First attempts towards the restoration of gorgonian populations on the Mediterranean continental shelf

1. In the Mediterranean Sea, gorgonians are among the main habitat‐forming species of benthic communities on the continental shelf and slope, playing an important ecological role in coral gardens.
2. In areas where bottom trawling is restricted, gorgonians represent one of the main components of trammel net bycatch. Since gorgonians are long‐lived and slow‐growing species, impacts derived from fishing activities can have far‐reaching and long‐lasting effects, jeopardizing their long‐term viability. Thus, mitigation and ecological restoration initiatives focusing on gorgonian populations on the continental shelf are necessary to enhance and speed up their natural recovery.
3. Bycatch gorgonians from artisanal fishermen were transplanted into artificial structures, which were then deployed at 85 m depth on the outer continental shelf of the marine protected area of Cap de Creus (north‐west Mediterranean Sea, Spain). After 1 year, high survival rates of transplanted colonies (87.5%) were recorded with a hybrid remotely operated vehicle.
4. This pilot study shows, for the first time, the survival potential of bycatch gorgonians once returned to their habitat on the continental shelf, and suggests the potential success of future scaled‐up restoration activities.

     

DNA‐analysis to monitor fisheries and aquaculture: Too costly?

Evidence from DNA‐analysis is commonplace in human criminal investigations, and while it is increasingly being used in wildlife crime, to date, its application to control and enforcement activities in fisheries and aquaculture has only been sporadic. Contemporary DNA‐analysis tools are capable of addressing a broad range of compliance issues, species identification, mislabelling of fish products, determining the origin of catches and the farm of origin of aquaculture escapees. Such applications have the potential to ensure traceability along the fish product supply chain and to combat consumer fraud and Illegal, Unreported and Unregulated fishing. Nevertheless, DNA‐analysis is not yet used routinely in investigations into compliance with fisheries and aquaculture legislation. One potential reason for this is that DNA‐analysis techniques may have been regarded as too expensive. However, costs have plummeted over the past decade prompting us to objectively assess whether the costs associated with routine use of DNA‐analysis techniques for fisheries and aquaculture control and enforcement activities do constitute an impediment. Based on a number of recent fisheries and aquaculture compliance investigations that incorporated DNA‐analysis, our results indicate that the use of genetic analysis was justified and worthwhile in all cases examined. We therefore conclude that the costs associated with DNA‐analysis do not represent a barrier to the routine adoption of DNA‐analysis techniques in fisheries and aquaculture compliance investigations. Thus, control and enforcement agencies should be encouraged to use such techniques routinely.     

Response of winter root starch concentration to severe water stress and fruit load and its subsequent effects on early peach fruit development

Effect of water stress during stage III of peach fruit development on winter root starch concentration (RSC) and subsequent reproductive development was studied. Two irrigation treatments were applied in two consecutive seasons (2003-2004): full irrigation (FI) and no irrigation during stage III of fruit development until visible leaf wilting (LWI), which occurred when midday stem water potential reached -1.80 MPa. Three fruit thinning intensities were applied within each irrigation treatment. The year 2005 was a recovery year in which all trees received full irrigation and commercial fruit thinning. Water deficit and high fruit loads in the previous season significantly reduced the concentration of winter RSC. Fruit set and fruit growth from full bloom to 30 days after full bloom (30 DAFB) increased with increasing winter RSC before other factors, such as inter-fruit competition and availability of carbon from current photosynthesis, came into play. Consequently, severe water stress reduced the total number of fruits and fruit dry mass growth 30 DAFB. However, during the recovery year and after fruit thinning, fruit loads were similar between irrigation treatments and yield capacity remained unaffected. Peach fruit production recovered quickly from the deleterious effects of two consecutive years of water stress because of a combination of two factors: (1) reduced initial fruit set that was still adequate to achieve a commercial crop; and (2) the low sensitivity of fruit growth 30 DAFB to winter RSC.     

Factors involved in alleviating water stress by partial crop removal in pear trees

We studied the relief of water stress associated with fruit thinning in pear (Pyrus communis L.) trees during drought to determine what mechanisms, other than stomatal adjustment, were involved. Combinations of control irrigation (equal to crop water use less effective rainfall) and deficit irrigation (equal to 20% of control irrigation), fruit load (unthinned and thinned to 40 fruits per tree) and root pruning (pruned and unpruned) treatments were applied to pear (cv. 'Conference') trees during Stage II of fruit development. Daily patterns of midday stem water potential (Psi(stem)) and leaf conductance to water vapor (g(l)) of deficit-irrigated trees differed after fruit thinning. In response to fruit thinning, gl progressively declined with water stress until 30 days after fruit thinning and then leveled off, whereas the effects of decreased fruit load on Psi(stem) peaked 30-40 days after fruit thinning and then tended to decline. Soil water depletion was significantly correlated with fruit load during drought. Our results indicate that stomatal adjustment and the resulting soil water conservation were the factors determining the Psi(stem) response to fruit thinning. However, these factors could not explain differences in daily patterns between g(l) and Psi(stem) after fruit thinning. In all cases, effects of root pruning treatments on Psi(stem) in deficit-irrigated trees were transitory (Psi(stem) recovered from root pruning in less than 30 days), but the recovery of Psi(stem) after root pruning was faster in trees with low fruit loads. This behavior is compatible with the concept that the water balance (reflected by Psi(stem) values) was better in trees with low fruit loads compared with unthinned trees, perhaps because more carbon was available for root growth. Thus, a root growth component is hypothesized as a mechanism to explain the bimodal Psi(stem) response to fruit thinning during drought.     

