Epiphyte Biomass Research Articles

Nutrient induced changes in the species composition of epiphytes on Cladophora glomerata Kütz. (Chlorophyta)

Cladophora glomerata is a widely distributed filamentous freshwater alga that hosts a complex microalgal epiphyte assemblage. We manipulated nutrients and epiphyte abundances to access their effects on epiphyte biomass, epiphyte species composition, and C. glomerata growth. C. glomerata did not grow in response to these manipulations. Similarly, nutrient and epiphyte removal treatments did not alter epiphyte biovolume. Epiphyte species composition, however, changed dramatically with nutrient enrichment. The epiphyte assemblage on unenriched C. glomerata was dominated by Epithemia sorex and Epithemia adnata, whereas the assemblage on enriched C. glomerata was dominated by Achnanthidium minutissimum, Nitzschia palea and Synedra spp. These results indicate that nutrients strongly structure epiphyte species composition. Interactions between C. glomerata and its epiphytes were not affected by epiphyte species composition in our experiment but may be when C. glomerata is actively growing.

An experimental test of the mechanism by which suspension feeding bivalves elevate seagrass productivity

A field experiment utilizing mussel mimics and sediment nutrient enrichment was con- ducted to examine the effect of the mussel Modilous americanus on meadows of the seagrass Tha- lassia testudinum. The experimental design tested the separate factors of increased habitat structure and increased nutrient enrichment resulting from the presence of the mussels. Nutrient enrichment had a significantly positive effect on sediment porewater nutrient concentrations and a significantly negative effect on leaf tissue C:N, C:P and N:P ratios. Increased habitat structure had a significantly positive effect on epiphytic grazer densities and a significantly negative effect on epiphytic biomass. In addition, calculated % light reduction by epiphytes was significantly reduced by structure and significantly increased by nutrient enrichment. This study showed that the direct effect of nutrient enrichment by mussel biodeposition produced the greatest positive response in productivity of T. testudinum in the seagrass meadows of St. Joseph Bay, Florida. In other systems experiencing eutrophication, however, it is possible that increased habitat complexity may have the greater effect on seagrass productivity.

Epiphyte diversity and biomass in the canopy of lowland and montane forests in Ecuador

Epiphyte diversity as well as distribution and composition of epiphytic biomass was investigated in two lowland and two montane rain forests in Ecuador. Species numbers of epiphytes per tree were slightly higher in the montane (22–41 in Los Cedros, 33–54 in Otonga) than in the lowland forests (9–43 in Yasuni, 19–32 in Tiputini), however differences were not significant. In contrast, some epiphyte families did show significant altitudinal differences. The total epiphytic biomass per branch surface decreased from the centre of the crown to the periphery, and was generally higher in the montane (6.0 kg m−2 on central branches in Los Cedros, 1.8 kg m−2 in Otonga) than in the lowland forests (1.3 kg m−2 in Yasuni and 1.8 kg m−2 in Tiputini). Especially, dry weight of bryophytes and dead organic matter was higher in the mountains. In contrast, the biomass of green parts of vascular epiphytes on central branches was about the same in all four forests (0.4–0.6 kg m−2). A comparison with literature data from other study sites of tropical moist forests supports the observation that biomass of vascular epiphytes does not significantly change with altitude. It is discussed, that the high bryophytic biomass in montane compared to lowland forests is a major reason for differences in humus biomass between these forest types.

