Seawater acidification by CO2 in a coastal lagoon environment: Effects on life history traits of juvenile mussels Mytilus galloprovincialis

The carbonate chemistry of seawater from the Ria Formosa lagoon was experimentally manipulated, by diffusing pure CO2, to attain two reduced pH levels, by -0.3 and -0.6 pH units, relative to unmanipulated seawater. After 84 days of exposure, no differences were detected in terms of growth (somatic or shell) or mortality of juvenile mussels Mytilus galloprovincialis. The naturally elevated total alkalinity of the seawater (= 3550 µmol/kg) prevented under-saturation of CaCO3, even under pCO2 values exceeding 4000 µatm, attenuating the detrimental effects on the carbonate supply-side. Even so, variations in shell weight showed that net calcification was reduced under elevated CO2 and reduced pH, although the magnitude and significance of this effect varied among size-classes. Most of the loss of shell material probably occurred as post-deposition dissolution in the internal aragonitic nacre layer. Our results show that, even when reared under extreme levels of CO2-induced acidification, juvenile M. galloprovincialis can continue to calcify and grow in this coastal lagoon environment. The complex responses of bivalves to ocean acidification suggest a large degree of interspecific and intraspecific variability in their sensitivity to this type of perturbation. Further research is needed to assess the generality of these patterns and to disentangle the relative contributions of acclimation to local variations in seawater chemistry and genetic adaptation.

(Table1) Living and dead benthic foraminifera abundance in sediments of the Bottsand-Lagoon, Western Baltic Sea

Seasonal collections were made from 3 stations in a brackish lagoon near Kiel/Germany from December 1964 to June 1967. In addition 120 samples were taken in June 1966 to investigate the general pattern of distribution. Two species of the offshore fauna were found to dominate the lagoon (high population densities): Cribrononion articulatum and Miliammina fusca. The 'Vegetation zone' of the lagoon contains an assemblage of seven euryhaline arenaceous species. All of them were previously recorded from different regions of the world. - C. articulatum seems to prefer shallow water with a high daily range of water temperature (up to 30° Cels.). Population density and distribution show considerable differences between the different years. Size distribution curves of C. articulatum indicate main reproduction activity in spring and subsequent growth in uniform populations. Growth is terminated after six months but most of the specimens will either die in winter or reproduce the next spring; only a smaller amount is reproducing in summer or autumn. - Annual differences of the observed degree make it difficult to calculate foraminiferal productivity in a lagoonal environment and require seasonal observation over a period of at least 3 or 4 years.

(Table 1) Pollen analysis of peat horizons obtained from sediment cores of Beveroe-lagoon, Outer Flensburg Fjord

Pollen analytical studies were carried out on two sediment cores from Outer Flensburg Fjord taken by N. Exon (1972). 1) Based on the occurrence of Fagopyrum, the lower peat horizon (ca. 40 cm below mean sea level) of the inner lagoon near Beveroe developed after 1400 AD. The dominance of Pinus indicates that its formation may have taken place as late as the end of the 17th. Century. 2) Core No. 10872 from a water depth of 26.5 m contains the pollen zones VIII through the beginning of XI (Overbeck, 1950). Although salinity maxima fall in zone IX, they are not reflected in the pollen curves which show the normal picture found in South Jütland.

Seawater carbonate chemistry and calcification during a tropical lagoon study at SW lagoon, New Caledonia, 1991

A selective chemical photosynthesis inhibitor, DCMU (Dichorophenyl-dimethylurea), dissolved in DMSO (Dimethyl sulfoxide) was substituted for the dark incubation method commonly used to measure the oxygen consumption in metabolic and primary production studies. We compared oxygen fluxes during light incubations with DCMU and dark incubations procedure, on soft bottom benthos. For this purpose, we studied the effects of different DCMU concentrations. A concentration of 5 · 10-5 mol l-1 inside a clear incubation enclosure completely inhibits photosynthesis without affecting the metabolism of soft bottom benthos.

