Distribution Of Macroalgae Research Articles

Antarctic intertidal macroalgae under predicted increased temperatures mediated by global climate change: Would they cope?

The Antarctic Peninsula is one of the regions to be most affected by increase in sea surface temperatures (SSTs) mediated by Global Climate Change; indeed, most negative predictions imply an up to 6 °C increment by the end of the XXI century. Temperature is one of the most important factors mediating diversity and distribution of macroalgae, although there is still no consensus as to the likely effects of higher SSTs, especially for polar seaweeds. Some available information suggests that potential strategies to withstand future increases in SSTs will be founded upon the glutathione-ascorbate cycle and the induction of chaperone-functioning heat shock proteins (HSPs); however, their eventual role, even for general stress responses, is unclear. The intertidal green, brown and red macroalgae species Monostroma hariotii, Adenocystis utricularis and Pyropia endiviifolia, respectively, from King George Island, Antarctic Peninsula, were exposed to 2 °C (control) and 8 °C (climate change scenario) for up to 5 days (d). Photosynthetic activity (αETR and ETRmax, and EkETR), photoinhibition (Fv/Fm) and photoprotection processes (αNPQ, NPQmax, and EkNPQ) provided no evidence of negative ecophysiological effects. There were moderate increases in H2O2 production and levels of lipid peroxidation with temperature, results supported by stable levels of total glutathione and ascorbate pools, with mostly higher levels of reduced ascorbate and glutathione than oxidized forms in all species. Transcripts of P. endiviifolia indicated a general upregulation of all antioxidant enzymes and HSPs genes studied under warmer temperature, although with different levels of activation with time. This pioneering investigation exploring different levels of biological organization, suggested that Antarctic intertidal macroalgae may be able to withstand future rise in SSTs, probably slightly altering their latitudinal distribution and/or range of thermal tolerance, by exhibiting robust glutathione-ascorbate production and recycling, as well as the induction of associated antioxidant enzymatic machinery and the syntheses of HSPs.

Seasonal and spatial variations of macrobenthic community in intertidal Sargassum field off Naozhou Island, South China Sea

Seasonal and spatial variations in the macrobenthic community in an intertidal gulfweed field off Naozhou Island were investigated from April 2011 to January 2012. We identified 407 macrobenthic organism species: 64 macroalgae (15.72% of total species); 123 Arthropoda (30.22%); 107 Mollusca (26.29%); 67 Annelida (16.46%); 15 Cnidaria (3.69%); 14 Echinodermata (3.44%); 8 Porifera (1.97%); 4 Chordata (0.98%); 2 Urochorda (0.49%); and 1 each of Echiura, Sipunculida and Angiospermae (0.25%). Arthropods, mollusks, annelids, and macroalgae were four main groups in the benthic organism community and accounted for 88.70% of the total species. In terms of abundance of biomass, there were 15 dominant species, including 8 macroalgal, 5 mollusk and 2 arthropod species. The species diversity indices ranged from 1.21 to 4.42 with an average of 2.80; the annual average of evenness was 0.47. Species richness indices varied from 2.97 to 7.24 (average 4.97); and Simpson dominance indices varied from 0.20 to 0.92 in annual average of 0.75. Macroalgal distribution showed clear vertical zonation and seasonal changes. The number of macroalgal species found in the high tide zone, upper middle tide zone, middle tide zone, lower middle tide zone, low tide zone, and below low tide zone were 1, 8, 10, 16, 22, and 32, respectively. Biomass among the benthic organisms, macroalgae and crustaceans had significant positive correlation (P<0.05) with the coefficients of 0.802, 0.894, and 0.592, respectively. Macroalgal biomass showed a clearly negative correlation with the concentration of dissolved inorganic nitrogen (DIN) (R=0.486, P<0.05). During the winter and spring, when macroalgae were growing vigorously, DIN reached the lowest level in seawater and displayed a clear weak correlation between macroalgal growth and the nutrient concentration.

