Condition-dependent responses of fish to motorboats.

Anthropogenic noise is a pollutant of global concern that has been shown to have a wide range of detrimental effects on multiple taxa. However, most noise studies to-date consider only overall population means, ignoring the potential for intraspecific variation in responses. Here, we used field experiments on Australia's Great Barrier Reef to assess condition-dependent responses of blue-green damselfish (Chromis viridis) to real motorboats. Despite finding no effect of motorboats on a physiological measure (opercular beat rate; OBR), we found a condition-dependent effect on anti-predator behaviour. In ambient conditions, startle responses to a looming stimulus were equivalent for relatively poor- and good-condition fish, but when motorboats were passing, poorer-condition fish startled at significantly shorter distances to the looming stimulus than better-condition fish. This greater susceptibility to motorboats in poorer-condition fish may be the result of generally more elevated stress levels, as poorer-condition fish had a higher pre-testing OBR than those in better condition. Considering intraspecific variation in responses is important to avoid misrepresenting potential effects of anthropogenic noise and to ensure the best management and mitigation of this pervasive pollutant.

Interactive effects of music tempi and intensities on grip strength and subjective affect.

Pretask music is widely used by athletes albeit there is scant empirical evidence to support its use. The present study extended a line of work into pretask music by examining the interactive effects of music tempo and intensity (volume) on the performance of a simple motor skill and subjective affect. A 2 × 2 within-subjects factorial design was employed with an additional no-music control, the scores from which were used as a covariate. A sample of 52 male athletes (Mage  = 26.1 ± 4.8 years) was exposed to five conditions: fast/loud (126 bpm/80 dBA), fast/quiet (126 bpm/70 dBA), slow/loud (87 bpm/80 dBA), slow/quiet (87 bpm/70 dBA) music, and a no-music control. Dependent variables were grip strength, measured with a handgrip dynamometer, and subjective affect, assessed by use of the Affect Grid. The tempo and intensity components of music had interactive effects for grip strength but only main effects for subjective affect. Fast-tempo music played at a high intensity yielded the highest grip strength, while fast-tempo music played at a low-intensity resulted in much lower grip strength (Mdiff.  = -1.11 Force kg). For affective valence, there were main effects of tempo and intensity, with fast and loud music yielding the highest scores. For affective arousal, there was no difference between tempi although there was between intensities, with the high-intensity condition yielding higher scores. The present findings indicate the utility of fast/loud pretask music in enhancing affective valence and arousal in preparation for a simple or gross motor task.

Fishes in a changing world: learning from the past to promote sustainability of fish populations.

Populations of fishes provide valuable services for billions of people, but face diverse and interacting threats that jeopardize their sustainability. Human population growth and intensifying resource use for food, water, energy and goods are compromising fish populations through a variety of mechanisms, including overfishing, habitat degradation and declines in water quality. The important challenges raised by these issues have been recognized and have led to considerable advances over past decades in managing and mitigating threats to fishes worldwide. In this review, we identify the major threats faced by fish populations alongside recent advances that are helping to address these issues. There are very significant efforts worldwide directed towards ensuring a sustainable future for the world's fishes and fisheries and those who rely on them. Although considerable challenges remain, by drawing attention to successful mitigation of threats to fish and fisheries we hope to provide the encouragement and direction that will allow these challenges to be overcome in the future.

The influence of various reef sounds on coral-fish larvae behaviour.

The swimming behaviour of coral-reef fish larvae from 20 species of 10 different families was tested under natural and artificial sound conditions. Underwater sounds from reef habitats (barrier reef, fringing reef and mangrove) as well as a white noise were broadcasted in a choice chamber experiment. Sixteen of the 20 species tested significantly reacted to at least one of the habitat playback conditions, and a range of responses was observed: fishes were (1) attracted by a single sound but repelled by none (e.g. white-banded triggerfish Rhinecanthus aculeatus was attracted by the barrier-reef sound), (2) repelled by one or more sounds but attracted by none (e.g. bridled cardinalfish Pristiapogon fraenatus was repelled by the mangrove and the bay sounds), (3) attracted by all sounds (e.g. striated surgeonfish Ctenochaetus striatus), (4) attracted and repelled by several sounds (e.g. whitetail dascyllus Dascyllus aruanus was attracted by the barrier-reef sound and repelled by the mangrove sound) and (5) not influenced by any sound (e.g. convict surgeonfish Acanthurus triostegus). Overall, these results highlight two settlement strategies: a direct selection of habitats using sound (45% of the species), or a by-default selection by avoidance of certain sound habitats (35%). These results also clearly demonstrated the need to analyse the influence of sounds at the species-specific level since congeneric and confamilial species can express different behaviours when exposed to the same sounds.

