Acanthophora Spicifera Research Articles

Synthesis of Bioethanol by Dark Fermentation Using Marine Seaweed Acanthophora spicifera (Vahl.) Borgesen as a Cheap Substrate

The Indian subcontinent constitutes about 7516.6 km of Coastal cover on the three borders and thus rich in marine biodiversity. More than 200 species of seaweeds have been reported to exist in this region attached to the surface of the rocks. Many seaweed based industries have been laid in these coastal zones and they utilize seaweed as raw materials for the production of agar and alginate. Several research studies reveal that the seaweed biomasses are rich in simple and complex sugars and can be utilized as a cost effective substrate for the commercial production of bioethanol. In many parts of the world the commercial exploitation and evaluation of bioethanol production from seaweeds are being practiced. However, India is rich in marine bio resources for the cultivation of seaweeds and can be directly utilized for the biochemical conversion of sugars into bioethanol. The present research study is an initial step for the commercial exploitation of marine seaweed Acanthophora spicifera (Vahl.) Borgesen for the bioethanol production. In which, the bioethanol synthesis was analyzed between both the raw substrate (Powdered seaweed biomass) and raw substrate with banana fruit supplement. The accumulation of bioethanol was almost similar in both the substrate when growing baker’s yeast. And from the results, it has been revealed that approximately 6 % of bioethanol yield was obtained from the raw seaweed substrate. Therefore, this present small scale pilot study hugely supports the commercial exploitation of marine seaweeds for the bioethanol production.

Impact of Submarine Groundwater Discharge on Marine Water Quality and Reef Biota of Maui

Generally unseen and infrequently measured, submarine groundwater discharge (SGD) can transport potentially large loads of nutrients and other land-based contaminants to coastal ecosystems. To examine this linkage we employed algal bioassays, benthic community analysis, and geochemical methods to examine water quality and community parameters of nearshore reefs adjacent to a variety of potential, land-based nutrient sources on Maui. Three common reef algae, Acanthophora spicifera, Hypnea musciformis, and Ulva spp. were collected and/or deployed at six locations with SGD. Algal tissue nitrogen (N) parameters (δ15N, N %, and C:N) were compared with nutrient and δ15N-nitrate values of coastal groundwater and nearshore surface water at all locations. Benthic community composition was estimated for ten 10-m transects per location. Reefs adjacent to sugarcane farms had the greatest abundance of macroalgae, low species diversity, and the highest concentrations of N in algal tissues, coastal groundwater, and marine surface waters compared to locations with low anthropogenic impact. Based on δ15N values of algal tissues, we estimate ca. 0.31 km2 of Kahului Bay is impacted by effluent injected underground at the Kahului Wastewater Reclamation Facility (WRF); this region is barren of corals and almost entirely dominated by colonial zoanthids. Significant correlations among parameters of algal tissue N with adjacent surface and coastal groundwater N indicate that these bioassays provided a useful measure of nutrient source and loading. A conceptual model that uses Ulva spp. tissue δ15N and N % to identify potential N source(s) and relative N loading is proposed for Hawaiʻi. These results indicate that SGD can be a significant transport pathway for land-based nutrients with important biogeochemical and ecological implications in tropical, oceanic islands.

Quantification and Correlation Study on Derived Phenols and Antioxidant Activity of Seaweeds from Gulf of Mannar

ABSTRACTSelected seaweeds (Acanthophora spicifera, Gracilaria edulis, Padina gymnospora, Ulva fasciata, and Enteromorpha flexuosa) from the Gulf of Mannar coast, India, were analyzed for their antioxidant properties. Derived phenols in the methanolic extracts of these seaweeds were quantified and their scavenging activity against 1,1-diphenyl-2-picrylhydrazyl (DPPH) and nitric oxide were examined. Total phenol content was the highest in U. fasciata (23 mg TAE.g–1) and the lowest in A. spicifera (8.8 mg TAE.g–1). Caffeic acid ranged from 0.02 to 1.30 mg.100 g–1 and gallic acid ranged from 0.02 to 1.2 mg.100 g–1. Other derived phenols, coumeric acid, apigenin, chlorogenic acid, 3,4-dihydroxy benzoic acid, and qucercetin, were found in all species. U. fasciata showed the highest efficiency (11 µg.mL–1) against DPPH activity, while E. flexuosa (42 µg.mL–1) had the lowest low activity. G. edulis (36.3%) proved more potent in nitric oxide scavenging activity than any other species, and the lowest activity was noted in E. flexuosa (12.2%). There was a positive correlation between chlorogenic and gallic acids and radical scavenging activity.

