Long-term habitat changes in a protected area: Implications for herpetofauna habitat management and restoration

Point Pelee National Park, located at the southern-most tip of Canada's mainland, historically supported a large number of herpetofauna species; however, despite nearly a century of protection, six snake and five amphibian species have disappeared, and remaining species-At-risk populations are thought to be in decline. We hypothesized that long-Term changes in availability and distribution of critical habitat types may have contributed to the disappearance of herpetofauna. To track habitat changes we used aerial image data spanning 85 years (1931±2015) and manually digitized and classified image data using a standardized framework. Change-detection analyses were used to evaluate the relative importance of proportionate loss and fragmentation of 17 habitat types. Marsh habitat diversity and aquatic connectivity has declined since 1931. The marsh matrix transitioned from a graminoid and forb shallow marsh interspersed with water to a cattail dominated marsh, altering critical breeding, foraging, and overwintering habitat. Reduced diversity of marsh habitats appears to be linked to the expansion of invasive Phragmites australis, which invaded prior to 2000. Loss of open habitats such as savanna and meadow has reduced availability of high quality thermoregulation habitat for reptiles. Restoration of the northwestern region and tip of Point Pelee National Park to a mixed landscape of shallow wetlands (cattail, graminoid, forb, open water) and eradication of dense Phragmites stands should improve habitat diversity. Our results suggest that long-Term landscape changes resulting from habitat succession and invasive species can negatively affect habitat suitability for herpetofauna and protection of land alone does not necessarily equate to protection of sensitive herpetofauna

An Empirical Model to Predict in situ Grazing Rates of Diaptomus minutus Lilljeborg on Small Algal Particles

An empirical model constructed to predict grazing rate as a function of the relative proportion of small (<10mu m) to large (10-30mu m) algal particles in the nanoplankton accurately predicted diaptomid grazing rates for 3 lakes in an independent lake set; but produced overestimates for 2 other lakes. There was also a significant positive correlation between grazing rate and the biomass concentration of small algae in the lakes. -from Autho

Seasonal, Interannual, and Spatial Variability in the Concentrations of Total Suspended Solids in a Degraded Coastal Wetland of Lake Ontario

A 4-year (1993 through 1996) monitoring program examined the distribution of total suspended solids (TSS) in Cootes Paradise Marsh, a shallow (mean depth of 70 cm), degraded, drowned-rivermouth marsh of Lake Ontario. Monthly meteorological and hydrographical data from 1986 through 1996 revealed a hydrologically dynamic system that exhibited large seasonal and interannual variation with respect to precipitation amount, discharge volume, and water levels; the prevailing winds were shown to be oriented along the length of the marsh. Interannual variation in TSS concentrations was inversely related to mean seasonal water levels that fluctuated 45 cm over the 11 years. In a stepwise regression analysis, planktonic chlorophyll-a concentration only explained 2% of the variation in TSS, while inorganic and non-algal organic solids explained 70% and 18%, respectively. Mean seasonal water turbidity increased significantly with mean seasonal wind speed at 17 sampling stations during 1993 and 1994. Runoff from a summer rainstorm more than doubled water turbidities at the mouth of all three creeks over the first 36 hours. In enclosure experiments, water turbidity increased proportionately with biomass of benthivorous fish (especially common carp, Cyprinus carpio). When wind and carp disturbance were compared simultaneously in the field, wind speed accounted for 41% of the variation in turbidity while presence of carp explained an additional 21%. The overall temporal and spatial distribution of TSS in the marsh reflected changes in water level, wind activities, onset of rain events, and fish disturbance that acted in concert to keep Cootes Paradise Marsh extremely turbid throughout the summer

Ecosystem response to changes in water level of Lake Ontario marshes: lessons from the restoration of Cootes Paradise Marsh