Effect of drought on diameter increment of Quercus ilex, Phillyrea latifolia, and Arbutus unedo in a holm oak forest of NE Spain

The present study was carried out to elucidate the drought growth responses of Quercus ilex L., Phillyrea latifolia L., Arbutus unedo L., and other accompanying woody species of the Mediterranean holm oak forest. We submitted holm oak forest stands in Prades mountains (NE Spain) to a 2-year experimental drought. We reduced soil water availability about 15% by plastic strips and funnels that partially excluded rain throughfall and by ditch interception of water runoff. Mean stem diameter increment showed a great variation depending on the species. A. unedo had larger growth rates than Q. ilex and P. latifolia, but it was also the species that experimented the highest growth reduction in the drought plots (77%), suggesting a higher drought sensitivity than Q. ilex (55%) and P. latifolia (no drought effect). The growth reduction was specially marked in the larger trees. Aboveground stand biomass increment, estimated from stem diameter by allometric relationships, was 1.9 Mg ha⁻¹ per year in the control plots. The 15% reduction in the upper soil moisture produced 42% reduction in this biomass increment. In the drier conditions predicted in this Mediterranean area in the frame of climate change, an important reduction of growth rates can be hence expected, accompanied by a gain of dominance of drought-tolerant species such as P. latifolia in detriment of more mesic species such as Q. ilex.     

Seasonal patterns of root-surface phosphatase activities in a Mediterranean shrubland. Responses to experimental warming and drought

Mediterranean ecosystems are water limited and the current general circulation Models (GCM) and ecophysiological models forecast a warming and a further increase of drought in the next decades. A stronger water stress can decrease the capacity for nutrient absorption by plants. We conducted a field experiment to simulate forecasted drought and warming in a Mediterranean calcareous shrubland to assess the performance of root-surface phosphatase activities of the dominant shrub Globularia alypum. These enzyme activities were higher in autumn and spring, when the climate conditions were optimal for plant activity, than in summer or winter, when there was either lack of water or cold temperatures. A decrease in soil moisture in drought plots decreased root-surface phosphatase activity (29% in summer and 25% in autumn). The decrease in root-surface phosphatase activity in drought plots coincided with a decrease in P leaf concentrations and P accumulation in aboveground biomass and loss of photosynthetic capacity of some dominant shrub species of this ecosystem, and with a tendency to increase total soil-P. These results suggest that the expected drier conditions in this Mediterranean shrubland in the next decades will slow down the P uptake by plants, thereby, diminishing the P contents in biomass and increasing total P contents in soil in non-available forms and that this can be, in part, attributable to a result of the decrease in root-surface phosphatase activity.     

Preharvest calcium sprays improve volatile emission at commercial harvest of 'Fuji Kiku-8' apples

Apple (Malus × domestica Borkh.) fruit intended for long-term storage are frequently harvested commercially before becoming fully ripe, often resulting in poor aroma development. Since postharvest calcium dips have proved effective for the enhancement of flavor-related volatile esters after cold storage of apples, this study was undertaken in order to assess whether preharvest calcium sprays (7 weekly applications at 1.6%, w/v, 81-123 days after full bloom) could also aid in improving this important attribute at harvest. This procedure significantly increased calcium content in treated fruit. The emission of aroma-related volatile esters by untreated and calcium-treated 'Fuji' apples was then monitored during maturation and ripening over two months prior to commercial harvest. Results indicate that most of the compounds contributing to overall flavor in ripe fruit were enhanced in response to preharvest calcium applications, suggesting that this procedure may be suitable for the improvement of fruit aroma at harvest. The emission of acetate esters was particularly favored, consistent with higher acetaldehyde contents in treated fruit. These effects arose apparently from increased pyruvate decarboxylase (PDC) and alcohol dehydrogenase (ADH) activities, possibly leading to a better supply of alcohols and acyl CoAs for ester biosynthesis.     

A survey of Lolium rigidum populations in citrus orchards: Factors explaining infestation levels

The presence of herbicide‐resistant Lolium rigidum in Mediterranean (Spanish) citrus orchards was reported in 2005 and it poses a serious threat to crop management. The main objective of this research was to investigate which components could be responsible for the persistence of annual ryegrass populations in Mediterranean mandarin and orange orchards. This is the first study regarding L. rigidum populations in Mediterranean citrus orchards. Surveys were conducted in 55 commercial citrus orchards in eastern Spain in 2013 by interviewing technicians who were working in cooperatives about crop management. The level of infestation by L. rigidum and the presence of harvester ants (Messor barbarus) then were estimated in the same orchards. The variables were subjected to a two‐dimensional analysis and both univariate and multivariate logistic regression models were fitted for each of the three L. rigidum density levels that had been established. The multivariate models showed the significant factors that were associated with various L. rigidum densities: (i) at a low density, the herbicides that were applied, the number of applications in 2013 and the type of irrigation (flood or drip); (ii) at a medium density, the presence of harvester ants; and (iii) at a high density, the herbicides that were applied in 2013. The results indicated that drip irrigation and one application of glyphosate mixed with other herbicides (or herbicides other than glyphosate) were associated with a lower L. rigidum density. The alternative management options that are presented here should help farmers to reduce weed problems in Mediterranean citrus orchards. Future research is required to better understand the presence of herbicide‐resistant populations, as well as the possible beneficial presence of granivorous ant species.