English

First generation drugs such as zidovudine have been extensively used in clinical practice, resulting in the development of HIV resistance to these nucleoside analogs. Several studies have demonstrated the effective anti-HIV activity of natural products derived from seaweeds, suggesting promising sources of substances for the development of novel antiviral drugs. In this paper, the antiviral effect of extracts from the red seaweed Acanthophora spicifera on HIV-1 replication was evaluated in vitro. Peripheral blood mononuclear cells obtained using the Ficoll-Hypaque gradient were used for cytotoxicity and antiviral activity testing. The dichloromethane extracts, ethyl acetate, acetone, and methanol were found to have CC50 values of 31±7.4, 45±11, 38±3.5, and 179±25 µg/mL, respectively. With the control, the extract prepared in ethyl acetate inhibited approximately 60% of the viral load, which is the best result among the extracts. This same extract showed an IC50 value of 33.17±4.84 μg/mL for the reverse transcriptase. The EtOAc extract from A. spicifera showed to be an efficient HIV antiviral due to its phenolic compounds, as evaluated by nuclear magnetic resonance. Key words: Marine natural products, red seaweed, Acanthophora spicifera, HIV-1, Antiviral activity, Anti-HIV-1 RT.

Assessing the herbivore role of the sea-urchin Echinometra viridis: Keys to determine the structure of communities in disturbed coral reefs

Echinometra viridis previously was considered a cryptic species unable to control the development and growth of macroalgae on coral reefs. Its role as a herbivore was seen as minor compared to other grazers present on the reef. However, the present disturbed state of some reefs has highlighted the role played by this sea-urchin. Combining field data with experiments on the Caribbean coast of Panama, we demonstrate that the current community organization on disturbed coral reefs in the Mesoamerican Caribbean is largely due to the action of E. viridis. It is the most abundant sea-urchin species, together with two others (Diadema antillarum and Echinometra lucunter). Field data also indicate that the relationship between its density and the abundance of macroalgae is stronger and it is more negative in impact than those of the other two. However, the niche this urchin exploits most efficiently is confined to leeward reefs with low levels of sedimentation. Outside these habitats, their populations are not decisive in controlling macroalgal growth. Grazing experiments showed that E. viridis consumes more fresh macroalgae per day and per weight of sea-urchin, and is a more effective grazer than D. antillarum or E. lucunter. E. viridis showed food preferences for early-successional turf macroalgae (Acanthophora spicifera), avoiding the less palatable late-successional and fleshy macroalgae (Lobophora variegata, Halimeda opuntia). However, it becomes a generalist herbivore feeding on all varieties of macroalgae when resources are scarce. H. opuntia is the macroalga that most resists E. viridis activity, which may explain its wide distribution.

The protective effect of dietary flavonoid fraction from Acanthophora spicifera on streptozotocin induced oxidative stress in diabetic rats

The present investigation was considered in arraying of antidiabetic and antioxidant activity from dietary flavonoid loaded fraction of Acanthophora spicifera (A. spicifera, Family: Rhodomelaceae) on streptozotocin (STZ) induced oxidative stress rats. The testings were acted upon male rats, which were alienated into five groups: control group, diabetic group (single dose of 65mg/kg, streptozotocin (STZ) i.p.), diabetic with insulin (6IU), and diabetic with flavonoid rich fraction groups (FRF) at 50 and 100mg/kg body weight, given orally for 21 days. The blood glucose level was determined at different week intermissions. The antioxidant consequences of FRF on STZ-induced diabetic rats were determined by the estimations of the oxidative stress marker like malonyldialdehyde and antioxidant enzymes such as superoxide dismutase, catalase and glutathione in tissue homogenates of heart, liver and kidney. FRF treatment of diabetic rats significantly (P<0.05) diminishes the blood glucose altitudes to normal in contrast with diabetic rats. However, FRF administration, significantly decreased the malonyldialdehyde (MDA) and increased the activities of superoxide dismutase (SOD), catalase (CAT) and glutathione levels (GSH) in diabetic rats. The outcome designates that FRF fraction from red algae A. spicifera was potent anti diabetic and antioxidant asset against STZ induced diabetes and oxidative tissue breakups.

