Biological Atlas of the Arctic Seas 2000: Physical oceanography, hydrochemistry, meteorology, and plankton of the Barents and Kara Seas

Presented are physical and biological data for the region extending from the Barents Sea to the Kara Sea during 158 scientific cruises for the period 1913-1999. Maps with the temporal distribution of physical and biological variables of the Barents and Kara Seas are presented, with proposed quality control criteria for phytoplankton and zooplankton data. Changes in the plankton community structure between the 1930s, 1950s, and 1990s are discussed. Multiple tables of Arctic Seas phytoplankton and zooplankton species are presented, containing ecological and geographic characteristics for each species, and images of live cells for the dominant phytoplankton species.

Physical and ultrastructural basis of blue leaf iridescence in two neotropical ferns.

Iridescent blue leaf coloration in two neotropical ferns, Danaea nodosa (L.) Sm. (Marattiaceae) and Trichomanes elegans L. C. Rich. (Hymenophyllaceae), is caused by thin film constructive interference. The ultrastructural basis for the film in D. nodosa is multiple layers of cellulose microfibrils in the adaxial cell walls of the adaxial epidermis. The apparent helicoidal arrangement of the fibrils is analogous to similar color production in arthropods. In T. elegans the blue-green coloration is caused by the remarkably uniform thickness and arrangement of grana in specialized chloroplasts adjacent to the adaxial wall of the adaxial epidermis. The selective advantage of this color production, if any, is unknown but apparently different from that previously studied in Selaginella.

Ocean acidification and the loss of phenolic substances in marine plants

Rising atmospheric CO2 often triggers the production of plant phenolics, including many that serve as herbivore deterrents, digestion reducers, antimicrobials, or ultraviolet sunscreens. Such responses are predicted by popular models of plant defense, especially resource availability models which link carbon availability to phenolic biosynthesis. CO2 availability is also increasing in the oceans, where anthropogenic emissions cause ocean acidification, decreasing seawater pH and shifting the carbonate system towards further CO2 enrichment. Such conditions tend to increase seagrass productivity but may also increase rates of grazing on these marine plants. Here we show that high CO2 / low pH conditions of OA decrease, rather than increase, concentrations of phenolic protective substances in seagrasses and eurysaline marine plants. We observed a loss of simple and polymeric phenolics in the seagrass Cymodocea nodosa near a volcanic CO2 vent on the Island of Vulcano, Italy, where pH values decreased from 8.1 to 7.3 and pCO2 concentrations increased ten-fold. We observed similar responses in two estuarine species, Ruppia maritima and Potamogeton perfoliatus, in in situ Free-Ocean-Carbon-Enrichment experiments conducted in tributaries of the Chesapeake Bay, USA. These responses are strikingly different than those exhibited by terrestrial plants. The loss of phenolic substances may explain the higher-than-usual rates of grazing observed near undersea CO2 vents and suggests that ocean acidification may alter coastal carbon fluxes by affecting rates of decomposition, grazing, and disease. Our observations temper recent predictions that seagrasses would necessarily be "winners" in a high CO2 world.

TABLE 2. - List of species of Garamaridea and Corophiidea collected in southern Tierra del Fuego

Species richness and faunistic affinities of gammaridean and corophiidean amphipods from southern Tierra del Fuego were studied. The material was collected with dredges and grabs at 7 locations (15 sampling stations) in a range of 5 to 35 m depth. A total of 61 species belonging to 20 families and 43 genera were identified. The genera Cephalophoxoides, Ceradocopsis and Photis are reported for the first time from the Magellan region and 3 species belonging to Atyhts, hchyrocerus and Photis appear to be new to science. Most of the species collected belong to Phoxocephalidae, whereas most individuals were contained in the Stenothoidae and Lysianassidae s.l. The analysis of the faunistic affinities showed that 16 species (39%) are endemic to the Magellan region, 9 species (22%) extend to the south, 5 species (12.2%) to the north and 5 other species (12.2%) to both the north and south. In addition, 6 species extend beyond the Magellan region as far as Oceania.

Distribution of diatoms, coccolithophores and planktic foraminifera in the Arabian Sea

The distribution of diatoms, coccolithophores and planktic foraminifers mirrored the hydrographic and trophic conditions of the surface ocean (0-100 m) across the upwelling area off the Oman coast to the central Arabian Sea during May/June 1997 and July/August 1995. The number of diatoms was increased in waters with local temperature minimum and enhanced nutrient concentration (nitrate, phosphate, silicate) caused by upwelling. Vegetative cells of Chaetoceros dominated the diatom assemblage in the coastal upwelling area. Towards the more nutrient depleted and stratified surface waters to the southeast, the number of diatoms decreased, coccolithophore and planktic foraminiferal numbers increased, and floral and faunal composition changed. In particular, the transition between the eutrophic upwelling region off Oman and the oligotrophic central Arabian Sea was marked by moderate nutrient concentration, and high coccolithophore and foraminifer numbers. Florisphaera profunda, previously often referred as a 'lower-photic-zone-species', was frequent in water depths as shallow as 20 m, and at high nutrient concentration up to 14 µmol NO3/l and 1.2 µmol PO4/. To the oligotrophic southeast of the divergence, cell densities of coccolithophores declined and Umbellosphaera irregularis prevailed throughout the water column down to 100 m depth. In general, total coccolithophore numbers were limited by nutrient threshold concentration, with low numbers (<10*10**3 cells/l) at high [NO3] and [PO4], and high numbers (>70*10**3 cells/l) at low [NO3] and [PO4]. The components of the complex microplankton succession, diatoms, coccoliths and planktic foraminifers (and possibly others), should ideally be used as a combined paleoceanographic proxy. Consequently, models on plankton ecology should be resolved at least for the seasonality, to account for the bias of paleoceanographic transfer calculations.

