Estimates of numbers of kelp gulls and Kerguelen and Antarctic terns breeding at the Prince Edward Islands, 1996/1997–2008/2009

Breeding numbers of Laridae and other surface-nesting seabirds have been monitored at sub-Antarctic Marion Island since 1996/1997 and counts of breeding birds were made at nearby Prince Edward Island in December 2001 and December 2008. Four species are regular breeders at the islands: Subantarctic skua Catharacta antarctica, kelp gull Larus dominicanus, Antarctic tern Sterna vittata and Kerguelen tern S. virgata. The latter three species currently each have populations of below 150 breeding pairs at the islands. Kelp gull numbers appear to be relatively stable though they may have decreased since the 1980s. Kerguelen tern numbers decreased and then recovered at Marion Island, but numbers of the species have declined at Prince Edward Island and it maintains a tenuous foothold there. The small Antarctic tern population appears to be stable.     

Colonisation of South African kelp-bed canopies by the alien mussel Mytilus galloprovincialis: extent and implications of a novel bioinvasion

The Mediterranean mussel Mytilus galloprovincialis is the most significant invasive alien marine species in South Africa and, although not normally found subtidally, has recently been observed colonising heads and stipes of the kelp species Ecklonia maxima in False Bay. We quantified this invasion and explored its ecological implications. Transects laid across kelp beds revealed that 10.34% of kelp individuals surveyed bore canopy mussels, with kelp heads (10.07%) being far more commonly infected than stipes (0.27%). Twenty kelp individuals with infected heads and 20 with infected stipes were separately collected for more-detailed examination. Wet mass of mussels on these kelp heads ranged from 2.5 to 2 462 g (median 86.4 g, interquartile range 14.8–353.8 g) and that of mussels on the stipes from 7.6 to 3 492 g (median 595.5 g, interquartile range 194.0–955.0 g). Mussel clumps consisted mostly of individuals <40 mm in length. Mussel clumps supported a rich biota of 80 invertebrate and 13 algal species. Larger clumps supported more epibiotic species, and those on stipes more species than those of comparable mass on kelp heads. The mussels and their associated epibiotic species negatively affected kelp buoyancy, but rarely enough to overcome natural buoyancy. Some kelp individuals that had been toppled by the weight of mussels and their epibiotic species, however, were encountered in situ. Implications of this invasion include large increases in animal biomass and species richness in the kelp canopy, plus reductions in kelp buoyancy and increased hydrodynamic drag on infected kelps, increasing their probability of being uprooted. Uprooted kelp individuals can raft long distances, potentially transporting both native and alien species to distant sites.     

Kelp forests in False Bay: urchins vs macroalgae in South Africa’s southwest coast biogeographical transition zone

Kelp forests along South Africa's southwest coast occur in a region of biogeographical overlap. Commonly referred to as transition-zone kelp forests, these dynamic ecosystems are particularly susceptible to grazing from species such as urchins. This study explores relationships between urchins and macroalgae in transition-zone kelp forests along the western side of False Bay. Six kelp forests in this region were sampled. At each site, the urchin Parechinus angulosus and kelp Ecklonia maxima were counted, percentage cover of understorey algae was recorded, and drift algae were collected. Despite variability in urchin and algal cover across sites, kelps generally increased from north to south, while urchins did the opposite. Urchins were negatively associated with macroalgae, although this relationship was weak. A localised threshold of 50 urchins m^–2 was identified, above which kelp density failed to increase above 10 m^–2 and percentage cover of understorey algae usually remained below 20%. Surprisingly, no relationship was discovered between drift algae and attached algae. The findings highlight the complexity of these cool-water environments. To better understand the role of urchins in this system, particularly under changing climate trends, experimental research into the feeding behaviour and possible effects of urchins on attached algae in the presence/absence of drift algae is advised.     