Diversity and Distribution of Macroalgae in Beralas Bakau Island, Gunung Kijang District, Bintan Regency

Bintan Regency have potential aquatic resources which have ecologically important value, one of these resources is macroalgae or seaweed. The objective of this study was to determine the composition of species, density, distribution patterns and environmental factors that influence the presence of macroalgae in the waters of the Beralas Bakau island. This research was conducted with a random method of 30 points using a 2x2 m plot. The results of the study found 7 types of macroalgae namely, Acanthophora spicifera, Caulerpa lentillifera, Gracilaria Salicornia, Halimeda opuntia, Kappaphycus cottonii, Padina australis, and Sargassum cristaefolium. The highest density was Sargassum cristaefolium (34.75 ind/m²) and the lowest was H. opuntia (0.25 ind/m²) with a total overall value of species density 51.25 ind/m². The distribution pattern value was uniform with a value of -2.843. Based on the results obtained from the Principal Component Analysis (PCA), the relationship between phosphate parameters and pH was more closely related to the density of macroalgae types compared with other chemical physics parameters

Whole community estimates of macroalgal pigment concentration within two southern New Zealand kelp forests1.

Light availability is a fundamental factor that controls the productivity and distribution of macroalgae and is highly variable, both spatially and temporally, in subtidal coastal systems. Our comprehension of how macroalgae respond to such variability is a significant knowledge gap that limits our understanding of how light influences the structure and productivity of these environments. Here, we examined the pigment characteristics of individual species, and for the first time the whole community, within one low-light, and one high-light kelp-forest system in southern New Zealand. The aim was to quantify the range of pigmentation seen within the two kelp-forests which differed in irradiance regime. Light availability was 33% and 64% greater at the high-light compared to the low-light site at 2 and 10m depth, respectively. Results suggested Phaeophyceae species at deeper depths in the low-light site may be living at the edge of their photosynthetic ability and pigment synthesis appeared significantly restricted. Even with greater investment in the pigment fucoxanthin, biomass of Phaeophyceae species was significantly lower in the low-light site. Highly pigmented Rhodophyceae species made a greater proportional contribution to community biomass within the low-light site where they likely possessed a photosynthetic advantage. This work helps explain discrepancies in community structure between the two study sites and explores the complex relationship between irradiance and photoacclimation. The comparison of community pigment concentration holds potential as a tool for assessing the relative degree of photoacclimation occurring between sites and provides a proxy of photosynthetic cost under a specific light regime.

Ensemble Modeling of Antarctic Macroalgal Habitats Exposed to Glacial Melt in a Polar Fjord

Macroalgae are the main primary producers in polar coastal regions and of major importance for the associated heterotrophic communities. On King George Island/Isla 25 de Mayo, West Antarctic Peninsula (WAP) several fjords undergo rapid glacial retreat in response to increasing atmospheric temperatures. Hence, extended meltwater plumes laden with suspended particulate matter (SPM) are generated that hamper primary production during the austral summer season. We used ensemble modeling to approximate changes in the benthic productivity of an Antarctic fjord as a function of SPM discharge. A set of environmental variables was statistically selected and an ensemble of correlative species-distribution models was devised to project scattered georeferenced observation data to a spatial distribution of macroalgae for a “time of measurement” (“tom”) scenario (2008-2015). The model achieved statistically reliable validation results (true scale statistics 0.833, relative operating characteristics 0.975) and explained more than 60% of the modeled macroalgae distribution with the variables “hard substrate” and “SPM”. This “tom” scenario depicts a macroalgae cover of approx. 8% (63 ha) for the total study area (8 km2) and a summer production of approximately 350 t dry weight. Assuming a linear increase of meltwater SPM load over time, two past (1991 and 1998) and two future (2019 and 2026) simulations with varying SPM intensities were applied. The simulation using only 50% of the “tom” scenario SPM amount (simulating 1991) resulted in increased macroalgal distribution (143 ha) and a higher summer production (792 t) compared to the “tom” status and could be validated using historical data. Forecasting the year 2019 from the “tom” status, an increase of 25% SPM results in a predicted reduction of macroalgae summer production to approximately 60% (141 t). We present a first quantitative model for changing fjordic macroalgal production under continued melt conditions at WAP. As meltwater influenced habitats are extending under climate change conditions, our approach can serve to approximate future productivity shifts for WAP fjord systems. The reduction of macroalgal productivity as predicted for Potter Cove may have significant consequences for polar coastal ecosystems under continuing climate change.

