Human myiasis in Bahía Blanca, Argentina. Period 2000 / 2005

Myiasis is the infestation of live human and vertebrate animals with dipterous larvae which, at least for a short period, feed on the host's dead or living tissue, liquid body-substance, or ingested food. The objective of this study was to identify the flies producing myiasis in Bahía Blanca city, Argentina, from 01/03/2000 to 31/05/2005. Seventeen clinical cases were studied. The larvae obtained from lesions were forwarded from laboratories and from public and private hospitals. Part of the larvae were fixed in alcohol 70 masculine and processed according to the Mazza & J?rg technique (1939). The other part continued growing in flasks with meat in laboratory conditions to obtain the adults. The etiological agents of myiasis were identified by observing the diagnostic characteristics of the larvae III and of the adults, and by using taxonomic keys. Myiasis was produced by Cochlyiomia hominivorax (Coquerel) in thirteen of the cases and by Phaenicia sericata (= Lucila sericata) (Meigen) (Diptera: Calliphoridae) in the other four. The cases were traumatic and aural myiasis and happened from December to March. The ages of patients were four to eighty-six years and 76.5% of the cases occurred in male patients. Given the aggressiveness of these larvae, mainly C. hominivorax, in causing human myiasis, the importance of specific and quick diagnosis and of adequate treatment must be acknowledged.     

Seasonal succession of Copepoda in the Bahía Blanca estuary

The abundance and species composition of Copepoda with respect to other mesozooplanktonic groups were studied at the harbour of Ingeniero White in the inner zone of the Bahfa Blanca estuary, between July 1990 and August 1991. Maximal copepod abundances of 4.7 × 10 m^–3 and 4.9 × 10 m^–3 were observed in January 1991 and May 1991, respectively. Minimal abundances of 6 m^–3 were found in June 1990. Acartia tonsa was present throughout the year with high dominance in summer-autumn (December to May). Eurytemora affinis was present from July to October 1990 (first pulse) and from July to September 1991 (second pulse). Euterpina acutifrons was most abundant during spring 1990, whereas Paracalanus parvus was most abundant during winter-spring (July–October) 1990 and April–May 1991. The rest of the copepods were observed during winter and spring 1990 and July–August 1991. Calanoides carinatus and Labidocera fluviatilis, both species from the outer estuarine waters, were only found on two sampling dates. The proportion of meroplanktonic forms was high in certain months of the annual period considered. Differences between the copepod seasonal succession studied here and those observed during several years in the 1980's are discussed.     

Feeding habits of the juvenile striped weakfish, Cynoscion guatucupa Cuvier 1830, in Bahía Blanca estuary (Argentina): seasonal and ontogenetic changes

The aim of this study was to analyze the feeding habits of the juvenile striped weakfish, Cynoscion guatucupa Cuvier, from Bahía Blanca estuary, Argentina. C. guatucupa is one of the most important regional fishing resources although in the last 10 years landings have greatly decreased. The year class strength of fish as well as stock size and yield are determined during the early life stages. Knowledge about the diet of young C. guatucupa may therefore contribute to our better understanding of the influence that the changes occurring in the biota of the estuary exert on the abundance fluctuations of this species. To this end, we investigated the ontogenetic and seasonal dietary changes of C. guatucupa between 1.00 and 12.99 cm total length (age 0+), and we related them to changes in habitat use and prey selection. Two dietary shifts were found during ontogeny. The first shift, at approximately 4 cm total length, involved a change from demersal-pelagic prey (mysid shrimps) to demersal-benthic prey (Peisos petrunkevitchi Burkenroad). The second shift, at approximately 8 cm total length, involved a progressive increase in ichthyophagy (mainly an increase consumption of the Argentine anchovy Engraulis anchoita Hubbs & Marini). Seasonal dietary changes were also found. They evidenced the changes in the availability of organisms. In autumn, the chaetognath Sagitta friderici Ritter-Zahoni, P. petrunkevitchi, and E. anchoita were the dominant prey items; in winter, the copepod Labidocera fluviatilis Dahl along with S. friderici, mysids, and P. petrunkevitchi constituted the majority of the diet; and, in summer, mysids were the most important prey item consumed. Selectivity data showed that whereas some prey items, such as the copepods Acartia tonsa Dana and Paracalanus parvus (Claus) and S. friderici, were consistently negatively selected by all size classes throughout the year, other prey items, such as fish larvae, mysids, and P. petrunkevitchi,were selected in one season and avoided in another. Additional dietary seasonal differences observed in our research indicate that the limited food supply and the low water temperatures are limiting factors for winter juveniles in BahÕa Blanca estuary. These factors may also directly influence the more-than-10 cm total length seaward migration of large numbers of C. guatucupa that is registered at the end of every autumn.     

