Lutjanus Apodus Research Articles

Behavior and space utilization of two common fishes within Caribbean mangroves: implications for the protective function of mangrove habitats

Behaviors, activity budgets, and spatial locations of reef-associated schoolmaster snapper ( Lutjanus apodus) and non-reef-associated checkered puffer ( Sphoeroides testudineus) were cataloged in mangrove forests in Caribbean Honduras to see how and where they spent their time and whether this changed as they grew. For schoolmasters, swimming was the most common behavior, while checkered puffers spent the majority of their time resting. Both remained completely within (as opposed to outside) the mangrove roots and in the lower half of the water column most of the time. However, as the size of the fish increased there was a clear decrease in the time spent both within the root system and closer to the substrate; the larger fish spent more time higher up in the water column and outside the root system. This was observed in both the schoolmaster and the puffer; the schoolmaster subsequently moves to reefs while the puffer does not. Coupled with limited feeding, the results suggest a primarily protective function for mangroves.

Physiological tolerance to hyperthermia and hypoxia and effects on species richness and distribution of rockpool fishes of Loggerhead Key, Dry Tortugas National Park

Rockpools on Loggerhead Key in the Dry Tortugas National Park experience cyclic tidal changes in water quality and physical dimension resulting in ichthyofaunal assemblages that differ markedly from the adjacent coral reef. Within the beach rock formations and areas transitioning to the nearby reef, we observed 45 fish species; however, only four species – schoolmaster, Lutjanus apodus, French grunt, Haemulon flavolineatum, cocoa damsel, Pomacentrus variabilis, and frillfin goby, Bathygobius soporator – were found in all rockpools. All fishes were transient juveniles except for frillfin goby, which was a pool resident. High temperature tolerance, (Critical Thermal Maxima), and low oxygen tolerance, (Critical Oxygen Minima) for schoolmaster, French grunt, cocoa damsel, and frillfin goby were 40.9, 36.2, 37.6, 40.9 °C and 0.56, 0.77, 0.50, and 0.27 mg/L, respectively. All four species demonstrated thermal and hypoxia tolerance values similar to those published for species traditionally noted as abiotic specialists. Although fish distribution patterns in rockpools were likely influenced by structural complexity and spatial limitations, the relationship between pool morphology and species richness was weak, suggesting that physiological tolerance to high temperature and low oxygen among reef fishes may be more influential in determining which species inhabit the rockpools. Harsh thermal and oxic conditions that cannot be exploited by less tolerant species may be beneficial for some Loggerhead Key reef fishes in providing refuge from predators, foraging grounds, or potential nursery areas.

Testing assumptions of mark–recapture theory in the coral reef fish Lutjanus apodus

This study tested assumptions of the Cormack–Jolly–Seber capture–mark–recapture (CMR) model in a population of the tropical snapper Lutjanus apodus in the central Bahamas using a combination of laboratory and field studies. The suitability of three different tag types [passive integrated transponder (PIT) tag, T‐anchor tag and fluorescent dye jet‐injected into the fins] was assessed. PIT tags were retained well, whereas T‐anchor tags and jet‐injected dye were not. PIT tags had no detectable effect on the rates of growth or survival of individuals. The capture method (fish trapping) was found to provide a representative sample of the population; however, a positive trap response was identified and therefore the assumption of equal capture probability was violated. This study illustrates an approach that can be used to test some of the critical assumptions of the CMR theory and it demonstrates that CMR methods can provide unbiased estimates of growth and mortality of L. apodus provided that trap response is explicitly modelled when estimating survival probability.

