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Evidence for negative effects of drought on Baetis sp. (small minnow mayfly) abundance in a southern California stream
Full text linkBenthic macroinvertebrate (BMI) sampling was conducted at two sites in Topanga Creek from 2003-2014. During this period, Southern California experienced extreme drought conditions (US Drought Monitor 2014). Examining trends in species composition over this period allows for a relatively long-term analysis of potential effects of drought on BMI communities. The Southern California Coastal Index of Biotic Integrity (SCC-IBI; Ode 2007) was applied to BMI samples from Topanga Creek to measure the effects of drought on quantitative biotic integrity. The following trends regarding the BMI community of Topanga Creek emerged during the course of this study: 1) Wet year rainfall in Topanga Creek Watershed positively correlated to relative and per sq. ft. springtime abundance of Baetis sp., relative abundance of Simulium sp. up to 31” rain, and negatively correlated to relative abundnace of Chironomidae n.d., 2) percent algae cover in April and May positvely correlated to abundance per sq. ft. Baetis sp. and Simulium sp., and 3) multiple regression analysis revealed a negative relationship between Chironomid n.d. and Baetis sp. abundance. BMI are an important food source for endangered steelhead trout and other native aquatic and terrestrial insectivorous species of special concern; significant changes to the BMI community could have trophic reprecussions for these and other wildlife. Long-term monitoring is important for tracking the influence of changes in climatic conditions on BMI community
The Bigeye Scad, Selar crumenophthalmus (Bloch, 1793) (Family Carangidae), New to the California Marine Fauna, with a List to and Keys for All California Carangids
Full text linkWe report on the collection of a Selar crumenophthalmus (Bloch, 1793), the bigeye scad. The fish was captured in the midwaters of a kelp bed (bottom depth 8 m) off northern Rancho Palos Verdes (33°48\u27N, 118°24\u27W), southern California. This is the first time this species has been reported from off California. The fish was one of approximately 10 conspecifics that were swimming with a school of juvenile jack mackerel, Trachurus symmetricus (Ayres, 1855). In addition to the report of this capture, we provide a list to and keys for all California carangids
The Return of the King of the Kelp Forest: Distribution, Abundance, and Biomass of Giant Sea Bass (Stereolepis gigas) off Santa Catalina Island, California, 2014-2015.
Full text linkIt is rare to find evidence of top predators recovering after being negatively affected by overfishing. However, recent findings suggest a nascent return of the critically endangered giant sea bass (Stereolepis gigas) to southern California. To provide the first population assessment of giant sea bass, surveys were conducted during the 2014/2015 summers off Santa Catalina Island, CA. Eight sites were surveyed on both the windward and leeward side of Santa Catalina Island every two weeks from June through August. Of the eight sites, three aggregations were identified at Goat Harbor, The V’s, and Little Harbor, CA. These three aggregation sites, the largest containing 24 individuals, contained a mean stock biomass of 19.6 kg/1000 m2 over both summers. Over the course of the both summers the giant sea bass population was primarily made up of 1.2 - 1.3 m TL individuals with several small and newly mature fish observed in aggregations. Comparison to historical data for the island suggests giant sea bass are recovering, but have not reached pre-exploitation levels
