Settlement of seaweeds on coastal structures

Coastal structures are constructed principally to protect the coast line. However, these structures also can act as artificial substrata for seaweeds. In particular, armor blocks, such as tetrapods, prove to be good algal substrata. Our field observations on the vegetation and standing crop of seaweed communities on armor blocks led us to the following conclusions: 1) Ecklonia cavacommunities grew on tetrapods that had been placed to coincide with the maturation period of E. cava. The communities have been maintained for more than four years. 2) The standing crop of seaweeds on an offshore breakwater composed of tetrapods placed seven years before was almost the same as that found under natural conditions. 3) Variations in roughened surfaces (pebbles or scores and grooves 3 or 46 mm wide) did not affect the growth of Sargassum spp. However, a greater number of Ecklonia stolonifera plants were observed attached to roughened surfaces compared to smooth surfaces.     

Seasonal changes in taxon richness and abundance of mobile invertebrates inhabiting holdfast of annual kelp Ecklonia radicosa (Phaeophyceae,Lessoniaceae) at the central Pacific coast of Japan

To investigate seasonal changes in the taxon richness and abundance of mobile invertebrates inhabiting holdfasts of the warm temperate annual kelp Ecklonia radicosa, five holdfasts were collected monthly at the central Pacific coast of Japan from April to November 2014. During the study period, there was little variation in holdfast height and diameter, which ranged from 5.9 to 8.5 cm and from 7.1 to 10.8 cm, respectively. In total 7087 animals were collected from 40 holdfasts (177.2 individuals inds./holdfast, on average). The number of mobile invertebrates gradually increased from May (15 ± 9.9 inds./holdfast) to August (346 ± 152.5 inds./holdfast), with over 300 inds./holdfast until October before rapidly decreasing in November (110 ± 85.6 inds./holdfast). Similarly, taxon richness increased gradually from April (4.3 ± 1.0 taxa/holdfast) to August (11.0 ± 3.7 taxa/holdfast), and decreased in November (8.6 ± 2.3 taxa/holdfast). Interestingly, hundreds of mobile invertebrates inhabited holdfasts of kelp plants that had shed their blade in October and November. Taxon composition from August to October and the number of invertebrates from July to November were comparable to data previously reported for perennial kelps. In this study, the importance of annual Ecklonian species as biogenic habitats was demonstrated for the first time.     

Cultivation of the two perennial brown algae Ecklonia cava and E. stolonifera for abalone feeds in Korea

Ecklonia cava and Ecklonia stolonifera are perennial brown algae that form sea forests off the coast of Korea. Both species are cultured to supply a summer feed for the abalone industry. Recent expansion of the abalone industry in Korea has been bringing an increase in demand for fresh algal supply. Zoospores of the two algae were seeded in October 2006 on seed frames coiled with 100 m of seed fibers. After 2 months of indoor culture and 2 months of intermediate culture, growth and production of the two algae were compared during their main cultivation period from March 2007 to June 2008, in the culture ground in Wando, Korea (34°26′18.68″ N, 127°05′43.88″ E), in situ. Growth rate of E. cava and E. stolonifera was 1.058 and 3.089 mm day^?1, respectively. The mean production of E. stolonifera obtained from the culture ropes was ca. 12 kg wet wt. m^?1 of culture rope while production of E. cava was ca. 3 kg wet wt. m^?1 of culture rope. The difference in production was attributed from the different growth strategies of the two algae, with only E. stolonifera being able to regenerate blades from the holdfast. The ability to regenerate blades from the holdfast therefore makes E. stolonifera the preferred species for biomass production for abalone feeds. In a 120-day feeding experiment, growth rate, weight gain, and survival rate of abalone showed that E. cava and E. stolonifera feeds could provide an alternative feed to Saccharina japonica during summer months.     