Results of wave modelling for Moreton Bay, Southeast Queensland, and a reef lagoon off Lizard Island, Great Barrier Reef, Australia

The distribution, abundance, behaviour, and morphology of marine species is affected by spatial variability in the wave environment. Maps of wave metrics (e.g. significant wave height Hs, peak energy wave period Tp, and benthic wave orbital velocity URMS) are therefore useful for predictive ecological models of marine species and ecosystems. A number of techniques are available to generate maps of wave metrics, with varying levels of complexity in terms of input data requirements, operator knowledge, and computation time. Relatively simple "fetch-based" models are generated using geographic information system (GIS) layers of bathymetry and dominant wind speed and direction. More complex, but computationally expensive, "process-based" models are generated using numerical models such as the Simulating Waves Nearshore (SWAN) model. We generated maps of wave metrics based on both fetch-based and process-based models and asked whether predictive performance in models of benthic marine habitats differed. Predictive models of seagrass distribution for Moreton Bay, Southeast Queensland, and Lizard Island, Great Barrier Reef, Australia, were generated using maps based on each type of wave model. For Lizard Island, performance of the process-based wave maps was significantly better for describing the presence of seagrass, based on Hs, Tp, and URMS. Conversely, for the predictive model of seagrass in Moreton Bay, based on benthic light availability and Hs, there was no difference in performance using the maps of the different wave metrics. For predictive models where wave metrics are the dominant factor determining ecological processes it is recommended that process-based models be used. Our results suggest that for models where wave metrics provide secondarily useful information, either fetch- or process-based models may be equally useful.

Sedimentology of a profile from Etoliko Lagoon, Western Greece

A key feature of Greece is the large amount of historical and archaeological records. The sedimentary record of the Etoliko Lagoon, Aetolia, Western Greece, offers an ideal opportunity to study human-environment interaction and to disentangle natural and anthropogenic imprints in the sedimentary record. By applying an interdisciplinary approach of combining geoscientific methods (XRF, LOI, grain size analysis) with archaeological and historical records, the 8.8 m long sedimentary sequence ETO1C reveals the palaeoenvironmental history of the lagoon and its catchment since 11,670 cal BP. With a thorough chronology based on 14C age-depth-modelling including varve counting, different evolutionary stages were put in a chronological context. These stages include a lake period (11,670-8310 cal BP) followed by a period of sporadic saltwater intrusion (8310-1350 cal BP) as a result of continuing transgression. Phases of limnic predominance associated with freshwater inflow of episodically activated distributaries (around 5230 cal BP) still occurred. By 1350 cal BP, ongoing sea level rise had connected the lagoons of Etoliko and Messolonghi and freshwater influence had ceased. With the onset of settlement activity in the Late Helladic (1700-1100 cal BC) humans took advantage of the prevailing environmental landscape. A sudden increase in coarse sedimentation correlates with the history of human occupation with its peak of prosperity from the Late Helladic until the end of the Hellenistic Period (30 cal BC).

Seawater carbonate chemistry and calcification during a tropical lagoon study at SW lagoon of New Caledonia, 1994

Carbon dioxide and oxygen fluxes were measured in 0.2 m2 enclosures placed at the water sediment interface in the SW lagoon of New Caledonia. Experiments, performed at several stations in a wide range of environments, were carried out both in darkness to estimate respiration and at ambient light, to assess the effects of primary production. The community respiratory quotient (CRQ = CO2 production rate/02 consumption rate) and the community photosynthetic quotient (CPQ= gross O2 production rate/gross CO2 consumption rate) were calculated by functional regressions. The CRQ value, calculated from 61 incubations, was 1.14 (S.E. 0.05) and the CPQ value, obtained from 18 incubations, was 1.03 (S.E. 0.08). The linearity of the relationship between the O2 and the CO2 fluxes suggests that these values are representative for the whole lagoon