Effects of nutrient enrichment and small predator density on seagrass ecosystems: An experimental assessment

We used a field experiment to assess the individual and combined effects of removing top predators and enriching water column nutrients (nitrogen‐N and phosphorus‐P) on seagrass ecosystem structure and function. Experiments were conducted in turtlegrass (Thalassia testudinum) habitats in St. Joseph Bay, FL, an aquatic preserve in the northern Gulf of Mexico that exhibits low ambient nutrient concentrations and contains abundant populations of small crustacean and gastropod mesograzers. We stocked 7.0 m 2 enclosures with elevated (≈4ࢤ8× ambient) densities of juvenile pinfish (Lagodon rhomboides), the dominant fish species in local seagrass habitats, to simulate the first‐order effects of large predator reductions, and we used an in situ delivery system to supplement N and P to ≈3× ambient levels in nutrient addition treatments. Monthly determinations of water column nutrients and Chl a, along with measurements of the biomass and abundance of leaf epiphytes and seagrass production, biomass, and shoot and leaf densities were used to evaluate the relative effects of manipulating nutrient supply and altering food web structure.In contrast to our expectations, results showed few significant nutrient effects, or fish × nutrient enrichment effects on any of the parameters measured. However, there were many significant fish effects, most of which were unexpected. As predicted, increased pinfish density reduced mesograzer numbers significantly. Not anticipated, however, was the reduced epiphyte biomass in fish enclosure treatments, apparently brought about by the pinfish consuming significant amounts of epiphytes as well as mesograzers. This reduction in epiphyte biomass produced positive indirect effects on seagrass biomass, shoot number, and rates of primary productivity in pinfish enclosure treatments.Our results also showed important top‐down effects in determining the composition and abundance of seagrass‐associated plants and animals in this pristine environment. Although we did not observe simple trophic cascades, most likely because pinfish fed at more than one trophic level, and because the dense seagrass prevented small grazers from being reduced to low numbers, pinfish produced important changes in the epibiota as well as the seagrasses themselves. These data, while contrasting with studies reporting significant negative nutrient enrichment effects on seagrasses, support the results of recent experimental studies in showing that: (1) small grazers can often control the abundance of epiphytes; and (2) it is unlikely that a full understanding of the consequences of nutrient enrichment for seagrass ecosystems can be gained without knowing how grazer population are regulated.

Criticism of the litterbag technique for the study of aquatic plant decay: Suppression of epiphytic algal biomass.

Recent studies have suggested thiat autotrophs (cyanobacteria and eukaryotic algae) attached to emergent plant detritus are important to the decay of that detritus; however, the litterbag methodology commonly employed for study of plant decay may inhibit epiphytic autotrophs. Thus, the purpose of this study was to examine the change in epiphytic algal biomass on Typha latifolia litter in four types of litter enclosures. The enclosures were designed to provide various combinations of light intensity and invertebrate access to the surface of enclosed Typha litter. Within the enclosures, algal biomass (as chlorophyll-a) on the litter and rate of Typha decay were examined over 133 days (May-October, 1994). Over the entire study, average chlorophyll concentrations on litter incubated in enclosures constructed of fine mesh ranged from 0.41 ± 0.04 to 0.23 ± 0.04 μg cm -2 of detritus, relative to values of 0.63 ±0.07 to 0.75 ± 0.07 μg cm -2 on detritus incubated in coarse-mesh enclosures or open, floating enclosures. The results clearly indicated that autotrophic biomass on Typha litter was inhibited by litter enclosures of fine mesh; consequently, previous studies of aquatic plant decay may have missed contributions to decay processes by this important component of the detrital community.

Monitoring Seagrass Ecosystem Health—The Role of Perception in Defining Health and Indicators

ABSTRACT Thirty‐four seagrass researchers/managers were asked to identify seagrass sites in Cockburn Sound, Western Australia, which they perceived to be healthy or unhealthy, and indicate the basis for these perceptions. The average respondent based their perception on three variables, ranging from ecosystem features to plant attributes. Four variables were considered very important in developing perceptions: canopy cover, shoot density, epiphyte biomass, and the proportion of calcareous epiphytes. Three sites perceived to be healthy and three perceived to be unhealthy were then compared to determine if features indicated as important in developing perceptions about health differed between the sites. None of the four variables considered important by respondents differed statistically between “healthy” and “unhealthy” sites in winter, but shoot length and above ground biomass were different. In summer, two of the important variables (canopy cover and shoot density) differed, along with shoot height, productivity, and leaf area index. Despite their perceived importance, epiphyte features were not different between perceived healthy and unhealthy sites. The study suggests that shoot density, canopy cover, shoot height, above ground biomass, productivity, and leaf area index of P. angustifolia ecosystems differ statistically between sites perceived to be healthy and unhealthy. However, the usefulness of these variables as indicators of seagrass health varies seasonally. Health was clearly a respondent‐dependent concept. The basis of perceptions about health among a group of expert scientists did not correspond strongly to measurable differences between sites. The unwarranted importance placed on epiphytes may be due to previous studies that have reinforced their importance. These observations highlight the role of personal perspective and scientific preconditioning in forming concepts of health, and raise the question of the role that “experts” should be playing in formulating those concepts.

