Traditionally lower and upper temperature tolerances of fishes have been quantified in the laboratory via three different experimental approaches: the Fry or incipient lethal temperature (ILT), critical thermal (CTM) and chronic lethal (CLM) methodologies. Although these three experimental laboratory approaches generate endpoints which are quantitatively expressed as a temperature, are determined experimentally with random samples of fish acclimated to specific temperatures, and involve both time and temperature as major test variables, they do not quantify the same response. All three approaches generate valuable, albeit different, information concerning the temperature tolerance of a species. In this review we have summarized published research concerning the tolerance of North American freshwater fishes to dynamic changes in temperature, i.e., tolerance is tested by methods that gradually change temperatures until biological stress is observed. We found more than 450 individual temperature tolerances listed in 80 publications which present original dynamic temperature tolerance data for 116 species, 7 subspecies and 7 hybrids from 19 families of North American freshwater fishes. This total represents about 1/3 of the families and 1/6 of the known North American freshwater species. Temperature tolerance data were partitioned by experimental approach, i.e., critical thermal method (CTM) and chronic lethal method (CLM), and direction of temperature change. Although both CTM and CLM expose fish to dynamic changes in water temperature, these two methods differ in temperature change rates and test endpoints, and hence measure different aspects of thermal stress. A majority of the 80 studies employed CTM to assess temperature tolerance, in particular determination of CTmaxima. One or more CTmaxima has been reported for 108 fishes. Twenty-two fishes have reported highest CTmaxima of 40°C or higher. Several species in the family Cyprinodontidae have generated some of the highest CTmaxima reported for any ectothermic vertebrate. For a variety of reasons, data concerning tolerance of low temperatures are less plentiful. Low temperature tolerance quantified as either CTminima or CLminima were found for a total of 37 fishes. Acclimation temperature exerts a major effect on the temperature tolerance of most North American fish species and it is usually strongly linearly related to both CTmaxima and CTminima. Although we uncovered dynamic temperature tolerance data for 130 fishes, only a single dynamic, temperature tolerance polygon has been published, that for the sheepshead minnow, Cyprinodon variegatus.

Temperature Tolerances of North American Freshwater Fishes Exposed to Dynamic Changes in Temperature

Resistance surfaces are often used to fill gaps in our knowledge surrounding animal movement and are frequently the basis for modeling connectivity associated with conservation initiatives. However, the methods for quantifying resistance surfaces are varied and there is no general consensus on the appropriate choice of environmental data or analytical approaches. We provide a comprehensive review of the literature on this topic to highlight methods used and identify knowledge gaps. Our review includes 96 papers that parameterized resistance surfaces (sometimes using multiple approaches) for a variety of taxa. Data types used included expert opinion (n = 76), detection (n = 23), relocation (n = 8), pathway (n = 2), and genetic (n = 28). We organized the papers into three main analytical approaches; one-stage expert opinion, one-stage empirical, and two-stage empirical, each of which was represented by 43, 22, and 36 papers, respectively. We further organized the empir- ical approaches into five main resource selection functions; point (n = 16), matrix (n = 38), home range (n = 3), step (n = 1), and pathway (n = 1). We found a general lack of justification for choice of environmental variables and their thematic and spatial representation, a heavy reliance on expert opinion and detection data, and a tendency to confound movement behavior and resource use. Future research needs include comparative analyses on the choice of envi- ronmental variables and their spatial and thematic scales, and on the various biological data types used to estimate resistance. Comparative analyses amongst analytical processes is also needed, as well as trans- parency in reporting on uncertainty in parameter estimates and sensitivity of final resistance surfaces, especially if the resistance surfaces are to be used for conservation and planning purposes.

