Reproduction of the Nassau grouper,Epinephelus striatus (Pisces: Serranidae) and its relationship to environmental conditions

Synopsis Spawning aggregations of the Nassau grouper, Epinephelus striatus, occurring at the southern end of Long Island were investigated during the winters of 1987–1988 and 1988–1989. Fish aggregate at two specific sites around the time of the full moon in December and January, possibly not during November and almost certainly not during February. At one site the fish aggregate well inside the shelf edge while at the other they are on the dropoff into deep water. Fish migrate, probably as distinct groups of up to about 500 individuals, to the sites on or before the full moon and remain for several days. There was no significant difference in the size of males and females caught from the aggregations between years or months. Female/male sex ratio was between 5 : 1 and 3 : 1. Courtship occurred in late afternoon with spawning commencing shortly before sunset. Most spawning occurred within 10 min of sunset. Water temperatures were 25.0–25.5°C during a period of gradual decrease towards the annual minimum in February and March. Two color patterns were important in courtship and spawning. The bicolor pattern is a submissive coloration indicating a non-aggressive state acquired by both males and females near the time of spawning. The dark phase is acquired by females who are followed by numerous bicolor fish during courtship and they lead spawning events in this pattern. Spawning occurred among subgroups of the aggregation numbering 3–25 fish; gamete release was well above the bottom. Drogues deployed with the gametes either moved inshore or did not move far away from the shelf edge over the course of several days. Nassau groupers may not strictly be protogynous hermaphrodites and other groupers which form spawning aggregations may not be so either. Latitudinal shifts in spawning time may be related to water temperatures. Currents at aggregation sites do not appear to favor offshore transport of eggs. Questions of whether spawning aggregations should be protected need to be answered.     

Population variation in spawning current speed selection in the blacktail shiner,Cyprinella venusta (Pisces: Cyprinidae)

Synopsis Many stream fishes lay demersal eggs. Some species simply scatter the eggs across the substrate, but many place the eggs in protected sites such as crevices (e.g., Cyprinidae:Cyprinella). Eggs laid in crevices may experience increased development times or lower embryo survival due to reduced water exchange rates compared to more open egg deposition sites. If so, the presence of an appreciable current near the crevice may be important for insuring water exchange. However, currents that are too strong may prevent complete insemination or prevent the eggs from adhering to the substratum before they are washed from the crevice. Thus, current speed preferences for spawning may be under strong stabilizing selection. Representatives of four populations of a crevice spawning stream fish (blacktail shiner,Cyprinella venusta), representing environments ranging from a swift stream to a lake, were studied in stream tanks to evaluate female spawning current use. The observed frequency of use of spawning currents was significantly different from random in all populations. Low current speeds were generally avoided, and a speed of ca. 30 cm sec^–1 was used most often. However, significant differences were observed among populations, and the variation correlated well with the apparent range of current speeds found in the four environments. Although other possible explanations cannot be dismissed, the results are consistent with the hypothesis that the populations have become adapted to their local current regimes.Authorship in order of seniority     

Courtship and spawning behavior of the pygmy grouper,Cephalopholis spiloparaea (Serranidae: Epinephelinae), with notes on C. argus and C. urodeta

Synopsis Courtship and spawning behavior is described for the grouper Cephalopholis spiloparaea from Rota, Mariana Islands. Daily courtship behavior began late in the afternoon and proceeded until after sunset. Males repeatedly visited females in single-male, multiple-female mating groups during each period and engaged in courtship bouts. Mating was observed only twice, was paired and pelagic. Two congeners, C. argus and C. urodeta, with overlapping geographical distributions, were also examined. Cephalopholis urodeta appeared to have a mating group organization similar to that of C. spiloparaea, with some similarity in courtship behavior. Cephalopholis argus also had a similar mating group organization but differed in courtship behavior. This species' behavior more closely resembled that of similarity-sized Epinephelus spp.     

Hydroacoustics for the discovery and quantification of Nassau grouper (Epinephelus striatus) spawning aggregations

Coral Reefs - Fish spawning aggregations (FSAs) are vital life-history events that need to be monitored to determine the health of aggregating populations; this is especially true of the endangered...     

