A Comparison of Predation Rates by Non-indigenous and Indigenous Crabs (Juvenile Carcinus maenas, Juvenile Cancer irroratus, and Adult Dyspanopeus sayi) in Laboratory and Field Experiments

Mean daily consumption rates on Mytilus spp. were compared among juveniles of the non-indigenous Carcinus maenas, juveniles of the indigenous Cancer irroratus, and adults of the indigenous Dyspanopeus sayi between June and August 2005 to assess the relative impact of juvenile C. maenas in field (Benacadie Channel (45°54′ N, 60°53′ E), Bras d’Or Lakes, Nova Scotia, Canada) and laboratory experiments. This study examined: (1) whether consumption rates in a field setting vary among species; (2) the effect of laboratory and field settings on species-specific consumption rates, and whether rates vary between settings for each species; and (3) the effects of temperature and salinity on the consumption rates of these species. In field experiments, there was no significant difference in consumption among C. maenas, C. irroratus, and D. sayi (0.100?±?0.067, 0.450?±?0.189, and 0.800?±?0.423 mussels crab^?1 d^?1, respectively). However, both C. maenas and C. irroratus consumed two to four times more prey in the laboratory than in the field. D. sayi prey consumption was also greater (although not significant) in the laboratory than in the field. In the laboratory, consumption rate was greater for C. irroratus in salinities of 26 than 17 (2.75 and 1.69–1.81 mussels crab^?1 d^?1, respectively), and in 17°C than 13°C (1.10–1.21 and 0.56–0.64 mussels crab^?1 d^?1, respectively) for C. maenas. In all experiments, consumption rates of juvenile C. maenas were lower than or similar to those of the juvenile and adult indigenous species, suggesting that the potential predatory impact of juvenile C. maenas on Mytilus spp. may not be as significant as that of the adults of this non-indigenous species.     

Multi‐year water balance assessment of a newly constructed wetland,Fort McMurray,Alberta

Oil sands mining in Alberta transforms the boreal landscape of forests and wetlands into open pits, tailings ponds and overburden piles. Whereas reclamation efforts have primarily focused on upland forests, rebuilding wetland systems has recently become a motivation for research. Wetland creation and sustainability in this region is complicated by the sub‐humid climate and salinity of underlying mining material. In 2012, Syncrude Canada Ltd. completed the construction of the Sandhill Fen Watershed (SFW), a 52‐ha upland‐wetland system to evaluate wetland reclamation strategies on soft tailings. SFW includes an active pumping system, upland hummocks, a fen wetland and underdrains. To evaluate the influence of management practices on the hydrology of the system, this study reports the water balance from January 2013 to December 2014, the first 2 years after commissioning. A semi‐distributed approach was taken to examine the fluxes and stores of water in uplands and lowlands. Natural and artificial inputs and outputs were measured using a series of precipitation gauges and pumps, and evapotranspiration was quantified using three eddy covariance towers. A series of near surface wells recorded water table position. Both 2013 and 2014 were normal rainfall years, with 2013 having more and 2014 less snow than normal. In 2013, inflow/outflow from pumping was the predominant hydrological fluxes, resulting in considerable variability in water table position and storage changes throughout the summer. In 2014, the artificial addition of water was negligible, yet the water table remained near the surface in lowland locations, suggesting that wetland conditions could be maintained under current conditions. Evapotranspiration rates between uplands and lowlands were similar between years and sites, ranging from 2.2 ± 1.8 to 2.5 ± 1.2 mm/day and were largely controlled by climate. These rates were less than nearby older upland systems, suggesting that water balance partitioning will change as vegetation develops. Comparison between years and with natural systems provides insight on how management practices influence hydrologic dynamics and the overall water balance of the SFW. Copyright © 2016 John Wiley & Sons, Ltd.     

