Effects of stocking density on growth and skin color of juvenile darkbarbel catfish Pelteobagrus vachelli (Richardson)

A 3‐month experiment was conducted to investigate the effects of stocking density on growth performance and skin color of juvenile darkbarbel catfish. Experimental fish (5.0 ± 0.6 g; n = 160) were stocked in triplicate in 2 m² concrete tanks in a greenhouse at the initial density of 50, 150, 400 and 650 fish m^?2, respectively (0.42, 1.25, 3.33 and 5.42 kg m^?3). At the end of the experiment, 60 fish from each tank were sampled to record body weight and total length, and six fish from each tank were sampled to measure skin color by instrumental color analysis. Results showed that stocking density affected growth performance significantly (P < 0.05). Final mean weight (W), final mean total length (L) and specific growth rate (SGR) were significantly higher at 150 fish m^?2 treatment and lower in both the highest and lowest (650 and 50 fish m^?2) density treatments (P < 0.05). The condition factor (CF) was higher in 150 and 50 fish m^?2 and lowest at 650 fish m^?2 treatment; the coefficient of variation of weight (CV) tended to increase with the increase in stocking density, which was lowest in 50 fish m^?2 and highest in 650 fish m^?2. Stocking density also affected the skin color parameters, L* (lightness), a* (redness), b* (yellowness) and h* (hue), significantly (P < 0.05). The values of these parameters tended to decline with the increase in stocking density. Results of the present study suggest that growth performance and skin color responses to stock density exhibit different patterns for darkbarbel catfish juveniles: highest and lowest densities impaired growth rate, and higher density had a darkening effect on skin color.     

Effects of illumination and nitrogen starvation on accumulation of arachidonic acid by the microalga Parietochloris incisa

Parietochloris incisa is a unicellular freshwater green alga capable of accumulating high amounts of the valuable long-chain polyunsaturated arachidonic acid (AA) in triacylglycerols (TAG) of cytoplasmic oil bodies. To find the cultivation conditions providing maximum AA yield, the effects of illumination and N-availability on the dry weight (DW), chlorophyll, carotenoid, and AA content were studied. Under nitrogen starvation, TAG accounted for over 30% of dry weight (DW) and the AA content became as high as about 55% of total fatty acids. For biomass accumulation, light intensity of ca 400 μE m^?2 s^?1 was found to be optimal for growing P. incisa on a complete medium. Lower light intensities (or a higher cell density of inoculum) resulted in a higher AA yield when the alga was cultivated on nitrogen-free media. In the absence of nitrogen, algal cells were unable to cope with high illumination and suffered from photooxidative damage, whereas the nutrientsufficient culture survived under such illumination conditions, probably due to accumulation of carotenoids. Nitrogen-deprived P. incisa cells displayed elevated sensitivity to light.     

Changes in the population structure of Ascophyllum nodosum (L.) Le Jolis due to mechanical harvesting

The use of a Norwegian suction cutter to harvest populations of the brown alga Ascophyllum nodosum (L.) Le Jolis in southwestern Nova Scotia started in 1985. The impact of this type of mechanical harvest on the algal population structure was evaluated. Changes in the length and density of individual plants (clumps) within 0.25 m^–2 quadrats, as well as the length of individual shoots within clumps were monitored before and after an experimental harvest. The mechanical harvest cut mainly the longer plants, thus changed the initial bimodal size structure of the population to unimodal. There was a 20 to 36% plant mortality, reducing the plant density from 92.6 to 73.6 individuals m^–2. Pre-harvest size distribution of the tagged shoots was skewed to the right and became more normal after the harvest. Tagged shoots in the harvested quadrats suffered a 42% mortality as compared to 11% of those in the control quadrats. An understanding of the impact of the mechanical harvesting on the harvested population is essential in the design of a management strategy. Sources of variation in the impact of mechanical harvest include the tide level at time of harvest, length of time the machine operated in one site, skill of the machine operator, and sharpness of the machine cutting blades.     

