Epiphytic seaweeds of Zostera marina L. from Bahía Concepción, B.C.S., México

Macroalgas epífitas de Zostera marina L. en Bahía Concepción, B. C. S. México

The southern distributional limit of Zostera marina L. and Phyllospadix torreyi Watson for Northwestern México

Se analiza el límite sur de distribución de dos angiospermas marinas en México

Rhodolith forming coralline algae in the Upper Miocene of Santa Maria Island (Azores, NE Atlantic) : a critical evaluation

The Late Miocene Malbusca outcrop is located in the southeastern coast of Santa Maria Island (Azores, NE Atlantic), interspersed in volcanic formations. At ~20 meters above present sea level, a prominent discontinuous layer of rhodoliths seizes with an extension of ~250 meters. This paper presents the first taxonomic record of fossil rhodolith forming coralline algae for the Miocene of the Azores. The preserved taxonomic features used were the following: (1) arrangement of basal filaments, (2) epithallial cells (when observable), (3) presence of cell fusions, (4) conceptacle type, (5) number of cells layers which conceptacle chamber floors are situated below the surrounding thallus surface and (6) for the sporangial pores, the orientation of the filaments around the conceptacle pores. Based on these characters, six taxa were identified encompassing three Corallinaceae (Lithophyllum prototypum, Lithophyllum sp., Spongites sp., Hydrolithon sp.) and one Hapalidaceae (Phymatolithon calcareum and cf. Phymatolithon sp.). An unidentified coaxial thallus was also present, the coaxial construction ascribing the specimens to the genus Mesophyllum or Neogoniolithon. Taxonomic accounts for the identified taxa are described, illustrated and an identification key is provided. The report of L prototypum represents the first Miocene record and the preservation of the specimens is very good. Miocene coralline algae seem very consistent among deposits but some species are relevant for particular areas, like in the Azores

Mesophyllum sphaericum sp. nov. (Corallinales, Rhodophyta): a new maërl-forming species from the northeast Atlantic

Mesophyllum sphaericum sp. nov. is described based on spherical mae¨rl individuals (up to 10 cm) collected in a shallow subtidal mae¨rl bed in Galicia (NW Spain). The thalli of these specimens are radially organized, composed of arching tiers of compact medullary filaments. Epithallial cells have flattened to rounded outermost walls, and they occur in a single layer. Subepithallial initials are as long as, or longer than the daughter cells that subtend them. Cell fusions are abundant. Multiporate asexual conceptacles are protruding, mound-like with a flattened pore plate, lacking a peripheral raised rim. Filaments lining the pore canal and the conceptacle roof are composed of five to six cells with straight elongate and narrow cells at their base. Carposporangial conceptacles are uniporate, protruding, and conical. Spermatangial conceptacles were not observed. Molecular results placed M. sphaericum near to M. erubescens, but M. sphaericum is anatomically close to M. canariense. The examination of the holotype and herbarium specimens of M. canariense indicated that both species have pore canal filaments with elongate basal cells, but they differ in number of cells (five to six in M. sphaericum vs. four in M. canariense). Based on the character of pore canal filaments, M. canariense shows similarities with M. erubescens (three to five celled). The outermost walls of epithallial cells of M. canariense are flared compared to the round to flattened ones of M. erubescens, the latter being widely accepted for the genus Mesophyllum. The addition of M. sphaericum as new mae¨rl-forming species suggests that European mae¨rl beds are more biodiverse than previously understood

Mesophyllum erubescens (Corallinales, Rhodophyta)—so many species in one epithet

The name Mesophyllum erubescens has been applied to protuberant rhodolith specimens which sometimes occur abundantly, as well as to encrusting specimens in tropical and temperate waters in the Western Pacific, Indian and Western Atlantic Oceans. A DNA sequence, representing about 20% of the rbcL gene, was obtained from the 140 year old holotype specimen collected in the Fernando de Noronha Archipelago by the Challenger Expedition. This sequence was identical to field-collected topotype specimens as well as to specimens ranging south along the coast of Brazil. Sequences for psbA from these same Brazilian specimens and specimens from the east coast of Mexico were identical or differed by 1 base pair. In contrast, specimens called M. erubescens based on morpho-anatomical characters in the Pacific Ocean differed from Western Atlantic Ocean specimens by 2.5–13.1%, indicating that these represent numerous distinct species. All reports of non-geniculate coralline species said to be widely distributed across different oceans or in different biogeographic provinces based on morpho-anatomical characters need to be verified by DNA sequence

Patterns of Spatial Variation of Assemblages Associated with Intertidal Rocky Shores: A Global Perspective

Assemblages associated with intertidal rocky shores were examined for large scale distribution patterns with specific emphasis on identifying latitudinal trends of species richness and taxonomic distinctiveness. Seventy-two sites distributed around the globe were evaluated following the standardized sampling protocol of the Census of Marine Life NaGISA project (www.nagisa.coml.org). There were no clear patterns of standardized estimators of species richness along latitudinal gradients or among Large Marine Ecosystems (LMEs); however, a strong latitudinal gradient in taxonomic composition (i.e., proportion of different taxonomic groups in a given sample) was observed. Environmental variables related to natural influences were strongly related to the distribution patterns of the assemblages on the LME scale, particularly photoperiod, sea surface temperature (SST) and rainfall. In contrast, no environmental variables directly associated with human influences (with the exception of the inorganic pollution index) were related to assemblage patterns among LMEs. Correlations of the natural assemblages with either latitudinal gradients or environmental variables were equally strong suggesting that neither neutral models nor models based solely on environmental variables sufficiently explain spatial variation of these assemblages at a global scale. Despite the data shortcomings in this study (e.g., unbalanced sample distribution), we show the importance of generating biological global databases for the use in large-scale diversity comparisons of rocky intertidal assemblages to stimulate continued sampling and analyses

