Fusus

Abstract: We investigated growth and grazing rates of the prostomatid ciliate Tiarina fusus when feeding on several species of red-tide and/or toxic algae (RTA). T. fusus ingested the dinoflagellates Lingulodinium polyedrum, Scrippsiella trochoidea, Heterocapsa triquetra, Prorocentrum minimum, Amphidinium carterae, and the raphidophyte Heterosigma akashiwo, but rarely consumed the dinoflagellate Ceratium fusus, and did not feed on the dinoflagellate Prorocentrum micans. T. fusus exhibited positive growth on L. polyedrum, S. trochoidea, and H. akashiwo. Specific growth rates of T. fusus increased rapidly with increasing density of L. polyedrum, S. trochoidea, and H. akashiwo before saturating between 500 and 1000 ng C ml -1 . Maximum specific growth rate of T. fusus feeding on L. polyedrum (0.47 d -1 ) was much higher than when feeding on S. trochoidea (0.13 d -1 ) or H. akashiwo (0.10 d -1 ). Threshold prey concentrations (where net growth = 0) for L. polyedrum, S. tro- choidea, and H. akashiwo were 34 to 160 ng C ml -1 . Maximum ingestion rates of T. fusus on L. poly- edrum, S. trochoidea, and H. akashiwo were 23.4, 10.2, and 6.5 ng C predator -1 d -1 , respectively, while maximum clearance rates were 4.5, 0.2, and 0.6 µl predator -1 h -1 , respectively. T. fusus exhib- ited comparable or higher maximum growth, ingestion, and clearance rates than previously reported for the mixotrophic dinoflagellate Fragilidium cf. mexicanum or the heterotrophic dinoflagellates Protoperidinium cf. divergens and P. crassipes, when grown on the same prey species. Grazing coefficients calculated by combining field data on abundances of T. fusus and co-occurring RTA with laboratory data on ingestion rates obtained in the present study suggest that T. fusus sometimes has a considerable grazing impact on the populations of H. akashiwo.

Abstract: The seasonal abundance of the dominant dinoflagellate, Ceratium fusus, was investigated from January 2000 to December 2003 in a coastal region of Sagami Bay, Japan. The growth of this species was also examined under laboratory conditions. In Sagami Bay, C. fusus increased significantly from April to September, and decreased from November to February, though it was found at all times through out the observation period. C. fusus increased markedly in September 2001 and August 2003 after heavy rainfalls that produced pycnoclines. Rapid growth was observed over a salinity range of 24 to 30, with the highest specific rate of 0.59 d−1 measured under the following conditions: salinity 27, temperature 24°C, photon irradiance 600 µmol m−2s−1. The growth rate of C. fusus increased with increasing irradiance from 58 to 216 µmol m−2s−1, plateauing between 216 and 796 µmol m−2s−1 under all temperature and salinity treatments (except at a temperature of 12°C). Both field and laboratory experiments indicated that C. fusus has the ability to grow under wide ranges of water temperatures (14–28°C), salinities (20–34), and photon irradiance (50–800 µmol m−2s−1); it is also able to grow at low nutrient concentrations. This physiological flexibility ensures that populations persist when bloom conditions come to an end.

Abstract: Priority and synonymy of the name to be used for the family usually known as Cymatiidae are discussed. Names adopted are Family Ranellidae Gray, 1854 and subfamilies Ranellinae Gray, 1854, Cymatiinae Iredale, 1913 (1891) (conserved under ICZN Article 40b), and Personinae Gray, 1854. A neotype designated for Buccinum caudatum Gmelin, 1791 stabilises this as the valid name for the species commonly known as Linatella (Linatella) cingulata (Lamarck, 1822). Other synonyms are Fusus cutaceus Lamarck, 1816; Triton undosum Kiener, 1842; Triton rostratus “Martini” Morch, 1852; Triton poulsenii Morch, 1877; Purpura bantamensis Martin, 1899; Cymatium (Linatella) krenkeli Cox, 1930; Cymatium (Linatella) floridanum Mansfield, 1930; C. cingulatum peninsulum M. Smith, 1937; and Linatella neptunia Garrard, 1963. The first present-day specimen is recorded from eastern Northland, New Zealand where, however, L. caudata occurred commonly during late Pleistocene time. A lectotype designated for Triton cynocephalum La...

Abstract: To examine the population development of the dinoflagellates, Ceratium furca and Ceratium fusus, daily field monitoring was conducted between April and July 2003 in the temperate coastal water of Sagami Bay, Japan. During the study period, the concentrations of C. furca were always lower than those of C. fusus. A sharp increase in the densities of both species was recorded on 5 May showing the maximum cell concentrations (C. furca = 14,800 cells L-1, C. fusus = 49,600 cells L-1). In the 7 days prior to the May bloom of the Ceratium species (29 April to 1 May), the highest density of the heterotrophic dinoflagellate Noctiluca scintillans was observed. Additionally, a second bloom of C. fusus occurred on 22 July. Here, two causes of the significant increases in the Ceratium populations during the two blooming periods (first time; 1 to 8 May, second time; 15 to 22 July) are presented. First, an increase in the nutrients of the surface layer regenerated by the breakdown of blooms by N.scintillans could be considered as a major cause of the population increase of the two Ceratium species. Second, a decrease in salinity (to 27 psu) was correlated with the later bloom ofC. fusus. These results suggest that the population development of the two Ceratium species requires nutrients regenerated after the reduction of the diatom population byN. scintillans and, forC. fusus, continuous low salinity conditions, compared to other environmental factors during the rainy season. Key words: Ceratium furca; Ceratium fusus; Noctiluca scintillans; Bloom process; Environmental factor