Community–habitat relationships in coastal streams in Big Sur, California, USA: travertine influences macroinvertebrate abundance and community structure

Abstract

Travertine deposition occurs in streams worldwide but its effects on stream communities are poorly understood. I sampled benthic macroinvertebrates, periphyton, and reach-scale environmental variables in coastal streams in Big Sur, central California, USA, to determine the specific effects of travertine that occurred at some sites as well as to provide a broader assessment of community-habitat relationships. Total density and biomass of macroinvertebrates varied 6-and 9-fold across sites, respectively, and chlorophyll a concentrations varied 10-fold, but invertebrate and periphyton abundances were not correlated. Baetis tricaudatus (Ephemeroptera), Simuliidae (Diptera), and Chironomidae (Diptera) dominated macroinvertebrate communities across all sites, although differences in the relative abundances of these and other taxa produced moderate variation in community structure among sites (Bray-Curtis similarity coefficients of 47-84). Variation in community structure was related to a number of habitat features, notably travertine but also including variables reflecting channel morphology, flow, substrate size, and riparian tree type. Median density and biomass of macroinvertebrates were more than twice as high at sites without travertine than sites with travertine. Taxa richness also was higher at sites without travertine, and community structure differed moderately between sites with and without travertine, although there were no particular assemblages associated with either group. Non-metric multidimensional scaling (MDS) and cluster analysis of similarities in community structure appeared to separate sites with either travertine or high fines from sites without those conditions. These results demonstrate that travertine can have strong effects on stream communities, and additional studies are needed to identify the full range of effects on ecosystems and to evaluate the potential consequences of travertine for conservation efforts such as biomonitoring programs and threatened species management.

Diet Variability of Steelhead/Rainbow Trout in a Coastal Basin in Central California: Relative Importance of Seasonal, Spatial, and Ontogenetic Variation

“…The extent of travertine in Devils Creek varied, but in most places (except for deep pools) it was sufficient to cement substrate particles to one another and in some patches was thick enough to form a thin film or crust over the streambed. Travertine was absent during winter—presumably removed by scour during high flows—and this appears to be an annual phenomenon in Devils Creek and several other streams along the Big Sur coast that affects the abundance and community structure of benthic macroinvertebrates (Rundio ). The most abundant riparian trees in both reaches were coast redwood Sequoia sempervirens , white alder Alnus rhombifolia , and bigleaf maple Acer macrophyllum .…”

Importance of non‐native isopods and other terrestrial prey resources to steelhead/rainbow trout Oncorhynchus mykiss in coastal streams in Big Sur, California

“…energy content of all prey in the stomach contents and drainage area, and frequency and proportion of isopods and channel gradient) suggest that there may be some finer scale diet–environment relationships within the region that were beyond the scope of our study. For instance, in previous studies in many of these same streams, we found that the abundance and taxonomic richness of benthic macroinvertebrates was lower in sites with travertine (calcium carbonate) deposition than in sites without (Rundio, 2009; Rundio & Lindley, 2008), but in this study there was no indication of differences in diet between sites with travertine (Partington, Devils, Limekiln, and Mill creeks) and those without based on general inspection of the results (we did not conduct formal tests for differences due to small and unbalanced number of sites with and without travertine). Our ability to detect differences may have been limited by the high variability in diet among individual fish, by our samples being limited to a single date per site, and by our sample comprising all size and age classes, whereas differences corresponding to benthic invertebrates are most likely to occur among smaller size classes that feed predominantly on aquatic prey.…”

“…This included differences related to fish size, which is often a large source of diet variation in stream salmonids and in particular may influence the use of terrestrial prey (Dineen et al, 2007; Gustafsson et al, 2010; Syrjänen et al, 2011) including non‐native isopods (Rundio & Lindley, 2019). Finally, although landscape conditions across the Big Sur coast are relatively similar in terms of major features such as landform, forest type, low level of development, and climate, the region is large (>100 km from north to south) and there is some local variation in geology and other environmental conditions (Rundio, 2009), so we also sought to determine whether there were large‐scale geographic patterns or trends in diet or riparian isopod abundance. Specifically, we sampled O. mykiss diets and riparian isopods in 11 basins on the Big Sur coast (including Big Creek) during summer to evaluate (a) variation in the energetic value, taxonomic composition, and proportions of terrestrial prey and non‐native isopods in the diet among sites and with respect to fish size; (b) the occurrence and density of non‐native isopods on streambanks and correlations with occurrence in the diet; and (c) relationships between diet and isopod density and geographic/landscape variables.…”

Response of periphyton to nutrient addition in a tufa-depositing environment

“…Reduction in the diversity of fauna and flora as a result of calcareous deposition was suggested by Pitois et al (2001). Also, Rundio (2009) found a lower biomass and diversity of freshwater macroinvertebrates in streams with tufa deposition compared to streams without tufa. Opposing results have also been documented, i.e.…”