Mid‐Holocene Development of Mangrove Communities Featuring Rhizophoraceae and Geomorphic Change in the Richmond River Estuary,New South Wales,Australia

This paper describes the hitherto unreported occurrence of mid‐Holocene mangrove deposits in the Richmond River estuary, southeastern Australia, thereby providing evidence for changes in the distribution and composition of mangrove communities within a subtropical estuarine system during the Holocene. Stratigraphic, radiocarbon and palynological evidence indicates that widespread development of mangrove communities took place in the upstream reaches of the Richmond River estuary during the period 7000 to 6000 years BP. These communities maintained their habitat through substrate aggradation under the conditions of a moderate sea‐level rise, in contrast to other estuaries within the region, which generally experienced the submergence of intertidal substrates. Mangrove species belonging to the family Rhizophoraceae, most likely Bruguiera gymnorrhiza and Rhizophora stylosa, dominated these communities, in strong contrast to contemporary communities, which are dominated by Avicennia marina. Moreover, these mid‐Holocene communities were located a considerable distance upstream of the contemporary occurrences of Rhizophoraceae species within the estuary. The changes in the spatial distribution and composition of mangrove communities parallel the large‐scale evolution of the estuary driven by sea‐level variation. Shallow, buried Pleistocene terraces probably contributed to the regionally unique aggradational response of the mangrove communities and their substrates to a sea‐level rise during mid‐Holocene times.     

On the Possible Origins of an Unusual (Mid to Late Holocene) Coastal Deposit,Old Punt Bay,South‐East Australia

An unusual coarse, shelly sedimentary unit is found elevated above present mean sea level in a sheltered pocket embayment at Old Punt Bay in south‐eastern Australia. The coarse sediments, diverse microfauna, and large shelly macrofauna of mixed affinity suggest that the deposit is the result of high‐energy deposition. The deposit was previously thought to have been deposited 1000–1300 cal bp based on one shell dated using ¹⁴C and amino acid racemisation. However, additional ¹⁴C dating indicates a likely age of ～2500 cal bp . Regardless of age constraints, the presence of rock‐encrusting oyster shells and large articulated bivalves, suggests that the depositional event must have been capable of removing and transporting coarse sediments (rock clasts), bivalves, and oysters shells from a variety of seaward environments and depositing them with little abrasion, something storm waves are unlikely to do. The deposit may be tsunamigenic. If a tsunami origin is accepted, the new dating results indicate that it is possibly coeval with a tsunami event previously reported to have affected several other sites along the coast of New South Wales at c. 2900 cal bp . Consequently, this deposit provides evidence for the event at a new site and importantly, a tighter constraint on the likely date of the events occurrence. It further adds weight to the developing catalogue of palaeotsunamis that may have affected the south‐eastern coast of Australia. Regardless of the deposit's origins, if viewed from a coastal planning perspective, this deposit indicates that this part of the coast has experienced large‐scale overwash events in the past that if repeated, would be catastrophic. There are serious implications for risk management.     

Historical signature of Roman mining activities in the Bidasoa estuary (Basque Country,northern Spain): an integrated micropalaeontological,geochemical and archaeological approach

This work presents an integrated micropalaeontological (foraminiferal content), geochemical (Pb, Zn, Cu, Ni, Cr, and Al, Pb isotope ratios, radiocarbon dating) and archaeological approach to the environmental impact caused by Roman mining in the Bidasoa estuary (northern Spain). Sediments collected in the ancient Roman port of Irun represent a typical infilling sequence, reflecting a progressive isolation from the estuarine environment. They exhibit elevated contents of Pb, clearly higher than those recommended nowadays for acceptable sediment quality. Isotope composition confirms exploitation of local galenas as the main source for this metal. Results from a borehole (25 m long) reveal that Pb pollution extended also to the adjacent estuarine area. The beginning of Roman mining activities is recorded by a marked increase in Pb concentrations. However, the maximum value appears later in time (after 660 cal AD). Although this enrichment could be related to the reworking upstreams of previously polluted materials, recently obtained archaeological data suggest that episodes of historically non-documented mining activities could have taken place in the surrounding area after Roman times.     

钱塘江河口涌潮强弱的历史变迁(1471-2001)

整理《中国近五百年旱涝分布图集》及其"续编""再续编"中1471-2000年间浙江金华与安徽屯溪两个站点的旱涝指数,将其作为反映钱塘江年径流量波动的指标,根据1950-2000年实测的钱塘江径流大小与海宁盐官站潮差和涌潮大小的相关关系,推断出五百余年来钱塘江涌潮强度变迁趋势。经检验,钱塘江流域旱涝指数特征与史料所载涌潮异常年份相符,且指数序列与同时期海宁盐官历年最大潮差值序列之间的相关系数具有较强相关性。将现代实测盐官历年最大潮差与旱涝指数拟合,得到函数关系式为y=-7.2x2+40.3x+580.1(其中x为旱涝指数,y为盐官年最大潮差)。又根据盐官潮差与涌潮高度间函数关系推出了明中期以后盐官历年涌潮最大强度,并绘制了1471-2001年间的钱塘江涌潮强弱变化曲线图。     

