Bioerosion rates of the sponge Cliona orientalis Thiele, 1900: spatial variation over short distances

We studied bioerosion rates and tissue growth of the sponge Cliona orientalis Thiele, 1900. Experimental blocks grafted with sponge tissue were deployed at three sites in Moreton Bay, QLD, Australia, which have different environmental conditions. Bioerosion rates varied between 4, 5, and 10 kg m⁻² year⁻¹ when related to final tissue area and between 4, 7, and 16 kg m⁻² year⁻¹ when related to initial tissue area of the graft, which supports findings of earlier studies. Comparing results between the sites, eutrophication appeared to have the most stimulating effect and is most likely to have caused the measured differences. However, slight differences between shading and current speeds may also have played a role. Variation may have masked spatial differences of sponge growth, which were insignificant between study sites. Growth and bioerosion nevertheless followed the same trend and were weakly correlated. Habitat quality itself had no influence. Overall, the twofold difference in sponge bioerosion over a distance as short as 10 km suggests that when estimating bioerosion rates, subsamples should be tested at different locations.     

Age and productivity of the Antarctic scallop, Adamussium colbecki, in Terra Nova Bay (Ross Sea, Antarctica)

Body size, geographical distribution, and biomass make Adamussium colbecki (Smith, 1902) one of the most conspicuous bivalve species in the Antarctic. Based on samples collected in austral summer 1999/2000 in Terra Nova Bay, the annual formation of shell growth bands visible on X-ray photographs was verified by stable isotope analysis. A general von Bertalanffy growth function was fitted to size-at-age data of 25 individuals (H_∞=108.86 mm, K=0.114 year⁻¹, t₀=−0.367, D=1.284). Somatic production calculated from mass-specific growth rates was 234.6 kJ m⁻² year⁻¹. Gonadal productivity amounted to 70.92 kJ m⁻² year⁻¹. Annual somatic and gonad production-to-biomass ratios (P/B) were 0.199 and 0.052, respectively. According to its consumption and production, A. colbecki is likely to play a significant role in the trophic web of Terra Nova Bay.     

Recruitment,mortality and growth of mangrove (<Emphasis Type="Italic">Rhizophora</Emphasis> sp.) seedlings in Ulugan Bay,Palawan, Philippines

Propagule dispersal, establishment and recruitment to the sapling stage are critical steps in the life cycle of mangroves. Specific (i.e., per capita) rates of recruitment and mortality, and the growth rates of Rhizophora seedlings in three mangrove stands in Ulugan Bay (Palawan, Philippines) were estimated between March 1999 and February 2001. Recruitment and mortality were variable in space and time, with mortality exceeding rates of recruitment at all sites. The specific rates of seedling recruitment and mortality were higher in Buenavista (0.66 year^–1 and –1.67 year^–1) than in Umalagan (0.05 year^–1 and –0.33 year^–1) and Oyster Bay (0.13 year^–1 and –0.24 year^–1). The annual rate of production of internodes by the main stem was similar at the three sites (5.4–5.5 internodes year^–1), but the annual rate of elongation of the main stem was higher in Buenavista (10.6 cm year^–1) than in Oyster Bay (7.6 cm year^–1) and Umalagan (5.6 cm year^–1).     

Grazing-induced morphological and growth rate changes in Anarthrophyllum rigidum,a Patagonian leguminous shrub

Grazing influences the morphology and growth rate of shrubs, and consequently, their population dynamics. It has been shown that grazing directly affects the growth of shrubs. On the other hand, the reduction of grass biomass by herbivores reduces soil–water competition between grasses and shrubs, and indirectly, could enhance the growth of shrubs. However, the assessment of the long-term effects of grazing on the growth of shrubs in the arid Patagonia has been hampered by the lack of long and homogeneous records of plant population dynamics and primary production. In this study, we combined growth-ring and allometric analyses to assess the long-term effect of grazing on individuals of Anarthrophyllum rigidum, a leguminous shrub widely distributed across the Patagonian steppe. A. rigidum has evergreen leaves rich in proteins that constitute an important complement to the diet of sheep, particularly in winter when the abundance of grasses is reduced. Our observations indicate that individuals of A. rigidum nearby the water source used by livestock were smaller in size (35.5 cm vs. 67.39 cm), presented a larger number of basal branches (23 vs. 12), and showed slower rates of growth (8.2 mm year^?1 vs. 14.3 mm year^?1) than individuals located far from the water source. This first quantification of the long-term effects of grazing on A. rigidum in the dry Patagonian steppe suggests that beneficial effects of grazing through the reduction of grasses that compete with shrubs for soil–water should be more obvious for livestock non-preferred than preferred shrubs     

