Source characterisation and mid-term spatial and temporal distribution of polycyclic aromatic hydrocarbons in molluscs along the Basque coast (northern Spain)

The variability of polycyclic aromatic hydrocarbons (PAH) measured in the soft tissues of Mediterranean mussels (Mytilus galloprovincialis) and Pacific oysters (Crassostrea gigas) are investigated. Samples were collected from estuarine waters within the Basque Country (Bay of Biscay), between 2003 and 2011. PAH bioaccumulation showed some seasonality and significant differences were observed between cold (autumn–winter) and warm (spring–summer) seasons. Sites located within the ports of Bilbao and Pasaia showed the highest PAH concentrations in molluscs, and the highest percentages of samples above the established Environmental Quality Standards and Environmental Assessment Criteria. Probably due to human activities carried out in the area, no clear trends were observed, between 2003 and 2011, for the autumn data. Since the Basque coast is an area with high population density and industrial activity, the congener profiles (which reveal the predominance of tetra-aromatics) and the diagnostic ratios identified urban/industrial combustion processes as the main PAH sources. However, natural and petrogenic sources cannot be disregarded.     

Growth and production of the red alga Gelidium sesquipedale off the Basque coast (northern Spain)

Several aspects of the growth of the agarophyte Gelidium sesquipedale Clemente (Thuret) were studied in sublittoral populations of the Basque coast (northern Spain) from 1981 to 1986. The standing stock of the populations varied greatly with season. During two consecutive years, 60 to 70% of summer biomass had been lost by the end of the unfavourable period of year to growth (autumn and winter). The decline in biomass was mainly due to partial losses of branches, with more branches being lost from larger fronds. Yearly variations in the standing stock were also recorded. Production estimates obtained by a destructive sampling method were not satisfactory because of the spatial heterogeneity of the populations at the three locations studied. Indirect estimation of production by measuring the growth of marked fronds in a control quadrat gave more reliable estimates. Production values of 622±124, 735±147 and 615±123 g dry wt m^-2 yr^-1 were obtained at the three locations, respectively. Frond elongation rates of 7.5, 6.1, 7.5 and 7.9 cm yr^-1, respectively, were recorded during four consecutive years. In winter elongation rates of fronds were rather low. Elongation did not seem to be affected by frond length, the self-shading effect of the canopy, or changes in depth. Cuts resulting from grazing were frequent on fronds through the year, decreasing significantly with increasing depth. Sheared fronds regenerated promptly, independent of season or height at which the cut was made. For commercial purposes the best season for harvesting is summer, which is the period of maximum standing stock, infertility, and calm warm waters that provide easier working conditions for divers.     

Monitoring morphological changes along the coast of Huelva (SW Spain) using soft-copy photogrammetry and GIS

This contribution deals with the use of different sources of data (field surveys with total station and GPS, air photographs and topographic maps) as well as their integrated digital treatment in a GIS context to quantify the morphological changes in a ridge of coastal dunes in the southwest of Spain. The results show very high and increm enting rates of foredune retreat significant losses of foredune surface and a clear negative sedimentary balance (lowering and inland migration) in its recent evolution (1979–1996). Two processes can explain this evolution: (1) marine erosion and (2) the reactivation of aeolian deflation. The combined use of GPS (code/phase) and soft-copy photogrammetry seem to provide the best for monitoring future changes.     

The development of aquaculture on the northern coast of Manila Bay (Philippines): an analysis of long-term land-use changes and their causes

This study documents the event chronology and causes of land-use change in a deltaic region of the Philippines since the beginnings of aquaculture in the late nineteenth century. Satellite images and topographic maps spanning the period 1972–2013 were processed to map fishponds and the natural habitats over which they have encroached. Historical archives were consulted and interviews were conducted to understand the historical exploitation of local natural resources and the reasons behind the recorded land changes. Results showed that aquaculture developed in the late nineteenth century and expanded subsequently across the landscape under a succession of forcing factors. The global market, for example, played an early role but a number of land-use changes were also a direct response to changing environmental constraints and natural hazards. These cumulative events have promoted continuous gain in favor of aquaculture, to the detriment of other land-use options.     