An affordable and portable autonomous surface vehicle with obstacle avoidance for coastal ocean monitoring

Abstract Bathymetry measurements are needed in shallow, near-shore environments to estimate the potential distribution of macroalgae and seagrass, which contribute to oceanic carbon sinks in Greenland and other Arctic locations. Additionally, ocean current observations near icebergs and marine-terminating glaciers are necessary to estimate their melt rates. Rocky coastlines, icebergs and glaciers, however, present a significant safety risk to manned vessels. We developed an affordable and portable autonomous surface vehicle (ASV) that can safely obtain bathymetry and ocean current measurements in dangerous environments. The Arctic Research Centre Autonomous Boat (ARCAB) is a student-built ASV that can be transported on a euro-pallet and operated from a small boat and from shore. ARCAB has a minimum battery life of 2 h and accommodates a SonTek M9 RiverSurveyor system for bathymetry and ocean current measurements. ARCAB is controlled by a National Instruments myRIO-1900 and features autonomous waypoint navigation, obstacle avoidance, and return-to-home functionality. We demonstrate the use of ARCAB in Greenland in January 2019.

Survey of the Seaweeds of the Beach of Pina, Recife Pernambuco

The constant interference of human activities has had direct and indirect impacts on aquatic environments with consequences for water quality for aquatic biota and the functioning of ecosystems, thereby reducing the ability to use. This study aimed to describe the qualitative and quantitative variation of species of macroalgae from Praia do Pina, Recife-PE, in the rainy season and drought. The collections were made in August 2007 (rainy season) and January 2008 (period of drought). Data on the occurrence of macroalgae were collected by snorkeling using the combined techniques of sampling belt transects (50m x 1m) and quadrats (1m x1m). The species of greatest abundance in both periods were almost the same: Ulva lactuca, U. fasciata, U. intestinalis, Caulerpa sertularioides, C. filiformis; C.prolifera; C.racemosa, and C. lentillifera; being found in smaller quantities: Pterocladia capillaceous, Hypnea musciformis, H. pannosa, H. cervicornis, Sargassum Muticum, S. vulgare, S. ilicifolium, Padin Pavoni, P. tetrastromatica, Dictyota dichotoma, Gracilaria warts and G. Salicornia. The two species were only found in Glacilaria period of drought and the species S. ilicifolium was found during the rainy season. About 80% of macroalgal distribution in reef studied is composed of individuals belonging to the phylum Chlorophyta, 12% are representatives of the phylum Phaeophyta and 8% are belonging to the phylum Rodhophyta. These percentages are very close to the values presented in two urban beaches in the Metropolitan Region of Recife and a beach on the northern coast of the state of Pernambuco, where areas have been intensified the processes of human occupation and exploitation, and increasing industrialization. The predominance of species of Chlorophyta may represent a greater tolerance to the flora of the pollutants.

Substrate limitation of a habitat-forming genus Fucus under different water clarity scenarios in the northern Baltic Sea

Canopy-forming macroalgae living on rocky bottoms provide valuable ecosystem services but long-term eutrophication has narrowed their distribution and depth zonation in the Baltic Sea. The spatial distribution of macroalgae is shaped by many factors, such as light, salinity, nutrients and wave exposure. In addition, the lack of suitable hard substrates limits the distribution of algae in many areas. Analysing how the spatial distribution of macroalgae is modified by changes in environmental conditions is relevant for focusing management actions. To quantify the resultant distribution under various environmental and management scenarios, both current environmental conditions and substrate limitation need to be considered. We estimated the potential distribution area of bladderwrack Fucus spp. under 11 water transparency scenarios in 9 Finnish sea areas differing in morphology and eutrophication status. The prevailing averaged long-term water transparency conditions were interpreted from satellite images. Ten scenarios were calculated based on hypothetical changes in euphotic depth from −50% to +50% of the present. Species distribution modelling was used to assess the potential distribution areas of Fucus. In addition, to quantify the influence of substrate limitation, we estimated the average substrate limitation with two correction methods: (i) by using field data from underwater videos within the predicted distribution areas and (ii) by using a habitat model representing the distribution of reefs (i.e. rocky bottoms) in the study area. The decrease of euphotic depth by 50% from the present level narrowed the distribution area of Fucus by 24–53% in the Southwestern archipelago, 55–70% in the Gulf of Finland, 37–66% in the Bothnian Sea and 59–100% in Kvarken. An increase in euphotic depth significantly broadened the spatial distribution of Fucus. Decreasing share of suitable hard substrate along depth gradient however hinders broadening of the distribution area. If all areas were suitable for growth, a 50% increase in euphotic depth would expand the distribution area by 124–803%, depending on area. When only suitable substrates were taken into account, this percentage remained at 9–270%. We conclude that substrate limitation needs to be taken into account when estimating macroalgal species distribution in the marine environment. We show how this can be done also when comprehensive bottom substrate maps are not available. Our results are valuable when setting the targets for environmental management plans, and for balancing the local management measures in a cost effective manner.