Estimating landscape resistance to movement: a review

Summary 1. I synthesize the understanding of the relationship between landscape structure and animal movement in human-modified landscapes. 2. The variety of landscape structures is first classified into four categories: continuous habitat, patchy habitat with high-quality matrix, patchy habitat with low-quality matrix, and patchy, ephemeral habitat. Using this simplification I group the range of evolved movement parameters into four categories or movement types. I then discuss how these movement types interact with current human-caused landscape changes, and how this often results in non-optimal movement. 3. From this synthesis I develop a hypothesis that predicts the relative importance of the different population-level consequences of these non-optimal movements, for the four movement types. 4. Populations of species that have inhabited landscapes with high habitat cover or patchy landscapes with low-risk matrix should have evolved low boundary responses and moderate to high movement probabilities. These species are predicted to be highly susceptible to increased movement mortality resulting from habitat loss and reduced matrix quality. 5. In contrast, populations of species that evolved in patchy landscapes with high-risk matrix or dynamic patchy landscapes are predicted to be highly susceptible to decreased immigration and colonization success, due to the increasing patch isolation that results from habitat loss. 6. Finally, I discuss three implications of this synthesis: (i) ‘least cost path’ analysis should not be used for land management decisions without data on actual movement paths and movement risks in the landscape; (ii) ‘dispersal ability’ is not simply an attribute of a species, but varies strongly with landscape structure such that the relative rankings of species’ dispersal abilities can change following landscape alteration; and (iii) the assumption that more mobile species are more resilient to human-caused landscape change is not generally true, but depends on the structure of the landscape where the species evolved.

Non‐optimal animal movement in human‐altered landscapes

Nature Conservation 2: The Role of Corridors

Models are commonly used to identify lands that will best maintain the ability of wildlife to move between wildland blocks through matrix lands after the remaining matrix has become incompatible with wildlife movement. We offer a roadmap of 16 choices and assumptions that arise in designing linkages to facilitate movement or gene flow of focal species between 2 or more predefined wildland blocks. We recommend designing linkages to serve multiple (rather than one) focal species likely to serve as a collective umbrella for all native species and ecological processes, explicitly acknowledging untested assumptions, and using uncertainty analysis to illustrate potential effects of model uncertainty. Such uncertainty is best displayed to stakeholders as maps of modeled linkages under different assumptions. We also recommend modeling corridor dwellers (species that require more than one generation to move their genes between wildland blocks) differently from passage species (for which an individual can move between wildland blocks within a few weeks). We identify a problem, which we call the subjective translation problem, that arises because the analyst must subjectively decide how to translate measurements of resource selection into resistance. This problem can be overcome by estimating resistance from observations of animal movement, genetic distances, or interpatch movements. There is room for substantial improvement in the procedures used to design linkages robust to climate change and in tools that allow stakeholders to compare an optimal linkage design to alternative designs that minimize costs or achieve other conservation goals.

http://corridordesign.org/dl/docs/Beier.Majka.Spencer.2008.ConsBiol.LinkageDesigns.pdf

Forks in the Road: Choices in Procedures for Designing Wildland Linkages

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Asian Carps of the Genus Hypophthalmichthys (Pisces, Cyprinidae) ― A Biological Synopsis and Environmental Risk Assessment

https://www.biologicaldiversity.org/programs/population_and_sustainability/urban_wildlands/pdfs/Kautz_et_al_2006_BiolCons.pdf

How much is enough? Landscape-scale conservation for the Florida panther

Cold tolerance and behavioral responses of blackchin tilapia, Sarotherodon melanotheron, to rapidly decreasing temperatures were investigated at salinities of 5, 15, and 35 parts per thousand (ppt). Cold tolerance did not significantly differ with salinity or social rank. Mean temperatures were 10.7° C for beginning loss of equilibrium, 9.6° C for complete loss of equilibrium, and 6.9° C for death at all salinities. Behavioral activity declined with decreasing temperature and ceased between 10–12° C. Certain behavioral actions were significantly more frequent at 15 or 35 ppt salinity than at 5 ppt. The northward range expansion by introduced populations of the blackchin tilapia in the United States probably will be limited by its lower lethal temperature limits, but may also be affected by temperatures at which social behavior becomes disrupted.