Influence of habitat configuration on connectivity between fish assemblages of Caribbean seagrass beds, mangroves and coral reefs

The importance of seagrass beds and mangroves as juvenile habitats for coral reef fishes is still debatable. We hypothesised that the configuration of these habitats in the marine landscape in relation to the coral reef would influence accessibility from the reef (both for fishes that use these habitats for shelter or feeding, and their predators). In combination with differences in habitat com- plexity (related to habitat type) this could influence the utilisation of these habitats by juvenile reef fishes, and connectivity with the coral reef. Using underwater visual census, we studied the use by juvenile reef fishes of various seagrass and mangrove habitats situated differently in relation to the coral reef, on the Caribbean island of Aruba. Additionally, we studied fish assemblages on various coral reefs differing in proximity to seagrass Thalassia testudinum and mangrove Rhizophora mangle habitats at the scale of the whole island. In the seagrass and mangrove habitats, habitat configuration in relation to the reef was related to the composition of the fish assemblage, species richness, fish density and fish size. This was consistent with our expectations related to accessibility of these habi- tats from the reef, and habitat complexity. Most fish species that use seagrasses and mangroves as juvenile habitats were absent from or showed reduced densities on coral reefs located far (>9 km) from seagrass-mangrove habitats. At a smaller spatial scale, this effect was less clear. For some spe- cies, this lack of an effect at smaller spatial scales may be explained by local recruitment to the reef, whereas for other species (i.e. Haemulon sciurus, Lutjanus apodus, L. mahogoni and Scarus guaca- maia) migration along the coast offers a more likely explanation. We suggest that the value of sea- grass and mangrove habitats as a juvenile habitat should not be generalised a priori, since habitat configuration may interact with the degree of connectivity between seagrasses, mangroves and coral reefs.

Habitat selection during settlement of three Caribbean coral reef fishes: Indications for directed settlement to seagrass beds and mangroves

We studied the settlement patterns of three Caribbean coral reef fishes in three different habitat types: mangroves, seagrass beds, and coral reefs. The settlement patterns of the three species were not random and could best be explained by active habitat selection during settlement. Acanthurus bahianus preferentially settled on the shallow reef flat and in adjacent seagrass beds, Lutjanus apodus settled exclusively into mangroves, and Ocyurus chrysurus, settled into both mangroves and seagrass beds. The settlement patterns of these three species reflect their habitat utilization during later juvenile stages. This study, therefore, suggests that the higher juvenile densities in mangroves and seagrass beds are determined by habitat selection during settlement rather than by post‐settlement processes. This habitat selection during settlement is in accordance with the assumed importance of mangroves and seagrass beds as juvenile habitats of coral reef fishes and underlines the pressing need for their conservation.

Anaesthetic effects of clove oil on seven species of tropical reef teleosts

The anaesthetic potential of the clove oil was tested on the following species of tropical reef fishes: Abudefduf saxatilis, Stegastes variabilis, Pareques acuminatus, Acanthurus chirurgus, Sparisoma axillare, Lutjanus apodus and Bathygobius soporator. Induction and recovery times from anaesthesia were compared using various concentrations (20, 30, 40, 50 and 60 mg l−1). Induction and recovery times were not affected by variations in fish total length. When exposed to any of the five tested concentrations of clove oil, specimens achieved a deep state of anaesthesia, with induction and recovery times of <180 and <300 s, respectively. Nevertheless, to maximize safety and reduce fish mortality and stress, the lowest concentration (20 mg l−1) is recommended during field sampling.

ET743: Chemical analysis of the sea squirt Ecteinascidia turbinata ecosystem

The sea squirt Ecteinascidia turbinata produces the powerful drug ET743. In this study Inductively Coupled Plasma–Atomic Emission Spectroscopy (ICP–AES) and Matrix Assisted Laser Desorption Ionization–Mass Spectrometry (MALDI–MS) are systematically used to measure elemental and molecular species in a Florida Keys mangrove ecosystem that contains the sea squirt. ICP–AES is used to measure the concentration of 27 elements down to the parts per billion level in 16 organisms and 3 sediment samples that reside in the mangrove ecosystem including turtle grass, blue crabs, fire sponge, and lettuce slugs. MALDI–MS is used to search for ET743 in these same organisms and sediment samples. A mass spectral feature corresponding to ET743 is identified in the extract of the sea squirt, red mangrove root (Rhizophera mangle), the schoolmaster snapper (Lutjanus griseus), and a sediment sample taken from the ecosystem. We use MALDI–MS to study the impact that various environmental conditions, such as UV light, I2, cation binding (Fe+3, Zn+2, Pb+2, Cu+2), metal oxide nanoparticles (FeO, CuO, TiO2, ZnO, Al2O3), a common mineral (CaCO3), and extremes in acidity (0.1 M HCl, 0.1 M NaOH) have on the ET743 structure. The data provide potential structures (degradation products, metal–ligand complexes, etc.) that might be present in organism or sedimentary extracts that are similar to ET743. We are studying the marine geochemistry of this ecosystem so a broth can be developed and tested for producing this marine natural product.

