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.     

Latitudinal variations of the yield and quality of agar from <Emphasis Type="Italic">Gelidium robustum</Emphasis> (Gelidiales,Rhodophyta) from the main commercial harvest beds along the western coast of the Baja California Peninsula,Mexico

The yield and quality of agar from Gelidium robustum from the main commercial harvest beds along the western coast of the Baja California Peninsula (Mexico) were evaluated within a latitudinal range of about 800 km (31°47′N to 27°05′N). Samples from six locations, Bahía Todos Santos, El Rosario, Isla de Cedros, Islas San Benito, Punta Eugenia, and Bahía Asunción, were analyzed. Bryozoan, protein, and agar content in the seaweed were estimated. The agar quality was determined by the content of 3,6-anhydrogalactose, sulfate, gel strength, and gelling and melting temperature. All the values of these variables were correlated and then with the satellite-derived data of the sea surface temperature (SST), net primary production (NPP), and photosynthetic active radiation (PAR) measured at each harvest bed during the summer months (June, July, and August) of 2000. In the northern and central region, the agar yield was 35% to 37% (Bahía Todos Santos, El Rosario, Isla de Cedros, and Islas San Benito), whereas lower yields were obtained from the southern beds (Punta Eugenia and Bahía Asunción). In contrast, the agar quality increased from the northern to the southern beds. A lower gel strength was obtained from Bahía Todos Santos and El Rosario (268 ± 16 and 205 ± 5 gcm⁻²) with a higher gel strength obtained from Isla de Cedros, Islas San Benito, and Bahía Asunción (384 to 444 ± 25 gcm⁻²). Yield was not correlated with the bryozoan content but was inversely correlated with the protein content in the seaweed. The sulfate content in the agar was inversely correlated with the gel strength and with the melting temperature. The 3,6-anhydrogalactose content showed slight variations among harvested beds. Analysis of satellite-derived data showed an equatorward increase of the SST, NPP, and PAR. The agar content correlated inversely with the equatorward increase of the NPP, whereas agar quality, i.e., gel strength, correlated positively with the NPP and PAR. No significant effects were observed on the yield and quality of agar with the latitudinal change of the SST.     

VARIATIONS OF PSP TOXIN PROFILES DURING DIFFERENT GROWTH PHASES IN GYMNODINIUM CATENATUM (DINOPHYCEAE) STRAINS ISOLATED FROM THREE LOCATIONS IN THE GULF OF CALIFORNIA,MEXICO1

In vitro experiments were performed with Gymnodinium catenatum Graham strains isolated from three locations in the Gulf of California to determine the variability in toxicity and toxin profiles. Strains were cultivated in GSe at 20°C±1°C, 150 μmol photons·m^?2·s^?1 (12:12 light:dark cycle), and harvested during different growth phases. Growth rates were higher than in previous studies, varying between 0.70 and 0.82 day^?1. The highest cell yields were reached at 16 and 19 days, with maximum densities between 1090 and 3393 cells·mL^?1. Bahía de La Paz (BAPAZ) and Bahía de Mazatlán (BAMAZ) were the most toxic (101 pg STXeq·cell^?1), whereas strains from Bahía Concepción (BACO) were the least toxic (13 pg STXeq·cell^?1). A strain isolated from cyst germination was one of the least toxic strains. No significant changes in toxin content with culture age were observed (0.2 and 0.6 pmol paralytic shellfish poisoning·cell^?1). All strains contained neosaxitoxin (NEOSTX), decarbamoyl‐saxitoxin (dcSTX), decarbamoyl‐gonyautoxin‐2,‐3, (dcGTX2‐3), N‐sulfo‐carbamoylsaxitoxin (B1), N‐sulfo‐carbamoylneosaxitoxin (B2), and N‐sulfo‐carbamoylgonyautoxin‐2,‐3 (C1‐2). Bahía Concepción strains had the highest content of C1; BAPAZ and BAMAZ strains had a higher percentage of NEOSTX. Differences in toxin composition with culture age were observed only in BAMAZ and BAPAZ strains. Cultures with a higher percentage of long chains had more NEOSTX, while those with a higher proportion of short chains had a lower content of NEOSTX. Gulf of California strains are characterized by a high proportion of NEOSTX, and seem to have evolved particular physiological responses to their environment that are reflected in the toxin profile, suggesting different populations.     