Isolation and Identification of a Flavone Apigenin from Marine Red Alga Acanthophora spicifera with Antinociceptive and Anti-Inflammatory Activities.

Physicochemical investigation of the red alga Acanthophora spicifera (Vahl) Borgesen, collected from Al-Shoaiba coast, Red Sea, Saudi Arabia, led to the isolation of a flavone from the algal tissue with acetone. Preparative chromatography on silica gel thin-layer chromatography was used for the separation of the flavone and eluted with the methanol:chloroform:ethyl acetate (1:7:2) solvent system. The physicochemical analyses infrared, mass spectra, and ultraviolet spectra in addition to shift reagents (NaOMe, NaOAc, NaOAc + H3BO3, AlCl3, and AlCl3 + HCl) were used for the identification and elucidation of the structure of the flavone compound (4,5,7-trihydroxy flavonoids). The flavone compound was identified as apigenin bycomparing its physicochemical data with those in the literature. Analgesic and anti-inflammatory activities of apigenin were evaluated. Apigenin showed promising analgesic and anti-inflammatory activities in the hot plate test and writhing test in mice as well as tail-immersion tests and carrageenan-induced paw edema and cotton pellet-induced granuloma formation in rats. It is concluded that apigenin possesses potent analgesic, anti-inflammatory, and antiproliferative activities, which might be due to the inhibition of PGE2 as well as proinflammatory cytokines such as interleukin-1β, interleukin-6, and tumor necrosis factor-α.

Survivorship and feeding preferences among size classes of outplanted sea urchins, Tripneustes gratilla, and possible use as biocontrol for invasive alien algae.

We investigate the survivorship, growth and diet preferences of hatchery-raised juvenile urchins, Tripneustes gratilla, to evaluate the efficacy of their use as biocontrol agents in the efforts to reduce alien invasive algae. In flow-through tanks, we measured urchin growth rates, feeding rates and feeding preferences among diets of the most common invasive algae found in Kāneʻohe Bay, Hawaiʻi: Acanthophora spicifera, Gracilaria salicornia, Eucheuma denticulatum and Kappaphycus clade B. Post-transport survivorship of outplanted urchins was measured in paired open and closed cages in three different reef environments (lagoon, reef flat and reef slope) for a month. Survivorship in closed cages was highest on the reef flat (∼75%), and intermediate in the lagoon and reef slope (∼50%). In contrast, open cages showed similar survivorship on the reef flat and in the lagoon, but only 20% of juvenile urchins survived in open cages placed on the reef slope. Urchins grew significantly faster on diets of G. salicornia (1.58 mm/week ± 0.14 SE) and Kappaphycus clade B (1.69 ± 0.14 mm/wk) than on E. denticulatum (0.97 ± 0.14 mm/wk), with intermediate growth when fed on A. spicifera (1.23 ± 0.11 mm/wk). Interestingly, urchins display size-specific feeding preferences. In non-choice feeding trials, small urchins (17.5–22.5 mm test diameter) consumed G. salicornia fastest (6.08 g/day ± 0.19 SE), with A. spicifera (4.25 ± 0.02 g/day) and Kappaphycus clade B (3.83 ± 0.02 g/day) intermediate, and E. denticulatum was clearly the least consumed (2.32 ± 0.37 g/day). Medium-sized (29.8–43.8 mm) urchins likewise preferentially consumed G. salicornia (12.60 ± 0.08 g/day), with less clear differences among the other species in which E. denticulatum was still consumed least (9.35 ± 0.90 g/day). In contrast, large urchins (45.0–65.0 mm) showed no significant preferences among the different algae species at all (12.43–15.24 g/day). Overall consumption rates in non-choice trials were roughly equal to those in the choice trials, but differences among feeding rates on each species were not predictive of feeding preferences when urchins were presented all four species simultaneously. In the choice feeding trials, both small and medium urchins clearly preferred A. spicifera over all other algae (roughly twice as much consumed as any other species). Again, however, differences were less pronounced among adult urchins, with adults showing a significant preference for A. spicifera and Kappaphycus clade B compared to the other two algal species. These findings indicate that outplanted urchins are surviving on the reef flats and eating a variety of alien invasive algae as intended. Although juvenile urchins show stronger feeding preferences, these animals grow quickly, and adult urchins are more generalist herbivores that consume all four alien invasive algae.

