Alan Duckworth

The discovery and development of marine compounds with pharmaceutical potential

An assessment of the current status of marine anticancer compounds is presented along with a case study on the aquaculture of Lissodendoryx n. sp. 1, a sponge that produces the antimitotic agents halichondrin B and isohomohalichondrin B. The use of polymer therapeutics to enhance the properties of marine natural products is considered.

Sponge aquaculture for the production of biologically active metabolites: the influence of farming protocols and environment

Abstract Before sponge aquaculture is accepted as a commercially viable method of supplying bioactive metabolites, it must be demonstrated that adequate production of sponge biomass and metabolite is possible. In this study, we farmed the New Zealand Demospongiae Latrunculia wellingtonensis (Alvarez, Bergquist and Battershill) and Polymastia croceus (Kelly-Borges and Bergquist) for 9 months at two nearby locations with differing flow rates using two farming methods: rope lines and suspended mesh arrays. The farmed explants were harvested at regular intervals over the 9 months by cutting and removing new biomass, leaving behind the original explant “core” to heal and regrow. For both species, explants grew as water temperature increased and shrunk as water temperature fell, and growth was greatest overall at the location with the greatest flow rate. Some treatments exhibited remarkable sponge growth (up to 960% in 6 months), with overall biomass yields double or greater the initial transplanted weight. Growth after harvesting was similar between harvested and nonharvested explants, indicating that healing of cut biomass and reorganization of the canal system is not a significant drain on resources. Bioactivity of farmed sponges (measure of bioactive metabolite biosynthesis) was similar or greater than found in natural populations. Both rope and mesh arrays were found to be good farming structures, but differing patterns of growth and survival indicated that the two arrays are most suited for a particular type of sponge depending on its skeletal structure.

Developing farming structures for production of biologically active sponge metabolites

Abstract A major obstacle to acceptance and use of sponge aquaculture as a viable method for production of biologically active metabolites is the lack of a farming technology suitable for commercial use. Using the New Zealand sponges Latrunculia sp. nov, Polymastia croceus and Raspailia agminata , all containing bioactive metabolites with biomedical potential, four general farming methods were examined: held on longline arrays sponge explants were farmed inside mesh support structures, rope threaded through explants and rope wrapped around explants. The fourth method additionally acted as a control procedure with sponge explants attached to substrate. Each general farming method was expanded to examine the effects of various mesh sizes and/or rope materials. Most methods were found to be unsuitable for commercial application because the farmed explants did not attach to the supporting substrate but instead grew away from it and were subsequently lost. The two methods that showed the most potential for large-scale sponge farming, in terms of good growth, survival and metabolite biosynthesis, were threaded polyvinyl alcohol rope and individual bags with large mesh size and thin strand diameter. These were developed into “rope” and “mesh” arrays that may be suitable for commercially farming sponges for metabolite production.

Population dynamics and chemical ecology of New Zealand Demospongiae Latrunculia sp. nov. and Polymastia croceus (Poecilosclerida: Latrunculiidae: Polymastiidae)

Abstract For 3 years aspects of the population dynamics, growth, and bioactivity (measure of biologically active metabolite biosynthesis) of the Demospongiae Latrunculia sp. nov. and Polymastia croceus (Kelly‐Borges & Bergquist) were examined on a subtidal reef on the Wellington south coast, New Zealand. For both species, survival of adult sponges was high in all seasons, whereas juvenile sponges had poor survival. Recruitment of Latrunculia sp. nov. occurred in all seasons indicating that this species is reproductively active throughout the year. P. croceus recruited mostly in autumn, supporting previous work that found the sponge to be reproductively active in summer and early autumn only. For both sponge species, growth rates varied greatly between individuals and were unaffected by initial sponge size within the range examined. Sponges generally grew during winter and spring as the water temperature rose, and shrank during summer and autumn as the water temperature fell. This growth pattern may relate to seasonal variation in food abundance, and for P. croceus it may result also from seasonal differences in reproductive investment. After 2 years, Latrunculia sp. nov. and P. croceus had on average, halved and doubled in size, respectively. Latrunculia sp. nov. showed a seasonal pattern of bioactivity, being most active in spring possibly to prevent the surface overgrowth of fouling organisms. P. croceus had no seasonal pattern of bioactivity, but individuals were either very active or inactive. The bioactive metabolites in both species possibly aid in competitive interactions and prevent predation and biofouling.

Effect of wound size on the growth and regeneration of two temperate subtidal sponges

Abstract Physical and biological disturbances can damage and remove biomass from marine invertebrates such as sponges. To determine the effect of wound size on sponge recovery, individuals of the Demospongiae Latrunculia wellingtonensis (Alvarez, Berqguist and Battershill) and Polymastia croceus (Kelly-Borges and Bergquist) had 50%, 75%, 90% or none (control) of their volume removed. Regeneration (measured by oscule development), growth (percent and volume change), biofouling and survival were monitored often over 203 days using in situ photographs. The rate of regeneration and growth varied between the two sponges, being greatest for L. wellingtonensis. Interspecific variation may result from differences in choanosome structure: the choanosome in L. wellingtonensis is poorly differentiated but is well developed in P. croceus. For each species, recovery rates were similar between 50%, 75% and 90% removed sponges. All damaged L. wellingtonensis and P. croceus survived, demonstrating the remarkable ability of some sponge species to recovery from massive injuries. L. wellingtonensis and P. croceus are often found in exposed habitats. Good recovery after injury may therefore be an adaptation to reduce the damaging effects of storms and strong water movement.