GROWTH OF THE GREEN ALGA CODIUM FRAGILE IN A CONNECTICUT ESTUARY¹

Abstract

SUMMARY An in situ comparison of environmental and physiological factors was undertaken in 1971–72 (15 months) in the Niantic River estuary to elucidate some of the important aspects, of the growth and development of the seaweed Codium fragile. In general, Codium in the estuary has a growing season of from 6 to 9 months. Growth increments during this period are relatively constant. Temperature and salinity are the main limiting factors to growth, although low summer concentrations of inorganic nitrogen may also be involved. Reproduction by means of swarmers occurs only in late summer or autumn. Codium appears highly adapted to the role of a colonizing species. It not only possesses the capability to occupy the harshest of environments, but also a system of reproductive alternatives which facilitates rapid colonization. The availability of substrate for attachment is the chief factor limiting its spread in this estuarine system.

Stress tolerance of the invasive macroalgae Codium fragile and Gracilaria vermiculophylla in a soft-bottom turbid lagoon

“…G. vermculophylla had high performance at all sites, matching its wide distribution in Hog Island Bay ) and supporting the view of this species as being highly stress tolerant (Yokoya et al 1999;Wallentinus et al 2004;Rueness 2005). In contrast, C. fragile showed poor performance at near-mainland sites despite a reported tolerance to high nutrients, low salinity and low light (Malinowski and Ramus 1973;Hanisak 1979a;Trowbridge 1998), suggesting that invasions are unlikely in these locations. The native species often also had low performance at the near-mainland sites, indicating generally poor growth conditions.…”

“…80% of the total biomass (earlier identified as G. verrucosa, Thomsen 2004a, b;. C. fragile and G. vermiculophylla have both been described as successful invaders of shallow turbid lagoons and estuaries (Fralick and Mathieson 1973;Malinowski and Ramus 1973;Carlton and Scanlon 1985;Trowbridge 1998;Rueness 2005), a notion supported by their dominance in Hog Island Bay. We therefore expected the two aliens to have superior performance under conditions typical of such ecosystems, including low light availability due to high water column turbidity Lawson 2003), high mesograzer densities (e.g.…”

SEXUAL REPRODUCTIO IN CODIUM FRAGILE SSP. TOMENTOSOIDES (CHLOROPHYCEAE) FROM THE NORTHEAST COAST OF NORTH AMERICA1

“…Reproduction of Codium fragile involves fragmentation (Fralick and Mathieson 1972), drifting of entire plants (Moeller 1969) and production of motile reproductive cells (Malinowski and Ramus 1973). On the Pacific coast of North America (Borden andStein 1969), in Japan (Arasaki et al 1955) and in Australia (Williams 1925) C. fragile produces anisogametes with the zygote germinating into erect thalli.…”

Detecting the impacts of notorious invaders: experiments versus observations in the invasion of eelgrass meadows by the green seaweed Codium fragile

“…However, the prediction of such an extreme outcome does not consider factors that can limit the impacts of dense Codium beds. Codium has been suggested to be excluded by shading and increased sedimentation in dense eelgrass stands (Malinowski and Ramus 1973). Sparse seagrass beds may thus be more susceptible to invasion by macroalgae as they create physical conditions that facilitate macroalgal growth (Ceccherelli and Cinelli 1999) (c) Fig.…”

“…Although typically associated with hard substrates, including both rocky substrata and shells, this large seaweed is also able to epiphytically colonize exposed seagrass rhizomes (Garbary et al 2004), growing as long as or longer than the plants with which it is associated (authors, personal observations). Earlier studies suggested that Codium was a poor competitor for resources with native seagrass in soft-bottom habitats, due in part to the limited availability of hard substrata (Malinowski and Ramus 1973) and a greater vulnerability to environmental conditions in lagoonal systems relative to native algae (Thomsen and McGlathery 2007). However, Codium is tolerant to estuarine conditions (Kim and Garbary 2007), and its ability to grow directly on eelgrass rhizomes gives it the potential to develop dense populations in soft-bottom habitats.…”