Limaria hians (Mollusca: Limacea): a neglected reef-forming keystone species

Abstract

1. The case is made for recognition of the marine bivalve Limaria hians as a reef-forming species, which plays a key architectural role in certain benthic communities around the United Kingdom and Ireland. 2. This species uses byssal threads to construct nests that can coalesce to form reefs that cover hectares of seabed, contain multiple conspecifics and bind sediment. In so doing, L. hians modifies physical, chemical and biological processes at the sediment-water interface. 3. Such nests support a high diversity of associated organisms in coarse-grade sediments (19 species of algae and 265 species of invertebrates from six discrete nests in Loch Fyne are reported on), although the biological interactions between species both inside and outside this assemblage (e.g. predatory cod) are unknown. 4. Being insubstantial, labyrinthine structures situated on the sediment surface, Limaria nests are sensitive to mechanical impacts, such as those caused by moorings, hydraulic dredging for infaunal bivalves and scallop dredging. 5. At appropriate sites, the status of L. hians can contribute a useful indication of disturbance on coarse-grade sediments.

Community composition and diversity of twoLimaria hians(Mollusca: Limacea) beds on the west coast of Scotland

“…This is probably unsurprising considering their close geographical locations. Interestingly approximately 43% of the species found in the Loch Fyne study (Hall-Spencer & Moore, 2000b) were also found on the L. hians beds in this investigation; however, the composition of the benthos was quite different. Molluscs dominated the Loch Fyne samples (N = 74) followed by Crustacea (N = 63) and Polychaeta (N = 52).…”

“…This study represents the first comprehensive quantitative examination of the associated community found in a L. hians bed. A qualitative study in Loch Fyne on the west coast of Scotland recorded more than 280 taxa from 6 L. hians nests (Hall-Spencer & Moore, 2000b). Although the total number of species recorded in the present investigation was virtually identical to the Loch Fyne study, a maximum of 227 taxa were found at a single site (Shian) when data from both the summer and winter sampling periods were pooled.…”

“…Interestingly a concurrent study (Trigg et al , unpublished) found that when cages containing L. hians nest material were brought to the surface, every gallery (>70) contained one or more F. affinis . Hall-Spencer & Moore (2000b) propose that F. affinis could be a commensal inhabitant of L. hians nests and future work should investigate whether a possible relationship exists between these species.…”

“…Following these or anthropogenic impacts the disturbed community may be significantly different from the community found on the original bed. The disturbed community possibly consisting of a less diverse assemblage, with opportunistic species taking advantage of the dislodged material and an increase in epifaunal scavengers, such as juvenile Gadus morhua , as food becomes available (Hall, 1994; Kaiser & Spencer, 1994; Hall-Spencer & Moore, 2000b). Over time it is thought that the community will establish a group of organisms partly typifying the adjacent environment in addition to some characteristic species for the surrounding habitat.…”

Community composition and diversity of twoLimaria hians(Mollusca: Limacea) beds on the west coast of Scotland

“…This is probably unsurprising considering their close geographical locations. Interestingly approximately 43% of the species found in the Loch Fyne study (Hall-Spencer & Moore, 2000b) were also found on the L. hians beds in this investigation; however, the composition of the benthos was quite different. Molluscs dominated the Loch Fyne samples (N = 74) followed by Crustacea (N = 63) and Polychaeta (N = 52).…”

“…This study represents the first comprehensive quantitative examination of the associated community found in a L. hians bed. A qualitative study in Loch Fyne on the west coast of Scotland recorded more than 280 taxa from 6 L. hians nests (Hall-Spencer & Moore, 2000b). Although the total number of species recorded in the present investigation was virtually identical to the Loch Fyne study, a maximum of 227 taxa were found at a single site (Shian) when data from both the summer and winter sampling periods were pooled.…”

“…Interestingly a concurrent study (Trigg et al , unpublished) found that when cages containing L. hians nest material were brought to the surface, every gallery (>70) contained one or more F. affinis . Hall-Spencer & Moore (2000b) propose that F. affinis could be a commensal inhabitant of L. hians nests and future work should investigate whether a possible relationship exists between these species.…”

“…Following these or anthropogenic impacts the disturbed community may be significantly different from the community found on the original bed. The disturbed community possibly consisting of a less diverse assemblage, with opportunistic species taking advantage of the dislodged material and an increase in epifaunal scavengers, such as juvenile Gadus morhua , as food becomes available (Hall, 1994; Kaiser & Spencer, 1994; Hall-Spencer & Moore, 2000b). Over time it is thought that the community will establish a group of organisms partly typifying the adjacent environment in addition to some characteristic species for the surrounding habitat.…”

Molecular Phylogeny and Morphological Distinctions of Two Popular Bivalves,Ctenoides scaberandCtenoides mitis

