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Introduction: In late June 2021, the Pacific Northwest region of the United States and Canada experienced an unprecedented atmospheric heatwave that co-occurred with one of the lowest day-time tide series of the year. Several consecutive days of air temperatures 10-20°C above normal, coupled with mid-afternoon low tides proved deadly for many rocky intertidal organisms, which live at the margin of land and sea. Methods: To assess short (weeks) and longer-term (1 year) impacts of the heatwave on rocky intertidal communities, we used long-term monitoring data collected annually at 16 sites throughout Washington State. Results and discussion: Our findings indicate that impacts were most severe at sites within the Salish Sea region of WA, where peak low tides occurred during the hottest, mid-afternoon hours. Focal species assemblages at Olympic coast sites, where low tides occurred in the morning, were largely spared. In addition, while the heatwave was associated with substantial short-term changes in acorn barnacle, rockweed, and California mussel assemblages, lasting impacts (1 year) were only observed in the mussel assemblage at the one Salish Sea site where this species is common. These findings will aid in forecasting both short-term and longer lasting impacts of future heatwave events and help direct potential mitigation efforts to regions and species assemblages where impacts will likely be greatest. [ABSTRACT FROM AUTHOR]

IntroductionIn late June 2021, the Pacific Northwest region of the United States and Canada experienced an unprecedented atmospheric heatwave that co-occurred with one of the lowest day-time tide series of the year. Several consecutive days of air temperatures 10-20°C above normal, coupled with mid-afternoon low tides proved deadly for many rocky intertidal organisms, which live at the margin of land and sea.MethodsTo assess short (weeks) and longer-term (1 year) impacts of the heatwave on rocky intertidal communities, we used long-term monitoring data collected annually at 16 sites throughout Washington State.Results and discussionOur findings indicate that impacts were most severe at sites within the Salish Sea region of WA, where peak low tides occurred during the hottest, mid-afternoon hours. Focal species assemblages at Olympic coast sites, where low tides occurred in the morning, were largely spared. In addition, while the heatwave was associated with substantial short-term changes in acorn barnacle, rockweed, and California mussel assemblages, lasting impacts (1 year) were only observed in the mussel assemblage at the one Salish Sea site where this species is common. These findings will aid in forecasting both short-term and longer lasting impacts of future heatwave events and help direct potential mitigation efforts to regions and species assemblages where impacts will likely be greatest.

Seaweeds are foundation species on rocky shores that are exposed to a series of stressors. These include wave exposure, desiccation, grazing, and human activities, with habitat fragmentation as a common result. As part of climate and biodiversity changes, we are expecting increased winds and more frequent storm events, warmer climate, and trophic downgrading of ecosystems, causing overgrazing events. Here, we present the results from a two-factorial mesocosm experiment on the relationship between wave exposure, habitat fragmentation and growth (branching and tip elongation) of Fucus vesiculosus in the intertidal and upper subtidal. We found that intertidal seaweeds branched significantly more at low than high wave exposure. There was no effect of habitat fragmentation on branching, and no effects on tip growth from either wave exposure or habitat fragmentation. The experiment suffered greatly from uncontrolled grazing. Gastropod coverage was higher inside seaweed patches than in the seaweed free areas between and outside of the patches. In basins with highly fragmented seaweed patches, we found more gastropods at low than high wave exposure, whereas in basins with low fragmentation we found more gastropods at higher wave exposure. The percent coverage of gastropods in the basins did not seem to impact seaweed growth. [ABSTRACT FROM AUTHOR]

