Biomass accumulation and shading effects of epiphytes on leaves of the seagrass, Heterozostera tasmanica, in Victoria,Australia

A method is described for estimating the rate of accumulation of epiphyte biomass on leaves of the seagrass, Heterozostera tasmanica (Martens ex Aschers.) den Hartog and for estimating the effect of epiphyte biomass on photosynthesis of the seagrass. Epiphyte biomass was determined by comparison of the weight per unit area of epiphyte-covered and epiphyte-free leaf blades. Epiphyte weight increased as age of the seagrass leaves increased. Linear regression on epiphyte biomass vs. leaf age estimated the rate of biomass accumulation. Rates varied from 5.7 to 104 μg epiphyte dry weight per cm² of leaf surface per day at three sites in Western Port and Port Phillip Bay, Victoria. Rates of accumulation of epiphyte biomass were generally higher during December through March (summer) than in May (autumn), August (winter) or October (Spring). Light attenuation by epiphytes increase linearly with biomass. The rate of biomass accumulation of epiphytes was compared with leaf growth rate, ambient photon flux density in H. tasmanica beds and the photosynthesis—photon flux density curve of H. tasmanica. This comparison demonstrated that epiphyte biomass can accumulate fast enough to shade H. tasmanica leaves and significantly reduce the time (to less than one half of the leaf life span) in which positive net photosynthesis of the leaf blade is possible.     

An annual cycle of biomass and productivity of Vallisneria americana in a subtropical spring-fed estuary

An annual cycle of biomass and productivity of wild celery (Vallisneria americana) was studied in Kings Bay, FL, USA. In situ growth rates were measured monthly between March 2001 and June 2002 in high-density stands, using a modified hole-punching technique, and applied to shoot density data to obtain areal estimates of production. Mean shoot density varied greatly over the study period, ranging between 200 and 800 shoots m⁻². Mean total biomass ranged between 162 and 1013 g m⁻², with aboveground material comprising, on average, 70% of total biomass. Total annual estimated production of new attached shoots was 519 g m⁻². Leaf growth rates peaked at >50 mg shoot⁻¹ d⁻¹, and mass-specific leaf growth ranged 0.6–1.8% d⁻¹. Annually, individual shoots produced 7.4 g of leaf material and completely replaced standing leaf biomass 3.5 times. Areal leaf production was highest in late spring/summer of 2001, and ranged between 3.6 and 23.0 g m⁻² d⁻¹. Annual total leaf production was 2704 g m⁻². Seasonality was not apparent in most variables monitored monthly; only 1 of the 64 relationships we examined between environmental variables (nutrients, chlorophyll a, and irradiance) and Vallisneria biological variables were significant, with relative growth rate increasing linearly with irradiance. Peak biomass and productivity of Vallisneria in Kings Bay were high compared to literature values for other Vallisneria populations as well as global averages for well-studied seagrasses, emphasizing the potential importance of Vallisneria to whole ecosystem functioning in springs, lakes, and oligohaline reaches of many estuaries.     

Leaf growth in the seagrass Syringodium filiforme Kütz

Field measurements made during the summer of 1982 in the Indian River lagoon, Florida, showed that Syringodium filiforme Kütz. displays a consistent pattern of growth. The cylindrical leaves lengthen at initial constant rates from a basal region, slow when approaching maturity, and finally cease growing. Elongation rates of individual blades varied by a factor of 3.6, from 0.86 to 3.11 cm day^?1, but were usually similar within a factor of 1.5 for leaves growing on the same shoot. Leaf diameter was primarily determined by growth in the basal meristem region and varied from 0.80 to 1.47 mm during growth of an average 40 cm blade. Syringodium also partitions growth among leaves in a consistent manner. On an upright shoot that bears 1–3 leaves, growth is almost totally confined to the youngest leaf with a new leaf starting as the previous leaf stops. For productivity studies of Syringodium, monitoring growth of the youngest leaves on several leaf shoots will give accurate estimates of mean growth rates.     

