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We evaluated the crustacean zooplankton size spectrum as an indicator of lake characteristics and ecosystem change. First, we used time series from seven Canadian Shield lakes to identify the factors associated with among-lake and among-year variability in the spectrum slope (relative abundance of small and large zooplankton) and centered height (total abundance). Second, we used time series from an invaded and three control lakes to assess change in mean and variability in slope and height due to a Bythotrephes invasion. We found that the slope and height reflected among-lake predictors related to morphometry. The slope was responsive to long-term declining lake phosphorus levels, whereas the height reflected both increases in dissolved organic carbon and decreases in ice duration. We detected a significant increase (i.e., flattening) in mean slope and substantial (up to 120%) increases in the CV of height after Bythotrephes invaded Harp Lake. Thus, the zooplankton size spectrum was responsive to long-term environmental change, and a strong top-down perturbation can be detected through regular and frequent monitoring programs. Nous evaluons le spectre de tailles des crustaces zooplanctoniques a titre d'indicateur de caracteristiques du lac et de changements ecosystemiques. Nous utilisons d'abord des series chronologiques de sept lacs du bouclier canadien pour cerner les facteurs associes a la variabilite interannuelle et entre lacs de la pente (abondance relative du petit et du grand zooplanctons) et de la hauteur centree (abondance totale) des spectres. Nous utilisons en deuxieme lieu des series chronologiques d'un lac envahi et de trois lacs temoins pour evaluer les changements de la moyenne et de la variabilite de la pente et de la hauteur attribuables a un envahissement par Bythotrephes. Nous constatons que la pente et la hauteur refletent des predicteurs de la variance entre lacs associes a la morphometrie. La pente reagit a des baisses a long terme des concentrations de phosphore dans les lacs, alors que la hauteur reflete a la fois des augmentations du carbone organique dissous et des diminutions de la duree de la glace. Nous relevons une augmentation significative (c.-a-d. un aplatissement) de la pente moyenne et des augmentations considerables (jusqu'a 120 %) du CV de la hauteur apres l'envahissement du lac Harp par Bythotrephes. Le spectre de tailles du zooplancton reagit donc a des changements environnementaux a long terme, et une forte perturbation descendante peut etre detectee par des programmes de surveillance reguliere et frequente. [Traduit par la Redaction], Introduction Body size is a key individual trait that varies predictably with many ecological and physiological processes (e.g., metabolic rate, diet breadth, population abundance, somatic growth rate, and life history [...]

Developing the crustacean zooplankton community size spectrum into an indicator of change in lakes requires quantification of the natural variability in the size spectrum related to broad-scale seasonal, annual, and spatial factors. Characterizing seasonal patterns of variation in the size spectrum is necessary so that monitoring programs can be designed to minimize the masking effects that seasonal processes can have on detecting longer-term temporal change. We used a random effects model to measure monthly, annual, and interlake variability in the slope (i.e., relative abundance of small and large organisms) and centered height (i.e., total abundance) of the crustacean zooplankton normalized abundance size spectrum from 1981 to 2011 among eight Canadian Shield lakes. Consistent with theoretical predictions, the slope was a relatively stable characteristic of the zooplankton community compared with the height, which varied significantly among lakes. We identified a seasonal signal in height and slope and used a mixed effects model to characterize the linear rate of change from May to October; there was an overall decline in height and an overall increase in slope. Seasonal variance was greater than annual variance for both the height and the slope, suggesting that long-term monitoring of lakes and interlake comparisons using zooplankton size spectra should be based on temporally standardized sampling protocols that minimize the effects of seasonal processes. We recommend sampling the zooplankton community in midsummer because this results in size spectrum estimates close to seasonal mean values. L'utilisation du spectre de tailles de communautes de zooplancton crustace comme indicateur de changement dans les lacs necessite la quantification de la variabilite naturelle dans le spectre de tailles associee a des facteurs saisonniers, annuels et spatiaux a grande echelle. La caracterisation des motifs saisonniers de variation dans le spectre de tailles est necessaire pour concevoir des programmes de surveillance qui minimisent les effets de masquage que peuvent exercer des processus saisonniers sur la detection de changements a long terme. Nous avons utilise un modele d'effets aleatoires pour mesurer la variabilite mensuelle, annuelle et entre lacs de la pente (c.-a-d. l'abondance relative des organismes de petite et grande taille) et la hauteur centree (c.-a-d. l'abondance totale) du spectre d'abondance selon la taille normalise de zooplancton crustace de 1981 a 2011 pour huit lacs du Bouclier canadien. Conformement aux predictions theoriques, la pente s'avere une caracteristique relativement stable de la communaute de zooplancton comparativement a la hauteur, qui varie significativement entre les lacs. Nous relevons un signal saisonnier dans la hauteur et la pente et utilisons un modele a effets mixtes pour caracteriser le taux lineaire de changement de mai a octobre; il en ressort une baisse globale de la hauteur et une hausse globale de la pente. La variance saisonniere est plus grande que la variance annuelle tant pour la hauteur que pour la pente, donnant a penser que la surveillance a long terme de lacs et les comparaisons entre lacs qui font appel aux spectres de tailles du zooplancton devraient reposer sur des protocoles d'echantillonnage a normalisation temporelle qui minimisent les effets de processus saisonniers. Nous recommandons l'echantillonnage des communautes de zooplancton au milieu de l'ete puisque cela produit des estimations du spectre de tailles s'approchant des valeurs moyennes saisonnieres., Introduction Many indicators have been developed to provide information about the composition, structure, or function of aquatic ecosystems (Great Lakes Water Quality and Science Advisory Boards 2013). However, a key [...]

