Karyological studies inCoris julis (Pisces,Labridae)

In the present investigation the diploid number 2n=48 (NF=58) has been determined for females, primary males, and secondary males ofCoris julis from the Gulf of Palermo. Differentiated sex chromosomes have not been observed in the population under study.     

Chromosomal analysis of repeated DNAs in the rainbow wrasse Coris julis (Pisces, Labridae)

Despite the interest of several authors, the karyotype of the labrid C. julis is still debated and in particular the presence of sex-chromosomes is still contradictory. In order to analyze the karyotype organization of C. julis we have performed an analysis with classical and molecular cytogenetic techniques. Our results after silver-, CMA₃- and DAPI-staining, C-banding and fluorescent in situ hybridization (FISH) using 28S rDNA, 5S rDNA, and telomeric repeat (TTAGGG) _n as probes allowed us to characterize the chromosomal location of several repetitive DNAs of C. julis. Finally, regardless of the technique used, no difference in the chromosome complement was found between males and females. This revised version was published online in August 2006 with corrections to the Cover Date.     

Courtship and Spawning Behavior in the California Sheephead, Semicossyphus Pulcher (Pisces: Labridae)

We recorded the courtship and spawning behavior of a protogynous fish, the California sheephead, Semicossyphus pulcher, throughout their spawning season at Bird Rock, Santa Catalina Island, California. We made additional observations at the Monterey Bay Aquarium and confirmed the details of behavior seen in the field. Large males held spawning territories in which females congregated approximately 1 h before sunset. Courtship commenced shortly before sunset and involved the male approaching each female, making lateral contact and leading her in a circular pattern. Smaller males attempted to court females within the territories, prompting large males to abort spawns and engage in chasing behavior with small males. Females visited several territorial males throughout the day, indicating that they are not part of a strict harem. Both field and aquarium observations confirm that the mating system can be successfully predicted from the size advantage model. Current regulations on the sheephead fishery, which allow for the removal of large, rare males, could have significant effects on the social structure, reproductive output, and mating processes of local populations. Moreover, understanding the mating system of the California sheephead illustrates the need for creating management strategies that better complement the unique life histories of marine fishes with alternative reproductive strategies.     

Benefits of heterospecific foraging by the Caribbean wrasse,Halichoeres garnoti (Pisces: Labridae)

Synopsis Terminal-phase yellowhead wrasses, Halichoeres garnoti, foraged alone or in association with foraging goatfish, Pseudupeneus maculatus and Mulloides martinicus. Whereas H. garnoti did not dig for benthic infauna, the goatfish foraged almost exclusively on and in sand substrata. Wrasses in the company of goatfish made significantly more strikes on sand substrata than did solitary wrasses, although there were no significant differences in the frequency of strikes on sand and hard substrata combined. The frequencies of other behaviors (searches, scratches, flights, chases, rests, yawns, and cleanings) were not significantly different between solitary and associated wrasses. H. garnoti are attracted to foraging goatfish, which provide access to an otherwise unavailable food resource. To whom reprint requests should be sent     

The feeding strategies of a facultative cleanerfish, Thalassoma bifasciatum (Pisces: Labridae)

The adult Bluehead wrasse (Thalassoma bifasciatum) is a facultative cleanerfish that can change its colouration into any one of three: patterns. These patterns correspond to several modes of feeding behaviour which, in turn, can be correlated with the movements of host fishes. The barred pattern occurred on individuals that are far ranging and also on those that formed unstable cleaning groups. These groups tended to form at locations having sharp drops in depth of several metres. Here these groups serviced large groups of host fishes. The striped pattern occurred on solitary individuals with a limited home range. They occurred in very shallow areas and serviced small groups of host fishes. The bright yellow pattern developed when a large food source was discovered and may be related to the attraction of conspecifics.     