Phytoplanktonic microfossil groups of sediments from the South and Equatorial Atlantic

Individual planktonic microfossil species, or assemblage groups of different species, are often used to, qualitatively and/or quantitatively, reconstruct past (sub)surface-water conditions of the world's oceans and seas. Until now, little information has been available on the surface sediment distribution patterns and paleoenvironmental reconstruction potential of coccolith, calcareous dinoflagellate cyst and organic-walled dinoflagellate cyst assemblages of the South and equatorial Atlantic, especially at the species level. This paper (i) summarizes the distributions of these three phytoplanktonic microfossil groups in numerous Atlantic surface sediments from 20°N-50°S and 30°E-65°W and determines their relationship with the physicochemical and trophic conditions of the overlying (sub)surface-waters, and (ii) determines the synecology of the three phytoplankton groups by carrying out statistical analyses (i.e. detrended and canonical correspondence analyses) on all groups simultaneously. Ecological relationships are additionally strengthened by statistically comparing the distribution patterns of the phytoplankton groups with those of planktonic foraminifera (Pflaumann et al. 1996; Niebler et al. 1998), as the ecological preferences of the latter are much better known. Many of the analyzed phytoplanktonic microfossil species or groups of species in the surface sediments do show restricted distributions which primarily reflect the environmental conditions of the upper water masses above them (e.g. sea-surface temperature, productivity, stratification). The acquired 'reference' data sets are large and diverse enough to allow future development of transfer functions for the reconstruction of past surface-water conditions, and show that there is still an enormous paleoenvironmental reconstruction potential concealed in many fossil coccolith and dinoflagellate cyst assemblages.

Landscape metrics as indicators of coastal morphology and its use in ecological niche modelling of seagrass species

Dependence of some species on landscape structure has been proved in numerous studies. So far, however, little progress has been made in the integration of landscape metrics in the prediction of species associated with coastal features. Specific landscape metrics were tested as predictors of coastal shape using three coastal features of the Iberian Peninsula (beaches, capes and gulfs) at different scales. We used the landscape metrics in combination with environmental variables to model the niche and find suitable habitats for a seagrass species (Cymodocea nodosa) throughout its entire range of distribution. Landscape metrics able to capture variation in the coastline enhanced significantly the accuracy of the models, despite the limitations caused by the scale of the study. We provided the first global model of the factors that can be shaping the environmental niche and distribution of C. nodosa throughout its range. Sea surface temperature and salinity were the most relevant variables. We identified areas that seem unsuitable for C. nodosa as well as those suitable habitats not occupied by the species. We also present some preliminary results of testing historical biogeographical hypotheses derived from distribution predictions under Last Glacial Maximum conditions and genetic diversity data.

Comunidades de crustáceos decápodos asociados a fondos superficiales de fanerógamas marinas y su relación con biotopos colindantes en el sur de España

La Zona de Especial Conservación (ZEC) de Calahonda, se encuentra localizada en una zona de transición entre aguas atlánticas y mediterráneas, en la cual además coinciden tres regiones biogeográficas (el mar de Alborán, dentro de la provincia Mediterránea, la plataforma atlántica europea del Sur y los Afloramientos Saharauis, ambas dentro de la provincia Lusitánica). Todo esto junto con las características oceanográficas de la zona (gran influencia de agua atlántica y afloramientos casi permanentes) hacen que sea una de las zonas más biodiversas de toda Europa. Los constantes afloramientos de la zona junto con la influencia atlántica hacen que esta zona sea unas de las más productivas de todo el mediterráneo. Esta alta productividad es la responsable, en parte, de la baja claridad de sus aguas. Esto hace que en el ZEC”Calahonda”, encontremos praderas de fanerógamas como: el endemismo mediterráneo Posidonia oceanica o Cymodocea nodosa con una estructura fragmentada y con unos parámetros fenológicos característicos (alta densidad de haces y hojas cortas) en comparación con otras praderas mediterráneas. Por lo tanto, sería interesante estudiar como esta configuración de las praderas y la influencia atlántica del ZEC”Calahonda” podrán influir en las comunidades bentónicas asociadas a ellas y su dinámica temporal. Para ello se eligieron los crustáceos decápodos, pues son un grupo muy abundante y diverso tanto en aguas someras como profundas, y además su alta movilidad nos permitiría estudiar el flujo de especies e individuos entre los diferentes hábitats. Además de las praderas de fanerógamas antes citadas, también se estudiaron los fondos de macroalgas fotófilas, pues son los más abundantes en términos de cobertura dentro del ZEC”Calahonda”. Cada una de las asociaciones de decápodos ligadas a cada una de los tres hábitats estudiados, presentaron una composición faunística característica. Si bien es verdad que también compartieron un gran número de especies. En cuanto a la tendencia temporal de las asociaciones, cada una tuvo una dinámica diferente. Así, las asociaciones ligadas a C. nodosa presentaron una dinámica temporal fuertemente correlacionada con la fenológica de la planta. Mientras que las asociaciones ligadas a P. oceanica y los fondos de macrolagas, mostraron una dinámica temporal independiente de la fenología, siendo los eventos de reclutamiento, la temperatura del agua y la complejidad estructural del hábitat, entre otras, las variables responsables de ella. La estructura en mosaico de los fondos del ZEC”Calahonda”, formados por rodales de P. oceanica, C. nodosa y fondos de macroalgas, generan un hábitat con una alta complejidad estructural. El cual permite un flujo de especies entre ellos, generando unas asociaciones de decápodos muy diversas y estables en el tiempo.