Population dynamics of bacteria in Arctic sea ice

The dynamics of bacterial populations in annual sea ice were measured throughout the vernal bloom of ice algae near Resolute in the Canadian Arctic. The maximum concentration of bacteria was 6.0·10¹¹ cells·m^–2 (about 2.0·10¹⁰ cells·l^–1) and average cell volume was 0.473 m³ in the lower 4 cm of the ice sheet. On average, 37% of the bacteria were epiphytic and were most commonly attached (70%) to the dominant alga,Nitzschia frigida (58% of total algal numbers). Bacterial population dynamics appeared exponential, and specific growth rates were higher in the early season (0.058 day^–1), when algal biomass was increasing, than in the later season (0.0247 day^–1), when algal biomass was declining. The proportion of epiphytes and the average number of epiphytes per alga increased significantly (P<0.05) through the course of the algal bloom. The net production of bacteria was 67.1 mgC·m^–2 throughout the algal bloom period, of which 45.5 mgC·m^–2 occurred during the phase of declining algal biomass. Net algal production was 1942 mgC·m^–2. Sea ice bacteria (both arctic and antarctic) are more abundant than expected on the basis of relationships between bacterioplankton and chlorophyll concentrations in temperate waters, but ice bacteria biomass and net production are nonetheless small compared with the ice algal blooms that presumably support them.     

Experimental Studies on the Physiology of the Phycobiont and Mycobiont Ramalina ecklonii By

The lichenized fungus and alga of the fruticose lichen Ramalini ecklonii were isolated into pure cultures. The ascospores of the fungus failed to germinate in less than five weeks incubation in spite of the use of a variety of cultural conditions. The fungus showed a considerable increase in growth on malt extract agar. Both organisms showed a marked tolerance for high concentrations of glucose although growth was quantitatively reduced. The fungus was able to use a variety of carbon and nitrogen sources as well as an extract of algal cells. Cultivation in the absence of biotin and thiamine failed to yield significant amounts of growth. The alga yielded 27 mg of dry weight after three weeks in a synthetic medium under low light intensities. The alga could be grown in satisfactory amounts on CO₂ and inorganic salts with moderate light intensities. Experiments using ¹⁴CO₂ showed the fungus able to incorporate the extra-cellular and intra-cellular products of algal metabolism. The rate of incorporation of extra-cellular products was inhibited by high concentrations of biotin and thiamine. The alga assimilated ^l4CO₂ which was retained by the cells over a period of 14 days, at which time 78 per cent of the activity was insoluble in 80 per cent ethanol. An extract of the fungus labelled with ¹⁴C glucose was partially taken up by the alga and 50 per cent of the label was insoluble in 80 per cent after three days incubation in the light. No lichen acids were found in either the fungal cultures or the algal cultures although large amounts (e.g. 2 liters) of material were extracted and chromatographed. Usnic acid was produced by the intact lichen thallus.     

Light-dependent phagotrophy in the freshwater mixotrophic chrysophyte Dinobryon cylindricum

The mixotrophic (bacterivorous), freshwater chrysophyte Dinobryon cylindricum was cultured under a variety of light regimes and in bacterized and axenic cultures to investigate the role of phototrophy and phagotrophy for the growth of this alga. D. cylindricum was found to be an obligate phototroph. The alga was unable to survive in continuous darkness even when cultures were supplemented with high concentrations of bacteria, and bacterivory ceased in cultures placed in the dark for a period longer than one day. Axenic growth of the alga was poor even in an optimal light regime. Live bacteria were required for sustained, vigorous growth of the alga in the light. Carbon (C), nitrogen (N), and phosphorus (P) budgets determined for the alga during growth in bacterized cultures indicated that bacterial biomass ingested by the alga may have contributed up to 25% of the organic carbon budget of the alga. Photosynthesis was the source of most (75%) of the organic carbon of the alga. D. cylindricum populations survived but did not grow when cultured in a continuous low light intensity (30 E m^–2 sec^–1), or in a light intensity of 150 E m^–2 sec^–1 for only two hours each day. Net efficiency of incorporation of bacterial C, N, and P into algal biomass under these two conditions was zero (i.e., no net algal population growth). We conclude that the primary function of bacterivorous behavior in D. cylindricum may be to provide essential growth factor(s) or major nutrients for photosynthetic growth, or to allow for the survival of individuals during periods of very low light intensity or short photoperiod. Offprint requests to: David A. Caron     

Bacterial response to extracellular dissolved organic carbon released from healthy and senescent Fragilaria crotonensis (Bacillariophyceae) in experimental systems

