Cultivation of Macrocystis integrifolia (Laminariales,Phaeophyta) in southeastern Alaskan waters

The artificial culture of Macrocystis integrifolia in southeastern Alaskan waters has been initiated as a first step in a project to augment the existing herring roe-on-kelp fishery in the state. The growing of Macrocystis in Prince William Sound has the potential of considerably enhancing this fishery by eliminating the costly importation of this kelp from southeast Alaska. In an ongoing feasibility study, Macrocystis has been cultured under laboratory conditions through the embryonic sporophyte stage and outplanted in waters near Sitka, Alaska (57° N). Growth of the outplanted kelps has been monitored as a function of the time and depth of the outplanting. Preliminary results suggest that light is limiting for growth in winter and that the optimal depth for outplanting will vary with the season.     

Effects of plant growth substances on the conchocelis phase of Alaskan Porphyra (Bangiales,Rhodophyta) species in conjunction with environmental variables1

The effect of plant growth substances (PGSs) on conchocelis growth of Alaskan Porphyra (P. abbottiae V. Krishnam., P. pseudolanceolata V. Krishnam., P. pseudolinearis Ueda) was investigated. Growth was measured under different combinations of PGS concentrations (0, 0.1, 0.2, 0.4, 0.8, 1.6, and 3.2 ppm), PGS type (gibberellic acid, kinetin, and indole‐3‐acetic acid), temperature (7, 11, and 15°C), and photoperiod (16:8 light:dark [L:D] cycle and 8:16 L:D cycle). Plant growth substances effectively promoted the growth of Porphyra conchocelis. Depending on culture conditions, growth rates were increased relative to controls 6.9%–31.7% for P. abbottiae, 4.7%–25.7% for P. pseudolanceolata, and 8.9%–35.1% for P. pseudolinearis. Maximal growth of P. abbottiae occurred with 0.8 ppm kinetin, 15°C, and short‐day conditions (8:16 L:D). Porphyra pseudolanceolata exhibited maximal growth with 0.4 ppm indole‐3‐acetic acid, 7°C, and long days (16:8 L:D). Indole‐3‐acetic acid also effected maximal growth of P. pseudolinearis at 0.4 ppm, 15°C, and long‐day conditions (16:8 L:D). For P. abbottiae and P. pseudolinearis, intermediate PGS concentrations (0.4–1.6 ppm) had the greatest growth‐stimulating effects, whereas for P. pseudolanceolata, higher growth generally occurred at lower concentrations (0.1–0.8 ppm). Kinetin and indole‐3‐acetic acid had more influence on the conchocelis phase than gibberellic acid. The PGS concentrations greater than 1.6 ppm had a diminishing effect on growth, especially in P. pseudolanceolata. For P. abbottiae and P. pseudolinearis, higher temperatures resulted in higher growth rates, in contrast to P. pseudolanceolata, which grew faster at the lower temperatures.     

Commercial potential of seaweeds from St Lawrence Island,Alaska

This study assessed the possibility of using drift and subtidal seaweeds from St Lawrence Island, Alaska (lat. 63°N) for sale by the native population after simple processing. Over 125 km of coastline were surveyed for distribution of both drift and subtidal seaweeds. Drift seaweed wet weight densities ranged from 0.2 to over 9 kg m⁻², with an average of over 4 t km⁻¹ in the areas sampled. Attached, benthic seaweed densities ranged from 0.15 to 0.32 kg m⁻². Thirty and 35% of the biomass was composed of Agarum cribrosum and species of Laminaria, respectively, both as drift and as benthic seaweed. Data from tagged Laminaria indicated that growth rates were relatively slow for most of the year. The drift seaweed resource on the coasts south and west of the city of Gambell appeared to have good potential for a small-scale commercial harvest. (*author for correspondence)     

PHYCOBILIN CONTENT OF THE CONCHOCELIS PHASE OF ALASKAN PORPHYRA (BANGIALES,RHODOPHYTA) SPECIES: RESPONSES TO ENVIRONMENTAL VARIABLES1