Characterization of Microbial Mats from a Siliciclastic Tidal Flat (Bahía Blanca Estuary,Argentina)

Biofilms and microbial mats cover the tidal flats of the central zone of the Bahía Blanca estuary (Argentina), creating extensive layers. The objective of this study was to characterize the microphytobenthic communities in these biofilms and mats from sediment cores taken in March, June, September and December 2010. Microorganisms were identified and enumerated by microscopy, and their biomass (chlorophyll a, biovolume) quantified at two different stations in the lower supratidal zone, located ～210 m apart from each other (namely S1 and S2). Additionally, the colloidal carbohydrates produced by these microbial communities were quantified, together with physical parameters such as temperature, granulometry, moisture and organic matter content of the sediment layers that comprise a typical epibenthic mat. On the other hand, changes in biomass and colloidal carbohydrate content were studied through a half-tidal cycle (7 h). There were significant seasonal differences in microphytobenthic biovolume (P < 0.001) with a considerably lower biomass in summer, but no significant differences in microalgal biovolume between stations (P = 0.454). Cyanobacterial biomass (largely composed of the filamentous Microcoleus chthonoplastes) was dominant on all dates at both stations, followed by pennate diatoms. Chlorophyll a and colloidal carbohydrate contents in sediment presented a similar pattern to that of microalgal biovolume; with a 5-fold variation in chlorophyll a for S1 between consecutive sampling events on September and December. There were significant differences between sampling dates in colloidal carbohydrates (P < 0.001) with the lowest values recorded during fall and winter; conversely there were no significant differences between stations (P = 0.324). Silt was the dominant sediment fraction at S1 while sand dominated throughout the uppermost 20 mm at S2. Chlorophyll a contents did not show significant differences throughout a half-tidal cycle, likely the product of vertical migration along the section sampled. Conversely, the content of colloidal carbohydrates varied 5-fold, showing a significant (P < 0.001) and steady increase with time of exposure to air and pointing to the rapid metabolic rates of the community. In conclusion, the microphytobenthic community of the Bahía Blanca estuary presented marked seasonality in its biological parameters and overall physiognomy, also showing elevated metabolic rates when subject to tidal fluctuations.     

On the age and growth of flounder Paralichthys orbignyanus (Jenyns, 1842) in Bahía Blanca Estuary, Argentina

Estimates of age and growth of flounder Paralichthys orbignyanus (Jenyns,1842) were made by analysing fish from commercial catches in Bahía Blanca estuary (39° LS). A total of 823 fish caught by fishing fleets operating in the estuary were collected between February 1997 and January 1998. Age was determined via scale reading and growth estimation parameters using von Bertalanffys equation. Annulus formation occurred in August. The age for the total population, which ranged from 7.7 to 87.5 cm TL was 0–7. Age ranged from 0 to 6 years (21.5–71.9 cm TL) in males and from 0 to 7 years (24.9–87.5 cm TL) in females. Length–weight relationships were W(g)=0.0093 L(cm) exp. 3.03 for the total population, W(g)=0.0147 L(cm) exp. 2.91 for females, and W(g)=0.0168 L(cm) exp. 2.87 for males, respectively. As from age three, females were longer and heavier than males. The growth parameters estimated for the total population, for females and for males were L=83.29, 79.66, and 46.11 cm, respectively; k values were 0.18, 0.23, and 0.92, respectively, and t₀ values were –1.87; –1.54, and –0.62, respectively. Similarly to other flounders,P. orbignyanus is a typical inhabitant of estuaries and coastal regions. Adults stay in the study area mainly during spring and summer, they go outside or offshore during the spawning period and then they return to the estuary for feeding and recovering.     