Comparison of assemblages and some life-history traits of seabirds in the Humboldt and Benguela systems

There are 21 and 15 species of seabirds that breed in the Humboldt and Benguela upwelling systems respectively. Only two species of gull are common to both systems, one as an endemic subspecies to the Benguela system. Eleven species and two subspecies are endemic (or nearly so) to the Humboldt system; seven species and one subspecies to the Benguela system. Each system has an endemic penguin, sulid, cormorant and tern that feed mainly on anchovy Engraulis spp., sardine Sardinops sagax or both these fish. The Peruvian pelican Pelecanus thagus also feeds primarily on these prey items. A plentiful availability of food has resulted in many of these seabirds attaining high levels of abundance. For the four pairs of species that feed on anchovy and sardine, those in the Humboldt system all have a biology that enables them to increase more rapidly than their Benguela counter-parts. This reflects the higher frequency of environmental perturbations that depress seabird populations in the Humboldt system. In addition, both systems have a small endemic cormorant that feeds near the coast and a small endemic tern that breeds in the adjacent mainland desert and feeds at the sea surface. Several seabirds endemic to a system have no obvious ecological equivalent in the other system: the pelican, a diving-petrel, four storm-petrels and a gull in the Humboldt system; a cormorant and a gull in the Benguela system. Some species with tropical or subantarctic affinities breed at the boundaries of the systems. Others breed also in freshwater systems. The grey gull Larus modestus, which feeds in the Humboldt system, breeds in montane deserts.     

The geological significance of kelp-rafted rock along the west coast of South Africa

Angular to well-rounded pebbles and cobbles have been observed along the southwest coast of South Africa, attached to holdfasts of three species of kelp:Ecklonia maxima, Laminaria pallida, andLaminaria schinzii. A kelp-rafted clast has been dredged from the outer shelf and other clasts have been observedin situ in up to 5 m of water near Cape Town. The clasts have been found on both rocky and sandy shores as well as in a large backshore lagoon on the exposed Atlantic coast of the Cape Peninsula. Isolated clasts in a mid-Holocene lagoon were probably rafted ashore during winter storms in the mid-Holocene.     

Do predatory fish of benthic crustaceans vary between kelp and barren reef habitats in northeastern New Zealand?

Fish assemblages that included known predators of benthic crustaceans were compared between kelp and barren habitats in northeastern New Zealand using baited underwater video census methods. The benthic-feeding fish were observed in winter, spring/summer and autumn, as well as during night-time in spring/summer. Overall, the fish assemblages varied between barren and kelp habitat, being most marked in winter. Individual benthic-feeding species, such as grey mao mao (Scorpis lineolatus) and leatherjacket (Meuschenia scaber) were associated with barren habitat, while the spotted wrasse (Notolabrus celidotus) was more strongly associated with kelp habitat. The results suggest that changes in habitats on coastal reefs affect populations of species that are benthic predators, which may in turn influence the distribution and abundance of their prey species, such as juvenile spiny lobsters.     

Diatoms associated with two South African kelp species: Ecklonia maxima and Laminaria pallida

Kelp forests are believed to host a large biomass of epiphytic fauna and flora, including diatoms, which constitute the base of aquatic food webs and play an important role in the transfer of energy to higher trophic levels. Epiphytic diatom assemblages associated with two common species of South African kelps, Ecklonia maxima and Laminaria pallida, were investigated in this study. Primary blades of adult and juvenile thalli of both kelp species were sampled at False Bay in July 2017 and analysed using scanning electron microscopy. Our findings showed that both kelp species hosted relatively low densities of diatoms (ranging from 7 [SD 5] cells mm^?2 on adult specimens of L. pallida to 43 [SD 66] cells mm^?2 on blades of juvenile E. maxima), with Amphora and Gomphoseptatum reaching the highest absolute abundances. Although non-metric multidimensional scaling showed overlapping and largely scattered sample sets, a significant relationship between the diatom communities and the species and age of the host macroalga was detected by two-way PERMANOVA. In general, more abundant and diverse diatom communities were observed on juvenile thalli than on adult thalli, with species belonging to Navicula and Rhoicosphenia contributing significantly to the observed dissimilarity. Due to a significant interaction between species and age effects, however, the overall ability of kelp species, their age, and their interaction to explain the variation in diatom community structure was limited. We suggest that the low densities of epiphytic diatoms were directly related to the sloughing of epithelial cells observed in both kelp species. We further speculate that on such unstable substrata some diatom taxa might adapt to an endophytic life to avoid the antifouling mechanisms developed by their hosts.     

