Proposal for new quantitative eco-design indicators: a first case study

Eco-design is a valuable approach in order to reduce the environmental impact associated with a product system, by introducing environmental considerations early on in its design. Different strategies are possible for the implementation of eco-design, depending on the intended goals as well as the characteristics of the products. The present work proposes a series of eco-design indicators and tests to what extent the application of these simple indicators provides a reliable indication of the reduction of environmental impact, as measured by commonly employed Life Cycle Impact Assessment (LCIA) indicators. The product chosen for the case study was a water source heat pump. Two of the newly-developed indicators were applied and compared to LCIA indicators, focussing on design for disassembly and for recycling. A good and robust correlation was found, providing support to the thesis that these simple eco-design indicators can be used as a proxy to quickly and effectively gauge the environmental improvements introduced in a product system at the design stage.     

Comparative survival of bay scallops in eelgrass and the introduced alga, Codium fragile, in a New York estuary

Eelgrass, Zostera marina, is generally regarded as the preferred habitat of bay scallops, but in some cases scallop populations have persisted or increased in areas lacking eelgrass. This suggests that some other substrate(s) may serve important ecological functions for bay scallops. One candidate is Codium fragile, a macroalgal species with which bay scallops are known to associate and in which we commonly find juvenile and adult bay scallops in eastern Long Island, New York. In this study, we examined whether survival of planted bay scallops differed in Codium, eelgrass, and Codium + eelgrass substrates at two sites during August and October of 2 years. Survival of tethered scallops and recoveries of live free-planted individuals varied with scallop size, planting season and year, but no differences were observed between the three substrates for a given scallop size and planting date. Crab (particularly Dyspanopeus sayi) and whelk predation were implicated as important causes of tethered scallop mortalities while emigration and removal by predators likely contributed to scallop losses. Densities of naturally recruited 0+ years scallops recovered by visual and suction dredge sampling were similar in the eelgrass and Codium substrates. While our results suggest that Codium may offer some degree of predation refuge for bay scallops, further work needs to weigh the potential disadvantages of this substrate (such as low DO levels, potential attachment and transport of scallops, and differences in current flow, food availability and sedimentation relative to eelgrass) to determine if Codium may serve as a valuable habitat for bay scallops throughout their lifespan.     

Modelling the effects of extreme events on the dynamics of the amphipod Corophium orientale

The brackish water amphipod Corophium orientale is the dominant macroinvertebrate species in the upper Mira estuary, a small mesotidal system located in the southwest coast of Portugal. As climate changes will increase the frequency and intensity of extreme events such as floods and droughts, these will have a negative effect on benthic estuarine invertebrates, namely C. orientale. In order to understand the effects of these events on C. orientale, a dynamic model, based on published information and calibrated with field data, was developed and different scenarios were tested.For model construction, the annual development of three cohorts of C. orientale, their growth rates, and the establishment of the timing of each cohort rise and extinction are introduced. This structure can be repeated indefinitely, for years, and few parameters are required. The model simulations highlight the need for refuge areas that enable a fast recovery of the amphipod population after an extreme event and the recolozination of the affected areas.     

Mercury removal using ground and calcined mussel shell

We determined mercury retention on calcined and ground mussel shell, in presence and absence of phosphate, using batch and stirred flow chamber experiments. In batch experiments the calcined shell exhibited higher Hg adsorption, with good fitting to Freundlich equation （R^2： 0.925-0.978）; the presence of phosphate increased Hg adsorption; mercury desorption was 13% or lower, diminishing up to 2% under the presence of phosphates. In stirred flow chamber experiments calcined shell retained more Hg than ground shells （6300 vs. 4000-5200 μmol/kg）; Hg retention increased an additional 40% on calcined shell and up to an additional 70% on ground shells when phosphates were present; mercury desorption was quite similar in all shell types （20%-34%）, increasing up to 49%-60% in ground shells when phosphates were present. The higher Hg adsorption on calcined shell would be related to its calcite and dolomite concentrations; mercury-phosphate interactions would cause the increase in Hg retention when phosphates are present. Data on Hg desorption suggest that Hg retention was not easily reversible after batch experiments, increasing in the stirred flow chamber due to convective flow. Calcined and ground mussel shells could be recycled removing Hg from water, with the presence of phosphates in solution improving efficacy.     