Vertical and horizontal distributions of coral-reef fish larvae in open water immediately prior to reef colonization.

To explore the vertical and horizontal distributions of fish larvae near the end of their pelagic period, six light traps were set up over four lunar months at different depths (sub-surface, midwater and bottom) and different habitat types (reef slope: 50 m horizontal distance from the reef crest; frontier zone: 110 m horizontal distance; sandy zone: 200 m horizontal distance) on the outer reef slope of Moorea Island, French Polynesia. The highest captures were in sub-surface traps on the reef slope and the frontier zone, and in bottom traps on the sandy zone and the frontier zone. It is hypothesized that fish larvae move towards the surface near the reef slope to avoid reef-based planktivores and to get into a favourable position for surfing over the reef crest.

Behaviour of mesopredatory coral reef fishes in response to threats from sharks and humans.

Both sharks and humans present a potentially lethal threat to mesopredatory fishes in coral reef systems, with implications for both population dynamics and the role of mesopredatory fishes in reef ecosystems. This study quantifies the antipredator behaviours mesopredatory fishes exhibit towards the presence of large coral reef carnivores and compares these behavioural responses to those elicited by the presence of snorkelers. Here, we used snorkelers and animated life-size models of the blacktip reef shark (Carcharhinus melanopterus) to simulate potential predatory threats to mesopredatory reef fishes (lethrinids, lutjanids, haemulids and serranids). The responses of these reef fishes to the models and the snorkelers were compared to those generated by three non-threatening controls (life-size models of a green turtle [Chelonia mydas], a PVC-pipe [an object control] and a Perspex shape [a second object control]). A Remote Underwater Stereo-Video System (Stereo-RUV) recorded the approach of the different treatments and controls and allowed accurate measurement of Flight Initiation Distance (FID) and categorization of the type of flight response by fishes. We found that mesopredatory reef fishes had greater FIDs in response to the approach of threatening models (1402 ± 402-1533 ± 171 mm; mean ± SE) compared to the controls (706 ± 151-896 ± 8963 mm). There was no significant difference in FID of mesopredatory fishes between the shark model and the snorkeler, suggesting that these treatments provoked similar levels of predator avoidance behaviour. This has implications for researchers monitoring behaviour in situ or using underwater census as a technique to estimate the abundance of reef fishes. Our study suggests that, irrespective of the degree to which sharks actually consume these mesopredatory reef fishes, they still elicit a predictable and consistent antipredator response that has the potential to create risk effects.

A novel sialic acid binding site on factor H mediates serum resistance of sialylated Neisseria gonorrhoeae.

Factor H (fH), a key alternative complement pathway regulator, is a cofactor for factor I-mediated cleavage of C3b. fH consists of 20 short consensus repeat (SCR) domains. Sialic acid binding domains have previously been localized to fH SCRs 6-10 and 13. To examine fH binding on a sialylated microbial surface, we grew Neisseria gonorrhoeae in the presence of 5'-cytidinemonophospho-N-acetylneuraminic acid, which sialylates lipooligosaccharide and converts to serum resistance gonococci previously sensitive to nonimmune serum killing. fH domains necessary for binding sialylated gonococci were determined by incubating organisms with recombinant human fH (rH) and nine mutant rH molecules (deletions spanning the entire fH molecule). rH and all mutant rH molecules that contained SCRs 16-20 bound to the sialylated strain; no mutant molecule bound to serum-sensitive nonsialylated organisms. Sialic acid was demonstrated to be the fH target by flow cytometry that showed a fourfold increase in fH binding that was reversed by neuraminidase-mediated cleavage of sialic acid off gonococci. Functional specificity of fH was confirmed by decreased total C3 binding and almost complete conversion to iC3b on sialylated gonococci. Sialic acid can therefore bind fH uniquely through SCRs 16-20. This blocks complement pathway activation for N. gonorrhoeae at the level of C3.

Restoring depleted coral-reef fish populations through recruitment enhancement: a proof of concept.

