Seasonal Ponds Research Articles

Breeding in the stable boreal landscape: lake habitat variability drives brood production in the teal (Anas crecca)

Summary Boreal forest lakes are normally considered stable environments, but from a duck's point of view, both resource abundance and habitat quality in the lakes may differ from 1 year to another. Duck species differ in their flexibility to respond to variation in environmental factors, such as habitat quality, habitat variability and weather. Anas crecca, the common teal, has been suggested to be a species that can readily colonise newly formed habitat. We studied the effect of habitat quality (invertebrate food resources, amount of spring flood, beaver flood abundance, predation pressure), weather (temperature, precipitation, timing of ice break‐up) and pair abundance on breeding success of teal at the landscape scale in Southern Finland. We used 20 years of data (1989–2008) from a study area consisting of 50 lakes. This is typical boreal breeding area for the teal, whose population size is markedly variable. We express breeding success as number of broods in two different age classes. The number of broods in both age classes was explained well by habitat quality, but different variables seem to operate during different phases of the breeding season. Increases in abundance of breeding pairs and of food led to increased production of younger broods. Habitat factors including food and flood abundance were the most important predictors for older broods, which are the more influential in terms of recruitment. These factors manifested in an age‐specific manner, highlighting the importance of comprehensive breeding time surveys of boreal breeding ducks to understand variation in their recruitment. Our research underlines the importance of high‐quality habitats for breeding teal populations in the boreal forest landscape. The existence of these habitats depends substantially on human actions, such as managing beaver populations and preserving seasonal pond habitats.

Groundwater fluxes in a shallow seasonal wetland pond: The effect of bathymetric uncertainty on predicted water and solute balances

The successful management of groundwater dependent shallow seasonal wetlands requires a sound understanding of groundwater fluxes. However, such fluxes are hard to quantify. Water volume and solute mass balance models can be used in order to derive an estimate of groundwater fluxes within such systems. This approach is particularly attractive, as it can be undertaken using measurable environmental variables, such as; rainfall, evaporation, pond level and salinity. Groundwater fluxes estimated from such an approach are subject to uncertainty in the measured variables as well as in the process representation and in parameters within the model. However, the shallow nature of seasonal wetland ponds means water volume and surface area can change rapidly and non-linearly with depth, requiring an accurate representation of the wetland pond bathymetry. Unfortunately, detailed bathymetry is rarely available and simplifying assumptions regarding the bathymetry have to be made. However, the implications of these assumptions are typically not quantified. We systematically quantify the uncertainty implications for eight different representations of wetland bathymetry for a shallow seasonal wetland pond in South Australia. The predictive uncertainty estimation methods provided in the Model-Independent Parameter Estimation and Uncertainty Analysis software (PEST) are used to quantify the effect of bathymetric uncertainty on the modelled fluxes. We demonstrate that bathymetry can be successfully represented within the model in a simple parametric form using a cubic Bezier curve, allowing an assessment of bathymetric uncertainty due to measurement error and survey detail on the derived groundwater fluxes compared with the fixed bathymetry models. Findings show that different bathymetry conceptualisations can result in very different mass balance components and hence process conceptualisations, despite equally good fits to observed data, potentially leading to poor management decisions for the wetlands. Model predictive uncertainty increases with the crudity of the bathymetry representation, however, approximations that capture the general shape of the wetland pond such as a power law or Bezier curve show only a small increase in prediction uncertainty compared to the full dGPS surveyed bathymetry, implying these may be sufficient for most modelling purposes.