A general understanding of how aquatic vegetation responds to water-level fluctuations is needed to guide restoration of Great Lakes coastal wetlands because inter-annual and seasonal variations often confound effects of costly remedial actions. In 1997, common carp (Cyprinus carpio) was removed from Cootes Paradise Marsh (L. Ontario) to reduce sediment resuspension and bioturbation, and thus regenerate marsh plants that had declined dramatically since the 1930s. Data from 1934 to 1993 were re-assembled from the literature to relate percentage cover of emergent vegetation to mean summer water level. A non-linear regression equation explained close to 90% of the variation compared with 80% for a non-linear equation, and this trend was confirmed for the dominant species, Typha latifolia. A modest recovery of emergent vegetation in 1999 following carp exclusion could have been predicted from declining water level alone, without invoking any effects of the biomanipulation. An unusually cool spring in 1997 delayed the migration of spawning planktivores into the marsh. This resulted in a grazer-mediated clear-water phase that coincided with a resurgence of the submersed aquatic vegetation (SAV) community in 1997, which declined again in 1999 when low water levels occurred. Even though decrease in water level was significantly related to increased suspended solids and greater light attenuation, light conditions appeared to have been adequate in marsh embayments to support SAV growth, according to a published relationship between maximum depth of SAV colonization and light extinction coefficient. I suggest that wave disturbance and propagule burial associated with shallow water depths may have been the main reasons for the decline of the SAV in 1999 and 2000. © Springer 2005

A conceptual ecological model to aid restoration of Cootes Paradise Marsh, a degraded coastal wetland of Lake Ontario, Canada

An ecological model is derived from recent studies, based on 60 years of empirical observations and experimental data, that conceptualizes how Cootes Paradise Marsh was transformed from a lush emergent marsh with considerable ecological diversity in all trophic levels, to one that is currently turbid, devoid of vegetation, and dominated by a few exotic plant and fish species. This conceptual model contains 17 key components that interact and contribute to the overall unhealthy state of the marsh. The most influential component is high water level which caused the initial loss of emergent vegetation in the 1940s and 1950s. In the absence of plants to attenuate sediment and assimilate nutrients, the marsh became turbid and windswept, and this led to the disappearance of submergent vegetation over the next two decades. Currently, high water turbidity is being maintained by wind re-suspension, high sediment loading from the watershed during the summer, high algal biomass resulting from excessive nutrient loads from sewage effluent and surface runoff, and the feeding and spawning activities of a very large population of common carp (Cyprinus carpio). Due to vegetation loss, the substrate has become mostly loose sediment that is no longer suitable for the diverse assemblage of aquatic insect larvae that lived on the plants and detrital material in the 1940s. Benthic grazers have been kept in low abundances due to predation by benthivorous carp; consequently, epiphytic algae have proliferated and further contribute to light limitation of macrophytes. High nutrient loadings contribute to high diurnal fluxes in dissolved oxygen levels that tend to select against less tolerant organisms such as insect larvae (other than chironomids) and piscivores (northern pike and largemouth bass). Without piscivores in the marsh, the planktivores have become dominant and have virtually eliminated all of the large herbivorous zooplankton (e.g., Daphnia), except for a few pockets in the marsh inlets close to residual macrophyte beds. Because of the dominance of small-bodied inefficient grazers (rotifers and small cladocerans), algal biomass is high, and the community has a large proportion of heterotrophic forms that tolerate low light environments. This ecological model suggests that the current turbid un-vegetated state of Cootes Paradise may be very stable. It will persist as long as water levels remain unfavorable for natural re-colonization by the emergent flora, and/or water turbidities remain sufficiently high to suppress the growth of submergent vegetation. Using this conceptual model, I developed a model of how Cootes Paradise Marsh may have functioned as a healthy marsh prior to the 1940s, and use these models as a basis to explore a number of restoration and management options and discuss their implications on the aquatic foodweb

Effect of collection and acclimation period on grazing rates of limnetic zooplankton