Intertidal mesograzers in field microcosms: linking laboratory feeding rates to community dynamics

Mesograzers (herbivores <2.5 cm) are both diverse and abundant, but their relative effects on intertidal communities have rarely been quantified. Here I examine the effects of crustacean and polychaete mesograzers on two intertidal resources, the red alga Odonthalia floccosa Esp. (Falkenb.) and the epiphytic diatom Isthmia nervosa Kütz. The mesograzers were hermit crabs (Pagurus hirsutiusculus (Dana) and P. granosimanus (Benedict)), amphipods (Hyale frequens Stout and H. pugettensis (Dana)), isopod (Idotea wosnesenskii (Brandt)), juvenile kelp crab (Pugettia producta (Randall)), and polychaete worm (Platynereis bicanaliculata (Baird)). Feeding rates on Isthmia, measured in the laboratory for different consumer species and size classes, scaled allometrically with body mass. Consumption rates were 2-23% of body mass daily on a fresh weight basis. However, feeding rates on Odonthalia did not scale, suggesting that size will not always indicate per capita effect. Mesograzer densities were measured on Tatoosh Island, Washington, USA. The mesograzer predicted to have the largest total effect (P. hirsutiusculus), based on densityxfeeding rate, was neither the most abundant nor the most voracious. The validity of these sorts of predictions depends on how well feeding rates measured in the laboratory approximate per capita effects under field conditions. Predictions were compared to observed effects in field microcosms. Given known numbers of mesograzers, predictions were made about the amount of Isthmia biomass that should disappear over 2 weeks from microcosms (9x9x12 cm) anchored in tidepools. Average per capita effects in field microcosms were correlated with laboratory feeding rates, but, for three species with significant feeding on Isthmia, effects were lower than feeding rates predicted. Feeding trials may overestimate community impact because they fail to account for alternative food, search times, resource productivity and stimulation of growth, or interference from other consumers. Nevertheless, densities of mesograzers can reach sufficiently high levels so that even feeble per capita effects combine to alter biomass of epiphytes and perhaps other small algae.

Are macroinvertebrate communities influenced by seagrass structural complexity?

A study was undertaken within a sub‐tidal Zostera marina seagrass bed (Devon, U.K.), with the aim of elucidating the relationship between seagrass structural complexity and the size and composition of the associated macroinvertebrate community. Samples of macroinvertebrates were recovered from three designated areas of shoot density. Various physical characteristics were measured for individual plants, and an a priori complexity index was determined relevant to the associated target organisms. Resulting data were analysed using linear regression and multivariate techniques. Significant relationships were found between shoot density and number of leaves/shoot, leaf length, stem length and algal epiphyte biomass. Neither the number of species nor abundance of macroinvertebrates was significantly related with the derived complexity index. Multivariate analysis indicated that macroinvertebrate communities from the three areas of shoot density were significantly different, the pattern of macroinvertebrate community composition being best explained by sea‐grass biomass. Linear regression of seagrass biomass with macroinvertebrate number of species and abundance revealed significant positive relationships. Regression also indicated that there was no significant increase in complexity with increasing seagrass biomass. The results suggest that within a seagrass bed the size and composition of the associated macroinvertebrate community is not determined by the structural complexity of the plants, but by the amount of plant available. This finding indicates a simple species‐area relationship, and arguably one brought about as a result of a sampling artefact. Thus, the current paradigm that structural complexity of seagrass is responsible for increased species diversity, can only be justifiably applied to comparisons between seagrass and other habitats, and not within a seagrass bed itself.