The importance of macroalgae and associated amphipods in the selective benthic feeding of sister rockcod species Notothenia rossii and N. coriiceps (Nototheniidae) in West Antarctica

Studies on feeding selectivity in Antarctic fish with comparison between diet organisms and those available in the wild are scarce. We explored this issue in Notothenia rossii (NOR) and N. coriiceps (NOC) at Potter Cove in summer 2016 to test: (1) their preference among different benthic groups, primarily species of algae and amphipods and (2) differences between these nototheniids given their distinct morphology but their known similar general ecology in the fjords. The methodology included a comparative analysis of benthic organisms identified in the stomachs and those collected on macroalgal beds (Ivlev Index). Benthic amphipods, mainly Gondogeneia antarctica and Cheirimedon femoratus, followed by macroalgae, mainly Palmaria decipiens and Desmarestia spp., were the most important and frequent dietary items (IRI%) for both nototheniids. However, NOC was more herbivorous and fed more intensively on a wider diversity of benthic organisms such as certain algal-associated groups like gastropods and bivalves, whereas NOR fed on a greater proportion of epibenthic amphipods and other epibenthic prey. Although in the last three decades the physiognomy of the inner cove has been changed due to the retreat of the Fourcade Glacier, at our sampling site in the outer cove the abundance and vertical distribution of macroalgae did not show substantial changes compared with those reported in the literature in 1994–1996. Temporal differences in the feeding selectivity of NOC on amphipod species, between contemporary and historical samples, may be explained by variations in the assemblage of the algal-associated epifauna. We suggest factors that may have produced these changes.

Engineering protein nanocages for targeted photodynamic therapy

Seaweed beds are a nearshore marine ecosystem composed of macroalgae and other marine organisms. In recent years, soil erosion, pollution, and other land-based mechanisms have severely reduced nearshore algal populations, particularly in areas influenced by the outflow of the Yangtze and Qiantang rivers. The Ma'an Archipelago is located in the estuary of the Yangtze and Qiantang rivers in the East China Sea. Although the archipelago is relatively distant from the shore, algal populations there have decreased significantly in recent years. The reasons for this decline are unknown, owing to an absence of data on macroalgal spatial distribution in seaweed beds and of long-term monitoring. Numerous environmental factors, operating at different scales, are likely to contribute to the abundance and distribution of macroalgae in seaweed beds. Therefore, it is important to study the beds across spatial scales to understand the ecological factors influencing the beds' presence and decline. During September 2014 and May 2015, we investigated the distribution of Sargassum horneri in germling and adult stages at 12 sites on three islands (Zhongkui, Lvhua, and Gouqi) around the Ma'an Archipelago. Our results showed that: (1) on a whole-archipelago scale, S. horneri density was highest around Zhongkui Island, and lowest around Lvhua Island. Adult plant lengths showed the opposite trend. The ratio of average densities around the three islands was 1 (Lvhua): 3.8 (Gouqi): 13.8 (Zhongkui) at the germling stage, and changed to 1:1.8:4 at the adult stage. (2) At the individual-site scale, wave exposure may explain why S. horneri density is highest in southeastern sites and lowest in northwestern ones. Around Zhongkui Island, S. horneri grew in turbulent conditions, was significantly affected by wave motion, and suffered a high mortality rate between the seedling and adult stages. (3) Within site scale, S. horneri was distributed over a considerably wider depth range around Zhongkui Island than around Lvhua or Gouqi islands. Adult S. horneri was most abundant at 2-m depth. Wave action apparently controlled the upper limit of S. horneri bathymetric distribution, whereas the lower limit depended on sedimentation and light availability.

Study of Macroalgae Biodiversity in the western Algerian Coast, Tenes

During this study we evaluated the spatio-temporal distribution of macroalgae in the western Algerian coast. This work was carried out in the intertidal zone near the municipality of Tenes. We carried out a seasonal sampling from July 2016 to April 2017, at four different sites. Nine species were identified. The highest species richness was observed in summer and early autumn. The most abundant algae observed were Ulva et Cystoseira. Ulva alga achieved the highest recovery rate 60,33% in Spring. Laurencia obtusa and Spongomorpha arcta were the least abundant. Algae of economic interest have been observed in the coast of Tenes.