Spatial variation in otolith chemistry of Lutjanus apodus at Turneffe Atoll, Belize

Lutjanus apodus (Schoolmaster) were collected from several mangroves and coral reefs at Turneffe Atoll, Belize, in order to investigate whether elemental concentrations from the otolith edge could be used as a means to identify the habitat (mangrove or coral reef) and site (9 mangrove sites and 6 reef sites) from which they were collected. Results of a two factor nested MANOVA (sites nested within habitat) indicated significant differences in elemental concentrations between habitats (i.e., mangrove versus reef) as well as among sites. When separate Linear Discriminant Function Analyses (LDFA) were used to assess whether the spatial variability in otolith chemistry was sufficient to differentiate individuals to their respective habitats or sites, the results indicated that fish were classified (jackknife procedure) with a moderate to poor degree of accuracy (i.e., on average, 67% and 40% of the individuals were correctly classified to the habitat and site from which they were collected, respectively). Using a partial Mantel test we did not find a significant correlation between the differences in otolith elemental concentrations between sites and the distance between sites, while controlling the effect of habitat type (mangrove or reef). This suggests that for mangrove and reef sites at Turneffe Atoll, Belize, the overlap in terms of L. apodus otolith elemental concentrations is too high for investigations of fish movement. Finally, by comparing previously published Haemulon flavolineatum otolith chemistry to that of L. apodus we assessed whether these species showed similar habitat and/or site specific patterns in their otolith chemistry. Although both species were collected from the same sites our results indicated little similarity in their elemental concentrations, thus suggesting that habitat and site elemental signatures are species specific.

Variation in fish density, assemblage composition and relative rates of predation among mangrove, seagrass and coral reef habitats

We tested the hypothesis for several Caribbean reef fish species that there is no difference in nursery function among mangrove, seagrass and shallow reef habitat as measured by: (a) patterns of juvenile and adult density, (b) assemblage composition, and (c) relative predation rates. Results indicated that although some mangrove and seagrass sites showed characteristics of nursery habitats, this pattern was weak. While almost half of our mangrove and seagrass sites appeared to hold higher proportions of juvenile fish (all species pooled) than did reef sites, this pattern was significant in only two cases. In addition, only four of the six most abundant and commercially important species (Haemulon flavolineatum, Haemulon sciurus, Lutjanus apodus, Lutjanus mahogoni, Scarus iserti, and Sparisoma aurofrenatum) showed patterns of higher proportions of juvenile fish in mangrove and/or seagrass habitat(s) relative to coral reefs, and were limited to four of nine sites. Faunal similarity between reef and either mangrove or seagrass habitats was low, suggesting little, if any exchange between them. Finally, although relative risk of predation was lower in mangrove/seagrass than in reef habitats, variance in rates was substantial suggesting that not all mangrove/seagrass habitats function equivalently. Specifically, relative risk varied between morning and afternoon, and between sites of similar habitat, yet varied little, in some cases, between habitats (mangrove/seagrass vs. coral reefs). Consequently, our results caution against generalizations that all mangrove and seagrass habitats have nursery function.