Population structure of two deep sea tubeworms,Lamellibrachia luymesi and Seepiophila jonesi,from the hydrocarbon seeps of the Gulf of Mexico

Vestimentiferan tubeworms are a group of large sessile marine polychaete annelids (family Siboglinidae) found in the regions of hydrothermal venting or seepage of the reduced chemical hydrogen sulfide. Hydrocarbon seeps on the Louisiana Slope of the Gulf of Mexico support large communities of the co-occurring vestimentiferan species Lamellibrachia luymesi and Seepiophila jonesi. These sessile species have the opportunity to disperse between the patchy sites of active seepage on the seafloor during a planktonic larval stage. However, it is unclear whether dispersal occurs at a local or global scale. Four (L. luymesi) and seven (S. jonesi) microsatellite loci were used to test for population substructure among ten hydrocarbon seep sites on the Louisiana Slope. Both species showed high levels of allelic diversity, averaging 18.5 (L. luymesi) and 22 (S. jonesi) alleles/locus, respectively, and high observed heterozygosity at all microsatellite loci (0.71–0.9 in L. luymesi, 0.27–0.84 in S. jonesi). The two species showed a significant deficiency in heterozygotes compared to that predicted under the Hardy–Weinberg equilibrium. L. luymesi showed a small but significant amount of population structure, with a positive correlation between genetic and geographic distance among the sample sites spanning 540 km. S. jonesi, in contrast, showed no evidence for isolation by distance, but did show a significant genetic difference between aggregations of different ages. These results suggest that these two species differ in how larvae are able to colonize new seep sites through space (L. luymesi) and though time (S. jonesi).     

Guiding ecological principles for marine spatial planning

The declining health of marine ecosystems around the world is evidence that current piecemeal governance is inadequate to successfully support healthy coastal and ocean ecosystems and sustain human uses of the ocean. One proposed solution to this problem is ecosystem-based marine spatial planning (MSP), which is a process that informs the spatial distribution of activities in the ocean so that existing and emerging uses can be maintained, use conflicts reduced, and ecosystem health and services protected and sustained for future generations. Because a key goal of ecosystem-based MSP is to maintain the delivery of ecosystem services that humans want and need, it must be based on ecological principles that articulate the scientifically recognized attributes of healthy, functioning ecosystems. These principles should be incorporated into a decision-making framework with clearly defined targets for these ecological attributes. This paper identifies ecological principles for MSP based on a synthesis of previously suggested and/or operationalized principles, along with recommendations generated by a group of twenty ecologists and marine scientists with diverse backgrounds and perspectives on MSP. The proposed four main ecological principles to guide MSP—maintaining or restoring: native species diversity, habitat diversity and heterogeneity, key species, and connectivity—and two additional guidelines, the need to account for context and uncertainty, must be explicitly taken into account in the planning process. When applied in concert with social, economic, and governance principles, these ecological principles can inform the designation and siting of ocean uses and the management of activities in the ocean to maintain or restore healthy ecosystems, allow delivery of marine ecosystem services, and ensure sustainable economic and social benefits.     

Mesoproterozoic Fraser Complex: Geochemical evidence for multiple subduction‐related sources of lower crustal rocks in the Albany‐Fraser Orogen,Western Australia

The 1300 Ma Fraser Complex in the Albany‐Fraser Orogen of Western Australia is a thrust stack of mainly gabbroic rocks metamorphosed to granulite facies. This package of fault‐bounded units was elevated from a deep crustal level onto the margin of the Yilgarn Craton during continental collision between the Mawson and Yilgarn Cratons. Incompatible trace‐element distributions demand at least three mantle sources. Primitive‐mantle‐normalised incompatible‐element distributions show strong negative Ta–Nb anomalies, typical of subduction‐derived magmas. Three lines of evidence indicate that the mafic magmas did not acquire these anomalies by assimilation of crustal rocks: (i) major‐element compositions do not allow appreciable contamination with felsic material; (ii) Ni contents of many mafic rocks are too high for a significant contribution from a felsic assimilant; and (iii) Sr and Nd isotopic data support a largely juvenile source for the magmas that produced the Fraser Complex. Hence, the Ta–Nb anomalies are interpreted to reflect subduction‐related magmatic sources. On multielement diagrams, depletions in Sr, Eu, P, and Ti can be explained by fractional crystallisation, whereas Th and Rb depletions in many of the Fraser Complex rocks probably reflect losses during granulite‐facies metamorphism. These results suggest that the lower crust in this region at 1300 Ma was dominantly of arc origin, and there is no evidence to support mantle plume components. The Fraser Complex is interpreted as remnants of oceanic arcs that were swept together and tectonically interleaved with the margin of the Mawson Craton just before, or during, collision with the Yilgarn Craton at 1300 Ma.