Community structure of infaunal macrobenthos around vestimentiferan thickets at the San Clemente cold seep,NE Pacific

The San Clemente cold seep lies within 100–200 km of other reducing habitats in the NE Pacific, offering an opportunity to compare diversity and species overlap among reducing habitats (i.e. whale‐, kelp‐, and wood‐falls) at similar depths within a single region. Video observations from the research submersible Alvin at the San Clemente seep (1800 m depth) indicated clumps (‘thickets’) of vestimentiferans distributed as meter‐scale patches interspersed with vesicomyid clam beds and black sediments. Sediment‐core samples were collected at distances of 0 to 80–200 m along randomly oriented transects radiating outward from vestimentiferan thickets to evaluate changes in macrofaunal community structure from thickets into the background community. Macrofaunal abundance was elevated at distances of 0–1 m compared to 80–200 m (i.e. the ‘background’ community). The tube‐building frenulate worms Siboglinum spp., along with peracarid crustaceans, dominated sediments within 1 m of vestimentiferan thickets. Species diversity was depressed within 1 m of thickets but with high rates of species accumulation, suggesting that seep sites greatly increase sediment heterogeneity and facilitate colonization by non‐background macrofaunal species. Stable isotope data indicate chemosynthetic nutrition for some dominant macrofaunal species within 1 m of tubeworm thickets. The macrofaunal community near vestimentiferan thickets in San Clemente seep contains intermediate levels of species richness and diversity compared to other deep‐sea seep areas in the northeast Pacific. There was low species overlap between the San Clemente seep macrofauna and communities in reducing habitats near wood‐, whale‐, and kelp‐falls at similar depths within the region, suggesting that seeps harbor a distinct infaunal community.     

不同饵料对两种帘蛤科贝类生长性能的影响研究

为探讨不同饵料对青蛤(Cyclina sinensis)与文蛤(Meretrix meretrix)生长和存活的影响,本实验选用紫菜(Pyropia)、浒苔(Enteromorpha prolifera)、海带(Laminaria japonica)、小球藻(Chlorella vulgaris)和人工配合饲料5种饵料,采用单一饵料投喂方式进行饲养.结果表明:小球藻组中特定生长率、存活率及饲料转换率与各饵料组均有显著性差异(P<0.05),青蛤的增质量率显著低于紫菜组、海带组及人工配合饲料组(P>0.05).在人工配合饲料组中青蛤与文蛤的特定生长率与各饵料组均有显著性差异(P<0.05),青蛤的增质量率与各饵料组无显著性差异(P>0.05),文蛤的增质量率显著高于紫菜组、浒苔组及人工配合饲料组(P<0.05).在3组大型藻中,海带组中青蛤的特定生长率为0.07％,增质量率为4.59％,饵料转换率为7.09％,存活率为74％;文蛤的特定生长率0.13％,增质量率为8.36％,饵料转换率为1.41％,存活率为55.6％.综上,小球藻和人工配合饲料有利于青蛤和文蛤的生长,在3组大型藻中,投喂海带有利于文蛤和青蛤的生长和存活.     

The rise of Laminaria ochroleuca in the Western English Channel (UK) and comparisons with its competitor and assemblage dominant Laminaria hyperborea

The distribution of species is shifting in response to recent climate change. Changes in the abundance and distributions of habitat‐forming species can have knock‐on effects on community structure, biodiversity patterns and ecological processes. We empirically examined temporal changes in the abundance of the warm‐water kelp Laminaria ochroleuca at its poleward range edge in the Western English Channel. Resurveys of historical sites indicated that the abundance of L. ochroleuca has increased significantly in recent decades. Moreover, examination of historical records suggested that L. ochroleuca has extended its distribution from sheltered coasts on to moderately wave‐exposed open coasts, where it now co‐exists and competes with the assemblage dominant Laminaria hyperborea. Proliferation of L. ochroleuca at its poleward range edge corresponds with a period of rapid warming in the Western English Channel. Preliminary comparisons between L. ochroleuca and L. hyperborea highlighted some subtle but ecologically significant differences in structure and function. In summer, the average biomass of epiphytic stipe assemblages on L. hyperborea was 86 times greater than on L. ochroleuca whereas, on average, L. ochroleuca had a greater stipe length and its blade supported 18 times as many gastropod grazers (Gibbula cineraria). Differences in summer growth rates were also recorded, with L. ochroleuca being more productive than L. hyperborea throughout July. Comprehensive seasonally replicated comparisons are needed to examine the wider implications of proliferation of L. ochroleuca at its poleward range edge, but our study suggests that local biodiversity patterns and ecological processes (e.g. timing of productivity and trophic pathways) on shallow subtidal reefs may be altered by shifts in the relative abundances of habitat‐forming kelp species.     