Increased use of non-native algae species in the diet of the Green Turtle (Chelonia mydas) in a primary pasture ecosystem in Hawaii

The Green Turtle, Chelonia mydas, has modified its feeding behavior over the past 36 years to include the increasing abundance of non-native algae growing in the greater Kaneohe Bay area of Oahu, Hawaii. Changes in diet of the Turtles are correlated with an increase in abundance of non-native algae. Turtles are eating 135 species of marine vegetation including the following seven non-native species: Acanthophora spicifera, Hypnea musciformis, Gracilaria salicornia, Eucheuma denticulatum, Gracilaria tikvahiae, Kappaphycus striatum and Kappaphycus alvarezii. Non-native algae now represent 0.64 proportion of the Turtle diet. The present study for the additional 8 years 2005–2012, shows the utilization of non-native species for food has increased 24% since the last study that included 28 years 1976–2005. Average time for the Turtles to make the shift to non-native species is 10–12 years for the more invasive species and 20–30 years for the slower growing species. During this same time period the numbers of C. mydas, body size, and growth rates have also increased, partly due to the increased abundance of the additional non-native food items. This study verifies that the trend of Turtles eating higher amounts of non-native algae in Kaneohe Bay is now stronger than first reported in 2009.

Among-habitat algal selectivity by browsing herbivores on an inshore coral reef

Understanding how the impact of different herbivores varies spatially on coral reefs is important in qualifying the resistance of coral reefs to disturbance events and identifying the processes that structure algal communities. We used assays of six common macroalgae (Acanthophora spicifera, Caulerpa taxifolia, Galaxaura rugosa, Laurencia sp. Sargassum sp., and Turbinaria ornata) and remote underwater video cameras to quantify herbivory in two habitats (reef crest and slope) across multiple sites on Orpheus Island, Great Barrier Reef. Rates of herbivory varied among macroalgal taxa, habitats, and sites. Reductions in algal biomass were greatest for Sargassum sp. (36 % 4 h−1), intermediate for A. spicifera, Laurencia sp., C. taxifolia, and T. ornata (17–33 % 4 h−1) and lowest for G. rugosa (6 % 4 h−1). Overall, rates of herbivory were generally greater on the reef crest (30 % 4 h−1) than the reef slope (21 % 4 h−1). This difference in rates of herbivory coincided with a marked shift in the dominant herbivores between habitats. Kyphosus vaigiensis, despite only feeding on three species of macroalgae (Sargassum sp., T. ornata, and A. spicifera), was responsible for 34 % of all bites recorded on the reef crest yet did not take a single bite from algae on the reef slope. In contrast, Siganus doliatus took bites on every species of algae in both habitats, accounting for 40 % of bites on the reef crest and 74 % of all bites recorded on the reef slope. This difference in the number of macroalgal species targeted by herbivores and the habitat/s in which they feed adds another dimension of complexity to our understanding of coral reef herbivore dynamics.

Antifouling potential of the selected macroalgae from the gulf of Mannar, India

Marine macroalgae are mostly free from fouling organisms in the marine environment. They defend themselves against fouling directly through the production of antifouling compounds, or indirectly through regulating the attachment of micro and macrofoulers. In this study, the methanolic extracts of 43 species of macroalgae, collected from the Gulf of Mannar and Palk Bay regions of India, were evaluated for antifouling activity against the epiphytic diatoms ( Navicula subinflata , Nitzschia palea ) as well as cyprid larvae of Balanus amphitrite . It was found that extracts of 23 species of macroalgae exhibited antidiatom activity and 16 extracts inhibited settlement property of barnacle larvae. The algae, Asparagopsis taxiformis showed the highest inhibitory effect on both the test diatoms with inhibition of 11.5±1.11 mm and 14.25±2.38 mm zones respectively. Meanwhile, Liagora erecta and Acanthophora spicifera exhibited highest activity against the diatom, Navicula subinflata . The assay using cyprid larvae revealed that 16 algal extracts showed antisettlement activity and the highest was recorded by Liagora erecta (84.80±1.33% inhibition), with an IC 50 of 77.45 μg ml -1 . The observations in the present study revealed that ten species of macroalgae have both micro and macrofouling property. The Principal Component Analyses (PCA) was also employed to assess the antifouling activity of algae.