Responses of bacteria to dissolved organic carbon (DOC) released from healthy and senescent Fragilaria crotonensis (Bacillariophyceae) were examined in experimental systems. The alga released DOC actively, although the concentration fluctuated greatly in both the axenic (the alga alone) and the mixed (the alga plus the enriched bacteria) cultures. In the control (the bacteria alone) cultures, both DOC concentration and bacterial density were low and almost constant throughout the experiment: 5.0 mg C 1^–1 and 1.1 × 10⁵ cells ml^–1, respectively. In the mixed cultures, bacterial growth was negligible during the exponential growth phase of the alga, but rapid proliferation of the bacteria occurred after the onset of the stationary growth phase. As the bacterial population grew, the density of senescent algal cells also increased. When the bacteria were fed on the DOC from healthy algae, their growth rate was relatively low (0.44 d^–1), but the maximum cell density was high (6.4 × 10⁵ cells ml^–1). Conversely, when the bacteria fed on the DOC of senescent algae, they grew at a relatively high rate (0.51 d^–1), but the maximum cell density was low (2.8 × 10⁵ cells ml^–1). These results suggest that DOCs released from dominant phytoplankton species in different physiological states affect the biomass and activity of bacteria.     

Do native herbivores provide resistance to Mediterranean marine bioinvasions? A seaweed example

Generalist herbivores in marine ecosystems are poorly examined for their potential to serve as a source of biotic resistance against algal invasion. We assessed how one of the main generalist herbivores in Mediterranean rocky reefs (the sea urchin Paracentrotus lividus) affects Lophocladia lallemandii and Caulerpa racemosa, two algal invaders with strong detrimental effects on native benthic communities. In a comparison of sea urchin gut contents to algal community composition, strong preferences were exhibited, leading to no relationship between consumption and availability. Both C. racemosa and L. lallemandi were abundant in algal assemblages (>60% occurrence), but C. racemosa (20% of diet) was consumed more than L. lallemandi (3.5%). Experimental enclosures of sea urchins (12 sea urchins * m⁻²) were carried out in locations where L. lallemandii was already established and C. racemosa was rare (new invasion) or abundant (established invasion). C. racemosa was negatively affected by sea urchins only when it was rare, and no effect was detected when the alga was already abundant. Results for L. lallemandi were exactly opposite: urchins limited seasonal increases in L. lallemandi in highly-invaded areas. Because of the small amount of direct consumption of L. lallemandi, its decrease in abundance may be related to the grazing of native algae where L. lallemandii is attached. Overall, our results show that high densities of native herbivores may reduce invasive algae at low densities, due to a combination of direct and indirect effects, but it has no significant effect in highly-invaded areas.     

Regulation of algal biomass in a small lowland stream: field experiments on the role of invertebrate grazing, phosphorus and irradiance

1. Field experiments were undertaken in a small Danish lowland stream to study the role of invertebrate grazing, phosphorus concentration and irradiance in the regulation of benthic algal biomass on stones. 2. Algal biomass was regulated by invertebrate grazing. The gastropod Ancylus fluviatilis prevented algal biomass build up in early spring at a density of about 900 ind. m^–2, and reduced algal biomass to very low levels during the algal growth period at a density of about 6000 ind. m^–2. Grazing pressure therefore might regulate the magnitude of peak algal biomass in Gelbæk stream, a finding in agreement with earlier field observations. 3. As phosphorus enrichment to around 152 μg l^–1 during the period when irradiance was not limiting did not result in any further increase in algal biomass, it can be concluded that algal growth in spring was not controlled by phosphorus limitation. 4. Algal biomass development differed significantly in a shaded and in a non-shaded reach of the stream. Only very low algal biomass accumulation was evident in the shaded reach, while in the non-shaded reach an algal biomass peak of about 800 mg chlorophyll m^–2 was evident after 6 weeks of colonization. The shaded reach represented the light condition in Gelbæk stream after leaf proliferation of the overhead canopy and high bank vegetation. The findings therefore suggest that irradiance available to the algal community after shading from riparian vegetation prevents further algal biomass increase and hence determines the timing of peak algal biomass in the stream. 5. The irradiance experiment also suggests that if not regulated by invertebrate grazing or shading by an overhead canopy in the summer, then the magnitude of peak biomass in Gelbæk stream will be regulated by self-shading in the algal community. 6. These field experiments support theories, derived from laboratory experiments and field studies, that regulation of algal biomass is a complex interaction of top-down and bottom-up mechanisms.     