To determine whether enhancing the survival of new recruits is a sensible target for the restorative management of depleted coral-reef fish populations, settlement-stage ambon damsel fish Pomacentrus amboinensis were captured, tagged and then either released immediately onto small artificial reefs or held in aquaria for 1 week prior to release. Holding conditions were varied to determine whether they affected survival of fish: half the fish were held in bare tanks (non-enriched) and the other half in tanks containing coral and sand (enriched). Holding fish for this short period had a significantly positive effect on survivorship relative to the settlement-stage treatment group that were released immediately. The enrichment of holding conditions made no appreciable difference on the survival of fish once released onto the reef. It did, however, have a positive effect on the survival of fish while in captivity, thus supporting the case for the provision of simple environmental enrichment in fish husbandry. Collecting and holding settlement-stage fish for at least a week before release appear to increase the short-term survival of released fish; whether it is an effective method for longer-term enhancement of locally depleted coral-reef fish populations will require further study.

Group navigation and the "many-wrongs principle" in models of animal movement.

Traditional studies of animal navigation over both long and short distances have usually considered the orientation ability of the individual only, without reference to the implications of group membership. However, recent work has suggested that being in a group can significantly improve the ability of an individual to align toward and reach a target direction or point, even when all group members have limited navigational ability and there are no leaders. This effect is known as the "many-wrongs principle" since the large number of individual navigational errors across the group are suppressed by interactions and group cohesion. In this paper, we simulate the many-wrongs principle using a simple individual-based model of movement based on a biased random walk that includes group interactions. We study the ability of the group as a whole to reach a target given different levels of individual navigation error, group size, interaction radius, and environmental turbulence. In scenarios with low levels of environmental turbulence, simulation results demonstrate a navigational benefit from group membership, particularly for small group sizes. In contrast, when movement takes place in a highly turbulent environment, simulation results suggest that the best strategy is to navigate as individuals rather than as a group.

Patterns of activity expressed by juvenile horseshoe crabs.

Adult American horseshoe crabs, Limulus polyphemus, possess endogenous circadian and circatidal clocks controlling visual sensitivity and locomotion, respectively. The goal of this study was to determine the types of activity rhythms expressed by juvenile horseshoe crabs (n = 24) when exposed to a 14:10 light/dark cycle (LD) for 10 days, followed by 10 days of constant darkness (DD). Horseshoe crab activity was recorded with a digital time-lapse video system that used an infrared-sensitive camera so animals could be monitored at night. In LD, 15 animals expressed daily patterns of activity, 6 displayed a circatidal pattern, and the remaining 3 were arrhythmic. Of the 15 animals with daily patterns of locomotion, 7 had a significant preference (P < 0.05) for diurnal activity and 3 for nocturnal activity; the remainder did not express a significant preference for day or night activity. In DD, 13 horseshoe crabs expressed circatidal rhythms and 8 maintained a pattern of about 24 h. Although these results suggest the presence of a circadian clock influencing circatidal patterns of locomotion, these apparent circadian rhythms may actually represent the expression of just one of the two bouts of activity driven by the putative circalunidian clocks that control their tidal rhythms. Overall, these results indicate that, like adults, juvenile horseshoe crabs express both daily and tidal patterns of activity and that at least one, and maybe both, of these patterns is driven by endogenous clocks.

Mice with the xid mutation lack the regulatory antibodies that are necessary for the induction of contrasuppression.

We present evidence that mice with X-linked immunodeficiency (xid) lack circulating regulatory immunoglobulin (reg Ig) necessary for control of antigen-specific suppressor T cells (Ts). Previous work demonstrated that reg Ig is one component of a serum factor that blocks Ts activity, thereby allowing appropriate antibody responses invivo and in vitro. These factors are referred to as contrasuppressor factors (CSF). CSF are detected in the serum of mice 3-6 hr after immunization with SRBC or can be generated in vitro by combining normal mouse serum with supernatants of macrophage-T cell cocultures (M phi-T sup). Data presented here demonstrate that CSF were not detectable in the serum of immunized xid mice. Serum from xid mice or affinity-purified serum IgG and IgA failed to generate CSF in vitro, indicating a lack of reg Ig in xid serum. However, xid T cells could block suppression of isotype-specific antibody responses in vitro when incubated with functional CSF containing M phi-T sup and CBA/J reg IgG or IgA. Similarly, xid macrophages showed no defect in generation of functional M phi-T sup in vitro. Finally, CBA/J Vicia villosa adherent (Vv) T cells that were incubated with in vitro generated CSF allowed anti-SRBC responses in vivo, when adoptively transferred into xid mice, prior to SRBC immunization. These responses were comparable to those of normal CBA/J mice immunized with SRBC. Similarly, xid mice that received xid T cells treated with CSF and were immunized with SRBC generated good anti-SRBC PFC responses. These studies provide strong evidence that xid mice lack circulating reg Ig resulting in defective CSF and consequently low antibody responses to SRBC, due to dominant Ts activity.