The mass cultivation of Ecklonia stolonifera Okamura as a summer feed for the abalone industry in Korea

The mass cultivation of Ecklonia stolonifera Okamura was studied as a possible summer feed for the abalone industry in Korea for the period between August and November when Undaria and Laminaria are not available. Experiments were conducted to investigate the optimal conditions for artificial seed production and mass cultivation of this species. Seedlings of E. stolonifera were reared in an indoor tank for 60 days until they were around 500 μm in length. Following indoor tank culture, the seedlings were transferred in situ to a nursery culture area for 2 months, before begin transferred to the main grow-out area. The maximum growth and development of young thalli in nursery culture area occurred at 2 m depth, whilst maximum growth of thalli in the main culture area occured at 1.5 m depth. Production of E. stolonifera was between 3 and 9 kg wet wt. m⁻¹ in the first year of culture after seeding and 12 to 13 kg wet wt. m⁻¹ in the second year of culture, after management (depth control and fouling organism removal, etc.) of the holdfast. The relationship between optimal water depth for culture and underwater irradiance during the E. stolonifera cultivation was defined as: y = −0.331x + 8.198 (r ² = 0.9903). The growth rates achieved in this trial indicate that E. stolonifera cultures could produce sufficient biomass to supply summer feed for the Korean abalone industry.     

Biology of the bamboo Chusquea culeou (Poaceae: Bambusoideae) in southern Argentina

Over a period of 7 years the biology and phenotypic variability of Chusquea culeou were studied at 5 locations in cool temperate forests of southern Argentina. Excavated rhizomes had an average of 1.1 successful rhizome buds, and an average of 2.1 years elapsed between successive generations of rhizomes. Rhizome buds usually develop within the first four years after a rhizome forms. Height, volume and weight of a culm can be calculated from its diameter 1 m above the ground. Culm size, length of foliage leaf blades, and pattern of secondary branching differed among study sites. Dead culms were numerous and commonly remained erect for more than 7 years after dying. New culm shoots appear in spring and reach full size within a few months. Shoots can grow more than 9 cm/day. Less than half of the shoots survived a year; most were killed by moth larvae. Multiple primary branch buds emerge through the culm leaf sheaths in the second spring. The mean number of branch buds at mid-culm nodes varied between 34.8 and 81.5, and the mean number of primary branches was between 22.8 and 40.8. Number and length of branches, and number and length of foliage leaf blades at each node is related to the position of the node on a culm. Most branches grow about 3 cm and produce 1 to 3 foliage leaves annually. Foliage leaf blades generally live 2 years or more; few survive 6 years. Relative lengths of foliage leaf blades and their spacing along a branch permit recognition of annual cohorts.Both gregarious and sporadic flowering have been reported, and every year a few isolated plants flower and die. Length of the life cycle is unknown. Seedlings require up to 15 years to produce culms of mature size. Foliage branches may live more than 23 years, and culms may survive 33 years. Extensive loss of new shoots to predation suggests that gregarious flowering may be driven by a need to escape parasitism. C. culeou clumps expand slowly. Average annual rate of increase of the number of live culms in a clump was 4.6%. Methods of seed dispersal are undocumented. A dense stand of Chusquea culeou had an estimated phytomass of 179 tons/hectare (dry weight), 28% of which was underground. Net annual production was about 16 t/ha dry weight.     

Plant regeneration through somatic embryogenesis from tissues of mature oak trees: true-to-type conformity of plantlets by RAPD analysis

Somatic embryogenesis was induced in expanding leaf explants excised from epicormic shoots forced from branch segments taken at four different times of year from a mature oak (Quercus robur L.). Branch segments 2–4 cm in diameter produced most shoots when collected in March. Somatic embryos were induced on explants derived from branches of all collection dates, although collection in November seemed to afford the best results. Germination and conversion ability of embryos of embryogenic lines derived from six oak trees depended heavily on genotype, conversion rates ranging from 0 to 70%. RAPD analyses found no evidence of genetic variation either within or between the embryogenic lines established from three of these trees, or between these lines and the trees of origin, or between somatic embryo derived plantlets and the trees of origin. The embryogenic system used in this study appears to be suitable for true-to-type clonal propagation of mature oak genotypes.     

A molecular investigation of the genus Ecklonia (Phaeophyceae,Laminariales) with special focus on the Southern Hemisphere

