Dispersal of Symbiodinium by the stoplight parrotfish Sparisoma viride

Environmental reservoirs of zooxanthellae are essential for coral larvae settlement; understanding where they occur and how they are maintained is important for coral reef ecology. This study investigated the dispersal of Symbiodinium spp. by the stoplight parrotfish Sparisoma viride, which had high mean densities of viable and cultivable Symbiodinium (3207-8900 cells ml(-1)) in faeces. Clades A, B and G were detected using amplified chloroplast ribosomal sequences (cp23S-HVR), and corresponded with diet preferences of fish and the environmental Symbiodinium diversity of the region. Cells are constantly dispersed in the water column and deposited in the substrate at a local level (86 ± 17.8 m(2)), demonstrating that parrotfishes are vectors for short-distance dispersal of zooxanthellae. Such dispersal could constitute a key role in the maintenance of environmental Symbiodinium reservoirs.     

Small‐scale demographic variation in the stoplight parrotfish Sparisoma viride

Age‐based analysis of the stoplight parrotfish Sparisoma viride was used to examine whether observed differences in their abundance and size structure among reefs in a cross‐shelf portion of the upper Florida Keys could be explained by variation in demographic rates. Annual and daily sagittal otolith increments were enumerated for 176 individuals collected from replicates of reefs in two strata, inshore and offshore reefs (2–6 m depth). von Bertalanffy growth functions fitted to size‐at‐age plots for each site were similar between reefs within each stratum (inshore and offshore), but differed between strata. Sparisoma viride on offshore reefs attained greater average standard length (L_S) at age, greater mean asymptotic size and were longer lived than fish from inshore reefs. Fish on inshore reefs attained only half the maximum age observed on offshore reefs (4 v. 8 years, respectively). No terminal phase fish >4 years of age were found on either reef type. Estimates of mortality rates from age‐frequency data of collected fish revealed higher mortality on inshore reefs. Demographic variables obtained in this study were similar to published values for S. viride from Caribbean reefs but differed significantly from published values from reefs at a similar latitude (Bahamas), reflecting high demographic plasticity on both local and regional scales.     

Resource and habitat sharing by the stoplight parrotfish,Sparisoma viride, a Caribbean reef herbivore

Synopsis We compare the vertical distribution, substrate preferences, grazing behaviour and social interactions of the stoplight parrotfish,Sparisoma viride, with that of other scarids at a fringing reef off Bonaire (Netherlands Antilles). Earlier reports thatS. viride only displays territorial behaviour against conspecifics are confirmed by the non-aggressive nature of this parrotfish and the low time expenditure on interactions with other herbivores. The vertical distribution ofS. viride is largely identical to that of several other scarids, acanthurids and pomacentrids, whose ranges may completely coincide withS. viride territories. Comparison of the substrate use of the five most common scarids inside a singleS. viride territory yields no evidence of food partitioning. We suggest that the lack of interspecific territorial behaviour inS. viride is explained by the inability to economically defend a territory against all potential food competitors. Factors that may favour territory sharing between herbivores are fine-scale resource partitioning and shared defence, both of which would reduce the costs of territorial life. However, more detailed investigation of herbivore food selection is required before definite conclusions can be drawn.     

Effects of substrata, resident conspecifics and damselfish on the settlement and recruitment of the stoplight parrotfish, Sparisoma viride

Recruitment plays an important role in the population dynamics of marine organisms and is often quantified as a surrogate for settlement. When quantified, recruitment includes settlement plus a period of time in the benthic habitat. Therefore, it is essential to determine whether post-settlement processes alter patterns established at settlement. I conducted a series of experiments on 2.0 m² patch reefs to examine the importance of pre- and post-settlement processes to the distribution and abundance of recruits of the stoplight parrotfish, Sparisoma viride, on the Tague Bay reef, St. Croix, USVI. Recruitment was higher to the coral Porites porites than to another common coral Montastrea annularis, but there was no evidence of microhabitat choice at settlement. This result, in conjunction with the examination of the size classes of recruits present on P. porites and M. annularis patch reefs in a separate experiment suggested that differences in recruitment were established after settlement. Stoplights settled in higher numbers to patch reefs that contained conspecific residents, and persistence was higher at higher recruit density. Although resident damselfish directed significant amounts of agonistic behavior towards newly stoplight recruits, damselfish presence had no effect on settlement. However, damselfish presence did reduce stoplight recruitment. These results demonstrate that both pre- and post-settlement processes influence the recruitment of stoplight parrotfish. More importantly, these results indicate that benthic processes can alter recruitment patterns from initial settlement patterns, and indicate that workers should be careful in using recruitment as a proxy for settlement.     

