Sexual development and reproductive seasonality of hogfish (Labridae: Lachnolaimus maximus), an hermaphroditic reef fish

The seasonality, size, age, colour phases and sexual dimorphism of 13 reproductive classes of hogfish Lachnolaimus maximus are described. Analysis of histological sections of gonads ( n = 1662) confirmed earlier conclusions that L. maximus is a monandric, protogynous hermaphrodite. Sex change was initiated at the end of the spawning season and over a broad range of sizes and ages. It occurred after a functional female phase (postmaturation) and proceeded more slowly (months) than previously believed. Eventually all individuals changed sex to a terminal male phase. Females were batch spawners, spawning as often as every day during winter and spring. There was no evidence of precocious sperm crypts in active females, sperm competition or other alternative male sexual strategies. Mating has been reported elsewhere to be haremic. The sexual development of L. maximus appears to be adaptive in terms of Ghiselin's size-advantage model, which links monandric protogyny and polygyny. The slow rate of sex change, however, poses problems when fishing pressure is high because harvest of a single male has the potential to reduce the reproductive output of an entire harem.     

Hogfish Lachnolaimus maximus (Labridae) confirmed in the south‐western Atlantic Ocean

Based on material deposited in collections, photographic records and other reports from fishermen and divers, the occurrence of the hogfish Lachnolaimus maximus (Labridae) is confirmed in the south‐western Atlantic Ocean, near the Brazilian coast as far south as southern Brazil. The recognized range of this species should therefore be extended c. 3000 km further south.     

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     

Home range areas and activity centres in six species of Caribbean wrasses (Labridae)

In six Caribbean wrasse (Labridae) species: Halichoeres bivittatus , Halichoeres garnoti , Halichoeres maculipinna , Halichoeres poeyi , Halichoeres radiatus and Thalassoma bifasciatum , home range area ( A _HR) was positively correlated with fish total length ( L _T) and this relationship was not significantly different among H. bivittatus , H. garnoti , H. radiatus and T. bifasciatum . The data for three of these species ( H. radiatus was excluded because only juveniles were investigated) were pooled and the relationship between L _T and A _HR was analysed for juveniles and initial phase (IP) adults separately. This analysis found that once individuals of these two species become IP adults, the A _HR reached a plateau, despite continued fish growth. In a separate analysis including all six wrasse species, after accounting for differences in L _T using ANOVA, it was found that IP adults required larger areas than juveniles, and terminal phase (TP) adults required larger A _HR than IP adults. Upon analysis of the distribution of activity throughout A _HR for all species studied, it was found that 50% of the observation points (defined as the activity centre) were found in 13 to 24% of the A _HR.     

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.     

Structure of the parasite communities of a coral reef fish assemblage (Labridae): testing ecological and phylogenetic host factors

The role of ecological and phylogenetic processes is fundamental to understanding how parasite communities are structured. However, for coral reef fishes, such information is almost nonexistent. In this study, we analyzed the structure of the parasite communities based on composition, richness, abundance, and biovolume of ecto- and endoparasites of 14 wrasse species (Labridae) from Lizard Island, Great Barrier Reef, Australia. We determine whether the structure of the parasite communities from these fishes was related to ecological characteristics (body size, abundance, swimming ability, and diet) and/or the phylogenetic relatedness of the hosts. We examined 264 fishes from which almost 37,000 individual parasites and 98 parasite categories (types and species) were recorded. Gnathiid and cestode larvae were the most prevalent and abundant parasites in most fishes. Mean richness, abundance, and biovolume of ectoparasites per fish species were positively correlated with host body size only after controlling for the host phylogeny, whereas no such correlation was found for endoparasites with any host variable. Because most ectoparasites have direct transmission, one possible explanation for this pattern is that increased space (host body size) may increase the colonization and recruitment of ectoparasites. However, endoparasites generally have indirect transmission that can be affected by many other variables, such as number of prey infected and rate of parasite transmission.     

