Thalassoma Lucasanum Research Articles

Aproximación a la dieta de Thalassoma lucasanum (familia Labridae) en el arrecife coralino de La Azufrada, isla Gorgona, Pacífico Oriental Tropical

El arcoíris de Cortés, Thalassoma lucasanum, es un pez arrecifal abundante en el Pacífico Oriental Tropical (POT). A diferencia de otras especies del género Thalassoma que son reconocidas por ser limpiadoras, en T. lucasanum este comportamiento es poco frecuente, ya que se alimenta principalmente de invertebrados mediante forrajeo. No obstante, la información sobre la ecología trófica de esta especie es limitada, especialmente en el POT. En este estudio se caracterizan los hábitos alimentarios de T. lucasanum en la isla Gorgona (POT) a partir del análisis de su contenido estomacal y se calcula su nicho trófico. Los moluscos fueron el principal recurso alimentario de T. lucasanum, siendo este el ítem de presa más importante y frecuente al ser encontrado en 100 % de los estómagos analizados (n = 5). En términos de biomasa, los crustáceos presentaron la mayor contribución a la dieta, con lo cual se posicionaron como el segundo ítem alimentario más importante. Otras presas incluyeron poliquetos, partes de peces y material calcáreo. Este estudio contribuye al conocimiento de la dinámica trófica de los ecosistemas arrecifales del POT.

Temporal and Spatial Structure of the Reef Fish Community of the West Coast of La Paz Bay, México

Ecological studies were performed to evaluate the temporal and spatial variation of reef fish communities of eight localities of the west coast of La Paz Bay, from March 2002 to April 2003. Visual census with 48 transects of 100×5 m (500 m2) were performed. Two climate seasons were detected: cold and warm. A total of 26,608 organisms from 112 species and 76 genera were observed. Relative abundance index was used to determine the most important species, which were: Abudefduf troschelii, Thalassoma lucasanum, Stegastes rectifraenum, Mulloidichthys dentatus, Chromis atrilobata, Lutjanus argentiventris, and Scarus ghobban. Diversity determined in February showed the lowest value (3.12 bits/ind.) and October showed the highest value (4.13 bits/ind.). According to the biological value index (BVI), and considering the climate seasons, species that obtained a higher score during the cold months were: Abudefduf troschelii, Mulloidichthys dentatus, Scarus ghobban, Stegastes rectifraenum, Thalassoma lucasanum, and during the warm months the same species were observed but in different order and abundance: Abudefduf troschelii, Scarus ghobban, Stegastes rectifraenum, Thalassoma lucasanum and Mulloidichthys dentatus. A higher number of species and higher abundance of fish were observed in the localities of the eastern part of the island. The principal component analysis (PCA) shows habitat characteristics and ecological features, where a strong correlation between these and rugosity was observed.

Reef Community Changes Associated with the 2009–2010 El Niño in the Southern Mexican Pacific

Abstract: We surveyed coral reefs communities before (September 2007–March 2009) and during (September 2009) the 2009–2010 El Nino event on the coast of Oaxaca, southern Mexican Pacific to evaluate community changes associated with the warming event. From May 2009 to December 2010, we recorded positive deviations from the historical in situ sea surface temperature values. There were differences among the coral species Pocillopora damicornis, Pavona gigantea, and Porites panamensis with significant reductions in chlorophyll a and Symbiodinium density during El Nino, resulting in bleaching (>13%) and increase in algal coverage (mainly geniculate coralline algae). Concurrently, echinoderm and fish assemblages also experienced significant modifications; abundances of the sea urchins Eucidaris thouarsii and Centrostephanus coronatus increased during the warming event, whereas Diadema mexicanum declined; meanwhile, fish species such as Thalassoma lucasanum declined in favor of Stegastes acapulcoensis and Haemul...