The relationship of reef fish densities to the proximity of mangrove and seagrass nurseries

Visual census surveys were used to study the distribution of coral reef fishes that are associated with seagrass beds and mangroves in their juvenile phase, on various coral reef sites along the coast of the Caribbean island of Curaçao (Netherlands Antilles). The hypothesis tested was that various reef fish species occur in higher densities on coral reefs adjacent to nursery habitats than on reefs located at some distance to these habitats. Of 17 coral reef fish species that are known to use bays with seagrass beds and mangroves as nurseries (nursery species), 15 were observed in quadrats on the reef. Four nursery species, Haemulon sciurus, Lutjanus apodus, Ocyurus chrysurus and Scarus coeruleus occurred in significantly higher densities on coral reefs adjacent to bays with seagrass beds and mangroves. Lutjanus analis, Lutjanus mahogoni and Sphyraena barracuda also had their highest densities on reefs adjacent to these bays, although differences between the distinguished reef categories were not always significant. It is suggested that these seven species are highly dependent on the presence of bays with seagrass beds and mangroves as nurseries on an island scale. Eight other species that are known to use seagrass beds and mangroves as nurseries did not have their highest densities on reefs adjacent to bays with seagrass beds and mangroves. For six of these species, juveniles were also observed on the reef. It is suggested that these species are able to use the reef as an alternative nursery and do not depend strictly on the presence of bays with seagrass beds and mangroves as nurseries.

Are mangroves a limiting resource for two coral reef fishes?

Nearshore marine habitats, such as seagrass beds and mangroves, are generally assumed to be key nurseries for many marine species. Few studies, however, have examined relationships between the characteristics of juvenile habitats and the size of adult populations, although such studies are essential for confirming and quantifying the nursery function of these habitats. In this paper I describe the results of surveys of adult populations of 2 coral reef fish species (the yellow-fin mojarra Gerres cinereus and the schoolmaster Lutjanus apodus) that are thought to be dependent on mangroves as nurseries in the Virgin Islands, Caribbean Sea, to determine if the size of nearby mangrove stands and their proximity to adult reef habitat are related to adult densities. The results indicate that these 2 factors do not affect adult fish densities on coral reef patches. However, evidence suggests that a relationship between the island-wide size of mangroves and adult fish densities and population sizes exists for at least 1 fish species at the island scale, indicating that juvenile habitat may limit adult fish numbers for some species at this scale.

Diet shifts of Caribbean grunts (Haemulidae) and snappers (Lutjanidae) and the relation with nursery-to-coral reef migrations

The spatial size distribution of grunts and snappers have previously indicated the separation of juveniles in nursery habitats from the adults on the coral reef. This implies life cycle migrations from nursery habitats (such as seagrass beds and mangroves) to the coral reef. If diet shifts are related to such migrations, then the diets of these fish must change before or around the fish size at which such migrations take place. A wide size range of juveniles of two grunt species ( Haemulon sciurus and Haemulon flavolineatum) and of two snapper species ( Lutjanus apodus and Ocyurus chrysurus) were caught in seagrass beds and mangroves, and their gut contents identified and quantified. Regression analysis between fish size and dietary importance of small crustaceans showed a negative relationship in all four species. Positive relations were found for H. sciurus, L. apodus and O. chrysurus between fish length and the dietary importance of decapods, and for L. apodusand O. chrysurus between fish length and prey fish importance. Critical changes in the fish diets with fish size were examined by application of a Canonical Correspondence Analysis (CCA). The CCA yielded three clusters of size-classes of fishes with similar diets, and application of a Mantel test showed that each of these clusters had significantly different diets, and that each cluster diet was significantly specialised. The size at which a fish species ‘switched’ from one cluster to another was compared with size-at-maturity data and with the typical size at which these species migrate from the nursery habitats to the coral reef. H. sciurus and H. flavolineatum may be prompted to migrate from the nursery habitats to coral reef habitats because of dietary changes, or because of the development of the gonads. For L. apodus and O. chrysurus, a dietary changeover forms a more likely explanation for nursery-to-reef migrations than does sexual maturation because these species reach maturity at sizes much larger than the maximum size of individuals found in nursery habitats. Although other factors may theoretically initiate or promote the migration patterns, the results of this study indicate that ontogenetic dietary changes may crucially influence the nursery-to-coral reef migrations of these reef fish species.

