Gilbert Cabana - Profile on Academia.edu (original) (raw)

Papers by Gilbert Cabana

Interannual variability in stage-specific survival rates and the causes of recruitment variation

Early Life History and Recruitment in Fish Populations, 1997

Primates, 1990

The effects of mean troop size, diet, territoriality, and habitat upon temporal variability of gr... more The effects of mean troop size, diet, territoriality, and habitat upon temporal variability of group size in primates were investigated using variance functions relating mean group size and temporal variability. Two different types of variability were described: (1) within group variability where a single troop was followed over a given period of time; and (2) between group variability where the

Does δ 15N in river food webs reflect the intensity and origin of N loads from the watershed?

Science of The Total Environment, 2006

Stable nitrogen isotope ratios (δ15N) were measured in invertebrates and fish collected from 82 r... more Stable nitrogen isotope ratios (δ15N) were measured in invertebrates and fish collected from 82 river sites located in the Saint-Lawrence Lowlands in Québec, Canada, to examine the relationship between aquatic biota δ15N and anthropogenic nitrogen (N) loads. Mean δ15N values of all three trophic levels examined (primary consumers, predatory invertebrates and invertebrate-feeding fish) were highly correlated with total anthropogenic N

Estimating the trophic position of aquatic consumers in river food webs using stable nitrogen isotopes

Journal of The North American Benthological Society, 2007

Intraspecific and interspecific variation in the trophic position of various consumers is central... more Intraspecific and interspecific variation in the trophic position of various consumers is central to many theories of aquatic ecosystem functioning and dynamics. In recent years, such issues have been addressed using stable N isotopes (δ 15 N) to estimate trophic position of ...

δ 15 N in riverine food webs: effects of N inputs from agricultural watersheds

Canadian Journal of Fisheries and Aquatic Sciences, 2005

Abstract: We examined the use of the natural abundance of nitrogen stable isotopes (δ15N) as a tr... more Abstract: We examined the use of the natural abundance of nitrogen stable isotopes (δ15N) as a tracer of anthropo-genic perturbations of the nitrogen (N) cycle at the watershed scale in 82 river sites draining 13 watersheds in the St. Lawrence Lowlands in Quebec. Mean δ15N ...

Limnology and Oceanography, 1999

We used variation in algal d 13 C between river habitats to study the spatial scale of energy flo... more We used variation in algal d 13 C between river habitats to study the spatial scale of energy flow through river food webs. We found a strong negative relationship between herbivore d 13 C (which reflects algal d 13 C) and water velocity in three productive Northern California rivers but not in unproductive streams. The contrast among habitats suggests that

Comparison of aquatic food chains using nitrogen isotopes

Proceedings of the National Academy of Sciences, 1996

Recent studies have shown the utility of delta(15)N to model trophic structure and contaminant bi... more Recent studies have shown the utility of delta(15)N to model trophic structure and contaminant bioaccumulation in aquatic food webs. However, cross-system comparisons in delta(15)N can be complicated by differences in delta(15)N at the base of the food chain. Such baseline variation in delta(15)N is difficult to resolve using plankton because of the large temporal variability in the delta(15)N of small organisms that have fast nitrogen turnover. Comparisons using large primary consumers, which have stable tissue isotopic signatures because of their slower nitrogen turnover, show that delta(15)N increases markedly with the human population density in the lake watershed. This shift in delta(15)N likely reflects the high delta(15)N of human sewage. Correcting for this baseline variation in delta(15)N, we report that, contrary to expectations based on previous food-web analysis, the food chains leading up to fish varied by about only one trophic level among the 40 lakes studied. Our results also suggest that the delta(15)N signatures of nitrogen at the base of the food chain will provide a useful tool in the assessment of anthropogenic nutrient inputs.

Anthropogenic alterations of lotic food web structure: evidence from the use of nitrogen isotopes

Oikos, 2009

Understanding the processes that regulate food chain length in nature is a classic theme in ecolo... more Understanding the processes that regulate food chain length in nature is a classic theme in ecology. Two factors expected to explain variation in food chain length are resource availability (productivity) and environmental stress. We examined the impact of ...

Measuring life-history omnivory in the opossum shrimp, Mysis relicta, with stable nitrogen isotopes

Limnology and Oceanography, 2000

... Biology McGill University 1205 Docteur Penfield Montreal, Quebec H3A lB 1 Asit Mazumder Depar... more ... Biology McGill University 1205 Docteur Penfield Montreal, Quebec H3A lB 1 Asit Mazumder Departement de Sciences biologiques Universite de Montreal CP 6128, Succursale A Montreal, Quebec H3C 3J7 Joseph B. Rasmussen ... EVANS, M. S., RW BATHELT, AND C. P. RICE. ...