Surface and melt pond evolution on landfast first-year sea ice in the Canadian Arctic Archipelago

The evolution of landfast sea ice melt pond coverage, surface topography, and mass balance was studied in the Canadian Arctic during May–June 2011 and 2012, using a terrestrial laser scanner, snow and sea ice sampling, and surface meteorological characterization. Initial melt pond formation was not limited to low-lying areas, rather ponds formed at almost all premelt elevations. The subsequent evolution of melt pond coverage varied considerably between the 2 years owing to four principle, temporally variable factors. First, the range in premelt topographic relief was 0.5 m greater in 2011 (rougher surface) than in 2012 (smoother surface), such that a seasonal maximum pond coverage of 60% and maximum hydraulic head of 204 mm were reached in 2011, versus 78% and 138 mm in 2012. A change in the meltwater balance (production minus drainage) caused the ponds to spread or recede over an area that was almost 90% larger in 2012 than in 2011. Second, modification of the premelt topography was observed during mid-June, due to preferential melting under certain drainage channels. Some of the lowest-lying premelt areas were subsequently elevated above these deepening channels and unexpectedly became drained later in the season. Third, ice interior temperatures remained 1–2°C colder later into June in 2012 than in 2011, even though the ice was 0.35 m thinner at melt onset, thereby delaying permeability increases in the ice that would allow vertical meltwater drainage to the ocean. Finally, surface melt was estimated to account for approximately 62% of the net radiative flux to the sea ice cover during the melt season.

Impacts of climate variability on wetland salinization in the North American prairies

Abstract. The glaciated plains of the North American continent, also known as the "prairies", are a complex hydrological system characterized by hummocky terrain, where wetlands, containing seasonal or semi-permanent ponds, occupy the numerous topographic depressions. The prairie subsoil and many of its water bodies contain high salt concentrations, in particular sulfate salts, which are continuously cycled within the closed drainage basins. The period between 2000 and 2012 was characterized by an unusual degree of climatic variability, including severe floods and droughts, and this had a marked effect on the spatial distribution, water levels and chemical composition of wetland ponds. Understanding the geochemical and hydrological processes under changing environmental conditions is needed in order to better understand the risk and mitigate the impacts of future soil and water salinization. Here we explore salt dynamics in the prairies using field observations from St. Denis, Saskatchewan, taken mostly over the last 20 years. Measurements include meteorological data, soil moisture, soil salinity, groundwater levels and pond water volume, salinity, and chemical composition. The record includes periods of exceptional snow (1997, 2007) and periods of exception rainfall (2010, 2012), both of which resulted in unusually high pond water levels. Measurements indicated that severe pond salinization only occurred in response to extreme summer rainfall. It is hypothesized that since rainfall water infiltrates through the soil towards the depressions, while snowmelt water flows mainly as surface water over frozen soils, they have markedly different impacts on salt transport and pond salinization. Whilst this hypothesis is consistent with our conceptual understanding of the system, it needs to be tested further at a range of field sites in the prairies.

Hydrological Connectivity and Basin Morphometry Influence Seasonal Water-Chemistry Variations in Tundra Ponds of the Northwestern Hudson Bay Lowlands

Due to shallow depth and high surface area—to—volume ratio, ponds of the Hudson Bay Lowlands are vulnerable to climatic and hydrological changes, but relations between hydrological processes and limnological conditions remain unknown. Here, we measured water balance and limnological variables (water chemistry, suspended sediments, chlorophyll-a) at 20 ponds near Churchill (Manitoba) three times during the ice-free season of 2010 to explore relations among hydrological connectivity, basin morphometry, and waterchemistry variations. Using principal components analysis, we identified that the ponds followed one of four distinctive “seasonal water chemistry trajectories” (SWCT1–4). Most of the ponds that lacked apparent hydrologic connectivity displayed SWCT1, characterized by rising alkalinity and ionic content between early June and late July due to evaporative concentration. In contrast, most ponds with apparent hydrological connectivity displayed SWCT2 or SWCT3, characterized by marked changes in suspended sediment and total nitrogen concentrations due to inflow that transferred allochthonous materials from the catchment. Ponds in SWCT2 likely possessed temporary hydrological connections during periods of relatively high water supply and exhibited marked decline of suspended sediment and total nitrogen content when hydrological connection was lost. Most ponds in SWCT3 maintained active hydrological connections during all or most of the ice-free season and possessed relatively high suspended sediment and total nitrogen concentrations throughout the season. Ponds in SWCT4 possessed relatively stable water chemistry due to greater water depth and local features that reduced wind-induced sediment resuspension. We conclude that hydrological connectivity and basin morphometry exert important influence on seasonal pond water-chemistry dynamics.