Travel duration,energetic expenditure,and patch exploitation in the parasitic wasp <Emphasis Type="Italic">Venturia canescens</Emphasis>

Foraging animals usually keep track of how costly it is to reach new resource patches and adjust patch residence time and exploitation rate accordingly. There are at least two potential factors, which are not necessarily closely linked, that animals could measure to estimate costs of traveling: the time the forager needs to reach the next patch and the amount of energy it has to invest until arrival. In the parasitoid wasp Venturia canescens, females forage for hosts from which their offspring can develop. Two different types of this parasitoid exist. The thelytokous type lives in anthropogenic habitats where flight is not necessarily linked with foraging. The arrhenotokous type lives under field conditions and shows frequent flight activity. We tested whether the wasps would use time or energy needed to assess patch availability, by either confining them into vials or letting them travel actively in a flight mill between patch visits. Our results show that in thelytokous lines, time is a sufficient cue influencing patch exploitation and an additional effect of the energy needed was not visible. In the arrhenotokous wasps, however, only the number of rounds flown in the mill influenced subsequent behavior, while mere time spent traveling did not. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Differential use of conspecific-derived information by sexual and asexual parasitic wasps exploiting partially depleted host patches

When foraging partially depleted patches (i.e., a fraction of hosts are already parasitized), female parasitoids must decide: 1—whether to superparasitize, and 2—whether to stay in their current patch (thus missing the opportunity of finding a better patch elsewhere). To make these decisions, parasitoids may rely on different cues, produced both by the environment and by conspecifics. Animals thriving in different environments may differ in cues they use. In the solitary parasitoid Venturia canescens, thelytokous (asexual) and arrhenotokous (sexual) individuals are found in two contrasting environments. Thelytokous females, from anthropogenic conditions, are known to cope with superparasitism in an adaptive way. On the other hand, little is known about superparasitism by arrhenotokous females. We compared the host exploitation strategies of thelytokous and arrhenotokous females in partially depleted patches. Hosts parasitized by thelytokous females were more frequently avoided than those parasitized by arrhenotokous females, suggesting a stronger chemical marking of the former. Only thelytokous females used information from conspecifics for patch-leaving decisions. The conformity of the differences in the behavior of thelytokous and arrhenotokous females with the environmental conditions they experience in their habitat is discussed.     

Reproduction and imposex in the edible snail <Emphasis Type="Italic">Adelomelon ancilla</Emphasis> from northern Patagonia,Argentina

The edible volutid snail Adelomelon ancilla occurs on the Argentine coast and may have the capacity to serve as source of support for local fisheries. However, knowledge of its reproduction is lacking. Over 3 years (from September 2000 to July 2004) we studied the oviposition at Golfo Nuevo, Patagonia by diving. Monthly collections were performed to examine gonadal stages histologically during 2002–2003. Gamete development stages corresponded with the expected period for oviposition occurring from July to November, a time of increasing day length. Oviposition also took place in March when water temperature attained a maximum of 18°C. Following the spawning period, remaining gametes were resorpted in both sexes. Males contained sperm throughout the year, parasperm and eusperm forms were found within the same acinus. Oogonia/oocytes ranged from 20 to 240 μm in diameter during oogenesis. Females commenced laying egg capsules from a shell length of 114 mm. Reproduction is compared with other fishable volutid snails from the Argentine shelf, and suggests the need to apply certain fishing restrictions if the resource begins to be utilized commercially. The imposex condition was found in snails from some shipping areas. The frequency of this condition declined with distance from the port.