth of Lorne is hidden behind a wooded hill (Fig. 1.1).
0 m
20 m
50 m
8
0
4
2
6
1 0
kilometres
light, fresh
(b)
B
B
C
B
C
A
A
flood tide
ebb tide
dense, salty
A
C
(a)
Fig. 1.1 A Scottish site for aquaculture: (a) sketch of loch Creran, looking west towards the larger
fjord of the Firth of Lorne; (b) section, showing density and deduced circulation