Pronounced differences in genetic structure despite overall ecological similarity for two Ambystoma salamanders in the same landscape

Studies linking genetic structure in amphibian species with ecological characteristics have focused on large differences in dispersal capabilities. Here, we test whether two species with similar dispersal potential but subtle differences in other ecological characteristics also exhibit strong differences in genetic structure in the same landscape. We examined eight microsatellites in marbled salamanders (Ambystoma opacum) from 29 seasonal ponds and spotted salamanders (Ambystoma maculatum) from 19 seasonal ponds in a single geographic region in west-cen- tral Massachusetts. Despite overall similarity in ecological characteristics of spotted and marbled salamanders, we observed clear differences in the genetic structure of these two species. For marbled salamanders, we observed strong overall genetic differentiation (FST = 0.091, F 0 ST = 0.375), three population-level clusters of popula- tions (K = 3), a strong pattern of isolation by distance (r = 0.58), and marked variation in family-level structure (from 1 to 23 full-sibling families per site). For spotted salamanders, overall genetic differentiation was weaker (FST = 0.025, F 0 ST = 0.102), there was no evidence of population-level clustering (K = 1), the pattern of isolation by distance (r = 0.17) was much weaker compared to marbled salamanders, and there was less variation in family-level structure (from 10 to 36 full-sibling families per site). We suspect that a combination of breeding site fidelity, effective population size, and generation interval is responsible for these marked differences. Our results sug- gest that marbled salamanders, compared to spotted sala- manders, are more sensitive to fragmentation from various land-use activities and would be less likely to recolonize extirpated sites on an ecologically and conservation-rele- vant time frame.

Effects of feeding and fertilization on the growth and production of puntius sophore in seasonal ponds in Natore, Bangladesh

Context: Local farmers believe that the seasonal ponds and ditches which can retain water for 4 to 6 months in a year cannot be utilized for fish production but in fact such waters hold tremendous potential for culture of small indigenous fish species. Objectives: To evaluate the effects of fertilization and feeding in the growth and production of Puntius sophore culture in seasonal ponds. Materials and Methods: Six ponds were used during this study under two treatments. Two treatments such as T1 (only fertilizer) and T2 (fertilization and supplementary feeding) were run in triplicate. P. sophore was stocked in the two treatments at the rate of 15500 ha-1 after necessary pond preparation and fertilization. Results: Important physico-chemical factors viz., temperature, transparency, pH dissolved oxygen and total hardness of two treatments were found within the productive ranges. Four groups of phytoplankton were found in the ponds namely Bacillariophyceae, Chlorophyceae, Cyanophyceae and Euglenophyceae and two groups of zooplankton viz. Crustacea and Rotifera. P. sophore successfully breed in both treatments. However, the number of fish harvested was 122135 ha-1 in T1 and 113335 ha-1 in T2. Yet the total production was higher in T2 (1091.40 kg ha-1) than in T1 (842.72 kg ha-1) as the individuals found in T2 gained more weight than those in T1 reflecting the effects of regular feeding. Conclusion: The study indicated that both fertilizer and feed based treatment was to improve more production than only fertilizer based treatment under seasonal pond conditions. DOI: http://dx.doi.org/10.3329/jbs.v20i0.17735 J. bio-sci. 20: 135-142, 2012

Effects of Wetland Management on Carrying Capacity of Diving Ducks and Shorebirds in a Coastal Estuary