Bloom of Gymnodinium catenatum in Bahía Santiago and Bahía Manzanillo, Colima, Mexico

Gymnodinium bloom events are of concern, since they produce toxins, which have unfavorable consequences to marine ecosystems, human health and the economy. This report describes the physico-chemical conditions that were present during the algal bloom event on May 2010 in Bahía Manzanillo and Bahía Santiago, Colima, Mexico. For this, seawater nutrient analysis, phytoplankton counts, identification, and toxicity tests were undertaken. Nutrients in seawater were determined using colorimetric techniques, the higher concentrations (8.88 microM DIN, 0.78 microM PO4 and 24.34 microM SiO2) were related with upwelling waters that promoted the algal bloom that began after registering the year lowest sea-surface temperature, favoring the rapid growth of G. catenatum (up to 1.02 x 10(7) cells/L). Phytoplankton counting was carried out using sedimentation chambers and cells enumerated on appropriated area. The bloom persisted in the bays for approximately two weeks and was associated with toxicity (determined with HPLC) in local oysters (1525.8 microg STXeq/100g), and in phytoplankton (10.9 pg STXeq/cells) samples. Strong variations in cell toxicity (1.4 to 10.9pg STXeq/cells), most likely reflected the availability of inorganic nutrients. The toxin profile of the phytoplankton samples consisted of 11 toxins and resembled those recorded for several strains of G. catenatum isolated from other coastal areas of Mexico.     

Contribution of planktonic and detritic fractions to the natural diet of mesozooplankton in Bahía Blanca Estuary

The pike, Esox lucius Linnaeus, is a predatory fish that supports important fisheries and could substantially impact prey populations around the temperate northern hemisphere. Consumption of prey by pike is most readily estimated using the energy budget to calculate food intake indirectly using estimates of growth rate and metabolism. Resting metabolic rate, R _s, is a particularly important component of such calculations. Here, the available estimates of R _s are reviewed and compared. Scaling coefficients for variation with body mass are consistent between the two studies in which they have been derived (0.81, 0.82). However, the effect of temperature on R _s markedly varies among studies (Q ₁₀ from 1.73 to 4.80). There is substantial variation in R _s (twofold to fourfold) among studies when temperature and fish size are accounted for. This variation is shown to have a large effect on energy budget calculations of energy intake and to be sufficient to account for imbalances in published budgets. These effects depend on age of pike and season; in one energy budget model, a 50% reduction in R _s resulted in decrease of 19–42% in estimated energy intake of pike. Potential causes of among-study variation in R _s are discussed and it is recommended that standard techniques by applied in the future to differentiate between genuine biological variation among populations and experimental factors. Guest editors: J. M. Farrell, C. Skov, M. Mingelbier, T. Margenau & J. E. Cooper International Pike Symposium: Merging Knowledge of Ecology, Biology, and Management for a Circumpolar Species     

Effect of the meteorological parameters on the <Emphasis Type="Italic">Olea europaea</Emphasis> L. pollen season in Bahía Blanca (Argentina)

Olea europaea is one of the most prevalent aeroallergens causing allergenic reactions in the city of Bahía Blanca, Argentina. The aim of this study was to evaluate the influence of meteorological factors on the pollen season of Olea europaea L. The aerobiological analysis was performed over an 11-year period in the city. Sampling was carried out with a Rotorod model 40 volumetric impact sampler. The pollen season started in the middle of October and showed the highest values between 16 October and 24 November. A marked difference was noted over the years of this study, especially in 2005 and 2008, due to a significant decrease in the precipitation during the months prior flowering and high temperatures during the pollen season. A decreasing trend of pollen index during the study period coincided with a reduction in the precipitation from June to October (winter and spring). As expected, the air temperature prior to the onset of flowering is of great importance in determining the start of the pollen season.     

Breaching biogeographic barriers: the invasion of <Emphasis Type="Italic">Haynesina germanica</Emphasis> (Foraminifera,Protista) in the Bahía Blanca estuary,Argentina

Large populations of the living benthic foraminifera Haynesina germanica (Ehrenberg 1840) are reported for the first time from marsh and intertidal mud flat sediments of the Bahía Blanca estuary (Argentina). Maximum abundance of living specimens was recorded in shallow intertidal environments. The species was previously recorded from many European and North American shallow-water coastal settings, but has not been documented from Argentina. Comparative faunal assemblage analysis from dated core sample material from within the Bahía Blanca estuary shows that the species has not been present for at least the last 8,200 years. This supports the hypothesis that the species has been accidentally introduced outside its natural range as a probable result of ballast water and/or shipping activities. This study is the first report of a successful invasion of non-indigenous benthic foraminifera to the South Atlantic coast of Argentina. The introduction of nonnative foraminiferal species provides new evidence that human-mediated breaching of biogeographic barriers, will ultimately result in the biotic homogenization of foraminiferal intertidal faunal assemblages.     