There is a common misconception among government officials that environmental regulations are bad for economic growth. Citing economic reasons, the Canadian federal government passed legislation in 2012 restricting the length of environmental reviews of new developments, even though review times were not empirically known. Using annual reports to Parliament from 2001 to 2010, we estimated using time-series analyses that review times under the Fisheries Act conformed to the new government mandated review times prior to major legislative changes to federal environmental oversight. The majority of submissions were processed within 1 year for mitigated impacts and within 2 years for authorized impacts. While it is possible that a minority of projects take longer, there is no evidence of large backlogs in the review process, and Canadian review times appear quicker than those in the United States. We highlight the need for empirical estimates of the costs of environmental regulations before governments enact substantial legislative changes that reduce environmental oversight and offer alternate recommendations for expediting environmental review times. Les representants gouvernementaux considerent souvent, a tort, que la reglementation relative a la protection environnementale nuit a la croissance economique. Evoquant des raisons economiques, le gouvernement federal du Canada adoptait, en 2012, une loi qui restreint la duree des examens environnementaux de nouveaux projets et ce, en l'absence de donnees empiriques sur la duree de ces examens. A la lumiere de rapports annuels du Parlement de 2001 a 2010, nous avons estime, a l'aide d'analyses de series chronologiques, que les durees des evaluations environnementales menees envertude la Loi sur les peches etaient conformes aux nouvelles durees prescrites par le gouvernement avant l'entree en vigueur d'importants changements legislatifs relatifs a la surveillance environnementale par le gouvernement federal. La majorite des demandes etait traitee dans l'annee en ce qui concerne les impacts devant etre attenues, et en deca de deux ans pour les impacts autorises. S'il se peut qu'une minorite de projets prenne plus de temps, rien n'indique des retards importants dans le processus d'evaluation, et il semblerait que la duree des evaluations soit moins longue au Canada qu'aux Etats-Unis. Nous soulignons la necessite d'estimations empiriques des couts de la reglementation environnementale prealablement a la promulgation par les gouvernements de modifications legislatives importantes qui limitent la surveillance environnementale et nous proposons d'autres moyens permettant de reduire la duree des evaluations environnementales. [Traduit par la Redaction], Introduction Last year, the Canadian and United States federal governments passed executive orders, budget legislation, and policy changes with the goal of expediting environmental review times for industrial, commercial, and [...]

The current state of many freshwater fish stocks worldwide is largely unknown but suspected to be vulnerable to exploitation from recreational fisheries and habitat degradation. Both these factors, combined with complex ecological dynamics and the diffuse nature of inland fisheries could lead to an invisible collapse: the drastic decline in fish stocks without great public or management awareness. In this study we provide a method to address the pervasive knowledge gaps in regional rates of exploitation and habitat degradation, and demonstrate its use in one of North America’s largest and most diffuse recreational freshwater fisheries (Ontario, Canada). We estimated that 1) fish stocks were highly exploited and in apparent danger of collapse in management zones close to large population centres, and 2) fish habitat was under a low but constant threat of degradation at rates comparable to deforestation in Ontario and throughout Canada. These findings confirm some commonly held, but difficult to quantify, beliefs in inland fisheries management but also provide some further insights including 1) large anthropogenic projects greater than one hectare could contribute much more to fish habitat loss on an area basis than the cumulative effect of smaller projects within one year, 2) hooking mortality from catch-and-release fisheries is likely a greater source of mortality than the harvest itself, and 3) in most northern management zones over 50% of the fisheries resources are not yet accessible to anglers. While this model primarily provides a framework to prioritize management decisions and further targeted stock assessments, we note that our regional estimates of fisheries productivity and exploitation were similar to broadscale monitoring efforts by the Province of Ontario. We discuss the policy implications from our results and extending the model to other jurisdictions and countries. [ABSTRACT FROM AUTHOR]