The occurrence and distribution of Najas flexilis (Slender naiad) in Loch of Craiglush, Loch of the Lowes and Loch of Butterstone

NatureScot

Description

Records from a survey of Najas flexilis (Slender naiad) and associated waterplants from three linked lochs.

This dataset contains zero abundance records for N. flexilis. These were collected as part of a structured survey using the methodology described below

Geographic Description

Perthshire, Scotland

Purpose

The survey was carried out to determine the current status of Najas flexilis (slender naiad) in Loch of Craiglush, Loch of the Lowes and Loch of Butterstone as N. flexilis is a Red Data species. Further impetus to the study was given by the fact that it has been proposed to designate the three lochs as a Special Area of Conservation (SAC) mainly because of the presence of N. flexilis. The need to record the present distribution and occurrence of N. flexilis in the lochs is vitally important to confirm its presence, to justify the lochs' proposed status as an SAC and to aid future monitoring of this species.

Data quality

High: Survey was carried out by an experienced contractor, using approved methodology.

Methods

The perimeter of Loch of Craiglush from the water's edge to approximately 2 m deep, the limit of visibility from the surface, was surveyed by snorkelling and occasional diving using SCUBA Approximately half of the shoreline, to the north, was surveyed in 1994 and the remainder to the south in 1995. A small area was resurveyed in 1996. Part of the area surveyed in 1994 was revisited in 1995 and 1996 allowing inter-year comparisons to be made in the density and occurrence of N. flexilis in that area. An underwater video film was made of area A in 1994. </br>

Loch of the Lowes has been surveyed over a longer period but in a less structured fashion than Craiglush and Butterstone. Only 50% of the shoreline to varying depths of between 1 m to 2.5m have been surveyed, mainly at the eastern end of the loch. Surveys of various sections took place over the three years 1987-1989 and the four years 1993-1996. Surveys were made mainly by snorkelling and occasionally by SCUBA diving.

In Loch of Butterstone, approximately 85% of the perimeter of the loch from the water's edge to the limit of visiblhty from the surface of the water, ranging from 0.5 m to 1 m deep, was surveyed for N. flexilis by snorkelling (only) on six days between 28 August and 19 September 1996. The remaining 15% of the perimeter was unsurveyed due to deteriorating conditions.

Citation

NatureScot ([Insert download year]). The occurrence and distribution of Najas flexilis (Slender naiad) in Loch of Craiglush, Loch of the Lowes and Loch of Butterstone. Occurrence dataset on the NBN Atlas

Rights

OGL

Digitised records