Land use, watershed processes, and coastal biodiversity are often intricately linked, yet land-sea interactions are usually ignored when selecting terrestrial and marine reserves with existing models. Such oversight increases the risk that reserves will fail to achieve their conservation objectives. The conceptual model underlying existing reserve selection models presumes each site is a closed ecological system, unaffected by inputs from elsewhere. As a short-term objective, we recommend extending land-conservation analyses to account for effects on marine biodiversity by considering linkages between ecosystems. This level of integration seems feasible and directly relevant to agencies and conservancies engaged in protecting coastal lands. We propose an approach that evaluates terrestrial sites based on whether they benefit or harm marine species or habitats. We then consider a hypothetical example involving estuarine nurseries. Whether this approach will produce more effective terrestrial reserves remains to be seen.

Oceanic sources of nutrients to the kelp forests of the Santa Barbara Channel were diagnosed using time series from three moorings in 12‐ to 17‐m water depth. An in situ nitrate autoanalyzer on the moorings provided the first high‐resolution time series of nitrate + nitrite (dissolved inorganic nitrogen, DIN) concentrations for this environment. Measurements between February 2001 and May 2003 show that the major mechanisms that supply DIN to the inner shelf of the Santa Barbara Channel are upwelling, diurnal internal motions, and storm runoff. These supply mechanisms vary in importance seasonally. Upwelling dominates increases of inner‐shelf DIN concentration between March and May and accounts for more than half of the annual advective DIN transport to shelf reefs. In summer, baroclinic motions akin to internal waves are an important source of DIN because they occur when surface nutrient concentrations are depleted and other supply mechanisms are inactive. Brief episodes of upwelling become important in late autumn and early winter. DIN inputs from storm runoff, detected as salinity dilution at the moorings and estimated from measurements of stream discharge and nutrient concentration, are significant during winter runoff events.

Oceanic sources of nutrients to the kelp forests of the Santa Barbara Channel were diagnosed using time series from three moorings in 12- to 17-m water depth. An in situ nitrate autoanalyzer on the moorings provided the first high-resolution time series of nitrate + nitrite (dissolved inorganic nitrogen, DIN) concentrations for this environment. Measurements between February 2001 and May 2003 show that the major mechanisms that supply DIN to the inner shelf of the Santa Barbara Channel are upwelling, diurnal internal motions, and storm runoff. These supply mechanisms vary in importance seasonally. Upwelling dominates increases of inner-shelf DIN concentration between March and May and accounts for more than half of the annual advective DIN transport to shelf reefs. In summer, baroclinic motions akin to internal waves are an important source of DIN because they occur when surface nutrient concentrations are depleted and other supply mechanisms are inactive. Brief episodes of upwelling become important in late autumn and early winter. DIN inputs from storm runoff, detected as salinity dilution at the moorings and estimated from measurements of stream discharge and nutrient concentration, are significant during winter runoff events. Quantification of variability in nutrient transport is important for understanding the maintenance of shallow- water coastal ecosystems. The transport of nutrients to shallow (,20 m) reefs is critical for the persistence and health of the giant kelp, Macrocystis pyrifera (Jackson 1977; Wheeler and North 1980), the dense stands of which provide habitat for numerous other species (Dayton 1985). The delivery of nitrate is of particular concern because nitrogen is thought to be the nutrient element that most often limits kelp growth (Jackson 1977; Zimmerman and Kremer 1984). Describing nutrient-exchange across the inner shelf is complicated since continental-shelf dynamics (along-shelf currents and associated Ekman transport, fronts, internal waves), nearshore dynamics (e.g., breaking surface waves and alongshore drift), and runoff from terrestrial watersheds are all potentially important pro- cesses. The interactions among these processes off Southern

(2005). Episodic variations in nutrient concentrations in coastal Californian streams. SIL Proceedings, 1922-2010: Vol. 29, No. 2, pp. 1049-1053.

Along the southern California coast, near Santa Barbara, California, we are measuring nutrient export from specific land uses and developing relationships to predict nutrient export at a watershed scale. The area is characterized by a Mediterranean-like climate and short steep catchments producing flashy runoff. Land uses include chaparral, avocado orchards, greenhouse agriculture, open-field nurseries, and residential and commercial development. Sampling sites are located on defined drainages or storm drains that collect runoff from relatively homogeneous areas representing each land use. Stream water samples are taken once a week during the rainy season, every two weeks during the dry season and every 1-4 h during storms; samples are analyzed for nitrate, ammonium, and phosphate. We determine discharge from measurements of stage derived from pressure transducers at all sampling sites. This information is then converted to flux at a high temporal resolution.Several parameters are presented in an initial effort to build relationships for simulating nutrient export based on land use, precipitation and antecedent soil moisture conditions. The objective is to create robust relationships, using parameters in a simple and cost efficient manner, which can be extended to other coastal watersheds with similar land uses and climate. The effort focuses on nitrate and soluble reactive phosphorus (SRP). The relationship of volume-weighted mean nutrient concentration and runoff/rainfall ratios shows promise as a means of predicting nutrient export in flashy streams experiencing a Mediterranean climate. (c) 2005 Elsevier B.V. All rights reserved.

