Abundance and arm loss of the infaunal brittlestar Ophiophragmus filograneus (Echinodermata: Ophiuroidea), with an experimental determination of regeneration rates in natural and planted seagrass beds

The regeneration rate of arms of the infaunal brittlestar Ophiophragmus filograneus was determined in natural and planted beds of the seagrass (Halodule wrighttii) in Tampa Bay, Florida, USA in 1990. Annually, brittlestar densities did not differ on average between the two beds, but they did show marked differences on individual dates. Rates of arm loss could not be determined for the two sites separately, but were estimated for the entire area. Between 52 and 94% of the brittlestars collected showed evidence of arm regeneration. Approximately one-third of those collected were regenerating one arm, with smaller proportions regenerating two or more arms. Regeneration rate was greater overall for individuals that had lost more tissue; however, the rate of soft-tissue regeneration per arm regenerated was significantly greater for those that had lost one arm compared to those that had lost three arms. The rate of soft-tissue regeneration did not differe between individuals from the two seagrass beds, and regeneration rate was lower than reported for other infaunal brittlestars. Skeletal regeneration per arm was similar in both arm-removal treatments. This result supports the hypothesis that echinoderm skeleton is energetically inexpensive and may help to lengthen arms during early regeneration. The rate of skeletal production was three-fold greater in individuals from the planted seagrass than in those from the natural. bed. As increased skeletal regeneration requires some additional energy, this indicates a greater energy expenditure and differential allocation by brittlestars regenerating in the planted seagrass areas.     

Long-term mate and territory fidelity in neotropical buff-breasted wrens (Thryothorus leucotis)

Among sedentary species, mate and site fidelity may be imposed by year-round territoriality and high annual survivorship, both of which theoretically lead to few opportunities to move between mates and breeding territories. We examined mate and territory fidelity in sedentary neotropical buff-breasted wrens (Thryothorus leucotis) in relation to the opportunities to divorce (vacancies on neighbouring territories), breeding experience and site of origin (within vs outside local breeding population). Overall, buff-breasted wrens showed high rates of mate and territory fidelity between years, with individuals significantly more faithful to their territories than to their partners. Mate and territory fidelity was not forced upon buff-breasted wrens, as most individuals had opportunities to switch mates and territories. However, this was not uniform among all individuals. Individuals that had bred together displayed 100% mate and territory fidelity despite the fact that males and females in almost all experienced pairs had opportunities to switch mates and territories. Local recruits (philopatric offspring that acquired territories in the local breeding population) also displayed mate and territory fidelity, but fidelity occurred because recruits rarely had the opportunity to divorce prior to initiating their first breeding attempt. By contrast, almost half of all territorial individuals that originated outside the local breeding population (immigrants) had opportunity to divorce, with approximately two thirds of them switching mates and territories. Divorces occurred within the first 5 months of pairing, suggesting that immigrants may have sampled mates and territories before forming permanent partnerships.     

Venoms from six species of marine fish: lethal and hemolytic activities and their neutralization by commercial stonefish antivenom

A specimen of the stonefish Synanceja verrucosa was captured in Okinawa in March 1988. Live specimens of the scorpionfish Inimicus japonicus were purchased from the Tokyo Central Wholesale Market in November 1988 and those of four species of zebrafish Pterois lumulata, P. volitans, P. antennata and Dendrochirus zebra from an aquarium in December 1988. Crude venoms were extracted from dorsal spines of the six species. All venoms exhibited lethal activity against mice and hemolytic activity specific for rabbit erythrocytes. The lethal activity (or hemolytic activity) of each venom was very unstable to freezing, lyophilization and heating. Both lethal and hemolytic activities of S. verrucosa venom were remarkably neutralized by the commerical stonefish (Synanceja trachynis) antivenom. This antivenom was also effective, to some extent, in counteracting the other venom activities. The neutralizing capacities of the antivenom were calculated to be 7310 LD₅₀ ml^-1 for S. verrucosa venom and 1 220 to 2 990 LD₅₀ ml^-1 for the other venoms. Results of neutralization tests suggest that venoms from the six species were comparable in terms of antigenecity.     

Self-fertilization and maternal enzymes in the planulae of the coral Goniastrea favulus

Electrophoretic analysis of planulae obtained from controlled breeding experiments with the coral Goniastrea favulus during spawning events in 1986 and 1987 on the Great Barrier Reef, Australia, shows that offspring are produced equally frequently by outcrossing or self-fertilization, leading to a genetically determined rate of selfing of around 50%. Field rates of selfing may be greater than this as a consequence of the limited dispersal of gametes within this species. However, the level of heterozygote depression found in one population is well below that which would be predicted for such levels of selfing. In one enzyme system, glucosephosphate isomerase, the maternal phenotype continues to be expressed in the planula larva for between 11 and 17 d after fertilization. This effect is postulated to result from a residual of maternal enzyme and RNA derived from a relatively large egg.     