An investigation of the relationship between sediment particles size and the development of green algal mats (Ulva prolifera) on the intertidal flats of Muan, Korea

The relationship between median grain size of sediments and the abundance in the wild of green algal mats (Ulva prolifera) on the intertidal flats of Muan, Korea, were investigated. The impact of substratum particle size on the growth and survival of germlings was examined in the laboratory. In the wild, the average annual density of algal mats was 7,950 ind m⁻². The algal mats mainly occurred in sands and exhibited patchy distribution. Statistical analysis indicates significant spatial analysis differences and a significant relationship between density and the ratio of sands to silts, suggesting that the distribution and density of this species were related to particle size. In laboratory experiments, the survival rate of U. prolifera germlings was the lowest value (22%) on sediments with a median grain size of 63–125 μm. Laboratory experiments have generally shown a positive relationship between attachment or survival of the alga and substratum particles size. Our laboratory results indicate a clear link between germling settlement/survival and substratum particle size. These results explain the spatial differences in abundance observed in the field in relation to the distribution and ratio of sands to silt on the Muan flats.     

Intracellular nitrite accumulation: The cause of growth inhibition of Microcystis aeruginosa exposure to high nitrite level

The aim of the present study is to test the role of intracellular nitrite in external nitrite suppressing algal growth. We examined the growth of Microcystis aeruginosa at different nitrite levels under high nitrate conditions and without nitrate conditions. There were higher intracellular nitrite and lower P_m^chla, R_d ^chla, α^chl, maximum cell density and specific growth rate in high nitrate group than nitrate absence group at 5 mg NO₂^?‐N L^?1. At 10 and 15 mg NO₂^?‐N L^?1, P_m^chla, R_d ^chla, α^chl, maximum cell densities and specific growth rates in the high nitrate group became higher than those of the nitrate absence group, while a lower intracellular nitrite in the high nitrate group than nitrate absence group was observed. In addition, the intracellular nitrite and the growth of M. aeruginosa in the high nitrate group did not change from 5 to 10 mg NO₂^?‐N L^?1. In the nitrite uptake experiment, with nitrite concentration increasing from 5 to 15 mg NO₂^?‐N L^?1, maximum nitrite uptake rate of alga increased, and half‐saturation constant of alga decreased. These results indicate that external nitrite inhibited algal growth through stimulating intracellular nitrite rise, which resulted from overexpression of nitrite transporter.     

Reduced digestibility of UV-B stressed and nutrient-limited algae by Daphnia magna

Daphnia magna was fed the green alga Selenastrum capricornutum, cultured under four different growth conditions: (1) phosphorus limitation, (2) nitrogen limitation, (3) UV-B irradiation, and (4) no nutrient limitation, no UV-B irradiation. Contrary to non-limited algal cells, nutrient-limited cells were not efficiently assimilated. Especially, P-limited cells passed through the gut mostly intact, while N-limited cells were partly assimilated. Also, algae exposed to moderate doses of UV-B radiation (0.3 mW cm^–2 of UV₃₁₂) were less efficiently assimilated after being grazed. Digestibility of the algae decreased with increased UV-B exposure time. Nutrient-limited and UV-B stressed algal cells increased in volume and became granular in appearance. These changes in the algal cells, combined with changed cell wall properties, most probably reduced their digestibility.     

The vertebrate pineal hormone melatonin is produced by the brown alga Pterygophora californica and mimics dark effects on growth rate in the light

Melatonin, a methoxylated indoleamine, plays a role as a mediator of darkness in animals as well as in the unicellular alga Gonyaulax polyedra Stein and was recently detected in higher plants. We report on the first finding of melatonin in a multicellular alga, the brown alga Pterygophora californica Rupr. Melatonin was identified in juvenile sporophytes of P. californica by two independent methods, reverse-phase high-performance liquid chromatography (HPLC) with electrochemical detection, and radioimmunoassay. Another indolic metabolite, 5-methoxytryptophol, was also indentified by HPLC. The rapid decline of growth rate upon the onset of darkness in P. californica is mimicked by melatonin in the light, with increasing efficiency from 5 × 10^–5M to 5 × 10^–4M, while no effect was obtained at 10^–5M.Abbreviations ANOVA analysis of variance - DMSO dimethyl sulfoxide - LD light-dark cycle K.L. and A.W. thank Petra Kadel for help with algal cultivation and evaluation of the experiments.     