Airborne pollen calendar of Buca–Izmir, Turkey

This communication presents the level ofpollen in the atmosphere of Buca–Izmir, Turkey.The evaluation includes qualitative as well asquantitative results. Studies were carried outduring 1996–1997 using gravimetric method. Datawas recorded from lower (BUL. 1.60 m) andhigher (BHL. 20 m) levels. Aeropalynologicalresults revealed that the atmosphere in thisarea abounds in pollen from 55 taxa out ofwhich 24 are woody and 31 herbaceous. At bothlevels plant groups with higher pollendensities per square centimeter were trees(BHL. 89%, BUL. 73.7%), other herbs (BHL.6.6%, BUL. 20.4%), Gramineae (BHL. 3.8%,BUL. 4.9%) and unidentified taxa (BHL. 0.6%,BUL. 1%) respectively. However, at lowerlevel Pinus, Quercus, Oleaceae,Morus, Centaurea, Gramineae,Chenopodiceae/Amaranthaceae showed highestconcentration; whereasCupressaceae/Taxaceae, Quercus,Gramineae, Chenopodiaceae/Amaranthaceae andPlantago were dominant at higher level.The concentration of allergic taxaChenopodiaceae/Amaranthaceae, Cupressaceae/Taxaceae; Gramineae, Morus, Oleaceae, Pinus, Plantago and Quercus was highin the atmosphere of the study area. The pollencalendar of the area has been prepared inrelation to the atmospheric parameters.     

Species composition,richness, and distribution of marine bivalve molluscs in Bahía de Mazatlán,México

We describe the composition and distribution of bivalve molluscs from the sandy and rocky intertidal and the shallow subtidal environments of Bahía de Mazatlán, México. The bivalve fauna of the bay is represented by 89 living species in 28 families, including 37 new records and four range extensions: Lithophaga hastasia, Adula soleniformis, Mactrellona subalata, and Strigilla ervilia. The number of species increases from the upper (44) and lower intertidal (53) to the shallow subtidal (76), but only 11 (17%) have a wide distribution in the bay (i.e., found in all sampling sites and environments). The bivalve assemblages are composed of four main life forms: 27 epifaunal species, 26 infaunal, 16 semi-infaunal, and 20 endolithic. A taxonomic distinctness analysis identified the sampling sites and environments that contribute the most to the taxonomic diversity (species to suborder categories) of the bay. The present work increased significantly (31%) to 132 species previous inventories of bivalves of Bahía de Mazatlán. These species represent 34% of the bivalve diversity of the southern Golfo de California and approximately 15% of the Eastern Tropical Pacific region.     

Food and Feeding Habits of Flounder <Emphasis Type="Italic">Paralichthys Orbignyanus</Emphasis> (Jenyns, 1842) in Bahía Blanca Estuary,Argentina

Specimens of flounder Paralichthys orbignyanus (Jenyns, 1842) were collected in Bahía Blanca estuary between February 1997 and January 1998, and their feeding habits were examined in relation to season and size class. The stomach contents of 823 specimens, ranging from 70 to 875 mm total length, were analysed. Their diet included organisms from 17 taxa. The highest vacuity index values were found during autumn and winter. The stomach fullness index indicated that flounders increased their feeding activity between October and March, reaching a highest point in February and decreasing after February. Fish were the primary prey item in frequency, number and weight, followed by crustaceans, such as shrimps and crabs. A seasonal and size class variation was detected in the diet. During summer all-size flounders consumed mainly fish. In autumn, for all-size classes the main food were fish and crustaceans even though fish were dominant in terms of biomass. In spring, crustaceans (mysids Arthromysis magellanica (Cunningham), shrimps Artemesia longinaris Bate, and prawns Pleoticus muelleri (Bate)) were the dominant prey in terms of number and biomass for flounders ≤ 450 mm TL. Size classes larger than 451 mm TL fed on crustaceans and fish though the most important prey item in terms of biomass was fish. In Bahía Blanca estuary,P. orbignyanus evidenced mainly an ichthyophagou – carcinophagous diet. The results collected from the present study lead to conclude that P. orbignyanus shows, in this region, a clear preference for fish.     

