Atmospheric acidification history of Loch Laidon: a comparison of pollution records from 1985 and 1995 sediment cores

Like many oligotrophic softwater lochs in Scotland, Loch Laidon has been acidified by atmospheric pollution (Flower et al. 1988). The process started in the 19th century when industrial emissions began to contribute acidity (as sulphur and nitrogen oxides), heavy metals, fly ash and other trace contaminants in significant quantities to the atmosphere. Acidification of many sensitive freshwater lochs typically proceeded throughout the 20th century ( e.g. Battarbee et al. 1988a). However, as a result of industrial decline and implementation of some source controls, UK total acid emissions declined by about a third between the mid- l 970s and the mid-1980s (Irwin et al. 1990). This change has been linked to small decreases in the measured acidities of some Scottish lochs during the late l 970s and 1980s (Harriman et al. 1996). Biological improvements over this period are less clear, although diatom communities in two upland lochs in Galloway (Battarbee et al. 1988b, Allott et al. 1992) do show minor floristic recoveries since ca. 1980. The time-scale and extent of acidification of Loch Laidon was revealed by microfossil and geochemical analysis of a radiometrically dated sediment core retrieved from the loch in 1985 (Flower et al. 1988). The most recent sediment in this core showed no evidence of any significant recovery trend in loch water acidity. Similarly, sediment contamination by spheroidal carbonaceous particles (SCPs), a fly ash component of high temperature fossil fuel burning, showed an increasing trend to the sediment surface (1985). To test if any biologically significant changes or any decline in atmospheric contamination (as defined by SCP analysis) of the loch had occurred in the 10 years subsequent to the 1985 palaeo-survey, re-sampling was carried out in 1995. This re-survey entailed collecting a sediment core from approximately the same location as the 1985 core and analysing it in similar ways. Changing pollutant deposition patterns and possible lag-effects in biological responses to the late 1970s acid emission decline, makes examination of the sediment record of the intervening 10 years of particular interest. This report presents results of radiometric dating, diatom analysis and SCP analysis of the 1995 sediment core. Using the time scale provided by sediment dating, diatom analysis is used to reconstruct recent trends in water pH and SCP analysis is used to identify recent trends in direct atmospheric contamination. By comparing the 1995 results with those obtained from the earlier core (Flower et al. 1988), not only is the post 1985 sediment record made available but also replicability of the methods for the pre- 1985 sediment sections is tested

Sediment accumulation in the Broads. A report to the Broads Authority

Sediment accumulation rate data are described for 15 cores from 11 sites in the Norfolk and Suffolk Broads. Sediment dating was determined using a combination of radiometric ({210}^Pb, {137}^Cs) and spheroidal carbonaceous particle techniques. These approaches were combined to produce a ‘best available chronology’ for each site. However, at some sites results were still poor and the resulting data must be treated with caution

Scaling of axial muscle architecture in juvenile Alligator mississippiensis reveals an enhanced performance capacity of accessory breathing mechanisms