Estructura de las comunidades de peces de las bahías Maguey y Cacaluta, Huatulco, Oaxaca

This study describes the composition and structure of the fish communities in Maguey and Cacaluta Bays. Ichthyofauna was characterized using transect visual census in February, April and July of 2004. A census was taken in both localities of 2 874 individuals belonging to 42 species. Pomacentridae and Labridae were the families that were most represented. Thalassoma lucasanum, Chromis atrilobata, Stegastes acapulcoensis and Microspathodon dorsalis were the dominant species. Composition, species richness, abundance, diversity and dominance presented notable spatial differentiation, making it possible to distinguish 3 ictic components in each locality: sandy, rocky and coralline. The coralline component registered the greatest species richness, abundance and diversity due to the high structural complexity of its environment. The sandy component presented the greatest dominance. The dry seasons presented the greatest abundance, primarily determined by the increase in the abundance of C. atrilobata and T. lucasanum. The greatest species richness and diversity was present during rainy seasons, likely due to high temperatures and high production associated with regional coastal processes.

Estructura temporal y espacial de la comunidad de peces arrecifales de la Isla San José, Golfo de California, México

The Gulf of California is one of the most fish diverse areas of the Tropical Eastern Pacific Ocean. In spite of its economic value, few works have considered fish community studies for optimum management. With the aim to determine the seasonal and spatial variation of fish communities in eight locations around the San José Island, some ecological research was conducted from March 2001 to February 2002. For this, visual censuses were used in 48 transects of 100x5m (500m2); specific analysis such as diversity values, the relative abundance and the biological value indexes were undertaken, and a principal component analysis applied. Our results clearly showed two climatic seasons of cold and warm waters. A total number of 26 608 organisms of 112 species and 76 genera of fishes were identified. We used the relative abundance index to determine the most important species, which were: Abudefduf troschelii, Thalassoma lucasanum, Stegastes rectifraenum, Mulloidichthys dentatus, Chromis atrilobata, Lutjanus argentiventris and Scarus ghobban. February was the month with the lowest diversity with a value of 3.12bits/ind. and October was the most diverse (4.13bits/ind.). According to the biological value index (BVI) and considering the climatic seasons, the fish species with the highest score during cold months were: A. troschelii, M. dentatus, S. ghobban, S. rectifraenum and T lucasanum. Besides, for warmer months, the same fish species were observed but in different order and abundance: A. troschelii, S. ghobban, S. rectifraenum, T lucasanum and M. dentatus. Using the biological value index, 13 species were those which had a higher overall score. The locations by the Eastern side of the island had a greater number of species and abundance of fish. The principal component analysis (PCA) applied using the seasonal data, species richness, diversity, equity, number of species and total abundance during the warmer months also a PCA within spatial data, showed that location in Punta Colorada had a high correlation with the number of species, diversity and total abundance.

Changes in the taxonomic diversity of the reef fish community of San José Island, Gulf of California, Mexico

Although San Jose Island is considered one of the most important islands in the lower Gulf of California due to its commercial fishing activities, few studies have evaluated their fish taxonomic diversity. The aim of this study was to determine the variation in the taxonomic diversity of the conspicuous fish community in eight locations around San Jose Island from March 2001 to February 2002. We assessed the changes in the diversity of rocky reef fish based on the taxonomic distances between species, using Fisher’s alpha diversity index, average taxonomic distinctiveness (AvTD Δ+), and taxonomic distinctiveness (Δ*). Visual censuses were conducted in 48 transects consisting of 100 × 5 m quadrants (500 m2 sampling area) at an average depth of 5 m, from 09:00 to 16:00. A total of 26,608 fishes belonging to 112 species and 76 genera were found. The index of relative abundance was used to determine the most important species, which were in order of abundance: Abudefduf troschelii, Thalassoma lucasanum, Stegastes rectifraenum, Mulloidichthys dentatus, Chromis atrilobata, Lutjanus argentiventris, and Scarus ghobban. According to Fisher’s alpha diversity index, the highest diversity of species was found in July and the lowest in February. The indices of Δ+ and Δ* indicated significant temporal and spatial differences.