The Evolution of a Holocene Estuarine Barrier on the Coromandel Coast,New Zealand

Whitianga Harbour on the Coromandel Peninsula, North Island, New Zealand is fronted by a broad sandy barrier composed of linear beach ridges. The barrier developed through a process of rollover as sea level rose in the early Holocene with shelly sandy sediment washed inland over estuarine muds. These overwash deposits are present to 3 m below sea level in the back barrier area. Once sea level stabilised and barrier rollover had ceased the barrier continued to prograde in a series of beach ridges. The back barrier area is characterised by estuarine muds, overlain by splay and overwash deposits that are reworked by fluvial and tidal channels. The initial flooding of the estuary occurred at around 7350–7225 years cal BP, reaching modern levels by 6894–6729 years cal BP at the earliest. Infill was rapid as evidenced by estuarine species (crustaceans and bivalves) preserved in life position. From ～6000 years BP to present, the estuary is characterised by tidal and fluvial reworking, suggesting that modern sediment inputs are bypassing the estuary.     

Stable isotope reconstructions of shellfish harvesting seasonality in an estuarine environment: implications for Late Holocene San Francisco Bay settlement patterns

Seasonality estimates based on stable isotope analyses of shellfish remains has been an important thrust of settlement pattern reconstruction, allowing researchers to place people on the landscape at points in space at different times of the year. In exposed coastal settings seasonality reconstructions are typically dependent on annual changes in water temperature. This paper has two goals. First, we continue development of a method for determining shellfish harvest seasonality in estuarine environments where annual salinity changes, not temperature, drive isotopic variation. Second, we contribute to settlement pattern studies by showing how small and large sites can be linked into a single system by examining different site types and shellfish species. Our case study focuses on the Late Prehistoric period of the San Francisco Peninsula, includes a large shellmound (CA-SMA-6) and an ephemeral camp (CA-SFR-171), and examines clam (Macoma spp.) and mussel (Mytilus spp.) harvesting. In this case, data support a fission-fusion settlement pattern, with periods of dispersal during late winter through early summer and aggregation in late summer through early winter.     

Effectiveness of Local Biodiversity Action Plans to Identify Locally Rare and Endangered Fish in Scotland

Biodiversity loss is an important environmental issue globally. Local Biodiversity Action Plans (LBAPs) provide an important conservation tool and should represent national priority species where they are present. Although much effort has gone in to developing LBAPs, their value as a conservation tool has been questioned. Here the effectiveness of the LBAP system to raise awareness of the freshwater fishes of national and international priority in Scotland is tested. Inclusion of freshwater fish in the LBAP suite was evaluated using current distribution data taken from available literature sources. Of the 25 examined LBAPs in Scotland, there were 79 LBAP entries for the 12 priority freshwater fishes found in Scotland. This contrasts with an expectation of 139 entries. Nineteen authorities failed to represent all priority freshwater fish species extant in their geographical boundary. Fourteen authorities provided cover for 50% or less for the species distributed in their area and five authorities included no rare freshwater fish species where one or more was expected. Possible underlying reasons for this mismatch include: frequently changing conservation status and taxonomic blindness of this group. It is plausible to suggest that this low rate of inclusion will have a detrimental effect on the allocation of limited conservation resources.     

The study of collector variability in the transition to sedentary food producers in northern Colombia

Human adaptation to the tropics by populations of collectors has been a longtanding issue of debate, especially with regard to the role that collectors may have played in pathways toward sedentism and food production. In this essay, I examine significant differences in strategies developed for estuarine environments versus the inland environments of the transitional savannas of northern Colombia to analyze how these two adaptations articulate with the processes which led toward sedentism and food production in neotropical northern Colombia. Contrary to the received wisdom, I argue that the exploitation of rich estuarine environments is not necessarily a prelude to food production; seed exploitation early in the sixth millennium B.P. in the northern Colombian transitional savanna zone provides a second and arguably more probable model.     

The Palaeo‐Environmental Contexts of Three Possible Phoenician Anchorages in Portugal

The 2002 Joint Expedition of the Institute of Nautical Archaeology and the Centro Nacional de Arqueologia Náutica e Subaquática examined Phoenician maritime involvement in Portugal, combining archaeological, geological and geophysical surveys of former coastal sites—Santa Olaia, Abul and Castro Marim—where previous excavations have uncovered Phoenician remains. Significant geomorphic evolution of bay‐head delta and estuarine settings masks the fact that Phoenician sites were situated at the head of marine embayments or on estuary margins, had easy access to the sea, and immediate access to at least one natural anchorage. All sites exhibited topographical criteria familiar from Phoenician trading‐stations and merchant outposts in the Mediterranean. © 2009 The Authors