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This study investigated the effects of 67 species of macroalgae on methanogenesis and rumen fermentation in vitro. Specimens were analyzed for their effect on ruminal fermentation and microbial community profiles. Incubations were carried out in an automated gas production system for 24-h and macroalgae were tested at 2% (feed dry matter basis) inclusion rate. Methane yield was decreased 99% by Asparagopsis taxiformis (AT) when compared with the control. Colpomenia peregrina also decreased methane yield 14% compared with control; no other species influenced methane yield. Total gas production was decreased 14 and 10% by AT and Sargassum horneri compared with control, respectively. Total volatile fatty acid (VFA) concentration was decreased between 5 and 8% by 3 macroalgae, whereas AT reduced it by 10%. Molar proportion of acetate was decreased 9% by AT, along with an increase in propionate by 14%. Asparagopsis taxiformis also increased butyrate and valerate molar proportions by 7 and 24%, respectively, whereas 3 macroalgae species decreased molar proportion of butyrate 3 to 5%. Vertebrata lanosa increased ammonia concentration, whereas 3 other species decreased it. Inclusion of AT decreased relative abundance of Prevotella, Bacteroidales, Firmicutes and Methanobacteriaceae, whereas Clostridium, Anaerovibrio and Methanobrevibacter were increased. Specific gene activities for Methanosphaera stadtmane and Methanobrevibacter ruminantium were decreased by AT inclusion. In this in vitro study, Asparagopsis taxiformis was most effective in decreasing methane concentration and yield, but also decreased total gas production and VFA concentration which indicates overall inhibition of ruminal fermentation. No other macroalgae were identified as potential mitigants of enteric methane. [ABSTRACT FROM AUTHOR]

In our previous research, the supplementation of Ulva sp. seaweed meal in shrimp feeds as a replacement for fish meal (FM) resulted in growth depression. To understand the factors causing the growth reduction and explore the effects of the seaweed meal as a substitution for soybean meal (SBM), a series of growth trials were conducted in the present study. Shrimp (initial mean weight 0.24, 0.15, and 0.98 g in trials 1-3, respectively) were stocked at 10 shrimp per tank (n = 4) and offered diets for 5 to 6 weeks. In trial 1, FM level was fixed and SBM was replaced using incremental level of the second batch Ulva meal (UM2). Two additional diets were formulated to allow comparison of high inclusion levels of seaweed meal from three batches (UM1-3). Results confirmed reductions in performance as replacement of SBM by Ulva meal was increased. This data also demonstrated significant difference between batches of the Ulva meal with the UM2 producing the poorest results. To elucidate if digestible protein was limiting growth, in trial 2 feeds were formulated on an equal digestible protein basis. At the end of trial 2, shrimp fed with diets containing UM2 exhibited significantly reduced growth performance, survival, and lipid content of whole shrimp body as well as increased feed conversion ratio (FCR) compared to the reference diet. Although performance of shrimp was depressed in the treatments containing UM1 and UM3, this was less than that of trial 2, indicating that protein quality may be part of the problem. Given the level of protein replacement, other components of Ulva meal are likely to be causing poor performance. A third trial was performed to evaluate the potential of the fourth batch Ulva meal (UM4) containing relatively higher protein content than the first three batches. In this trial, the growth, survival, and lipid content of whole shrimp body also decreased as the level of UM4 was increased. To survey possible problems caused by high levels of minerals, the meals and select diets were analyzed for mineral content. Clearly there are shifts in mineral profiles; however, there is no obvious correlation to a mineral. Other possible reasons would include anti-nutrients present in the algae. If Ulva meals are to be used to their full potential, e.g., as a primary protein source, the anti-nutritional components will need to be identified, specific lines of plants with enhanced nutrient value need to be developed and of course processing technologies evaluated to produce a high quality commercial product. [ABSTRACT FROM AUTHOR]

A growth trial and a digestibility trial were conducted to evaluate seaweed Ulva sp. as a substitution for fish meal (FM) in commercial-type feed formulation for Pacific white shrimp, Litopenaeus vannamei. Towards this goal, the 6-week growth trial utilized increasing levels (0, 6.35, 12.7, 19.05, and 25.4%) of the first batch of Ulva meal (UM1) to replace up to 8% FM in a plant-based feed formulation. At the end of the growth trial, shrimp offered diets containing 12.7, 19.05, and 25.4% UM1 exhibited significantly reduced weight gain. Apparent net protein retention (ANPR) was significantly decreased, while feed conversion ratio (FCR) was significantly increased when shrimps were fed with diets containing 19.05 and 25.4% UM1. Crude lipid content of whole shrimp samples were significantly decreased when UM1 was supplemented in the diets. Apparent digestibility coefficients of dry matter, energy, protein, and amino acids of two batches of Ulva meal (UM1 and UM2) were determined using chromic oxide as an inert maker and the 70:30 replacement technique. Energy and protein digestibility of UM1 and UM2 were significantly lower than FM and soybean meal (SBM) which were run at the same time. As a result of relatively low protein availability, individual amino acids digestibility of UM1 and UM2 are also significantly lower than those of FM and SBM. Results of the present study indicate that UM1 can be included in the shrimp diet up to 6.35% to replace 2% fish meal without resulting in growth depression. The low nutrients availability and high mineral contents of Ulva meal may explain a portion of the observed reduction in shrimp growth. [ABSTRACT FROM AUTHOR]