Aspects of production and biomass of four seagrass species (Cymodoceoideae) from Papua New Guinea

Biomass and production data of the seagrasses Cymodocea serrulata (R. Brown) Aschers. and Magnus, Cymodocea rotundata Ehrenb. et Hempr. ex Aschers., Halodule uninervis (Forssk.) Aschers. and Syringodium iksoetifolium (aschers.) Dandy were collectede in monospecific stands in Bootless Inlet, Papua New Guinea. Cymodocea serrulata and Cymodocea rotundata were studied from November 1980 to November 1981. Total annual mean biomass was 354 and 201 g ADW m⁻², respectively. The largest proportion of these biomass values was contributed by the rhizomes (49 and 36%, respectively) and leaf biomass was ± 30% for both species. Halodule uninervis was studied at an intertidal and a subtidal site. The highest total annual mean biomass (600 g ADW m⁻²) was recorded at the intertidal site, of which 85% was found below ground. The largest proportion of the biomass, at both sites, was contributed by the below-ground vertical axes of the shoots. The biomass of the rhizomes was relatively low (9–12%) for Halodule uninervis. Proportionally, the largest above-ground biomass (40%) was recorded for Syringodium isoetifolium, of which the annual mean biomass was 481 g ADW m⁻².Total production (above and below ground) was 4.9 and 3.0 g ADW m⁻² day⁻¹ for Cymodocea serrulata and Cymodocea rotundata, respectively. Approximately 70% was production of leaves. Total production amounted to 6.0 and 4.0 g ADW m⁻² day⁻¹ for Halodule uninervis at the intertidal and subtidal sites, respectively. The maximum production was recorded for Syringodium isoetifolium, 60% of the 9.0 g ADW m⁻² day⁻¹ was contributed by the leaves. All species reached the maximum production during February and March, when the water temperatures were highest and water was retained above all sites, at all times. The increase of leaf production was mainly due to the increase in biomass of the mature leaves. Significant changes in the plastochrone interval of the leaves were not observed during this period.     

Matter-economical roles of the evergreen foliage ofAucuba japonica,an understory shrub in the warm-temperate region of Japan

Leaf demography and productivity ofAucuba japonica, an understory shrub in the warm-temperate region, were examined and dry matter economy was analyzed to evaluate the roles of the evergreen foliage. Turnover of leaves occurred during a short period in spring. The mean leaf life span was about 2.6 years. Annual NAR (net assimilation rate) of each sample shoot was calculated from the biomass and the total dead mass estimated from scars of leaves and floral parts. The average NAR was 1.34±0.22 g·g⁻¹·yr⁻¹. The ratio of dry matter produced by leaves during their whole life span to the initial investment was 3.45±0.37. The annual NAR calculated for individual plants was negatively related to the life span of their leaves. The seasonal change in SLW (specific leaf weight) showed that the reserve material in leaves was accumulated from autumn to early spring and was consumed for the growth of new organs in the following season. The dry matter withdrawn in spring from the overwintering foliage amounted to 40% of dry mass of the new organs developed.     

Leaf growth and population dynamics of intertidal Zostera japonica on the western coast of Korea

Leaf production and population dynamics of Zostera japonica were examined at three elevations of an intertidal transect in Seungbongdo Island on the western coast of Korea. Morphometrics, shoot density, biomass, leaf production, reproductive effort and environmental factors were monitored from October 2001 to October 2002. Z. japonica grew well in the lower intertidal zone from 0.2 to 1.0 m above mean chart datum. The upper station (St. 1) exhibited a finer sediment grain size and richer organic content than the middle (St. 2) and lower stations (St. 3). The size of shoots and leaves was significantly greater at St. 1 than at St. 3, whereas the rhizome internodes were longer at St. 3. Despite differences in morphological characteristics among three stations, seagrass biomass and shoot density were not significantly different among study sites. Shoot density, biomass, morphometrics and leaf productivity exhibited clear seasonal variations, which varied along with seasonal changes of water and air temperature. Leaf productivity measured by the clip and reharvest method was highest in September (4.3 g DW m⁻² d⁻¹) and lowest in February (0.2 g DW m⁻² d⁻¹). Reproductive shoots rapidly increased to maximum density along with the high water temperature in July to September. In the intertidal zone, Z. japonica exhibited faster vegetative growth on muddy sand than on sand, probably due to the difference in nutrient supply. The seasonal changes of water and air temperature were considered to play an important role in the seasonal leaf growth of Z. japonica.     