Androgen control of social status in males of a wild population of stoplight parrotfish, Sparisoma viride (Scaridae)

In the protogynous stoplight parrotfish (Sparisoma viride), large males defend territories that encompass the home-ranges of several mature females. However, high-quality habitat is in short supply, such that smaller, competitively inferior males do not defend territories. We investigated the role of 11-ketotestosterone (11KT) and testosterone (T) in the regulation of territorial behavior in a wild population of a protogynous reef fish, the stoplight parrotfish, at Glover's Reef, Belize. Radioimmunoassay of plasma samples from individuals of known social status revealed that nonterritorial males have lower levels of T and 11KT than territorial males. Nonterritorial males allowed access to vacant territories underwent pronounced increases in T and 11KT. When sampled 1 week after territory acquisition, levels of T and 11KT in new territorial males were significantly higher than the levels in established territorial males, but by 3 weeks after territory acquisition, there was no significant difference. We further investigated the hypothesis that such short-term increases in androgen levels are a response to intense male-male interactions during territory establishment. Simulated territorial intrusion promoted increased plasma levels of both T and 11KT while access to vacant territories without neighboring territorial males did not. These findings suggest that the endocrine system plays a role in fine-tuning the levels of territorial aggression exhibited by male stoplight parrotfish. We discuss these results in light of recent theory in behavioral endocrinology.     

Destruction of corals and other reef animals by coral spawn slicks on Ningaloo Reef,Western Australia

In March 1989, most of the corals near Coral Bay, off the north-western coastline of Australia, spawned several nights earlier than usual. Flood, rather than ebb, tides at the time of spawning combined with light north-west winds and low swell conditions to restrict the dispersal of coral propagules and, as a result, large amounts of coral spawn were trapped in the bay, forming extensive slicks. Fish and other animals began to die almost immediately, and over the next few days, over 1 million fish, representing at least 80 species, were washed ashore. A survey of the benthic communities revealed extensive mortality of corals and other reef animals over an area of about 3 km². Live coral cover in this area decreased from 42.9% to 9.4% and several large coral colonies up to 10 m in diameter were killed. The observed mortality was presumably the result of hypoxia (oxygen depletion) created initially by the respiratory demand of the coral spawn and maintained by the biological oxygen demand of the decomposing spawn slicks and dead animals. Anecdotal reports of corals and other reef animals dying in the vicinity of coral spawn slicks on other reefs in Western Australia suggest that this phenomenon may be a relatively common event on shallow coral reefs where coral mass spawning occurs. These records and observations document, for the first time, a new source of natural disturbance that has a significant influence on the community structure of some coral reefs.     

Hyphal invasion by Trichoderma viride

Conclusions From these observations one might conclude thatTrichoderma viride, whether or not it exudes an antibiotic, does attack other fungi parasitically, especially phycomycetes, directly penetrating the host and digesting its contents.     

Bioaccumulation of copper by Trichoderma viride

Studies were carried out on interaction of Trichoderma viride with copper and reports bioaccumulation as a mechanism of copper tolerance during growth. There was a marked increase in the lag phase of the growth, which was concentration dependent. At a concentration of 100 mg/L of CuCl2.2H2O, 81% of Cu(II) were removed by 3.4 g/L of the biomass in 72 h. The process was temperature and pH dependent. The maximum copper bioaccumulation occurred at 30 degrees C, pH 5.0. Metabolic inhibitors such as sodium azide (NaN3) and 2,4-dinitrophenol (2,4-DNP) drastically reduced the extent of Cu(II) bioaccumulation. Electron microscopy and cell fractionation studies revealed that 70-80% of copper was present as a layer on the cell wall surface.     

The infection of oranges by Trichoderma viride and mixed infection by Trichoderma viride and Penicillium digitatum

Trichoderma viride spores applied in water to apparently uninjured skin of oranges do not cause lesions. Adding orange juice, rind extract, citric acid or orange essential oil did not influence infection. Oranges became infected only when the stem-end cuts or wounds deeper than 6 mm into oil vesicles were inoculated. Sound oranges in contact with decayed oranges did not become infected. Diphenyl-impregnated wrappers reduced infection. A mixed inoculum of T. viride and Penicillium digitatum caused as fast rotting as P. digitatum, which caused faster rotting than T. viride alone. Lesions infected with P. digitatum could become infected by T. viride but those caused by T. viride did not become infected by P. digitatum. T. viride was antagonistic to P. digitatum in vivo and in vitro, possibly because it produces a heat-labile diffusible substance toxic to P. digitatum.     