High relatedness and inbreeding in two species of haplodiploid eusocial thrips (Insecta: Thysanoptera) revealed by microsatellite analysis

Relatedness and inbreeding coefficients were estimated for Oncothrips tepperi and O. habrus, two species of eusocial gall-forming thrips, using data from two microsatellite loci. Relatedness between sets of individuals (sexes and castes) for O. tepperi ranged from 0.5 to 0.85 and for O. habrus estimates were centered around 0.5. Multiple mating in O. habrus was implicated in lowering relatedness within a gall. We estimated the inbreeding coefficient to be 0.38 for both species, the highest estimates known for eusocial insects. Our findings imply that high relatedness and inbreeding are important for the evolution and form of social behavior in Australian gall-forming Thysanoptera. Received: 14 November 1997 / Accepted after revision: 14 March 1998     

Toxicity of endosulfan on growth,photosynthesis, and nitrogenase activity in two species of Nostoc (Nostoc muscorum and Nostoc calcicola)

Treatments of the cyanobacteria Nostoc muscorum and Nostoc calcicola with the insecticide endosulfan (5, 10, and 20?µg?mL^?1) inhibited growth, photosynthetic pigments, photosynthetic, and nitrogenase activities. The sensitivity of N. muscorum to endosulfan was higher than that of N. calcicola. The toxic effect of endosulfan was more pronounced on phycocyanin; however, a considerable reduction in chlorophyll a and carotenoids was also noticed. ¹⁴C-fixation appeared to be more sensitive to the insecticide than photosynthetic oxygen evolution. Endosulfan caused strong inhibition of photosystem (PS) II activity whereas PS I was least affected. The inhibition of PS II activity was partially restored by electron donors (DPC, NH₂OH, and MnCl₂) at low dose of endosulfan. Nitrogenase activity was significantly suppressed in both species by the endosulfan at high dose (20?µg?mL^?1). On the basis of our comparative analysis, N. calcicola was found to be endosulfan resistant and can be used in paddy fields for better productivity under pesticide stress.     

Observations on metal concentrations in commercial landings of two species of tilapia (Oreochromis mossambicus and Oreochromis niloticus) from reservoirs in six river basins in Sri Lanka

Samples of the muscle of two species of tilapia (Oreochromis mossambicus and O. niloticus; 17–20 cm length) were obtained from at least one reservoir in each of the six river basins (Aruvi Aru, Kala Oya, Kirindi Oya, Ma Oya, Mahaweli, and Walawe Ganga catchments) in Sri Lanka. The metals Ca, Cu, Fe, K, Mg, Mn, Na, and Zn were consistently detected in the muscle tissue. Overall, there were few differences in the concentration of metals between the two species of fish, although there were also some statistically significant differences (p < 0.05) in the concentrations of some metals in fish obtained from some of the reservoirs. Aruvi Aru stands out as a river basin in which the two fish species have significantly lower concentration of metals when compared to other river basins. The concentration of the metals studied were below WHO and FSANZ guideline values for fish, suggesting that the consumption of the metals found in tilapia from these reservoirs poses little risk to human health.     