Foundation species are essential to ecosystem function, but their role as habitat providers is predicated on their spatial dominance. Worldwide, kelps, seagrasses, corals, and other marine foundation species have declined. This is true also for rockweeds, the canopy-forming analog of subtidal kelp forests in temperate rocky intertidal ecosystems. On the west coast of North America, dense beds of the rockweed Silvetia compressa occur across large biogeographic regions, benefitting numerous species by ameliorating physical stress caused by sun exposure, desiccation, heat, and wave disturbance. Like many rockweed species, Silvetia is long-lived, slow-growing, and short-dispersing -- characteristics that reduce its resilience to disturbance. Using a generalized additive mixed-effects model with explicit spatial effects, we analyzed canopy cover data from 30 sites spanning 18 years, and we tested the hypothesis that Silvetia population trends are tightly linked to atmospheric climate conditions, particularly Santa Ana wind events (SAWs): strong, hot, and dry downslope winds that originate inland and move offshore. We found that the rockweed had declined markedly, particularly at sites south of the major biogeographic break, Point Conception (PC), including the California Channel Islands and southern California mainland, and a highly significant negative effect of dewpoint depression, a measure of moisture content in the atmosphere, on Silvetia cover across all three regions in this study. Our results suggest that any increases in the frequency or intensity of SAWs are likely to lead to large declines and possible extirpation of Silvetia, as well as the important ecological services the species provides. [ABSTRACT FROM AUTHOR]

Foundation species are essential to ecosystem function, but their role as habitat providers is predicated on their spatial dominance. Worldwide, kelps, seagrasses, corals, and other marine foundation species have declined. This is true also for rockweeds, the canopy-forming analog of subtidal kelp forests in temperate rocky intertidal ecosystems. On the west coast of North America, dense beds of the rockweed Silvetia compressa occur across large biogeographic regions, benefitting numerous species by ameliorating physical stress caused by sun exposure, desiccation, heat, and wave disturbance. Like many rockweed species, Silvetia is long-lived, slow-growing, and short-dispersing – characteristics that reduce its resilience to disturbance. Using a generalized additive mixed-effects model with explicit spatial effects, we analyzed canopy cover data from 30 sites spanning 18 years, and we tested the hypothesis that Silvetia population trends are tightly linked to atmospheric climate conditions, particularly Santa Ana wind events (SAWs): strong, hot, and dry downslope winds that originate inland and move offshore. We found that the rockweed had declined markedly, particularly at sites south of the major biogeographic break, Point Conception (PC), including the California Channel Islands and southern California mainland, and a highly significant negative effect of dewpoint depression, a measure of moisture content in the atmosphere, on Silvetia cover across all three regions in this study. Our results suggest that any increases in the frequency or intensity of SAWs are likely to lead to large declines and possible extirpation of Silvetia, as well as the important ecological services the species provides.

Intertidal seaweed beds form three-dimensional structures providing habitat for a variety of species. As such, ecosystem-based management of seaweed harvesting must take into consideration the impact of the harvest not only on the biomass but also on the morphology of the seaweed. We compare the morphology and vertical distribution of biomass and shoots in Ascophyllum nodosum from three sites with a 20 + year history of commercial harvesting with three corresponding control sites in southern New Brunswick, Canada. We found no significant impact of harvest history on the vertical distribution of shoots or biomass within individual clumps. At two of the three harvested sites, large clumps had a wider circumference than those at the control sites, suggesting that long-term harvesting increases the growth of shoots throughout the clumps; presumably caused by an increase in light penetration through the harvested canopy. We also compare biomass of littorinids, the most abundant invertebrates found in A. nodosum beds at low tide and found no significant difference between control and harvested sites. We conclude that the harvest of A. nodosum according to the current regulations in New Brunswick, does not have long-term impact on the morphology of the algae or on the abundance of its main inhabitant. [ABSTRACT FROM AUTHOR]