Density, abundance and extractive potential of the mangrove crab, Ucides cordatus (Linnaeus, 1763) (Brachyura, Ocypodidae): subsidies for fishery management

Ucides cordatus is a relevant fishery resource of Brazilian mangroves and requires legal normative to sustainable use based on stock assessment and management. This study evaluated some population parameters (structure, density, abundance, fishery potential and stock) of this crab species in Brazil Southeast (São Paulo, State), discussing the use of the results to delineate fishery management strategies. Density was monthly evaluated (September 1998 to August 1999), using five sample quadrats of 2x2 m. Density (ind.m-2) was indirectly estimated by counting the opened (with biogenic activity) and closed galleries, and contrasted with flooding level by tides using the vertical distribution of macroalgae in the base of trees. Density of U. cordatus ranges from 2 to 11 ind.m-2 (6±2 ind.m-2) and statistical difference occurred among monthly means (F=11.58; p=0.000). The relationship density vs. tidal flooding indicated a decrease of U. cordatus density in mangroves with higher levels of tidal flooding (r=-0.94; p=0.001). The total abundance of U. cordatus was estimated in 63.7 millions of crabs in 10.61 km2, with a reduction of 34.9% due to total mortality discount. Estimates like that are uncommon in literature, and could be used for fishery forecasts, allowing improvement by the introduction of new variables to be known in the future.

Spatial distribution patterns of Sargassum horneri in the coastal waters of the Ma'an Archipelago

Seaweed beds are a nearshore marine ecosystem composed of macroalgae and other marine organisms. In recent years, soil erosion, pollution, and other land-based mechanisms have severely reduced nearshore algal populations, particularly in areas influenced by the outflow of the Yangtze and Qiantang rivers. The Ma'an Archipelago is located in the estuary of the Yangtze and Qiantang rivers in the East China Sea. Although the archipelago is relatively distant from the shore, algal populations there have decreased significantly in recent years. The reasons for this decline are unknown, owing to an absence of data on macroalgal spatial distribution in seaweed beds and of long-term monitoring. Numerous environmental factors, operating at different scales, are likely to contribute to the abundance and distribution of macroalgae in seaweed beds. Therefore, it is important to study the beds across spatial scales to understand the ecological factors influencing the beds' presence and decline. During September 2014 and May 2015, we investigated the distribution of Sargassum horneri in germling and adult stages at 12 sites on three islands (Zhongkui, Lvhua, and Gouqi) around the Ma'an Archipelago. Our results showed that: (1) on a whole-archipelago scale, S. horneri density was highest around Zhongkui Island, and lowest around Lvhua Island. Adult plant lengths showed the opposite trend. The ratio of average densities around the three islands was 1 (Lvhua): 3.8 (Gouqi): 13.8 (Zhongkui) at the germling stage, and changed to 1:1.8:4 at the adult stage. (2) At the individual-site scale, wave exposure may explain why S. horneri density is highest in southeastern sites and lowest in northwestern ones. Around Zhongkui Island, S. horneri grew in turbulent conditions, was significantly affected by wave motion, and suffered a high mortality rate between the seedling and adult stages. (3) Within site scale, S. horneri was distributed over a considerably wider depth range around Zhongkui Island than around Lvhua or Gouqi islands. Adult S. horneri was most abundant at 2-m depth. Wave action apparently controlled the upper limit of S. horneri bathymetric distribution, whereas the lower limit depended on sedimentation and light availability.

Spatial distribution patterns of Sargassum horneri in the coastal waters of the Ma'an Archipelago