With global loss of natural wetlands, managed wetlands increasingly support energy requirements for wintering shorebirds and waterfowl. Despite numerous studies of avian bioenergetics in freshwater systems, less is known of the energetic capacity of estuarine systems. In San Francisco Bay, managed saline ponds converted from former commercial salt evaporation ponds form part of the largest wetland restoration project on the Pacific coast of North America. A daily-ration model was applied to assess carrying capacity for diving ducks and shorebirds during four winter seasons (2007–2010) in seasonal and circulation ponds, each in two salinity classes. Diving ducks comprised an estimated 35,450 ± 1,559 ( ± SE) in average years and 45,458 ± 1,653 in peak years with > 95% in circulation ponds. Shorebirds comprised 64,253 ± 14,838 ( ± SE) in average years and 108,171 ± 4,854 in peak years with > 64% in seasonal ponds. Macroinvertebrate energy density was highest in mesohaline (5–30 ppt) circulation ponds and lowest in seasonal ponds for both guilds. Energy requirements for diving ducks in mesohaline followed by low-hyperhaline (30–80 ppt) circulation ponds were mostly met by available prey energy. Available energy for shorebirds was substantially less than they required in seasonal ponds but exceeded their needs in mesohaline circulation ponds. Mesohaline circulation ponds supported 9,443 ± 1,649 ( ± SE) shorebird use-days·ha-1 of accessible habitat and 2,297 ± 402 diving duck use-days·ha-1 of accessible habitat, twice the capacity of low-hyperhaline circulation ponds and greater than five times that of seasonal ponds for both guilds. Our results indicated that reducing salinity to mesohaline levels and altering water depth to increase accessibility substantially increased energy available for these species in estuarine managed ponds.

Status of freshwater bodies from Ajara tahsil of Kolhapur district (MS), India with special reference to morphometric characteristics

The present attempt has been made to study the status of freshwater bodies from Ajara tahsil of Kolhapur District, Maharashtra, India by using Global Positioning System (GPS) with reference to survey and mapping. The investigation mainly focused on survey, location, mapping and submergence area of wetlands from this Tahsil. The results obtained from the study has compared with secondary data made available from Government authorities so as to reveal the percentage of change in the total submergence area of wetlands due to anthropogenic activities and other environmental factors. The study adds multi-temporal GPS information on the water bodies, which have prime importance to indicate environmental changes and anthropogenic activities. The present results indicate that 30 water bodies located in this tahsil, among which 5 are seasonal ponds while remaining are perennial water bodies. Total wetland area of tahsil is about 483.77 ha. The actual submergence area of Yarandol freshwater body was noted highest while lowest submergence was noted for Dabil pond. Since, emphasis is given on comparative morphometric features of6 minor irrigation tanks and 1 percolation water body. The comparative study revealed that the submergence area of all reservoirs got increased except

Production and Economics of Gift Strain of Tilapia (<i>Oreochromis niloticus</i>) in Small Seasonal Ponds

The production and economics of GIFT strain of tilapia (Oreochromis niloticus) reared in nine seasonal small ponds at Bangladesh Agricultural University campus for a period of three months during August to October were evaluated. The experiment was arranged in three treatments (T) each with three replications. The ponds were drained, limed and fertilized with organic and inorganic fertilizers during preparation. After stocking the fishes the ponds were fertilized weekly with cowdung, urea and TSP. Supplementary feed was not given in T1, but rice bran and mustard oilcake were given in T2 and commercial pellet feed in T3. Some water quality parameters were monitored at regular intervals and they were within acceptable range for aquaculture. The survival rates were high (>95%) in all treatments. Significantly highest production (3941.50 kg/ha in three months) was found in T3 followed by T2 (1845.5 kg/ha) and T1 (972.50 kg/ha). Similarly, significantly highest net return (Tk. 61805.00/ha with benefit cost ratio of 1.45) was found in T3 followed by T2 (Tk.1339.00/ha with benefit cost ratio of 1.01) and T1 (Tk. 201.50/ha with benefit cost ratio of 1.00).DOI: http://dx.doi.org/10.3329/pa.v19i1.17360 Progress. Agric. 19(1): 97 - 104, 2008

Living on the edge: a longitudinal study of Anopheles funestus in an isolated area of Mozambique