The genus Porphyra is ancient, successful, and morphologically simple. Its members provide a particular challenge to systematists who must decide whether shared features are a result of homoplasy, or reflect recent common ancestry. Three species of diminutive Porphyra with widespread geographic origins share many common morphological features: P suborbiculata Kjellm. has been reported from the west Pacific and Indian Oceans, P. carolinensis Coll et J. Cox from the west Atlantic, and P lilliputiana W. A. Nelson, G. A.Knight et M. W. Hawkes from New Zealand. Comparison of 18S rDNA sequence data from small Porphyra thalli from Mexico, Japan, New Zealand, Australia and Connecticut indicate that these three taxa in fact belong to one cosmopolitan species, which is distributed over three oceans and two hemispheres. Analysis of sequence data from introns present in the 18S rDNA and from the ITS region suggest that this distribution may be linked to human activity, and raises the question of to which geographic locality this entity is truly endemic? [ABSTRACT FROM AUTHOR]

The identification of two Atlantic kelp species, Laminaria longicruris and L. saccharina, has been controversial. In order to know if these two species are conspecific, plastid-encoded RuBisCo spacer and nuclear rDNA ITS sequences were analyzed from twelve individuals of L. longicruris, five of L. saccharina, from Connecticut and Nova Scotia. Four individuals of L. digitata from the above coasts were also analyzed as reference in this study. All RuBisCo spacer sequences from L. longicruris and L. saccharina were exactly identical except for one individual with three different nucleotides. Zero to five different nucleotides of ITS sequences, inculding four polymorphic sites, were found in two species. However, their RuBisCo spacer and ITS sequences are quite different from those of L. digitata. These results strongly suggest that L. saccharina (L.) Lamour. 1813 is conspecific with L. longicruris De La Pylaie 1824 and the different local populations, despite various morphotypes, may be genetically very similar. [ABSTRACT FROM AUTHOR]

Given their rapid growth and nutrient assimilation rates, Porphyra spp. are good candidates for bioremediation. The production potential of two northeast U.S. Porphyra species currently in culture ( P. purpurea and P. umbilicalis) was evaluated by measuring rates of photosynthesis (as O2 evolution) of samples grown at 20° C. Gametophytes of P. umbilicalis photosynthesized at rates that were 80% higher than those of P. purpurea over 5–20° C at both sub-saturating and saturating irradiances (37 and 289 μmol photons m−2 s−1). Porphyra umbilicalis was both more efficient at low irradiances (higher alpha) and had a higher Pmax than did P. purpurea (23.0 vs. 15.6 μmol O2 g−1 DW min−1), suggesting that P. umbilicalis is a better choice for mass culture where self-shading may be severe. The photosynthesis-irradiance relationship for the Conchocelis stage of P. purpurea was also examined. Tufts of filaments, grown at 10, 15, and 20° C, were assayed at growth temperatures at irradiances ranging from 0–315 μmol photons m−2 s−1. Tufts were slightly more productive at 15° than at 10° C, but only ca. 4–6% as productive as gametophytes. Maximum rates of net photosynthesis were reduced by 66–74% in tufts grown at 20° C (only about 2% of gametophytes). The Conchocelis stage, however, need not limit mariculture operations; once Conchocelis cultures are established, they can be maintained over the long-term as ready sources of spores for net seeding. [ABSTRACT FROM AUTHOR]

Porphyra perforata is a common species off the Pacific coast of Baja California peninsula. In situ growth, phenology and reproductive characteristic of this plant are being determined in order to evaluate the feasibility of its culture in open water conditions. Contrary to previous studies that describe this species as ephymeral, P. perforata is present all year around off the north coast of the Baja California peninsula. Its vertical distribution is limited to a band, +50 to +150 cm above sea level. However, subtidal growth transplant experiments showed that the plants are capable of growing down to a depth of 5 m. Highest growth rates were observed from February to July, then tissue was lost as a consequence of sexual reproduction. Biomass continues to decreases for the rest of the year. About 50% of the plants were reproductive by May and more than 90% by August. Oysters shells were introduced and collected every month to evaluate the presence of chonchocelis phase and P. perforata recruitment. Chonchocelis was observed all year and new recruits were present from September to February. These results suggest that the foliar phase P. perforata could be cultured in the ocean for about six months of the year and could be culture subtidally. [ABSTRACT FROM AUTHOR]

As one part of a multi-institutional project on the biology of Porphyra, we collected extensive population samples of native Porphyra species from Long Island Sound to Nova Scotia. Samples were initially identified to species based on morphological features using taxonomic keys in Bird & McLaughlin (1992). Collections were analyzed using starch gel electrophoresis to look for intra-specific variation useful in assessing population genetics. Isozyme variation in samples that had been originally identified as Porphyra leucosticta was far greater than expected. Samples from some collections differed by as much as 7 out of 7 loci. Other investigators have used starch gel electrophoresis to reveal cryptic differences in Porphyra that led to the descriptions of new species. In light of our isozyme results, we began a thorough examination of what had been identified as P. leucosticta in the northwestern Atlantic. The study included new collections as well as herbarium specimens. We examined morphology, habitat, seasonality, reproductive patterns, cell size & shape. We also extracted DNA and sequenced 1484bp of the rbcL gene. Based on this evidence, we feel we can circumscribe at least five distinct taxa of Porphyra not previously described from the northwestern Atlantic. Whether these represent new species, or previously described taxa from other geographic regions, we are not yet certain. We present here in detail, descriptions of each species along with summarized results of isozyme and DNA analyses. [ABSTRACT FROM AUTHOR]