A life strategy optimally geared to living in a stable habitat with a high level of interspecific competition. Parental care is facilitated by low fecundity (small litters of large size offspring), by longevity and size. K-strategists are unlikely to be well adapted to recover from population densities significantly below their equilibrium level and may become extinct if depressed to such low levels (from Baretta-Bekker et al.
, 1992). Cf. r-strategy.
A group of large brown algae of the Order Laminariales, common in the sublittoral fringe and infralittoral zone (q.v.).
A belt of the upper infralittoral (q.v.) subzone on hard substrata, dominated by Laminariales sufficiently dense to form an almost continuous canopy.
A belt of the lower infralittoral (q.v.) subzone on hard substrata, which has scattered Laminariales whose fronds do not meet to form a dense canopy.
A species which, through its predatory activities (for instance, grazing by sea urchins) or by mediating competition between prey species (for instance, by eating sea urchins), maintains community composition and structure. Removal of a keystone species leads to rapid, cascading changes in the structure they support (based on Raffaelli & Hawkins, 1996). The term is also applied here to species which provide a distinctive habitat (for instance a bed of the horse mussel Modiolus modiolus
, or kelp plants Laminaria hyperborea
) and whose loss would therefore lead to the disappearance of the associated community.
A unit of speed used in navigation, being one nautical mile (q.v.) per hour, equating to approximately 0.5 metres per second.