Grasstree (Xanthorrhoea preissii ) leaf growth in relation to season and water availability

Abstract Water stress usually arrests growth of even the most deep‐rooted species during summer drought in Mediterranean‐type climates. However, scant evidence suggests that grasstrees may represent an unusual exception. We used weather data and plant water potential to investigate the relationship between leaf growth and season in the grasstree, Xanthorrhoea preissii Endl. (Xanthorrhoeaceae). Leaf production in two contrasting habitats revealed continuous annual growth, oscillating between maximum rates (2.5–3.2 leaves/d) in late‐spring to autumn, to a minimum rate of 0.5 leaf/d during winter but never stopping. While the rate of leaf production during the fast‐growth season was positively correlated with temperature above 17–18°C, leaf elongation commenced substantially earlier in the year (from 12°C). Leaf water potentials cycled annually, with predawn readings commonly measured as zero during winter–spring and as low as ?1.26 MPa during summer, but never indicating stress by exceeding the turgor loss point. Leaf death was synchronized with summer drought. The fast (summer) growth period was characterized by rapidly fluctuating leaf production, particularly in banksia woodland, where plant growth reliably responded quickly to >18 mm of rainfall. Within 24 h of 59 mm of simulated rainfall, grasstrees in banksia woodland showed a marked increase in water potential, and leaf production reached 7.5 times the controls, confirming their capacity to respond to temporary spasmodic summer rains. Rainfall was the best climatic variable for predicting woodland grasstree leaf production during summer, whereas leaf production of forest grasstrees was most closely correlated with daylength. This plastic response of grasstrees between seasonal weather extremes is relatively rare among other mediterranean floras, and has implications for a recently proposed technique for ageing grasstrees.     

Leaf growth and population dynamics of intertidal Zostera japonica on the western coast of Korea

Leaf production and population dynamics of Zostera japonica were examined at three elevations of an intertidal transect in Seungbongdo Island on the western coast of Korea. Morphometrics, shoot density, biomass, leaf production, reproductive effort and environmental factors were monitored from October 2001 to October 2002. Z. japonica grew well in the lower intertidal zone from 0.2 to 1.0 m above mean chart datum. The upper station (St. 1) exhibited a finer sediment grain size and richer organic content than the middle (St. 2) and lower stations (St. 3). The size of shoots and leaves was significantly greater at St. 1 than at St. 3, whereas the rhizome internodes were longer at St. 3. Despite differences in morphological characteristics among three stations, seagrass biomass and shoot density were not significantly different among study sites. Shoot density, biomass, morphometrics and leaf productivity exhibited clear seasonal variations, which varied along with seasonal changes of water and air temperature. Leaf productivity measured by the clip and reharvest method was highest in September (4.3 g DW m⁻² d⁻¹) and lowest in February (0.2 g DW m⁻² d⁻¹). Reproductive shoots rapidly increased to maximum density along with the high water temperature in July to September. In the intertidal zone, Z. japonica exhibited faster vegetative growth on muddy sand than on sand, probably due to the difference in nutrient supply. The seasonal changes of water and air temperature were considered to play an important role in the seasonal leaf growth of Z. japonica.     

A preliminary study of the seagrass Thalassodendron ciliatum (Forssk.) den hartog from Eastern Indonesia. Biological results of the snellius II expedition

Two dense meadows of the seagrass Thalassodendron ciliatum (Forssk.) den Hartog were sampled during the Indonesian—Dutch Snellius II expedition to Eastern Indonesia. Production data were obtained from one of these meadows. The production of leaf biomass was measured by the leaf marking technique of Zieman and by the plastochrone interval method. The two methods reached comparable results. The production of leaf tissue was 4.2 mg ADW shoot^?1 day^?1. The production of rhizome biomass was calculated in a similar way, based on the plastochrone interval of rhizome nodes. The production of the meadow, exclusive of the production of roots and fruits, amounted to 4.5 g ADW m^?2 day^?1. A significant correlation between the growth rates of rhizomes and leaves was observed. Biomass data from the second site are given.     