Population Dynamics and Reproductive Traits of Phytal Gastropods in Seagrass Bed in Otsuchi Bay, North‐Eastern Japan

Abstract. We studied the population dynamics and reproductive traits of two phytal gastropods, Lirularia iridescens and Hiloa tristis, inhabiting a seagrass bed consisting of two seagrass species, Zostera marina and Zostera caulescens, in Otsuchi Bay, north‐eastern Japan. The main objectives of the study were to (1) determine seasonal and between‐substrata variations in gastropod populations and (2) examine two major factors potentially responsible for the variations, namely space (seagrass) and food (epiphytes). The biomass of Z. marina reached a peak in summer and decreased through autumn, whereas the biomass of Z. caulescens showed little seasonal fluctuation. Epiphyte biomass was maximum in April and remained low from summer to winter on both seagrass substrata. The population densities of both gastropod species increased rapidly due to increases in their new recruits from May to July for L. iridescens, from June to October for H. tristis. Eggs of L. iridescens were found in almost all months of the study period, with a breeding peak in April, whereas oviposition of H. tristis occurred only from June to October. The new recruits of both gastropods grew rapidly, with their abundance decreasing from summer to autumn. The peak densities of new recruits of the two species coincide with that of seagrass biomass rather than epiphyte biomass, and the juveniles grew when the epiphyte biomass was fairly low. Hence, large postrecruitment declines in gastropods may be caused by food shortage. Egg density, size structure and growth rate of both gastropod species were not significantly different between seagrass substrata. Total abundance was not significantly different for L. iridescens. For H. tristis, however, abundance was lower on Z. caulescens than Z. marina during most of the year, mainly due to higher post‐recruitment decline on the former. The ability of L. iridescens to breed continuously may enable them to successfully inhabit two seagrass species with different phenology, whereas the much shorter breeding season of H. tristis, which coincides with the periods of higher Z. marina biomass, may be more adaptive for inhabiting Z. marina than Z. caulescens.

Macrofaunal associations with seagrass epiphytes

Abstract Attached epiphytes often make important contributions to total primary production in seagrass meadows. Additionally, they may increase the spatial complexity of seagrass habitats. Experiments conducted using artificial seagrass units (ASU) manipulated both epiphytic structure and epiphytic food resources. Previous work suggested that the increase in faunal density associated with epiphytes was related to increases in structure, but our results indicate that the primary impact of epiphytes lies in their trophic role. Data showed that epifaunal density was significantly greater in conditioned ASUs fouled with a live community of epiphytes (12 285 individuals m −2 ) compared to ASUs with artificially created epiphytic structure (5099 inds. m −2 ) and to control ASUs (5955 inds. m −2 ). This response to epiphytic trophic resources was significant for most herbivore/omnivore taxa, but not necessarily for filter feeding or predatory epifauna. However, densities of two predatory taxa (fish and mud crabs) were significantly greater where epiphytic biomass was higher, which may reflect their response to increased prey abundance. Additionally, ASUs conditioned with live epiphytes had greater taxa richness than other ASUs. Epiphytic structure appeared to play only a limited role in determining the density of most mobile epifauna, but epiphytic structure appeared to be important in augmenting the settlement of bivalves. By using ASUs we were able to control aspects of blade length and shoot density, but the pre-experiment conditioning of treatments fouled with live epiphytes may have played a role in determining absolute differences in macrofaunal density among ASU treatments. Overall, our work suggests that the trophic role of epiphytes can have a dramatic impact on associated epifaunal communities, although future investigations are needed to assess this relationship more fully.