Brown algae of the order Laminariales, commonly referred to as kelps, are the largest and most productive primary producers in the coastal inshore environment. The genus Ecklonia (Lessoniaceae, Phaeophyceae) consists of seven species with four species in the Northern Hemisphere and three in the Southern Hemisphere. It was recently transferred to the family Lessoniaceae based on phylogenetic analyses of nuclear and chloroplastic markers, though the type of the genus was not included and its relationship with allied genera Eckloniopsis and Eisenia remained unresolved. The present study is the first to produce a phylogeny focussed on the genus Ecklonia. It included sequences from nuclear, mitochondrial, and chloroplastic DNA, for most of the distribution range of the three current Southern Hemisphere species (Ecklonia radiata, Ecklonia maxima, and a sample of a putative Ecklonia brevipes specimen), sequences for East Asiatic species (Ecklonia cava, Ecklonia kurome, and Ecklonia stolonifera), as well as the closely related genera Eckloniopsis and Eisenia. Results confirmed E. radiata and E. maxima as two distinct species in South Africa, E. radiata as a single species throughout the Southern Hemisphere (in South Africa, Australia, and New Zealand) and East Asiatic species as a distinct lineage from the Southern Hemisphere clade. Results further pointed out a close sister relationship between Eckloniopsis radicosa and two Eisenia species (including the type species: Eisenia arborea) to the genus Ecklonia suggesting that the genera Eckloniopsis and Eisenia are superfluous.     

Growth of Ecklonia cava (Laminariales, Phaeophyta) sporophytes transplanted to a locality with different temperature conditions

Transplanting experiments were carried out to determine whether the small type sporophytes with short stipe of Ecklonia cava Kjellman (Laminariales, Phaeophyta) growing in a locality with warm temperatures, change into larger type with a long stipe when transplanted to a locality with cooler temperatures. Juvenile E. cava sporophytes, having a stipe shorter than 5 cm long were collected from Tei in Tosa Bay (southern Japan) (seawater temperature 15–29°C) and transplanted to Nabeta Bay (central Japan) (seawater temperature 13–25°C), where larger type E. cava sporophytes characterized by long stipe (ca 1 m) grow. They were attached to artificial reefs at the sea bottom (9 m depth) in Nabeta Bay to monitor their growth. For comparison, juvenile E. cava sporophytes of almost similar size growing in Nabeta Bay were also transplanted in the same way to the same experimental site. Observations of growth of sporophytes from Tei and Nabeta were carried out monthly for 2 years from November 1995 to October 1997. The transplanted Tei and Nabeta sporophytes showed an increase in stipe length and diameter from winter to spring, whereas almost no increase was observed during summer and autumn. At the end of the study period, the stipe of Nabeta sporophytes reached 25.6 cm in length and 17.0 mm in diameter, whereas that of Tei sporophytes reached 11.1 cm in length and 11.2 mm in diameter. The primary blade length was 16.0 cm in Nabeta sporophytes, whereas it was 5.5 cm in Tei sporophytes. Thus, Tei sporophytes still remained smaller than Nabeta sporophytes even under the same environmental conditions.     

The macrofaunal community of Ecklonia radiata holdfasts: Variation associated with sediment regime,sponge cover and depth

Abstract The relationship among the Ecklonia radiata holdfast macrofaunal community, sediment content and sponge cover was evaluated for data collected over a four year period at Coffs Harbour, mid-north coast, New South Wales. While several taxa demonstrated significant relationships with these factors, the correlations explained a maximum of 24% of the variation in the data and explanatory power was consequently low. Differences in the composition of the holdfast community were also evaluated at two depths (2m and 6m) at two sites in a mensurative field experiment conducted in summer and winter 1991. The results of both ANOVA and non-parametric multivariate statistical analyses (MDS, ANOSIM, SIMPER) indicated that there were consistent, significant differences between depths over the two sample times. Although some common species demonstrated significant associations with one depth, small differences in the abundance of a large number of species were primarily responsible for the overall differences in community structure between depths. Sediment content and holdfast age were both significantly greater in samples collected from 6 m which may account for some of the depth-related faunistic differences. However, the overall differences between depths are probably related to unmeasured factors such as turbulence due to wave action and holdfast morphology which covary with depth. The results highlight the enormous variability associated with the Ecklonia radiata holdfast macrofaunal community and the consequent necessity to consider as many factors as possible in comparative studies of community structure.     