BackgroundUnderstanding the survival strategies of malaria vectors at the edges of their distribution, where they are under stress from environmental conditions, may lead to the development of novel control techniques and may help predict the effects of climate change on these mosquitoes.MethodsThe population dynamics of an isolated population of Anopheles funestus from the peninsula of Linga Linga in southern Mozambique was studied over a period of 104 weeks from March 2009 to May 2011 by 917 light-trap and 390 exit collections, mostly in an area close to a seasonal pond.ResultsOver the sampling period, 3,684 An. funestus females were caught. Densities decreased with increasing distance from the pond. In 2009 and 2010, a single annual peak in An. funestus density coincident with the single annual peak in rainfall was observed, but a clear population peak was absent during the first 21 weeks of 2011. In between population peaks, An. funestus remained present at low densities. In light trap collections, the proportion of gravid mosquitoes was significantly higher during the ‘low season’ (the period between peaks) than during the peak season (RR = 4.3, p<0.001). In contrast, in exit collections, the proportion of gravid mosquitoes was significantly lower during low season than during the peak season (RR = 0.64, p<0.01). Also, in light traps, the proportion of part-fed females was higher during the low season than during the peak season (RR = 4.5, p<0.001), whereas this was inversed for engorged females (RR = 0.46, p<0.05).Thirteen out of 289 (4.5%) An. funestus tested positive in the sporozoite ELISA. The proportion of sporozoite positive females was higher during the low season (6.25%, six out of 96) than during the peaks (3.63%, seven out of 193), but this difference was not significant.ConclusionsIt is suggested that a proportion of the mosquito population may become gonotrophically discordant during the long dry season resulting in enhanced mosquito survival and sustained malaria transmission.

The Link Between Environmental Variation and Evolutionary Shifts in Dormancy in Zooplankton

Sex and dormancy are intertwined in organisms that engage in asexual and sexual reproduction. The transition between asexual and sexual reproduction typically results in a dormant stage that provides a mechanism for persisting under harsh environmental conditions. For example, many zooplankton engage in sexual reproduction when environmental conditions deteriorate and produce resting eggs that remain viable for decades. It has long been assumed that observed variation in the timing and magnitude of investment into a dormant stage among populations or species reflects local environmental conditions. Yet, the importance of dormancy for the persistence of a given population can differ dramatically among habitats (i.e., permanent vs. seasonal ponds). As a result, environmental conditions may exert selection on the propensity for zooplankton to engage in sexual reproduction and enter dormancy in natural populations. Here, I highlight a growing body of research illustrating an important link between environmental conditions and divergent reproductive strategies in zooplankton. I specifically: (1) review the environmental cues that initiate a transition between asexual and sexual reproduction in zooplankton and (2) describe recent work demonstrating an evolutionary consequence of ecological selective pressures, such as predation and habitat predictability, on variation in the extent to which organisms engage in sex and enter dormancy. Such results have implications for the genetics and ecology of these organisms.

Invertebrate Community Patterns in Seasonal Ponds in Minnesota, USA: Response to Hydrologic and Environmental Variability

Seasonal ponds are common throughout forested regions of the north central United States. These wetlands typically flood due to snow-melt and spring precipitation, then dry by mid-summer. Periodic drying produces unique fishless habitats with robust populations of aquatic invertebrates. A basin’s physical/chemical features, the absence of vertebrate predation, and especially the duration of seasonal flooding, have long been viewed as the major structuring influences on these communities, but previous studies have shown only limited effects of environmental variables on pond invertebrates. Applying ordination methods to data from weekly collections of invertebrates during 2008–2009, we tested influences of site-level environmental gradients on the presence and relative abundance of aquatic invertebrate communities in 16 seasonal ponds in a forested region of north central Minnesota, USA. We assessed invertebrate community patterns in relation to pond size and depth, soil nutrients, canopy closure, hydroperiod, and predominant groundwater function (recharge, discharge, or flow-through). Patterns in pond invertebrate community composition were consistently related to pond depth, overhead canopy closure, and hydroperiod. Site-level hydrologic function showed weak relationships to seasonal patterns of invertebrate abundance. Although physical features of ponds had only modest influence on presence and abundance of invertebrates, weekly sampling improved models relating environmental variables to pond invertebrates.