Mother-infant behavior in vervet monkeys

Summary Mother-infant behavior of 9 vervet monkey mothers who had failed in their last pregnancy were compared to the behavior of 14 mothers who had been successful in the prior year and to 11 primiparous mothers. The results indicated that females responded to the loss of one infant by increasing their level of care for their next infant. Females who had failed in their last pregnancy encouraged ventral contact and were more restrictive of their infant's movements, they gave more care and attention to their infants, and they played a greater part in keeping their infants near, compared to mothers who had been successful in their last pregnancy. Mothers who had failed in their last pregnancy were also more attentive and protective toward their infants than primiparous mothers who had had no prior reproductive experience. The increase in maternal care by females who had failed in their last pregnancy was accompanied by an increase in the interval to the birth of their next infant. These differences could not be completely explained by differences in the mothers' age or in the presence of other immature offspring. They suggest that vervet mothers can adjust their level of parental care based on the quality of their past experience, and that these adjustments have an effect on the mother's future reproductive potential.     

Diversionary displays of paternal stickleback

Summary In Crystal Lake, British Columbia, male threespine stickleback (Gasterosteus aculeatus) perform a diversionary display that deters cannibalistic conspecifics from entering their territories and destroying their nests or consuming offspring. In this population, the display consists of males swimming directly out of their territories and rooting aggressively in the substratum, mimicking stickleback feeding on nests of others, or digging for nesting materials. The display is elicited solely by conspecifics, and usually by benthic foraging groups of 2–300 individuals. It usually is elicited when groups are approaching the territory directly. Otherwise the male typically joins the group or remains still in his territory until the group leaves. This observation suggests that males are capable of discriminating conditions under which the display is most likely to be successful. The display is absent in a population in Garden Bay Lake, British Columbia, in which benthic foraging groups are absent. In Crystal Lake the males themselves do not risk predation by the groups, and the tendency of males to perform the display does not change with reproductive condition. Comparison with diversionary displays performed in two additional allopatric populations suggests that diversionary displays in this species incorporate elements of other behavioral sequences displaced to the display, and that variation in the structure of the display exists among populations.     

Toxicity of copper to the marine amphipod Allorchestes compressa in the presence of water-and lipid-soluble ligands

Acute toxicity tests were carried out on the marine amphipod Allorchestes compressa Dana using copper sulphate and some organocopper complexes. For copper sulphate, 96 h LC₅₀ values of 0.11 and 0.5 mg Cu l^-1 were determined for the juveniles and the adults, respectively, juveniles being 4.5 times more sensitive to copper than adults. Organocopper complexes were tested on adults only. The three water-soluble ligands nitrilotriacetic acid, 8-hydroxyquinoline-5-sulphonic acid and tannic acid ameliorated copper toxicity by decreasing the concentration of free ionic copper, while lipid-soluble ligands such as oxine and potassium ethylxanthogenate increased copper toxicity, presumably as a result of the complexes diffusing through the cell membrane and participating in injurious reaction. The copper complex with 2,9-dimethyll, 10-phenanthroline was the most toxic complex tested. It is suggested that the presence of these ligands in the receiving water should be taken into consideration when establishing water-quality criteria.     

Functional autotrophy of Heteroxenia fuscescens (Anthozoa: Alcyonaria): carbon assimilation and translocation of photosynthates from symbionts to host

The association of the alcyonarian Heteroxenia fuscescens (Ehrb.) with its cytosymbiotic algae shows structural and physiological adaptations optimizing the living together of the two partners as one functional unit. To enhance the energetic contribution of the autotrophic partner, the organization of the heterotrophic partner bears typical plant-like imprints. Up to 20% of the inorganic C photosynthetically fixed was translocated to the host (=2 mg C mg d.w.^-1 d^-1). This net C gain by the host is used for anabolic purposes including the deposition of storage material. Especially the wax-esters and triglycerides of the host-in contrast to those of the symbionts-were intensively labelled. The in-vivo ¹⁴C-fixation of zooxanthellae is more than double the in-vitro fixation. In both symbionts and host, the lipids show the highest relative ¹⁴C-incorporation. In particular the polyol component was strongly labelled. After 120 min of continuous incubation, approximately 40 labelled intracellular metabolites were detectable in the ethanol/water soluble fractions of zooxanthellae. Glycerol is the main low-molecular weight carbohydrate being transferred. This is corroborated by the deacylation of lipids of the host.