Ensamblajes de peces arrecifales y su relación con el hábitat bentónico de la Isla Isabel, Nayarit, México

This study describes the reef fish assemblages of Isabel Island and their relation with the benthos heterogeneity. A total of 39 visual transects from 19 different localities were performed in the zones North, South, East, and West around the island during December 2002, October 2004, and April 2005. The species composition and their abundance were registered in each transect. Video-transects were also performed to estimate the cover of benthic morpho-functional groups. A total of 9,956 specimens of fishes belonging to 118 species, 85 genera, and 51 families were registered. The 58.3% of the species have biogeographic affinity to the Panamic province. Six endemic species of the Mexican Pacific were registered, including two species endemic to the Gulf of California. According to the biological value index seven species were dominant in the island: Thalassoma lucasanum, Prionurus punctatus, Stegastes flavilatus, Halichoeres dispilus, Acanthurus xanthopterus, Abudefduf troschelii, and Johnrandallia nigrirostris. The indexes of diversity and evenness were not significantly different between the four zones of the island. However, there was a relation between the zones with higher biodiversity (South and East) and some components of the benthic habitat. The principal component analysis found that the cover of corals and rocks are highly related with the dominant species of the island, while the zones with highest proportion of sand, sponges, and gorgonians have less influence on fish diversity.

Long-term comparison of the fish community in a Costa Rican rocky shore marine reserve

Despite their role in supporting diverse marine fish communities, tropical rocky shores and reefs have attracted less research and fewer targeted conservation efforts compared to coral reefs. We studied fish community composition in Playa Blanca Marine Reserve (9 degrees 40' N - 84 degrees 40' W), a rocky shore site on the central Pacific coast of Costa Rica. We conducted visual surveys of fishes along six strip transects soon after the area was designated a marine reserve in 1995, then again in 2006 following an eleven-year period of complete protection. We recorded a total of 31 406 sightings of 72 species from 30 families. Pomacentrids (42.5%), labrids (16.6%) and haemulids (14.8%) dominated the community, accounting for > 70% of total fish abundance. In comparison to other sites in the region, the fish community was more similar to one reported from Bahia Honda, Panama (7 degrees 50' N - 81 degrees 35 W) than from the geographically more proximate Culebra Bay, Costa Rica (10 degrees 45' N - 85 degrees 43 W). Sixty-one species from 26 families were recorded in 1995; sixty-nine species from 28 families in 2006. Our results suggest that the Playa Blanca Marine Reserve is fulfilling its conservation role. Average fish abundance, species richness and Shannon's index of community diversity were greater in 2006 than 1995, and fish community composition varied significantly within each transect among years. Much of the change in community composition among years resulted from spatial and temporal variation in the abundance of a few dominant species, including Abudefduf troschelli, Thalassoma lucasanum, Chromis atrilobata, and Stegastes flavilatus/acapulcoensis. Of the 48 species/species groups recorded in both years, 37 (77%) were more abundant in 2006 than 1995, and several species recorded as uncommon or rare in 1995 were more frequent and abundant in 2006. Fish community composition and the abundance of some species changed in the reserve over time, but further study is needed to determine the role of small-scale marine reserves in the conservation of tropical marine biodiversity.

Effects of the aquarium fish industry in Costa Rica on populations of the Cortez rainbow wrasse Thalassoma lucasanum

Costa Rica hosts an active industry for the collection of marine ornamental reef fish that are supplied to the international aquarium fish trade. Little is known about the effects that collection activities may be having upon target species in Costa Rica, although research elsewhere gives reason for concern. Thalassoma lucasanum (Cortez rainbow wrasse) is an important species in this fishery. Costa Rican collectors prize the vibrantly colored terminal phase T. lucasanum individuals, but also collect the less dramatic initial phase T. lucasanum. We measured the density of T. lucasanum and the length of terminal phase individuals on highly collected reefs close to a fishing village and on nearby less-collected reefs located within the Guanacaste Conservation Area. Our findings show that densities of T. lucasanum were significantly lower and that terminal phase individuals were significantly smaller on the reefs near the fishing village where collection pressure was high. These findings indicate that even moderate amounts of relatively non-destructive aquarium fish extraction can negatively affect targeted populations. We present some suggestions for the reform of the aquarium reef fish industry in Costa Rica, which we believe would improve the long-term sustainability of this fishery.