Marine-Based Cultivation of <Emphasis Type="Italic">Diacarnus</Emphasis> Sponges and the Bacterial Community Composition of Wild and Maricultured Sponges and Their Larvae

Marine organisms including sponges (Porifera) contain many structurally diverse bioactive compounds, frequently in a low concentration that hampers their commercial production. Two solutions to this problem are: culturing sponge explants for harvesting the desired compound and cultivation of sponge-associated bacteria. These bacteria (often considered the source of the desired compounds) include the Actinobacteria, from which many novel drugs were developed. In a long-term experiment (lasting 767 days), we evaluated the culture amenability of the sponge Diacarnus erythraenus in a mariculture system, placed at 10- and 20-m depths. The growth and survival rates of sponge fragments were monitored. Wild and maricultured sponges from both depths and their larvae were sampled at different time intervals for denaturing gradient gel electrophoresis (DGGE) profiling of the bacterial community residing within them. 16S rRNA gene sequences of both cultured bacterial isolates and clone libraries of unculturable bacteria were composed and compared, focusing on Actinobacteria. Sponges from both depths did not differ significantly either in mean growth rates (percent weight change year⁻¹ ± S.E.) (64.5% ± 21% at 10 m and 79.3% ± 19.1% at 20 m) or in seasonal growth rates. Survival was also very similar (72% at 10 m and 70% at 20 m). There were 88 isolates identified from adults and 40 from their larvae. The isolates and clone libraries showed diverse bacterial communities. The DGGE profiles of wild and maricultured sponges differed only slightly, without a significant effect of depths or dates of sampling. This long-term experiment suggests that D. erythraenus probably remained healthy and indicates its mariculture suitability.     

Relative importance of bacteria, microalgae and yeast for growth of the sponge Halichondria melanadocia (De Laubenfels, 1936): A laboratory study

Bacteria, microalgae and yeast less than 10 μm in size are the primary food source of sponges but their relative contribution to somatic growth is poorly understood. In a laboratory study, the sponge Halichondria melanadocia was fed for 6 weeks a diet consisting solely of four bacterial strains, or a mixed diet consisting of bacteria, microalgae and yeast. Both diets were fed at three concentrations, based on the natural concentration (NC) of particles available to sponges: 1/5, 1 and 5NC. Mean final size of H. melanadocia was 40% greater on a mixed diet than on the bacteria diet, probably because of the greater supply of carbon and other essential nutrients in microalgae and yeast. Cell concentration also significantly affected the growth of H. melanadocia, with greatest growth for sponges fed at the highest cell concentration. The estimated carbon requirement for H. melanadocia to meet metabolic costs was 0.356 mg C l^− 1 or 103 μg C h^− 1 gDW^− 1. Many H. melanadocia appeared to be optimizing their surface area for food uptake.     