Ecophenotypic physiology: osmoregulation by fiddler crabs (Uca spp.) from the northern Caribbean in relation to ecological distribution

Nine species of Uca were collected across the northern Caribbean from 50 locations ranging in habitat osmolality from 18 to 2760?mmol?kg^?1 (mosmol). The osmoregulating ability of each species was assessed in solutions ranging from 30 to 3550?mosmol. Survivorship, lower and upper median lethal concentration and haemolymph isosmotic concentration ([ISO]) were estimated for each. A lower lethal concentration could not be calculated for some due to survival in low osmolality. By subgenus, average [ISO] for four species from the subgenus Minuca ranged from 587 to 768?mosmol and three species from the subgenus Leptuca from 805 to 881?mosmol. For species from the subgenus Boboruca and the subgenus Uca the [ISO] was 805 and 930?mosmol, respectively. These values reflect the habitat preference of each species in a subgenus. This study broadens our understanding of ecological physiology in Caribbean Uca and demonstrates intra- and inter-specific differences among tropical fiddler crabs.     

Food habits of the giant humphead wrasse,Cheilinus undulatus (Labridae)

Synopsis The giant humphead wrasse (Cheilinus undulatus), an inhabitant of coral reefs, is widely distributed in the tropical Indo-Pacific region. Stomach and intestinal contents of 72 specimens from the Pacific and the Red Sea revealed that this fish feeds primarily on mollusks, fishes, echinoids, and crustaceans.This article is one of several presented at the Second European Ichthyological Congress, Paris, 8-15 September 1976, to be published by Environmental Biology of Fishes.     

Cleaning behaviour of the goldsinny (Pisces,Labridae) in Swedish waters

The goldsinny, $\text{Ctenolabrus}$$\text{rupestris}$, on the Swedish west-coast has been shown to be a facultative cleaner with the ballan wrasse, $\text{Labrus}$$\text{berggylta}$, as the cleanee. Twenty-four cleanings were observed during 1975 to 1981. The cleaning pattern of the symbiosis is described and the low rate of cleaners within the species is discussed.     

Distribution of behaviours and species interactions within home range contours in five Caribbean reef fish species (Family Labridae)

Synopsis This study investigated the distribution of behaviours and species interactions within home range contours in five Caribbean labrid species: Halichoeres bivittatus, H. garnoti, H. maculipinna, H. poeyi, and Thalassoma bifasciatum. For this study, contours were defined as: (a) 30%—the core use area, (b) 30–75%—the intermediate activity area, and (c) 75–95%—the peripheral activity area. Behaviours analyzed for this study included: (i) feeding (=biting the substrate or chewing), (ii) chased by pomacentrids, (iii) swimming alone, (iv) swimming with other fishes, and (v) all activities with other fishes. Fifty-nine percent of Halichoeres bivittatus observed showed a higher frequency than expected being chased by pomacentrids in the peripheral region of their home ranges. Halichoeres garnoti showed a lower frequency than expected swimming with other individuals in their core use area, and 64% of the individuals observed showed a higher frequency than expected being chased by pomacentrids in the peripheral region. In general, H. maculipinna exhibited a random distribution of behaviours throughout their home range areas, with a non-significant trend for more agonistic interactions with pomacentrids in peripheral regions. Halichoeres poeyi and T. bifasciatum showed higher frequencies than expected being chased by pomacentrids in the peripheral regions. Overall, the non-random distribution of agonistic interactions with pomacentrids throughout home range areas suggests that the presence or prior residence of territorial pomacentrids on coral reefs may modify the post-settlement selection of home range areas by these labrid species.     

Frequent visits to various anvils during tool use by the graphic tuskfish Choerodon graphicus (Labridae)

This study investigated tool use by the graphic tuskfish Choerodon graphicus in New Caledonia. Anvils included rocks, a conical shell, flat dead corals and a concrete mooring. Sixteen tool-use events were observed in 10 h. A tool-use event often involved more than one anvil (44%). On average, C. graphicus struck prey six times and spent 84 s at an anvil. The only prey items brought to anvils were bivalve and gastropod molluscs. These results provide a foundation for future research on tool use in fishes.     

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.     

