Comparison of heat-shock responses between the hydrothermal vent shrimp Rimicaris exoculata and the related coastal shrimp Palaemonetes varians

The deep-sea vent shrimp Rimicaris exoculata is believed to occur at the hot end of the hydrothermal biotope in order to provide essential elements to its epibiosis. Because it is found close to hot venting water, R. exoculata lives in a highly fluctuating environment where temperature (2–40 °C in the swarms) can exceed its critical maximal temperature (33–38.5 ± 2 °C). In order to understand how this vent shrimp copes with hyperthermia, we compared its molecular heat stress response following an acute but non-lethal heat-shock (1 h at 30 °C) with that of its monophyletic shallow-water relative, the shrimp Palaemonetes varians, known to frequently undergo prolonged exposure at temperatures up to 30 °C in its natural environment during summer. We isolated four isoforms of heat-shock proteins 70 (HSP70) in R. exoculata (2 constitutive and 2 inducible isoforms) and two isoforms in P. varians (1 constitutive and 1 inducible isoform) and quantitatively compared their magnitude of induction at mRNA level, using real-time PCR, in the case of experimentally heat-stressed shrimps, with respect to control (unstressed) animals. Here, we report the first quantification of the expression of multiple hsp70 genes following heat stress in a deep-sea vent species living at 2300 m depth. Our results show a strong increase of hsp70 inducible genes in the vent shrimp (not, vert, similar 400-fold) compared to the coastal shrimp (not, vert, similar 15-fold). We therefore propose that, the highly inducible molecular response observed in R. exoculata may contribute to the ability of this species to tolerate thermal extremes

Practical measures for reducing phosphorus and faecal microbial loads from onsite wastewater treatment system discharges to the environment:a review

Onsite wastewater treatment systems (OWTS), the majority of which are septic tanks, are a contributing factor to phosphorus and faecal microbial loads. OWTS contribute to waterbodies failing to meet Water Framework Directive (WFD) objectives and as such, measures to improve the quality of OWTS discharges are required. Literature has been reviewed for a range of measures designed to reduce phosphorus and pathogen concentrations in effluent from OWTS. A feasibility assessment focussed on their application, effectiveness, efficiency, cost and ease of adaptation. A wide range of measures have been identified that could potentially improve water quality. Results show no one solution could be applied to reduce phosphorus and pathogen loadings to the water environment. The literature suggests that OWTS need to be designed to the local flow and load characteristics of the effluents streams,as well as site specific conditions. With that in mind, measures such as awareness raising, site planning, and maintenance are likely to contribute to reduction of impact of OWTS on the environment. The level of load reduction possible from measures such as awareness raising is difficult to quantify, but it is low-cost and relatively easy to implement. Those most effective for phosphorus and pathogen removal are post-tank measures that maximise physical removal, through adsorption and filtering, and maintain good conditions for biological breakdown of solids and predation of pathogens