Grazing rates of Daphnia sp. and Diaptomus oregonensis measured using an in situ method (Haney 1971) were compared with rates measured by collecting animals in vertical townets and placing them in experimental chambers either immediately or after a 24-h acclimation period. Experiments with acclimation yielded grazing rates of Daphnia that were statistically higher than in situ rates, whereas experiments conducted without acclimation yielded significantly lower rates. In situ grazing rates of Diaptomus were statistically higher than those for both townet techniques; experiments without an acclimation yielded higher rates than those for experiments with a 24-h acclimation period. © 1986 Dr W. Junk Publishers

A versatile gene trap to visualize and interrogate the function of the vertebrate proteome

We report a multifunctional gene-trapping approach, which generates full-length Citrine fusions with endogenous proteins and conditional mutants from a single integration event of the FlipTrap vector. We identified 170 FlipTrap zebrafish lines with diverse tissue-specific expression patterns and distinct subcellular localizations of fusion proteins generated by the integration of an internal citrine exon. Cre-mediated conditional mutagenesis is enabled by heterotypic lox sites that delete Citrine and “flip” in its place mCherry with a polyadenylation signal, resulting in a truncated fusion protein. Inducing recombination with Cerulean-Cre results in fusion proteins that often mislocalize, exhibit mutant phenotypes, and dramatically knock down wild-type transcript levels. FRT sites in the vector enable targeted genetic manipulation of the trapped loci in the presence of Flp recombinase. Thus, the FlipTrap captures the functional proteome, enabling the visualization of full-length fluorescent fusion proteins and interrogation of function by conditional mutagenesis and targeted genetic manipulation

Impacts of declining water levels on the quantity of fish habitat in coastal wetlands of eastern Georgian Bay, Lake Huron

There are >3,700 coastal wetlands along 4,500 km of eastern Georgian Bay (GB), providing critical spawning and nursery habitat for migratory fish of Lake Huron. Sustained low water levels since 1999 have led to the loss of fish habitat due to severance of wetlands from GB. We estimate (1) the amount of fish habitat that has already been lost between the historic high water level (177. 5 m asl) and current levels (176. 11 m asl) using a site-specific approach for seven wetlands and (2) the magnitude of loss if water levels were to decrease as predicted by global circulation models (GCMs) using a regional method that is applicable to all of eastern and northern GB. Maximum depth of wetland outlets (162. 94-176. 06 m asl) was used to estimate the cumulative area of habitat that would become hydrologically disconnected as water levels decline. If water levels were to drop to 175. 33 m asl, as predicted by one GCM, 13% of the total number of coastal wetlands and 6% of the total area in coastal wetlands would disappear in addition to what has already been lost. For both the methods, the rate of habitat loss was greatest between 173 and 176 m asl. © 2012 Springer Science+Business Media B.V

Use of IKONOS Imagery to Map Coastal Wetlands of Georgian Bay

Wetlands throughout North America have been diminished in quantity and quality because of human activities, and it is therefore important that fishery managers monitor changes in supply of this critical fish habitat. Use of traditional field-based methods to detect and record the change in aquatic vegetation in Great Lakes wetlands is a daunting task because wetlands are extensive and widely distributed along the Great Lakes shoreline. Mapping wetlands for such a large geographic area necessitates the use of remote sensing technology to obtain an accurate inventory of these ecosystems. The objective of this study was to explore the capabilities of using IKONOS satellite imagery to map different types of aquatic vegetation and habitat features in Great Lakes wetlands. We acquired imageries for Fathom Five National Marine Park in Lake Huron and an area of eastern Georgian Bay in 2002 and chose 11 wetlands for habitat mapping with remote sensing software. The comparison of results of the image analysis with reference data indicated that the overall accuracy of mapping was approximately 90%. This suggests that high resolution IKONOS imagery can be used effectively to monitor the change in aquatic vegetation and thus track alterations in fish habitat in Great Lakes coastal marshes