Morphometric study of Ecklonia cava (Laminariales, Phaeophyta) sporophytes in two localities with different temperature conditions

Sporophytes of Ecklonia cava Kjellman (Laminariales, Phaeophyta) were collected seasonally from within 3–4 replicate, 1‐m² quadrates, haphazardly placed in dense assemblages at 6–9 m depth in Tei, Tosa Bay (southern Japan; water temperature 15–29°C) from 1995 to 1996, and in Nabeta Bay, Shimoda (central Japan; water temperature 13–25°C) from 1996 to 1997. Growth rings were checked for all samples and mean values of each biometric parameter of sporophytes 1‐year‐old and over were compared. The plant length (stipe length + primary blade length) was always shorter in Tei sporophytes (24–52 cm) than Nabeta sporophytes (70–100 cm), the difference being mainly owing to the shorter stipe length in Tei sporophytes (7–14 cm) than in Nabeta sporophytes (54–83 cm). However, the primary blade length was sometimes longer in Tei sporophytes (12–38 cm) than in Nabeta sporophytes (14–21 cm). Stipe diameter, longest bladelet length and primary blade width were mostly less in Tei sporophytes (8.6–12.4 mm, 5.5–7.0 cm and 23.4–38.0 cm, respectively) than Nabeta sporophytes (16.4–20.2 mm, 9.2–12.0 cm and 43.0–52.6 cm, respectively). Nevertheless, the number of bladelets of sporophytes from Tei (15–28) and Nabeta (18–29) were within the same range. At Tei, 32–43% of the sporophytes had wrinkled blades in summer and autumn, whereas wrinkled primary blades or bladelets were not observed in Nabeta sporophytes throughout the experimental period. These morphometric differences of E. cava between the two localities are suggested to be dependent on environmental factors, especially seawater temperature.     

Effects of NaCl and Na2SO4 on red-osier dogwood (Cornus stolonifera Michx) seedlings

Sodium chloride and sodium sulfate are commonly present in extraction tailings waters produced as a result of surface mining and affect plants on reclaimed areas. Red-osier dogwood (Cornus stolonifera Michx) seedlings were demonstrated to be relatively resistant to these high salinity oil sands tailings waters. The objectives of this study were to compare the effects of Na₂SO₄ and NaCl, on growth, tissue ion content, water relations and gas exchange in red-osier dogwood (Cornus stolonifera Michx) seedlings. In the present study, red-osier dogwood seedlings were grown in aerated half-strength modified Hoagland's mineral solution containing 0, 25, 50 or 100 mM of NaCl or Na₂SO₄. After four weeks of treatment, plant dry weights decreased and the amount of Na⁺ in plant tissues increased with increasing salt concentration. Na⁺ tissue content was higher in plants treated with NaCl than Na₂SO₄ and it was greater in roots than shoots. However, Cl^– concentration in the NaCl treated plants was higher in shoots than in roots. The decrease in stomatal conductance and photosynthetic rates observed in presence of salts is likely to contribute to the growth reduction. Our results suggest that red-osier dogwood is able to control the transport of Na⁺ from roots to shoots when external concentrations are 50 mM or less.     

<Emphasis Type="Italic">In vitro</Emphasis> propagation of an endangered plant species, <Emphasis Type="Italic">Thermopsis turcica</Emphasis> (Fabaceae)

This report deals with micropropagation of the critically endangered and endemic Turkish shrub, Thermopsis turcica using callus, root and cotyledonary explants. Callus cultures were initiated from root and cotyledon explants on MS medium supplemented with 0.5–20 μM NAA or 2,4-D. The root explants were found to be better in terms of quick responding and callusing percentages as compared to the cotyledons. Organogenic callus production with adventitious roots and shoots were obtained on MS medium with only NAA. The calli obtained with NAA, root and cotyledonary explants were cultured with BA and kinetin (2–8 μM) alone or in combination with a low level (0.5 μM) of 2,4-D or NAA. The best regeneration of shoots from root explants was observed on hormone-free MS medium. NAA with BA or kinetin in the medium improved shoot induction from the calli obtained with NAA. Maximum percentage of shoots (93.3%), maximum number of shoots (6.2) and maximun length of shoots (8.22 cm) were achieved from cotyledonary explants at 4 μM BA and 0.5 μM NAA. The presence of 0.5 μM or higher levels of 2,4-D in shoot induction medium inhibited the regeneration in T. turcica explants. 83% of in vitro rooting was attained on pulsed-IBA treated shoots. The regenerated plants with well developed shoots and roots were successfully acclimatized. Application of this study’s results has the potential to conserve T. turcica from extinction.     

