No abstract available

[en] Highlights: • Recent thermal history alters thermal tolerance and survival in marine amphipods. • Species composition of epifaunal assemblage can shift seasonally. • Impacts of extreme stress will depend on local species composition and timing relative to recent climate conditions. Marine heatwaves are occurring with greater frequency and magnitude worldwide and can significantly alter community structure and ecosystem function. Predicting changes in community structure in extreme temperatures requires an understanding of variation among species in their thermal tolerance, and how potential acclimatization to recent temperatures influences survival. To address this, we determined the tolerance to extreme temperatures in a crustacean epifaunal assemblage that inhabits macroalgae in the southeast Australian ocean warming hotspot. Amphipods were the most abundant group and the thermal tolerance of the most abundant species (two in winter and four in summer) was tested to determine their thermal limits and probability of survival in near-future extreme temperatures. Survival, measured as time to immobilization, was compared across species, sexes, life stage and body size. The greatest variation in tolerance to extreme temperatures was among species (not body sizes or life stages), indicating that heatwaves could shift the composition of the macroalgal associated epifaunal assemblage. Comparison of recent thermal history (between 18 °C to 22 °C) revealed greater thermal tolerance of warm acclimatized individuals. Our results indicate that the impacts of a marine heatwave will depend on local species composition and their timing relative to recent climate conditions.

No abstract available

[en] Uptake of tritiated water (HTO) by Orconectes immunis was investigated under laboratory conditions. Tritium uptake in the tissue-free water fraction (TFWT) was described using an exponential model. When steady-state was reached, the ratio of TFWT to HTO was approximately 0.9. Uptake of tritium in the organically-bound fraction (OBT) proceeded slowly, and had not reached steady-state after 117 days of culture. Although steady-state was never reached, the maximum observed ration of OBT to TFWT in whole animals was approximately 0.6. However, this ratio exceeded unity in the exoskeleton. Specific activity ratios of OBT between crayfish and lettuce (food source) were less than or at unity for various test conditions

[en] The influence of two salt concentration 0.85% and 3% NaCl, on the radiosensitivity of 3 cultures of Vibrio parahaemolyticus K₃, K₁₃, and K₂₈, incoulated into sterile crab meat and pealed shrimp homogerntes was investigated. In peeled shrimp, with 0.85% NaCl, its D₁₀ values for strains K₃, K₁₃ and K₂₈ were 57.1+-0.50, 62.6+-0.79, 47.9+-0.43 Gy, respectively. The variation of the strains was increased in 3% salt concentration with D₁₀ values of 80.5+-0.88, 73.3+-1.04, 52.8+-0.44 Gy, for strains K₃, K₁₃ and K₂₈, respectively. For the crab meat honagenate with 0.85% NaCl, its D₁₀ value for strains K₃ and K₁₃ were 57.8+-0.72 and 52.1+-0.96 Gy, and the values for 3% NaCl were 70.0+-0.12 and 52.7+-0.82 Gy, respectively. In most cases the complete destruction was obtained with 50-60 kGy. Vibrio parahaemolyticus in seafood could be readily controlled by radicidation

[en] Larvae of a brachyuran crab, Cancer irroratus, were cultured at constant and cyclic temperatures. Survival of all the larval stages cultured at 10 to 20⁰C and at 15 to 25⁰C cycles was better than that of larvae grown at comparable constant temperatures. At the 12.5 to 17.5⁰C cycle, the survival of larvae was less than that at the comparable 10 to 20⁰C cycle. Larvae cultured at the 17.5 to 22.5⁰C cycle developed only to the megalops stage. Duration of the zoeal stages at both 12.5 to 17.5⁰C and 10 to 20⁰C cycles decreased and of the megalops stage increased when compared to that at constant 15⁰C. The duration of the megalops stage increased considerably at the 15 to 25⁰C cycle compared to that at constant 20⁰C. In the larval development of C. irroratus, megalops is a more sensitive stage than the earlier ones. The amplitude and rate of temperature change have affected differently the duration and survival of the zoeal and megalops stages. Variable temperatures of a favorable amplitude and rate of change within the normal range for development appear to confer a greater capacity for tolerance and survival than comparable constant temperatures