IntroductionChanges that occur during aging affect seed quality. Vigor is the first component of seed quality that decreases with aging seed, and followed by a decrease in germination capacity, seedling growth and establishment. The seeds of soybeans are classified in the orthodox seeds. These seeds contain high amount of lipid and protein. Seed viability can only be maintained until few months of storage under normal conditions. One of the important steps in soybean seed industry is maintaining seed quality during storage condition for the planting during next growth season or sales. Lack of a proper storage condition would affect the biochemical and physiological nature of soybean seeds and intensify their aging. Changes that occur during deterioration condition affect seed quality. Through the process of deterioration, seed vigor is the first traits of the seed quality that decreases, followed by a decrease in germination capacity, seedling growth and establishment. Wide range of deteriorative conditions (especially moisture content and temperature) may affect seed quality during storage which may lead to seed aging. Hence, to stimulate germination and increase the establishment of seedlings from ageing seeds, treatment can be done using different materials such as brown seaweed extract. To continue the experiment, normal seeds and aged seeds were sown in June 2018 and 2019 at a depth of 2 cm. Each plot consisted of 4 lines 6 m long with a distance of 50 cm between the lines and 10 cm width on the lines.Materials and MethodsA factorial experiment was performed based on a randomized complete block design with three replications at the research field of Shahroud University of Technology. In this study two sets of seeds including control seeds (un-aged) and aged seed were used and brown seaweed A. nodosum (0.3%) was applied for control, seed pretreatment, foliar spray and seed pretreatment+foliar spray. The brown seaweed extract was "Acadian™ Seaweed Powder" (produced in Canada) containing brown seaweed extract (Ascophyllum nodosum), and all the reagent and chemicals for experiments were purchased from Merck (Germany). Soybean seed Var. DPX. was collected from the Mazandaran agricultural research center. The water content of seeds was 12%. The seeds were those that harvested in the same year and kept in a controlled storage room at the temperature between 14 to 17 °C and relative humidity of 30 to 40% at the Agricultural Research and Training Center and Natural Resources of Mazandaran Province. For surface sterilization, soybean seeds were disinfected with 1% sodium hypochlorite for 60 seconds and then washed with distilled water. To prepare aged seeds in the laboratory, the seeds were incubated at 41°C and 95% relative humidity for 72 hours according to the method described previously. For each treatment, 100 g of the soybean seeds were soaked in 20 ml seaweed extract (0.3%) under ventilation condition for 6 hours, following by drying the seeds in the shade.Results and DiscussionIn this study, the results showed that the seed aging reduced the mean daily seedling field emergence, content of soluble sugar, leaf area index, stomatal conductance, oil yield and seed yield and also, increased the electrical conductivity and free amino acids content in the field condition. Whereas, the seed pretreatment with the seaweed extract in normal and aging conditions increased mean daily seedling field emergence 15.31% and 55.03% respectively. The values of leaf area index, stomatal conductance, oil yield and seed yield were increased with application of both pretreatment and foliar spray of seaweed extract, 34.51%, 23.72%, 91.68% and 87.85% respectively. Seed pre-treatment and foliar spraying with Ascophyllum nodosum brown seaweed extract at a concentration of 0.3% improved the deteriorated effects and significantly increased seed yield.ConclusionThis study concludes that the seaweed extract is effective to minimize negative effects of aging on seeds performance and has a great positive effect on the physiological and agronomic traits of soybean plant. Among the four methods used in this study, the seeds pretreatment+foliar spray was more effective.

Ascophyllum nodosum (L.) Le Jolis (Fucales, Fucaceae) is a modular intertidal brown alga that has the particularity of forming an air bladder once a year at the apical tip of the growing shoots. This characteristic provides a means for aging and estimating the growth of individuals. While it has long been recognized that growth can occur in older parts of the frond, this has not been properly assessed until now and has largely been overlooked when calculating the productivity of the species. Recent studies have suggested that the growth and elongation of older segments is minimal and thus has been used to infer past environmental conditions. Here we assessed the length and mass of successive internodal segments from 25 sites spread over both sides of the North Atlantic, covering a wide portion of the distribution of the species. By calculating the ratio of the mass and length of a segment divided by the segment produced the following year, we established that internodal segments continue accumulating mass for 1–5 years and increase in length for 1–3 years at most sites. Segments can almost triple their mass during their second year and more than double their length. These results indicate that previous productivity and growth estimates for A. nodosum based on apical growth alone greatly underestimate the true productivity of the species and its role in coastal carbon cycling. Furthermore, because they grow over several years, internodal segments should not be used to infer past environmental conditions or to reconstruct growth patterns over time. [ABSTRACT FROM AUTHOR]