An Experimental Test of the Capacity of Food Web Interactions (Fish–Epiphytes–Seagrasses) to Offset the Negative Consequences of Eutrophication on Seagrass Communities

A mechanism of competition between epiphytes and seagrasses potentially modulated by grazers was studied in a high-nutrient Thalassia testudinum meadow in the Indian River Lagoon (Florida, U.S.A.). The effects of fish grazing on epiphytes, and likely enhancing T. testudinum growth, was tested through an exclusion experiment. Twelve (2×2m) independent experimental plots were selected within a shallow monospecific bed to which three randomized treatments (exclusion fences, open fences and controls) with four replicates each were assigned. The epiphyte load was monitored on T. testudinum leaves inside the plots from January 1995 to March 1996. Treatment effects occurred during a chlorophyte bloom in March 1995, when the epiphyte biomass was significantly higher inside the exclusion cages than in either of the controls. The composition of the epiphytic community in March 1995 was dominated by sheet-like Enteromorpha and filamentous algae such as Cladophora , which are less resistant to herbivory than the coarsely-branched forms of red algae (e.g. Hypnea , Chondria and Acanthophora) that bloomed subsequently. These results suggest that herbivory change seasonally depending on the availability of different prey species to fish-grazers, which preferentially utilize the fleshy green algae typical of bloom conditions over the thicker coarsely-branched red algae. In the nutrient-rich lagoon the role of top-down interactions in enhancing T. testudinum growth is limited to the reduction of shading by green macroalgae.

Reduced-impact logging effects on commercial non-vascular pendant epiphyte biomass in a tropical montane forest in Costa Rica

Compatibility of different commercial uses of a montane tropical oak–bamboo forest in Costa Rica was assessed for selective logging and harvesting of non-vascular pendant epiphytes, a locally valuable non-timber forest product (NTFP). The non-vascular pendant epiphyte taxa examined were mosses (Pilotrichella flexilis, Phyllogonium viscosum, Zelometeorium sp., Squamidium leucotrichum); liverworts (Frullania convoluta and Frullania spp.); and lichens (Usnea spp.). All of these species have pendant life-forms, and apparently play key roles in water interception, thereby influencing the hydrological balance in tropical montane ecosystems. Since the growth of pendant non-vascular epiphytes conversely depends on fog and mist, these species could be used as indicators of health of the tropical montane forests where they abound. Nine years after careful selective logging, no negative impacts were detected on the biomass of these NTFPs at the heights at which they are commercially harvested (1–3m). This result was established through comparisons of logged and non-logged plots on the basis of abundance (biomass) of the commercial bryophytes and related variables such as substrate length availability and substrate type (shade tolerant, pioneer species, or bamboo, and substrate diameter). Pendant epiphytes were most abundant on thin substrates (branches <1cm in diameter); the highest biomass values per unit substrate length were found on branches of shade-tolerant species.

Fauna vs flora contribution to the leaf epiphytes biomass in a Posidonia oceanica seagrass bed (Revellata Bay, Corsica).

The epiphyte biomass of Posidonia oceanica (L.) Delile leaves is mainly related to the substrate leaf availability. It decreases with increasing depth and increases from winter to summer, following the leaf biomass changes. In Revellata Bay (Gulf of Calvi, Corsica), at shallow depth (10 m in this study) where photophilous algae grow, the fixed epifauna biomass accounts for about one third of leaf epiphytes biomass. At deeper depths in the Revellata Bay (20 and 30 m), where shade-tolerant algae are dominant among epiflora, epifauna may account for more than half the leaf epiphytes biomass.