Dual roles of an algal farming damselfish as a cultivator and opportunistic browser of an invasive seaweed.

Herbivory is a fundamental process determining reef resilience, and while algal farming damselfishes can help shape benthic assemblages, an understanding of their contribution to areas outside of defended territories is relatively unexplored. Here, we demonstrate how the farming damselfish Stegastes marginatus plays a dual role in benthic structuring by 1) contributing to persistence of the invasive macroalga Acanthophora spicifera within a Hawaiian marine protected area, where the macroalga occurred exclusively inside Stegastes territories, and 2) behaving as an opportunistic browser of the exotic alga outside their territorial borders. Greater than 50% of the biomass of tethered A. spicifera was consumed within one-hour when placed outside Stegastes territories, compared to <5% lost from tethers within territories or herbivore exclusion cages. In situ remote video revealed that tethered A. spicifera located outside territories was grazed primarily by the surgeonfish Acanthurus nigrofuscus (∼68% of total bites) and, surprisingly, by S. marginatus (∼27% of total bites) that left their territories to feed on this resource on 107 occasions during 400 min of filming. Further, for over half of those occurrences where S. marginatus grazed on the tethered macroalga outside of territories, they fed alongside conspecifics and other species, displaying little of the aggressiveness that characterizes this damselfish. These results show that S. marginatus plays a wider role in determining benthic assemblages than previously recognized, acting both as cultivators of a canopy-forming invasive macroalga within their territories, and as opportunistic browsers in neighboring sites. Consequently, S. marginatus can affect benthic species composition across their territory borders. These results provide a rare example of interspecific facilitation of an exotic alga by an indigenous marine fish. Accounting for fish behaviors more broadly is important to further our understanding of ecological processes that shape reef ecosystems to improve management of MPAs that often support extensive farming damselfish populations.

Cadmium and copper toxicity in three marine macroalgae: evaluation of the biochemical responses and DNA damage.

Marine macroalgae have evolved a different mechanism to maintain physiological concentrations of essential metal ions and non-essential metals. The objective of the present work was to evaluate the antioxidant response and DNA damage of copper and cadmium ions in three halophytes, namely, Acanthophora spicifera, Chaetomorpha antennina, and Ulva reticulata. Accumulation of copper was significantly higher (P < 0.05) than that of cadmium. Biochemical responses showed that copper was considerably more toxic than cadmium (P < 0.05). Decreases in glutathione content and fluctuations of super oxide dismutase, catalase, and glutathione peroxidase activities were observed corresponding to time and concentration of exposure. Interestingly, it was also observed that antioxidant levels decreased as a result of metal accumulation, which may be due to free radicals generated by copper and cadmium in seaweeds. The present study also showed that copper and cadmium increased oxidative stress and induced antioxidant defense systems against reactive oxygen species. The order of toxicity for metals in the studied seaweeds was U. reticulata > A. spicifera > C. antennina. DNA damage index analysis supported that copper was significantly (P < 0.05) more toxic than cadmium. Bioaccumulation, biochemical responses, and DNA damage observed in the here analyzed marine macroalgae after exposure to selected metals indicate that these marine organisms represent useful bioindicators of marine pollution.