Along the southern California coast, near Santa Barbara, we are (1) measuring nutrient loading to the nearshore environment from representative watersheds, and (2) developing a model to predict export from changes in land use. The area is characterized by a Mediterranean climate and short steep catchments producing flashy runoff; a majority of the annual nutrient export occurs within a few days each year. Six land use classes within the drainages of the Carpinteria Valley are being sampled to develop a nutrient export coefficient model within the context of a geographic information system (natural/undisturbed chaparral vegetation, avocado orchards, greenhouse agriculture, open-field nursery agriculture, residential development, and commercial and light industrial development). The sites chosen represent relatively homogeneous areas for each of the land use classes and are large enough to have defined drainages. Stream water samples were collected either manually, just below the water surface in the thalweg, or by auto-samplers. Water samples were taken every two weeks during the dry season, approximately May through October, once a week during the rainy season, and every one to four hours during storms. At most sites, stage was measured with pressure transducers at 5-minute intervals, and staff gauges have been installed to visually observe stage during sampling. Nitrate concentrations during baseflow varied over three orders of magnitude, from a few micromoles per liter (μmol/L) in undeveloped catchments, to hundreds of μmol/L in agricultural and urban watersheds, to thousands of μmol/L where intensive greenhouse agriculture dominates. Nitrate loading ranged from a few moles per hectare per storm at undeveloped and residential sites to hundreds of moles per hectare per storm at the greenhouse site. Phosphate concentrations had a similar, but smaller, variation from 1 to 100 μmol/L. Stormflow concentrations fluctuated with the storm hydrograph: phosphate increased with flow, while nitrate typically decreased due to dilution from impervious surface runoff. Future research will entail implementing nutrient export coefficient modeling techniques to enable a regional analysis of nutrient loading to the ocean.

To address the responses of the very dilute waters in the Sierra Nevada, California, to acidic atmospheric deposition, the Alpine hydrochemical model (AHM) was used to simulate 47 years of runoff and solute concentrations in the Emerald Lake catchment. The AHM is a semi-distributed model of alpine watersheds that incorporates representations of the major hydrologic and biogeochemical processes that control stream chemical composition. Proxy data of discharge and snowfall were used to develop the necessary inputs for the 47-year runs. The long-term simulations were stable, but conflicts in the simulation of base cation and silica concentrations indicate that the model has a missing process or misrepresents mineral weathering. Sensitivity analysis of the weathering parameters indicates that a weathering rate of approximately 80% of the value fitted based on a one-year calibration would match the observed base saturation and the initial one year estimate had incorrect stoichiometry. Additionally, comparison of annual modeled mass flux to observed mass flux indicates that the model overestimates cation and silica export in dry years and underestimates export in wet years. Our results indicate that the Emerald Lake watershed, as represented by AHM, is not sensitive to chronic acidification with atmospheric deposition at current levels and that there would be little episodic acidification with a doubling in atmospheric deposition. However, in the simulations climate variability had an impact on stream water pH and this sensitivity should be taken into account in assessing alpine catchment sensitivity to changes in atmospheric deposition.

This study, presented at the 2003 AGU winter session in San Francisco, and at the ACS summer meeting in Philadelphia, concerns inter-annual variations in river channel functioning and their effect on nutrient uptake at the lower 4 river locations shown on the map. The Ventura , like most southern California coastal streams, ends in a tidal estuary. The EPA has proposed N and P limits for the prevention of eutrophication in this area: they are 0.38 mg/L for nitrogen and 0.03 mg/L for phosphorus. The graph shows nitrate and phosphate concentrations at the tidal limit (VR01). Nitrate is sometimes above this limit; phosphate is always above. The limits are for nitrogen and phosphorus and the graph shows nitrate and phosphate, so the actual situation is a slightly worse than portrayed; nitrate and phosphate make up most of the nitrogen and phosphorus in the river (especially during the dry season), but not all. “Bluish” areas mark the typical rainy season (mid-November to mid-March) and we have chosen to show the respective nitrate and phosphate axes in a proportion of 12:1 (in mg/L); this represents a molar ratio of approximately 30:1, i.e., the general ratio of molecular N and P uptake by freshwater aquatic primary producers. When phosphate appears above nitrate in the graph, nitrogen becomes the limiting nutrient; when nitrate appears above phosphate, phosphorus is limiting; when roughly equal, they are in balance and neither is limiting growth. Notice that the river at this location, while sometimes P-limited, is mostly N-limited, especially during the dry season. The graph shows the nitrate concentration divided by the phosphate concentration for each month’s sampling data at the river mouth (VR01) and illustrates the nutrient status of river water going into the Ventura estuary. Bluish vertical bars show rainy seasons and the thick horizontal green bar represents a molecular ratio of 20 to 30:1; the zone where both nutrients are in balance. If the ratio is above the line, water going into the lagoon is phosphorus limited, if below the line, nitrogen limited. Winters and early spring are mostly in-balance or phosphorus limited, while the remainder of the dry-season is nitrate limited. And in some years, drier, low-rainfall years, freshwater supplying the lagoon becomes severely nitrogen deficient. suspect Low stream and drifting sand along the coast often close these small estuaries time half a

