Some life-history parameters of the non-native amphipod Platorchestia platensis (Talitridae) in a warm temperate South African estuary

Density, population structure, growth, mortality and aspects of reproduction of the non-native amphipod Platorchestia platensis were studied for 20 consecutive months (October 2008 to May 2010) in the supralittoral wrack of the Knysna Estuary, South Africa. Amphipod density varied over the sampling period with the lowest numbers recorded in summer (January and February). Ovigerous females with embryos, and juveniles were found in most months with peaks in recruitment found in both April and October, suggesting that in Knysna this species is a biannual breeder. Average female size was significantly greater in winter, with larger females tending to brood more embryos. The largest adults (13.5 mm total length) were always male although the monthly sex ratio was nearly always female biased. Growth rate estimated from a cohort analysis was about 1 mm per month and monthly survival about 69%. The ability to reproduce all year round may be one reason why this introduced species has become established within this warm temperate estuary

Morpho-acoustic Characterization of Natural Seepage Features near the Macondo Wellhead (ECOGIG Site OC26, Gulf of Mexico)

OC26 (R/V Oceanus Site 26) is one of three primary sites selected for study by the Ecosystem Impact of Oil and Gas Inputs to the Gulf (ECOGIG) consortium to determine the impacts of natural seepage versus large pulse inputs of hydrocarbons into the Gulf of Mexico (GOM) and to chart the long-term effects and mechanisms of ecosystem recovery from the Deep Water Horizon Oil Spill in 2010. OC26 is located on the western slope of the Gloria Dome, about five kilometers south-east of the Macondo wellhead. In 2011, the site was visited by the NOAA research vessel Okeanos Explorer. During this cruise, several natural oil/gas plumes originating from the seabed were identified. In order to establish precise locations for these naturally occurring sources of hydrocarbons and to inform biogeochemical and biological studies of the water-column, the seafloor, and the shallow subseafloor in the wake of the Deep Water Horizon spill, we conducted several Autonomous Underwater Vehicle (AUV) surveys. The surveys were designed to include swath bathymetry, chirp sub-bottom profiles, and seafloor still photos to augment the Okeanos Explorer and the 2012 ECOGIG Falkor multibeam bathymetric and water column data. These AUV high resolution datasets were collected to provide in-depth geophysical analyses of seafloor morphology and to link, where possible, morphological features to the subsurface structure and plumbing system at this site where natural seepage possibly intersects hydrocarbon inputs from the spill. The site exhibits many morphological seafloor features: depressions, elongated erosional structures, dome-shaped mud volcanoes/mounds, fault traces, and round pockmarks. Seabed photos show the presence of gas hydrate outcrops and benthic communities in the vicinity of maximum seafloor backscatter intensities and many of the morphological features. Subsurface profiles show gas-related anomalies (blanking and acoustic wipeout) where pockmarks, mud volcanoes/mounds and depressions are located. In addition to the discovery of novel seafloor features, these studies provide definitive links between seafloor seeps and particular morphologies and communities, contributing to the fundamental understanding of seeps in the deep sea. (C) 2016 Published by Elsevier Ltd

A novel mutation in the cystic fibrosis gene in patients with pulmonary disease but normal sweat chloride concentrations

Many patients with chronic pulmonary disease similar to that seen in cystic fibrosis have normal (or nondiagnostic) sweat chloride values. It has been difficult to make the diagnosis of cystic fibrosis in these patients because no associated mutation in the cystic fibrosis transmembrane conductance regulator (CFTR) gene has been identified. We evaluated 23 patients with pulmonary disease characteristic of cystic fibrosis but with sweat chloride concentrations in the normal range. Mutations in the CFTR gene were sought by direct sequencing of polymerase chain reaction-amplified nasal epithelial messenger RNA and by testing the functioning of affected epithelium. A cytidine phosphate guanosine dinucleotide C-to-T point mutation in intron 19 of the CFTR gene, termed 3849+10 kb C to T, was identified in 13 patients from eight unrelated families. This mutation was found in patients from three different ethnic groups with three different extended haplotypes. The mutation leads to the creation of a partially active splice site in intron 19 and to the insertion into most CFTR transcripts of a new 84-base-pair “exon,” containing an in-frame stop codon, between exons 19 and 20. Normally spliced transcripts were also detected at a level approximately 8 percent of that found in normal subjects. This mutation is associated with abnormal nasal epithelial and sweat acinar epithelial function. We have identified a point mutation in intron 19 of CFTR and abnormal epithelial function in patients who have cystic fibrosis-like lung disease but normal sweat chloride values. The identification of this mutation indicates that this syndrome is a form of cystic fibrosis. Screening for the mutation should prove diagnostically useful in this population of patients

Comparing production-biomass ratios of benthos and suprabenthos in macrofaunal marine crustaceans

Using available data from the literature, we compared the productionbiomass ratios (P/B) between the suprabenthic (= hyperbenthic) and the benthic (infaunaepifauna) species within the group of the macrofaunal marine crustaceans. This data set consists of 91 P/B estimates (26 for suprabenthos and 65 for infaunaepifauna) for 49 different species. Suprabenthic crustacean P/B was significantly higher than P/B of benthic crustacean (post-hoc Scheffé test; one-way analysis of covariance, ANCOVA; p < 103) and also of other (noncrustacean) benthic invertebrate (p < 104). Predictive multilinear regression (MLR) analysis for macrofaunal marine crustaceans showed P/B to depend significantly on mean annual temperature (T) and mean individual weight (W) (R2 = 0.367). Adding the variable swimming capacity increased goodness-of-fit to R2 = 0.528. The higher P/B of suprabenthic (= swimming) macrofauna in comparison with that of the benthic compartment seems to be related to the most apparent feature of the suprabenthos, its swimming capacity. The high P/Bs reported for suprabenthic species indicate how a nontrivial part of benthic production can be ignored if suprabenthos is not well sampled, therefore biasing the models of energy flow generated for trophic webs

Causes and consequences of marine mammal population declines in southwest Alaska: a food-web perspective

Populations of sea otters, seals and sea lions have collapsed across much of southwest Alaska over the past several decades. The sea otter decline set off a trophic cascade in which the coastal marine ecosystem underwent a phase shift from kelp forests to deforested sea urchin barrens. This interaction in turn affected the distribution, abundance and productivity of numerous other species. Ecological consequences of the pinniped declines are largely unknown. Increased predation by transient (marine mammal-eating) killer whales probably caused the sea otter declines and may have caused the pinniped declines as well. Springer et al. proposed that killer whales, which purportedly fed extensively on great whales, expanded their diets to include a higher percentage of sea otters and pinnipeds following a sharp reduction in great whale numbers from post World War II industrial whaling. Critics of this hypothesis claim that great whales are not now and probably never were an important nutritional resource for killer whales. We used demographic/energetic analyses to evaluate whether or not a predator–prey system involving killer whales and the smaller marine mammals would be sustainable without some nutritional contribution from the great whales. Our results indicate that while such a system is possible, it could only exist under a narrow range of extreme conditions and is therefore highly unlikely