Diversity of Rotifers of Rajapalayam Taluk, Virudhunagar District, Tamil Nadu, India

A study on the diversity of rotifers was carried out in seasonal and perennial ponds of Rajapalayam taluk, Virudhunagar district, for a period of 8 months from July 2007 to February 2008. During the study, 45 species of rotifers belonging to 10 families were documented. Among the 45 species, 11 are new records for the state and the recording of Brachionus donneri after its first description from the state is noteworthy.

Laboratory germination and seed bank storage of Ranunculus peltatus subsp. baudotii seeds from the Tuscan Archipelago

Germination requirements and suitability for ex situ conservation were investigated for seeds from the only population of Ranunculus peltatus Schrank subsp. baudotii (Godron) Meikle ex C.D.K. Cook (Ranunculaceae) from the Tuscan Archipelago (Italy). A 2 × 2 × 3 factorial experiment investigated the interactive effects of light, alternating temperatures and mean temperature on the germination of seeds sown on agar. Logistic regression analysis showed significant effects of both temperature (P < 0.0001) and light (P < 0.05). Alternating temperatures improved germination but only at mean temperatures of 20 and 15°C. The results indicate that seeds of R. baudotii exhibit morphological dormancy and a phenological adaptation to seasonal ponds. Drying led to a significant reduction in germination in seeds collected in both 2009 and 2010 (P < 0.05); the reduction was larger for 2009. The better quality of the 2010 seed was probably due to a post-harvest treatment that enabled continued maturation of the seeds. Storage of seeds for one year under seed bank conditions (-20°C) did not reduce viability. Seeds of R. baudotii possess orthodox storage behaviour and are therefore suited to ex situ conservation in seed banks; however, further research is needed to confirm their long term storage prospects.

Annual fish: developmental adaptations for an extreme environment

Annual fish are freshwater teleosts found in South America and Africa that are exposed to an extremely variable environment. They develop and reproduce in seasonal ponds that dry during the summer eliminating the entire adult population. Remarkably, desiccation-resistant embryos survive in these dry ponds that hatch during the next rainy season when the ponds are recreated. Among vertebrates, they represent one of the most remarkable extremophiles. They share several features with other fish models; however, they exhibit unique traits related to their peculiar life cycle. Epiboly is temporally and spatially uncoupled from organogenesis, and the embryos can undergo reversible developmental arrests (diapauses). These attributes make them a useful model to study diverse topics in developmental biology using a comparative and evolutionary approach. In this article, different aspects related to annual fish biology, taxonomy and phylogenetic considerations, reproductive strategy, and developmental characteristics with special focus on arrests, are summarized. The current challenge is to document and determine the factors that generate such high diversity and unique adaptations of annual fish. To understand this complexity, interdisciplinary approaches are being employed taking into consideration evolutionary biology, ethology, reproductive strategies, regulation of developmental mechanisms, and senescence.

An investigation into occasional White Spot Syndrome Virus outbreak in traditional paddy cum prawn fields in India.

A yearlong (September 2009–August 2010) study was undertaken to find out possible reasons for occasional occurrence of White Spot Syndrome Virus (WSSV) outbreak in the traditional prawn farms adjoining Cochin backwaters. Physicochemical and bacteriological parameters of water and sediment from feeder canal and four shrimp farms were monitored on a fortnightly basis. The physicochemical parameters showed variation during the two production cycles and between the farms studied. Dissolved oxygen (DO) content of water from feeder canal showed low oxygen levels (as low as 0.8 mg/L) throughout the study period. There was no disease outbreak in the perennial ponds. Poor water exchange coupled with nutrient loading from adjacent houses resulted in phytoplankton bloom in shallow seasonal ponds which led to hypoxic conditions in early morning and supersaturation of DO in the afternoon besides considerably high alkaline pH. Ammonia levels were found to be very high in these ponds. WSSV outbreak was encountered twice during the study leading to mass mortalities in the seasonal ponds. The hypoxia and high ammonia content in water and abrupt fluctuations in temperature, salinity and pH might lead to considerable stress in the shrimps triggering WSSV infection in these traditional ponds.