海带褐藻多酚对绿烂海带表面分离的一株细菌的抑菌效果研究

海带苗绿烂病暴发严重威胁海带养殖生产,给海带养殖业造成巨大经济损失.研究发现,海带中的多酚化合物可以抵御海带病害初期病原体侵入.为研究多酚对绿烂海带表面附生菌的抑菌效果,在病烂部位分离出一株细菌,通过16s rRNA基因测序的方法,证实该细菌为小孔芽孢杆菌(Bacillus foraminis).进一步以健康海带为原料...     

The biogeography and community structure of kelp forest macroinvertebrates

Understanding species distributions and their community structure is increasingly important when taking an ecosystem‐based approach to conservation and management. However, knowledge of the distribution and community structure of species in mid‐range trophic levels (e.g. macroinvertebrates) is lacking in most marine ecosystems. Our study aimed to examine the spatial distribution and community‐level biogeographic patterns of common kelp forest–rocky reef macroinvertebrates in Southern California and to evaluate the effects of environmental gradients on these communities. Quantitative SCUBA surveys were used to estimate macroinvertebrate densities at 92 sites from 2008–2012. Non‐metric multidimensional scaling was used to evaluate spatial patterns of macroinvertebrate communities among Regions. We found that kelp forest–rocky reef macroinvertebrate communities are distinct among different island and mainland regions, and their community patterns exhibited a strong relationship with an environmental gradient (i.e. sea surface temperature) even after controlling for geographic distance between sites. High abundances of urchin species (Strongylocentrotus purpuratus and Strongylocentrotus franciscanus) were strong drivers of regional differences. Macroinvertebrate community patterns were driven by characteristic species that were typically more prevalent at warmer or colder sites. Our results provide the first quantitative analysis of macroinvertebrate community structure within the California kelp forest ecosystem. We also describe the distribution and abundance of 92 conspicuous kelp forest‐rocky reef macroinvertebrates among nine pre‐defined Regions. This study provides important preliminary information on these macroinvertebrate species that will be directly useful to inform management of invertebrate fisheries and spatial protection of marine resources.     

First survey of fishes in the Betty's Bay Marine Protected Area along South Africa's temperate south-west coast

This first survey of fish in the Betty's Bay Marine Protected Area (MPA), on the south coast of South Africa, was conducted using baited remote underwater video systems (BRUVs). A total of 58 deployments recorded 42 species in 20?km², including reef, kelp and sand habitats in protected and exploited zones, at between 5 and 40?m depth. Chondrichthyans accounted for 28% of diversity. Teleost diversity was dominated by Sparidae, Cheilodactylidae, Sciaenidae and Ariidae. Diversity (H′) was highest in kelp and lowest over sand. Species composition differed among habitat and depths, but protection had no effect. Among four commercial species, only Pachymetopon blochii responded positively to protection. The apparent failure of protection may attest to poor compliance, but an investigation into fish size might show an effect. Many species were detected at the western extreme of their range. Diversity in Betty's Bay was predictably lower than in the more eastward Stilbaai MPA, but also lower than in the westward Table Mountain National Park MPA. Fish diversity did not follow a linear increase eastwards from Cape Point. Betty's Bay includes the most easterly protected kelp forests and contains seven species not recorded in the other two areas, and is therefore an important element in the MPA network.     

2021～2022年荣成海域多相赤潮的分子鉴定

山东半岛濒临渤海和黄海,海岸带复杂,海岸线长,近岸海域赤潮事件频发。然而,由于部分赤潮物种的形态难以识别,或易降解不稳定,加上形态鉴定专业要求高,导致致灾赤潮物种未得到准确鉴定。2021年11月至2022年4月间山东荣成海域海带养殖区暴发严重赤潮事件,面积达1 440 km²,导致海带白化、溃烂,造成严重经济损失。对该海域水样固定样本的观察鉴定到两种致灾赤潮物种,红色赤潮藻(Akashiwo sanguinea)和多纹膝沟藻(Gonyaulax polygramma),二者均为山东近海常见的致灾赤潮物种。该研究通过对赤潮样本中活体单细胞的显微观察和单细胞测序分析,根据藻细胞形态特征与分子标记序列相似性鉴定到三种优势致灾赤潮物种,包括红色赤潮藻、多纹膝沟藻和灰白下沟藻(Katodinium glaucum)。其中灰白下沟藻由于在固定过程中不稳定而较少得到鉴定。对该赤潮海域水样开展宏条形码分析,除了发现上述三种致灾赤潮物种外,还发现了另外一个致灾赤潮物种纺锤环沟藻(Gyrodinium fusiforme)。纺锤环沟藻也由于在固定过程中不稳定而较少得到鉴定。由此可见,...     

