Number of living and dead foraminifers in the upprmost layer of bottom sediments from the Pacific shelf of South America and environmental characteristics

After death of benthic and planktic foraminifera their tests intensive dissolve in sediments of the upper sublittoral zone (depth 30-60 m) in the highest productivity area of surface water in the northern Peruvian region. Dissolution of fine pelitic ooze is more intensive than of sandy sediments. Rate of dissolution is lower in the lower sublittoral zone (60-200 m) than in the upper part of the zone. Within the upper bathyal zone (300-500 m) dissolution decreases and results to accumulation of carbonate test in this zone. Benthic tests are more abundant than planktic ones. Very poor species composition and a peculiar set of species are characteristic of foraminiferal assemblages found in the sublittoral and upper bathyal zones along the Peruvian coast.

(Table 1) Number of alleles per locus and heterozygosity of Arctic charr (Salvelinus alpinus) populations in Iceland

The ecological theory of adaptive radiation predicts that the evolution of phenotypic diversity within species is generated by divergent natural selection arising from different environments and competition between species. Genetic connectivity among populations is likely also to have an important role in both the origin and maintenance of adaptive genetic diversity. Our goal was to evaluate the potential roles of genetic connectivity and natural selection in the maintenance of adaptive phenotypic differences among morphs of Arctic charr, Salvelinus alpinus, in Iceland. At a large spatial scale, we tested the predictive power of geographic structure and phenotypic variation for patterns of neutral genetic variation among populations throughout Iceland. At a smaller scale, we evaluated the genetic differentiation between two morphs in Lake Thingvallavatn relative to historically explicit, coalescent-based null models of the evolutionary history of these lineages. At the large spatial scale, populations are highly differentiated, but weakly structured, both geographically and with respect to patterns of phenotypic variation. At the intralacustrine scale, we observe modest genetic differentiation between two morphs, but this level of differentiation is nonetheless consistent with strong reproductive isolation throughout the Holocene. Rather than a result of the homogenizing effect of gene flow in a system at migration-drift equilibrium, the modest level of genetic differentiation could equally be a result of slow neutral divergence by drift in large populations. We conclude that contemporary and recent patterns of restricted gene flow have been highly conducive to the evolution and maintenance of adaptive genetic variation in Icelandic Arctic charr.

The number of plastic particles found in estuarine sediment and water samples of five estuaries, Durban, KwaZulu-Natal, South Africa

Widespread disposal of plastics negatively affects biotic and abiotic components of marine systems. Monitoring plastics transitioning through estuaries is vital in assessing terrestrial inputs to oceanic environments. Data on microplastics (particles <= 5mm) in estuaries are scant. This study determined microplastic levels within five estuaries along the Durban coastline and on intervening beaches. Plastics were isolated from estuarine sediment, beach sediment and the surface water of each estuary and characterised. Sediment at the Bayhead area of Durban Harbour was found to contain the highest average plastic concentrations (745.40 ± 129.72 particles per 500ml). Overall an attenuating concentration trend away from the city center was found. Fragments composed the largest percent of plastics (59 %) found in Bayhead, whereas fibers dominated other estuaries (Mdloti - 66 %, uMgeni - 38 %, Isipingo - 45 % and iLovu - 53 %). Plastic particle concentration in estuarine sediment generally increased from larger to smaller size classes. If high input and high retention in the harbour is coupled with high organic and metal pollutant loads, this area can become (if not already) a major environmental hazard.

Census of calcareous nannofossil taxa expressed as percent of total number of individuals counted, ODP Legs 113, 114, 119, 120

Quantitative analysis of upper Eocene-upper Oligocene calcareous nannofossil assemblages from five Ocean Drilling Program sites in the Atlantic and Indian Ocean sectors of the Southern Ocean reveals an abrupt increase in cool-water taxa at the top of magnetic Subchron C13R ca. 35.9 Ma, coincident with an enrichment of ~1? d18O in the planktonic foraminifers at these sites. The synchrony of the abrupt increase in cool-water taxa in the Southern Ocean renders this event a useful biostratigraphic datum at southern high latitudes. This earliest Oligocene cool-water taxa increase was the sharpest and largest during the late Eocene-late Oligocene interval and indicates a drop in surface-water temperature of more than 3°C in the Southern Ocean. This suggests that the earliest Oligocene d18O shift represents primarily a temperature signal; a small portion (~0.2?) is attributable to a global ice-volume increase.