Behavioral aspects of cold tolerance in blackchin tilapia, Sarotherodon melanotheron, at different salinities

The blackchin tilapia, Sarotherodon melanotheron, was first collected from the Indian River system, in Brevard County, Florida, in 1980. Since its introduction, this species has expanded its range northward along the coast approximately 37 km, to just north of Whites Point, Brevard County, and southward about 68 km to Vero Beach, Indian River County. Laboratory studies on salinity tolerance indicate an ability of this species to tolerate hypersaline concentrations of at least 100 ppt, and to reproduce in salinities of up to 35 ppt. The northern distribution of blackchin tilapia is almost certainly limited by cold temperature; however, the potential exists for extensive coastal, and possibly inland, invasion south of Its present limits. The blackchin tilapia in the United States is an exotic cichlid fish, native to estuarine areas of west Africa from Senegal to Zaire (Trewavas 1983). This species was originally imported as an aquarium fish, but was released or escaped into the wild and became established in open waters. It currently is established in Florida on the west coast in the Tampa Bay area in Hillsborough and Manatee counties, anEf on the east coast in the Indian River lagoon system in Brevard and Indian River counties. Blackchin tilapia were first reported from Tampa Bay in 1959 (Springer and Finucane 1963). By 1962, the species was established and utilized as a small commercial fish (Finucane and Rinckey 1967). It continues to be exploited in the fishery today, from the eastern side of Tampa Bay southward to Cockroach Bay. The first collection of blackchin tilapia in the Indian River system was in 1980 near Satellite Beach, Brevard County (Dial and Wainwright 1983). It is unknown whether this population resulted from the release of aquarium or aquaculture fish, or whether tilapia were transplanted from the Tampa Bay population for sport fishing and bait potential. The blackchin tilapia is commonly taken by commercial 111 fishermen netting for mullet in the ·Indian and Banana rivers, and there is a local market for them. Although the blackchin tilapia has been present in these estuarine systems for many years, little is known about its life history. Because it is a tropical species, cold temperature is considered a primary environmental factor restricting its dispersal northward (Courtenay et al. 1981.). Knowledge of its reproductive behavior and survival over a range of salinities is also important for predicting its potential distribution in estuarine areas. We conducted field studies to determine the distribution and habitat requirements of blackchin tilapia in the Indian River system and to establish baseline data for monitoring the population at the extremes of its range. Laboratory studies were designed to investigate the primary factors influencing distribution in estuarine environments. These experiments were done following a previous study on temperature tolerance (Jennings 1991), to further enhance our knowledge of blackchin tilapia. This combined information will help predict potential range expansion of blackchin tilapia in the Indian 1 Jennings and Williams: Factors Influencing the Distribution of Blackchin Tilapia Sarothe Published by The Aquila Digital Community, 1991 112 Jennings, D. P. and J. D. Williams River and other estuarine systems. MATERIALS AND METHODS Study Area The Indian River system is essentially a long narrow estuarine lagoon, with little freshwater inflow, situated on the east coast of Florida. It extends 253 km, from Ponce de Leon Inlet near New Smyrna Beach, Vol usia County, south to Jupiter Inlet, Palm Beach Co. (Figure 1). It consists of 3 interconnected bodies of water Mosquito Lagoon, Indian River, and Banana River. Lagoons are separated from the Atlantic Ocean by narrow barrier beaches and by the Cape Canaveral and Merritt Island land masses. Ocean connections consist of 5 inlets: Ponce de Leon, Sebastian, Fort Pierce, St. Lucie and Jupiter. The width of this system varies from only a few meter>s at Jupiter to 8.9 km near Titusville (Gilmore 1977). Average depth is approximately 1.5 m. Salinity varies with rainfall, evaporation and proximity to freshwater Figure 1. The Indian River lagoon system, Florida. runoff sources or the inlets, but averages 25.6 ppt annually. Open lagoon waters may become hypersaline, with concentrations as high as 42 ppt. Surface temperatures average 11 °C in winter and 31 °C in summer. The lowest recorded water temperature was 6 °C from a lagoon in northern Brevard County (Snelson and Bradley 1978). Several small, low gradient rivers, creeks and canals flow into this system. The largest drainage area is the

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Dawn P. Jennings

Papers

Asian Carps of the Genus Hypophthalmichthys (Pisces, Cyprinidae) ― A Biological Synopsis and Environmental Risk Assessment

How much is enough? Landscape-scale conservation for the Florida panther

Behavioral aspects of cold tolerance in blackchin tilapia, Sarotherodon melanotheron, at different salinities

Factors Influencing the Distribution of Blackchin Tilapia Sarotherodon melanotherodon (Osteichthyes: Cichlidae) in the Indian River System, Florida