[en] Gammarus spp. (G. daiberi and G. tigrinus) experienced no increased latent mortalities for periods up to 10 days after being exposed to an 8.3C ΔT above an ambient temperature of 25.5C for periods up to 60 minutes. An 11.1C ΔT above an ambient temperature of 26.5 C resulted in significant reductions in survival in groups of Gammarus spp. exposed for 30 and 60 minutes. No significant mortalities were observed, however, following a 5-minute exposure to the 11.1 C ΔT. At an ambient temperature of 11.7 C, Gammarus spp. exposed to 16.7 C ΔT's for periods up to 180 minutes displayed no increased mortalities 10 days after exposure. A sustained 17-day exposure of Gammarus spp. to a 15.6 C ΔT at ambient temperatures of 11.2 to 7.1 C resulted in no increased mortalities and stimulated reproductive behavior. Subsequent reproductive activities were not affected by up to 60-minute exposures of mature Gammarus spp. to an 8.3C ΔT at an ambient temperature of 26.0 C. The same exposure also did not affect the release of young by ovigerous female Gammarus spp. An 11.0 C ΔT for 30 minutes resulted, however, in almost no release of young from ovigerous females

[en] Highlights: • Coastal armoring is a common societal response to shoreline erosion around the world • Armoring placed on sandy beaches can affect multiple ecosystem features and functions. • Evaluated effects of coastal armoring on mobile macroinvertebrates across intertidal zones on beaches of Chile and California • Armoring effects on fauna increased from the low to the upper intertidal zones • The number of intertidal zones affected by armoring depended on its location on the beach profile, armoring located lower on the profile affected a greater number of intertidal zones Coastal armoring is widely applied to coastal ecosystems, such as sandy beaches, in response to shoreline erosion and threats to infrastructure. Use of armoring is expected to increase due to coastal population growth and effects of climate change. An increased understanding of armoring effects on those ecosystems and the services they provide is needed for impact assessments and the design of these structures. We investigated the following hypotheses: 1) impacts of coastal armoring on beach macroinvertebrates increase from lower to upper intertidal zones and 2) location of an armoring structure on beach profiles affects the number of intertidal zones, using comparative surveys of armored and unarmored beach sections in Chile and California. The effects of armoring were greater for upper intertidal (talitrid amphipods) and mid-intertidal species (cirolanid isopods) than for lower shore fauna (hippid crabs). Our surveys of sections of armoring structures located higher and lower on the beach profile (with and without interactions with waves and tides), showed loss of upper zone talitrid amphipods and mid-zone isopods and a reduction of lower zone hippid crabs in sections where the structures were lower on the beach profile and interacted with waves, compared to non-interacting sections. Our results support the hypothesis that impacts of armoring on intertidal macroinvertebrates increase from the lower to the upper intertidal zones of sandy beaches and also suggest that the relative position of an armoring structure on the beach profile, determines the number of intertidal zones it affects. Our findings also imply that by altering the position of existing armoring structures on the shore profile and increasing the amount of interaction with waves and tides, sea level rise and regional factors, such as coseismic coastal subsidence, can be expected to exacerbate the impacts of these widely used coastal defense structures on sandy beach ecosystems.

No abstract available

[en] The uptake and loss kinetics of sup(95m)Tc in seawater have been investigated in the crab Pachygrapsus marmoratus. Both the uptake and loss kinetics can be represented as the sum of two exponential functions, one short-term (tbsub(1/2)=16 d) and one long-term (tbsub(1/2)=63 d), tbsub(1/2) being the biological half-time. The predicted steady state concentration factor was estimated to be about 18. No significant linear correlation between Tc uptake rate and animal weight was found during the accumulation phase. At the end of this phase, 77% of the Tc was found to be distributed in the digestive system and particularly in the hepatopancreas (56%); this organ also appeared to lose the radionuclide most quickly. During the loss phase, 90% of the incorporated radioactivity was eliminated in about three months. Therefore P. marmoratus does not appear to be a good bioindicator of Tc in the marine environment nor an important pathway for Tc contamination along marine food chains. (author)