Records of Diatoms and Physicochemical Parameters of Seasonal Ponds in Zaria- Northern Nigeria

A study of diatoms species composition, associated with four ponds in Zaria, Northern Nigeria was carried out between November 2005–January 2006 and June–August 2006. Twenty three taxa of diatoms were recorded in the study. Multivariate analysis showed that there were significant positive and negative relationships (P < 0.05) between some physicochemical parameters and diatom species in these ponds. CCA results showed that Synedra and Actinocyclus were closely associated with TDS, DO and water hardness; Nitzschia, Frustulia, Navicula and Coscinodiscus with NO-N and alkalinity; and Cyclotella , Tabellaria and Achnanthes with phosphate phosphorus 3 levels.

Leaf Diet Affects Growth of a Shredder,Limnephilus indivisus, from a Seasonal New England Pond

Deciduous leaf litter is often a primary source of energy at the base of the food web in seasonal woodland ponds (e.g., vernal or autumnal pools), which are common in the northeastern United States. It is therefore important to understand how leaf diet af- fects growth of detritivores, such as the caddisfl y Limnephilus indivisus Walker, that feed almost exclusively on submerged plant matter in seasonal pond systems. Growth may relate to how rapidly a caddisfl y is able to complete its larval development and pupate, and hence its ability to survive in small ponds with short hydroperiods. Growth is also related to the maximum size the larva achieves. In many organisms, attaining a larger size conveys several distinct advantages: larger individuals typically have higher survival rates and increased fecundity, and hence greater fi tness compared to smaller conspecifi cs or competing sympatric species. To assess how leaf diet infl uences the growth of larvae of L. indivisus, we conducted a controlled experiment to test how different leaf diets in- fl uenced larval growth. The leaf diet experiment was set up as follows: Treatment 1: Acer rubrum (Red Maple), Treatment 2: Quercus spp. (oak), and Treatment 3: Red Maple and oak. L. indivisus that were fed oak leaves or a mix of oak and Red Maple leaves grew signifi cantly larger than larvae fed Red Maple leaves only. In Treatment 3, the caddisfl y was observed more frequently on the oak leaf compared to the Red Maple leaf. Although L. indivisus selected oak leaves more often during the experiment, oak leaves were less abundant than maple leaves at our study site. We hypothesize that the oak leaves provide more nutrients to L. indivisus due to a combination of physical, biological, and chemical properties which results in more larval growth.

BOLSA CHICA WETLANDS RESTORATION INLET DESIGN

Bolsa Chica Wetlands is one of a few recently restored large wetlands in Southern California of the United States. The project required restoration of tidal flooding of some isolated wetlands while minimizing impacts to the shoreline adjacent to the new inlet and maintenance costs, preserving endangered species on site, and maintaining oil field operations along the periphery of the project. The project created a direct connection to the ocean through wetland basins that included a full tidal basin, muted tidal basins and seasonal ponds linked by a series of ocean jetties, levees, water control structures, culverts, and channels. The inlet is a key project feature and has been the focus of numerous technical studies and numerical modeling tasks. As part of theses analyses, a pre-filled ebb bar was designed and about 1 million cubic yards of clean sand from the lowlands dredging was placed offshore to minimize the anticipated impacts of the inlet opening to the shoreline. This paper presents the inlet location selection, inlet and wetland hydrodynamics, inlet dimension optimization, inlet stability analyses, and jettied inlet entrance design. It also discusses findings of comparison between model predictions and field measurements of tidal elevations and sediment accumulations in the wetland basin since the completion of the project in August 2006. This project received the first Project Excellence Award from COPRI (Coasts, Oceans, Ports and Rivers Institute) of the American Society of Civil Engineers in 2008.