Parablennius Sanguinolentus Research Articles

Molecular validation of the specific status of <i>Parablennius sanguinolentus</i> and <i>Parablennius parvicornis</i> (Pisces: Blenniidae)

Parablennius sanguinolentus and P. parvicornis have been classified as either two distinct species or as two sub-species depending on the different criteria used to classify them. An analysis of fragments of mitochondrial 12S and 16S rDNA showed that the genetic distance between samples of P. sanguinolentus and P. parvicornis is similar or higher than those found for other blenniids that are widely recognized as distinct species. These results, together with the distinct geographical distributions and meristic differences, support the conclusion that P. sanguinolentus and P. parvicornis should be considered as two different species.

Male Sexual Polymorphism, Alternative Reproductive Tactics, and Androgens in Combtooth Blennies (Pisces: Blenniidae)

In species in which intense intermale competition for the access to females is present males of lower competitive ability may adopt alternative reproductive tactics (ART) to get access to mates. These ART translate in many cases into male sexual polymorphism, with individuals following distinctly different tactics. Usually two alternative male morphs can be recognized in species with ART: (1) bourgeois males that compete for access to mates invest in typically male behaviors, such as building elaborated nests or displaying ornaments; and (2) parasitic males that take advantage of the success of the bourgeois males in attracting females and attempt “sneaker” fertilizations (e.g., sneaker and satellite males). In combtooth blennies (Blenniidae) the co-occurrence of ART and male sexual polymorphism has been described for two temperate species: the peacock blenny, Salaria pavo, and the Azorean rock-pool blenny, Parablennius sanguinolentus parvicornis. Interestingly, while in the peacock blenny the alternative male morph adopts a sneaker tactic, in the rock-pool blenny parasitic males act as satellites to nest-holder males. Thus, this variation in the ART expressed in these two closely related species allows for a comparative study of the proximate and ultimate factors affecting the expression of the two ART. In this article we summarize the available information on androgen levels in bourgeois and parasitic males of natural populations of the two species and of recent studies on the effect of exogenous administration of androgens on tactic switching in parasitic males of the two species. The information is discussed within the frame of the relative plasticity hypothesis, which predicts that plastic alternative morphs should show differences in hormone levels and that the administration of sex steroids should be effective in promoting the switch from the parasitic to bourgeois tactic. The evidence is only partly consistent with this hypothesis. Alternatively, a social transduction hypothesis that better fits the available data on androgens and ART in teleost is proposed. It states that the observed differences in androgen levels between alternative morphs should not be interpreted as an organization vs activation effect of steroids, but rather as the limited vs lifelong responsiveness of the neuroendocrine axis to social regulation.

Gonadal investment of young males in two blenniid fishes with alternative mating tactics

The males of two blenniid species which exhibited alternative life history tactics and matured in their first year of life varied in size distribution within the age class and in behaviour. Salaria pavo were the smaller fish of the age class and behaved as sneaker males whereas Parablennius sanguinolentus parvicornis were the larger fish and behaved as satellites.

Effects of Androgens on Social Behavior and Morphology of Alternative Reproductive Males of the Azorean Rock-Pool Blenny

In the Azorean rock-pool blenny Parablennius sanguinolentus parvicornis two sequential reproductive tactics occur. Larger and older males establish breeding territories, while some of the smaller males become attached to nest-holder territories, acting as satellites on these territories, which they help to defend while trying parasitic fertilizations when females go in the nests to spawn. In the present paper we tested the effects of the androgens 17α-methyltestosterone (MT) and 11-ketotestosterone (KT) in the expression of male secondary sex characters and bourgeois behavior in satellite males. One week after satellites were implanted with Silastic tubes containing MT, KT, or castor oil (control), androgen-treated satellites had developed male secondary sex traits such as longer and wider male-type genital papilla and anal glands that secrete a sex pheromone, both traits being less expressed or absent, respectively, in satellite males. Androgen treatment had no effect on the gonadosomatic index or on the development of the testicular gland. KT treatment had a positive effect on relative liver weight. In terms of behavior, androgen-implanted individuals were less aggressive both in a mirror test and toward females when these were introduced into their tanks. MT-treated individuals spend more time inside the provided nests. Only androgen-implanted satellites managed to have the females entering their nests. When given a chance in a group tank either to try to attract females to their own nest or to act as satellites of an already established nest-holder's nest, MT-implanted males spent significantly more time in their own nest than near the nest-holder nest. These data suggest that androgens, particularly testosterone, may be involved in mating tactic switching in this species.

Male mating success in the Azorean rock-pool blenny: the effects of body size, male behaviour and nest characteristics

Larger male Azorean rock-pool blennies Parablennius sanguinolentus parvicornis received more female visits, were courted more often by females and received more spawnings. Larger males also received a higher number of male intrusions, attacked more conspecifics and defended larger territories. Larger males showed more nest cleaning behaviour and a marginally non-significant trend for higher egg fanning rate. Male courtship, male attack rate against conspecifics and parental behaviour were all correlated with the frequency of female spawnings received by each male even when controlling for male size, suggesting that these behaviour patterns influence male mating success. On the other hand, a positive partial correlation was found between female courtship and the frequency of female spawnings, controlling for the number of female visits, which suggests a role for female mate choice on male mating success. Finally, males nesting in chambers in the bottom of pools received more spawnings than males nesting either in crevices or under boulders. However, nest opening area was associated significantly negatively with male mating success, when controlling for male size. Thus, the present data suggest strongly that male characteristics overrule nest characteristics in determining male mating success in the Azorean rock-pool blenny.