Ecomorphology ofCrassostrea cucullata (Born, 1778) (Ostreidae) in a mangrove creek (Gazi,Kenya)

Variations of shell form and shell length were studied for oysters growing in the mangroves of Gazi Creek, Kenya, and related to different environmental factors.For the study of the form, Fourier analysis was performed on the circumference of 85 oysters. The resulting coefficients were compared among specimens using cluster analysis. The correspondence between this classification and substrate diameter is virtually perfect (only one misclassification out of 85 oysters). For the clusters based on height above chart datum, 9 specimens, all on intermediate height levels, were misclassified. Orientation with respect to tidal current had 13 misclassifications. Mangrove species seemed to influence form only marginally, if at all.In the study of the size ofCrassostrea cucullata, the length of 956 oysters, growing along two transects were measured, and correlated with several environmental factors. Oyster length was not related to substrate diameter or its orientation with respect to the main current. Length was not influenced by density up to a cover of 70%. For densities higher than 70%, there was a fairly strong negative correlation (r ² = 0.634,n = 217). Length was not correlated with height above bottom (base of the tree) for heights lower than 20 cm, while oysters growing closer to the bottom were smaller. The correlation with height above chart datum was negative but very low (r ² = 0.060,n = 957). However, if all measurements of oysters closer than 20 cm to the bottom, and all from a density of more than 70% cover are deleted from the data set, the correlation with height increased dramatically, the slope still being negative (r ² = 0.859,n = 543).     

Adventitious shoot formation in cultures of 30-year-old Larix decidua,L. leptolepis,L. eurolepis,and L. laricina trees

Primordial shoot explants excised from buds of one Larix decidua tree, about 30 years old, produced more adventitious buds, elongating into shoots, when grown on half strength Litvay medium than when grown on other basal media. Thidiazuron and N₆-benzyladenine (BA) were equally effective in adventitious bud induction. In a comparative study of 30-year-old L. decidua, L. leptolepis, L. eurolepis, and L. laricina trees, explants from L. eurolepis and L. decidua produced a high number of cultures with adventitious buds that elongated into shoots; those from L. leptolepis were less productive, and those from L. laricina failed to form adventitious buds. The highest response was obtained with material collected in August and September, and in March and April; the lowest response occurred in explants from the October collection.     

Age, Growth Rates, Sex Change and Feeding Habits of Notothenioid Fish Eleginops Maclovinus from the Central-southern Chilean Coast

The róbalo, Eleginops maclovinus, a protandrous hermaphrodite species, is an important component of the ichthyofauna in the coastal areas and estuaries of southern Chile. However, there are many aspects about its life history that are unknown. Three hundred and eighty-three specimens of E. maclovinus (19–79 cm total length, TL) were collected between November 2002 and December 2003 from central-southern Chile. Marginal increment analysis from sagittal otoliths showed a single annual minimum in March, demonstrating that a single growth ring is formed each year. The growth of E. maclovinus was described by the von Bertalanffy growth model by following parameters: L _∞ = 105.4 cm TL, K = 0.08 per year, and t ₀ = −1.03 years. E. maclovinus can live for 10 years. The length and age at which the 50% of the males in the population transformed into females was estimated at ~36 cm TL and ~5-years old. A total of 27 prey items were identified. The most important prey items were the crustaceans Hemigrapsus crenulatus and Emerita analoga associated with estuarial and marine habitats respectively. Ontogenetic changes in the diet were related to the spatial distributional pattern of males (1–4 years old, in the estuary) and females (5–8 years old, in the sea). Also, diet changes are associated with the type of available prey in each habitat occupied, indicating a generalized opportunist strategy.     

A rapid in vitro propagation protocol for Piper barberi Gamble, a critically endangered plant

Summary A protocol is described for rapid multiplication of Piper barberi Gamble (Piperaceae) through shoot tip and nodal explant cultures. Nodal explants with a single axillary meristem showed three times better response with respect to shoot proliferation when compared to shoot tip explants. The best shoot proliferation response of nodal explants was observed with a cytokinin combination of N₆-benzyladenine (4.43 μM) and kinetin (2.32 μM), with 88% bud break. The number of shoot initials (2.4) produced per nodal explant was twice the number of shoot initials (1.2) per shoot tip. An average of 6.9±0.58 adventitious shoots were observed from the proximal end of the internodal explants on Mursashige and Skoog (1962) (Ms) basal medium supplemented with N₆-benzyladenine (2.22 μM) and kinetin (0.46 μM). A multiplication rate of 82 shoots per explant could be achieved after 9 wk of subculturing. The in vitro shoots were rooted on one-half and one-quarter MS basal medium. The shoots rooted on one-quarter MS in the dark produced eight roots with an average root length of 3.36 cm and 98% survival. These plants were transferred to the field with a survival rate of 75%.     