Mass loss,fungal colonisation and nutrient dynamics of Phragmites australis leaves during senescence and early aerial decay

This study examined the mass loss, fungal biomass, and nutrient dynamics of standing Phragmites australis leaf blades during senescence and early decay in littoral reed stands of two hardwater lakes. Green living leaves were tagged at defined canopy heights in early autumn (late August or early September) and periodically collected until all leaf blades had fallen off the parent shoot. Samples were analysed for leaf dry mass remaining, fungal biomass associated with leaves (ergosterol concentrations), and nitrogen and phosphorus concentrations. Considerable mass loss of leaves occurred in the standing position (up to 28%). Nitrogen and phosphorus concentrations of leaves decreased substantially with time (by 39–77%), indicating that a major portion of these nutrients was translocated to the rhizome during senescence. Fungal biomass associated with leaves increased during the study period, reaching an estimated maximum of about 40 mg g⁻¹ of leaf dry mass. Fungal biomass was negatively correlated with leaf N and P concentrations. The observed patterns of leaf mass loss, nutrient dynamics, and fungal biomass were consistent with the successive senescence and death of leaves from the shoot base to its tip. The results of this study point to a notable mass loss of P. australis leaf blades in the standing position, which appears to be mediated by both plant and microbial processes. Nutrient dynamics, in contrast, appear to be largely governed by plant processes.     

A comparison of the annual production and biomass in three monospecific stands of the seagrass Thalassia hemprichii (Ehrenb.) aschers.

Annual production and biomass data were collected in three seagrass communities of Thalassia hemprichii (Ehrenb.) Aschers. from Papua New Guinea. Leaf growth rates, determined by the marking technique, resulted in a growth rate of 8.3 mm day^?1 for the youngest leaves. Production of above-ground plant parts was assessed by the plastochrone interval. The annual mean values were 9.3, 10.0 and 9.9 days for Sites 1, 2 and 3, respectively. Annual mean total above-ground production amounted to 2.1 mg ADW shoot^?1 day^?1 at Site 1, and 5.5 and 4.5 mg ADW shoot^?1 day^?1 for Sites 2 and 3, respectively; 73–89% of the total net production was contributed by the leaves. Rhizome production was correlated to the plastochrone interval of the leaves. Annual mean biomass of leaves amounted to 16–27% of the total biomass. The mean biomass of the other plant parts remained constant during the year. The annual mean turnover time of the different plant parts (above- and below-ground) varied considerably between the sites.     

Factors controlling Zostera marina L. growth in the eastern and western Pacific Ocean: Comparisons between Korea and Oregon,USA

Zostera marina distribution is circum-global and tolerates a wide range of environmental conditions. Consequently, it is likely that populations have adapted to local environmental conditions of light, temperature and nutrient supply. We compared Z. marina growth dynamics over a 2-year period in relation to environmental characters at Jindong Bay, South Korea and Yaquina Bay, Oregon, USA. Water temperature in Jindong Bay showed stronger seasonal variation (summer–winter ΔT = 20 °C) than in Yaquina Bay (summer–winter ΔT < 5 °C). Underwater irradiance in Jindong Bay exhibited a winter maximum, while in Yaquina Bay underwater light exhibited a summer maximum. Integrated annual underwater irradiance during 2003 was 2200 and 1200 mol photons m⁻² year⁻¹ in Korea and Oregon, respectively. Z. marina shoot density, biomass and integrated production were not significantly different between the two study sites. Seasonal Z. marina growth in Jindong Bay appeared to be controlled by temperature and light, while the growth pattern in Yaquina Bay suggested light regulation. Several seagrass parameters were correlated to phosphate concentrations, even though nutrients did not appear limiting. Despite differences in environmental factors, relative growth rates and temporal growth dynamics between study sites, integrated annual leaf production was quite similar at 335 and 353 g DW m⁻² year⁻¹ in the Jindong and Yaquina Bay study sites. We suggest that Z. marina net productivity is acclimated to the local environmental conditions and may be a general characteristic of temperate seagrass populations.     

Leaf vs. epiphyte nitrogen uptake in a nutrient enriched Mediterranean seagrass (Posidonia oceanica) meadow

In situ nitrogen uptake by leaves and epiphytes was studied in a Mediterranean seagrass (Posidonia oceanica) meadow impacted from a fish farm and a pristine meadow, using ¹⁵NH₄ and ¹⁵NO₃ as tracers. In the impacted meadow both leaves and epiphytes yielded higher N concentrations and showed higher specific N uptake, suggesting a linkage between N uptake and its accumulation. Epiphytes took up N faster than leaves in relation to their corresponding biomass, but when assessed per unit area, N uptake was higher in leaves. Leaf N uptake was negatively correlated with epiphyte N uptake. With increasing epiphyte load on leaves, N leaf uptake decreased while N epiphyte uptake increased, indicating that epiphyte overgrowth hinders N uptake by P. oceanica leaves. Epiphyte contribution to total N uptake increased, while that of leaves decreased at the impacted meadow. However, 2-3 times less N was transferred daily from the water column to the benthic compartment, through seagrass and epiphyte uptake on total, at the impacted meadow. Therefore, it is probably still the loss of the key species - the seagrass - which plays the most important role in N cycling in seagrass ecosystems.     