Seeley et al., 2024 (Comment: A reexamination of Johnston et al., 2023, bed-scale impact and recovery of a commercially important intertidal seaweed. J. Exp. Mar. Biol. Ecol. 574) describe a number of reasons that they believe our study's experimental design was flawed and our inferential conclusions were incorrect. We believe that these claims are the result of misunderstandings of the objectives behind our sampling design and statistical analyses. Throughout this response to Seeley et al., we reiterate key objectives of our study design: examining rockweed harvest at a whole-bed scale, realistically capturing the effects of current commercial rockweed harvest methods in Maine, and using coastwide site averages to estimate effect sizes of rockweed harvest. The first claim by Seeley et al. that our study design severely undersampled rockweed beds ignores established sampling methodologies in rockweed research. The suggestion that our sampling design resulted in impact sites that were de facto control sites is not supported by our analyses that showed greater declines in mean rockweed height and biomass at impact sites relative to control sites. In response to their second claim that rockweed companies had control of key elements of our study design and execution, we detail our specific approaches to lessen any possibility for such conflicts to bias our findings. In the final section of our response, we present power analyses in support of our Before-After Control-Impact study design and we highlight the statistically significant effects of treatment on rockweed biomass that contradict Seeley et al.'s claim that we drew conclusions about biomass recovery based solely on large p -values. [ABSTRACT FROM AUTHOR]

• The seaweed extract (Ascophyllum nodosum) are used to reduce the negative effects of the seed aging. • Ellagic acid improve the effects of the seed aging in soybean. • The seed yield of soybean increased with the application of seaweed extract and ellagic acid. Loss of quality, viability and irreversible seed vigor over time due to seed aging is one of the main causes of reduction of quality and quantity of agricultural production. A wide range of secondary metabolites such as vitamins, growth regulators and antioxidant compounds were used to reduce the harmful effects of a variety of environmental stresses such as seed aging. These can be applied as seed pretreatment or foliar spraying of plants. To investigate the effect of seaweed extract (Ascophyllum nodosum) and ellagic acid on quality improvement of soybean, an experiment was designed and implemented in the field during 2019 and 2020. A factorial experiment was conducted based on a randomized complete block design (RCBD) with three replications. Two sets of seeds (un-aged and aged seeds), seed pretreatments and foliar spray treatments with ellagic acid and the seaweed extract to plants produced from aged seeds were conducted at three levels (control (zero), 50 mg/L of ellagic acid and 0.3% seaweed extract). The foliar spraying is done to improve the vigor of plants produced from aged seeds. Seed aging reduced the final emergence percentage under the field conditions. Seed pretreatments with the seaweed extract and ellagic acid increased the emergence. The amount of malondialdehyde, the activity of lipoxygenase, flavonoids and anthocyanins content also increased in the leaves of plants grown from the aged seeds in the field conditions. Seed aging reduced glutathione content, protein yield and seed yield. However, seed pretreatments with ellagic acid and the seaweed extract increased protein yield by 27.2% and 53.4%, respectively. Seed yield in plants grown from seeds treated with ellagic acid increased by 28.2%. Seed yield increased by 53.6% with application of seaweed extract as seed pretreatment. Foliar spray of ellagic acid and the seaweed extract to plants increased protein yield by 20.6% and 21.5%, respectively. Thus seed pretreatments and foliar spray of ellagic acid and the seaweed extract countered the effects of accelerated aging of soybean seed. [ABSTRACT FROM AUTHOR]

Fucus distichus, a rockweed common to the mid-intertidal shoreline within the San Francisco Estuary (previously known as F. gardneri), was injured during the Cosco Busan oil spill in November 2007 and subsequent clean-up actions. Restoration planning activities are underway to help recover F. distichus at sites within central San Francisco Bay where damage occurred. As a first step, we conducted shoreline surveys during the summers of 2012–2013 to map the occurrence of this rockweed. Of the 151.73 km of rocky shoreline within the central bay, F. distichus covered 32.16 km of shoreline. The alga generally occurred in narrow bands but formed expansive beds at locations with natural, flat bedrock benches. We also observed F. distichus on artificial substrata such as seawalls and riprap, but not on pilings. Samples of F. distichus from 11 sites throughout the central / east San Francisco Bay were genetically analyzed (microsatellite genotyping). The populations analyzed (1) had low genetic diversity, (2) the frequency of homozygotes was higher than expected (suggesting high inbreeding), and (3) also displayed geographic population structure, in part driven by very small differences in the midst of extremely low within-population genetic diversity. However, these genetic data do not raise concerns for restoration methods in terms of choosing donor populations and mixing F. distichus from different sites within the central bay. The choice of donor populations should be based on practical criteria for effective restoration; individuals will nonetheless be taken from locations as nearby to donor sites as possible. Various locations throughout the central San Francisco Bay are composed of cobble or small riprap that are populated with F. distichus, which could provide efficient means of translocating rockweed for future restoration activities.