Seasonal variation of economic seaweed at Bai No, Ha Tien, Kien Giang province

The total 23 economic species belong to 14 genus of 10 family were recorded by 4 field trips during the wet and dry seasons of the year 2011 and 2012 at Bai No zone, Ha Tien district, Kien Giang province. Among species collected at the area, 11, 9 and 3 species were recorded for Chlorophyta, Rhodophyta and Heterokontophyta (Phaeophyceae), respectively. The number of species recorded for both dry and wet seasons was up to 9 species (est. 39% of total), in which, 7 species present at whole the field trips. Diversity of economic seaweed in the wet season was more dominentaly than that of the dry season: 16 species recorded for 13 genuses of 9 families in wet seanson comparing to 18 species recorded for 11 genuses of 8 families in dry season. Species Gracilaria rubra was the main seaweed biomass of this area. Some of Agarophytes species were also recorded for the area such as Hydropuntia fisheri, Gracilaria salicornia, Hydropuntia changii, and Acanthophora spicifera. Of Carrageenophytes species unidentified species of the genus Hypnea was recorded.

Epiphytic dinoflagellates associated with ciguatera in the northwestern coast of Cuba

The spatial and temporal abundance of epiphytic dinoflagellates associated with ciguatera was studied over two annual cycles (March 1999 to March 2000 and March 2001 to March 2002) in the northwestern coast of Cuba. From 14 species of macroalgae (Phaeophyta, Chlorophyta, and Rhodophyta), 1340 samples were obtained identifying seven species as potentially noxious; five of them are new reports for Cuba's phytobenthos: Prorocentrum belizeanum Faust, P. concavum Fukuyo, P. mexicanum Tafall, Coolia monotis Meunier, and Ostreopsis lenticularis Fukuyo. ANOVA/MANOVA analysis showed significant spatial differences: lower cell abundance near the shoreline adjacent to a river inlet and higher cell abundance in the deepest area. Prorocentrum lima (Ehrenberg) Dodge 1975 was found mainly on Phaeophyta followed by Chlorophyta and Rhodophyta. Gambierdiscus toxicus was found mainly on Phaeophyta followed by Rhodophyta and Chlorophyta. All the species reported in the study area were mainly on Padina spp. (Phaeophyta). Acanthophora spicifera (Rhodophyta) did not host dinoflagellate species. Environmental conditions in summer (higher temperature, more nutrients, greater water transparency, and low wind intensity) are suitable for macroalgae development, which serves as a substrate for potentially harmful dinoflagellates, and possibly the main vector for spreading ciguatera along the coast of Cuba.

Lifespan extension of rotifers by treatment with red algal extracts

Aging results from an accumulation of damage to macromolecules inhibiting cellular replication, repair, and other necessary functions. Damage may be due to environmental stressors such as metal toxicity, oxidative stress caused by imperfections in electron transfer reactions, or other metabolic processes. In an effort to discover medical treatments that counteract this damage, we initiated a search for small molecule drugs from natural sources using life table experiments which, through their unbiased approach, present the opportunity to discover first-in-class molecules. We have identified marine red algae as a source of natural products that slow aging of the invertebrate rotifer Brachionus manjavacas. Rotifers are a promising model organism for life extension studies as they maintain a short, measurable lifespan while also having an extensive literature related to aging. Rotifer lifespan was increased 9–14% by exposure to three of a total of 200 screened red algal extracts. Bioassay guided fractionation led to semi-purified extracts composed primarily of lipids responsible for rotifer life extension. The life extending mixture from the red alga Acanthophora spicifera contained eicosanoic, octadecanoic, and hexadecanoic acids as well as several unidentified unsaturated fatty acids. The life extending effects of these small molecule mixtures are not a result of their direct antioxidant capacity; other unknown mechanisms of action are likely involved. An understanding of how these natural products interact with their molecular targets could lead to selective and effective treatments for slowing aging and reducing age related diseases.

Can stormwater be detected by algae in an urban reef in Hawai‘i?

Nitrogen (N) enrichment of tropical reefs can result in the dominance of invasive algae. The invasive alga Acanthophora spicifera and the native alga Laurencia nidifica are part of a diverse reef assemblage in ‘Ewa Beach, O‘ahu. Their N contents and δ15N values were investigated to determine if N was enriched and to evaluate potential nitrogenous sources near and removed from storm-drain outlets. δ15N values of algae (3.8–17.7‰) were within and above the range for algae around the island (1.9–11.9‰). Elevated algae N isotope values (δ15N>+7‰, [N]>1.6%) and seawater nitrate+nitrite levels (0.59–7.93μM) indicated a mixed, high nutrient environment. The overlap in δ15N values with multiple nitrogenous sources precluded identification. However, spatial and temporal patterns did not support stormwater as the dominant, nitrogenous source. Patterns were congruent with algal incorporation of terrestrial derived N, subjected to a high degree of biogeochemical cycling.