Experimental removal of piscivorous groupers of the genus Cephalopholis (Serranidae) from coral habitats in the Gulf of Aqaba (Red-Sea)

Synopsis Elimination of adult groupers (Cephalopholis spp.) from various reef formations in the Gulf of Aqaba (Red Sea) resulted in replenishment by other predatory fishes of different taxa and only partly (21.6%) by species of the same genus. Three years later, the initial population composition had not been restored. Recolonization by juvenile groupers presumably settling from the plankton was only 11.3%. Censuses of the typical piscine prey of groupers, before and 36 months after the removal of Cephalopholis, showed virtually no change in abundace and species composition.     

The courtship and spawning behaviors ofCanthigaster valentini (Tetraodontidae)

Synopsis The sharpnose puffer,Canthigaster valentini, occurs in male-dominated harems of territorial females at Lizard Island (Australia). Spawning occurs daily and year-round. Males only spawn with the females of their social group, inside the female's territory. Females signal their readiness to begin courtship with a display that exposes their egg swollen abdomen. Courtship is long and males do not develop specific courtship colors or perform unique displays. Eggs are fertilized in a demersal nest and there is no parental care.     

Semilunar spawning cycles ofFundulus similis (Cyprinodontidae)

Synopsis The longnose killifish,Fundulus similis (Cyprinodontidae), spawns with a semilunar periodicity during an extended breeding season (March through August) along the Alabama (U.S.A.) Gulf coast. Spawning characteristically occurs during the 3–6 days of the ascending and spring tides of each semilunar tidal cycle. Such spawning cycles appear to be a relatively common adaptation within the reproductive strategies of intertidal cyprinodontids.     

Reproductive behavior of the sergeant major,Abudefduf saxatilis,within a closed system aquarium

Synopsis The reproductive and social biology of the sergeant major,Abudefduf saxatilis, was studied for six months in The Living Seas aquarium (the largest aquarium ever constructed). The purpose of the study was to discern possible behavioral differences between captive and wild breeding populations of this species. A total of 350 h of observation were obtained using closed circuit SCUBA, open circuit SCUBA, and remote operated vehicles. Slight differences were observed in the behavior of individuals in the sample population and those seen in wild populations. These differences may be due to the effects of a controlled closed system on the biology of these fishes.     

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...     

Reproductive styles of shallow-water groupers (Pisces: Serranidae) in the eastern Gulf of Mexico and the consequences of fishing spawning aggregations

Synopsis Seasonal and spatial aspects of spawning for three commercially important grouper species in the northeastern Gulf of Mexico are detailed. These species — all of which are protogynous hermaphrodites - spawn in deep water (> 25 m for red grouper,> 40 m for gag and scamp), making it difficult to observe spawning behaviors without ROV or submersible support. They respond to intense fishing pressure in ways that are directly related to their respective reproductive styles. Species that aggregate appear to be more susceptible to such pressures than those that do not, as evidenced by marked skewing of sex ratios in favor of females. Gag, Mycteroperca microlepis, have suffered a drop in the proportion of males from 17% to 1% in the last 20 years; scamp, Mycteroperca phenax, have dropped from 36% to 18%; and red grouper, Epinephelus morio, which do not aggregate, have shown little change in the sex ratio over the past 25–30 years.     

Social organization and spawning in the Atlantic sharpnose puffer,Canthigaster rostrata (Tetraodontidae)

Synopsis Social organization and spawning in the sharpnose pufferCanthigaster rostrataere studied on a reef in the San Blas Islands, Panama. Sexes were dimorphic. In mixed coral and rubble habitat, females defended territories against other females and small males. From one to six female territories were included within the territories of certain large males. These haremic males visited their females and patrolled their territories throughout the day. Smaller, non-haremic males occupied territories or home ranges within or adjacent to those of haremic males or were wanderers. Spawning between a haremic male and a territorial female occurred within the female's territory. The female prepared an algal nest into which demersal eggs were deposited. There was no parental care. Eggs were spherical, translucent, and measured approximately 0.66 mm in diameter. Larvae were about 1.4 mm TL and closely resembled those of other species ofCanthigaster.     

Characterization of 12 microsatellite markers in Serranus cabrilla (Pisces: Serranidae)

The commercial comber Serranus cabrilla is widely distributed in the Atlanto‐Mediterranean region, inhabiting a great variety of habitats and depths. We developed primers for 12 polymorphic microsatellite loci to analyse the genetic structure between comber populations and between their colour morphs in order to establish correct fisheries management. Characterization of 25 individuals from Columbretes Islands (Spain) showed an average large number of alleles (9.5 ± 1.3) and observed heterozygosity (0.657 ± 0.06). Only two loci showed significant departure from Hardy–Weinberg equilibrium. We found no evidence of linkage disequilibrium between pairs of loci. We rejected for primer design one clone with a microsatellite within the transposable element TX_FR2.     