Two-component hydrograph separations were performed for three, nested, snowmelt-dominated catchments in Sequoia National Park. The purpose of the hydrograph separations was to: (i) differentiate between the old and new water contributions to discharge during snowmelt using delta(18)O signatures; (ii) identify the fraction of snowmelt that travelled through the subsurface (reactive) compartment during the snowmelt period using silica or sodium; and (iii) investigate the impact of changing end-member signatures on the separations. 'Old' water refers to water that was stored in the watershed during the previous year, whereas 'new' water is current snowmelt. Hydrograph separations were performed for both a high-accumulation (1998, annual precipitation 2(.)4 m) and an average year (1999, 1(.)3 m). The proportion of old water contribution to discharge during the rising limb of the hydrograph was 10-20%, with 80-100% of snowmelt being reactive, i.e. passing through soil and talus. Estimates of old and new soil water and direct snowmelt entering the stream varied among the catchments in 1999. Differences between these components were minimal in 1998, regardless of varying topography and differing proportions of soil, rock and talus. Using time-dependent rather than constant delta(18)O meltwater and silica soil-water signatures made a meaningful impact on both new and old water, and reactive and unreactive, estimates. Copyright (C) 2004 John Wiley Sons, Ltd.

Mechanisms underlying catchment export of nitrogen (N) during seasonal transitions (i.e., winter to spring and summer to autumn) were investigated in high-elevation catchments of the Sierra Nevada using stable isotopes of nitrate and water, intensive monitoring of stream chemistry and detailed catchment N-budgets. We had four objectives: (1) determine the relative contribution of snowpack and soil nitrate to the spring nitrate pulse, (2) look for evidence of biotic control of N losses at the catchment scale, (3) examine dissolved organic nitrogen ( DON) export patterns to gain a better understanding of the biological and hydrological controls on DON loss, and (4) examine the relationship between soil physico-chemical conditions and N export. At the Emerald Lake watershed, nitrogen budgets and isotopic analyses of the spring nitrate pulse indicate that 50 to 70% of the total nitrate exported during snowmelt (ca. April to July) is derived from catchment soils and talus; the remainder is snowpack nitrate. The spring nitrate pulse occurred several weeks after the start of snowmelt and was different from export patterns of less biologically labile compounds such as silica and DON suggesting that: (1) nitrate is produced and released from soils only after intense flushing has occurred and (2) a microbial N-sink is operating in catchment soils during the early stages of snowmelt. DON concentrations varied less than 20–30% during snowmelt, indicating that soil processes tightly controlled DON losses.

Interannual variations in nitrogen mass balances for the Emerald Lake watershed (ELW) and six additional headwater basins of the Sierra Nevada of California are described and used to investigate the influence of physical (snow regime, runoff, and precipitation) and chemical (N loading) forcings on the observed variability in annual catchment yield and retention of N. At ELW, annual yield of N varied by a factor of 8 (0.4–3.2 kg ha−1 yr−1) and was a linear function of runoff (R2 = 0.89 and 0.74 for dissolved inorganic nitrogen and dissolved organic nitrogen, respectively). Nitrogen yield increased faster than increases in runoff; that is, ecosystem processes enhanced N losses during years with high runoff and retarded losses during dry years. The timing of snowmelt runoff had a large effect on catchment inorganic N dynamics: nitrate pulses were greater and DIN retention was lower in years with deep, late melting snowpacks. We hypothesize that in the Sierra Nevada, labile N pools in soils are increasingly stocked during years with high snowfall amounts. These findings and modeling studies in high‐elevation watersheds suggest that if current trends toward warmer air temperatures and earlier snowmelt continue, N retention will increase in the Sierra Nevada.