Search

Copepods dominate the zooplankton community on the broad Agulhas Bank off southern Africa, where they provide an important food resource for pelagic fish and other biota. Previous studies have shown the dominant copepodCalanus agulhensis, which may comprise up to 80% of copepod biomass, to be strongly associated with the productive cold ridge of upwelled water on the central (CAB) and eastern (EAB) Agulhas Bank. However, there is little information available on other copepod taxa, and whether the Agulhas Bank community has changed over time in response to environmental variability or other ecosystem changes, such as the recent eastward shift in pelagic fish distribution. We use in situ temperature, chlorophylla(chla), and zooplankton data collected annually in late spring to explore spatio-temporal variability in copepod biomass and species composition on the Agulhas Bank over a 24-year period, from 1988 to 2011. Functional traits were used to interpret the observed patterns. Total copepod abundance and biomass were concentrated on the outer central and eastern shelf (>100m), coincident with the region of elevated chlaat 30m, and largely downstream from cooler subsurface water linked to the cold ridge and coastal upwelling. Current and cruise-feeding herbivoresC. agulhensisand the smaller Para- and Clausocalanidae collectively accounted for 73% and 54% of total copepod biomass and abundance respectively, driving the main patterns for total biomass.C. agulhensiscopepodites showed an ontogenetic shift in distribution with distance offshore and downstream from the cold ridge, and accumulation of older stages near the southern tip of the bank. The upwelling specialistCalanoides nataliswas closely associated with shelf-edge upwelling, particularly near the Agulhas Bight, but was low in biomass compared to the Benguela upwelling system. The current/cruise-feeding detritivoresMetridia lucensand the Oncaeidae were largely associated with the western sector of the bank but showed different niche preferences.M. lucensinhabited the chl-rich outer bank of the western Agulhas Bank (WAB), likely a continuation of the southern Benguela upwelling system community, while oncaeid biomass was associated with deeper thermoclines across the WAB and western part of the CAB that often feature accumulations of the gelatinous zooplankton they feed on.Centropagesspp. and the Oithonidae, mainly omnivorous ambush feeders, were associated with the inner to mid-shelf region of the WAB and CAB, away from the main influence of the Agulhas Current.Centropagesbiomass aligned well with elevated chlaon the inner WAB, likely an extension of the Benguela community (C. brachiatus), and with the cold ridge over the inner CAB shelf, matching earlier patterns linked toC. chierchiae. Oithonidae were widespread but low in biomass, and scarce over the Agulhas Current-influenced outer shelf, suggesting a suboptimal environment overall for this group compared to the cooler Benguela upwelling region. Current-feeding and omnivorousPleuromammaspp., known to be deep vertical migrators, were concentrated beyond the WAB shelf edge. Total copepod biomass showed a significant decline over the entire Agulhas Bank during the 24-year time series, as did all stages ofC. agulhensis, including large nauplii, and the small calanoids (Paracalanidae and Clausocalanidae). No long-term trends were observed for the other copepod taxa. We found no trends in temperature, but a significant but weak (1.5% yr−1) increase in chlaat 30m. Although there was no obvious shift in copepod biomass in response to the eastward shift in pelagic fish in ca. 1996, there were significant negative relationships between copepod biomass (for total copepods andC. agulhensis) and pelagic fish biomass (total, anchovy and redeye) from 1988 to 2011, with significantly lower copepod biomass after 1998 compared to before. This suggests predation pressure has an important top-down influence on copepod biomass on the Agulhas Bank. Bottom-up forcing from environmental drivers cannot be ruled out, however, despite ambiguous results from in situ and remote data series, and long-term warming due to climate change is expected to negatively impact ecosystem productivity at the large scale.

1968, 69, 70 – diese Jahre stehen nicht nur für globale Umbrüche und für Prozesse gesellschaftlicher Liberalisierung und kulturellen Wandels, sondern markieren in der Geschichte volkskundlicher Kulturwissenschaft eine Periode der Revolte und Reform. Spätestens auf der Detmolder Arbeitstagung, zu der sich die Deutsche Gesellschaft für Volkskunde (dgv) vom 22. bis 27. September 1969 versammelt hatte, eskalierten die Debatten um Herkunft, Selbstverständnis und Zukunft des Fachs. Der vorliegende Band rekonstruiert die Ereignisse von Detmold 1969 aus Quellen und Erinnerungen und nimmt auch die dabei relevanten internationalen Horizonte der Anthropologien in den Blick.

Climate change effects on the Baltic Sea environment are manifold. It is for example expected that water temperature and sea level will rise, and sea ice cover will decrease. This will affect ecosystems and biota; for example, range shifts are expected for a number of marine species, benthic productivity will decrease, and breeding success of ringed seals will be reduced. The impacts will hence affect the overall ecosystem function and also extend to human uses of the sea; trawling will follow the fish towards southern areas, aquaculture will likely face a shift towards species diversification, and the value of most ecosystem services is expected to change — to name a few. This Climate Change Fact Sheet provides the latest scientific knowledge on how climate change is currently affecting the Baltic Sea and how it is expected to develop in the foreseeable future. It is aimed at guiding policy makers to take climate change into account, but also to the general public. Updated Baltic Sea Climate Change Fact Sheets are expected to be published approximately every seven years.

No abstract available, Scandinavian Journal of Laboratory Animal Sciences, Vol. 13 No. 4 (1986)