Variation in reproductive output of marine turtles

Most marine turtle species are non-annual breeders and show variation in both the number of eggs laid per clutch and the number of clutches laid in a season. Large levels of inter-annual variation in the number of nesting females have been well documented in green turtle nesting populations and may be linked to environmental conditions. Other species of marine turtle exhibit less variation in nesting numbers. This inter-specific difference is thought to be linked to trophic status. To examine whether individual reproductive output is more variable in the herbivorous green turtle (Chelonia mydas Linneaeus 1758) than the carnivorous loggerhead (Caretta caretta Linneaeus 1758), we examined the nesting of both species in Cyprus over nine seasons. Green turtles showed slower annual growth rates (0.11 cm year⁻¹ curved carapace length (CCL) and 0.27 cm year⁻¹ curved carapace width (CCW)) than loggerhead turtles (0.36 cm year⁻¹ CCL, 0.51 cm year⁻¹ CCW). CCL was highly correlated to mean clutch size in both green (R²=0.51) and loggerhead turtles (R²=0.61) and maximal clutch size of green turtles (R²=0.58). Larger females did not lay a greater number of clutches or have a shorter remigration interval than smaller females of either species. On average, the size of green turtle clutches increased and that of loggerhead turtles decreased as the season progressed. Individual green turtles, however, produced more eggs per clutch through the season to a maximum in the third or fourth clutch. In loggerhead turtles, clutches 1-4 were very similar in size but the fifth clutch was 38% smaller than the first. No individuals of either species were recorded laying more than five clutches. Green turtles may not be able to achieve their maximum reproductive output with respect to clutch size throughout the season, whereas only loggerhead turtles laying five clutches (n=5) appear to become resource depleted. Green turtles nesting in years when large numbers of nests were recorded laid a greater number of clutches than females nesting in years with lower levels of nesting.     

Growth and regeneration of the elephant ear sponge Ianthella basta (Porifera)

Sponges are an important component of the benthic community, especially on coral reefs, but demographic data such as growth, recruitment or mortality are notably limited. This study examined the growth of the elephant ear sponge Ianthella basta, the largest and in some areas one of the dominating sponge species on Guam and other pacific reefs. We measured growth rates of the natural population on Guam over the course of one year and identified intra-individual growth patterns. Initial sponge sizes ranged from 200 to 35,000 cm². Specific growth rates ranged from 0.08 to 6.08 with a mean specific growth rate of 1.43 ± 1.29 (SD) year⁻¹. Furthermore, specific growth decreased with sponge size. The age estimate for the largest sponge (1.7 m height × 9.5 m circumference) was ~8 years. Intra-individual growth was mostly apical. This study demonstrated high growth rates, which has notable implications for environmental assessments, management and potential biomedical applications.     

Pilot trophic model for subantarctic water over the Southern Plateau, New Zealand: a low biomass, high transfer efficiency system

The Southern Plateau subantarctic region, southeast of New Zealand, is an important feeding area for birds, seals and fish, and a fishing ground for commercially significant species. The Southern Plateau is a major morphometric feature, covering approximately 433,620 km² with average depth of 615 m. The region is noted for its relatively low levels of phytoplankton biomass and primary production that is iron-limited. In order to evaluate the implications of these attributes for the functioning of this ecosystem a steady-state, 19-compartment model was constructed using Ecopath with Ecosim software of Christensen et al. [www.ecopath.org]. The system is driven by primary production that is primarily governed by the supply of iron and light. The total system biomass of 6.28 g C m⁻² is very low compared with systems so far modelled with a total system throughput of 1136 g C m⁻² year⁻¹. In the model, the Southern Plateau retains 69% of the biomass in the pelagic system and 99% of total production. Although fish are caught demersally, most of their food is part of production in the pelagic system. Top predators represent about 0.3% of total biomass and account for about 0.24 g C m⁻² year⁻¹ of food consumed made up of birds 0.058 g C m⁻² year⁻¹, seals 0.041 g C m⁻² year⁻¹, and toothed 0.094 g C m⁻² year⁻¹ and baleen whales 0.051 g C m⁻² year⁻¹. This amounts to 105,803 tonnes carbon over the whole of the Southern Plateau and is about 17% of the total amount of food eaten by non-mesopelagic fish. Mean transfer efficiencies between trophic levels II and IV of 23% are at the high end of the range reported in the literature. In the model, adult fish production is almost completely accounted for by the fisheries take (32%), consumption by seals (7%), toothed whales (21%), other adult fish (13%), and squid (20%). Fish and squid catches are at the trophic levels of 4.8 and 5.0, respectively. The gross efficiency of the fishery is 0.018% (catch/primary production). Although not all data come from direct knowledge of this system, the model reflects its general characteristics, namely a low primary production system dominated by the microbial loop, low sedimentation to the seafloor, high transfer efficiencies, a long food web and supporting high-level predators.     