Airborne pollen concentration in Ankara,Turkey 1990–1993

Atmospheric pollen was collected with a Burkard spore trap in Ankara, Turkey, from January 1990 to January 1993. A total of 135.787 grains/m³ belonging to 47 taxa were observed. The local pollen season started in February in 1990 and 1991 and in March in 1992. Relatively low pollen concentrations were recorded in 1990 and 1992, probably because of precipitation and low wind speed in the spring. A relatively high pollen concentration was recorded in 1991 which could be caused by higher wind speed in the spring and more precipitation during the winter. Cupressaceae/Taxaceae, Pinaceae, Gramineae, Betula, Moraceae, Platanus, Populus, Acer, Quercus, Chenopodiaceae/Amaranthaceae, Plantago, Rumex are found to be the dominant pollen types in the atmosphere in Ankara. The pollen composition generally reflects the vegetation of gardens, parks and roadsides, while the natural steppe vegetation of the area around Ankara is not properly represented.     

Shifts in the seasonal distribution of deaths in Australia, 1968–2007

Studies in temperate countries have shown that both hot weather in summer and cold weather in winter increase short-term (daily) mortality. The gradual warming, decade on decade, that Australia has experienced since the 1960s, might therefore be expected to have differentially affected mortality in the two seasons, and thus indicate an early impact of climate change on human health. Failure to detect such a signal would challenge the widespread assumption that the effect of weather on mortality implies a similar effect of a change from the present to projected future climate. We examine the ratio of summer to winter deaths against a background of rising average annual temperatures over four decades: the ratio has increased from 0.71 to 0.86 since 1968. The same trend, albeit of varying strength, is evident in all states of Australia, in four age groups (aged 55 years and above) and in both sexes. Analysis of cause-specific mortality suggests that the change has so far been driven more by reduced winter mortality than by increased summer mortality. Furthermore, comparisons of this seasonal mortality ratio calculated in the warmest subsets of seasons in each decade, with that calculated in the coldest seasons, show that particularly warm annual conditions, which mimic the expected temperatures of future climate change, increase the likelihood of higher ratios (approaching 1:1). Overall, our results indicate that gradual climate change, as well as short-term weather variations, affect patterns of mortality.     

Species composition and seasonal succession of saprophagous calliphorids in a rural area of Córdoba: Argentina

During 2004, four experiments were carried out, one each season, in order to determine the species composition and seasonal dynamics of Calliphoridae in a rural area of Córdoba (Argentina). Two pigs (Sus scrofa L.), weighing approximately 8 Kg each, were used in each experiment. They were killed with a blow to the head and immediately placed in a variant of the Schoenly et al. (1991) trap. One pig was exposed in the shade and the other one under direct sunlight. The insect fauna was collected daily during the four first weeks and every two or three days thereafter. A total of 16.609 adults of Calliphoridae were collected, and later on identified as one of the following seven species: Chrysomya albiceps (Wiedemann), Chrysomya megacephala (Fabricius), Phaenicia sericata (Meigen), Phaenicia eximia (Wiedemann), Cochliomyia macellaria (Fabricius), Sarconesia chlorogaster (Wiedemann) and Calliphora vicina Robineau-Desvoidy. C. albiceps was the dominant species in summer, autumn and spring, being replaced in winter by C. vicina, S. chlorogaster and P. sericata. The analysis of the seasonal distribution of the species revealed that the greater incidences are in the months of summer, autumn and spring.     

Presence of Cochlodinium catenatum (Gymnodiniales: Gymnodiniaceae) in red tides of Bahía de Banderas, Mexican Pacific

The evolution of an ichthiotoxic algal bloom caused by the dinoflagellate Cochlodinium catenatum was studied from July to December 2000. The abnormal multiplication of this dinoflagellate occurred in the form of a discoloration spreading between a temperature and salinity interval of 25-32 degrees C and 33-35 ups, respectively. The density of C. catenatum reached 10 841 cells ml(-1). The event was observed in large areas of Banderas Bay affecting 13 fish species, whose massive killing was due to suffocation (gill obstruction and excessive mucus production). The human population around the area did not present respiratory affections or skin irritation. The C. catenatum measurements suggest a hologamic and heterothalic reproduction. Their morphological characteristics suggest that C. polykrikoides, C. heterolobatum and C. catenatum are the same species. It is estimated that the species could be a recent introduction in the Mexican Pacific.     