Effects of fish farming on seagrass ( Posidonia oceanica) in a Mediterranean bay: seagrass decline after organic loading cessation

The effects of fish farming on a seagrass ( Posidonia oceanica) meadow at Fornells Bay, Minorca (Balearic Islands) were studied. Changes in plant and meadow features (e.g. shoot morphology, shoot density, biomass, rhizome growth, nutrient and soluble sugars concentrations…) in three stations along a transect from a disturbed (organic pollution due to fish cultures) to an undisturbed site were assessed. The fish culture had ceased in 1991; however, seagrass decline, already reported in a previous study for the period 1988–1990, was still taking place at the time of sampling (July 1994). Differences between stations were very clear; the station closest to the fish cages showed reduced shoot density, shoot size, underground biomass, sucrose concentration and photosynthetic capacities. In contrast, shoots from the most polluted station showed higher P-concentration in tissues and higher epiphyte biomass than the other two. Since water conditions had recovered completely by the time of the sampling mission, it is proposed that the persistence of the seagrass decline was due to the excess organic matter remaining in the sediment.

Effects of water-column enrichment on the production dynamics of three seagrass species and their epiphytic algae

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 179:201-213 (1999) - doi:10.3354/meps179201 Effects of water-column enrichment on the production dynamics of three seagrass species and their epiphytic algae Donna J. Wear1,*, Michael J. Sullivan2, Allen D. Moore2, David F. Millie3 1Department of Biology, Augusta State University, 2500 Walton Way, Augusta, Georgia 30904-2200, USA 2Department of Biological Sciences, PO Drawer GY, Mississippi State University, Mississippi State, Mississippi 39762, USA 3US Department of Agriculture, Agricultural Research Service, Southern Regional Research Center, 1100 Robert E. Lee Boulevard, New Orleans, Louisiana 70124, USA *E-mail: dwear@aug.edu ABSTRACT: Monospecific beds of the seagrasses Halodule wrightii, Syringodium filiforme and Thalassia testudinum were enriched with a slow-release OsmocoteTM (N-P-K) fertilizer from August 1993 through September 1994. Primary production rates (as 14C uptake), biomass (dry weight), and chlorophyll a (chl a) (measured by HPLC) of epiphytes in enriched beds were significantly greater than those of epiphytes in control beds. Based on microscopic observations, the dominant epiphytic algae were diatoms and red and brown algae. Populations of the brown alga Myriotrichia subcorymbosa and the red alga Acrochaetium flexuosum increased greatly in enriched plots of all 3 seagrass species. Multiple linear regression supported observational data in that pigment signatures selected for the dominant epiphytes (fucoxanthin, zeaxanthin, and violaxanthin) explained 97% of the variation in chl a. A strong correlation between measured and predicted chl a (r = 0.98) suggested that chl a is an excellent indicator of epiphytic biomass in this system. Production rates of blades increased in enriched plots relative to controls but biomass of blades was unaffected. The strong response of epiphytes to enrichment suggests that cultural eutrophication could pose a threat to seagrass beds of Big Lagoon, Perdido Key, Florida, USA. Negative effects could be manifested as a reduction in the coverage of shallow-water sediments by seagrass beds and/or the elimination of 1 or 2 species, possibly converting Big Lagoon into a seagrass monoculture. KEY WORDS: Eutrophication · Primary production · Epiphytic algae · Seagrasses · Pigments Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 179. Publication date: April 15, 1999 Print ISSN:0171-8630; Online ISSN:1616-1599 Copyright © 1999 Inter-Research.

Commercial moss harvest in northwestern Oregon: biomass and accumulation of epiphytes

As concern over the sustainability of commercial moss harvest in the Pacific Northwest has grown, so too has the need to develop methods for estimating the rate of harvest, the biomass inventory, and the rate of accumulation of commercially harvestable epiphytes. We estimated biomass and net moss accumulation in 10 sites in both the historically heavily moss-harvested Coast Range and the historically relatively unharvested Cascade Range of northwestern Oregon. Harvestable epiphyte biomass in the lower canopy (<2 m above ground) ranged from c. 120 to 1470 kg ha −1 in the Coast Range, and 25 to 1068 kg ha −1 dry weight in the Cascade Range. The greater biomass at the Coast Range sites resulted from a higher density of suitable substrates, with epiphyte mass per unit area of substrate roughly equal in the two sets of sites. Epiphyte mass accumulation on vine maple Acer circinatum was extremely variable within and between sites, especially in the Coast Range. A model describing the factors affecting epiphyte mat accumulation is described. We recommend active management to conserve epiphytic bryophytes through promoting hardwood tree and shrub substrates, restricting moss harvest to the lower canopy, controlling the rate of harvest, and instigating rotation periods.