Effects of grazing by Diadema antillarum Philippi (Echinodermata: Echinoidea) on algal diversity and community structure

In Discovery Bay, Jamaica W.I., densities of Diadema antillarum Philippi were experimentally manipulated over a range of 0–64 individuals · m^?2 with the aid of enclosures in shallow water. The effects of grazing by this echinoid on the algal community structure of a coral reef were compared under conditions of primary and post-primary succession.Algal biomass decreased as Diadema density was increased, particularly under primary succession conditions. A similar response was noted under post-primary conditions, but here biomass was also dependent on species composition and abundance of algae prior to experimental alterations of Diadema density. Peyssonnelia sp. was found to be particularly resistant to echinoid grazing, surviving even the most intense grazing. Within 11 months, algal diversity decreased significantly in an exponential fashion as Diadema density increased. This occurred under conditions of both primary and post-primary succession. Diversity, irrespective of index, was not maximized at intermediate grazing pressures. No single species of alga dominated the benthic community at even the lowest Diadema densities.Species composition of algae in the benthic community prior to changes in grazing pressure and lack of successful recruitment of a potential dominant were found to have a major influence on the response of the algal community to the treatments. Each of these factors can influence both the relationship between algal diversity and grazing pressure and the rate at which the community approaches an initial plateau of diversity in its earliest stages of succession.     

Effect of rearing density on pecking behaviour and plumage condition of laying hens in two types of aviary

The objective of this experiment was to investigate the effect of rearing density on pecking behaviour and plumage during rearing and throughout the laying period in aviaries. Chicks were reared on sand at high (H; 13 m⁻²) or low (L; 6.5 m⁻²) density, in four rearing pens of 390 chicks and eight pens of 195 chicks, respectively, each pen measuring 30 m². Proportions of chicks per pen performing various types of pecking behaviour were recorded by scan sampling during 16 observation bouts in each rearing pen at 6 weeks of age and during 24 observation bouts at 12 weeks. Individual body weights and plumage condition were recorded. Later, these pullets were housed at 17 hens m⁻² in Tiered Wire Floor (TWF; 3 H and 3 L pens of 275 hens) and Laco-Volétage (2 H and 2 L pens of 275 hens) aviaries. At 35 weeks, two samples of eight hens from each aviary pen were observed for pecking behaviour in a test pen. Throughout the laying period, additional records were collected on pecking behaviour, body weight, plumage condition, egg production, and mortality. The L birds had better plumage condition at 6 weeks of age and throughout the laying period. These birds also ground pecked more frequently than H birds during rearing and the laying period. At 12 weeks, L birds feather pecked less than H birds, but no relationship was found between rearing density and feather-pecking behaviour during the laying period. Although TWF hens feather pecked more frequently than Volétage hens, there was no interaction between rearing density and type of aviary for the various pecking behaviours.     

Comparative feeding ecology of two herbivorous damselfishes (Pomacentridae: Teleostei) from the Gulf of California,Mexico

Two species of benthic damselfishes from the Gulf of California, Mexico, use contrasting behaviors when feeding on benthic algal communities. The small (±70 g) Cortez damselfish, Eupomacentrus rectifraenum (Gill, 1862), feeds selectively from a multi-species algal mat, eats fleshy red and green algae and ignores brown and calcareous algae. The giant blue damselfish, Microspathodon dorsalis (Gill, 1862), is a large (±450 g), lethargic, nonselective feeder which grazes on a near monoculture of a fleshy red alga, Polysiphonia sp. Feeding activity for both species is low in the morning peaks during late afternoon, and drops sharply as night approaches. Based on feeding rates, gut-filling times, and weights of gut contents, Cortez damselfish process six to eight full guts of food and giant blue damselfish three full guts of food per day. The algal mat exhibits high standing crops (291–618 g dry wt · m^?2) and low productivity, but the preferred food of the Cortez damselfish (Ulva) appears to colonize the mat frequently and grow rapidly. The Polysiphonia dominated community on giant blue damselfish territories exhibits low standing crops (23 g · m^?2) and high productivity (34–47 times that of the mat per gram algae). Even though the feeding behaviors and resources used by the two damselfishes differ, both species eat similar food (delicate red and green fleshy algae, and depend on rapid colonization and/or high productivity to maintain their primary foods in the grazed algal community.     