The role of Ulva spp. as a temporary nutrient sink in a coastal lagoon with oyster cultivation and upwelling influence

Bahía San Quintín is a coastal lagoon with large Ulva biomass and upwelling influence. Previous observations suggest that Ulva has increased recently as a result of oyster cultivation. To evaluate the possible role of Ulva as a temporary nutrient sink, biomass and tissue C, N, and P were determined seasonally. Maximum biomass was present during spring and early summer (1,413–1,160 t (dry)) covering about 400 ha. However, the biomass decreased to 35 t (dry) by winter. The mean annual percentage of Ulva C, N, and P was 28%, 2%, and 0.14%, respectively. This study shows that Ulva can store up to 28 t of N and 2 t of P in Bahía San Quintín during spring–summer. Ulva may be displacing the seagrass Zostera marina subtidal beds. A partial removal of the seaweed would reduce the risk of eutrophication and the displacement of eelgrass beds.     

Ichthyofauna fisheries in Bahía de Navidad,Jalisco, Mexico,associated to the El Niño event 1997-1998

The ichthyofauna fished in Bahía de Navidad, Jalisco, Mexico in the Central Pacific was surveyed during 1998. Six thousand nine hundred and fourty-four organisms of 130 species were caught which weighted 3,231 kg. Nearly 30% of the species belonged to Carangidae. Haemulidae and Sciaenidae. The most important species in number and biomass were Microlepidotus brevipinnins, Caranx caninus and C. caballus. Species number, abundance and biomass fluctuated during the year. The largest number of species was caught in June (61), the minimum in March (33). January had the maximum abundance (1,397 organisms), while the minimum was obtained during August (251). The maximum biomass values were from January (556.5 kg), and the lowest from August (114.7 kg). Eighteen species accumulated 87% of the total abundance, while 20 species represented 86.3% of the biomass. There were large in differences species number, abundance and biomass nets of different mesh size.     

Association patterns of bottlenose dolphins (Tursiops truncatus) in Bahía San Antonio,Argentina

This study aims to investigate the association patterns of a small and resident population of bottlenose dolphins (Tursiops truncatus) in Bahía San Antonio (Argentina), and assess any seasonal variation in view of the reported seasonal variation in the population's grouping behavior. The estimation of social differentiation (S) was 0.29 (SE = 0.08), suggesting a homogenous society. The half‐weight index (HWI) averaged 0.23 (± 0.06), with evidence of long‐term preferred associations. However, data showed seasonal variation in the association patterns. In winter, when large groups were reported in this population, HWI values averaged 0.30 (± 0.09) with no indication of preferred or avoided associations. However, during summer, when group size was generally small, HWI values averaged 0.14 (± 0.07), with an indication of preferred/avoided associations. This study indicates that the social structure of the bottlenose dolphins in Bahía San Antonio seems relatively homogenous and flexible over time, with the formation of a random social network at times when large aggregations are formed, and a more disconnected network made up of strongly connected components when the cost of grouping is high.     

Foliage production of the mangrove from San Andrés Island,Colombian Caribbean coast

Litter fall from a San Andres Island mangrove (12 degrees 32' N, 81 degrees 41' W, Colombian Caribbean coast), was collected monthly (1994-1995) with mesh baskets, keeping results separate for the three species (Rhizophora mangle, Avicennia germinans and Laguncularia racemosa), and taking a sample and a replica per case. Nine sampling sites were selected in two groups of woodlands: one in the inner side behind a sand-bar and the coast road (Mount Pleasant, Salt Creek, Sound Bay and Smith Channel) and a peripheral site, exposed to the waves (Bahía Hooker-Bahía Honda and El Cove). Productivity was greater for all species in the inner group, and higher in the rainy seasons. Rhizophora mangle was the only species contributing reproductive components throughout the year.     

Feeding aggregation and aggressive interaction between bottlenose (Tursiops truncatus) and Commerson’s dolphins (Cephalorhynchus commersonii) in Patagonia,Argentina

We report the first recorded interactions between bottlenose dolphin (Tursiops truncatus) and Commerson’s dolphins (Cephalorhynchus commersonii). The diurnal behavioral patterns of bottlenose dolphins in Bahía Engaño, Argentina, were similar to those described for other coastal populations around the world. The majority of the feeding bouts were recorded near the mouth the Chubut River. When not feeding near the river, bottlenose dolphins generally swam along the coast, and interactions with Commerson’s dolphins were recorded very close to the shore on two occasions during a 3-year period. In the first event, both species were feeding on a fish school. The second interaction was aggressive in nature, involving one juvenile and three adult bottlenose dolphins with several Commerson’s dolphins. Two of the adult bottlenose dolphins attacked the Commerson’s dolphins. We propose that the observed behavior represented defense of the juvenile bottlenose dolphin.