Development of In Vivo Sponge Cultures: Particle Feeding by the Tropical Sponge Pseudosuberites aff. andrewsi

The rate of food particle uptake of the tropical sponge Pseudosuberites aff. andrewsi was studied in relation to particle concentrations and particle size. A range of different concentrations of either the marine microalga Dunaliella tertiolecta (∼5–8 μm) or the marine cyanobacterium Synechococcus sp. (∼1 μm) was supplied to the sponges. D. tertiolecta had a pronounced effect on the filtration activity of the sponges: at concentrations higher than approximately 4 × 10⁵ cells/cm³, the filtration rates dropped dramatically. Such a clear effect was not found for Synechococcus sp. The results further showed that the maximal amount of food (when expressed in organic carbon) that can be taken up per cubic centimeter of sponge volume per unit of time should in principle be sufficient to enable growth (irrespective of the food particle type). At the maximal food particle concentration that did not affect the filtration rates, the uptake of organic carbon is already highly in excess of the amount of organic carbon that the sponges need to cope with their respiratory demand. Based on these findings, a series of growth experiments was carried out in which the sponges were subjected to a constant concentration of different types of food particles (Synechococcus sp. and the microalgae Chlorella sorokiniana and Nannochloropsis sp). Although initial growth was sometimes observed, continuous growth at a constant rate could not be obtained. It is concluded that qualitative aspects of feeding rather than quantitative aspects are the key to successful in vivo sponge culture. Received December 20, 2000; accepted March 26, 2001     

Sponge communities from the Lower Liassic of Adnet (Northern Calcareous Alps, Austria)

The lower slope of the drowned Alpine Adnet Reef was recolonized in Hettangian time by sponge communities of hexactinellid (hexactinosid and lyssacinosid) taxa and a few demosponges. Special taphonomic processes caused an excellent preservation of these sponges. The preservation allows to define several growth forms and to study original spicule configurations of the mainly non-rigid skeletons. Sponge faunas of presumably similar associations are known from adjacent basins, but only by isolated spicules of completely collapsed specimens. In Adnet the sponges are embedded in biodetrital limestones of the Schnöll Formation. Orientation and distribution of the sponges reflect autochthonous faunas that have been mixed with dislocated individuals by local water currents. The predominance of erect sponge types indicates intermediate sedimentation rates and/or occasional high-energy events. Sponge types and community structures are comparable with those ones from Middle Paleozoic mud mounds. Several hiatuses, mostly characterized by ferromanganese crusts have been kept free of sponge settlement. Carbon stable isotopes of the sponge-rich sequence show a small negative δ¹³C_carb excursion that covers the period from Lower Hettangian to Lower Sinemurian.This revised version was published online in May 2005 because several displayed passages had been inadvertently deleted in the original published version.     

Integrated stream and wetland restoration: A watershed approach to improved water quality on the landscape

Water quality in Upper Sandy Creek, a headwater stream for the Cape Fear River in the North Carolina Piedmont, is impaired due to high N and P concentrations, sediment load, and coliform bacteria. The creek and floodplain ecosystem had become dysfunctional due to the effects of altered storm water delivery following urban watershed development where the impervious surface reached nearly 30% in some sub-watersheds. At Duke University, an 8-ha Stream and Wetland Assessment Management Park (SWAMP) was created in the lower portion of the watershed to assess the cumulative effect of restoring multiple portions of stream and former adjacent wetlands, with specific goals of quantifying water quality improvements. To accomplish these goals, a three-phase stream/riparian floodplain restoration (600 m), storm water reservoir/wetland complex (1.6 ha) along with a surface flow treatment wetland (0.5 ha) was ecologically designed to increase the stream wetland connection, and restore groundwater wetland hydrology. The multi-phased restoration of Sandy Creek and adjacent wetlands resulted in functioning riparian hydrology, which reduced downstream water pulses, nutrients, coliform bacteria, sediment, and stream erosion. Storm water event nutrient budgets indicated a substantial attenuation of N and P within the SWAMP project. Most notably, (NO₂⁻ + NO₃⁻)-N loads were reduced by 64% and P loads were reduced by 28%. Sediment retention in the stormwater reservoir and riparian wetlands showed accretion rates of 1.8 cm year⁻¹ and 1.1 cm year⁻¹, respectively. Sediment retention totaled nearly 500 MT year⁻¹.     