Environmental influences on patterns of larval replenishment of coral reef fishes

Spatial and temporal patterns of larval replenishment to the San Blas Archipelago were measured using 3 light traps in each of 3 habitats (exposed, lagoon and back-reef) over 18 lunar months from December 1996 to June 1998. Traps were sampled for 19 consecutive nights centred on the new moon in each month. The effects of environmental variables (wind speed and wind direction, tidal range, rainfall, solar radiation and water temperature) on catches were examined both in the days immediately prior to settlement and during the entire larval phase using 2 approaches. Firstly, time-series analyses were used to compare night-to-night patterns in light trap catches of 11 species (Astrapogon puncticulatus, Eucinostomus melanopterus, Lutjanus apodus, L. mahogani, Ophioblen- nius atlanticus, Stegastes dorsopunicans, S. partitus, S. planifrons Synodontidae spp., Thalassoma bifasciatum and an unidentified blenny) with environmental variables. Secondly, modified correla- tion analysis was used to examine the relationships between environmental variables, averaged over larval durations, and light trap catches of 6 of these species. Time-series analysis detected significant correlations between catches of 8 species and wind direction; however, correlations were often weak and variable in direction. Similarly, there were weak correlations between day-to-day catches of all but 3 species and water temperature. Modified correlation analysis also found that water temperature was correlated with catches of 4 species (Lutjanus mahogani, Stegastes dorsopunicans, S. partitus and S. planifrons). Catches of the remaining species, Ophioblennius atlanticus and Thalassoma bifas- ciatum, were not correlated with environmental variables in these analyses. Multiple-regression analysis could not detect any combined effects of environmental variables on patterns of light trap catches, although this analysis also identified weak correlations (R 2 = 0.08 to 0.29) between catches of Lutjanus mahogani, Ophioblennius atlanticus, Stegastes dorsopunicans, S. partitus, S. planifrons and Thalassoma bifasciatum and water temperature.

Dependence of Caribbean reef fishes on mangroves and seagrass beds as nursery habitats: a comparison of fish faunas between bays with and without mangroves/seagrass beds

Mangroves and seagrass beds are considered important nursery habitats for coral reef fish species in the Caribbean, but it is not known to what degree the fish depend on these habitats. The fish fauna of 11 different inland bays of the Caribbean island of Curacao were compared; the bays contain 4 different habitat types: seagrass beds in bays containing mangroves, seagrass beds in bays lacking mangroves, mud flats in bays containing mangroves and seagrass beds, and mud flats in bays completely lacking mangroves and seagrass beds. Principal component analysis showed a high similarity of fish fauna among bays belonging to each of the 4 habitat types, despite some dif- ferences in habitat variables and human influence between bays. Juveniles of nursery species—fish species using mangroves and seagrass beds as juvenile nurseries before taking up residence on reefs—showed highest abundance and species richness on the seagrass beds, and on the mud flats near mangroves and seagrass beds, but were almost absent from bays containing only mud flats. The high abundance and species richness on the mud flats near nursery habitats can be explained by fishes migrating from the adjacent mangroves/seagrass beds to the mud flats. Seagrass beds near to mangroves showed a higher richness of nursery species than did seagrass beds alone, suggesting an interaction with the mangroves resulting in an enhancement of species richness. Comparison of fish densities from the 4 different habitat types indicates that for the nursery species the degree of depen- dence on a combination of mangroves and seagrass beds as nurseries for juvenile fish is high for Ocyurus chrysurus and Scarus iserti, the dependence on seagrass beds is high for Haemulon parrai, H. sciurus, Lutjanus apodus, L. griseus, Sparisoma chrysopterum and Sphyraena barracuda, and the dependence on mud flats near mangroves/seagrass beds is high for L. analis. The dependence on mangroves and/or seagrass beds is low for Chaetodon capistratus, Gerres cinereus, H. flavolineatum and L. mahogoni, which can also use alternative nursery habitats.