     

Intestinal Acanthocephaladiosis in Olrog's gulls (Larus atlanticus): Profilicollis chasmagnathi as possible cause of death

In 2003 and 2005, mortality events were observed among hatch-year Olrog's gulls (Larus atlanticus) in a breeding colony in the Bahía Blanca estuary, Argentina. Freshly dead chicks were collected for parasitologic and parasite-associated pathologic studies. Profilicollis chasmagnathi was found at various intensities in all of the birds examined (n=28). On gross and histopathologic examinations, severe lesions ranging from intestinal obstruction to complete perforation were present in small and large intestines of the birds. Larval forms of P. chasmagnathi were being found in prey items of L. atlanticus in the study area, which suggests that diet may play a central role in the epidemiology of disease and mortality events in this species.     

The sea urchin Lytechinus variegatus lives close to the upper thermal limit for early development in a tropical lagoon

Thermal tolerance shapes organisms' physiological performance and limits their biogeographic ranges. Tropical terrestrial organisms are thought to live very near their upper thermal tolerance limits, and such small thermal safety factors put them at risk from global warming. However, little is known about the thermal tolerances of tropical marine invertebrates, how they vary across different life stages, and how these limits relate to environmental conditions. We tested the tolerance to acute heat stress of five life stages of the tropical sea urchin Lytechinus variegatus collected in the Bahía Almirante, Bocas del Toro, Panama. We also investigated the impact of chronic heat stress on larval development. Fertilization, cleavage, morula development, and 4‐armed larvae tolerated 2‐h exposures to elevated temperatures between 28–32°C. Average critical temperatures (LT₅₀) were lower for initiation of cleavage (33.5°C) and development to morula (32.5°C) than they were for fertilization (34.4°C) or for 4‐armed larvae (34.1°C). LT₅₀ was even higher (34.8°C) for adults exposed to similar acute thermal stress, suggesting that thermal limits measured for adults may not be directly applied to the whole life history. During chronic exposure, larvae had significantly lower survival and reduced growth when reared at temperatures above 30.5°C and did not survive chronic exposures at or above 32.3°C. Environmental monitoring at and near our collection site shows that L. variegatus may already experience temperatures at which larval growth and survival are reduced during the warmest months of the year. A published local climate model further suggests that such damaging warm temperatures will be reached throughout the Bahía Almirante by 2084. Our results highlight that tropical marine invertebrates likely have small thermal safety factors during some stages in their life cycles, and that shallow‐water populations are at particular risk of near future warming.     

A new estuarine species, Nereis garwoodi (Polychaeta: Nereididae), from Bahía Chetumal, Mexican Caribbean coast

Nereis garwoodi n. sp. is described on the basis of eight syntype specimens (six atokous and two heteronereis) collected in Bahía Chetumal, Mexican Caribbean coast, and the variability in the paragnath numbers in the pharynx is established using 180 specimens; paragnath numbers are I:10(SD = 1.9); II:30 (SD = 2.6); III:41 (SD = 5.2); IV:29 (SD = 3.5), V:1, VI:4, VII-VIII: > 30. Its eyes are big and its longest tentacular cirri reaches setiger 11. A revised key to species of Nereis recorded from the Grand Caribbean Sea is included.     

Echeandia novogaliciana and E. crudeniana (Anthericaceae): Two new species from western Mexico

Echeandia novogaliciana and E. crudeniana are described from western Mexico. Echeandia novogaliciana is known from three populations, one in the state of Nayarit and two in Zacatecas. Likewise, E. crudeniana is known from two populations in the municipality of Bahía de Banderas, Nayarit. For both species, illustrations are provided and morphological relationships with similar species are discussed.     

Alternative Conservation Paradigms and Ecological Knowledge of Small-Scale Artisanal Fishers in a Changing Marine Scenario in Argentina

Human Ecology - We studied conservation paradigms of small-scale artisanal fishers and other actors involved in the conservation of the Bahía Blanca Estuary (BBE)—a Southwestern Atlantic...     

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.     

Length–weight relationships of cryptic reef fishes from the southwestern Gulf of California, Mèxico

Length–weight relationships of 33 cryptic reef fishes from the southwestern Gulf of California were estimated. The most common families were Gobiidae (seven species), Labrisomidae (four), Pomacentridae (three), and Tripterygiidae (three). These are the first length–weight parameters reported for 32 of these species. Specimens were sampled during a comparative ecological study of community structure of fish assemblages associated with coral heads, rocky walls, and artificial reefs in Bahía de La Paz, Baja California Sur. The b values varied between 2.63 and 3.61. New maximum length records for five of the species were established in the study.     

