Efecto del dragado de un canal de comunicación al mar (estero) sobre la asociación de peces en la Laguna Larga, Cayo Coco, Cuba

En este trabajo se caracterizaron el hábitat y la comunidad de peces en el canal de comunicación al mar de Laguna Larga, antes y después de un proceso de dragado realizado en el año 2012. Para ello el canal se dividió en cuatro secciones, dos iniciales cercanas al mar y dos finales cercanas a la laguna. Se realizaron 112 censos visuales mediante buceo libre. Para caracterizar el hábitat se midieron el área de refugio, sombra, temperatura del agua, salinidad, profundidad y velocidad de la corriente. Se determinaron la distribución espacio-temporal de los peces, riqueza de especies, densidad y frecuencia relativa en cada sección y se relacionaron con las características del hábitat. Se registraron 22 especies de peces distribuidas en 14 familias. Las especies Abudefduf saxatilis, Halichoeres bivittatus, Stegastes leucostictus y Lutjanus griseus fueron dominantes. Se encontró que las densidades y riquezas de peces en el inicio del canal eran más altas que en el extremo, particularmente la especie Lutjanus griseus, la cual cambió sus preferencias de nichos, desde el final del canal hacia el inicio. Se encontró que las comunidades de peces variaron espacial y temporalmente. El proceso de restauración produjo una disminución en la disponibilidad de refugios y, en consecuencia determinó la disminución de la densidad y riqueza de especies solo en el canal de entrada a la laguna. Los cambios más drásticos en el patrón espacial y temporal de los peces estuvieron asociados a las secciones finales del canal, las cuales sufrieron las mayores alteraciones de hábitat.

Interactions of natural and sexual selection: damselfish prioritize brood defense with male–male competition or courtship

Natural and sexual selection often act in opposing directions, forcing individuals to prioritize activities necessary for survival with those required for reproduction. We examined the interaction of natural and sexual selection pressures on the behaviour of beaugregory damselfish, Stegastes leucostictus, by presenting territorial males with an egg predator and either a male or female conspecific, requiring males to prioritize brood defense with either courtship or intra-sexual competition. By measuring the time spent near stimuli, we examined the influence of several factors, including stimuli type, variation in predator number, and the presence of eggs in a nest site. Generally, males spent more time with conspecific stimuli than egg predators, suggesting that the sexual selection pressures of deterring rivals and attracting mates outweigh the natural selection pressure to engage in brood defense. This decision was affected by the sex of the conspecific presented, the presence of eggs in a male's territory, and a number of interactions of these factors, indicating that male damselfish consider multiple factors before investing in certain types and intensities of behaviours. Furthermore, observations of behaviours associated with courtship and intrasexual aggression show that a natural selection pressure impacts intra- and inter-sexually selected behaviours differently in this system.

Assessment and decision-making in a Caribbean damselfish: nest-site quality influences prioritization of courtship and brood defence

In systems where territory quality varies, animals are expected to exhibit plasticity in behaviour in order to maximize fitness relative to their present territory quality. This requires assessment of territory quality followed by decision-making in relation to the priority of activities necessary for survival and reproduction. We examined how differences in territory quality of beaugregory damselfish ( Stegastes leucostictus ) influence the prioritization of courtship and egg defence by comparing behavioural responses of males defending artificial sites (high quality) with males defending natural sites (low quality) when presented with an egg predator, a conspecific female, and a simultaneous choice between both. A significant three-way interaction of territory quality, presentation type and stimulus was observed for time near stimuli. In paired presentations, males defending low-quality territories spent more time near a female and less near an egg predator; while males on high-quality territories spent more time near a predator than a female. Additionally, comparing single and paired presentations reveals that behaviours towards egg predators remain constant while behaviours towards females decrease with paired stimuli. These data suggest that territory quality and ecological context impact decision-making and the relative values of potential reproduction and/or past reproductive effort.

New insights into neuropeptide modulation of aggression: field studies of arginine vasotocin in a territorial tropical damselfish

The neuropeptides arginine vasotocin (AVT) and arginine vasopressin are key modulators of affiliation and aggression among non-mammalian and mammalian vertebrates, respectively. Here, we explored AVT's effect on aggression in a wild population of beaugregory damselfish, Stegastes leucostictus , a highly territorial species. Aggression by territorial males towards ‘intruders’ (bottled fishes) was assessed before and after each male received intramuscular injections of either AVT, Manning compound (an AVT V1a receptor antagonist), isotocin (the teleost homologue of mammalian oxytocin differing from AVT by two amino acids) or saline (vehicle control). Compared to saline controls, AVT and Manning increased and decreased aggression, respectively, while isotocin had no effect. Response selectivity was further established in a dose–response study that revealed an inverted U-shaped function. Compared to saline controls, aggression levels for low and high AVT doses were similar, while medium dose treatments were significantly greater. This type of behavioural response, the first that we know of for a vertebrate neuropeptide, could depend on the binding of AVT to both V1-type and other AVT or non-AVT receptors. The pattern revealed here for damselfish may be symptomatic of species- and context-dependent specificity of AVT's modulation of aggression across teleosts, as is currently proposed for tetrapods.