Effects of elevated temperature on seasonal in situ leaf productivity of Thalassia testudinum Banks ex König and Syringodium filiforme Kützing

Net leaf productivities of Thalassia testudinum Banks ex König and Syringodium filiforme Kützing, measured in situ over a 1-year period in a sub-tropical estuary that receives thermal addition from a local power plant, were significantly temperature dependent. Primary production in both species followed seasonal temperature variation, with increase in leaf dry weight as a proportion of total leaf biomass ranging from 0.12% to 2.54% day^?1 for T. testudinum and 0.33% to 3.80% day^?1 for S. filiforme. From September to May, S. filiforme exhibited significantly higher productivity at the thermally-impacted (experimental) station than at the control station. However, from June to August, S. filiforme productivity at the experimental station was significantly lower than at the control station. T. testudinum productivity showed similar trends, but interstation differences were not statistically different. Maximal growth occurred between 23 and 29°C for S. filiforme and 23 and 31°C for T. testudinum. Thus, the thermal addition generally enhanced the seagrass productivity of both species in the autumn, winter, and spring, but reduced that of S. filiforme in the summer, as the optimal temperature range of this species was exceeded. The fact that T. testudinum exhibited a less marked response to the thermal addition and had a greater optimal temperature range than S. filiforme supports its status as the more eurythermal of the 2 species.     

Qualitative and quantitative aspects of the epiphytic component in a mixed seagrass meadow from Papua New Guinea

During 1982, structural and functional aspects of the epiphytic component in a tropical mixed seagrass meadow, have been investigated for each seagrass species separately. This meadow consisted of the seagrasses Thalassia hemprichii (Ehrenb.) Aschers., Cymodocea serrulata (R.Br.) Aschers. et Magnus, C. rotundata Ehrenb. et Hempr. ex Aschers., Halodule uninervis (Forssk.) Aschers. and Syringodium isoetifolium (Aschers.) Dandy.No significant differences were observed in floristic composition, number of algal species, abundance and diversity of the epiphytic component. On an area basis, annual mean above-ground biomass (seagrass leaves and epiphytes), amounted to 82 g ADW, of which 18% could be ascribed to the epiphytic component. The contribution of the epiphytic component to the annual mean above-ground production ranged from 16% on leaves of Thalassia hemprichii to 33% on leaves of Cymodocea serrulata. Total annual mean epiphyte production was 4.6 g ADW m⁻² sediment surface day⁻¹ (19%).When including the macroalgal component of this mixed seagrass meadow, total annual mean above-ground plant biomass amounted to 93 g ADW (212 g DW) on an area basis, of which the epiphytes contributed 15.5% (28.5% DW), the macroalgal component 12% (32.5% DW) and the seagrass leaves 72.5% (39.5% DW). Aspects of the epiphytic component (e.g., floristic composition, abundance, biomass and production) in monospecific and mixed seagrass communities are discussed.     

Annual production of leaf-decaying fungi in a woodland stream

1. Fungi are thought to be important mediators of energy flow in the detritus-based food webs of woodland streams. However, until recently, quantitative methods to assess their contribution have been lacking. Growth rates of leaf-decaying fungi can be estimated from rates of acetate incorporation into ergosterol which, together with estimates of fungal biomass from ergosterol concentrations, enables calculation of fungal production. In this study, I used this method to estimate total production of leaf-decaying fungi over an annual cycle in a small woodland stream, Walker Branch, Tennessee, U.S.A. To calculate fungal biomass and production on an areal basis, I determined the amount of leaf litter occurring in the stream by sampling transects randomly selected in each of ten 10-m sections every 20–50 days. Subsamples of leaves chosen from five of the transects were used to determine ergosterol concentrations and in situ rates of acetate incorporation into ergosterol. 2. Leaf litter, fungal biomass m^–2, and fungal production m^–2 were highly seasonal. Leaf litter ranged from 249 g m^–2 in November to less than 5 g m^–2 during the summer. Fungal biomass as percentage of leaf litter ranged from 4.4 to 8.8% during the year, but on an areal basis ranged from 11 to 13 g m^–2 during November to January to 0.25 g m^–2 in June, primarily due to the seasonal variation in amount of leaf litter present. Fungal growth rates averaged 2.6% day^–1 (0.9–7.0% day^–1) during the year. Daily production of leaf-decaying fungi ranged from 0.49 g m^–2 in November, when the amount of leaf litter was at its maximum, to 0.006 g m^–2 during the summer when the amount of leaf litter was low. Annual production of leaf-decaying fungi was 34 g m^–2, with an annual production to biomass ratio (P/B) of 8.2. 3. Fungal spore concentrations in the stream were also seasonal and were correlated with amount of leaf litter m^–2 and fungal biomass m^–2. Spore concentrations varied between one and four spores ml^–1 throughout most of the year, but increased to eighteen spores ml^–1 shortly after the greatest amount of leaf litter was present in the stream during November.     