Responses to temperature and salinity by White Mullet Mugil curema: Possible explanation for the population decrease in Baja California Sur

The white mullet Mugil curema is distributed along the Gulf of Mexico and Pacific coasts and constitutes an important food resource in Mexico. However, during recent years the capture of this mugilid has decreased considerably, especially in Bahía and Ensenada de La Paz, Baja California Sur, Mexico. The effects of different levels of temperature (22, 26, and 30°C) and salinity (15, 25, and 35) on the instantaneous growth rate, energy content, and condition factor of early juveniles of Mugil curema were evaluated. Fish showed a lower growth rate, lower body energy content, and a less condition factor when exposed to high salinity and temperature. On the basis to the results obtained and considering the unusual extreme temperatures and salinity registered in Ensenada de La Paz, it is expected low functional performance of juvenile mullets beyond the overfishing might contribute to the population decrease of this resource.     

Do sex and habitat differences in antipredator behavior of Western Sandpipers Calidris mauri reflect cumulative or compensatory processes?

Individuals manage their risk of predation in different ways in different situations. We studied the use of anti-predator behavior by Western Sandpipers (Calidris mauri) at Bahía Santa María, northwestern Mexico, foraging in three habitats that differed in presumed predation danger. Brackish flats are completely open, making them theoretically less dangerous for feeding sandpipers than mangroves and cattail marshes, which have closer visual horizons. Western Sandpipers are sexually dimorphic, with females about 15% longer-billed and 10% heavier than males. We previously showed that male and female sandpipers differed in their habitat choice and relative body mass in ways consistent with differential responses to predation danger (Fernández and Lank in Condor 108:547–557, 2006). Contrary to expectations, however, females were overrepresented in more dangerous habitats. Here, we examine differential usage across habitats and between the sexes of three anti-predator tactics—flock size, density within flocks, and vigilance rate—that may be used cumulatively to reinforce safety, or as trade-offs that compensate for levels of usage of each. We hypothesized, and found, that ordered differences occur among habitats, and that controlling for other factors, females were more cautious than males. For the most part, the use of these three tactics appeared to be cumulative, rather than compensatory. However, with respect to habitat use, birds appeared to compensate for the higher probability of mortality intrinsic to the use of higher-danger habitats by increasing the use of vigilance, foraging in tighter flocks, and maintaining lighter body weights (females only). Thus, both cumulative and compensatory processes operate among anti-predator tactics to determine the net level of safety and trade-off against other factors.     

A new pseudostipule-bearing species of <Emphasis Type="Italic">Aristolochia</Emphasis> (Aristolochiaceae) from Bahía and Espíritu Santo,Brazil

Aristolochia gracilipedunculata, a new pseudostipule-bearing species from Bahía and Espíritu Santo (eastern Brazil), is here described and compared to other species present in this area that belong to the informal group Pseudostipulosae. The new species is easily recognizable by the presence of a long, filiform peduncle, and by the oblong, fimbriate perianth limb with a rounded and emarginate apex. Floral morphology of the new species is also compared to other non-Pseudostipulosae South American species with similar perianth shape.     

Length–weight relationships of 20 fish species from Bahía de Matanchen,in the southeast Gulf of California,Mexico

Length–weight relationship (LWR) parameters were determined for 20 fish species belonging to 14 genera and seven families. The fishes were collected monthly (May 2013 to February 2014) by soft‐bottom trawls in Bahía de Matanchén, southeast of the Gulf of California. Sizes ranged between 5.5 and 36.0 cm total length (TL) and weighed between 1 and 901 g. The allometric coefficient (b) of the LWR varied from 2.638 for Chloroscombrus orqueta to 3.668 for Neopisthopterus tropicus. This is the first report of LWR estimations for 15 of the species.     

Fish larvae association in a Mexican Caribbean bay

Interannual ichthyoplankton variation, was analyzed in Bahía de la Ascensión, Mexico, during December of four consecutive years (1994-1997). A total of 32 families, 35 genera and 21 species of fish larvae were identified. The most abundant fish larvae were the Gobiidae followed by the Callionymidae, Clupeidae and Tetraodontidae. Larval diversity was low when compared with other periods ("dry" and "rainy"). Three spatial associations (internal, medium and external) were found in December 1994 and 1995. In 1996-1997, stations of the inner and outer parts of the bay were mixed. The dominant families characterized most of the faunal associations. Egg density was highest in the external zone of the bay, whereas larvae were most abundant in the inner area. Major factors affecting the fish larval assemblages during December (1994-1997) in Bahía de la Ascensión seem to be related to the nursery areas location and to the tropical fishes reproductive period.