PREDICTING THE SPATIAL-DISTRIBUTION OF CLIMATE - TEMPERATURE IN GREAT-BRITAIN

1. The prediction and mapping of climate in areas between climate stations is of increasing importance in ecology.

2. Four categories of model, simple interpolation, thin plate splines, multiple linear regression and mixed spline-regression, were tested for their ability to predict the spatial distribution of temperature on the British mainland. The models were tested by external cross-verification.

3. The British distribution of mean daily temperature was predicted with the greatest accuracy by using a mixed model: a thin plate spline fitted to the surface of the country, after correction of the data by a selection from 16 independent topographical variables (such as altitude, distance from the sea, slope and topographic roughness), chosen by multiple regression from a digital terrain model (DTM) of the country.

4. The next most accurate method was a pure multiple regression model using the DTM. Both regression and thin plate spline models based on a few variables (latitude, longitude and altitude) only were comparatively unsatisfactory, but some rather simple methods of surface interpolation (such as bilinear interpolation after correction to sea level) gave moderately satisfactory results. Differences between the methods seemed to be dependent largely on their ability to model the effect of the sea on land temperatures.

5. Prediction of temperature by the best methods was greater than 95% accurate in all months of the year, as shown by the correlation between the predicted and actual values. The predicted temperatures were calculated at real altitudes, not subject to sea-level correction.

6. A minimum of just over 30 temperature recording stations would generate a satisfactory surface, provided the stations were well spaced.

7. Maps of mean daily temperature, using the best overall methods are provided; further important variables, such as continentality and length of growing season, were also mapped. Many of these are believed to be the first detailed representations at real altitude.

8. The interpolated monthly temperature surfaces are available on disk.

Holocene “turn-on” and evolution of the Southern Great Barrier Reef: Revisiting reef cores from the Capricorn Bunker Group

Extensive drilling of the Great Barrier Reef (GBR) in the 70s and 80s illuminated the main factors controlling reef growth during the Holocene. However, questions remain about: (1) the precise nature and timing of reef "turnon" or initiation, (2) whether consistent spatio-temporal patterns occur in the bio-sedimentologic response of the reef to Holocene sea-level rise then stability, and (3) how these factors are expressed in the context of the different evolutionary states (juvenile-mature-senile reefs). Combining 21 new C14-AMS and 146 existing recalibrated radiocarbon and U/Th ages, we investigated the detailed spatial and temporal variations in sedimentary facies and coralgal assemblages in fifteen cores across four reefs (Wreck, Fairfax, One Tree and Fitzroy) from the Southern GBR. Our newly defined facies and assemblages record distinct chronostratigraphic patterns in the cores, displaying both lateral zonation across the different reefs and shallowing upwards sequences, characterised by a transition from deep (Porites/faviids) to shallow (Acropora/Isopora) coral types. The revised reef accretion curves show a significant lag period, ranging from 0.7-2 ka, between flooding of the antecedent Pleistocene substrate and Holocene reef turn-on. This lag period and dominance of more environmentally tolerant early colonizers (e.g., domal Porites and faviids), suggests initial conditions that were unfavourable for coral growth. We contend that higher input of fine siliciclastic material from regional terrigenous sources, exposure to hydrodynamic forces and colonisation in deeper waters are the main factors influencing initially reduced growth and development. All four reefs record a time lag and we argue that the size and shape of the antecedent platform is most important in determining the duration between flooding and recolonisation of the Holocene reef. Finally, our study of Capricorn Bunker Group Holocene reefs suggests that the size and shape of the antecedent substrate has a greater impact on reef evolution and final evolutionary state (mature vs. senile), than substrate depth alone. 

The Cyrenaican Prehistory Project 2011: Late-Holocene environments and human activity from a cave fill in Cyrenaica, Libya

Little is known about late Holocene environmental change in Cyrenaica. The late Holocene sequence in the Haua Fteah, the key regional site, is highly discontinuous and characterised by stable-burning deposits. The geoarchaeology of the late-Holocene cave fill of a small cave, CP1565, located close to the Haua Fteah, is described. The well-stratified sequence, dating from the fourth century AD to the present day, provides a glimpse of life at the bottom of the settlement hierarchy and of changing environments over the last 1600 years, with degraded vegetation and aridity in the ‘Little Ice Age’.

Deglacial mesophotic reef demise on the Great Barrier Reef

Submerged reefs are important recorders of palaeo-environments and sea-level change, and provide a substrate for modern mesophotic (deep-water, light-dependent) coral communities. Mesophotic reefs are rarely, if ever, described from the fossil record and nothing is known of their long-term record on Great Barrier Reef (GBR). Sedimentological and palaeo-ecological analyses coupled with 67 14C AMS and U–Th radiometric dates from dredged coral, algae and bryozoan specimens, recovered from depths of 45 to 130 m, reveal two distinct generations of fossil mesophotic coral community development on the submerged shelf edge reefs of the GBR. They occurred from 13 to 10 ka and 8 ka to present. We identified eleven sedimentary facies representing both autochthonous (in situ) and allochthonous (detrital) genesis, and their palaeo-environmental settings have been interpreted based on their sedimentological characteristics, biological assemblages, and the distribution of similar modern biota within the dredges. Facies on the shelf edge represent deep sedimentary environments, primarily forereef slope and open platform settings in palaeo-water depths of 45–95 m. Two coral–algal assemblages and one non-coral encruster assemblage were identified: 1) Massive and tabular corals including Porites, Montipora and faviids associated with Lithophylloids and minor Mastophoroids, 2) platy and encrusting corals including Porites, Montipora and Pachyseris associated with melobesioids and Sporolithon, and 3) Melobesiods and Sporolithon with acervulinids (foraminifera) and bryozoans. Based on their modern occurrence on the GBR and Coral Sea and modern specimens collected in dredges, these are interpreted as representing palaeo-water depths of < 60 m, < 80–100 m and > 100 m respectively. The first mesophotic generation developed at modern depths of 85–130 m from 13 to 10.2 ka and exhibit a deepening succession of < 60 to > 100 m palaeo-water depth through time. The second generation developed at depths of 45–70 m on the shelf edge from 7.8 ka to present and exhibit stable environmental conditions through time. The apparent hiatus that interrupted the mesophotic coral communities coincided with the timing of modern reef initiation on the GBR as well as a wide-spread flux of siliciclastic sediments from the shelf to the basin. For the first time we have observed the response of mesophotic reef communities to millennial scale environmental perturbations, within the context of global sea-level rise and environmental changes.