Community structure of fishes in Cabo Pulmo Reef, Gulf of California

AbstractIn order to analyse the structure of the fish community in Cabo Pulmo Reef., 36 cylindrical stationary censuses (5 m radius, 15 min of observation time) were conducted in October 2003 (warm season) and February 2004 (cold season). To explore the relationship with depth and associated variables, we considered a shallow stratum (<5 m) and a deep stratum (>5.5 m; depth range was between 2 and 15 m). Species richness, number of individuals, and the indices of diversity (Shannon), evenness (Pielou) and taxonomic distinctness were computed for each census. A total of 8725 fish were recorded (3829 in the warm season and 4896 in the cold season), belonging to 62 species, included in 23 families. Thalassoma lucasanum and Chromis atrilobata were the dominant species (62.5% of total abundance, and occurrence of 97% and 72%, respectively). Conversely, 50 species had low relative abundance, <1% of total abundance, and a frequency of occurrence <50% of the census. None of the ecological descriptors were significantly different between seasons (P > 0.5), but richness, abundance and taxonomic differentiation were higher in the deeper zone. The analysis of similarity and ordination analysis did not show consistent clusters by season or depth, but suggest similarity among census of deeper zones. Most species preference for physical factors associated with deeper zones maybe the reason for the pattern observed in this study.

Temporal and spatial variations in the structure of the rocky reef fish community of the southwest Gulf of California, Mexico

Many rocky reefs exist in the Gulf of California; however, there are few studies on the fish communities that inhabit them. In the present work, these communities are evaluated through visual censuses at four sites of the southwestem coast of the gulf. The specifíc richness, frequency, evenness and diversity were analyzed at each site. Seasonal changes and differences among the sites studied were also analyzed. A total of 76 species was registered. Five species were the most abundant in most of the zones and during the greater part of the study: Stegastes spp., Thalassoma lucasanum, Abudefduf troschelii, Chromis atrilobata and Haemulon maculicauda. Only the first three species were present in all censuses made. Differences were found in the structure of the communities between different seasons and between study sites; however, the diversity values had no significant differences. The zone with the greatest number of species was Cueva de León. A positive relationship was found between specific richness and temperature.

Regional differences in duration of the planktonic larval stage of reef fishes in the eastern Pacific Ocean

Regional variation in the duration of the planktonic larval phase of three species of reef fishes, Thalassoma lucasanum (Labridae), Stegastes flavilatus, and Microspathodon dorsalis (Pomacentridae) was investigated between 1982 and 1991 at several sites in the tropical eastern Pacific over a distance of 3500 km, encompassing virtually their entire range of distribution. Durations of the larval phase, determined from counts of daily otolith increments, were significantly different (1.3 to 1.6 x) between sites. Populations of all three species had a consistently shorter larval life at the most northern site, Cabo San Lucas (Mexico) compared to Panama and the offshore islands of Galapagos and Cocos. Analyses of otolith increment width over the precompetent period revealed that this disparity in larval duration primarily reflected differences in larval growth rates: faster growing fish spent less time in the plankton. In T. lucasanum, some of the variation in larval duration between Panama and offshore sites (Galapagos Islands and Cocos Island) may be accounted for by a higher frequency of individuals delaying metamorphosis at the offshore sites. These data indicate that conditions in the planktonic environment are not homogeneous throughout the tropical eastern Pacific and may have a profound effect on aspects of the larval ecology of reef fishes in this region.