Feeding by black fly (Diptera:Simuliidae) larvae causes downstream losses in phytoplankton, but not bacteria

Journal of the North American Benthological Society, 2004

Estimating the feeding range of a mobile consumer in a river-flood plain system using δ13C gradients and parasites

Journal of Animal Ecology, 2011

1. The feeding range of an individual is central to food web dynamics as it determines the spatia... more 1. The feeding range of an individual is central to food web dynamics as it determines the spatial scale of predator-prey interactions. However, despite recognition of its importance as a driving force in population dynamics, establishing feeding range is seldom done as detailed information on trophic interactions is difficult to obtain. 2. Biological markers are useful to answer this challenge as long as spatial heterogeneity in signal is present within the area investigated. A spatially complex ecosystem, Lake St. Pierre (LSP), a fluvial lake of the St Lawrence River (Québec, Canada), offered a unique opportunity to determine the feeding range of a secondary consumer, yellow perch (Perca flavescens) using isotopic ratios of carbon (δ(13)C). However, because food chains based on phytoplankton have generally more negative δ(13) C than those depending on periphyton, it was essential to determine the contribution of zooplankton in fish diet to correctly interpret spatial patterns of δ(13)C. We used parasites in perch to examine whether their δ(13)C was reflecting local δ(13)C baseline conditions rather than a feeding specialization on zooplankton. 3. δ(13)C of primary consumers was highly variable and exhibited a striking gradient along the shore-channel axis, suggesting that δ(13)C should reflect an individual consumer&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;s spatial position in LSP. 4. This strong isotopic gradient allowed us to estimate the spatial scale of the resources used by individual perch following an approach presented by Rasmussen, Trudeau &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp; Morinville (Journal of Animal Ecology, 78, 2009, 674). By comparing the δ(13)C variability in perch to that of primary consumers, we estimated that the adults feeding range was around 2 km along the shore-channel axis. 5. The combined use of isotopic ratios and parasites allowed us to determine that the adult population uses a wide range of habitats between the flood plain and the main channel. However, individually, each perch depended on a limited foodshed.

Freshwater Biology, 2009

1. Stable isotopes of carbon are useful for differentiating between freshwater food chains based ... more 1. Stable isotopes of carbon are useful for differentiating between freshwater food chains based on planktonic algae or benthic algae, but are reported to be of limited use for identifying food chains based on sedimentary detritus. Because data from marine systems suggest that stable isotopes of sulphur (d 34 S values) have potential in this regard, we tested their utility in freshwater lakes. 2. We found that sulphate in the water column of four boreal lakes was enriched in 34 S compared to the sulphur in bulk sediments from these lakes. Furthermore, within a given lake, insects known to feed on sediment (directly or via predation) had d 34 S values similar to those of sediment, whereas planktonic and benthic invertebrates known to feed on suspended particles had d 34 S values similar to those of sulphate in the water column. 3. Using the stable S isotope values of invertebrates that obtain their S from either the sediment or the water column as end members in a two-source mixing model, we show that two fish species obtain their food from both planktonic and sedimentary sources. Furthermore, model results suggest that, as expected, the more benthic-feeding fish species obtains more of its S from the sediment compartment than does the species that feeds in the water-column. 4. Our results suggest that measurements of stable sulphur isotopes provide a means of distinguishing between members of food chains that are based in the water column from those based on sedimentary detritus. As such, they would be a useful complement to stable C isotopes that are used to distinguish between food chains based on planktonic or benthic algae.

Are diatoms good integrators of temporal variability in stream water quality?

Freshwater Biology, 2008

Estuaries and Coasts, 2011

Tomcod (Microgadus tomcod) in the St. Lawrence estuarine transition zone (ETZ) undergo an ontogen... more Tomcod (Microgadus tomcod) in the St. Lawrence estuarine transition zone (ETZ) undergo an ontogenetic habitat shift. Older age classes, characterised by a maledominated sex ratio, disperse downstream over the summer months to occupy the colder more saline waters of the estuary. Significant differences in length and mass along the salinity gradient were observed in September with upstream fish of any given age class generally exhibiting greater growth. These differences were not seen in early summer. Benthic amphipod δ 34 S signatures were strongly correlated with salinity and served to demonstrate that tomcod δ 34 S signatures were not in isotopic equilibrium in the more saline waters of the ETZ. Seasonal distributional patterns, growth dynamics and isotopic disequilibrium all indicate that the observed habitat shift may occur on an annual basis, following winter aggregation in warmer, less saline waters. Tomcod located in the downstream parts of the ETZ, predominantly males, were significantly more sexually developed than upstream tomcod for a given age. On the other hand, greater growth early in life is insured by occupying warmer, upstream waters during the summer months.