Quantitative functional anatomy of amniote thoracic and abdominal regions is cru-cial to understanding constraints on and adaptations for facilitating simultaneous breathing and locomotion. Crocodilians have diverse locomotor modes and variable breathing mechanics facilitated by basal and derived (accessory) muscles. However, the inherent flexibility of these systems is not well studied, and the functional spe-cialisation of the crocodilian trunk is yet to be investigated. Increases in body size and trunk stiffness would be expected to cause a disproportionate increase in mus-cle force demands and therefore constrain the basal costal aspiration mechanism, necessitating changes in respiratory mechanics. Here, we describe the anatomy of the trunk muscles, their properties that determine muscle performance (mass, length and physiological cross- sectional area [PCSA]) and investigate their scaling in juvenile Alligator mississippiensis spanning an order of magnitude in body mass (359 g– 5.5 kg). Comparatively, the expiratory muscles (transversus abdominis, rectus abdominis, ili-ocostalis), which compress the trunk, have greater relative PCSA being specialised for greater force- generating capacity, while the inspiratory muscles (diaphragmaticus, truncocaudalis ischiotruncus, ischiopubis), which create negative internal pressure, have greater relative fascicle lengths, being adapted for greater working range and contrac-tion velocity. Fascicle lengths of the accessory diaphragmaticus scaled with positive allometry in the alligators examined, enhancing contractile capacity, in line with this muscle's ability to modulate both tidal volume and breathing frequency in response to energetic demand during terrestrial locomotion. The iliocostalis, an accessory expira-tory muscle, also demonstrated positive allometry in fascicle lengths and mass. All accessory muscles of the infrapubic abdominal wall demonstrated positive allometry in PCSA, which would enhance their force- generating capacity. Conversely, the basal tetrapod expiratory pump (transversus abdominis) scaled isometrically, which may in-dicate a decreased reliance on this muscle with ontogeny. Collectively, these find-ings would support existing anecdotal evidence that crocodilians shift their breathing mechanics as they increase in size. Furthermore, the functional specialisation of the diaphragmaticus and compliance of the body wall in the lumbar region against which it works may contribute to low- cost breathing in crocodilian

Acidification in the Cairngorms and Lochnagar: a palaeoecological assessment

Sensitive lakes in areas of the United Kingdom with moderate to high sulphur deposition have been acidified since the middle of the nineteenth century- (Battarbee et al. 1988). Regions such as Galloway, south west Scotland (eg. Flower and Battarbee 1983, Flower et al. 1987), Wales (eg. Battarbee et al. 1988, Fritz et aL 1990), Cumbria (eg. Battarbee et al 1988, Atkinson and Haworth 1990), and Rannoch Moor in the central Scottish Highlands (eg. Flower et al 1988) have been affected. This study extends the geographical survey of lake acidification to the Caimgorm and Lochnagar regions of north east Scotland (Figure 1). The Caimgorms and Lochnagar are areas of considerable conservation value, forming the largest single area of land over 1000 m in the UK. The Caimgorm mountain plateau is a National Nature Reserve, noted for its alpine flora and fauna, whilst the Lochnagar range is a Scottish Wildlife Trust reserve. A secondary- aim of the study was to evaluate the 11land-use 11 hypothesis (eg. Rosenqvist 1977, 1978, 1981) as a mechanism for lake acidification by examining high altitude sites with no active land-management. Sites selected are all remote, lie above the tree line and have undisturbed catchments. Lochnagar and the Caimgorms are situated on sensitive granite geology (Kinniburgh and Edmunds 1986, Wells et al. 1986) in an area of moderate acid deposition (c. 0.95 g S yr-1 ). It can be predicted that sensitive lakes in this area (those having Ca2 + values of <60 μeq i-1 ) will have acidified (Battarbee 1989)

Consequences of fish kills for long-term trophic structure in shallow lakes: implications for theory and restoration

Fish kills are a common occurrence in shallow, eutrophic lakes, but their ecological consequences, especially in the long-term, are poorly understood. We studied the decadal-scale response of two UK shallow lakes to fish kills using a palaeolimnological approach. Eutrophic and turbid Barningham Lake experienced two fish kills in the early 1950s and late 1970s with fish recovering after both events, whereas less eutrophic, macrophyte-dominated Wolterton Lake experienced one kill event in the early 1970s from which fish failed to recover. Our palaeo-data show fish-driven trophic cascade effects across all trophic levels (covering benthic and pelagic species) in both lakes regardless of pre-kill macrophyte coverage and trophic status. In turbid Barningham Lake, similar to long-term studies of biomanipulations in other eutrophic lakes, effects at the macrophyte-level are shown to be temporary after the first kill (c.20 years) and non-existent after the second kill. In plant-dominated Wolterton Lake permanent fish disappearance failed to halt a long-term pattern of macrophyte community change (e.g. loss of charophytes and over-wintering macrophyte species) symptomatic of eutrophication. Important implications for theory and restoration ecology arise from our study. Firstly, our data support ideas of slow eutrophication-driven change in shallow lakes where perturbations are not necessary prerequisites for macrophyte loss. Secondly, the study emphasises a key need for lake managers to reduce external nutrient-loading if sustainable and long-term lake restoration is to be achieved. Our research highlights the enormous potential of multi-indicator palaeolimnology and alludes to an important need to consider potential fish kill signatures when interpreting results