The implications of divergence in spatial nesting patterns in the geminate Caribbean and Pacific sergeant major damselfishes

Male Caribbean Abudefduf saxatilis, and Pacific, A. troschelii, sergeant majors nest in colonies, but nest densities in the Pacific are much greater than in the Caribbean. The relatively dense within-colony aggregations in the Pacific have apparently been favoured by the screening effects of defence by peripheral males against foraging groups of the wrasse, Thalassoma lucasanum, resulting in lower rates of predation on embryos guarded by males with centrally placed nests. Males with centrally placed nests were also more likely to spawn successfully than were those with peripheral nests, suggesting that aggregated nesting has been further reinforced by female preferences for males with nests in which risk of predation on embryos is lowest. In the Caribbean, where similar predation on embryos was absent, relatively slight within-colony spatial aggregation of nesting was observed. This tendency might be maintained by female preferences for males with close nearest-neighbour distances because males that failed to spawn had longer nearest-neighbour distances than those that did spawn, but the difference was only marginally significant. Alternatively, because the Caribbean and Pacific species are thought to have been derived from a single population following the uplift of the isthmus of Panama, it is possible that spatial aggregation represents a residual tendency, originally favoured by selection under ancestral conditions.

Acquisition of a defended resource: a benefit of group foraging for the neotropical wrasse, Thalassoma lucasanum

The neotropical Pacific wrasse, Thalassoma lucasanum, forms groups of 30 to 300 individuals that overwhelm the defense of embryos by the Pacific sergeant major, Abudefduf troschelii, and thereby gain access to a food resource from which solitary individuals are effectively excluded by paternal defense. The duration of feeding by the wrasse groups and the fraction of embryos eaten in a nest are positively correlated with group size. The benefit of group foraging is probably derived from a reduction in the frequency with which group members experience attack by defending sergeant majors, as reflected in the positive correlation of group size with feeding duration. Large foraging groups only form when sergeant major embryos are present in nests, indicating that this is a primary benefit of participation in these groups for this wrasse. In contrast, in the Caribbean large foraging groups of the congeneric bluehead wrasse, T. bifasciatum, fail to form despite the presence of defended embryos of the Caribbean sergeant major, A. saxatilis. This might be due to the relatively low population densities of the Caribbean wrasse in comparison to those of the Pacific wrasse or to the relatively low densities of Caribbean sergeant major nests containing embryos at any time.

Mating Systems, Sex Change and Sexual Demography in the Rainbow Wrasse, Thalassoma lucasanum

Previous work indicates that sex change becomes less advantageous and less common in fish species which live at relatively high population densities. This study extends these observations to the abundant rainbow wrasse (Thalassoma lucasanum) of the eastern tropical Pacific. In this species, large territorial males in terminal phase coloration are uncommon, and the overwhelming majority of spawnings occur in groups of smaller initial phase males. For T. lucasanum, sex change itself is a relatively rare event; fewer than 30% of the terminal phase individuals are derived from females. The initial phase population consists of nearly 50% primary males, their theoretical maximum abundance. Laboratory experiments indicate that sex and color change is socially mediated: the largest individual changed color (and sex if she was a female) in ten groups initiated without a terminal phase male, while no transformations occurred in 15 control groups. The retention of sex-changing ability should carry little or no cost even in densely distributed populations, and can be of great advantage in any small groups that might exist. In addition to ensuring proper timing of transformation in small groups, social mediation of sex change may be of value in preventing sex change from occurring at all in situations where the costs of transformation are too great.

Fish Predation: A Preliminary Study of its Role in the Zoogeography and Evolution of Shallow Water Idoteid Isopods (Crustacea: Isopoda: Idoteidae)