An evaluation of the success of dredging as remediation at a DDT-contaminated site in San Francisco Bay, California, USA

Environmental Toxicology and Chemistry, 2002

Lauritzen Canal, a portion of San Francisco Bay near Richmond, California, USA, was heavily conta... more Lauritzen Canal, a portion of San Francisco Bay near Richmond, California, USA, was heavily contaminated with dichlorodiphenyltrichloroethane (DDT) and dieldrin as a result of releases from a pesticide-formulating firm. In 1996 and 1997, 82,000 m3 of contaminated sediment was removed from the canal by dredging. This study evaluated the success of the dredging based largely on body burdens of DDT and its metabolites (sigmaDDT) in resident biota, with some data on sediment- and water-contaminant levels and sediment toxicity testing. Sediment disturbance during dredging introduced a pulse of sigmaDDT into the Lauritzen Canal ecosystem, and body burdens of fish and invertebrates increased 2- to 76-fold, depending on the species. Approximately 1 1/2 years after remediation, 11 of 14 indicators showed contamination comparable with or worse than the contamination that existed prior to dredging. Monitoring of mussels up to four years postdredging suggests some modest improvement, although the sigmaDDT body burden of canal mussels remained far above the norm for San Francisco Bay. The elevated sigmaDDT body burdens in biota that persisted for years after remediation reflect recent exposure and are not merely a result of slow metabolic elimination of the sigmaDDT pulse associated with dredging. Sediment sigmaDDT concentrations were low immediately after dredging, but within months, the canal bottom became covered with a veneer of fine sediment as contaminated as that that had been removed. The source of this material has not been conclusively established, but we suspect it came from slumping and erosion from the flanks of the canal beneath docks and around pilings where dredging was not done. In retrospect, either capping in place or more thorough dredging may have been more successful in reducing pesticide exposure of the biota, although there were difficulties associated with both alternatives.

Canadian Journal of Fisheries and Aquatic Sciences, 1997

Stable nitrogen isotope ratios (δ 15 N) are commonly used to represent the trophic structure of a... more Stable nitrogen isotope ratios (δ 15 N) are commonly used to represent the trophic structure of aquatic systems, yet the ability of δ 15 N to indicate the trophic position of aquatic consumers remains untested using traditional dietary methods. Interpreting the δ 15 N of aquatic consumers relative to large, long-lived primary consumers such as unionid mussels provides a continuous measure of an organism's trophic position that adjusts for among-system variation in baseline δ 15 N. We used this method to estimate the trophic position of eight littoral fish species from 36 lakes in Ontario and Quebec. We validated these δ 15 N measures of trophic position by compiling literature dietary data from 342 populations of these same fish species and calculated a continuous measure of trophic position for each population. Mean dietary trophic position estimates corresponded closely to 15 N estimates, with mean trophic position ranging from 3.3 for pumpkinseed (Lepomis gobbosus) to 4.4 for walleye (Stizostedion vitreum). Both methods indicated approximately one trophic level of variation among populations of a species. This study confirms the ability of baseline-adjusted δ 15 N to represent the trophic position of aquatic consumers.

Canadian Journal of Fisheries and Aquatic Sciences, 1994

PeerJ, 2015

Environmental homogenization in coastal ecosystems impacted by human activities may be an importa... more Environmental homogenization in coastal ecosystems impacted by human activities may be an important factor explaining the observed decline in fish species richness. We used fish community data (>200 species) from extensive surveys conducted in two biogeographic provinces (extent >1,000 km) in North America to quantify the relationship between fish species richness and local (grain <10 km(2)) environmental heterogeneity. Our analyses are based on samples collected at nearly 800 stations over a period of five years. We demonstrate that fish species richness in coastal ecosystems is associated locally with the spatial heterogeneity of environmental variables but not with their magnitude. The observed effect of heterogeneity on species richness was substantially greater than that generated by simulations from a random placement model of community assembly, indicating that the observed relationship is unlikely to arise from veil or sampling effects. Our results suggest that rest...