Mexican Blindcats Genus Prietella (Siluriformes: Ictaluridae): an overview of Recent Explorations

The ictalurid genus Prietella was described from a single locality in northern México (Coahuila) in 1954, and until very recently went largely unstudied. Cave explorers have recently uncovered new localities and a second species much farther to the south (México: Tamaulipas). Our team visited over 50 sites, including all of the previously known sites possible, and explored many new sites, expanding the known range of Prietella and describing their habitat. We identified geological units and mapped caves, identified associated troglobitic invertebrates, estimated population sizes and measured water chemistry parameters. We also comment on laboratory diet, parasites, sensory biology, behavior (such as jaw locking and periods of inactivity), reproduction and systematics based on preliminary genetic data. Prietella phreatophila is listed as endangered, and due to the recent discovery of many more sites (formerly documented from three localities, now known from twelve sites, though some are hydrologically connected) we recommend threatened status, with careful attention to growing threats such as over pumping and contamination of the aquifer it lives in. Should these patterns continue unchecked, re-listing this species as endangered may be called for. Prietella lundbergi was also described from one site but is now known from two, though it is quite rare at both (only five specimens have ever been seen). P. lundbergi was described after the most recent revision of the Mexican endangered species list and should probably be considered as endangered.     

The reproductive biology of closely related coral species: gametogenesis in<Emphasis Type="Italic"> Madracis</Emphasis> from the southern Caribbean

Reproductive patterns were studied in closely related coral species of the genus Madracis on Curaçao, Netherlands Antilles. Gonadal development of six sympatric species was examined over a 13-month period. Reproductive differences among Madracis species are small. All species are hermaphroditic brooders and show similar patterns in gamete development. Timing of gamete maturation is positively correlated with seawater temperature in all species. Oocyte development typically begins in June and precedes the development of spermaries. Mature gametes, male and female, are present from August to November when seawater temperatures reach their yearly maximum. Developmental pathways for male and female gametes are identical among species. Interspecific differences exist in the number and size of oocytes. Our data indicates that differences in gametogenic development between closely related, but ecologically different subspecies are small or absent and do not necessarily match with species separations based on morphological criteria.Communicated by Topic Editor D. Barnes     

Echinoderms (Echinodermata) of the Mexican Caribbean

A systematic list of the echinoderms of the Mexican Caribbean based on museum specimens of the Colección Nacional de Equinodermos, Instituto de Ciencias del Mar y Limnología, Universidad Nacional Autónoma de México and the National Museum of Natural History, Smithsonian Institution, Washington, D.C. is presented. This list reveals an important echinoderm biodiversity in the Mexican Caribbean, where five of the six echinoderm classes are represented. A total of 178 echinoderm species is recorded, distributed in 113 genera, 51 families and 22 orders. 30 new records for the Mexican Caribbean are presents: Crínoidea (three), Asteroidea (two), Ophiuroidea (eleven), Echinoidea (one), Holothuroidea (thirteen).     

Responses to light in two blind cave fishes (Amblyopsis spelaea and Typhlichthys subterraneus) (Pisces: Amblyopsidae)

Explanations for the phenotypical features resulting from colonization of subterranean environments have always been a source of controversy. Although a great number of cave organisms are blind, they nevertheless display responses to light. The interpretation of this phototactic responsiveness in cave-dwelling animals may provide clues on the general issue of evolution of behavior in parallel with specialized structures. We studied the phototactic responses in two amblyopsid fishes of North America and found responses to light only in the species reported to have a functional pineal organ. Our findings are consistent with the hypotheses that (1) adaptation to the cave environment is a gradual process and (2) responsiveness to light in cave fishes may best be understood as a relict character, one that exists in an environment where it may never be expressed.     