The Lek-like Mating System of Halichoeres melanochir (Pisces: Labridae) at Miyake-jima,Japan1

Reproductive behavior and social organization of the labrid fish Halichoeres melanochir were studied at Miyake-jima, Izu Islands, Japan. ♂♂ set up contiguous territories from early to mid-afternoon daily during the breeding season, with ♂♂ at the center of the spawning site experiencing significantly higher spawning success than those at the periphery. Unlike other labrids with lek-like mating systems previously reported, H. melanochir is sexually monochromatic and shows only minimal sexual size-dimorphism. The spawning behavior and mating system are described and compared with current theories on labrid reproductive strategies.     

The distribution, age and growth of wrasse (Labridae) in inshore waters of west Scotland

Wrasse were widely distributed in inshore waters of west Scotland in rocky and algal habitats. Ctenolabrus rupestris and Centrolabrus exoletus dominated commercial and experimental catches using creels, traps and fyke nets, but Crenilabrus melops, Labrus bergylta and L. mixtus were infrequent. Maximum age of sampled fish was 16yr in C. rupestris , 9 yr in C. exolefus , 5 yr in C. melops , 15 yr in L. bergylta , and 11 yr in L. mixtus . Growth was more rapid prior to maturation in all species. The von Bertalanffy growth model fitted data for C. rupestris and C. exoletus . Male C. rupestris and C. exoletus were significantly longer than females in most age groups and growth of all species captured in mid–Scottish areas was more rapid than in northern localities. Mortality (Z) of C. rupestris was 0–1861 per year and 0·4185 in C exoletus .     

Sex-dependent synaptic behaviour in triploid turbot,Scophthalmus maximus (Pisces,Scophthalmidae)

A surface-spreading synaptonemal complex (SC) technique was used to analyse spermatocytes and oocytes of triploid turbot (Scophthalmus maximus) in order to visualise the process of chromosome synapsis. The most conspicuous characteristic of triploid oocytes is that, in the trivalents, the lateral elements of the SC were frequently associated in threes, either completely along the length of the trivalent, or partially, forming a variety of forked structures. In these nuclei, synapsis usually occurred among homologous chromosomes and the number of bivalents observed was significantly higher than that expected under the assumption of random chromosome association among all partners. However, the frequency of trivalents was very low in triploid spermatocytes, triple synapsis being also scarce. In these nuclei chromosomes that were excluded from homologous synapsis become engaged in random SC formation, and, therefore a considerable number of non-homologous associations are produced. The causes of the synaptic differences observed in triploid males and females of turbot and their possible relation to the sterility displayed by these animals are discussed.     

The reproductive behaviour ofAequidens vittatus (Pisces,Cichlidae) in Surinam,South America

Synopsis The behaviour of free-living pairs ofAequidens vittatus was observed in Surinam, South America. An ethogram of breeding behaviour is presented, based on those observations and on aquarium-held fish. This is a biparental, substrate-guarding species that spawns on a movable platform. Sexual differentiation of parental roles was more pronounced when the young were in the embryonic interval than when they were mobile juveniles. Females spent more time near their brood, attacked juvenile conspecifics more often, and fanned and mouthed embryos more than males did. Males were more involved than females in territorial spacing of pairs. The movable spawning leaf provides support for eggs on detritus substrate and may also provide protection against predators and rapid water level changes.     

Spatio-temporal patterns of recruitment of labroid fishes (Pisces: Labridae and Scaridae) to damselfish territories

Recent studies have shown that recruitment variability is an important process structuring reef fish assemblages. The aim of this study is to describe the spatio-temporal patterns of recruitment of three abundant labroid taxa (Coris schroederi, Halichoeres melanurus and Scarus spp.), using damselfish territories as replicate units of habitat. Temporal recruitment patterns of each taxa were consistent among three sites along 2 km of reef tract, with small differences among sites probably the result of hydrological or random factors operating at that scale. Recruitment of only one species (C. schroederi) showed consistent differences in the magnitude of recruitment among sites, which was probably due to an overriding effect of habitat selection for the location of the territories on the reef profile at one site. Two taxa, C. schroederi and Scarus spp., recruited in low to moderate rates over many weeks with moderate recruitment peaks detected in one year only. This pattern may be characteristic of many labroid species that have protracted periods of production of larvae. In contrast, H. melanurus recruited in a single short pulse of high magnitude each summer, which suggests that production of larvae by this species may occur over a more restricted period of time. No strong pattern of lunar entrainment of recruitment was detected for any taxa, which may be due to a lack of lunar periodicity in production of larvae. Further studies are now required to identify the processes that are important in determining patterns of labroid recruitment. This revised version was published online in August 2006 with corrections to the Cover Date.     