Importance of Mangroves, Seagrass Beds and the Shallow Coral Reef as a Nursery for Important Coral Reef Fishes, Using a Visual Census Technique

The nursery function of various biotopes for coral reef fishes was investigated on Bonaire, Netherlands Antilles. Length and abundance of 16 commercially important reef fish species were determined by means of visual censuses during the day in six different biotopes: mangrove prop-roots (Rhizophora mangle) and seagrass beds (Thalassia testudinum) in Lac Bay, and four depth zones on the coral reef (0 to 3m, 3 to 5m, 10 to 15m and 15 to 20m). The mangroves, seagrass beds and shallow coral reef (0 to 3m) appeared to be the main nursery biotopes for the juveniles of the selected species. Mutual comparison between biotopes showed that the seagrass beds were the most important nursery biotope for juvenile Haemulon flavolineatum, H. sciurus, Ocyurus chrysurus, Acanthurus chirurgus and Sparisoma viride, the mangroves for juvenile Lutjanus apodus, L. griseus,Sphyraena barracuda and Chaetodon capistratus, and the shallow coral reef for juvenile H. chrysargyreum,L. mahogoni , A. bahianus and Abudefduf saxatilis. Juvenile Acanthurus coeruleus utilized all six biotopes, while juvenile H. carbonarium and Anisotremus surinamensis were not observed in any of the six biotopes. Although fishes showed a clear preference for a specific nursery biotope, most fish species utilized multiple nursery biotopes simultaneously. The almost complete absence of juveniles on the deeper reef zones indicates the high dependence of juveniles on the shallow water biotopes as a nursery. For most fish species an (partial) ontogenetic shift was observed at a particular life stage from their (shallow) nursery biotopes to the (deeper) coral reef. Cluster analyses showed that closely related species within the families Haemulidae, Lutjanidae and Acanthuridae, and the different size classes within species in most cases had a spatial separation in biotope utilization.

Risk factors of ciguatera in the French West Indies in Saint-Barthélémy, Saint-Martin and Anguilla

An epidemiological study on ciguatera fish poisoning in the French West Indies (St-Barthelemy, St-Martin and Anguilla) was conducted during the years 1985-1986. The investigation on intoxications shows a non seasonal significant prevalence. Though it was difficult to list the cases, the morbidity seems to vary between 7 and 30 per thousand. A study of fish toxicity was realised; 46 different species were tested (individually or by pools) by the mosquito bio-test. Observations of intoxications give the following results: High risk species: Caranx bartholomaei, C. lugubris, Seriola dumerili, Lutjanus apodus, L. jocu, Pristipomoides macrophtalmus, Gymnothorax funebris, G. moringa, Scomberomorus cavalla, S. regalis, Mycteroperca venenosa, M. tigris, Epinephelus morio, Sphyraena barracuda. Intermediate species: Caranx latus, C. ruber, Lachnolaimus maximus, Lutjanus analis, L. buccanella, L. griseus, Malacanthus plumieri, Scomberomorus maculatus. Low risk species: Balistes vetula, Alectis ciliaris, Haemulon album, Bodianus rufus, Halichoeres radiatus, Priacanthus arenatus, Alphestes afer. Many species are involved in the toxic food chain. New ones have been identified, but it is difficult to determine the toxic level range. A cartography is presented but no place is free of risk. A research of Gambierdiscus toxicus, the causal agent, on algal surface from dead corals was conducted around St-Barthelemy and St-Martin. The dinoflagellate is found in low or medium populations all around the islands with no difference between North and South. There is a maximal activity during the spring. A model of the epidemiology of the ciguatera in the area is proposed.

Ciguatera Toxins Adversely Affect Piscivorous Fishes

Abstract Four species of piscivorous fishes (coney Epinephelus fulvus; schoolmaster Lutjanus apodus; mahogany snapper L. mahogoni; and largemouth bass Micropterus salmoides) displayed distinct behavioral abnormalities after consumption of a ciguatoxic great barracuda Sphyraena barracuda. Samples of the great barracuda were fed to experimental fishes as ether-soluble extracts or as ground flesh. Largemouth bass were also fed freeze-dried cells of the dinoflagellate Gambierdiscus toxicus in a separate experiment and displayed a similar response, Signs of intoxication included skin color variations, inactivity, loss of equilibrium, erratic swimming, jerky feeding movements, and loss of orientation – and death, in the case of largemouth bass fed 1.0 g or more of great barracuda flesh or 7.1 mg·g–1 or more of great barracuda extract. These abnormalities usually were observed within 24 h after the feeding of toxic materials, and were apparent in some cases for as long as 76 d.