Behavioural, morphological and distributional patterns of idoteid isopods (family Idoteidae) from the northeast Pacific are analysed with respect to the hypothesis of increasing predation pressure from fishes in the lower latitudes. Minimum reproductive size and maximum body length of idoteids both decrease with decreasing latitudes; body ornamentation increases with decreasing latitudes. Members of the tropical and subtropical genera Parasymmerus, Eusymmerus, Colidotea and Erichsonella are smaller and more ornamented than species of the temperate genus Idotea. The subtropical isopod Colidotea findleyi is a 'swimmer', whereas the larger, more conspicuous, temperate species Idotea urotoma shows no preference between 'swimming' and 'nonswimming' behaviour. In laboratory predation experiments, the tropical wrasse Thalassoma lucasanum selected larger isopod prey items, as well as preferring Idotea urotoma over Colidotea findleyi of equal length. The geological evolution of the region is discussed in regards to vicariant events, shifting faunal waves, and modern zoogeographic patterns of idoteid isopods. Data obtained in this study support the hypothesis that fish predation may play a major role in controlling the southern range limits of temperate rocky-shore isopods, and that this same pressure may have affected the evolution of idoteid isopod body size and morphology in the northeast Pacific.

Los peces del arrecife de Cabo Pulmo, Golfo de California, México: Lista sistemática y aspectos de abundancia y biogeografía

The Cabo Pulmo reef is the most important coral formation of the Gulf of California; however, its ichthyological fauna has been poorly studied. To produce a systematic list with data on relative abundance and frequency, and biogeographical affinities, we relied on visual census, field observations, analysis of commercial and sport fisheries (from 1986 to 1998), and the literature. A total of 236 species have been recorded at Cabo Pulmo (155 genera and 60 families). This number doubles previous compilations and represents 65.1% of all reef fishes known from the Gulf of California, and about 35% of its entire shallow-water fishes. Of the total species number, 68.3% are from the Panamic Province, 11.0% Indo Pacific colonizers and the same percentage gulf endemics, 7.6% are circumtropical, 1.7% Atlantic and 0.5% cosmopolitan; none are endemic to the reef. The most abundant taxa are the labrids Thalassoma lucasanum, T. grammaticum and the pomacentrid Chromis atrilobata. Only eleven species (4.7% of total) appeared in 75% to 100% of census, and 36 (15.3% of total) had high levels of both abundance and frequency, evidencing that the community is dominated by few taxa. Local species richness exceeds the number reported for most rocky or coral reefs of the Pacific coast of México, and indicates that Cabo Pulmo is a key area in the gulf and the entire Mexican Pacific, from the ichthyological point of view.

Possible Advantages to the Blenny Runula azalea in Aggregating with the Wrasse Thalassoma lucasanum in the Tropical Eastern Pacific

Possible Advantages to the Blenny Runula azalea in Aggregating with the Wrasse Thalassoma lucasanum in the Tropical Eastern Pacific

Diurnal-Nocturnal Activity of Some Inshore Fishes in the Gulf of California

the southern Gulf of California. Certain patterns of behavior within and between species were consistently observed, and permit a number of tentative generalizations regarding feeding habits, schooling, and other activity in relation to time of day. Species with predominently diurnal foraging habits include: Mycteroperca rosacea (Streets), Epinephelus labriformis (Jenyns), Chromis atrilobata (Gill), Eupomacentrus rectifraenum (Gill), Abudefduf troschelii (Gill), Bodianus diplotaenia (Gill), Thalassoma lucasanum (Gill), Scarus californiensis (Pellegrin), Heniochus nigrirostris (Gill), Prionurus punctatus Gill, Runula azalea Jordan and Bollman, Balistes verres Gilbert and Starks, and Balistes polylepis Steindachner. Species obtaining most of their food at night include: Holocentrus suborbitalis (Gill), Myripristis occidentalis Gill, Rypticus bicolor (Valenciennes), Lutjanus argentiventris (Peters), Apogon retrosella (Gill), Microlepidotus inornatus Gill, Anisotremus interruptus Gill, Haemulon sexfasciatum Gill, Selar crumenophthalmus (Bloch), and Pareques viola (Gilbert). A number of other species are introduced as their activity relates to the discussion. The nocturnal species are predators, while the herbivorous and omnivorous fishes show predominantly diurnal feeding habits. Those species schooling in dense, relatively inactive schools inshore during the day are nocturnal feeders and the school functions in defense against diurnal predators. Members of these schools disperse to feed at night, often after moving a considerable distance offshore.