Plant regeneration from mesophyll protoplasts ofDianthus superbus

Leaf mesophyll protoplasts ofDianthus superbus were cultured at a density of 5 × 10⁴ protoplasts/ml and divided at about 18% plating efficiency in MS liquid medium supplemented with 0.5 mg/L BAP, 2.0 mg/L NAA and 9% mannitol after 2 weeks. Protocolonies formed after 3 to 4 weeks of culture in the dark at 27°C. These colonies were transferred to continuous illumination (21.5 E m^–2 sec^–1) for 2 weeks where most of the colonies divided to form microcalli, about 2 mm in diameter. Subsequently, green microcalli were transferred to MS solidified medium with 2.0 mg/L 2,4-D that induced shoot-forming calli after 4 weeks. These calli were transferred onto N₆-2 medium containing 0.1 mg/L 2,4-D, 0.1 mg/L NAA, 2.0 mg/L kinetin and 2.0 g/L casein hydrolysate and were cultured under light. After 5 weeks the calli gave rise to multiple shoots (10 to 15 per callus). Upon transfer to MS medium containing 2.0 mg/L NAA, individual shoots were rooted in 4 weeks. The regenerants were successfully transplanted into potting soil.Abbreviations MS Murashige and Skoog - BAP 6-benzylaminopurine - 2,4-D 2,4-dichlorophenoxyacetic acid - NAA 1-naphthaleneacetic acid - N₆ Chu basal salt mixture - MES 2-N-morpholinoethanesulfonic acid     

Optimizing performance of a microbial carbon-capture cell using Box-Behnken design

Performance of a microbial carbon-capture cell (MCC), in which a microbial fuel cell and a photo-bioreactor gets mutually benefitted, is reliant on certain critical factors. In present investigation, Box-Behnken design is adopted to statistically evaluate the effect of influential parameters, namely nitrate concentration in catholyte, photoperiod and concentration of lipid extracted algae (LEA) of mixed culture microalgae in the anodic inoculum, on the performance of MCC. As per validation experiment, based on statistical model prediction, the ideal performance (higher power density and algal productivity) was achieved at LEA concentration, nitrate concentration and photoperiod in a range of 5.3–5.7 g/L, 44−50 mg/L and 10.00–10.67 h, respectively. Furthermore, the accuracy of model predictions was successfully validated by operating a separate MCC, which gave a power density and algal productivity (7.12 ± 0.09 W/m³ and 0.83 ± 0.02 g/L.day) close to the predicted output (7.05 ± 0.13 W/m³ and 0.838 ± 0.019 g/L.day). Box-Behnken design aided in optimizing the influential factors so as to make MCC economical and efficient for scale-up.     

The Role of Glycerol in the Osmotic Regulation of the Halophilic Alga Dunaliella parva

Dunaliella parva, a green halophilic alga, was found to accumulate very large amounts of intracellular glycerol. Through measurements of the intracellular volume the internal concentration of glycerol was calculated and found to be around 2.1 m in cells cultured in 1.5 m NaCl. When the extracellular salt concentration of an algal suspension was increased or decreased, the intracellular glycerol varied accordingly, reaching its new osmotic equilibrium after about 90 minutes. Since no leakage of intracellular glycerol was observed above 0.6 m NaCl, these alterations in glycerol content are interpreted as due to metabolic formation and degradation of intracellular glycerol. The above results indicate the existence of a new type of algal osmoregulation, in which the osmotic balance depends on the synthesis or degradation of intracellular glycerol in response to the external salt concentration.     

Epifauna living on sublittoral seaweeds around Cyprus

Macroepifauna living on sublittoral seaweeds were counted,identified and compared among six locations in Cyprus. Mollusks,amphipods, and polychaetes were the major taxa represented. Thedominant alga was Cystoseira barbata which was present at 4of 6 stations and ranged in wet weight from 1–2 kg m^-2 ofbottom. Percent cover of C. barbata ranged from 25 to 90%.Other dominant algae were Laurencia obtusa, Padinapavonica, and Jania rubens. The distribution of epifaunaabundance, species composition, and species richness varied amonglocations. Total epifauna abundance ranged from 1000 to 2250animals m^-2. The abundance of epifauna per gram of plant wassignificantly lower on C. barbata than on the other algalspecies. The total epifauna species richness was more related tolocal algal plant diversity than to plant biomass.