Patch dynamics of the Mediterranean seagrass Posidonia oceanica: Implications for recolonisation process

Patch dynamics of the Mediterranean slow-growing seagrass Posidonia oceanica was studied in two shallow sites (3–10 m) of the Balearic Archipelago (Spain) through repeated censuses (1–2 year⁻¹). In the sheltered site of Es Port Bay (Cabrera Island), initial patch density (October 2001) was low: 0.05 patches m⁻², and the patch size (number of shoots) distribution was bimodal: most of the patches had less than 6 shoots or between 20 and 50 shoots. Mean patch recruitment in Es Port Bay (0.006 ± 0.002 patches m⁻² year⁻¹) exceeded mean patch loss (0.001 ± 0.001 patches m⁻² year⁻¹), yielding positive net patch recruitment (0.004 ± 0.003 patches m⁻² year⁻¹) and a slightly increased patch density 3 years later (July 2004, 0.06 patches m⁻²). In the exposed site of S’Estanyol, the initial patch density was higher (1.38 patches m⁻², August 2003), and patch size frequency decreased exponentially with size. Patch recruitment (0.26 patches m⁻² year⁻¹) and loss (0.24 patches m⁻² year⁻¹) were high, yielding a slightly increased patch density in the area 1 year later (October 2004, 1.40 patches m⁻²). Most recruited patches consisted of rooting vegetative fragments of 1–2 shoots. Seedling recruitment was observed in Summer 2004 at both sites. Episodic, seedling recruitment comprised 30% and 25% of total patch recruitment in Es Port Bay and S’Estanyol, respectively. Patch survival increased with patch size and no direct removal was observed among patches of 5 shoots or more. Most patches grew along the study, shifting patch distribution towards larger sizes. Within the size range studied (1–150 shoots), absolute shoot recruitment (shoots year⁻¹) increased linearly with patch size (R² = 0.64, p < 4 × 10⁻⁵, N = 125), while specific shoot recruitment was constant (about 0.25 ± 0.05 year⁻¹), although its variance was large for small patches. Given the slow growth rate and the high survival of patches with 5 or more shoots, even the low patch recruitment rates reported here could play a significant role in the colonisation process of P. oceanica.     

Assessment of the relative contribution of asexual propagation in a population of the coral-excavating sponge Cliona delitrix from the Bahamas

Cliona delitrix is a very destructive coral-excavating sponge in Caribbean coral reef systems, particularly for Montastraea species. Little is known about how these excavating sponges propagate across coral reefs. In this study a hypothesis was tested that coral breakage caused by the bioeroding activity facilitates the asexual propagation of this sponge and in turn favors the spread of the most aggressive sponge genotypes. An allozyme analysis, involving 12 loci systems of 52 sponge individuals from a total of 13 Montastraea heads, found that no two sponges possessed identical multi-locus genotypes. Contrary to the pattern expected for fragmenting species, the incidence of clonality and asexual propagation at the population level was minimal. The lack of correlation between genetic and physical distances for the studied sponges also suggests that population maintenance appears to derive from larval dispersal, with a spatial range of dispersal larger than the average distance between the coral heads (10–10² m).     

Effects of soil structural discontinuity on root and shoot growth and water use of maize

The role of roots penetrating various undisturbed soil horizons beneath loose layer in water use and shoot growth of maize was evaluated in greenhouse experiment. 18 undisturbed soil columns 20 cm in diameter and 20 cm in height were taken from the depths 30–50 cm and 50–70 cm from a Brown Lowland soil, a Pseudogley and a Brown Andosol (3 columns from each depth and soil). Initial resistance to penetration in undisturbed soil horizons varied from 2.5 to 8.9 MPa while that in the loose layer was 0.01 MPa. The undisturbed horizons had a major effect on vertical arrangement of roots. Root length density in loose layer varied from 96 to 126 km m^-3 while in adjacent stronger top layers of undisturbed horizons from 1.6 to 20.0 km m^-3 with higher values in upper horizons of each soil. For specific root length, the corresponding ranges were 79.4–107.7 m g^-1 (on dry basis) and 38.2–63.7 m g^-1, respectively. Ratios of root dry weight per unit volume of soil between loose and adjacent undisturbed layers were much lower than those of root length density indicating that roots in undisturbed horizons were produced with considerably higher partition of assimilates. Root size in undisturbed horizons relative to total roots was from 1.1 to 38.1% while water use from the horizons was from 54.1 to 74.0%. Total water use and shoot growth were positively correlated with root length in undisturbed soil horizons. There was no correlation between shoot growth and water use from the loose layers.     