Seaweed beds are a nearshore marine ecosystem composed of macroalgae and other marine organisms. In recent years, soil erosion, pollution, and other land-based mechanisms have severely reduced nearshore algal populations, particularly in areas influenced by the outflow of the Yangtze and Qiantang rivers. The Ma'an Archipelago is located in the estuary of the Yangtze and Qiantang rivers in the East China Sea. Although the archipelago is relatively distant from the shore, algal populations there have decreased significantly in recent years. The reasons for this decline are unknown, owing to an absence of data on macroalgal spatial distribution in seaweed beds and of long-term monitoring. Numerous environmental factors, operating at different scales, are likely to contribute to the abundance and distribution of macroalgae in seaweed beds. Therefore, it is important to study the beds across spatial scales to understand the ecological factors influencing the beds' presence and decline. During September 2014 and May 2015, we investigated the distribution of Sargassum horneri in germling and adult stages at 12 sites on three islands (Zhongkui, Lvhua, and Gouqi) around the Ma'an Archipelago. Our results showed that: (1) on a whole-archipelago scale, S. horneri density was highest around Zhongkui Island, and lowest around Lvhua Island. Adult plant lengths showed the opposite trend. The ratio of average densities around the three islands was 1 (Lvhua): 3.8 (Gouqi): 13.8 (Zhongkui) at the germling stage, and changed to 1:1.8:4 at the adult stage. (2) At the individual-site scale, wave exposure may explain why S. horneri density is highest in southeastern sites and lowest in northwestern ones. Around Zhongkui Island, S. horneri grew in turbulent conditions, was significantly affected by wave motion, and suffered a high mortality rate between the seedling and adult stages. (3) Within site scale, S. horneri was distributed over a considerably wider depth range around Zhongkui Island than around Lvhua or Gouqi islands. Adult S. horneri was most abundant at 2-m depth. Wave action apparently controlled the upper limit of S. horneri bathymetric distribution, whereas the lower limit depended on sedimentation and light availability.

Spatial distribution of macroalgae along the shores of Kongsfjorden (West Spitsbergen) using acoustic imaging

AbstractThe identification of macroalgal beds is a crucial component for the description of fjord ecosystems. Direct, biological sampling is still the most popular investigation technique but acoustic methods are becoming increasingly recognized as a very efficient tool for the assessment of benthic communities. In 2007 we carried out the first acoustic survey of the littoral areas in Kongsfjorden. A 2.68 km2area comprised within a 12.40 km2euphotic zone was mapped along the fjord’s coast using single- and multi-beam echosounders. The singlebeam echosounder (SBES) proved to be a very efficient and reliable tool for macroalgae detection in Arctic conditions. The multibeam echosounder (MBES) was very useful in extending the SBES survey range, even though it’s ability in discriminating benthic communities was limited. The final result of our investigation is a map of the macroalgae distribution around the fjord, showing 39% macroalgae coverage (1.09 km2) of investigated area between isobaths -0.70 m and -30 m. Zonation analysis showed that most of the studied macroalgae areas occur up to 15 m depth (93%). These results were confirmed by biological sampling and observation in key areas. The potential of acoustic imaging of macrophytes, and a proposed methodology for the processing of acoustic data, are presented in this paper along with preliminary studies on the acoustic reflectivity of macroalgae, also highlighting differences among species. These results can be applied to future monitoring of the evolution of kelp beds in different areas of the Arctic, and in the rest of the world.

Distribution of macroalgae in Kongsfjorden, Svalbard

Macroalgal distribution varies with prevailing environmental gradients in fjords, particularly in glacial fjords such as Kongsfjorden, Svalbard. This survey by scuba-diving in 1996 and 1998 was the first to determine species composition, dominance and distribution of macroalgae along the entire length axis of a fjord in the Arctic. Macroalgal distribution was determined quantitatively by frame sampling and with digital video along transects at five hard-bottom locations from outer to inner fjord and interpreted against environmental gradients of depth (0–30 m), substratum, wave exposure and distance from inner glacial front. Most species identified (>70%) belonged to the Arctic and Arctic-temperate biogeographic groups, often with limited distribution to inner or outer part of the fjord. Dominant species or species with wide geographic distribution were typically widely distributed along the fjord axis. Peaks in biomass varied from 5 to 10 m at the middle-to-outer fjord, whereas in the inner bay it peaked at <5 m. The biomass distribution of macroalgae was mainly related to depth and distance from the inner glacial bay, and varied with wave exposure and sediment cover. Climate-related changes, after our study, indicate that the macroalgal belt has become shallower at Hansneset in middle fjord, with increased biomass in the upper sublittoral zone because of higher temperature and less sea ice. Distribution and production of macroalgae and fauna in shallow regions of the Arctic are likely to increase in the future, particularly in areas subjected to ocean warming, such as Kongsfjorden and other fjords and coastal areas in Svalbard.

