UNIVERSITÉ DU QUÉBEC À MONTRÉAL THE EFFECTS OF BASAL RES OURCE MANIPULATION 0 THE ABUNDANCE AND NUTRITIONAL STATE OF FRESHWATER CRUSTACEAN ZOOPLANKTON MÉMOIRE PRÉSENTÉ COMME EXIGENCE PARTIELLE DE LA MAÎTRISE EN BIOLOGIE PAR ANTHONY MERANTE SEPTEMBRE 2014 UNIVERSITÉ DU QUÉBEC À MONTRÉAL Service des bibliothèques Avertissement La diffusion de ce mémoire se fait dans le respect des droits de son auteur, qui a signé le formulaire Autorisation de reproduire et de diffuser un travail de recherche de cycles supérieurs (SDU-522 - Rév.01-2006). Cette autorisation stipule que «conformément à l'article 11 du Règlement no 8 des études de cycles supérieurs, [l'auteur] concède à l'Université du Québec à Montréal une licence non exclusive d'utilisation et de publication de la totalité ou d'une partie importante de [son] travail de recherche pour des fins pédagogiques et non commerciales. Plus précisément, [l'auteur] autorise l'Université du Québec à Montréal à reproduire, diffuser, prêter, distribuer ou vendre des copies de [son] travail de recherche à des fins non commerciales sur quelque support que ce soit, y compris l'Internet. Cette licence et cette autorisation n'entraînent pas une renonciation de [la] part [de l'auteur] à [ses] droits moraux ni à [ses] droits de propriété intellectuelle. Sauf entente contraire, [l'auteur] conserve la liberté de diffuser et de commercialiser ou non ce travail dont [il] possède un exemplaire., UNIVERSITÉ DU QUÉBEC À MONTRÉAL LES EFFETS DE LA MANIPULATION DES RESSOURCES DE BASE SUR L'ABONDANCE ET L'ÉTAT NUTRITIONNEL DE ZOOPLANCTON CRUSTACÉ MÉMOIRE PRÉSENTÉ COMME EXIGENCE PARTIELLE DE LA MAÎTRISE EN BIOLOGIE PAR ANTHONY MERANTE SEPTEMBRE 2014 ii TABLEUX DES MATIÈRES LISTE DE FIGURES................................................................. 111 LISTE DES TABLEUX............................................................ v RÉSUMÉ (FR) ........................................ ·····............. Vl RÉSUMÉ (A G)................... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Vll CHAPITRE I PROBLÉMATIQUE................................................................... 8 1.1 Introduction to research........................................................... 8 CHAPITRE II L'ARTICLE .................................................................................. 19 2.1 Article . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 2.2 Introduction ................................................................................ 19 2.3 Methods..... ... . . . . . . . . . . . . . . . .. . . . . . .... . . . . . . . . . . . . . . . . . . . . . . . ... . . . . . . . . . . . . . . . . . . . . . . . . 26 2.4 Results ....................................................................................... 33 2.4.1 Physico-chemical conditions ................................................. 33 2.4.2 Basal resources .................................................................. 34 2.4.3 Crustacean zooplank:ton comrmmities ........................................ 39 2.4.4 Crustacean zooplankton nutritional states .................................... 49 2.5 Discussion ..................................................................................... 54 CHAPITRE III CO CLUSION .............................................................................. 62 3.1 Conclusion of research ......................................................... .......... 62 Appendix I . . . . .. . . .. . .... . .. .. .. .. .. . . . .. . .. . .. .. .. . .. . . .. .. . .. . . . .. . .. . .. . . . .. . .. .. .. .. . .. . .. . 66 BIBIOGRAPHIE............................................................................ 68 iii LISTE DES FIGURES Figure De seri ption Page Physico-chemical parameters A) DOC (mean f-lg per L3) ± SE), 8) the light regression coefficient (mean K per m3) ± SE)), C) TP (mean ~--tg per L3) ± SE), and D) TN (mean ppm) ± SE) during week 3 (black) and week 6 (grey) of 37 mesocosms. Water treatments shown only depict those mesocosm with a 6 week lifespan. Results of post-hoc Tukey's test across treatments at week 6 are indicated on figure by letters above bars. Basal resource (A,B) and physcio-chemical (C, D) parameters A) Chi a (mean f-lg per L3) ± SE), 8) BP (mean f-lg C per L3 per day) ± SE), and proxi-parameter to basal resources C) DO (mean %) ± SE), and D) pH (mean ± 2 38 SE), during week 3 (black) and week 6 (grey) of mesocosms. Water treatments shown only depict those mesocosm with a 6 week lifespan. Results of post-hoc Tukey's