Proclivity and effectiveness in gall defence by soldiers in five species of gall-inducing thrips: benefits of morphological caste dimorphism in two species (<Emphasis Type="Italic">Kladothrips intermedius</Emphasis> and<Emphasis Type="Italic"> K. habrus</Emphasis>)

The essence of eusociality is a trade-off between producing ones own offspring and helping collateral kin via such activities as defence, foraging and brood rearing. This trade-off often involves morphological differences between helper and reproductive castes, but the advantages, correlates and phylogenetic context of morphological caste differentiation have seldom been analysed. Six species of Australian gall-inducing thrips on Acacia show morphological polymorphism. One morph, referred to as a soldier, has reduced wings and antennae but greatly enlarged fore-femora, which are thought to be adaptations for gall defence. The other, dispersing morph, has fully developed wings and relatively slight fore-femora. Here, we quantify the defensive behaviour of soldier morphs, and compare soldier and foundresses, using behavioural assays designed to measure proclivity to attack kleptoparasites (specialised invaders in the genus Koptothrips) and effectiveness in killing them. In all five species investigated, soldiers were able to kill Koptothrips. Moreover, the effectiveness of soldiers was relatively high in the more-derived species in the phylogeny of the clade, Kladothrips intermedius, K. habrus and K. waterhousei. Soldiers of K. intermedius and K. habrus also killed kleptoparasites more effectively than did foundresses, and K. habrus soldiers exhibited higher proclivity to attack than did foundresses. Data from naturally invaded galls demonstrate that soldiers in the field do kill Koptothrips, and vice versa. These results show that soldiers of Australian gall thrips are motivated and effective for gall defence.Communicated by D. Gwynne     

Impact of drought on the ecological and chemical status of surface water and on the content of arsenic and fluoride pollutants of groundwater in the province of Salamanca (Western Spain)

The impact of drought on the ecological and chemical status of surface and groundwaters of the River Tormes (River Duero basin, northwestern Iberian Peninsula) was studied to evaluate the evolution of the quality of the river during its passage through the city of Salamanca (Spain). The Water Quality Index (WQI) of the river revealed that the drought period of 2005 did not significantly affect water chemical quality. However, during the study period differences were found in surface water ecological quality, using phytoplankton quality as AN indicator. These differences may be accentuated as a result of regulation of the River Tormes by the Santa Teresa reservoir. Arsenic and fluoride concentrations were measured in water wells, finding higher arsenic concentrations after the drought period and no correlation between the arsenic and fluoride contents. The results are useful for an overall understanding of potential impact of climate change on the ecological and chemical status of water in regional systems.     

Bioaccumulation of platinum group metals on some fish species ( Oreochromis niloticus,Penaeus laspisulcates,Scylla serrate,Galaxias brevipinnis and Mollusc ) in the Pra estuary of Ghana

Catalytic converters have been designed to solve the problem of pollution from automobiles. However, recent studies have shown that the platinum group metals (PGMs) that are used in the design are being deposited alongside highways. The objective of this study was to measure the levels of PGMs that bioaccumulate in Oreochromis niloticus, Penaeus laspisulcates, Scylla serrate, Galaxias brevipinnis and Mollusc in the river Pra estuary along a major highway in Ghana. Chemical analysis using neutron activation analysis showed accumulation of the PGMs in all the biota species analysed. The S. serrate and mollusc showed higher accumulation than the other species. The mollusc and the other fish species in the estuary are consumed in Ghana, and therefore there is the need to educate the population on the effect of the PGMs on their health.     

Laboratory studies on the accumulation of inorganic mercury and methylmercury by the mussel (Mytilus galloprovincialis Lam) in relation to the presence of sediment

A comparative study on the accumulation of inorganic mercury and methylmercury by the mussel Mytilus galloprovincialis was based on nine days of exposure to 25 µg L^?1 HgCl₂ or to 2.5 µg L^?1 methylmercury in laboratory microcosms. Mercury (Hg) content was evaluated in the gills, digestive gland, and mantle. A higher accumulation occurred in the gills than in other tissues. The effect of the sediment on the bioaccumulation of the Hg species was evaluated. The results showed that the sediment accumulated the inorganic Hg more efficiently than the methylmercury. In both cases, the bioaccumulation in the tissues was reduced. The observed differences emphasized the need for caution when field results are compared with the results of laboratory experiments. The fate of either inorganic or organic Hg was depicted considering the absolute total amount given and the amount found in all the matrices (organism, sediment, and seawater).