With the increasing demand for seaweed resources worldwide, management must ensure that the harvest of wild seaweed stocks is sustainable. We evaluate the impact of over 25 years of commercial harvesting of Ascophyllum nodosum in eastern Canada by comparing the biomass and height of the seaweed in the late 1990s to the late 2010s over a broad spatial scale spanning the provinces of Nova Scotia and New Brunswick. There has been no significant decrease in the biomass of A. nodosum in either province, and biomass has increased in some regions of New Brunswick during that period. The average height of A. nodosum has decreased by 7.8 cm in Nova Scotia while it increased by 13.8 cm in New Brunswick. Biomass of A. nodosum in unharvested sectors was 7% higher than that in harvested sectors while height of A. nodosum in unharvested sectors in New Brunswick is similar to the values observed in harvested sectors. Over the same period, water temperature has increased in both provinces and, in recent years, has at times exceeded the optimal growing temperature for A. nodosum within bays in Nova Scotia. We conclude that the current management and harvest of A. nodosum in eastern Canada are sustainable and maintain the biomass and height of A. nodosum beds but that control sites are necessary to offer adequate comparisons as environmental conditions are changing. [ABSTRACT FROM AUTHOR]

Sentinel-2 satellite imagery has been successfully used to map submerged seagrasses in clear waters, and surface-canopy forming seaweed habitats in a range of water types. We examined the ability to use Sentinel-2 remote sensing reflectance to classify fully submerged seagrass and seaweed habitats in optically complex, temperate waters within a high priority management region in Atlantic Canada. To do so, we determined the “best” Sentinel-2 image available between 2015 and 2019 based on tidal height, absence of sun glint and clouds, and water transparency. Using the full Sentinel-2 tile, we atmospherically corrected the image using ACOLITE’s dark spectrum fitting method. Our classification goal was a two-class prediction of vegetation presence and absence. Using information obtained from drop-camera surveys, the image was first partially classified using simple band thresholds based on the normalized difference vegetation index (NDVI), red/green ratio and the blue band. A random forest model was built to classify the remaining areas to a maximum depth of 10 m, the maximum depth at which field surveys were performed. The resulting habitat map had an overall accuracy of 79% and ∼231 km2 of vegetated habitat were predicted to occur (total area 345.15 km2). As expected, the classification performed best in regions dominated by bright sandy bare substrate, and dense dark vegetated beds. The classification performed less well in regions dominated by dark bare muddy substrate, whose spectra were similar to vegetated habitat, in pixels where vegetation density was low and mixed with other substrates, and in regions impacted by freshwater input. The maximum depth that bottom habitat was detectable also varied across the image. Leveraging the full capacity of the freely available Sentinel-2 satellite series with its high spatial resolution and resampling frequency, provides a new opportunity to generate large scale vegetation habitat maps, and examine how vegetation extent changes over time in Atlantic Canada, providing essential data layers to inform monitoring and management of macrophyte dominated habitats and the resulting ecosystem functions and services.

Johnston et al., 2023 (Bed-scale impact and recovery of a commercially important intertidal seaweed. J. Exp. Mar. Biol. Ecol. 561) report that rockweed biomass recovers to pre-harvest levels one year after commercial harvest. The Johnston et al. study has two major problems in design, execution, and interpretation of results: 1) industry partner conflict of interest and statistically undetectable impact of the harvest treatment on Ascophyllum nodosum (rockweed) beds, 2) incomplete statistical analysis with inappropriate inferential conclusions about biomass recovery of harvested rockweed beds. Our analysis of their data shows that the only regions of the coast where rockweed biomass recovered to pre-harvest levels are the three regions where the harvest treatment was never detectable. In the one region where the harvest treatment was detectable, rockweed biomass did not recover to pre-harvest levels in a year. Rockweed is a foundational species in the rocky intertidal food web as well as an ecosystem engineer. The improper interpretation by Johnston, et al. of the study data is misleading ecosystem managers and the public about the impacts of commercial rockweed harvests. Most concerning, this paper sets a false foundation for marine policy on commercial rockweed harvesting in Maine. • My understanding is that highlights are only offered for full research ar8cles. • Our submission is not a full research ar8cle. [ABSTRACT FROM AUTHOR]