MACROALGAE DIVERSITY IN CORAL REEFS AT THE WATERS OF TELUK TAMIANG VILLAGE, KOTABARU

The purpose of this study was to map the distribution of macroalgae at the waters of Teluk Tamiang Village, Kotabaru, South Kalimantan. The results showed that there were 8 species of macroalgae living in coral reef ecosystems. They originated from 7 order, 8 family, 8 genera, consisting of Acanthopora muscoides, Gracilaria coronopifolia, Amphiroa fragillissima Chlorodesmis sp., Halimeda macroloba, Enteromorpha sp., Turbinaria conoides, and Dictyota pinnatifida. The diversity index of two stations observed in this study was low.

Macrophytobenthos of the Caspian Sea: Diversity, distribution, and productivity

In the Russian sector of the northern and middle Caspian Sea, 36 species of macroalgae have been identified. The green and red algae from the mesosaprobic group are dominant. An increase in the number of green algae species is revealed. The distribution of macroalgae is inhomogeneous. It is confined to the solid substrate and epiphyton. The biomass of seaweeds reaches 1.5 kg/m2. Climate change has little influence on the appearance of new species in the northern Caspian Sea, but new invaders can appear in the Middle and Southern Caspian. The distribution of aquatic and coastal hygrophytic vegetation shows considerable spatial dynamics due to fluctuations in the level and salinity of the Caspian Sea. The biomass of aquatic vegetation varies in a wide range from 0.5 to 10.0 kg/m2. Spatially detailed mathematical models adequately reflect the changes in key species of aquatic plants in space and time. It is shown that expansion of the zone of the seagrass Zostera noltii to shallow water areas is occurring at present, as well as shrinkage of the range of the dominant littoral aquatic plant Phragmites australis.

The effects of sediment on Sargassum horneri in the early life stages on rocky subtidal reefs

Sediment plays an important role in controlling the distribution of macroalgae. We examined the distribution of Sargassum horneri in the field considering the effect of sedimentation, and conducted sediment manipulation experiments to test the hypothesis that sedimentation affects the early settlement stages of S. horneri. Field samplings were conducted on rocky subtidal platforms off Gouqi Island, in Zhoushan Archipelago in the Eastern China Sea. Water depth and motion were also measured. Sediment traps and a suction pump were used to collect in situ sediment. In the laboratory, two experiments were conducted to test the effects of sediment cover on zygote attachment and germling survival, respectively. Attachment rate of S. horneri zygotes was reduced from 81.3% of the control group to 3.6% with a medium dusting of sediment (approx. 0.5mm thickness), and 0% with a heavy dusting (approx. 0.7mm thickness). For the germlings, 1.0% of survived when covered by medium (approx. 0.7mm thickness) sediment coverage, whereas high coverage (approx. 1.8mm thickness) caused 100% mortality. Our study showed: 1) in the field, distribution of S. horneri was negatively correlated with sediment amount, and S. horneri was always found abundant in sites with less sediment and intermediate water motion; 2) in laboratory-based experiments, small changes in the abundance of deposited sediment prevented zygote settlement; and 3) relatively small increases in settling sediment affected the survival of already settled zygotes/germlings. In conclusion, we found that sediment was an important driver of S. horneri distribution, especially during the early settlement stages.

The influence of habitat structure, at different spatial scales, on the ecological distribution of macroalgal communities in streams

Habitat heterogeneity influences the composition and structure of macroalgal communities in lotic environments. However, depending on the spatial scale, different environmental characteristics may exert more or less influence. This study aimed to evaluate, at different spatial scales of observation, the influences of local and regional environmental variables on ecological distribution of macroalgae in stream ecosystems. The field work was conducted during the months of June and July 2007 in streams of two river basins located in southern Brazil. The spatial scales used were drainage basin, shading, mesohabitat, and microhabitat. According to the results, there are few differences regarding abiotic variables between spatial scales, however, suggesting that sunlight and, consequently, the shading scale have a strong impact on the distribution pattern of stream macroalgae. The mesohabitat scale at the current velocity proved to be an important factor in structuring communities of macroalgae. Finally, microenvironmental factors (e.g., substrate, current velocity, and light availability) appear to exert their direct influence on the spatial distribution of stream macroalgae, generating particular features in each spatial scale of observation, although regional abiotic parameters (e.g., temperature, pH, and conductivity) should also be considered for the structural characterization of these organisms.