山东荣成临洛北湾夏季大型底栖动物群落生态学初步研究

利用2010年7月在山东荣成临洛北湾所获得大型底栖动物定量分析资料,研究了夏季该海域海带养殖区和邻近水域大型底栖动物在物种组成、生物量、丰度、优势种以及物种多样性等方面的特征和空间差异,并采用MDS和CLUSTER分析了大型底栖动物的群落结构,以期为该地区以后的科学研究提供基础数据.结果表明,本次调查通过采泥和拖网共采集到大型底栖动物88种,其中采泥得到大型底栖动物51种,拖网采得大型底栖动物45种,各站位的物种多样性差异明显,物种数量从2种到21种.与环境因子的相关性分析显示,各站的物种数和丰度与DO存在明显的负相关.在所有大型底栖动物中,甲壳动物26种,多毛类环节动物24种,软体动物23种,棘皮动物8种,其他类群动物6种(鱼类5种,尾索动物1种).该海域的优势种为多丝独毛虫和短叶索沙蚕.将CLUSTER结果以43%的群落结构相似性来划分,组内的相似性为50%~60%.该海域大型底栖动物的平均丰度为854个/m2,平均生物量为134.73 g/m2,与研究海域附近的历史研究结果相比较,该海域的平均丰度和生物量仍处于较高的水平.     

Use of submerged aquatic vegetation as habitat by young-of-the-year epibenthic fishes in shallow Maine nearshore waters

Epibenthic fishes were collected with daytime beam trawl tows (n = 1713) in three shallow (<10 m) habitats of submerged aquatic vegetation (SAV), Zostera marina (eelgrass), Laminaria longicruris (kelp), Phyllophora sp. (algae), and unvegetated sandy/mud areas. We divided the Maine coast into three broad zones based upon geological features and sampled over five consecutive years; during April–November 2000 in the mid coast, in 2001 and 2002 along the south coast and in 2003 and 2004 along the eastern Maine coast. We quantified habitat use by eight economically important fish species (Gadus morhua, Microgadus tomcod, Pollachius virens, Urophycis chuss, Urophycis tenuis, Osmerus mordax, Tautogolabrus adspersus, and Pseudopleuronectes americanus) and 10 other common epibenthic species (n = 18 571). We identified the physical and biological variables most important in discriminating between habitats with and without individual fish species. Logistic regression models based on nearshore habitat characteristics were developed to predict the distribution of these species along the three zones representing broad geological regions of the Maine coast. Logistic regression models correctly classified individual fish species 58.7–97.1% of the time based on the temporal and physical habitat variables (month, temperature, salinity, and depth) and the presence–absence of submerged aquatic vegetation (Zostera, Laminaria, or Phyllophora). Overall fish presence and economically important fish presence were correctly classified 61.1–79.8% and 66.0–73.6% of the time, respectively. The Maine shallow water fish community was composed primarily of young-of-the-year and juvenile fishes with all habitats functioning as facultative nursery areas. Presence of most fish species was positively associated with Zostera, Laminaria, and to a lesser extent, Phyllophora. This study provides direct evidence of shallow waters of the Gulf of Maine as critical facultative nursery habitat for juvenile G. morhua, M. tomcod, P. virens, U. tenuis, U. chuss, T. adspersus, O. mordax and P. americanus, and many ecologically important species.     

Growth pattern and changes in abundance of the endangered bat star Asterina stellifera

The sea star Asterina stellifera has declined during the last decade and is currently abundant only in the southern limit of its former range. We surveyed this population over 5 years to model individual growth and explore the relationship of changes in local abundance with variation in environmental factors and the reproductive status of individuals. Our results show that A. stellifera is a species with slow growth and a relatively long lifespan. Contrary to expectations for temperate species, growth rates were fairly constant through the year and therefore models including seasonal oscillations were inappropriate. The abundance of this species increased significantly from early spring to early summer, likely due to augmented activity and small‐scale aggregation during the reproductive season that affected our estimates of abundance. No significant recruitment occurred during the 5 years studied. The lack of recruitment during long periods and the slow individual growth rates make A. stellifera particularly vulnerable to local extinction. This study was performed prior to the arrival in the study area of the invasive kelp Undaria pinnatifida and side‐gilled sea slug Pleurobranchaea maculata, species that threaten the community structure where A. stellifera lives. Therefore, the information reported here will be essential to assessing the impacts of these exotic species on this sea star population.     

