Jonathan C. P. Reum

First Record Of An Albino Chimaeriform Fish, Hydrolagus colliei

HAZLITT SL, GASTON AJ. 2003. Black Oystercatcher natal philopatry in the Queen Charlotte Islands, British Columbia. Wilson Bulletin 114:520–522. NYSEWANDER D. 1977. Reproductive success of the Black Oystercatcher in Washington state [thesis]. Seattle, WA: University of Washington. 71 p. SULLIVAN TM, HAZLITT SL, LEMON MJF. 2003. Population trends of nesting Glaucous-winged Gulls, Larus glaucescens, in the southern Strait of Georgia, British Columbia. Canadian Field-Naturalist 116:564–567. VERMEER K, MORGAN KH., SMITH GEJ. 1989. Population and nesting habitat of American Black Oystercatchers in the Strait of Georgia. In: Vermeer, K and Butler RW, editors. The ecology and status of marine and shoreline birds in the Strait of Georgia, British Columbia. Ottawa, ON: Occasional Paper Number 75, Canadian Wildlife Service. p 118–122. VERMEER K, EWINS P J, MORGAN KH, SMITH GEJ. 1992. Population and nesting habitat of American Black Oystercatchers on the west coast of Vancouver Island. In: Vermeer K, Butler RW, editors. The ecology and status of marine and shoreline birds on the west coast of Vancouver Island. Ottawa, ON: Occasional Paper 75, Canadian Wildlife Service. p 65–70. WOOTTON JT 1992. Indirect effects, prey susceptibility, and habitat selection: impacts of birds on limpets and algae. Ecology 73:981–991.

Implications of scaled δ15N fractionation for community predator–prey body mass ratio estimates in size‐structured food webs

Nitrogen stable isotope ratios (δ(15) N) may be used to estimate community-level relationships between trophic level (TL) and body size in size-structured food webs and hence the mean predator to prey body mass ratio (PPMR). In turn, PPMR is used to estimate mean food chain length, trophic transfer efficiency and rates of change in abundance with body mass (usually reported as slopes of size spectra) and to calibrate and validate food web models. When estimating TL, researchers had assumed that fractionation of δ(15) N (Δδ(15) N) did not change with TL. However, a recent meta-analysis indicated that this assumption was not as well supported by data as the assumption that Δδ(15) N scales negatively with the δ(15) N of prey. We collated existing fish community δ(15) N-body size data for the Northeast Atlantic and tropical Western Arabian Sea with new data from the Northeast Pacific. These data were used to estimate TL-body mass relationships and PPMR under constant and scaled Δδ(15) N assumptions, and to assess how the scaled Δδ(15) N assumption affects our understanding of the structure of these food webs. Adoption of the scaled Δδ(15) N approach markedly reduces the previously reported differences in TL at body mass among fish communities from different regions. With scaled Δδ(15) N, TL-body mass relationships became more positive and PPMR fell. Results implied that realized prey size in these size-structured fish communities are less variable than previously assumed and food chains potentially longer. The adoption of generic PPMR estimates for calibration and validation of size-based fish community models is better supported than hitherto assumed, but predicted slopes of community size spectra are more sensitive to a given change or error in realized PPMR when PPMR is small.

Using Conceptual Models and Qualitative Network Models to Advance Integrative Assessments of Marine Ecosystems

ABSTRACT The complexity of ecosystem-based management (EBM) of natural resources has given rise to research frameworks such as integrated ecosystem assessments (IEA) that pull together large amounts of diverse information from physical, ecological, and social domains. Conceptual models are valuable tools for assimilating and simplifying this information to convey our understanding of ecosystem structure and functioning. Qualitative network models (QNMs) may allow us to conduct dynamic simulations of conceptual models to explore natural–social relationships, compare management strategies, and identify tradeoffs. We used previously developed QNM methods to perform simulations based on conceptual models of the California Current ecosystems pelagic communities and related human activities and values. Assumptions about community structure and trophic interactions influenced the outcomes of the QNMs. In simulations where we applied unfavorable environmental conditions for production of salmon (Oncorhynchus spp.), intensive management actions only modestly mitigated declines experienced by salmon, but strongly constrained human activities. Moreover, the management actions had little effect on a human wellbeing attribute, sense of place. Sense of place was most strongly affected by a relatively small subset of all possible pair-wise interactions, although the relative influence of individual pair-wise interactions on sense of place grew more uniform as management actions were added, making it more difficult to trace effective management actions via specific mechanistic pathways. Future work will explore the importance of changing conceptual models and QNMs to represent management questions at finer spatial and temporal scales, and also examine finer representation of key ecological and social components.

Stable Isotope Applications for Understanding Shark Ecology in the Northeast Pacific Ocean

Stable isotopes are used to address a wide range of ecological questions and can help researchers and managers better understand the movement and trophic ecology of sharks. Here, we review how shark studies from the Northeast Pacific Ocean (NEP) have employed stable isotopes to estimate trophic level and diet composition and infer movement and habitat-use patterns. To date, the number of NEP shark studies that have used stable isotopes is limited, suggesting that the approach is underutilized. To aid shark researchers in understanding the strengths and limitations of the approach, we provide a brief overview of carbon and nitrogen stable isotope trophic discrimination properties (e.g., change in δ15N between predator and prey), tissue sample preparation methods specific to elasmobranchs, and methodological considerations for the estimation of trophic level and diet composition. We suggest that stable isotopes are a potentially powerful tool for addressing basic questions about shark ecology and are perhaps most valuable when combined and analysed with other data types (e.g., stomach contents, tagging data, or other intrinsic biogeochemical markers).

Species Composition and Relative Abundance of Large Medusae in Puget Sound, Washington

Abstract We assessed species composition and relative biomass densities of large medusae (bell diameters larger than 4 cm) at four locations in Puget Sound, Washington, over two sampling periods (June and September). We specifically sampled sites in southern Hood Canal (near Hoodsport), northern Hood Canal (Hazel Point), southern Admiralty Inlet (Useless Bay) and Possession Sound using a bottom trawl as part of a larger survey of demersal fish and invertebrate community structure. In total, four species were observed during June sampling: three schyphomedusae (Phacellophora camtschatica, Cyanea capillata, Aurelia labiata) and one hydromedusa (Aequorea victoria). The highest jellyfish densities in June were observed off Hoodsport where Aurelia labiata and Cyanea capillata dominated the assemblage. In the remaining locations, Cyanea capillata dominated catches. In September, relative biomass densities were lower throughout the area surveyed and species composition simplified with usually one species of jellyfish clearly dominating each location. Our results indicate that jellyfish biomass changed markedly within and among locations, which has implications for modeling energy flows in Puget Sound and developing monitoring schemes that are able to capture interannual variability in jellyfish biomass. Given the abundance of jellyfish in our survey and their potential as sentinels of change in the marine environment we recommend that jellyfish populations be routinely monitored in Puget Sound.