Copepod oxygen consumption along a salinity gradient

Abstract

Climate change induced salinity decrease is currently occurring in many estuarine coastal zones, due to increased outflow of freshwater. This freshening can be a problem for brackishwater animals, already living on the edge of their salinity tolerance. In the current study, we measured oxygen consumption of common copepod Eurytemora affinis (hereafter E. affinis) along a natural salinity gradient in the western Gulf of Finland. The salinity varied between 3 in the inner bay and 7 in the offshore area along the gradient, and pH varied between 7.05 and 7.86. Our results show that respiration increased with decreasing salinity, as expected for a genus more commonly found in estuarine/saline waters, even if it has colonised brackish waters.

A study of the feeding characteristics of a small and medium-sized copepod species (Sinocalanus tenellus) using genetic analysis techniques: seasonal comparison of potential/eaten food sources focused on phytoplankton

“…Copepod feeding characteristics are primarily obtained from seawater species, such as the genus Calanus, whose gut contents are relatively easy to sort and extract because of their large size (Gabrielsen et al, 2012). Conversely, in the case of small-and medium-sized copepods dominant in brackish water, it is difficult to analyse food sources in the same way as for large copepods, resulting in limited information on their feeding characteristics (Mäkinen et al, 2017;Souliéet al, 2022). In addition, when gut contents are extracted, there is a risk of contamination from external unnecessary genes or loss of genes in the gut contents.…”