Slide 1

Academic Year 2000-2001 By ALBA KATHERINE CALLES PROCEL Promotor Prof. Dr. MAGDA VINCX BIODIVERSITY OF THE MEIOBENTHOS OF SANDY BEACHES IN ECUADOR WITH EMPHASIS ON FREE-LIVING MARINE NEMATODES Slide 2 AIM To inventory the meiobenthos to higher taxa (Guayas province in Ecuador). To identify the nematode communities to genus level. To establish a relationship between the nematode and the environmental factors. To establish the value of meiofauna (nematodes) as bio-indicator of anthropogenic impact. Slide 3 San Pablo Salinas Playas N Biodiversity of Meiobenthos with emphasis on Free-Living Marine Nematodes/Ecuador Position of Ecuador in South America Pacific Ocean Olon Cenaim Guayas Province San Pablo Salinas Playas N AREA OF STUDY Artesanal beach Tourist beach Tourist/Artesanal beach Slide 4 Biodiversity of Meiobenthos with emphasis on Free-Living Marine Nematodes/Ecuador SALINAS SAN PABLO SANDY BEACHESSANDY BEACHES Salinas and Playas are recreational beaches, during weekends and holidays. San Pablo and Cenaim are lesser disturbed, except for the ongoing local artisanal fishery activities Slide 5 Biodiversity of Meiobenthos with emphasis on Free-Living Marine Nematodes/Ecuador METHODOLOGY Sampling: Four replicates; during low tide level; cores of 3.2 diameter. Fixation: 4% formalin. Extraction: Decantation (ten times) and centrifugation (three times) with LUDOX (1.18 density). Slide 6 Biodiversity of Meiobenthos with emphasis on Free-Living Marine Nematodes/Ecuador METHODOLOGY (Laboratory) Glycerol-ethanol (DE GRISSE, 1969b) Paraffin is melted and the slide is sealed (COBB SLIDE, 1917) Counting meiofauna and pick up nematodes MOUNTINGCOUNTING Slide 7 Biodiversity of Meiobenthos with emphasis on Free-Living Marine Nematodes/Ecuador RESULTS Slide 8 Biodiversity of Meiobenthos with emphasis on Free-Living Marine Nematodes/Ecuador RESULTS Slide 9 Biodiversity of Meiobenthos with emphasis on Free-Living Marine Nematodes/Ecuador Sediment analysis RESULTS Slide 10 Biodiversity of Meiobenthos with emphasis on Free-Living Marine Nematodes/Ecuador RESULTS Densities of meiofauna (ind./10 cm 2 ) Slide 11 RESULTS Biodiversity of Meiobenthos with emphasis on Free-Living Marine Nematodes/Ecuador Composition of meiofauna taxa Slide 12 RESULTS Biodiversity of Meiobenthos with emphasis on Free-Living Marine Nematodes/Ecuador Nematoda Genus diversity-indices (Hills numbers) A total of 19 genera belonging to 14 families identified Slide 13 RESULTS k-dominance curve for the nematode genera Biodiversity of Meiobenthos with emphasis on Free-Living Marine Nematodes/Ecuador Slide 14 RESULTS Relative abundance of nematode feeding type (according to Wieser) per station % Biodiversity of Meiobenthos with emphasis on Free-Living Marine Nematodes/Ecuador Slide 15 RESULTS Relative abundance of nematode structure per station Biodiversity of Meiobenthos with emphasis on Free-Living Marine Nematodes/Ecuador Slide 16 RESULTS TWINSPAN dendrogram based on the abundance (%) of nematode genera (Cut level: 0, 2, 5, 10 and 20) Cenaim (A) Cenaim (B) San Pablo (A) San Pablo (B) Playas (A) Playas (B) Salinas (A) Salinas (B) Olon I (A) Olon I (B) Sabatiera Halalaimus Gonionchus Odontanticoma GENERA Biodiversity of Meiobenthos with emphasis on Free-Living Marine Nematodes/Ecuador Slide 17 RESULTS Biodiversity of Meiobenthos with emphasis on Free-Living Marine Nematodes/Ecuador Slide 18 RESULTS Metadesmolaimus plot per stationParacyatholaimus plot per station Slide 19 Biodiversity of Meiobenthos with emphasis on Free-Living Marine Nematodes/Ecuador Longitudinal ornamentation (as rod-like structures) Six lips very high and weakly cuticularized Amphid circular Gonionchus sp. n. Slide 20 Biodiversity of Meiobenthos with emphasis on Free-Living Marine Nematodes/Ecuador Longitudinal ornamentation starts at irregular levels in the cervical region and go throughout the whole body length. Protrusion of the spicules Gonionchus sp. n. Slide 21 CONCLUSION Meiofauna: highest density Cenaim (2226-2544 ind./10 cm 2 ) lowest density Salinas (349-558 ind./10 cm 2 ) Chlorophyll a, SPM and POM (Salinas and Olon) meiofauna density NEMATODES: 312-2398 ind./10cm 2 87% of meiofauna Gastrotricha: second most dominant taxon of meiofauna; mainly in Playas (324-389 ind./10 cm 2 ) Diversity: higher in Playas B, (N 0 = 14); lowest in San Pablo, (N 0 =6) nematode density (Playas= 614, S. Pablo= 2190 ind./10cm 2 ). HIGHESTdiversity LOWEST density Description of one new species of Gonionchus Biodiversity of Meiobenthos with emphasis on Free-Living Marine Nematodes/Ecuador Slide 22 THE END