Micropropagation ofDalbergia sissoo from nodal explants of mature trees

A method for micropropagation ofDalbergia sissoo has been developed. Single node segments obtained from coppice shoots of a mature tree (20 – 25 year old) produced 3–4 shoots per explant on Murashige and Skoog (MS) medium containing 4.4 x 10⁻⁶ M benzylaminopurine (BAP) and 4.4 × 10⁻⁷ M of Β-naphthoxy acetic acid (NOA) (shoot multiplication medium) within 4 weeks. Thein vitro regenerated shoots were 3 – 4 cm in length and provided 2 to 3 culturable nodal segments which on shoot multiplication medium again produced 3–4 shoots. Following this procedure 18–24 shoots were produced from single nodal segment within 60 d. 80 % of the shoots directly produced five roots when they were firstly treated with MS medium supplemented with 10⁻⁵ M indole-3-butyric acid (IBA) and subsequently transferred to half strength liquid MS medium containing 1 % activated charcoal followed by half strength liquid MS free hormones, vitamins and activated charcoal. Thein vitro raised plants were hardened for survival after transplantation to soil by exposing them to various humidity conditions, gradually from higher to low, with nearly 100 % transplant success. Acknowledgement: Authors are grateful to CSIR and DST, New Delhi for financial assistance.     

Vegetative propagation of adult Eucalyptus grandis X urophylla and comparison of growth between micropropagated plantlets and rooted cuttings

Methods for the production of micropropagated plantlets and rooted cuttings were developed and used to vegetatively multiply adult Eucalyptus grandis X urophylla. Rooting success was less than 5% when cuttings excised from twigs of 3-year-old trees were used. The rooted cuttings were grown in the greenhouse as explant- or cutting-donors and maintained at a height of 30 to 100 cm by trimming back periodically. Good rooting success (95%) of cuttings was obtained for epicormic shoots produced from donor plants after trimming 5 times. Explants of both apical and axillary buds taken from the donor plants produced multiple shoots when cultured in vitro. In vitro multiple shoot production was optimal on MS medium containing 0.1 mg/l BA and 0.01 mg/l NAA averaging 13.7 shoots per explant in a 40-day culture period. Shoot elongation was accelerated on a modified MS medium containing half strength potassium nitrate and sucrose. Elongated shoots excised at approximately 1.5 cm in length were successfully rooted on media with NAA or IBA concentrations ranging from 0.1 to 10 mg/l. Root formation was optimal on medium consisting of full strength MS basal macro elements and vitamins, half strength micro elements, 1% sucrose and supplemented with 0.3 mg/l IBA. In the field test, no significant differences were found in tree height and DBH between micropropagated plantlets and rooted cuttings at 1 and 3 years old, with the exception at 2 years old. A considerable difference arose between the 2 types of vegetative propagules in physiological response to flowering, caused by dissimilar degrees of rejuvenation.Abbreviations BA Benzyl-Aminopurine - NAA Naphthalene Acetic Acid - IBA Indole-3-Butyric Acid - MS medium Murashige and Skoog's medium - DBH Diameter at Breast Height     

Nonlinear multivariate models of successional change in community structure using the von Bertalanffy curve

von Bertalanffy curves were used to describe the nonlinear relationship between assemblages inhabiting holdfasts of the kelp Ecklonia radiata and the volume of the holdfast. This was done using nonlinear canonical analyses of principal coordinates (NCAP). The volume of the holdfast is a proxy for the age of the plant and, thus, the canonical axis is a proxy for succession in the marine invertebrate community inhabiting the holdfast. Analyses were done at several different taxonomic resolutions on the basis of various dissimilarity measures. Assemblages in relatively large holdfasts demonstrated ongoing variation in community structure with increasing volume when the dissimilarity used was independent of sample size. Smaller holdfasts had proportionately greater abundances of ophiuroids and encrusting organisms (bryozoans, sponges, ascidians), while larger holdfasts were characterised by proportionately greater abundances of crustaceans, polychaetes and molluscs. Such linear and nonlinear multivariate models may be applied to analyse system-level responses to the growth of many habitat-forming organisms, such as sponges, coral reefs, coralline algal turf or forest canopies.