The importance of ecosystem-based management (EBM) frameworks for resource harvest has increased over the past several decades as ecosystems face numerous anthropogenic stressors. In these frameworks, resource managers must consider the suite of interactions that comprise food webs and how resource harvest drives responses in non-target organisms. In rocky intertidal zones along North Atlantic coastlines, rockweed (Ascophyllum nodosum)—a canopy-forming brown seaweed—has been commercially harvested for centuries, yet most research on the effects of harvest have focused on the responses of the target resource and the macroinvertebrate assemblage. In this study, we used a Before-After Control-Impact experiment to assess the bottom-up effects of commercial rockweed harvest on a high trophic-level consumer group (birds) in Maine (USA). Overall, there was no evidence for strong bottom-up forcing of rockweed harvest on birds' site visitation. There was a small (fewer than two birds) positive effect size of harvest during the one-year post-harvest recovery interval. Several of the trends observed for the full bird assemblage appear to be driven more strongly by the low tide than the high tide bird assemblage. Independent of treatment, site visitation by birds was low in our study (60% of surveys recorded no birds) and highlights questions about the use of rocky intertidal habitats relative to other habitat types in coastal birds' home ranges. To our knowledge, there are no comparable assemblage-level bird studies in this system that can provide context to our results. Further research on coastal birds' habitat use within home ranges and food-web connections with rockweed-associated macroinvertebrates is needed to more confidently incorporate this high trophic-level consumer group into an EBM framework for a rocky intertidal resource harvest. • Ecosystem-based management approaches are important in the rockweed (Ascophyllum nodosum) fishery, but knowledge gaps remain • There were both positive and negative effects of rockweed harvest on birds, but effect sizes were small • Low densities of birds during our surveys highlights the need to understand the relative contribution of rockweed habitats toward the total resource needs of coastal birds [ABSTRACT FROM AUTHOR]

As the value of ecosystem-based management (EBM) approaches is increasingly recognized in marine ecosystems, it is critical that the impacts of resource harvest are assessed at various spatial scales. This is particularly true for habitat-forming resources, such as wild seaweeds, that act as foundation species by physically structuring ecosystems. The impacts of spatially heterogeneous harvest may change with scale, and have different management implications based on the ecosystem process or organism under consideration. Ascophyllum nodosum (hereafter rockweed) is a canopy-forming fucoid seaweed endemic to rocky coastlines in the North Atlantic Ocean that has been harvested for centuries. We conducted a Before-After Control-Impact study of commercial rockweed harvest at 38 sites across the coast of Maine (USA) from 2018 to 2020 in an effort to understand impact and one-year recovery of two rockweed bed structural characteristics, height and biomass, at a scale similar to a single harvest event. Our results indicate that rockweed harvest is spatially heterogeneous at the scale of the rockweed bed, and as a result, the effect sizes of harvest at this scale are smaller than those reported in previous studies that assessed smaller spatial scales. Mean rockweed biomass recovered to pre-harvest values after one year of recovery, but mean rockweed height remained lower at impacted sites. While post-harvest recovery was generally high in our study, sites that experienced higher intensities of harvest were less likely to fully recover height or biomass one year post-harvest. Our findings provide resource managers with a bed-scale perspective that can inform EBM approaches, particularly for population-level management of harvested resources and impacts of harvest on highly mobile organisms—such as birds and fish—that interact with these ecosystems at larger spatial scales. • Rockweed harvest is spatially heterogeneous at the scale of the rockweed bed. • Effects of harvest on mean rockweed height and biomass are smaller at large scales. • Biomass, but not height, recovers one year after harvest. • Ecosystem-based management can benefit from considering various spatial scales. [ABSTRACT FROM AUTHOR]