Variations of pigment content in the microscopic conchocelis stage of four Alaskan Porphyra species were investigated in response to environmental variables. Conchocelis filaments were cultured under varying conditions of irradiance and nutrient concentrations for up to 60 d at 11°C and 30 psu salinity. Results indicate that conchocelis filaments contain relatively high concentrations of phycobilins under optimal culture conditions. Phycobilin pigment production was significantly affected by irradiance, nutrient concentration, and culture duration. For Porphyra abbottiae V. Krishnam., Porphyra sp., and Porphyra torta V. Krishnam., maximal phycoerythrin (63.2–95.1 mg · g dwt^?1) and phycocyanin (28.8–64.8 mg · g dwt^?1) content generally occurred at 10 μmol photons · m^?2 · s^?1, f/4–f/2 nutrient concentration after 10–20 d of culture. Whereas for Porphyra hiberna S. C. Lindstrom et K. M. Cole, the highest phycoerythrin (73.3 mg · g dwt^?1) and phycocyanin (70.2 mg · g dwt^?1) content occurred at 10 μmol photons · m^?2 · s^?1, f nutrient concentration after 60 d in culture. Under similar conditions, the different species showed significant differences in pigment content. P. abbottiae had higher phycoerythrin content than the other three species, and P. hiberna had the highest phycocyanin content. P. torta had the lowest phycobilin content.     

Growth and pigmentation of juvenile Porphyra torta (Rhodophyta) gametophytes in response to nitrate, salinity and inorganic carbon

The leafy gametophytic phase of Porphyra torta Krishnamurthy(Rhodophyta), a candidate species for mariculture in Alaska, grows only inwinter and early spring and is restricted to the outer coast of southeastAlaska. To help determine specific environmental factors limiting theseasonal and geographic distribution of this species, culture experimentswere conducted using environmentally realistic levels of three physicalfactors. Growth and phycoerythrin concentration in juvenile gametophyteswere compared under combinations of nitrate, salinity, and inorganiccarbon representing the maximum and minimum levels of each factor in themarine environment. Recovery experiments were also conducted todetermine whether blades affected by low nutrient or salinity levels couldregain normal growth rates and pigment levels. To make statistically validcomparisons of growth rates among treatment groups, where repeatedmeasures were used, a two-stage analysis was tested and found to beappropriate. Low nitrate had a significant, negative effect on growth andphycoerythrin concentration. Salinity had a weak, negative effect on bladegrowth, while inorganic carbon had no observed effect on blade growth,and neither had a significant effect on phycoerythrin concentration. Bladesaffected by low nitrate were able to regain normal growth rates and higherthan normal pigment levels when nitrate was increased, after up to 6 weeksof exposure. The growth rate, modeled from the data, increased with timeinitially, dependent on nitrate level.     

Recolonization and restoration of upper intertidal Fucus gardneri (Fucales,Phaeophyta) following the Exxon Valdez oil spill

The Exxon Valdez oil spill in March 1989 and subsequent cleanup caused injury to intertidal Fucus gardneri populations especially in the upper intertidal. A survey in 1994 in Prince William Sound, Alaska showed that the upper boundary of Fucus populations at oiled sites was still an average of 0.4 m lower than the upper boundary at unoiled sites.Restoration of severely damaged Fucus populations was started on a small-scale at a heavily oiled rocky site in Herring Bay, Prince William Sound. Experiments employed mats of biodegradable erosion control fabric to act as a substratum for Fucus germlings and to protect germlings from heat and desiccation stress. A series of plots was covered with mats made from a resilient coconut-fiber fabric in June 1993. Half of the mats were inoculated with Fucus zygotes. A series of uncovered control plots was also monitored. There was no enhancement of Fucus recruitment on the rock surfaces under the mats. Dense populations of Fucus developed on the surface of all of the mats by the summer of 1994. The natural rock surfaces in the control plots, both inoculated and not, were barren of macroscopic algal cover. By September 1994, the juvenile thalli on the mats were approximately 2 cm in length. Inoculating the mats had an effect only in the upper region of the intertidal. It is expected that the thalli will become fertile during the 1995 season. These thalli may serve as a source of embryos to enhance the recovery of new Fucus populations in this high intertidal area.     