Organization of the male gonad in a protogynous fish,Thalassoma bifasciatum (Teleostei: Labridae)

Although the testis in teleosts has been investigated for many years, little attention has been paid to the structure of the outer layers that enclose the testis and to their possible contributions to its organization. The present study in a protogynous male labrid, Thalassoma bifasciatum (bluehead wrasse), describes the arrangement and cytology of these tissues (for convenience, referred to collectively as the outer wall, OW) which include: the outer peritoneal layer and subjacent collagen fibers, myoid cells and diverse other cells and tissues, e.g., fibrocytes, presumptive mesenchyme, macrophages, granulocytes, nerves, and blood vessels. Beneath the OW are two compartments; one is the gamete-laden spermatocysts, the other the interstitium, which is composed of cells and tissues that lie between the spermatocysts. Both OW and interstitium contain similar kinds of tissues and cells. Moreover, the layers of the OW immediately subjacent to the peritoneum are continuous with that in the interstitium. It is suggested that the continuity between these two areas provides opportunities for the exchange of cells that could aid in the maintenance and reorganization of the testis and with the myoid and neural tissue to establish an extensive, coordinated motile system that aids movement of sperm from spermatocysts to the ducts. A recent report on the reexamination of the germinal epithelium concept and its identification in the common snook, Centropomus undecimalis, stimulated us to examine the feasibility of applying this concept to gonad organization and gamete development in T. bifasciatum. In addition, the ultrastructure of the Sertoli cell and formation of spermatocysts are described. Spermatocysts increase in size during the development of gametes. Observations and discussion are presented suggesting how Sertoli cells may accommodate this growth and how new populations of these cells may arise in the mature adult. Finally, ultrastructural characteristics for each stage of spermatogenesis are presented and, using (3H)thymidine and autoradiography, data on the chronology of spermatogonia-sperm cycle are included.     

Photoperiod, follicle-stimulating hormone receptors, and testicular function in vizcacha (Lagostomus maximus maximus)

In the present work we investigated the presence of testosterone in serum and follicle-stimulating hormone (FSH) receptors in testes of the vizcacha (Lagostomus maximus maximus), a South American rodent. We also investigated the effect of constant light on both parameters. The control group consisted of vizcachas caught in their natural habitat and maintained under continuous darkness; the experimental group consisted of animals maintained under constant light (1076 lx) for 8 days. The results revealed a significant decrease in serum testosterone and FSH receptors when the animals were maintained under constant light, as compared to the control group. Androstenedione was elevated in the serum obtained from the experimental group. It is postulated that the pineal gland may regulate testosterone secretion through FSH receptors and through an enzymatic blockade in the steroidogenic pathway; this supposition, however, remains to be proved.     

Goliath grouper Epinephelus itajara (Teleostei: Serranidae) in the Mexican Caribbean: local ecological knowledge and habitat use

Environmental Biology of Fishes - Rare species necessitate alternative survey techniques and, in the case of exploited resources, any attempt to monitor their abundance with a meaningful benchmark...     

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.     

Genetic identification of bucktooth parrotfish Sparisoma radians (Valenciennes, 1840) (Labridae,Scarinae) by chromosomal and molecular markers

Parrotfishes (Labridae, Scarinae) comprise a large marine fish group of difficult identification, particularly during juvenile phase when the typical morphology and coloration of adults are absent. Therefore, the goal of this study was to test cytogenetic markers and DNA barcoding in the identification of bucktooth parrtotfish Sparisoma radians from the northeastern coast of Brazil. Sequencing of cytochrome c oxidase subunit I (COI) confirmed all studied samples as S. radians, and all showed high similarity (99–100%) with Caribbean populations. The karyotype of this species was divergent from most marine Perciformes, being composed of 2n = 46 chromosomes. These consisted of a large number of metacentric and submetacentric pairs with small amounts of heterochromatin and GC-rich single nucleolar organizer regions (NORs) not syntenic to 5S rDNA clusters. These are the first data about DNA barcoding in parrotfish from the Brazilian province and the first refined chromosomal analysis in Scarinae, providing useful data to a reliable genetic identification of S. radians.