Description: Potential and relative potential fecundity of 701 cod Gadus morhua caught in the Bornholm Basin (ICES Sub-division 25) during 1987–1996 and 106 from the Gdansk Deep (ICES Sub-division 26) in 1995 and 1996 varied significantly between years but neither between different spawning grounds nor between different sampling months within one spawning season. Growth and water temperature are factors identified to influence the mean relative fecundity explaining 66% of the variance between years.

Description: Climate variability in the northeast Atlantic was investigated on glacial–interglacial and millennial time scales during the last 200 000 years, using sea surface temperature (SST) records derived from planktonic foraminiferal diversities and from Mg/Ca measurements on Globigerina bulloides. Paleoceanographical interpretations are supported by species composition analyses, benthic and planktonic isotopic data as well as records of iceberg-rafted debris (IRD). Differences of climate development are recognized for both interglacial and glacial periods. Temperature estimates indicate slightly warmer conditions (up to 2°C) during marine oxygen isotope stage (MIS) 5e than during the Holocene. In contrast to the last glaciation, when the SST minimum coincided with a minimum in solar insolation immediately before Termination I, during the penultimate glaciation a long SST minimum occurred at times of intermediate solar insolation well preceding the onset of Termination II. This discrepancy between two glacial terminations may be explained by an inherently different orbital configuration characteristic for each glacial interval. Despite these differences between the two glacial trends, the superimposed shorter-lived climatic events reveal the same order of principal steps, implying their common causal nature. A direct comparison of faunal SSTs with those retrieved from Mg/Ca analysis shows that Mg/Ca-derived temperatures follow the general glacial–interglacial trend; however, the latter appear to be largely overestimated. Supported by δ18O data in G. bulloides, which show little response to millennial-scale variability, there seems to be a need for species-dependent calibration experiments that also consider the different oceanographic settings this particular species can live in.

Description: During peak spawning of sprat Sprattus sprattus in the Baltic Sea in May–June egg specific gravity averaged ±s.d. 1·00858 ± 0·00116 g cm−3 but was significantly higher in the beginning and significantly lower towards the end of the spawning season. A close relationship was found between egg diameter and egg specific gravity (r2 = 0·71). This relationship, however, changed during the spawning season indicating that some other factor was involved causing the decrease in specific gravity during the spawning period. The vertical egg distribution changed during the spawning season: eggs were distributed mainly in the deep layers early in the season, occurred in and above the permanent halocline during peak spawning, and above the halocline towards the end of the spawning season. Consequently, poor oxygen conditions in the deep layers and low temperatures in layers between the halocline and the developing thermocline may affect egg development. Thus, opportunities for egg development vary over the spawning season and among spawning areas, and depending on frequency of saline water inflows into the Baltic Sea and severity of winters, between years

Description: The δ18O values of planktonic foraminifera increased in the Caribbean by about 0.5‰ relative to the equatorial East Pacific values between 4.6 and 4.2 Ma as a consequence of the closure of the Central American Gateway (CAG). This increase in δ18O can be interpreted either as an increase in Caribbean sea surface (mixed layer) salinity (SSS) or as a decrease in sea surface temperatures (SST). This problem represents an ideal situation to apply the recently developed paleotemperature proxy δ44/40Ca together with Mg/Ca and δ18O on the planktic foraminifer Globigerinoides sacculifer from ODP Site 999. Although differences in absolute temperature calibration of δ44/40Ca and Mg/Ca exist, the general pattern is similar indicating a SST decrease of about 2–3 °C between 4.4 and 4.3 Ma followed by an increase in the same order of magnitude between 4.3 and 4.0 Ma. Correcting the δ18O record for this temperature change and assuming that changes in global ice volume are negligible, the salinity-induced planktonic δ18O signal decreased by about 0.4‰ between 4.4 and 4.3 Ma and increased by about 0.9‰ between 4.3 and 4.0 Ma in the Caribbean. The observed temperature and salinity trends are interpreted to reflect the restricted exchange of surface water between the Caribbean and the Pacific in response to the shoaling of the Panamanian Seaway, possibly accompanied by a southward shift of the Intertropical Convergence Zone (ITCZ) between 4.4 and 4.3 Ma. Differences in Mg/Ca- and δ44/40Ca-derived temperatures can be reconciled by corrections for secular variations of the marine Mg/Casw and δ44/40Ca, a salinity effect on the Mg/Ca ratio and a constant temperature offset of ∼2.5 °C between both SST proxy calibrations.