Development of a ‘sediment-stress’ functional-level indicator for the seagrass Halophila ovalis

Understanding mechanistic relationships between seagrass and their environmental stressors should be considered for effective management of estuaries and may inform on why change has occurred. We aimed to develop indicators for seagrass health in response to sediment conditions for the Swan-Canning Estuary, south-west Australia. This article describes the development of a new sediment-stress indicator, relating aspects of seagrass productivity with sediment sulfur dynamics. Sulfur stable isotope ratio and total sulfur were measured monthly within the roots, rhizomes and leaves of Halophila ovalis, and significantly varied across sites and months. The growth of seagrass over the summer months appeared restricted by sediment condition, with growth of seagrass lower when sediment derived sulfur and/or total sulfur within rhizome of leaf tissues was higher. H. ovalis appeared quite tolerant of sulfide intrusion within the root compartment, but growth was compromised when sulfide breached the root–rhizome barrier. The tightest correlation between potential sulfur metrics and seagrass growth was observed for the ratio (δ³⁴S_leaf + 30)/(TS_leaf), and it is this ratio that we propose may be a useful sediment-stress indicator for seagrass. The study also highlights that sediment condition needs to be considered at the meadow scale.     

DIFFERENCES IN LEAF STRUCTURE,CHLOROPHYLL, AND NUTRIENTS FOR THE UNDERSTORY TREE ASIMINA TRILOBA

To investigate differences in leaf structure, chlorophyll and nutrients on terminal branches of the understory tree Asimina triloba, the first (proximal) and the last (distal) leaves to develop in the spring were compared. Proximal leaf expansion was completed before the overstory canopy was fully closed but distal leaf expansion occurred during and after the development of the overstory canopy. Fully expanded proximal leaves were 76% smaller in area, were 18% thicker and had 36% more stomates per m of leaf area when compared to distal leaves. In addition, maximum stomatal conductance to water vapor was greater (150 vs. 120 mmol m^−-2s^−-1) and the minimum PPFD required for maximum conductance was higher (200 vs. 150 μmol m^−-2s^−-1) for the proximal leaves. Chlorophyll content was also greater for proximal leaves, but nitrogen and phosphorus contents were lower throughout the entire summer. Seasonal measurements indicated an increase in chlorophyll a content and reductions in nitrogen content throughout the summer growth period for leaves from both positions. The results suggest that distal and proximal leaves differed physiologically and that the measured differences were related to the changing irradiance environment during leaf development. The time of leaf expansion, as indicated by leaf position on the branch, may be an important consideration when examining the water and photosynthetic relations of understory trees.     

A comparison of hole punch and needle punch methods for the measurement of seagrass productivity

Seagrass productivity, as leaf extension, was measured using the hole punch and needle punch techniques. These methods have been widely implemented to determine seagrass leaf extension rates, yet there is no evidence in the literature of a comparison between methods. The hole punch method involves removing part of the basal area of a seagrass leaf and it was proposed that this measurement technique may affect the leaf extension rates that are being measured. Leaf extension rates were measured in Posidonia sinuosa meadows off the coast of Perth, Western Australia. There were no significant differences in seagrass leaf extension between the two methods. The hole punch method is favoured, as measurement of incremental leaf growth is facilitated by the obvious hole left by the punch. The needle punch method leaves lesions on seagrass leaves that are easily confused with other lesions, possibly left by invertebrate grazers. These findings are likely to be applicable to other straplike seagrass species, though a similar comparison is recommended in the initial stages of a study.