Size frequency,dispersal distances and variable growth rates of young sharks in a multi-species aggregation

During a mark–recapture survey from November 2014 until April 2017, 333 neonatal and juvenile blacktip reef sharks Carcharhinus melanopterus and 302 neonatal and juvenile sicklefin lemon sharks Negaprion acutidens were tagged and measured at the uninhabited and isolated St. Joseph Atoll (Republic of Seychelles). Both species demonstrated seasonal reproductive synchronicity and relatively large sizes at birth. Despite the extended times at liberty > 2.5 years, the majority of recaptures were found in close proximity to the initial tagging location (< 500 m). Annual growth rates of C. melanopterus (n = 24) and N. acutidens (n = 62) ranged from 6.6 to 31.7 cm year⁻¹ (mean ± SE; 16.2 ± 1.2 cm year⁻¹) and 0.2 to 32.2 cm year⁻¹ (11.8 ± 1 cm year⁻¹), respectively and are to date the most variable ever recorded in wild juvenile sharks. High abundances of both species coupled with long-term and repeated recaptures are indicative of a habitat where juveniles can reside for their first years of life. However, large variability in annual growth rates in both species may suggest high intra and interspecific competition induced by a possibly resource limited, isolated habitat.     

Comparison of maize,permanent cup plant and a perennial grass mixture with regard to soil and water protection

Agricultural production of biogas maize (Zea mays L.) causes hazards to aquatic ecosystems through high levels of nitrogen (N) inputs. Newly introduced and already established perennial crops such as the cup plant (Silphium perfoliatum L.) and perennial grass mixtures offer the possibility of more environmentally friendly agricultural bioenergy production. The objectives of this field study were to quantify and compare soil mineral N, water infiltration, water runoff, soil erosion and N leaching under maize, permanent cup plant, and a perennial grass mixture. The study was conducted from October 2016 to March 2019 in Braunschweig, Germany. Plots with cup plant and grass mixture exhibited lower mineral N contents than maize, especially between 30 and 90 cm soil depth. Soil water infiltration was significantly different between the three crops. The grass mixture had the highest infiltration rates (6.2 mm/min averaged across 3 years), followed by cup plant (3.6 mm/min) and maize (0.9 mm/min). During wet periods, higher N leaching was found for maize (up to 42 kg N ha^?1 year^?1) than for cup plant (up to 5 kg N ha^?1 year^?1) or the grass mixture (up to 11 kg N ha^?1 year^?1). While runoff and erosion for cup plant and the grass mixture were negligible during the study period, considerable amounts of runoff water and eroded sediment of up to 1.5 Mg ha^?1 year^?1 were collected from the maize plots despite the near flat terrain of the experimental field. Overall, permanent cup plant proved suitable as a component for energy cropping systems to reduce the risk of N leaching and soil erosion, which is particularly important for the preventive flood protection in view of the more frequent occurrence of high intensity rainfall under climate change conditions.     

Vertical distribution and seasonal pattern of fine-root dynamics in a cool–temperate forest in northern Japan: implication of the understory vegetation, <Emphasis Type="Italic">Sasa</Emphasis> dwarf bamboo