Palaeoecological study of Rockland Broad

The decline in ecological quality and conservation value of European fresh waters is an all too common phenomenon. In lowland Britain the main anthropogenic impact on aquatic systems is that associated with elevated nutrient loading. The Broads are internationally important wetlands spanning a number of river basins in East Anglia. The Broads have suffered, along with other wetlands, and it is chiefly eutrophication that has had a deleterious effect on the system (Mason & Bryant 1975, Moss 1977) with a resultant decline in their ecological quality and conservation value. One of the changes in the ecological structure and functioning of shallow lakes in response to enrichment is an alteration in their macrophyte flora (Ris & Sand-Jensen 2001) and in extreme cases there may be the complete loss of submerged plants (Scheffer et al. 1993). The loss of the diversity of the macrophyte flora in the Broads is perhaps the main factor in the decline in their conservation value

Environmental change and atmospheric contamination across China as indicated by lake sediments (Joint Project Q741)

In China, anthropogenic impact from changes in water quality, land-use and atmospheric deposition vary both spatially and temporally. There is a gradient across the country from the populous lowlands in the east, where considerable long-term impact on water bodies has resulted from centuries of agricultural and aquacultural practices superimposed by more recent, rapid industrial growth; to the mountainous west where many areas remain minimally impacted and any anthropogenic impact is restricted to long-range transport of atmospheric pollutants and change in climate. Currently, however, there is little information on temporal trends in atmospheric deposition. The importance of water resources in China cannot be overestimated and therefore determining the extent, rate and direction of change in water quality is a national priority. In the absence of long-term monitoring programmes, lake sediments remain the only way whereby this information can be retrospectively determined at the necessary temporal scale to ascertain whether the causes of any detriment in quality are as a result of natural changes, or due to agricultural or industrial impacts. Therefore, the aim of this research programme is to use lake sediments from three regions of China to detennine the extent to which impacts to lakes have changed through time and the causes of these changes. The project focuses on an east - west transect along the Yangtse River. The Middle and Lower Reaches of the Yangtse are undergoing exceptionally rapid economic and industrial development and this region is receiving a great deal of attention as the Three Gorges Dam undergoes construction. The three areas in which lakes are to be studied in this proposal are: l. Jiangsu Province in east China north of Shanghai. Lowland sites. Lakes in this area are likely to have been impacted by long-term agriculture and may therefore may have become eutrophic. Atmospheric deposition may also be significant from local and regional industrial sources. 2. The upper reaches of the Yangtse River, in Sichuan and Yunnan Provinces. Lakes at l-2000m. Lakes in this area may have been impacted by agriculture, but where possible sites will be selected where direct impact is minimal. Lakes may therefore be mesotrophic but sources of atmospherically derived industrial pollutants are likely to be remote. 3. The Tibetan Plateau. Lakes at 4 - 5000m. 'Control' sites in a pristine area with minimal human influence. Sediment cores from these sites will be used to detem1ine background levels of atmospherically deposited contaminants. Oligotrophic (low nutrient) sites on sensitive geology (low acid neutralising capacity e.g. granites) will be selected where possible. By including earlier collaborative work between the participating institutes (funded by the Royal Society and the Chinese Academy of Sciences) on the lake sediment records on the Jianghan Plain and research currently being undertaken on lakes in the Shennonggjia region in western Hubei (NNFSC funded), this study will produce a transect of lakes from five regions providing a unique database on the historical impact of human activity on the freshwater environment