Biodiversity & Conservation

Hartlaubella gelatinosa and Conopeum reticulum on low salinity infralittoral mixed substrata


<i>%Hartlaubella gelatinosa%</i> and <i>%Conopeum reticulum%</i> on low salinity infralittoral mixed substrata
Distribution map

IR.SIR.EstFa.HarCon recorded (dark blue bullet) and expected (light blue bullet) distribution in Britain and Ireland (see below)

  • EC_Habitats

Species indicative of sensitivity

To assess the sensitivity of the biotope, the sensitivity of component species is reviewed. Those species that are considered to be particularly indicative of the sensitivity of the biotope, and for which research has been undertaken in detail are shown below (see selection criteria). The biology of other component species of the biotope is also taken into account wherever information is known to the researcher.

Species found especially in this biotope

  • Hartlaubella gelatinosa
  • Conopeum reticulum
  • Bowerbankia imbricata

Rare of scarce species associated with this biotope

Community Importance Species name Common Name
Key structural Hartlaubella gelatinosa A hydroid
Key structural Balanus crenatus An acorn barnacle
Important characterizing Conopeum reticulum A bryozoan


This biotope is characterized by a encrusting bryozoan and hydroid turf. Hydroids such as Hartlaubella gelatinosa, Obelia longissima and Obelia dichotoma are important space occupying species, that modify the substratum with respect to recruitment in other species, e.g. Balanus crenatus. and whose loss may result in degradation of the community. Therefore, the characterizing species Hartlaubella gelatinosa has been included as key structuring. However, in the absence of a full key information review on the species reference was made to key information reviews of Cordylophora caspia and Nemertesia ramosa, together with reviews of hydroid biology. Balanus crenatus also modifies the substratum and adds complexity to the community and has been included as key structuring, since its loss from similar communities has been shown to result in loss of the associated community. Conopeum reticulum has been included as important characterizing, since its loss would probably result in loss of the biotope. Sediment dwelling polychaetes are probably at the extreme limit of their salinity tolerance within the biotope and their loss would not result in loss, or re-identification of the biotope. Therefore, the effects of factors on polychaetes is not considered indicative of biotope sensitivity.

Additional information

This biotope is relatively impoverished and the community is restricted to brackish water tolerant species. Only 14 species were recorded within this biotope (Hiscock & Moore, 1986; JNCC, 1999).

This review can be cited as follows:

Tyler-Walters, H. 2002. Hartlaubella gelatinosa and Conopeum reticulum on low salinity infralittoral mixed substrata. Marine Life Information Network: Biology and Sensitivity Key Information Sub-programme [on-line]. Plymouth: Marine Biological Association of the United Kingdom. [cited 30/11/2015]. Available from: <>