We measured the vertical distribution and seasonal patterns of fine-root production and mortality using minirhizotrons in a cool–temperate forest in northern Japan mainly dominated by Mongolian oak (Quercus crispula) and covered with a dense understory of dwarf bamboo (Sasa senanensis). We also investigated the vertical distribution of the fine-root biomass using soil coring. We also measured environmental factors such as air and soil temperature, soil moisture and leaf area indices (LAI) of trees and the understory Sasa canopy for comparison with the fine-root dynamics. Fine-root biomass to a depth of 60 cm in September 2003 totaled 774 g m⁻², of which 71% was accounted for by Sasa and 60% was concentrated in the surface soil layer (0–15 cm), indicating that understory Sasa was an important component of the fine-root biomass in this ecosystem. Fine-root production increased in late summer (August) when soil temperatures were high, suggesting that temperature partially controls the seasonality of fine-root production. In addition, monthly fine-root production was significantly related to Sasa LAI (P<0.001), suggesting that fine-root production was also affected by the specific phenology of Sasa. Fine-root mortality was relatively constant throughout the year. Fine-root production, mortality, and turnover rates were highest in the surface soil (0–15 cm) and decreased with increasing soil depth. Turnover rates of production and mortality in the surface soil were 1.7 year⁻¹ and 1.1 year⁻¹, respectively.     

Mariculture and Natural Production of the Antitumoural (+)-Discodermolide by the Caribbean Marine Sponge Discodermia dissoluta

Biotechnological research on marine organisms, such as ex situ or in situ aquaculture and in vitro cell culture, is being conducted to produce bioactive metabolites for biomedical and industrial uses. The Caribbean marine sponge Discodermia dissoluta is the source of (+)-discodermolide, a potent antitumoural polyketide that has reached clinical trials. This sponge usually lives at depths greater than 30 m, but at Santa Marta (Colombia) there is a shallower population, which has made it logistically possible to investigate for the first time, on ways to supply discodermolide. We thus performed in situ, 6-month fragment culture trials to assess the performance of this sponge in terms of growth and additional discodermolide production and studied possible factors that influence the variability of discodermolide concentrations in the wild. Sponge fragments cultured in soft mesh bags suspended from horizontal lines showed high survivorship (93 %), moderate growth (28 % increase in volume) and an overall rise (33 %) in the discodermolide concentration, equivalent to average additional production of 8 μg of compound per millilitre of sponge. The concentration of discodermolide in wild sponges ranged from 8 to 40 μg mL^?1. Locality was the only factor related to discodermolide variation in the wild, and there were greater concentrations in peripheral vs. basal portions of the sponge, and in clean vs. fouled individuals. As natural growth and regeneration rates can be higher than culture growth rates, there is room for improving techniques to sustainably produce discodermolide.     

Harnessing Natural Recovery Processes to Improve Restoration Outcomes: An Experimental Assessment of Sponge-Mediated Coral Reef Restoration

Background

Restoration is increasingly implemented to reestablish habitat structure and function following physical anthropogenic disturbance, but scientific knowledge of effectiveness of methods lags behind demand for guidelines. On coral reefs, recovery is largely dependent on coral reestablishment, and substratum stability is critical to the survival of coral fragments and recruits. Concrete is often used to immobilize rubble, but its ecological performance has not been rigorously evaluated, and restoration has generally fallen short of returning degraded habitat to pre-disturbance conditions. Fragments of erect branching sponges mediate reef recovery by facilitating rubble consolidation, yet such natural processes have been largely overlooked in restoring reefs.

Methods

On two reefs in Curacao, four treatments - coral rubble alone, rubble seeded with sponge fragments, rubble bound by concrete, and concrete “rubble” bound by concrete - were monitored over four years to investigate rubble consolidation with and without sponges and the ecological performance of treatments in terms of the number and diversity of coral recruits. Species specific rates of sponge fragment attachment to rubble, donor sponge growth and tissue replacement, and fragment survival inside rubble piles were also investigated to evaluate sponge species performance and determine rates for sustainably harvesting tissue.

Findings/Significance

Rubble piles seeded with sponges retained height and shape to a significantly greater degree, lost fewer replicates to water motion, and were significantly more likely to be consolidated over time than rubble alone. Significantly more corals recruited to sponge-seeded rubble than to all other treatments. Coral diversity was also greatest for rubble with sponges and it was the only treatment to which framework building corals recruited. Differences in overall sponge species performance suggest species selection is important to consider. Employing organisms that jump start successional pathways and facilitate recovery can significantly improve restoration outcomes; however, best practices require techniques be tailored to each system.