Abundance of Naked Amoebae in Sediments of Hiroshima Bay, Seto Inland Sea of Japan

Abstract

The present paper provides the first data on naked amoebae from sediments of Hiroshima Bay. Three stations in the inner part of the bay were sampled over a three‐month period. Abundance of naked amoebae ranged from 1,019 to 45,561 cells/g dry sediment. Results indicate: (i) surface sediment populations in most cases were higher than subsurface populations; (ii) there was some evidence of temporal variation with counts generally increasing from March to May: and (iii) the site located near Hiroshima City had fewer amoebae on several occasions than the other two sites. There was a negative exponential relationship between acid‐volatile sulfide concentration and abundance of amoebae. Most amoebae were small with the average size ranging from 6.6–14 μm. Morphotype 1, amoebae that extend lobose pseudopodia or subpseudopodia during normal locomotion, were dominant (40–100% of enumerated amoebae). Morphotypes 2 and 3 (limax amoebae) were found in lower numbers than the other two morphotypes. The proportion of amoebae occupied by Morphotype 4 (fan‐shaped or discoidal‐flattened amoebae) was higher at a lower total abundance.

High Numbers of Naked Amoebae in the Planktonic Waters of a Mangrove Stand in Southern Florida, USA

“…Moreover, the results suggest that the densities of marine amoebae given in other studies using the aliquot enumeration method (e.g. Anderson 1998; Anderson and Rogerson 1995; Butler and Rogerson 1995; Decamp et al 1999; Mayes et al 1998) are probably within a factor of two of the correct density. This is an important finding since cultivation techniques are often criticized for severely underestimating the size of protozoan populations.…”

“…A series of recent papers has highlighted the numerical importance of heterotrophic naked amoebae (gymnamoebae sensu Page 1983) in marine systems from different geographic regions throughout the world (e.g. Anderson 1998; Anderson and Rogerson 1995; Butler and Rogerson 1995; DeCamp et al 1999; Mayes et al 1998; Rogerson 1991; Rogerson and Laybourn‐Parry 1992). In the plankton of temperate coastal regions, several thousand amoebae are typically found per liter of water (Rogerson and Laybourn‐Parry 1992) suggesting that they play an important, albeit undefined, ecological role in the plankton.…”

Protozoans and Meiofauna Inhabiting a Bead Filter: A Preliminary Investigation of Their Role as Potential Bioindicators of Shrimp Production System Health

“…Naked amoebas were abundant during parts of the grow‐out period and may play a significant role in the removal of substrate‐associated bacteria or algae (Fig. 2D), provided their populations reach a certain minimum threshold density, such as those reported in marine sediment (Decamp et al 1999b) or artificial wetlands (Decamp et al 1999a). Flagellates were present in the PBF, sometimes in large numbers, and included dinoflagellates, small flagellates (<5 μm), and large flagellates, such as the microflagellates previously reported in eutrophic marine environments (Decamp et al 2000).…”