Some Observations on the Biomass and Distribution of Cryptogamic Epiphytes in the Upper Montane Forest of the Rwenzori Mountains, Uganda

Some Observations on the Biomass and Distribution of Cryptogamic Epiphytes in the Upper Montane Forest of the Rwenzori Mountains, Uganda

Some observations on the biomass and distribution of cryptogamic epiphytes in the upper montane forest of the Rwenzori Mountains, Uganda

Measurements were made of the percentage cover, biomass and species-richness of cryptogamic epiphytes growing upon mature Phillipia phillipia stands in the ericaceous (upper montane) forest of the Rwenzori Mountains, Uganda. Macrolichens, especially Usnea spp., dominated the upper canopy, while a range of large cushion-forming hepatics (e.g. Chandonanthus, Herbertus, and Plagiochila species) dominated the lower canopy. The distribution of cryptogams was largely controlled by light intensity and phorophyte age Detailed studies of a felled Phillipia revealed twenty-nine epiphyte species (two algae, fourteen bryophytes, eleven lichens and two ferns). The forest appears to be moderately species-rich with a small number of species providing a large proportion of the cryptogam biomass. Total biomass of the epiphytes was close to 1 tonne ha−1, representing about 10% of the above-ground standing crop. Concentrations of N, P and K in the epiphytes were estimated as 10, 1, and 3 kg ha−1 respectively. The lichens and bryophytes contained about 2% and 8% respectively of the total above-ground nutrients Microclimate measurements below the forest canopy demonstrated constant high humidity with suboptimal radiation. Air temperature below the canopy averaged 7.6°C (range 4–9.5°C) during a 10-day period, and increased slightly with canopy height. Evaporation below the forest canopy showed a significant decline as altitude increased from 2300 to 3600 m.

Temporal variations in biomass of the algal epiphytes associated with the dominant submersed macrophytes in Lake Okeechobee, Florida (USA)

(1998). Temporal variations in biomass of the algal epiphytes associated with the dominant submersed macrophytes in Lake Okeechobee, Florida (USA) SIL Proceedings, 1922-2010: Vol. 26, No. 4, pp. 1716-1720.

Structure of major seagrass beds from three coral reef atolls of Lakshadweep, Arabian Sea, India

Detritus-based marine ecosystems such as mangrove and seagrass are of immense ecological importance. Major seagrass meadows from three coral atolls of the Lakshadweep group (Arabian Sea) were studied for their floral components. Seagrass beds were heterogeneous, comprising mainly of Thalassia hemprichii and Cymodocea rotundata, in Agatti and Kavaratti and it was observed to be monospecific ( T. hemprichii) in the Kalpeni lagoon. Maximum (0.34 km 2) and minimum (0.005 km 2) extent of seagrass beds were observed in Kavaratti and Agatti lagoons, respectively. Seagrass weight (dry) of 43.97, 30.88 and 0.74 t were estimated from Kavaratti, Kalpeni, and Agatti, respectively. Maximum biomass occurred from 0–2 m depth, mainly contributed by the aboveground shoots, and was found to be negatively correlated with depth ( r=0.71, p<0.05). Sediments were devoid of seed reserves indicating seagrass growth mainly by vegetative propagation. Epiphytes, on an average, contributed 7.5% of the seagrass biomass and were dominated by algae such as Melobesia spp., Microcoleus lyngbyaceus and Ceramium spp. Epiphytic biomass, too, decreased with increasing depth. Associated marine algae were represented by 66 species, dominated by rhodophytes.