Spatial distribution of two solenid bivalves, Solen gordonis Yokoyama, 1920 and S. roseomaculatus Pilsbry, 1901, in a heterogeneous, subtidal soft-bottom area

• Published in: Plankton & benthos research 2024/08/29, Vol.19(3), pp.125-140
• Main Authors: Takeuchi, Seiji, Horii, Ryosuke, Sugita, Kanami, Masumi, Satoshi, Uchida, Jun, Aoshima, Takashi
• Format: Article
• Language: English
• Subjects: feeding morphology; infaunal suspension-feeding bivalve; razor clam; sediment grain size composition; spatial distribution; subtidal soft-bottom area
• ISSN: 1880-8247; 1882-627X
• DOI: 10.3800/pbr.19.125

The two solenid bivalves, Solen gordonis and S. roseomaculatus, are infaunal suspension feeders and commonly cooccur in the same coastal areas of Japan. This study hypothesized that (i) within an area, the two functionally similar and closely related species showed a different microhabitat preference in spatial distribution and (ii) they exhibited a different feeding morphological trait adaptive to a respective preferred environment. Firstly, to reveal the microhabitat preference of the two species, grab sampling of bivalves and sediment samples was made at 49 stations arranged on an approximate 250-m×250-m grid within a heterogeneous, subtidal soft-bottom area (study area: ca. 300 ha) of Sasebo Bay, northwestern Kyushu, Japan. Secondly, to examine the linkage between the spatial distribution patterns and their feeding morphology, the size of gills and labial palps, which are their feeding apparatus, was compared between the two species. The results of the grab sampling showed that the spatial distribution patterns were differed between the species at a local scale, where the main habitat of S. gordonis was located in coarser-grained sediment bottoms than that of S. roseomaculatus. The results of the morphological comparison indicated that the gill fraction of S. gordonis was larger than that of S. roseomaculatus, whereas the palp fraction did not significantly differ between the two species. The interspecific difference in the local distributions might be related in part to the morphological differences in their feeding apparatus. Our findings suggested the importance of feeding morphological traits in understanding the association between the spatial distribution of infaunal suspension-feeding bivalves and sediment grain size composition in coastal soft-bottom habitats.