Timeline of Sargassum horneri invasion in Southern California - PowerPoint PPT Presentation

T HE F AUNAL C OMMUNITIES A SSOCIATED WITH S ARGASSUM HORNERI Stephanie Saccardi Santa Barbara City College Biological Sciences M ENTOR : Lindsay Marks F ACULTY A DVISOR : Dan Reed Marine Science Institute Credit: Jack Engle F UNDED B Y : Santa Barbara Coastal Long Term Ecological Research Network

Timeline of Sargassum horneri invasion in Southern California Credit: David J. Kushner

Why care about invasive species? Invasive species may cause harm to the environments they populate . Credit: Jack Engle Credit: Jessie Alstatt …and change the structure of food webs They can outcompete native species for food or resources… Threatened biodiversity?

Objectives: 1. Determine abundance and variety of organisms colonizing on Sargassum horneri Senorita fish grazing S. horneri Credit: Jack Engle 2. Compare the communities found on Sargassum horneri to those on native kelps Lindsay collecting alga samples

Observing the microfauna on Sargassum horneri Lindsay collects Samples are sieved and Invertebrates are sorted, samples of Sargassum placed in a sorting dish counted, and measured

50X 50X 25X 25X Class Ophiuroidea Class Polychaeta Suborder Gammaridea Family Brittle star Worm Gammarid Sphaeromatidae Isopod Suborder Caprellidea Order Decapoda Family Idoteidae Class Gastropoda Caprellid Shrimp Isopod Snails 3.125 mm 6.25 mm 25X 25X 25X 50X

Assemblage of invertebrates differs among Macrocystis pyrifera and Sargassum horneri 8000 10000 7000 7000 6000 8000 6000 5000 5000 6000 4000 4000 3000 4000 # of individuals/kg wet algae 3000 2000 2000 2000 1000 3.2 1000 8.6 0 0 0 Gammarid amphipods Copepods Caprellid amphipods 450 600 4000 400 3500 500 350 3000 300 400 2500 250 300 2000 200 150 1500 200 100 1000 25.0 100 50 500 0 0 0 Mysids Shrimps Isopods

Two different habitats to choose from: Credit: bio.classes.ucsc.edu Credit: Jack Engle Macrocystis pyrifera : morphologically Sargassum horneri : a more complexly simple structured habitat for invertebrates

Invertebrate biomass is comparable between Macrocystis pyrifera and Sargassum horneri 4500 1200 mg invertebrate/kg wet algae 4000 1000 3500 3000 800 2500 600 2000 1500 400 1000 200 500 0 0 Gammarid amphipods Shrimps

Challenge: Redefining a new length-weight relationship 10 Dry Weight of Shrimp (mg) New Equation for Coyer’s Equation Shrimp 5 0 1.0 1.5 2.0 Length (mm)

Future Directions Sample all locations where Sargassum horneri has spread Temperature (°C) Credit: www.noaa.gov

Acknowledgements • SBC LTER • MCR LTER • INSET • NSF