Territoriality and reproductive behaviour in the goldsinny, Ctenolabrus rupestris L.

Territoriality and reproductive behaviour of the Goldsinny, Ctenolabrus rupestris, was studied in the waters around Tjärnö on the Swedish west coast. Observations were made by SCUBA-diving and from an observation raft and in aquaria.Patrolling, foraging, courtship and aggression were defined and quantified throughout the reproductive season and after. Spawning activity was also examined and it has been found that one male spawns with several females. During spawning accesory males may be present at fertilisation and their role is discussed. Both sinking and floating eggs were recorded, which are discussed.After spawning some females became territorial as well as some subadults. The territories showed a consistency according to their boundaries and occupants from year to year.     

The ontogeny of agonistic behaviour in the blue gourami, Trichogaster trichopterus (Pisces,Anabantoidei)

The development of agonistic behaviour in the blue gourami, Trichogaster trichopterus, was studied from hatching to four months of age. Larval motor patterns appear first as simple, uncoordinated, and irregular movements and gradually become regular and well coordinated, forming integrated complex patterns, such as swimming, surfacing, and feeding. Most motor patterns used in agonistic interactions are first exhibited in non-social contexts. Initial interactions between young fish consist of Approach and investigation in a feeding context, in some cases followed by nibbling, Biting, and Chasing by one fish. Later, initial Approaches are separated from Biting and Chasing by Lateral Displays, circling, Tail Beating, and Fin Tugging, and by Appeasement behaviour that inhibits Chasing and Biting by the opponent.Agonistic behaviour of socially isolated fish, when paired in dyadic encounters as adults, indicates that the role of social experience as an integrator and regulator of social behaviour may change progressively during development and become more important as ontogeny proceeds.     

The incidence of Livoneca sp. (Isopoda) on Helotes sexlineatus (Pisces) in Kuwait waters

Infestations of Livoneca sp. occur on the striped therapon, Helotes sexlineatus, in Kuwait waters. Infestation rate decreases as depth increases, and some infested fish were found in all samples examined; the occurrence of infested fish could not be used as a biological tag. One year and four year old fish were uninfested. Two and three year old fish showed different infestation rates (4.1% and 0.9 % respectively). No striped therapon carried more than one parasite.     

Patterns of abundance and size structure in the blue groper, Achoerodus viridis (Pisces, Labridae): evidence of links between estuaries and coastal reefs

Linkages between estuarine nursery areas and coastal reefs are thought to be important for sustaining populations of some reef fishes. Patterns of abundance and size structure in the blue groper, Achoerodus viridis (Pisces: Labridae), were documented at sites extending from sheltered reefs and seagrass, Zostera capricorni, habitats, in shallows of estuaries, to adjacent exposed reefs in New South Wales, Australia. Numbers of juvenile fish (< 200 mm SL) decreased from shallow to deep areas of reef within a site and from inner to outer estuarine sites within two estuaries. Increased numbers of large fish (> 400 mm SL) were found on the more exposed coastal reefs. These patterns were consistent over the 21/2 year study (May 1991–December 1993). Recruits were found in both seagrass and rocky reef habitat, and showed similar patterns of abundance to juveniles. Recruitment of A. viridis to seagrass habitat occurred in distinct seasonal pulses each year; peak recruitment occurred in September and October of each year. Patterns of abundance and size structure were consistent with a model of estuarine recruitment and movement to the open coast, but alternatives, such as differential mortality, could not be discounted.