Field and laboratory observations of spawning periodicity and behavior of a northern population of the Atlantic silverside,Menidia menidia (Pisces: Atherinidae)

Synopsis The spawning periodicity and mating behavior of a northern population of the Atlantic silverside, Menidia menidia, was studied both in the field (Salem Harbor, Massachusetts) and in laboratory experiments. Spawning in the field coincided with new and full moons. Under conditions of unlimited food availability in artificial outdoor pools that received natural celestial illumination or in indoor aquaria receiving no evening illumination, spawning occurred every 1–3 days rather than fortnightly. These results suggest that tidal influences are a primary factor that synchronizes spawning in M. menidia. Published reports of diel time of spawning in both marine and freshwater species of Menidia indicate a generic tendency to spawn during mid-morning. This pattern coupled with high tides that cover suitable spawning substrates during mid-morning only at fortnightly intervals could account for the semilunar spawning cycle in marine populations of Menidia. Although general characteristics of the reproductive ecology of M. menidia in Massachusetts were similar to a thoroughly studied population in South Carolina, several differences were evident. The breeding season was shorter in Massachusetts (late; April–June), and occurred over a much lower range of temperatures (9–21°C). Intensity and frequency of spawning was correlated with the height of high tide. Eggs were deposited only on mats of intertidal, filamentous algae rather than on roots or stems of Spartina alterniflora or other intertidal vegetation. Promiscuous spawning occurred in small, highly male-dominated groups of fish, primarily after the tide had begun to recede, and often at the water's edge. No predation on spawning adults was observed but the mummichog, Fundulus heteroclitus, fed daily on developing embryos during high tide. Contribution No. 81, Massachusetts Cooperative Fisheries Research Unit, Contribution No. 349, Marine Sciences Research Center, State University of New York at Stony Brook.     

Aspects of the spawning of western Atlantic butterflyfishes (Pisces: Chaetodontidae)

Synopsis The status of knowledge of spawning among the five shallow waterChaetodon species in the western Atlantic is reviewed. Spawning has been observed for three species in Puerto Rico, St. Croix and the Bahamas, with possible courtship in a fourth.Chaetodon aculeatus spawned near the time of sunset over objects on the reef as single female/male pairs or as two females and one male, with pair spawning in rapid succession. Spawning occurred during much of the lunar month from February to April and it is uncertain whether any lunar periodicity to spawning exists. Male-male aggression was noted. Spawning sites (coral heads) were alternated daily and it is likely that females spawn only once every two days. A single female produced as many as 2090 eggs in a single spawning.Chaetodon capistratus spawned during much of the lunar month from February to April. It spawned about 5 min afterC. aculeatus, occasionally using the same sites, and alternated sites daily. A female produced as many as 3710 eggs in one spawning.Chaetodon striatus spawned from February to April but it is unknown if it has any lunar spawning cycle. No predation attempts by piscivores on spawning adults were seen. Predation byMelichthys niger on eggs ofC. striatus occurred. No egg predation was observed forC. aculeatus andC. capistratus. With an assumed four month reproductive season, alternate day spawning and observed egg production values,C. aculeatus andC. capistratus produce respectively about 100 000 and 200 000 eggs per large female per year. The reproductive strategy of smaller species may be to produce moderate numbers of eggs per day over a spawning season of at least a few months while larger species may produce more eggs per day for a shorter period.     

A new species of Dichelyne (Nematoda: Cucullanidae) parasitizing Acanthistius brasilianus (Pisces: Serranidae) from Argentinean waters

During a parasitological examination of 45 specimens of Acanthisthius brasilianus (Valenciennes, 1828) Jordan et Eigenmann, 1890, from waters off Mar del Plata, Argentina (38 degrees 08'S, 57 degrees 32'W), several specimens of cucullanid nematodes were collected from the intestines. A new species, Dichelyne (Cucullanellus) szidati n. sp., is described (prevalence 42.2%, mean intensity 2.7). The new species differs from its congeners inhabiting the southwestern Atlantic by the distribution pattern of caudal papillae, particularly the ninth pair, length of the body and spicules, and the position of the intestinal cecum (ventral), the excretory pore (posterior to esophagus), and the deirids (at the level of esophageal posterior end).     

Biochemical systematics of some serranids from Taiwan (Pisces, Serranidae)

An electrophoretic study of genetic variation at 17 loci in ten serranids belonging to three subfamilies (Anthiinae, Epinephelinae and Serraninae) was carried out to assess their systematic relationships. A relationship dendrogram was constructed from the fenetic identities calculated b Nei's method for all pairwise cornarisons. These fishes were divided into three major welldefined groups: Anthiinae, Epinepielinae and Serraninae. Although the relationships among them appear slightly different from that deduced from morphological features; e. g., Serraninae are distant from Anthiinae and Epinephelinae biochemically, but are closer to Antiinae than to Epinephelinae morphologically. However, a tendency for an increase of the genetic distance in higher categories is obvious (Table 5).