scholarly journals Decline in Thermal Habitat Conditions for the Endangered Delta Smelt as Seen from Landsat Satellites (1985–2019)

Author(s):  
Gregory H. Halverson ◽  
Christine M. Lee ◽  
Erin L. Hestir ◽  
Glynn C. Hulley ◽  
Kerry Cawse-Nicholson ◽  
...  
2009 ◽  
Vol 57 (5) ◽  
pp. 357 ◽  
Author(s):  
John Eme ◽  
Wayne A. Bennett

We measured metabolic rates of six Indo-Pacific fishes from different thermal habitats at 26°C and after acute transfer to 32°C. Temperature–metabolism relationships were expressed as temperature quotients (Q10) and ranged from ~1.0 in tidepool-dwelling common (Bathygobius fuscus) and sandflat (Bathygobius sp.) gobies to 2.65 and 2.29 in reef-associated white-tailed humbug (Dascyllus aruanus) and nine-banded cardinalfish (Apogon novemfasciatus), respectively. Squaretail mullet (Liza vaigiensis) and blackspot sergeant (Abudefduf sordidus) displayed Q10 responses of 2.03 and 1.26, respectively. Bathygobiids and blackspot sergeant inhabit mangrove tidepools during daytime low tides and experience temperature fluctuations approximately twice (12°C) the maximum experienced by inhabitants of patch reef or seagrass and squaretail mullet (1–6°C), a mangrove transient that avoids shallow, insolated daytime low tides. The low Q10 responses of the bathygobiids and blackspot sergeant suggest that their metabolic rates are relatively temperature-insensitive over the thermal range tested. Our data support the hypothesis that fish metabolic responses are tailored to specific thermal habitat conditions.


2020 ◽  
Author(s):  
Ted Sommer ◽  
Rosemary Hartman ◽  
Michal Koller ◽  
Michael Koohafkan ◽  
J. Louise Conrad ◽  
...  

AbstractWhile flow is known to be a major driver of estuarine ecosystems, targeted flow manipulations are rare because tidal systems are extremely variable in space and time, and because the necessary infrastructure is rarely available. In summer 2018 we used a unique water control structure in the San Francisco Estuary (SFE) to direct a managed flow pulse into Suisun Marsh, one of the largest contiguous tidal marshes on the west coast of the United States. The action was designed to increase habitat suitability for the endangered Delta Smelt Hypomesus transpacificus, a small osmerid fish endemic to the upper SFE. The approach was to operate the Suisun Marsh Salinity Control Gates (SMSCG) in conjunction with increased Sacramento River tributary inflow to direct an estimated 160 × 106 m3 pulse of low salinity water into Suisun Marsh during August, a critical time period for juvenile Delta Smelt rearing. Three-dimensional modeling showed that directing additional low salinity water into Suisun Marsh (“Flow Action”) substantially increased the area of low salinity habitat for Delta Smelt that persisted beyond the period of SMSCG operations. Field monitoring showed that turbidity and chlorophyll were at higher levels in Suisun Marsh, representing better habitat conditions, than the upstream Sacramento River region throughout the study period. The Flow Action had no substantial effects on zooplankton abundance, nor did Suisun Marsh show enhanced levels of these prey species in comparison to the Sacramento River. Fish monitoring data suggested that small numbers of Delta Smelt colonized Suisun Marsh from the Sacramento River during the Flow Action, further supporting our hypothesis that the Flow Action would benefit this rare species. Our study provides insight into both the potential use of targeted flow manipulations to support endangered fishes such as Delta Smelt, and into the general response of estuarine habitat to flow management.


Water ◽  
2021 ◽  
Vol 13 (18) ◽  
pp. 2586
Author(s):  
Christos Theodoropoulos ◽  
Ioannis Karaouzas ◽  
Anastasios Stamou

What would happen in Mediterranean rivers and streams if warming but not drying occurred? We examined whether the delivery of environmental flows within a warming climate can maintain suitable macroinvertebrate habitats despite warming. A two-dimensional ecohydraulic model was used to (1) simulate the influence of water temperature and flow on macroinvertebrates by calculating habitat suitability for 12 climate change scenarios and (2) identify the mechanism by which macroinvertebrate assemblages respond to warming. The results suggest that not all watersheds will be equally influenced by warming. The impact of warming depends on the habitat conditions before warming occurs. Watersheds can, thus, be categorized as losing (those in which warming will degrade current optimal thermal habitat conditions) and winning ones (those in which warming will optimize current sub-optimal thermal habitat conditions, until a given thermal limit). Our models indicate that in losing watersheds, the delivery of environmental flows can maintain suitable habitats (and, thus, healthy macroinvertebrate assemblages) for up to 1.8–2.5 °C of warming. In winning watersheds, environmental flows can maintain suitable habitats when thermal conditions are optimal. Environmental flows could, thus, be used as a proactive strategy/tool to mitigate the ecological impacts of warming before more expensive reactive measures within a changing climate become necessary.


2020 ◽  
Vol 736 ◽  
pp. 139679
Author(s):  
Valerie Ouellet ◽  
André St-Hilaire ◽  
Stephen J. Dugdale ◽  
David M. Hannah ◽  
Stefan Krause ◽  
...  

Author(s):  
Yuriy Borisovich Lvov

The article touches upon the principles, biological basics and practical progress of introduction of specific and age polyculture of fishes. Using the results of the analysis of literary and long-term native data, there has been offered the gradation of 12 fish species from different families by resistance to habitat conditions. Crucian ( Carassius gibelio ) has been chosen as the most sustainable object of cultivation. There has been taken an attempt to calculate the number of seeding different fish species in polyculture taking into account their physiological features is made. Subject to specific physiological features of the studied species, there was carried out recalculation of their natural reproductive performance in different fish-breeding zones, which is traditionally carried out for a carp ( Cyprinus carpio ). In particular, in the second fish-breeding zone with area of 1 hectare it is possible to breed 120 kg of carp, or 150 kg of crucian, or 75 kg of silver carp ( Hypophthalmichthys ). Overall productivity is made up of a share of fishes in polyculture, but taking into account tolerance of species, it can be lower than productivity calculated for carp. The method of calculation and formulas which give the chance to determine seeding density of fish species for breeding in polyculture have been offered. This technique makes it possible to use trophic preferences and consider tolerance of each species to the conditions of breeding areas.


2009 ◽  
Vol 24 (1) ◽  
pp. 43-59
Author(s):  
Magdalena Jastrzębska ◽  
Tadeusz Szarejko ◽  
Czesław Hołdyński ◽  
Wiesław Piotr Jastrzębski

2021 ◽  
pp. 1-16
Author(s):  
Jérémie Boudreault ◽  
André St-Hilaire ◽  
Fateh Chebana ◽  
Normand E. Bergeron

Author(s):  
Karina Dias-Silva ◽  
Thiago Bernardi Vieira ◽  
Talissa Pio de Matos ◽  
Leandro Juen ◽  
Juliana Simião-Ferreira ◽  
...  

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