Jean-Luc DesGranges

HINDLIMB DEFORMITIES (ECTROMELIA, ECTRODACTYLY) IN FREE-LIVING ANURANS FROM AGRICULTURAL HABITATS

High prevalences of hindlimb deformities were recorded in wild-caught green frogs (Rana clamitans), northern leopard frogs (Rana pipiens), American toads (Bufo americanus), and bullfrogs (Rana catesbeiana) from agricultural sites exposed to pesticide runoff in the St. Lawrence River Valley of Québec, Canada, between July and September 1992 and 1993. Of 853 metamorphosing anurans examined in 14 farmland habitats, 106 (12%; range 0 to 69%) had severe degrees of ectromelia and ectrodactyly, compared to only two (0.7%; range 0 to 7.7%) of 271 in 12 control sites. However, the variation in the proportion of deformities among sites was too large to conclude that there was a significant difference between control and pesticide-exposed habitats. Clinical signs varied and were characterized by segmental hypoplasia or agenesis of affected limbs. Conspicuous abnormalities interfered with swimming and hopping, and likely constituted a survival handicap. Because of circumstances and the frequency of these malformations in nine distinct habitats, and in three different species from one of our study sites, we propose a teratogenic action of exogenous factors. Despite the fact that many biotic and abiotic agents are potentially harmful to limb development, agricultural contaminants were suspected as primary aggressors. Thus, clinical examination and frequency of deformities in anurans might be an economical screening tool to assess ecosystem health and the presence of environmental contaminants.

EFFECTS OF AGRICULTURAL PRACTICES ON THE FLORA OF HEDGEROWS AND WOODLAND EDGES IN SOUTHERN QUEBEC

The structure and distribution of herbaceous species were examined in cultivated fields and in adjacent habitats in light of herbicide use and tillage. The diversity and vegetation cover of the herbaceous layer of hedgerows and woodland edges were lower on sites at which herbicides had been sprayed in recent years, probably due to herbicide drift during application on adjacent fields. Herbicide use and tillage had an impact on the species composition of the cultivated fields: there was a higher proportion of annual and introduced species in cultivated fields subjected to herbicide use and tillage than in fields that were not regularly treated or tilled. The species that were found only in non-crop habitats were primarily native and perennials, few of which were weed species, whereas a high proportion of the species found only in cultivated fields were annual and introduced species, several of which were considered weeds. Key words: Woodland edge, hedgerow, herbicide, tillage, weeds, life span

Population trends in selected species of farmland birds in relation to recent developments in agriculture in the St. Lawrence Valley

Abstract Changes in the populations of 28 species of birds typical of farmland habitats were assessed using data from seven Breeding Bird Survey (BBS) routes surveyed in southern Quebec over the last 25 years. Aerial photographs taken in the 1960s and 1980s covering 82 stops along these routes were interpreted to evaluate changes in the rural landscape. Based on the crops grown at these stops in 1992, four types of agricultural landscapes were identified: cash crops, forage crops and pastureland, crops and livestock raising, and heterogeneous landscape. An intensive bird census of these stops in June 1992 showed that species richness and abundance are greater at stops with a heterogeneous landscape than at those characterized mainly by cash crops. Cash crops (corn, wheat, soybean) now cover more surface area than in the 1960s, whereas numerous dairy farms have disappeared over the past 25 years because of abandonment, urbanization and industrialization. These changes in the crops grown in the most productive agricultural regions of Quebec appear to be responsible for fluctuations in populations of a number of farmland species in the St. Lawrence Lowland. Many species associated with dairy farming, such as the Savannah Sparrow, Bobolink, Brown-headed Cowbird and Eastern Meadowlark, show decreasing population abundance, while other species such as the Ring-billed Gull and Rock Dove appear to be benefiting from the introduction of intensive agriculture.

