EnvORG Environmental Observations and Research Group

Trampling through streams and creeks may disrupt aquatic ecosystems by altering the landscape and displacing wildlife. Aquatic invertebrates are often used as indicators of water quality in stream ecosystems. We examined the effects of trampling on the aquatic invertebrate community and measured the absolute abundance, relative abundance, species richness, and species diversity at two (upper and lower) sites on Bell Creek in Orange County, CA. We used the California Streamside Biosurvey Protocol of aquatic invertebrates as guidelines for sampling and to determine creek health.

The California grunion, Leuresthes tenuis, spawns on shore during spring high tides and fertilized eggs incubate 9-14 days until wave action stimulates hatching during the next spring high tide series. Embryos that are not washed out can remain viable for at least 35 days and may hatch during subsequent spring high tides. We hypothesized that larvae fertilized at two different also monitored the environmental conditions that grunion embryos experience on three beaches in southern California.

Marine macroalgal consumers are known to preferentially feed on certain seaweeds. Several factors, including consumers’ ability to effectively handle, eat, assimilate, and allocate consumed energy, may drive food choices. Previous research revealed that two southern California consumers, crabs (Pachygrapsus crassipes) and urchins (Strongylocentrotus purpuratus), fed upon both native (Macrocystis pyrifera) and non-native (Undaria pinnatifida) kelps; however, when given a choice, crabs chose to feed on Undaria while urchins chose Macrocystis.

Natural habitats in the valley and foothill areas of coastal southern California have been diminished over the past century as a result of intensive human development and sprawl. The loss, conversion and fragmentation of native vegetation have altered animal communities throughout the region as well, leaving populations isolated from one another and the remaining open space in the surrounding mountains and parks.