A new framework of spatial targeting for single-species conservation planning

Context

Organisations acting to conserve and protect species across large spatial scales prioritise to optimise use of resources. Spatial conservation prioritization tools typically focus on identifying areas containing species groups of interest, with few tools used to identify the best areas for single-species conservation, in particular, to conserve currently widespread but declining species.

Objective

A single-species prioritization framework, based on temporal and spatial patterns of occupancy and abundance, was developed to spatially prioritize conservation action for widespread species by identifying smaller areas to work within to achieve predefined conservation objectives.

Methods

We demonstrate our approach for 29 widespread bird species in the UK, using breeding bird atlas data from two periods to define distribution, relative abundance and change in relative abundance. We selected occupied 10-km squares with abundance trends that matched species conservation objectives relating to maintaining or increasing population size or range, and then identified spatial clusters of squares for each objective using a Getis-Ord-Gi* or near neighbour analysis.

Results

For each species, the framework identified clusters of 20-km squares that enabled us to identify small areas in which species recovery action could be prioritized.

Conclusions

Our approach identified a proportion of species’ ranges to prioritize for species recovery. This approach is a relatively quick process that can be used to inform single-species conservation for any taxa if sufficiently fine-scale occupancy and abundance information is available for two or more time periods. This is a relatively simple first step for planning single-species focussed conservation to help optimise resource use.

     

The release and uptake of metals from potential biofilm inhibition products during spiny lobster (Sagmariasus verreauxi,H. Milne Edwards 1851) culture

Zinc (Zn) and copper (Cu) are strong inhibitors of bacterial biofilms in aqueous solutions, but are known toxins of crustaceans. A new metal application method; cold‐sprayed metal embedment, known to modulate metal release, was tested for its applications in crustacean larval culture systems. Cold‐spray technology allows metal particles to bond to plastics, while modulating metal ion release and biocide activity to the substrate boundary. In this study, Eastern spiny lobster (Sagmariasus verreauxi) larvae (phyllosoma) were cultured in the presence of cold‐sprayed Zn and Cu metal surfaces. Metal loss was monitored gravimetrically on embedded surfaces, assessment of water ion concentrations and analysis of phyllosoma body content were undertaken. Phyllosoma moulting, deformity and mortality patterns were monitored. Cold‐sprayed Zn‐ and Cu‐embedded surfaces were depleted with losses of 0.69% and 31.2% noted respectively. Culture water concentrations of these metals were elevated and accumulation by phyllosoma occurred. Water Zn concentrations of 18.5 μg L^?1 were associated with chronic eyestalk moult deformities; the first report of Zn causing a non‐lethal moult deformity in crustacean larvae. The Cu surface lost a third of its metal mass with a water concentration of 40 μg L^?1 causing acute toxicity and localization of composite granules in the midgut gland. Cu associated mortality was noted by Day 2 of culture with a LD 50 experienced by Day 9. Future work on the use of bioactive metals in aquaculture systems will focus on a range of different metal alloys, and improved modulation of ion release mechanisms through increased particle embedment depth and separation.     

Short-term effects of aglime on inorganic- and organic-derived CO2 emissions from two acid soils amended with an ammonium-based fertiliser

Purpose

Aglime application can promote carbon dioxide (CO₂) emissions from acid soils. However, the controlling mechanisms are still poorly understood, particularly the role of fertiliser-ammonium oxidation. This study therefore assessed the effects of aglime on soil inorganic C (SIC)– and soil organic C (SOC)–derived CO₂ emissions from acid soils amended with ammonium.

Materials and methods

Ammonium at three N rates [0% (A0), 0.005% (A1), and 0.2% (A2) w/w] and labelled aglime (Ca¹³CO_3,¹³C 5.94% aa) at three rates [0% (L1), 0.067% (L1), and 0.392% (L2) w/w] were applied to two contrasting acid soils (Nariva series, Mollic Fluvaquents; and Piarco series, Typic Kanhaplaquults) and incubated in 1-l media bottles for 23 days. A calcareous soil (Princes Town series, Aquentic Eutrudepts, carbonate δ¹³C of ??4.79‰) was included as a control that only received ammonium at the three rates.