Effects of Salinity on Survival, Osmoregulation, and Oxygen Consumption in the Intertidal Blenny, Parablennius sanguinolentus

were collected in the eastern coast of the Mediterranean (Israel) and acclimated to three salinities: full strength seawater (36.0 ppt), 40% seawater (14.4 ppt), and freshwater (< 1.0 ppt) for four weeks. Survival in 40% seawater was similar to seawater (94.4 ? 4% and 88.4 ? 4%, respectively), and both were significantly higher than in freshwater (8.0 ? 3.7%). Total body water content was 78.0 ? 0.4% in seawater, significantly lower than in 40% seawater (80.2 ? 0.2%), and both were significantly lower than in freshwater (82.6 ? 0.3%). Hematocrit also significantly differed among salinities (0.36 ? 0.01, 0.33 ? 0.01, and 0.30 ? 0.02 in seawater, 40% seawater, and freshwater, respectively). Plasma osmolarity (413.0 ? 7.2, 346.2 ? 5.1, and 270.9 ? 10.2 mOsmol) and plasma Na+ concentrations (198.1 ? 3.0, 166.3 ? 2.5, and 129.3 ? 4.7 mmol) also differed among salinities (seawater, 40% seawater, and freshwater, respectively). Standard metabolic rates of P sanguinolentus were similar in seawater and 40% seawater but significantly lower in freshwater. The results suggest low salinity tolerance and osmoregulatory capabilities in comparison to other blennies.

Reproductive phenology of the Azorean rock pool blenny a fish with alternative mating tactics

Both male and female Parablennius sanguinolentus parvicornis were ready to mate by the end of May. Seventy‐five per cent of the 1‐year‐old males were mature, but only 25% of the females reached maturity at this age. In females, gonads formed an increasingly greater proportion of the total weight with age, but in males the proportion decreased. A bimodal distribution of gonadosomatic indices classes was observed in 2‐year‐old males (intermediate size), which reflected the lower opportunity that intermediate size males have to spend the ejaculates than have the younger and older males. The liver played an important role in the storage of energy before the reproductive season and reserves were utilized during the breeding season. Physical condition was at its lowest in July in both sexes, but in May, just before the breeding season began, large maturing females had significantly lower eviscerated condition than males. This could be due to females investing in oocyte development, while the priority for the males was to reserve their energy for the parental activities to come. In both males and females, older and bigger animals had lower hepatosomatic and body conditions than younger ones.

Seasonal Variations of Injuries Suffered by Individuals of the Azorean Rock-Pool Blenny (Parablennius sanguinolentus parvicornis)

Seasonal Variations of Injuries Suffered by Individuals of the Azorean Rock-Pool Blenny (Parablennius sanguinolentus parvicornis)

Age, Growth and Sex Ratio of the Azorean Rock-Pool Blenny, Parablennius Sanguinolentus Parvicornis

The age and population structure of Parablennius sanguinolentus parvicornis (Valenciennes) (Pisces: Blenniidae) from the Azores have been studied. Total length and weight relationships are given for each sex. Age study was based on otoliths readings. The von Bertalanffy growth function was applied to describe the growth in total length with age. At the end of the first year mean (±SD) total length was significantly different in males (7.1 ±1.5 cm) and females (6.1 ±1.2 cm). One-year-old males participate in reproduction as satellites, whereas females do not. The implications of this in early growth rate of the males is discussed. During the two most important months of the reproductive season (i.e. June and July), the sex ratio was significantly biased towards males, particularly in the larger size classes.

On the Occurrence of Parablennius Sanguinolentus (Pisces: Blenniidae) on the Portuguese Coast

In this paper we report for the first time the occurrence of Parablennius sanguinolentus in mainland Portuguese waters. Since this species is common in the Mediterranean and in the Bay of Biscay, there appears to be a distributional gap along the Portuguese coast. The present finding, together with recent data on the occurrence of several other blenniids in the Atlantic coast of the Iberian Peninsula, formerly supposed to be Mediterranean endemics, stresses the urgent need for detailed zoogeographical investigations on the inshore fish fauna of south-west Europe.Parablennius sanguinolentus (Pallas, 1811) is widespread in the Mediterranean (Zander, 1986). On the Atlantic coast of Europe, however, it was known only from the Bay of Biscay where it is abundant in some places (Motos &amp; Ibañez, 1979), from the north-west coast of Spain (Devesa et al., 1979) and recently from the Atlantic coast of Andalucía (Spain) (Rubio, 1991). It is also very common in the Azores, Madeira and Canary Islands if one assumes that P. parvicornis (Valenciennes, 1836) belongs to the same species, but this is as yet an unresolved issue (Zander, 1979; Almeida &amp; Harmelin-Vivien, 1983; Bath, 1990; Santos, 1992). Although Zander (1986) presented a distributional map that includes the mainland Portuguese coast, no report on the occurrence of this species was known for this area. In a survey of the literature on the blennioid fishes occurring in Portuguese waters, we could not find a single citation that could possibly be ascribed to P. sanguinolentus for mainland Portugal (Oliveira et al., 1992).