Diversity of ammonia-oxidizing archaea and bacteria in the sediments of a hypernutrified subtropical estuary: Bahía del Tóbari, Mexico

Nitrification within estuarine sediments plays an important role in the nitrogen cycle, both at the global scale and in individual estuaries. Although bacteria were once thought to be solely responsible for catalyzing the first and rate-limiting step of this process, several recent studies have suggested that mesophilic Crenarchaeota are capable of performing ammonia oxidation. Here we examine the diversity (richness and community composition) of ammonia-oxidizing archaea (AOA) and bacteria (AOB) within sediments of Bahía del Tóbari, a hypernutrified estuary receiving substantial amounts of ammonium in agricultural runoff. Using PCR primers designed to specifically target the archaeal ammonia monooxygenase alpha-subunit (amoA) gene, we found AOA to be present at five sampling sites within this estuary and at two sampling time points (January and October 2004). In contrast, the bacterial amoA gene was PCR amplifiable from only 40% of samples. Bacterial amoA libraries were dominated by a few widely distributed Nitrosomonas-like sequence types, whereas AOA diversity showed significant variation in both richness and community composition. AOA communities nevertheless exhibited consistent spatial structuring, with two distinct end member assemblages recovered from the interior and the mouths of the estuary and a mixed assemblage from an intermediate site. These findings represent the first detailed examination of archaeal amoA diversity in estuarine sediments and demonstrate that diverse communities of Crenarchaeota capable of ammonia oxidation are present within estuaries, where they may be actively involved in nitrification.     

Airborne pollen of Ambrosia in Burgundy (France) 1996–1997

Pollen counts in Burgundy were monitored by means of four Hirst volumetric traps. Their analysis revealed a sharp rise of Ambrosia from 1996 to 1997. The minimum amount of ragweed pollen likely to provoke allergies (13 grains m–3) was reached or exceeded several days every year, but without leading to clinical symptoms. The circadian variation of Ambrosia pollen showed two peaks: the first one in the morning was suggested to coincide with local pollination, although the second one, in the afternoon, seemed to result from a long range transport which was confirmed by the study of wind roses.     

Community structure of zooplankton in the main entrance of Bahía Magdalena, México during 1996

The zooplankton community structure, including copepods, euphausiids, chaetognaths, and decapod larvae, was monitored during six circadian cycles using Bongo net (500 microns mesh net) samples from Bahía Magdalena, on the southwest coast of Baja California, México. Samples were obtained during three oceanographic surveys (March, July, and December 1996) to describe the changes in the zooplankton community structure throughout the main mouth of Bahía Magdalena. The zooplankton community structure showed strong changes with a close relation to environmental conditions. During March, a well-mixed water column with low temperature and salinity indicated an influence of the California Current water and local upwelling processes. During July, temperature increased and a wide salinity range was recorded. The stratification of the water column was intense during summer, enhancing the thermocline. The highest temperatures and salinity were recorded in December, related to the presence of the Costa Rica Coastal Current (CRCC). The thermocline deepened as water temperature increased. A typical temperate community structure with low specific richness dominated by Calanus pacificus, Nyctiphanes simplex, and Acartia clausi and high zooplankton biomass (average 9.3 and 5.5 ml 1000 m-3 respectively) during March and July shifted to a more complex tropical community structure with a low zooplankton biomass in December (average 0.37 ml 1000 m-3). The mouth of Bahía Magdalena has a vigorous exchange of water caused by tidal currents. The zooplankton community structure was not significantly different between the central part of Bahía Magdalena and the continental shelf outside the bay for all months. The results suggest a more dynamic inside-outside interaction of zooplankton assemblages than first thought.     

Asteroidea, Echinoidea y Holothuroidea in shallow bottoms of Bahía de Loreto, Baja California Sur, Mexico

To evaluate echinoderm distribution, abundance and density a double 50 m transect, with a side observation range of 2.5 m was used at each of 11 stations (bimonthly samplings, Aug. 1997-Febr. 1998). In Bahía de Loreto the Phylum Echinodermata consists of 26 taxa. The greatest mean abundance by transect and mean densities in order of importance for Echinoidea were: Echinometra vanbrunti (94.1 +/- 52.9 ind, 0.25 ind/m2), Centrostephanus coronatus (38.15 +/- 9.15 ind, 0.06 ind/m2), Tripneustes depressus (28.68 +/- 6.86 ind, 0.039 ind/m2), Eucidaris thouarsii (10.66 +/- 3.37 ind, 0.025 ind/m2) and Diadema mexicanum (11.75 +/- 4.92 ind, 0.023 ind/m2); for Asteroidea were: Phataria unifascialis, Mithrodia bradleyi and Acanthaster planci. Asteroidea was the dominant class with 12 species, followed by Echinoidea with ten and Holothuroidea was represented by four species.