Results and discussion

The application of ammonium at the A2 rate significantly (p?<?0.05) increased cumulative SIC-CO₂ emissions by 15.8 and 27.1% in comparison to the A0 rate for the Nariva and Piarco soils, respectively, when they were limed at the L2 rate. The lower rate of ammonium (A1), however, had no effect on these emissions, which suggests that enough acidity may not have been generated at this rate to significantly enhance the release of SIC-CO₂. Furthermore, no effect of ammonium rates was observed on SIC-CO₂ emissions from the calcareous soil, which refutes the hypothesis that this amendment plays a greater role in regulating these emissions from calcareous soils compared with acid soils. Also, in contradiction to another hypothesis, the aglime-induced priming effect on SOC decomposition was more apparent in the low-C Piarco soil. This effect was also significantly (p?<?0.05) greater at the L2 rate (above the lime requirement for Piarco), which demonstrates the negative impact that over-liming could have on the sequestration of C in this soil. Our results also showed that ammonium addition may also help to reduce the magnitude of the aglime-induced priming effect in the Piarco soil when it is not over-limed.

Conclusions

Overall, the findings of this study suggest that ammonium fertiliser broadcast at conventional rates may not serve as a significant regulator of SIC-CO₂ emissions from highly to moderately acidic soils amended with aglime. Our findings also indicate a need to consider nitrogen management as an important factor regulating the effects of aglime on SOC-CO₂ emissions.

     

Evaluating the relationship between yearling walleye,Sander vitreus,electrofishing catch‐per‐unit‐effort and density in northern Wisconsin lakes

Recruitment declines of walleye, Sander vitreus (Mitchill), observed in some northern Wisconsin lakes have resulted in management actions to evaluate and rehabilitate populations. An effective index for estimating relative abundance of yearling walleye is required. The objectives herein were : (a) to evaluate the relationship between yearling walleye electrofishing CPUE and density in northern Wisconsin lakes; (b) to test for the influence of lake‐specific factors on electrofishing catchability of yearling walleye; and (c) to develop an index whereby electrofishing CPUE can be used to quantify yearling walleye relative abundance. Yearling density was significantly positively related to electrofishing CPUE on a long‐term dataset from Escanaba Lake as well as a dataset including several lakes combined. Electrofishing catchability of yearling walleye was negatively related to lake‐surface area but was not related to other lake‐specific variables. This index can provide an efficient method to continue monitoring natural recruitment and also to evaluate survival of stocked walleye.     

Preliminary assessment of large‐scale co‐culture of sandfish (Holothuria scabra) with the Babylon snail (Babylonia areolata) in earthen ponds and in raceways

Holothuria scabra (sandfish) and Babylonia areolata were trialed in two large‐scale co‐culture experiments. Experiment 1 assessed co‐culture in 4 × 400 m² earthen ponds where Babylonia were cultured in a central pen at a density of 400 individuals/m² with sandfish occupying the remaining pond space at 1.1 individuals/m². Sandfish grew from 18.20 ± 6.67 g to 119.03 ± 17.74 g in 92 days and Babylonia (fed trash fish in both experiments) grew from 0.90 ± 0.38 g to 4.93 ± 1.44 g, but Babylonia growth was not increased in co‐culture compared to monoculture. Water and sediment quality varied between co‐culture and monoculture ponds. Neither showed clear improvement due to sandfish culture. Experiment 2 compared non‐segregated sandfish‐Babylonia co‐culture with Babylonia monoculture in 20 m² concrete raceways. Sandfish were cultured at 2 individuals/m² and Babylonia at 300 individuals/m². Sandfish grew up to 1.91 g.day^?1 with 100% survival. Babylonia weight gain was significantly greater in co‐culture raceways (3.35 ± 0.64 g over 61 days), which was double that of Babylonia in monoculture. Substrate total N was reduced by 20% in co‐culture compared with monoculture (p = .032). This provisional study of commercial scale sandfish‐Babylonia co‐culture demonstrates culture compatibility, providing a basis for further system development.     