test across treatments at week 6 are indicated on figure by letters above bars. Basal resource parameter Gross PPr (mean ~--tM02 per hour) ± SE during week 3 (black) and week 6 (grey) of 3 mesocosms. Water treatments shown only depict those 39 mesocosm with a 6 week lifespan. Results of post-hoc Tukey's test across treatments at week 6 are indicated on figure by letters above bars. A) Calanoid copepod (L. minutus) total abundance (mean Log(individuals per m3) ± SE) and 8) calanoid copepod 4 (L. minutus) biomass (mean ~--tg dry weight per m3) ± SE) 43 during week 3 (black) and week 6 (grey) of mesocosms. Results of post-hoc Tukey's test across treatments are indicated on figure by letters above bars A) Cladoceran (D. ambigua, D. longiremis. and . lieder) total abundance (mean Log(individuals per m3) ± SE) and 8) cladoceran (D. ambigua, D. longiremis, and S. lieder) 5 45 biomass (mean fA,g dry weight per m3) ± SE) during week 3 (black) and week 6 (grey) of mesocosms. Results of post-hoc Tukey's test across treatments are indicated on figure by letters above bars. iv A) The cladoceran D. ambigua, B) D. longiremis, and C) 6 S. lieder total abundance (mean Log(individuals per m3) ± 46 SE) during week 3 (black) and week 6 (grey) of mesocosms. Results of post-hoc Tukey's test across treatrnents are indicated on figure by letters above bars. A) Cyclopoid copepod (C. scutifer and A. robustus) total abundance (mean Log(individuals per m3) ± SE) and B) cyclopoid copepod (C. scutifer and A. robustus) biomass 7 48 (mean f-lg dry weight per m3) ± SE) during week 3 (black) and week 6 (grey) of mesocosms. Results of post-hoc Tukey's test across treatments are indicated on figure by letters above bars. A) The cyclopoid copepod C. scutifer and B) A. robustus 8 total abundance (mean Log(individuals per m3) ± SE) 48 during week 3 (black) and week 6 (grey) of mesocosms. Results of post-hoc Tukey's test across treatments are ind icated on figure by letters above bars. N-3 FA (mean± SE; percentage TAG composition) of A) calanoid copepods (L. minutus) and B) cladocerans 9 (D.ambigua, D.longiremis, S. liederi) at week 3 (black) 52 and 6 (grey) of the experiment. Results of post-hoc Tukey's test across treatments are indicated on figure by letters above bars. N-3:n-6 FA ratios (mean ± SE; percentage TAG composition) of A) calanoid copepods (L. minutus) and B) 10 cladocerans (D.ambigua, D.longiremis, S. liederi) at week 53 3 (black) and 6 (grey) of the experiment. Results of post hoc Tukey's test across treatments are indicated on figure by letters above bars. Bacterial FA (mean ± SE; percentage TAG composition) of A) calanoid copepods (L. minutus) and B) cladocerans 11 (D.ambigua, D.longiremis, S. liederi) at week 3 (black) 54 and 6 (grey) of the experiment. Results of post-hoc Tukey's test across treatments are indicated on figure by letters above bars. v LISTE DES TABLEUX Table Description Page Results of factorial ANOV A for mesocosm water treatment physico-chemical and basal resource parameters 36 among mesocosm treatments (n=4). Results of signiticance (p<0.05) are bolded, and results of non sign iticance (p<0.05) are denoted by '-'. Results of factorial ANOV A for crustacean zooplankton community structure and composition among mesocosm treatments (n=4), wherein Shannon-Weiner (S-W) 2 41 diversity index and total abdundace (TA) of the community are presented. Results of signiticance (p<0.05) are bolded, and results of non-signiticance (p>0.05) are denoted by '-'. Results of factorial ANOV A for crustacean zooplankton 3 biomass among mesocosm treatments (n=4). Results of 49 signiticance (p<0.05) are bolded, and results of non sign ificance (p>0.05) are denoted by '-'. Results of factorial ANOV A for crustacean zooplankton FA profile composition (% T AG) among mesocosm 4 50 treatments (n=4). Results of signiticance (p<0.05) are bolded, and results of non-signiticance (p>0.05) are denoted by '-'. Replication of FA samples. Each sample is composed of >800 individuals from a mesocosm water treatment at an 5 51 indicated point of sampling. Replication is equal to number of mesocosms with sufticient animal tissue to perform a laboratory analysis. vi RÉSUMÉ Les lacs d'eau douce subiront une augmentation de matière organique terrestre associée aux changements climatiques dont les effets sur le réseau trophique aquatique sont inconnus. Les profils d'acides gras (AG) peuvent fournir une approche mécanistique pour la compréhension des réponses de la communauté de zooplancton face