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Gracilaria vermiculophylla (Ohmi) Papenfuss is an invasive alga that is native to Southeast Asia and has invaded many estuaries in North America and Europe. It is difficult to differentiate G. vermiculophylla from native forms using morphology and therefore molecular techniques are needed. In this study, we used three molecular markers ( rbcL, cox2- cox3 spacer, cox1) to identify G. vermiculophylla at several locations in the western Atlantic. RbcL and cox2- cox3 spacer markers confirmed the presence of G. vermiculophylla on the east coast of the USA from Massachusetts to South Carolina. We used a 507 base pair region of cox1 mt DNA to (i) verify the widespread distribution of G. vermiculophylla in the Virginia ( VA) coastal bays and (ii) determine the intraspecific diversity of these algae. Cox1 haplotype richness in the VA coastal bays was much higher than that previously found in other invaded locations, as well as some native locations. This difference is likely attributed to the more intensive sampling design used in this study, which was able to detect richness created by multiple, diverse introductions. On the basis of our results, we recommend that future studies take differences in sampling design into account when comparing haplotype richness and diversity between native and non-native studies in the literature. [ABSTRACT FROM AUTHOR]

Changes in the size of intracellular nitrogen pools and the potential feedback by these pools on etaximum N uptake (NH[SUB4] and NO[SUB3]) rates were determined for Chaetomorpha linum (Müller) Kützing grown sequentially under nutrient-saturating and nutrient-limiting conditions. The size of individual pools in N-sufficient could be ranked as residual organic N (RON) comprised mainly of amino acids and compounds > protein N > NO[SUB3] > NH[SUB4] chlorophyll N. When the external N supply was removed, growth rates remained high and individual N pools were depleted at exponential rates that reflected both dilution of existing pools by the addition of new biomass from growth and movement between the pools. Calculated fluxes between the tissue N pools showed that the protein pool increased throughout the N depletin period and thus did not serve a storage function. RON was the largest storage reserve; nitrate was the second largest, but more temporary, storage pool that was depleted within to days. Upon N resupply, the RON pool increased 3 × faster that either the inogrance or protein pools, suggesting that prtein synthesis was the rate-limiting step in N assimilation and caused a buildup of intermediate storage compuinds. Maximum uptake rates for both NH[SUB4] And NO[SUB3,SUP-] varied inversely with macroalagal N status and appeared to be controlled by changes in small intracellular N pools. Uptake of NO[SUB3,SUP-] showed an initial lag phase, but the initial uptake of NH[SUB4,SUP+] Pool was depleted in the absence of an external N supply. A strong negative correlation between the RON pool the and maximum assimilation uptake rates for both NH[SUB4,SUP+] And NO[SUB3,SUP-] suggested a feedback control or assimilatin uptake to the buildup and depletin of organic compounds. Enhanced uptake and the accumulatin of N as simple organic compounds or nitrate both provide a temporary mechanism to buffer against the asynchrony of N supply and demans in C. linum. [ABSTRACT FROM AUTHOR]