An assessment of subsoil organic carbon stocks in England and Wales

It is estimated that half the soil carbon globally is in the subsoil, but data are scarce. We updated estimates of subsoil organic carbon (OC) in England and Wales made by Bradley et al. (2005) using soil and land‐use databases and compared the results with other published data. We estimated that the soils of England and Wales contained 1633, 1143 and 506 Tg of OC at 0–30, 30–100 and 100–150 cm depths, respectively. Thus, half of the soil OC was found below 30 cm depth. Peat soils accounted for the largest proportion, containing 44% of all the OC below 30 cm despite their small areal extent, followed by brown soils, surface‐water gley soils, ground‐water gley soils and podzolic soils. Peat soils had more than 25% of their profile OC per unit area in the 100–150 cm depth, whereas most other soils had <8% at this depth. The differences between soil types were consistent with differences in soil formation processes. Differences in depth distributions between land uses were small, but subsoil OC stocks in cultivated soils were generally smaller than in soils under grassland or other land uses. Data on subsoil OC stocks in the literature were scarce, but what there was broadly agreed with the findings of the above database exercise. There was little evidence by which to assess how subsoil OC stocks were changing over time.     

Experimental Infections of Bluegill with the Trematode Ribeiroia ondatrae (Digenea: Cathaemasiidae): Histopathology and Hematological Response

Infections by the digenetic trematode, Ribeiroia ondatrae, cause severe limb malformations in many North American amphibians. Ribeiroia ondatrae also infects fishes as second intermediate hosts, but less is known about the pathology and immune responses initiated in infected fish, even though reports of infected fish date back to early 1900s. To this end, we experimentally exposed juvenile Bluegills Lepomis macrochirus to three doses of R. ondatrae cercariae and monitored the pathology, parasite infection success, and humoral responses over 648 h. All exposed fish became infected with metacercariae, and the average infection load increased with exposure dose. Histologically, infection was associated with acute hemorrhages in the lateral line and local dermis at 36 h, followed by progressive granulomatous inflammation that led to the destruction of encysted metacercariae. Correspondingly, over the course of 648 h we observed an 85% decline in average infection load among hosts, reflecting the host's clearance of the parasite. Infection was not associated with changes in fish growth or survival, but did correlate with leukocytosis and neutrophilia in circulating host blood. Understanding the physiological responses of R. ondatrae in Bluegill will help to clarify the ecological effects of this parasite and provide a foundation for subsequent comparisons into its effects on behavior, individual health, and population dynamics of Bluegill.

Received March 4, 2015; accepted August 9, 2015     

One-day rate measurements for estimating net nitrification potential in humid forest soils

Measurements of net nitrification rates in forest soils have usually been performed by extended sample incubation (2–8 weeks), either in the field or in the lab. Because of disturbance effects, these measurements are only estimates of nitrification potential and shorter incubations may suffice. In three separate studies of northeastern USA forest soil surface horizons, we found that laboratory nitrification rates measured over 1 day related well to those measured over 4 weeks. Soil samples of Oa or A horizons were mixed by hand and the initial extraction of subsamples, using 2 mol L⁻¹ KCl, occurred in the field as soon as feasible after sampling. Soils were kept near field temperature and subsampled again the following day in the laboratory. Rates measured by this method were about three times higher than the 4-week rates. Variability in measured rates was similar over either incubation period. Because NO₃⁻ concentrations were usually quite low in the field, average rates from 10 research watersheds could be estimated with only a single, 1-day extraction. Methodological studies showed that the concentration of NH₄⁺ increased slowly during contact time with the KCl extractant and, thus, this contact time should be kept similar during the procedure. This method allows a large number of samples to be rapidly assessed.