aux changements environnementaux comme une augmentation de carbone organique dissous (humique) et une augmentation d'éléments nutritifs. Avec l'utilisation de mésocosmes dans un lac des Laurentides (QC), des voies divergentes d'acquisition des ressources par le zooplancton ont été créées favorisant ou défavorisant la consommation d'algues. Une seule communauté de zooplancton a été exposée aux traitements: control, nutriments (azote + phosphore), humique et humique + nutriments. La durée de l'expérience était de 6 semaines, et les variables réponses étaient l'abondance, le biomasse, la diversité et la composition des espèces ainsi que leur profil lipidique des principaux taxons zooplanctoniques. Comparé au traitement ambiant, l'environnement favorisant le phytoplancton (traitement nutriments) a induit une augmentation de l'abondance relative du zooplancton, de la diversité, ainsi que des AG liés à la fécondité. Les traitements humique et humique+ nutriments ont diminué l'abondance, le biomasse et la diversité des espèces et engendré une perte des AG liés au succès de reproduction et fécondité. La perte des AG essentiels associés à 1' augmentation de carbone dans les lacs peuvent expliquer les changements écologiques dans les communautés de zooplancton crustacé, et peuvent avoir des conséquences nutritionnelles négatives pour les consommateurs d'ordre supérieur dans la chaîne alimentaire aquatique. Mots Clés: acides gras, changements climatique, écosystèmes d'eau douce, limnologie, zooplancton vii ABSTRACT Freshwater lakes may suffer an increase in terrestrial organic matter associated with climate change, of which the effects on the aquatic food web are unknown. Fatty acid (FA) profiles can provide a mechanistic approach to understanding the responses of the zooplankton community in response to environmental changes such as an increase in dissolved organic carbon (humic) and an increase of nutrients. With the use of in-lake mesocosms in the Laurentians (QC), different resource acquisition pathways for zooplankton were created by encouraging or discouraging the consumption of algae. A single zooplankton community was exposed to treatments: control, nutrients (nitrogen + phosphorus), humic and humic + nutrients. The duration of the experiment was 6 weeks and the response variables were abundance, biomass, diversity and species composition, and FA profiles of major zooplankton taxa. Compared to the ambient treatment, environments favoring phytoplankton (nutrient treatment) induced an increase in the relative abundance ofzooplankton, species diversity, and FA linked to fertility. Humic and humic + nutrients treatments decreased abundance, biomass and species diversity and resulted in a loss of FA related to reproductive success and fertility. The loss of essential FA associated with the increase of carbon in lakes may exp lain the ecological changes in the crustacean zooplankton communities, and may have negative nutritional consequences for higher arder consumers in the aquatic food chain. Key Words: Fatty acids, climate change, freshwater ecosystems, limnology, zooplankton 8 CHAPITRE! 1.1 Introduction to research Freshwater ecosystems in northern reg10ns may expenence increases m tenestrial-somce nutrients and dissolved organic carbon (DOC) that could be augmented by both land use change and increased precipitation associated with climate change (Jeppesen et al. 2009). Dissolved organic carbon can be produced naturally within a freshwater lake (autochthonous) or can be loaded into lakes via terrestrial input (allochthonous) (Larsen et al., 2009). These effects are anticipated to have cascading effects on the quality of basal resources for primary consumers, with potential consequences for the abundance and nutritional state of crustacean zooplank:ton. Crustacean zooplankton are a key energy link in aquatic food webs as they occupy an intermediate trophic position between basal resources (phytoplankton and heterotroplucally-upgraded bacterial resources) and vertebrate consumers (Thorp and Covich 201 0). My thesis tested how enriched and suppressed basal resource pathways resulting from altered nutrient and allochthonous DOC inputs can change crustacean zooplank:ton commtmities, both from an ecological and biochen'llcal perspective. Anthropogeruc-somce tetTestrial runoff has been the subject of interest of many limnological studies, as they can have profound effects on food webs m freshwater aquatic systems (Edmonson & Lehrunan, 1979; Schjndler et al., 1977;