Growth lines in bivalve mollusks have been thought to reflect solar days, circadian rhythms and/or tides. Tides seem to be the dominating influence in some intertidal species. This study provides laboratory evidence suggesting that tides are a major influence in the number of growth lines in the clam Protothaca staminea.
Clams were grown under 4 different \"tidal\" regimes, (0, 1, 2 and 3 tides per day) for forty-one days. Acetate peels of shell cross sections were used for growth line counting. Photomicrographs and measurements showed a striking difference in the growth and number of growth lines between the 4 tidal groups. Generally, those with the least number of tidal emersions showed the least number of lines. Presence of lines in specimens grown with no tidal exposure suggests that in P. staminea the lines may be endogenously controlled but entrained by the tides.
","abstract_html":"<p>Growth lines in bivalve mollusks have been thought to reflect solar days, circadian rhythms and/or tides. Tides seem to be the dominating influence in some intertidal species. This study provides laboratory evidence suggesting that tides are a major influence in the number of growth lines in the clam Protothaca staminea.</p> <p>Clams were grown under 4 different "tidal" regimes, (0, 1, 2 and 3 tides per day) for forty-one days. Acetate peels of shell cross sections were used for growth line counting. Photomicrographs and measurements showed a striking difference in the growth and number of growth lines between the 4 tidal groups. Generally, those with the least number of tidal emersions showed the least number of lines. Presence of lines in specimens grown with no tidal exposure suggests that in P. staminea the lines may be endogenously controlled but entrained by the tides.</p>","abstract_has_math":false,"creators":["Irsula, Orlando"],"institution":null,"degree_name":"Master of Arts (MA)","degree_level":"Thesis","degree_discipline":"Biology","degree_department":null,"school":null,"contributors":["Conrad D. Clausen","Ariel A. Roth","Raymond E. Rychman"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":1981,"date_issued":"1981-05-01T07:00:00Z","date_published":"1981-05-01T07:00:00Z","updated_at":"2026-07-24T02:54:01Z","subjects":["Biology","Terrestrial and Aquatic Ecology","Clams; Tide pool ecology"],"languages":["English"],"rights":["This title appears here courtesy of the author, who has granted Loma Linda University a limited, non-exclusive right to make this publication available to the public. The author retains all other copyrights."],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"https://scholarsrepository.llu.edu/etd/1036","outbound_label":"Repository record","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Conrad D. Clausen","Ariel A. Roth","Raymond E. Rychman"]},{"key":"dc:creator","label":"Author","values":["Irsula, Orlando"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"thesis:degree_discipline","label":"Discipline","values":["Biology"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Thesis"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Master of Arts (MA)"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Biology","Terrestrial and Aquatic Ecology","Clams; Tide pool ecology"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["English"]},{"key":"dc:rights","label":"Dc Rights","values":["This title appears here courtesy of the author, who has granted Loma Linda University a limited, non-exclusive right to make this publication available to the public. The author retains all other copyrights."]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["https://scholarsrepository.llu.edu/etd/1036"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["Growth lines in bivalve mollusks have been thought to reflect solar days, circadian rhythms and/or tides. Tides seem to be the dominating influence in some intertidal species. This study provides laboratory evidence suggesting that tides are a major influence in the number of growth lines in the clam Protothaca staminea.
Clams were grown under 4 different \"tidal\" regimes, (0, 1, 2 and 3 tides per day) for forty-one days. Acetate peels of shell cross sections were used for growth line counting. Photomicrographs and measurements showed a striking difference in the growth and number of growth lines between the 4 tidal groups. Generally, those with the least number of tidal emersions showed the least number of lines. Presence of lines in specimens grown with no tidal exposure suggests that in P. staminea the lines may be endogenously controlled but entrained by the tides.
"]},{"key":"dc:title","label":"Title","values":["Effect of Simulated Tidal Patterns on Growth and Growth Line Formation in the Little Neck Clam, PROTOTHACA STAMINEA"]}]}],"canonical_facts":{"dc:contributor":["Conrad D. Clausen","Ariel A. Roth","Raymond E. Rychman"],"dc:creator":["Irsula, Orlando"],"dc:description.abstract":["Growth lines in bivalve mollusks have been thought to reflect solar days, circadian rhythms and/or tides. Tides seem to be the dominating influence in some intertidal species. This study provides laboratory evidence suggesting that tides are a major influence in the number of growth lines in the clam Protothaca staminea.
Clams were grown under 4 different \"tidal\" regimes, (0, 1, 2 and 3 tides per day) for forty-one days. Acetate peels of shell cross sections were used for growth line counting. Photomicrographs and measurements showed a striking difference in the growth and number of growth lines between the 4 tidal groups. Generally, those with the least number of tidal emersions showed the least number of lines. Presence of lines in specimens grown with no tidal exposure suggests that in P. staminea the lines may be endogenously controlled but entrained by the tides.
"],"dc:identifier":["https://scholarsrepository.llu.edu/etd/1036"],"dc:language":["English"],"dc:rights":["This title appears here courtesy of the author, who has granted Loma Linda University a limited, non-exclusive right to make this publication available to the public. The author retains all other copyrights."],"dc:subject":["Biology","Terrestrial and Aquatic Ecology","Clams; Tide pool ecology"],"dc:title":["Effect of Simulated Tidal Patterns on Growth and Growth Line Formation in the Little Neck Clam, PROTOTHACA STAMINEA"],"thesis:degree_discipline":["Biology"],"thesis:degree_level":["Thesis"],"thesis:degree_name":["Master of Arts (MA)"]},"updated_at":"2026-07-24T02:54:01Z"}