PHOTOSYNTHESIS AND RESPIRATION OF THE CONCHOCELIS STAGE OF ALASKAN PORPHYRA (BANGIALES,RHODOPHYTA) SPECIES IN RESPONSE TO ENVIRONMENTAL VARIABLES1

Photosynthesis and respiration of three Alaskan Porphyra species, P. abbottiae V. Krishnam., P. pseudolinearis Ueda species complex (identified as P. “pseudolinearis” below), and P. torta V. Krishnam., were investigated under a range of environmental parameters. Photosynthesis versus irradiance (P–I) curves revealed that maximal photosynthesis (P_max), irradiance at maximal photosynthesis (I_max), and compensation irradiance (I_c) varied with salinity, temperature, and species. The P_max of Porphyra abbottiae conchocelis varied between 83 and 240 μmol O₂ · g dwt^?1 · h^?1 (where dwt indicates dry weight) at 30–140 μmol photons · m^?2 · s^?1 (I_max) depending on temperature. Higher irradiances resulted in photoinhibition. Maximal photosynthesis of the conchocelis of P. abbottiae occurred at 11°C, 60 μmol photons · m^?2·s^?1, and 30 psu (practical salinity units). The conchocelis of P. “pseudolinearis” and P. torta had similar P_max values but higher I_max values than those of P. abbottiae. The P_max of P. “pseudolinearis” conchocelis was 200–240 μmol O₂ · g dwt^?1 · h^?1 and for P. torta was 90–240 μmol O₂ · g dwt^?1 · h^?1. Maximal photosynthesis for P. “pseudolinearis” occurred at 7°C and 250 μmol photons · m^?2 · s^?1 at 30 psu, but P_max did not change much with temperature. Maximal photosynthesis for P. torta occurred at 15°C, 200 μmol photons · m^?2 · s^?1, and 30 psu. Photosynthesis rates for all species declined at salinities <25 or >35 psu. Estimated compensation irradiances (I_c) were relatively low (3–5 μmol · photons · m^?2 · s^?1) for intertidal macrophytes. Porphyra conchocelis had lower respiration rates at 7°C than at 11°C or 15°C. All three species exhibited minimal respiration rates at salinities between 25 and 35 psu.     

155 Mapping Floating Kelp Beds in Alaska With Remote Sensing

The commercial harvest of floating kelps has promise as a business opportunity that could be especially valuable for small communities in southeast Alaska. The giant kelp, Macrocystis, is harvested mainly for the commercial herring roe‐on‐kelp harvest in Alaska. In addition, in southeast Alaska the two other species of floating kelps, Nereocystis luetkeana and Alaria fistulosa, have been commercially harvested since 1992 for use as agrochemicals by the Alaska KelpCo. The continued existence of this company and others that may wish to harvest seaweeds on a commercial basis is threatened by the lack of a kelp harvest management system in Alaska. The objective of this research is to develop a reliable and cost effective method for estimating the aerial extent and the standing crop biomass of the floating kelps in SE Alaska. We are employing an aerial multispectral imaging system that can be flown at varying altitudes to achieve spatial resolutions ranging from 0.5 to 2 meters. We are investigating whether the three species have unique spectral or textural characteristics in the multispectral imagery that can be used to differentiate the populations. The end products for this project will be kelp resource maps that delineate the spatial extent and biomass of kelp populations within the beds and a methodology for assessing kelp beds with mixed species composition. These products will find use by resource managers such as the Alaska Department of Fish and Game and the Department of Natural Resources.     

Purification and Properties of an Elicitor of Castor Bean Phytoalexin from Culture Filtrates of the Fungus Rhizopus stolonifer

Evidence has been obtained for the presence in filtrates of 3-day-old cultures of the fungus Rhizopus stolonifer grown on potato-dextrose medium of both high molecular weight and low molecular weight elicitors of the production of the phytoalexin casbene in cell-free extracts of castor bean (Ricinus communis L.) seedlings. The high molecular weight elicitor activity was purified by means of gel filtration chromatography. Both protein and carbohydrate are associated with the most purified fraction containing elicitor activity. The elicitor is inactivated by treatments at 60 C or higher temperatures for 15 minutes. The molecular weight of the purified elicitor was estimated from gel filtration chromatography in 10 mm Na-phosphate (pH 7) to be 30,000 ± 5,000. Treatments of the purified elicitor fraction with either sodium periodate or the nonspecific protease preparation, pronase, substantially reduced its activity as an elicitor of casbene production. On the basis of these properties it is concluded that the elicitor is most likely a protein and may be a glycoprotein. It is estimated that 2 × 10⁻⁸ m elicitor gives about a 14-fold increase in casbene synthetase activity in extracts of treated split seedlings in comparison with controls. This corresponds to about 50% of the maximal activity obtainable in this assay system developed to measure elicitor activity.