Changes to associated communities when habitat is altered have been well documented in terrestrial and marine systems. In marine ecosystems, subtidal canopy removal of overlying vegetation is known to impact both physical and biological processes below. Recently, in Maine (USA), there has been much concern about the impact of harvesting (i.e., canopy removal) of Ascophyllum nodosum (rockweed) on the intertidal community. To examine the impacts of rockweed harvesting on the sediment structure and invertebrates associated with the sediment, control and experimentally harvested plots were established in May 2011 at Sears Island (Maine, USA). Monthly data collection through the summer and early fall included sediment cores, sieved infauna samples, and mobile megafauna quadrats. Sediment samples were analyzed for organic content as well as percent coarse sand, fine sand, silt, and clay. The experiment was repeated in 2012 in the same location with a modified design. In 2013 a commercially harvested site was sampled in the same manner before and after harvesting. Although differences in abundances of mobile megafauna were evident in the experimentally harvested sites, they were not evident in the commercially harvested site. Sediments and smaller invertebrates were mostly unaffected by canopy removal in both the experimentally and commercially harvested sites. While these data are contrary to those for subtidal canopy removal experiments, the rocky intertidal is a more physically dynamic habitat that may be tolerant of greater disturbance. [ABSTRACT FROM AUTHOR]

Commercial exploitation of Ascophyllum nodosum (rockweed) along the coast of Nova Scotia began in the late 1950s when it was used as a raw material for manufacturing alginate and 'kelp' meal. Today, this resource is used as a biostimulant extract for crops and animal feed supplements and is the main economic resource of the seaweed industry in the Maritime Provinces and Canada. The management of rockweed, by dividing the resource into many sectors, permitted the assessment of yield per unit area of bed. In Nova Scotia, mechanical harvesting of A. nodosum operated on a pulse of 2- to 3-year schedule providing yields of 21.9 to 47.7 wet t ha averaging 35.3 ± 7.6 wet t ha. Acadian Seaplants Limited (ASL) has become the dominant player in the region since 1995 with more than 75% of the total biomass under its leases and more than 90% of the total landing of rockweed in the last 13 years. Sustained harvests at ASL leases and under an annual harvest schedule using hand cutting methods have averaged 17.4 ± 2.6 t ha. Exploitation rates above 35% of the harvestable crop lead to a pulse harvest strategy and the need to move infrastructure year after year. In New Brunswick, a new approach to management began in 1995 with a regulated 17% exploitation rate. Thus, the yield in that province is 14.3 wet t ha. The current summer standing crop for this region has been calculated at 352,723 wet t, covering an area of 4,960 ha, with an average biomass of 71.3 t ha. The harvest in the region reached peak landings in 2010 with just over 40,100 t. The consistent yield per hectare of A. nodosum beds is proof of good management practices and an ecologically sustainable harvest in the Canadian Maritimes. [ABSTRACT FROM AUTHOR]

Burgeoning global demand for products derived from seaweeds is driving the increased removal of wild coastal seaweed biomass, an emerging low trophic level industry. These products are marketed as organic and 'sustainable.' Brown macroalgae, such as kelps (Laminariales) and rockweeds (Fucales), are foundational species that form underwater forests and thus support a diverse vertebrate, invertebrate, and algal community-including important commercial species-and deliver organic matter to coastal ecosystems. The measure of sustainability used by the rockweed ( Ascophyllum nodosum (L.) LeJolis) industry, maximum sustainable yield, accounts for neither rockweed's role as habitat for 150+ species, including species of commercial or conservation significance, nor its role in coastal and estuarine ecosystems. To determine whether rockweed cutting is 'sustainable' will require data on the long-term and ecosystem-wide impacts of cutting rockweed. Once a sustainable level of cutting is determined, strict regulation by resource managers will be required to protect rockweed habitat. Until sustainable levels of cutting and appropriate regulations are identified, commercial-scale rockweed cutting presents a risk to coastal ecosystems and the human communities that depend on those ecosystems. [ABSTRACT FROM AUTHOR]