The effects of storm-drains with periodic flows on intertidal algal assemblages in ‘Ewa Beach (O‘ahu), Hawai‘i

Storm-water drainage systems have potential to collect and focus nutrient enriched runoff into coastal systems. Storm-drain effluent could support macroalgal production and result in altered communities. To test this hypothesis, we assessed species composition and percent cover of native and non-native benthic macroalgae at eight intertidal sites along ‘Ewa Beach, Hawai‘i. Three sites contain storm-drainage outlets (drain 16–52acres) that deliver effluent into the intertidal zone whereas five sites were located⩾100m away and served as comparisons to determine differences related to the presence of storm-water. Results revealed lush and diverse macroalgal assemblages, similar at all sites. Furthermore, the abundance of non-native species (Acanthophora spicifera, Hypnea musciformis) was not related to presence of storm-drains. The finding that macroalgal assemblages are not related to storm-waters is contrary to an earlier investigation in the same location and underscores the importance of sampling design and habitat variation when assessing impacts.

Spatial and Temporal Variation in Rocky Intertidal Communities Along the Main Hawaiian Islands

Thirteen benthic rocky intertidal communities were quantitatively assessed on Maui, Moloka'i, O'ahu, and Hawai'i Island between the years 2004 and 2007. Our goals were to test for differences in invertebrate and macroalgal abundance and composition to understand how these tropical communities are organized. Percentage cover surveys revealed a diverse intertidal system with 49 macroalgal, 1 cyanobacterial, and 31 invertebrate taxa. Shores were frequently dominated by a few macroalgae and mollusks, and at two sites these organisms were distributed in discrete vertical bands. Common intertidal taxa included the introduced alga Acanthophora spicifera; species in the macroalgal genera Padina, Sargassum, and Laurencia; turf forms of algae; and the mollusks Siphonaria normalis, Nerita picea, and species of littorine snails. Multivariate statistics found community structure to vary among sites and years, but there was lack of evidence for island-specific or substratum-specific assemblages. SIMPROF analysis revealed support for 11 different types of structure. This first description of community-level patterns at multiple intertidal sites along the Main Hawaiian Islands documents substantial spatial variation both among and within shores, as well as substantial temporal variation for select sites. These findings are in contrast to the characterization of a homogeneous tropical system and thus suggest that biotic and abiotic factors in the Main Hawaiian Islands act on a local scale to drive structure.

Nutrient addition increases consumption rates of tropical algae with different initial palatabilities

While nutrient enrichment increases herbivory rates on highly palatable species of tropical algae, it is unclear how nutrient enrichment affects species with differing initial palatabil- ities. We determined that there was a wide range in relative palatability among 5 perennial and common species of Caribbean coral reef algae in a cafeteria-style choice experiment, with overall preference for Acanthophora spicifera the highest, Dictyota dichotoma and Caulerpa sertulari- oides intermediate, and Turbinaria turbinata and Sargassum polyceratium the lowest, although there were significant differences in grazing rates among algal species between the 2 fringing reef sites tested. We then tested the hypothesis that increased nutrient content in algae increases palatability using choice experiments between enriched and ambient algal samples for each of 3 species along this palatability gradient: A. spicifera, D. dichotoma, and S. polyceratium. For all species, herbivores selected enriched over ambient samples across the 2 sites despite contrasting herbivore guilds (i.e. dominated by sea urchin Diadema antillarum versus herbivorous fishes). However, despite increased palatability of enriched S. polyceratium, overall herbivory on this spe- cies was still relatively low compared to other studies, suggesting that S. polyceratium in this sys- tem may have stronger chemical defenses, or that a specialist herbivore guild may be missing on this Caribbean reef. Regardless of the mechanism, our study implies that anthropogenic or natural events that result in high supplies of nutrients in coral reef seawater will increase overall seaweed palatability, even of unpalatable species.