Haemogregarines (Adeleorina) have a high prevalence in turtles. Nevertheless, there is only one Hepatozoon species described that infects Testudines so far; it is Hepatozoon fitzsimonsi which infects the African tortoise Kinixys belliana. Colombia harbours a great diversity of chelonians; however, most of them are threatened. It is important to identify and characterize chelonian haemoparasite infections to improve the clinical assessments, treatments and the conservation and reintroduction programs of these animals. To evaluate such infections for the Colombian wood turtle Rhinoclemmys melanosterna, we analysed blood from 70 individuals. By using the morphological characteristics of blood stages as well as molecular information (18S rRNA sequences), here we report a new Hepatozoon species that represents the first report of a hepatozoid species infecting a semi-aquatic continental turtle in the world. Although the isolated lineage clusters within the phylogenetic clades that have morphological species of parasites already determined, their low nodal support makes their position within each group inconclusive. It is important to identify new molecular markers to improve parasite species identification. In-depth research on blood parasites infecting turtles is essential for increasing knowledge that could assess this potential unknown threat, to inform the conservation of turtles and for increasing the state of knowledge on parasites.

pCO2/pH perturbation experiments were carried out under two different pCO2 levels to evaluate effects of CO2-driven ocean acidification on semi-continuous cultures of the marine diatom Skeletonema pseudocostatum CSA48. Under higher pCO2/lowered pH conditions, our results showed that CO2-driven acidification had no significant impact on growth rate, chlorophyll-a, cellular abundance, gross photosynthesis, dark respiration, particulate organic carbon and particulate organic nitrogen between CO2-treatments, suggesting that S. pseudocostatum is adapted to tolerate changes of ~0.5 units of pH under high pCO2 conditions. However, dissolved organic carbon (DOC) concentration and DOC/POC ratio were significantly higher at high pCO2, indicating that a greater partitioning of organic carbon into the DOC pool was stimulated by high CO2/low pH conditions. Total fatty acids (FAs) were significantly higher under low pCO2 conditions. The composition of FAs changed from low to high pCO2, with an increase in the concentration of saturated and a reduction of monounsaturated FAs. Polyunsaturated FAs did not show significant differences between pCO2 treatments. Our results lead to the conclusion that the balance between negative or null effect on S. pseudocostatum ecophysiology upon low pH/high pCO2 conditions constitute an important factor to be considered in order to evaluate the global effect of rising atmospheric CO2 on primary productivity in coastal ocean. We found a significant decrease in total FAs, however no indications were found for a detrimental effect of ocean acidification on the nutritional quality in terms of essential fatty acids.

We present new records of chondrichthyans recovered from strata of Maastrichtian age of the López de Bertodano Formation, Seymour (=Marambio) Island, and from levels of latest Campanian age of the Santa Marta Formation, James Ross Island, both located in the eastern Antarctic Peninsula. The material from Marambio Island comprises an associated assemblage with the first records of an indeterminate odontaspidid different from Odontaspis, as well as the genera Pristiophorus, Squatina, Paraorthacodus, and the species Chlamydoselachus tatere from the López de Bertodano Formation. Also, the studied section provides a well-constrained age for several taxa already recognized in the López de Bertodano Formation only by scattered samples of Maastrichtian age for the first time. The assemblage from Marambio Island is representative of one of the latest environmental conditions during the end of the Cretaceous in the coastal seas of the Larsen Basin before major changes that began after the K/P boundary. In addition, the finds from James Ross Island comprise the southernmost records of the neoselachians Cretalamna sp., Centrophoroides sp., as well as the holocephalans Callorhinchus sp. and an indeterminate rhinochimaerid, extending the occurrence of some of these taxa into the late Campanian, being their oldest record of the Weddellian Biogeographic Province.

The growth rate response of bacterial communities to the potential increase of dissolved organic matter (DOM) produced by the copepod Acartia tonsa was assessed in experiments conducted in three stations representing three contrasting aquatic environments (coastal embayment, shelf and ocean). Bacterial assemblages were inoculated in filtered seawater where A. tonsa had previously grazed. Utilization of DOM over time was evaluated after the addition of bacterial inoculums as the biomass changes in both ‘control’ and ‘copepod’ treatments. In the embayment and ocean a high bacterial growth was observed in the treatments with seawater where copepod were feeding. Additional field measurements of bacterial, primary production and zooplankton biomass support the idea that bacterial communities living in oceanic environments can be efficient to utilize the newly available substrate. Copepods play a key role not only as conveyors of carbon up through the classical food-web, but also generated significant amounts of bacterial substrate in the microbial loop food-web.

Off central Chile, around 33.5°S, the freshwater discharge of the River Maipo generates a small- to intermediate-size plume, which moves up to the north driven by the daily sea breeze and with localized effects on a costal zone of about 10–15 km. The influence of this river plume motion on abundance patterns of larval barnacles was studied in a ∼12 km long transect, including 2–3 stations inside the river plume, one station on the visible turbidity front, and two stations outside the plume. Shipboard campaigns were conducted in January (summer), August (winter), and October 2003 (spring). On each occasion, conductivity–temperature–depth casts, bottom track acoustic Doppler current profiler current measurements, size-fractioned chlorophyll concentration, and stratified plankton sampling were conducted. A significantly higher abundance of barnacle nauplii was found at the river plume front than at the plume or outside the plume. Abundance was highest in the upper 10 m of the water column, where most nauplius larvae were found. The river plume appeared as a surface layer of less saline water moving north of the river mouth, with a buoyant frontal structure progressing at speeds of 5 to 20 cm s−1. Although no peak in chlorophyll was observed at the buoyant front, the highest concentration of effective prey size for feeding nauplii (chlorophyl-a <5 and 5–20 μm) was generally associated with less saline plume waters. Thus, the accumulation of barnacle larvae at the front may facilitate foraging, potentially increasing larval growth and energy reserves. Our results suggest that the spatial structure and temporal dynamics of river plumes should be considered by benthic ecologists as transport mechanisms that potentially affect larval delivery and settlement of barnacles on rocky shores.

The influence of circulation on abundance patterns of larval fish was compared at different phases of the tide in the vicinity of an estuarine front in Corral Bay, Chile during austral spring. Greatest differences in water salinity were found across the frontal region on ebb tides. Because rainfall was low, density differences were primarily due to tidal intrusion of salt water. Larval density was relatively low during both sampling periods with Strangomera bentincki, Oodntesthes regia laticlavia, Gobiesox marmoratus and Hypsoblennius sordidus as the most abundant species. Total ichthyoplankton was always higher near the tidal front (Stations 2 and 3). Spatial distribution in relation to tidal phase showed different patterns for the most abundant fish larval species. Circulation and larval distribution revealed that the bay was a source of young fish larvae but older individuals could also be recruited in and retained there. Results show that the front could act as a physical boundary for larvae transported from offshore through specific mechanism of circulation related with the tidal regime.