La méthode SIG pour évaluer les herbiers sous-marins de rhodolithe et de sargasses, des habitats indispensables aux espèces marines d'intérêt commercial en Baie de Conception, B.C.S., Mexique

La baie de Conception a été identifiée comme une zone lagonaire côtière très productive non seulement pour la Basse Californie mais aussi pour toute la côte du Mexique. Cependant, le manque de gestion appropriée a entraîné la fermeture de diverses pêcheries comme celle de la coquille Saint-Jacques, Argopecten ventricosus en 1994. Un des principaux défis pour la gestion des ressources côtières est la sélection d\u27habitats spécifiques dédiés à la consommation, en prenant en compte les activités économiques des communautés humaines qui les côtoient. Dans cette étude, les systèmes d\u27information géographiques (SIG) associés à la télédétection ont été mis en place pour évaluer le rôle des rhodolithes et des sargasses, comme habitats essentiels dans la Baie de Conception, pour les espèces commerciales en danger. Des suivis en plongée sur 72 sites sélectionnés au hasard à l\u27intérieur de la Baie ont été effectués pour caractériser les habitats benthiques peu profonds et l\u27abondance des espèces de poissons et d\u27invertébrés ainsi que la biodiversité au cours du printemps 2011. Les analyses montrent que les rhodolithes sont importants pour les regroupements d\u27invertébrés et pour au moins 4 espèces protégées selon la loi mexicaine sur les espèces menacées (NOM-059). Sargassum sp. et les herbiers sous-marins sont aussi des indicateurs pour la diversité mais leur cycle de vie annuel limite le temps pendant lequel ces habitats sont disponibles pour d\u27autres espèces. Les outils SIG ont prouvé leur efficacité pour donner des informations essentielles afin de protéger les habitats critiques comme ceux de rhodolithes, Sargassum sp. ou les herbiers sous-marins pour la récupération et la conservation de la biodiversité.Bahía Concepción was once recognized as a very productive coastal lagoon not only for the Peninsula of Baja California but also for all Mexico. However, lack of proper management has resulted in the closure of various fisheries, such as the Calico scallop, Argopecten ventricosus, in 1994. One of the main challenges for the management of coastal resources is the selection of critical habitats for conservation considering the economic activities of the communities associated with them. This study used Geographic Information Systems (GIS) and remote sensing to assess the roll of rhodoliths and Sargassum spp. as critical habitats in Bahía Concepción for endangered and commercial species. Underwater surveys, on 72 randomly selected sites within the bay, were conducted to characterize the shallow benthic habitats, fish and invertebrate species abundance and richness during the spring of 2011. Analyses show that rhodoliths are important for the invertebrate assemblages and for at least 4 species protected under the Mexican law, NOM-059, for threatened species. Sargassum spp. and seagrass beds are also relevant for diversity but their annual life cycle limits the time when these are available as habitat for other species. GIS tools proved an innovative and effective method to provide essential information to protect critical habitats such as rhodoliths, Sargassum spp. and seagrasses, for the recovery and conservation of diversity.</p

Seasonal variation in the biomass, size and reproduction of the agarophyte &lt;I&gt;Gracilariopsis sp.&lt;/I&gt; (Gracilareaceae, Rhodophyta) from a temperate lagoon in the Pacific coast of Baja California Peninsula, México

Spatial and temporal changes in the population structure and standing crop of Gracilariopsis sp. were studied in the San Ignacio Lagoon during two different sampling periods. Biomass (wet weight, g m–2), thallus size and reproductive state were determined from November 2004 to August 2005. Standing crop was calculated from November 2007 to September 2008. The annual standing crop of Gracilariopsis sp. was estimated to be 1,300 wet tons. We found a seasonal growth cycle during both sampling periods, with the maximum biomass in spring (1,004 wet tons). Biomass was significantly higher near the mouth of the lagoon in shallow and sandy areas. This zone is associated with stronger currents and lower temperatures (annual mean of 20°C). The smallest thalli were found during autumn and winter, and the largest in spring. Senescence and detachment of the plants occurred in summer. Tetrasporangial thalli were the dominant phase in the population throughout the year, followed by vegetative (i.e. showing no reproductive structures) thalli. Gametophytes and carposporophytes were rarely observed during the study. The growth and propagation strategy of Gracilariopsis sp. in San Ignacio Lagoon is characteristic of a clonal population, which strongly suggests this species might be a good alternative for commercial agar production.</p

Macroalgasdel arrecife coralino de Cabo Pulmo-Los Frailes, B.C.S., México

Non-systematic surveys of the Cabo Pulmo-Los Frailes coral reef (1988 to 1994) incrcased to 61 the number of macroalgal species: 11 Chlorophyta, 11 Phaeophyta, and 39 Rhodophyta. Like other reefs, ¡his was dominated by filamentous species that occurred as mutispecies turfs. Unlike other reefs, this assembly is mude up 01' temperate, cosmopolitan and tropical species.Non-systematic surYeys of the Cabo Pulmo-Los Frailes coral reef (1988 to 1994) incrcased to 61 the number of macroalgal species: 11 Chlorophyta, 11 Phaeophyta, and 39 Rhodophyta. Like other reefs, ¡his was dominated by filamentous species that occurred as mutispecies turfs. Unlike other reefs, this assembly is mude up 01' temperate, cosmopolitan and tropical species