File:American malacological bulletin (1987) (18130166076).jpg

Title: American malacological bulletin
Identifier: americanmal4519861987amer (find matches)
Year: 1983 (1980s)
Authors: American Malacological Union
Subjects: Mollusks; Mollusks
Publisher: (Hattiesburg, Miss. ?) : (American Malacological Union)
Contributing Library: Smithsonian Libraries
Digitizing Sponsor: Biodiversity Heritage Library

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282 AMER. MALAC. BULL. 5(2) (1987)
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Fig. 1. Map of the Fiji Islands with collecting areas where interstitial molluscs were collected designated by arrows. sands or fluctuating salinities. Whenever one species of interstitial mollusc was found and if the schedule allowed, more samples were taken from that locality. Cores of sand approximately 10 cm high and 5 cm wide were collected with a garden trowel and individually placed in plastic bags. Sub- tidal samples were collected in about 1 m of water near the edge of Suva Reef. All samples were transported back to the laboratory of the Institute of Marine Resources at the Univer- sity of the South Pacific in Suva where living organisms were extracted by elutriation, photographed, studied and fixed in 70% alcohol or Hollande's fixative. Although numerous areas were sampled at any one locality, only those where interstitial molluscs were found are reported. DESCRIPTION OF COLLECTING SITES Suva reef is a fringing reef at the outer portion of the delta of the Rewa River. Interstitial molluscs were found there in two habitats. One site was a series of small pockets just inside the algal ridge. These holes were about 0.5 m in depth and often strewn with calcareous sand; they harbored holothurians that break down the chunks of coral into smaller particles. Coarse sand was often banked on the most pro- tected side of the hole. Fine sediments were absent. Water in the holes is continuously exchanged by surge at low tide and the entire area is covered at high tide. The other habitat for interstitial molluscs was along the edge of the channel through the reef. In this passage the surge from wave action is continual and the coarser sand is located along the chan- nel edge. Extensive sampling in the great expanses of sand substratum behind the reef did not yield any interstitial molluscs. This habitat may be unsuitable owing to freshwater intrusion during severe rains. On one occasion, 20 cm of rain was recorded in 24 hr and mud suspended in freshwater runoff from the Rewa River was seen to extend all along the shore side of the reef. Interstitial molluscs were found in sand from three islands near Viti Levu: Nananu-i-ra off the northeast coast, and Mana Island and the Yasawa Group off the northwest coast. At Nananu-i-ra, coarse sand samples collected from around the bases of dock pilings yielded interstitial molluscs. At all sites the sand was taken from low intertidal regions near the fringing reefs or from subtidal habitats. Numerous samples were collected at Korolevu, a resort area on the mid-south shore of Viti Levu where a fring- ing coral reef is located very close to the shoreline (Fig. 2). First suggested as a likely place for interstitial fauna by Pro- fessor John Ryland (pers. comm.), the beach is located land- ward of an inlet in the fringing reef, with a relatively deep off- shore channel leading up to the beach. An intermittent stream flows into the inlet from the surrounding hills. Although pro- tected, the area is continually washed by waves and is therefore considered as a high-energy beach.

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