T lymphocyte response to Neisseria gonorrhoeae porin in individuals with mucosal gonococcal infections.

T lymphocytes from a majority of patients with urogenital gonococcal disease (67%-80%) proliferated on incubation with gonococcal porin (Por), compared with minimal induced proliferation of T lymphocytes from normal volunteers. A significant increase in Por-specific interleukin (IL)-4-producing CD4+ T helper lymphocytes was seen in patients with mucosal gonococcal disease and not in normal controls. Similar results were observed in CD8+ T lymphocytes from these patients. There was no measured increase in IL-2, IL-10, IL-12, interferon-gamma, or tumor necrosis factor-alpha production by T lymphocytes from infected subjects on incubation with Por. Concomitant increases in IL-4 production in T lymphocytes from infected subjects expressing the mucosal addresin VLAalpha4/beta7 on their surface were also observed on Por incubation, but the increases were similar in T lymphocytes that were VLAalpha4/beta7 negative. In conclusion, mucosal gonococcal disease can induce Por-specific circulating T lymphocytes with a Th2 phenotype, and a portion of these Por-specific T lymphocytes can potentially traffic to mucosal surfaces.

Short chain oligogalacturonides induce ethylene production and expression of the gene encoding aminocyclopropane 1-carboxylic acid oxidase in tomato plants.

Oligogalacturonic acids (OGAs), derived from plant cell wall pectin, have been implicated in a number of signal transduction pathways involved in growth, development and defense responses of higher plants. This study investigates the size range of OGAs capable of inducing ethylene synthesis in tomato plants, and demonstrates that in contrast with many other effects, only short chain OGAs are active. Oligomers across a range of DP from 2-15 were separated and purified to homogeneity by QAE-Sephadex anion exchange chromatography using a novel elution system. The OGAs were applied to tomato plants and assayed for their ability to induce ethylene gas release and changes in steady state levels of mRNA encoding the ethylene forming enzyme aminocyclopropane-1-carboxylic acid oxidase (ACO). The study demonstrated that only OGAs in the size range of DP4-6 were active both in eliciting ACO expression and in the production of ethylene.

Soluble FcR block suppressor T cell activity at low concentration in vitro allowing isotype-specific antibody production.

IgA and IgG binding factors (BF) can be found in the supernatant (Th sup) of cultures containing macrophages and CD4+ T cells stimulated with particulate antigens such as SRBC. Previous work indicated that these IgBF, when mixed with normal serum immunoglobulin, could block the activity of suppressor T cells (Ts) and allow IgA and IgG PFC responses in vitro. We present serologic and functional evidence that IgABF and IgGBF in Th sup are soluble Fc alpha R and Fc gamma RII (or III), respectively. Th sup adsorbed on affinity columns containing anti-Fc gamma RII/III mAB or murine IgG failed to augment IgG PFC responses. Material eluted from either the IgG or anti-Fc gamma RII/III columns could be added back, interchangeably, to the adsorbed Th sup and restore IgG PFC. Recombinant murine Fc gamma RII(rFc gamma RII), added to the same adsorbed Th sup at 0.01 to 0.5 ng/ml, resulted in a similar augmentation of IgG PFC. Interestingly, much higher concentrations of rFc gamma RII (10-100 ng/mL) could not augment IgG PFC responses. Protein dot blots showed that Th sup and the eluted material from murine IgG columns contained structures reactive with the Fc gamma RII/III mAb. Similar studies using purified Fc alpha R revealed that IgABF eluted from IgA or anti-Fc alpha R revealed that IgABF eluted from IgA or anti-Fc alpha R columns was in fact Fc alpha R. Cross-adsorption studies indicated clearly that the IgGBF (Fc gamma RII/III) and the IgABF (Fc alpha R) were separate molecules produced in the same Th sup and that each regulated their respective Ig isotype independently. Thus, cultures of splenic macrophage and CD4+ T cells, in the presence of particulate antigens such as SRBC, generate both Fc gamma RII/III and Fc alpha R. This soluble FcR in combination with serum Ig act to block isotype specific Ts cells at low concentration in vitro.