Repeat photography as a tool for detecting and monitoring historical changes in South African coastal habitats

Repeat photography was used to illustrate long-term changes occurring in coastal habitats in the Western Cape, South Africa. Historic images were sourced from books and theses, the public and subject specialists, and repeat photographs were then taken from the same perspectives. Visible changes could be categorised into four types: (1) changes in species’ ranges; (2) biological invasions; (3) sea level changes; and (4) direct engineering impacts. In terms of range changes, the images depict a progressive easterly spread of the cold-water kelp Ecklonia maxima and parallel easterly contraction of the warmer-water mussel Perna perna, both evidence for declining water temperatures along the South-West Coast. Since c. 1980 most shores have also become conspicuously invaded by the alien Mediterranean mussel Mytilus galloprovincialis, while those on the West Coast have also been visibly invaded by the more-recently introduced Pacific barnacle Balanus glandula. No changes in vertical zonation due to changing sea levels could be detected, despite suitable images being available. Construction along the shore has radically altered the appearance of the shoreline in urban areas. Repeat photography thus proved a useful tool for both detecting and dramatically illustrating historic changes over the past century. These changes have altered substantially both the appearance and ecological attributes of many rocky shores in this region.     

Influence of an oxygen minimum zone and macroalgal enrichment on benthic megafaunal community composition in a NE Pacific submarine canyon

Megafaunal diversity in the deep sea shows a parabolic pattern with depth. It can be affected by factors such as low oxygen concentration, which suppresses diversity, or the presence of submarine canyons, which enhances it. Barkley Canyon, located off the west coast of British Columbia, Canada, is a submarine canyon that extends from the continental margin (200 m) into the deep ocean (2,000 m). This canyon receives drift kelp from shoreline kelp forests and contains an oxygen minimum zone (OMZ) at 500 to 1,500 m depth. Our study investigated the abundance and diversity of epibenthic megafauna over a range of depths (200–2,000 m) and oxygen concentrations (0.5–5.0 ml/L) within Barkley Canyon, as well as changes in abundance near detrital kelp. Video was collected using the remotely operated vehicle ROPOS along seven 1‐km cross‐canyon (i.e., across the axis of the canyon) transects and three 40‐m perpendicular cross‐transects over kelp. Taxonomic groups were associated with depth, temperature, and the presence of pebbles. The OMZ restricted pennatulids, and edge effects along OMZ boundaries were observed for ophiuroids. The geomorphology of the sea floor affected the distribution of taxa across the canyon, with Porifera mainly found along the walls and Echinoidea within the canyon axis. Expected richness exhibited a bimodal pattern, peaking at 300 and 2,000 m, possibly due to the combined effect of the OMZ and the submarine canyon. Echinoidea aggregated near drift kelp at 200 and 300 m. We found that faunal communities in Barkley Canyon were influenced by several confounded factors including depth, oxygen and substrate. Understanding faunal patterns is paramount with increased exploitation and a changing climate.     

Effect of the kelp Laminaria hyperborea upon sand dune erosion and water particle velocities

This paper presents a set of results from a laboratory study on water wave propagation above submerged vegetation growing in the surf zone and the effect of submerged vegetation on dune erosion. The study has focused on the kelp Laminaria hyperborea. The reason is that this kelp is commercially harvested along the Norwegian coast and there is a need to obtain better knowledge on the possible consequences of this harvesting. Experiments were run with irregular waves over a sloping bottom, and a kelp field was simulated by 5000 artificial kelp plants in a 1:10 scale. The experiments primarily focused on the effect of kelp upon erosion of a sand dune, wave damping and water velocities. It was found that the water level is a very important factor to the degree of dune erosion, while the kelp has only a minor effect. The kelp does, however, cause significant wave damping and the degree of wave breaking is reduced. It was also found that the kelp modifies the water velocity profile. In a region above the kelp canopy layer, the time-averaged water velocity was shoreward, while the seaward undertow was confined to a region higher up in the water column.