Adsorption of cellulose by Trichoderma viride

Adsorption of cellulase by Trichoderma viride QM 9414 has been studied with resting and growing cells and equations have been derived to describe the process quantitatively. It has been observed that the adsorption is a purely physical process being dependent only on cell and cellulose concentrations. It has also been demonstrated that adsorption isrequired for the induction of cellulases; some discussions are devoted to this point.     

Destruction of concrete by nitrification

Summary Nitrification was studied, using samples of asbestos concrete plates and water, both taken from a cooling tower, in which ammonia-containing water had been circulated for several years. Almost the entire nitrifying activity and the majority of autotrophic nitrifying bacteria were found to be located in the coating, covering the asbestos concrete plates. When sprinkled over these plates, the H⁺-concentration of such ammonia-containing water increased from neutrality to about pH 5.3 and this pH was maintained as long as nitrification was feasible. Death of microorganisms and lack of either ammonia or oxygen caused a rapid decrease of H⁺-concentration, which was obviously due to concrete destruction. The temporary acidification observed in the medium resulted from both acid-producing microbial nitrification and acid consuming concrete dissolution, with both reactions counteracting each other. The amount of nitric acid required to maintain a low pH in presence of concrete was determined by automatic titration. The obtained result indicated that considerable amounts of nitric acid might have been formed in the cooling system, which could well account for the observed damage.     

Degradation of Cellulosic Materials by Trichoderma viride Cellulase

The extra-cellular filtrates of Trichoderma viride ITCC–1433 showed considerable cellulolytic activity against native celluloses, cellulose derivatives and raw materials. Newspaper-yellow and the rice straw were the prominent waste materials which were preferentially attacked by the enzyme. The alkali treatment of the latter doubled the sugar formation from it. As a result of cellulase action 80.4 per cent of the MN-Cellulose and 60.4 per cent of the alkali treated rice straw lost weight in 96 and 48 hr respectively. The weight loss was more or less equivalent to the reducing sugars formed.     

Suppression of photo-induced sporulation inTrichoderma viride by inhibitors

The mycelium ofTrichoderma viride grown in the dark under submerged conditions and transferred to membrane filters sporulated only after photoinduction. The optimum photoinduction of sporulation was reached when applying daylight for 3 min and near ultraviolet radiation (366 nm) for 10 to 30 sec. After the photoinduction pronounced synthesis of DNA, RNA and protein was observed. The photoinduced sporulation was partially or fully inhibited in the presence of phenethyl alcohol, actinomycin D, 5-fluorouracil, cycloheximide and ethidium bromide. The same inhibitors blocked also the photoinduced sporulation of surface growing colonies ofTrichoderma viride. Various inhibitors of synthesis of nucleic acids and protein, inhibitors impairing the function of membranes and certain other compounds were also effective. A part of the results presented here was included in the dissertation of J.S. and defended at the Slovak Polytechnical University in Bratislava.     

Biodegradation of wastepaper by cellulase from Trichoderma viride

Environmental issues such as the depletion of non-renewable energy resources and pollution are topical. The extent of solid waste production is of global concern and development of its bioenergy potential can combine issues such as pollution control and bioproduct development, simultaneously. Various wastepaper materials, a major component of solid waste, were treated with the cellulase enzyme from Trichoderma viride, thus bioconverting their cellulose component into fermentable sugars. All wastepaper materials exhibited different susceptibilities towards the cellulase as well as the production of non-similar sugar releasing patterns when increasing amounts of paper were treated with a fixed enzyme concentration. The hydrolysis of wastepaper with changing enzyme concentrations and incubation periods also resulted in dissimilar sugar-producing tendencies. A general decline in hydrolytic efficiency was observed when increasing sugar concentrations were produced during biodegradation of all wastepaper materials.     

Stimulation of conidiation by derivatives of cAMP inTrichoderma viride

Derivatives of cyclic-3′,5′-adenosine monophosphate, N⁶,2′-O-dibutyryl-cAMP, 8-(chlorophenylthio)-cAMP and 8-bromoadenosine-cAMP added at 0.1–10 μmol/L concentrations into the growth medium have markedly stimulated conidiation inTrichoderma viride. Their stimulatory effect on conidiation was best observed in colonies that were constantly kept in the dark but was also marked in colonies illuminated by sub-saturating doses of light. The relative stimulation of conidiation depended not only on the concentration of exogenous cyclic nucleotides but also on the concentration of glucose in the medium. It was more pronounced in glucose-rich media than in media where the concentration of the sugar was low. Concentrations of cAMP analogues equal to 50 μmol/L and higher inhibited the conidiation.