SEARCH · USGS Science

Results for “Marine and Freshwater Behaviour and Physiology”

Search indexed USGS publications on groundwater, aquifers, geologic maps, mineral resources and earthquakes. Explore source records by subject and place.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

3 recordsLinked to original sources

USGS2013

Burrowing, byssus, and biomarkers: behavioral and physiological indicators of sublethal thermal stress in freshwater mussels (Unionidae)

Recent research has elucidated the acute lethal effects of elevated water temperatures to glochidia (larvae), juvenile, and adult life stages of freshwater mussels (Order Unionida), but few studies have focused on sublethal effects of thermal stress. We evaluated the sublethal effects of elevated temperature on burrowing behavior and byssus production in juveniles, and on enzymatic biomarkers of stress in adults in acute (96 h) laboratory experiments in sediment, with two acclimation temperatures (22 and 27 °C) and two experimental water levels (watered and dewatered) as proxies for flow regime. Increasing temperature significantly reduced burrowing in all five species tested, and the dewatered treatment (a proxy for drought conditions) reduced burrowing in all but Amblema plicata . Production of byssal threads was affected most drastically by flow regime, with the probability of byssus presence reduced by 93–99% in the dewatered treatment, compared to the watered treatment (a proxy for low flow conditions); increasing temperature alone reduced byssus by 18–35%. Alanine aminotransferase and aspartate aminotransferase were significantly affected by treatment temperature in the 27 °C acclimation, watered test ( p =  0.04 and 0.02, respectively). Our results are important in the context of climate change, because stream temperature and flow are expected to change with increasing air temperature and altered precipitation patterns.

Marine and Freshwater Behaviour and Physiology↗

USGS2017

Osmoregulation and muscle water control in vitro facing salinity stress of the Amazon fish Oscar Astronotus ocellatus (Cichlidae)

Specimens of Oscar Astronotus ocellatus from a fish farm were abruptly submitted to salt stress of 14 ppt and 20 ppt, for 3 and 8 h to determine their plasma osmolality. Muscle wet body mass change in vitro was analyzed from control freshwater animals. Fish in 14 ppt presented no osmolality distress even after 8 h. In 20 ppt, a slight increase (10%) in plasma osmolality was observed for both times of exposure when compared to control fish. Muscle slices submitted in vitro to hyper-osmotic saline displayed decreased body mass after 75 min, and slices submitted to hypo-osmotic saline displayed increased body mass after 45 min when compared to control (isosmotic saline). These results reinforce A. ocellatus ’s euryhalinity. The fish were able to regulate its internal medium and tolerate 14 ppt, but presented an intense osmotic challenge and low muscle hydration control when facing salinities of 20 ppt.

Marine and Freshwater Behaviour and Physiology↗

USGS2020

Atlantic salmon (Salmo salar) exposed to different preparatory photoperiods during smoltification show varying responses in gill Na+/K+-ATPase, salinity-specific mRNA transcription and ionocyte differentiation

Control of the parr-smolt transformation (or smoltification) is crucial for the husbandry and successful seawater (SW) transfer of Atlantic salmon ( Salmo salar ) reared in freshwater (FW) hatcheries. Photoperiod is an important environmental signal that initiates the complex physiological, morphological and behavioural changes that coincide with marine migration. While the use of long-day photoperiods to initiate smoltification has been well studied, this study investigated how three preparatory photoperiods in FW (LD 08:16, LD 12:12, LD 16:08) preceding exposure to 24-h light (LD 24:0) may influence or enhance smolt performance and growth post-SW transfer. After the photoperiod treatment phase (8 weeks), all groups were exposed to LD 24:0 for 8 weeks (FW) and then transferred to SW for a further 8 weeks. Exposure to LD 16:08 induced rapid development of smolt-related characteristics such as increased gill NKA activity, gill NKAα1b mRNA, and plasma cortisol, and decreased gill NKAα1a mRNA levels and condition factor through the 8-week treatment phase. Subsequent exposure to a LD 24:0 photoperiod resulted in a partial reversal of several of these characteristics, suggesting these fish went through a partial desmoltification. Exposure to LD 12:12 for 8 weeks prior to LD 24:0 elicited an intermediary response in smoltification attributes compared to LD 16:08 and LD 08:16. The LD 12:12 group adapted to SW and showed no negative effects on growth or physiological responses after transfer to SW. Exposure to a shortened photoperiod (LD 08:16) did not elicit any smoltification-related changes prior to LD 24:0, however, exposure to LD 24:0 increased gill NKA activity, plasma cortisol, changes in NKAα1a and NKAα1b mRNA, and the ratio of NKAα1b: NKAα1a. These results were confirmed by the expected changes in NKAα1a and NKAα 1b-positive immuno-reactive gill ionocytes. In summary, after exposure to LD 24:0 fish in the LD 08:16 group showed similar levels of change to those of the LD 16:08 group during the initial FW phase (prior to exposure to LD 24:0). After SW transfer, all groups were able to upregulate SW-specific NKAα1b mRNA and acclimate to SW, even though no increase in cortisol was evident. By the end of the study, there was no difference in SW growth among the groups. Overall, our data indicate that LD 16:08 advanced hypoosmoregulatory characteristics prior to LD 24:0 exposure. In addition, the physiological and molecular indicators measured in this group suggest that fish could have been transferred to SW immediately after 8 weeks in LD 16:08, with no added benefit of successive exposure to LD 24:0, which is typically used by industry to induce smoltification.

Aquaculture↗