Changes in breeding bird richness and abundance in Montreal parks over a period of 15 years

We compared the breeding bird population and vegetation structure of 201 randomly selected 1 ha plots in 49 urban parks in Montreal, 15 years apart (in 1979‐1981 and 1994). The constancy of 17 bird species increased significantly, while that of four others decreased. Increased large-tree cover and a reduction in shrub cover do not explain more than a small proportion of this variation in species constancy. We contend that the installation of bird feeder stations in and around parks goes a long way toward explaining these changes, although the recent arrival in Quebec of the House Finch (Carpodacus mexicanus) and the Northern Cardinal (Cardinalis cardinalis) has definitely played a major role in the changes of the bird assemblage. # 1999 Elsevier Science B.V. All rights reserved.

Assessment of Contamination and Biomarker Responses in Two Species of Herons on the St. Lawrence River

This study was undertaken to validate potential biomarkers of exposure and effects due to chemical contaminants in breedingcolonies of the Great Blue Heron and the Black-crowned Night-Heron on the St. Lawrence River. Eggs and fledglings from both species were collected from many colonies along theRiver. The fledglings from colonies in freshwater and brackishwater were more contaminated by mercury and PCBs than those from estuarine and gulf colonies. With respect to fledglings ofthe two heron species, some morphometric and blood biochemicalmeasurements, including plasma thyroid hormones and retinol, were significantly different among colonies. Significant differences were also observed in liver retinoids, EROD and porphyrins among colonies. The results of this study suggestthat plasma retinoids and thyroid hormones are good biomarkersof exposure and effects, and are sufficiently sensitive to reflect local and regional variations in contamination. Along with the measure of contaminants in egg and plasma, they constitute non-invasive biomarkers which represent an importantcriteria for long term monitoring of wildlife species. It is concluded that the Great Blue Heron is an appropriate sentinelspecies in the surveillance network for the St. Lawrence River.

Correspondence between bird and plant hotspots of the St Lawrence river and influence of scale on their location

Various approaches can be adopted for selecting reserves to protect the species of a given territory. The strategies outlined in this study for protecting breeding birds and rare plants associated with the St Lawrence River are based on the concept of hotspots for species richness and rarity. These hotspots (100 km2 squares) were defined separately for vascular plants and birds. Limited data on vascular plants allowed us to designate only rarity hotspots at the coarse-mesh level of the St Lawrence as a whole, while the more extensive data available on birds allowed for a definition of richness and rarity hotspots at three geographical levels of analysis. Bird hotspots, whether defined on the basis of species richness or the presence of rare species, were generally home to over 80% of bird species. Bird rarity hotspots are home to a significantly greater number of rare species than bird richness hotspots, although the latter support more rare species than ordinary squares. Moreover, rarity hotspots for birds did not correlate with rarity hotspots for plants, and the number of rare species of one group found in the hotspots for rare species of the other group is comparable to the number found in other squares. Our results show that to maintain the populations of a large proportion of bird species inhabiting the various ecosystems of the St Lawrence, protected areas should be selected on the basis of analyses carried out at the section or regional level, with the greatest conservation priority on sites with a large number of rare species at these levels of analysis. Indeed, the number of squares required to represent all riverine birds is proportional to the number of rare species. Bird rarity hotspots can serve as a guideline to pinpoint priority areas where more detailed investigation may permit the establishment of meaningful protected areas for riverine birds, particularly in the Gulf of St Lawrence.

Duckling response to changes in the trophic web of acidified lakes

We reared American Black Duck (Anas rubripes Brewster) and Common Goldeneye (Bucephala clangula Linnaeus) ducklings on two Quebec laurentian lakes in which we manipulated brook trout populations (Salvelinus fontinalis Mitchill), lake acidity and lake productivity to relate waterfowl foraging to trophic status of lakes. We developed a preliminary model to assess the effects of lake acidity and productivity,fish predation and interspecific fish/duck competition in relation to available food (aquatic invertebrates).We then validated the model using a factorial analysis of the relationships between the variables pertaining to the diet of the fish and ducklings, and the environmental characteristics of the lakes (acidity, biological production and fish predation).

