Biodiversity & Conservation

Potamogeton pectinatus community



Image Martin Isaeus - A bed of fennel pondweed Potamogeton pectinatus.
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Distribution map

SS.IMU.Ang.A12 recorded (dark blue bullet) and expected (light blue bullet) distribution in Britain and Ireland (see below)

  • EC_Habitats
  • UK_BAP

Recorded distribution in Britain and Ireland

Recorded from isolated saline lagoons in Shetland, Orkney and the Outer Hebrides.

Habitat preferences

Temperature range preferences - Data deficient

Water clarity preferences - High clarity / Low turbidity
Medium clarity / Medium turbidity
Low clarity / High turbidity

Limiting Nutrients - Nitrogen (nitrates)
Phosphorus (phosphates)

Other preferences - None known.

Additional information

Marine records of this biotope are restricted to Scottish saline lagoons (JNCC, 1999) but the equivalent NVC A12 community is characteristic of still to quite fast moving and often enriched, polluted and turbid eutrophic waters. NVC A12 is widely distributed in the warmer lowland waters of southern Britain with sporadic records in west and north Britain. NVC A12 has become increasingly common in pools, canals, ditches and streams contaminated by agricultural and industrial effluents (Rodwell, 1995).

Habitat preferences

  • Potamogeton pectinatus is restricted to habitats either permanently submerged or emersed for only 1-3 months.
  • Potamogeton pectinatus grows down to 10m but optimal growth was reported at 7cm to 6m in depth, although the depth at which Potamogeton pectinatus survives in dependant on wave action, turbulence, turbidity and hence the substrata type.
  • Potamogeton pectinatus grows on a variety of substrata depending on wave action, e.g. clays, muds, sands, gravels, peats, rubble or bedrock.
  • Potamogeton pectinatus is characteristic of persistently alkaline waters of pH 7-9 but absent from water below pH 6.3 or above pH 10.7 (Kantrud, 1990).
  • Potamogeton pectinatus and Potamogeton filiformis are the only Potamogeton species to penetrate brackish water. Potamogeton pectinatus grows optimally between 5-14g/l in brackish waters with a maximum salinity tolerance of 8ppt Cl¯ (ca 15psu). It grows well below 4 ppt Cl¯ (ca 7.25psu) but is replaced by Ruppia dominated communities above 9 ppt Cl¯ (ca 16.25 psu), forming mixed stands at intermediate salinities (see IMS.Rup).
  • Potamogeton pectinatus is characteristic of polluted, oxygen poor waters with high N or P levels but becomes less competitive at low P levels and probably requires Ca and Mg.
  • Fennel pondweed is tolerant of moderate to fast current flows but this biotope occurs in very weak tidal streams in extremely to ultra wave sheltered lagoons.
Details from Verhoeven & van Vierssen (1978), Verhoeven (1980a), Kantrud (1990) Preston (1995) and JNCC (1999). Detailed accounts of the physical and chemical tolerance of Potamogeton pectinatus in fresh and saline waters and sediments are given by Haslam (1978), Kantrud (1990) and Preston (1995).

This review can be cited as follows:

Tyler-Walters, H. 2002. Potamogeton pectinatus community. Marine Life Information Network: Biology and Sensitivity Key Information Sub-programme [on-line]. Plymouth: Marine Biological Association of the United Kingdom. [cited 27/11/2015]. Available from: <>