“…For example, a diverse spectrum of visual abilities can be found in the family, ranging from eyeless (Limaria) to pit eyes (Lima) to closedlens eyes (Ctenoides) [29][30][31]. Members of the family also show distinct defense mechanisms, including nest-building behavior [20], swimming, tentacle autotomy [14,18,20,21], and, potentially, defensive chemicals [30]. The evolution of these traits cannot be addressed without a comprehensive phylogeny.…”

Community composition and diversity of twoLimaria hians(Mollusca: Limacea) beds on the west coast of Scotland

“…This is probably unsurprising considering their close geographical locations. Interestingly approximately 43% of the species found in the Loch Fyne study (Hall-Spencer & Moore, 2000b) were also found on the L. hians beds in this investigation; however, the composition of the benthos was quite different. Molluscs dominated the Loch Fyne samples (N = 74) followed by Crustacea (N = 63) and Polychaeta (N = 52).…”

“…This study represents the first comprehensive quantitative examination of the associated community found in a L. hians bed. A qualitative study in Loch Fyne on the west coast of Scotland recorded more than 280 taxa from 6 L. hians nests (Hall-Spencer & Moore, 2000b). Although the total number of species recorded in the present investigation was virtually identical to the Loch Fyne study, a maximum of 227 taxa were found at a single site (Shian) when data from both the summer and winter sampling periods were pooled.…”

“…Interestingly a concurrent study (Trigg et al , unpublished) found that when cages containing L. hians nest material were brought to the surface, every gallery (>70) contained one or more F. affinis . Hall-Spencer & Moore (2000b) propose that F. affinis could be a commensal inhabitant of L. hians nests and future work should investigate whether a possible relationship exists between these species.…”

“…Following these or anthropogenic impacts the disturbed community may be significantly different from the community found on the original bed. The disturbed community possibly consisting of a less diverse assemblage, with opportunistic species taking advantage of the dislodged material and an increase in epifaunal scavengers, such as juvenile Gadus morhua , as food becomes available (Hall, 1994; Kaiser & Spencer, 1994; Hall-Spencer & Moore, 2000b). Over time it is thought that the community will establish a group of organisms partly typifying the adjacent environment in addition to some characteristic species for the surrounding habitat.…”

Molecular Phylogeny and Morphological Distinctions of Two Popular Bivalves,Ctenoides scaberandCtenoides mitis

“…For example, a diverse spectrum of visual abilities can be found in the family, ranging from eyeless (Limaria) to pit eyes (Lima) to closedlens eyes (Ctenoides) [29][30][31]. Members of the family also show distinct defense mechanisms, including nest-building behavior [20], swimming, tentacle autotomy [14,18,20,21], and, potentially, defensive chemicals [30]. The evolution of these traits cannot be addressed without a comprehensive phylogeny.…”

Community composition and diversity of twoLimaria hians(Mollusca: Limacea) beds on the west coast of Scotland

“…This is probably unsurprising considering their close geographical locations. Interestingly approximately 43% of the species found in the Loch Fyne study (Hall-Spencer & Moore, 2000b) were also found on the L. hians beds in this investigation; however, the composition of the benthos was quite different. Molluscs dominated the Loch Fyne samples (N = 74) followed by Crustacea (N = 63) and Polychaeta (N = 52).…”

“…This study represents the first comprehensive quantitative examination of the associated community found in a L. hians bed. A qualitative study in Loch Fyne on the west coast of Scotland recorded more than 280 taxa from 6 L. hians nests (Hall-Spencer & Moore, 2000b). Although the total number of species recorded in the present investigation was virtually identical to the Loch Fyne study, a maximum of 227 taxa were found at a single site (Shian) when data from both the summer and winter sampling periods were pooled.…”

“…Interestingly a concurrent study (Trigg et al , unpublished) found that when cages containing L. hians nest material were brought to the surface, every gallery (>70) contained one or more F. affinis . Hall-Spencer & Moore (2000b) propose that F. affinis could be a commensal inhabitant of L. hians nests and future work should investigate whether a possible relationship exists between these species.…”

“…Following these or anthropogenic impacts the disturbed community may be significantly different from the community found on the original bed. The disturbed community possibly consisting of a less diverse assemblage, with opportunistic species taking advantage of the dislodged material and an increase in epifaunal scavengers, such as juvenile Gadus morhua , as food becomes available (Hall, 1994; Kaiser & Spencer, 1994; Hall-Spencer & Moore, 2000b). Over time it is thought that the community will establish a group of organisms partly typifying the adjacent environment in addition to some characteristic species for the surrounding habitat.…”

Molecular Phylogeny and Morphological Distinctions of Two Popular Bivalves,Ctenoides scaberandCtenoides mitis

“…For example, a diverse spectrum of visual abilities can be found in the family, ranging from eyeless (Limaria) to pit eyes (Lima) to closedlens eyes (Ctenoides) [29][30][31]. Members of the family also show distinct defense mechanisms, including nest-building behavior [20], swimming, tentacle autotomy [14,18,20,21], and, potentially, defensive chemicals [30]. The evolution of these traits cannot be addressed without a comprehensive phylogeny.…”