Exploratory multiscale analysis of the fish assemblages and habitats of the lower St. Lawrence River, Québec, Canada

Abstract.This work presents a multiscale analysis of the fish diversity of the lower St. Lawrence River which flows from the Laurentian Great Lakes of North America. A database of about 14,000 fish sampling stations from the lower St. Lawrence is linked to five different habitat maps of the study area: hydrographical units, water masses, depth, sediment type and wetland type. We hypothesize that species turnover (beta diversity) will be significant among these habitat maps. For each map, we calculate a UPGMA dendrogram based on the Jaccard coefficient of similarity in species occurrences as a first assemblage–habitat model. A randomization test is then used to identify the significant dendrograms from which we infer fish assemblages. We then show that many species are actually selecting or avoiding habitats. Finally, species selecting particular habitats are described by some selected ecological traits that are expected to occur frequently in those habitats. We found assemblages for the hydrographical units but not for the water masses. The fluvial section is selected by many stenohaline and some euryhaline species, while the freshwater estuary and the brackish estuary are only selected by euryhaline species. In the fluvial section at the hydrographical unit scale, many species associated with lentic habitats are limnophilic and more vegetation-dependent while many species selecting lotic habitats are rheophilic insectivorous species. Significant assemblages are defined for depth, sediment type and wetland type. Taken together, we found strong empirical evidence of a diverse actively selecting littoral assemblage of small, low mobility fishes opposing a channel assemblage of larger, more mobile fishes.

Reproduction of American robin (Turdus migratorius) in a suburban environment

We compared the breeding biology of the American robin in a suburban population and in populations from less urbanized environments using data from 141 nests from a dense suburb near Montreal, Que., and data from the literature. Our data suggest that robins potentially can have a large clutch size and very high rates of reproductive success in suburban areas and that the breeding season seems to be longer in suburbs than in more rural settings. In our study area, robins rarely used artificial nesting substrate.

Effects of insecticide use on breeding birds in Christmas tree plantations in Quebec

This research, which was carried out in the spring of 1989 and 1990 in seven balsam fir (Abies balsamea) plantations in southeastern Quebec, examines potential deleterious effects of three insecticides (i.e. dimethoate, diazinon and insecticidal soap) on breeding American Robins (Turdus migratorius) (n=87 nests) and Song Sparrows (Melospizsa melodia) (n=41 nests). Through analyses of blood serum cholinesterases (AChE and BChE) activity both prior to and the second day following applications of the two organophosphorus insecticides, we showed that adult American Robins, Song Sparrows and Chipping Sparrows (Spizella passerina) breeding in the treated plantations were exposed to diazinon and dimethoate (p<0.05). Signs of exposure to diazinon (p<0.05) were also found in young American Robins. However, despite sharp reductions in blood ChE (and, in some cases, marked inhibition confirmed by 2-PAM reactivation), no cases of adult mortality were recorded following the treatments. Cases of complete or partial mortality were recorded in American Robin and Song Sparrow nests, even among control birds (non-exposed birds). No mortality was recorded for broods exposed to the insecticidal soap. Abandonment of nests and egg infertility were ruled out as possible causes of mortality. The cases of total mortality observed in American Robin and Song Sparrow broods exposed to dimethoate were similar to those recorded for control nests (18 and 25% compared to 14 and 21%, respectively). However, among American Robin and Song Sparrow nestlings exposed to diazinon, essentially twice as many cases of total mortality (31 and 38%, respectively) were recorded as for the control nests. It appears that American Robin eggs are sensitive to diazinon and dimethoate, particularly when spraying is carried out early in the incubation stage. In the case of the Song Sparrow, it is mainly the nestlings that succumb after diazinon is sprayed on them or when dimethoate applications are made during the egg stage.