A Survey of the Blood Parasites of the Marine Fishes of Puerto Rico

Heart or arterial blood smears were made from 1,340 marine fishes of 126 species, collected from the coastal waters of Puerto Rico. The only blood parasites found were haemogregarines. Haemogregarina bigemina was present in 11 fishes belonging to the following eight genera: Hemiramphus brasiliensis (Linnaeus), Lutjanus apodus (Walbaum), Ocyurus chrysurus (Bloch), Caranx bartholomaei Cuvier, C. hippos (Linnaeus), Haemulon aurolineatum Cuvier, Scarus croicensis (Bloch), Sparisoma aurofrenatum (Valenciennes), and Auxis thazard (Lacepede). All except Lutjanus apodus, Ocyurus chrysurus, and Caranx hippos are believed to be new records of infection by any haemogregarine. Haemogregarines (Protozoa: Sporozoa: Coccidia: Adeleidae) are the most common blood parasites found in marine fishes. None of their vectors is known and, therefore, as yet no complete life history of them has been worked out. The effect they may have upon the health of fishes, and whether or not they may be a factor in the periodic disappearance of commercially important species from a given area, are also unknown. The first haemogregarines of marine fishes in North America were reported from eastern Canada by Fantham et al. (1942). Laird (1961) also described a new species, Haemogregarina irkalukpiki, from northern Canada in the sea-run arctic char, Salvelinus alpinus. Saunders (1955, 1958, 1959, 1960, 1964) has described the presence of H. bigemina, and several new species of this genus, from the marine fishes of Florida, Bermuda, Bimini in the Bahamas, and the Red Sea. This paper gives the results of a general survey of the blood parasites of marine fishes from the coastal waters of Puerto Rico. As has been the case with a number of similar surveys elsewhere, only haemogregarines were encountered. The incidence of infection among the Puerto Rican fishes was very light, as has been true in every area the author has studied except the Red Sea (1960). It was hoped that in the Puerto Rican material one or more host species would be found which had a high enough incidence of parasitism by haemogregarines to make possible future experiments upon their vectors and methods of transmission. MATERIALS AND METHODS As is shown in Table I, 1,340 fishes of 126 species, belonging to 47 families and 12 orders, were examined for blood parasites. They were collected from early January through late April; and from Montalva Bay near Guanica as the easternmost point, westward through the La Parguera area to Cabo Rojo, and northward from there along the western coastline of Puerto Rico at El Combate, Mayagiiez 1This research was supported by grant GB2699 from the National Science Foundation. The author's deep thanks for aid in the collecting and identification of fish species go to the Staff of the Institute of Marine Biology of the University of Puerto Rico at Mayagiiez, especially to former Director John E. Randall, Drs. Luis R. Almadovar and Gilbert W. Bane, and Mr. Jorge Rivera L6pez; also to Mr. Donald S. Erdman, Fishery Biologist under Federal Aid to Sport Fish Restoration F-I-R, Department of Agriculture, P.R.; and to Capt. Tom Gifford of the sport-fishing boat Princess Vista Mar of the Clay Jackson Enterprises of Loiza, P.R. Living quarters and laboratory facilities were made available at the field station of the Institute of Marine Biology of the University of Puerto Rico on Isla Magueyes near La Parguera. TRANS. AMER. MICROSC. Soc. 85(2): 193-199. 1966. This content downloaded from 157.55.39.104 on Mon, 20 Jun 2016 06:04:11 UTC All use subject to http://about.jstor.org/terms DOROTHY CHAPMAN SAUNDERS