Surrogate measures for assessing cryptic faunal biodiversity on macroalgal-dominated subtidal reefs

A major impediment to the identification of priority areas for marine biodiversity conservation is a fundamental lack of information about the distribution of many marine species. Comprehensive species inventories for many areas currently do not exist, and performing detailed taxonomic surveys is often prohibitively expensive and time-consuming. Accordingly, there is a need to develop simple and reliable rapid-assessment techniques for mapping marine biodiversity. One potential approach is to use ‘surrogates’ that function as proxies for the distribution of other, less easily sampled, ‘cryptic’ biota. Two potential surrogates for predicting arthropod faunal biodiversity on rock subtidal reefs were investigated in this study: (1) macroalgae, and (2) faunal subsets derived by aggregating the arthropod fauna at higher taxonomic levels. Faunal and macroalgal assemblage composition was only weakly correlated across sites reflecting broad faunal responses to changes in algal structural complexity and/or common environmental gradients. This suggests that algal species composition may not be very informative in mapping patterns of faunal species distribution on reefs. Instead, the best surrogates were related (i.e. nested), subsets of the faunal assemblages such as family-level taxon richness which was found to be a good predictor of arthropod species richness at independent test sites.     

Thermal modulation of pyruvate metabolism in the freshwater prawn Macrobrachium malcolmsonii: the role of lactate dehydrogenase

Temperature-induced alterations in the activity of the enzyme lactate dehydrogenase (LDH) were evaluated in the freshwater prawn Macrobrachium malcolmsonii in three groups of juveniles: controls maintained at 27±2 °C; test prawns exposed to 35 °C; test prawns exposed to 15 °C. Changes in LDH activity and lactate levels in key tissues were assessed after 48 hrs. LDH in the skeletal muscle of the prawns was also subjected to kinetic analysis at different temperatures. Native polyacrylamide gel electrophoresis (PAGE) analysis and colorimetric estimation revealed decreased LDH activity (compared to controls) in the gill, heart and haemolymph, but not in the skeletal muscle or hepatopancreas, of test prawns exposed to 15 °C; however, lactate levels were significantly lower in all the tissues of these test prawns. Conversely, prawns exposed to 35 °C revealed elevated LDH activity in all the tissues, barring the skeletal muscle, while lactate levels were significantly higher (compared to controls) in all the tissues of these prawns. Kinetic analysis of LDH in the skeletal muscle at different assay temperatures revealed temperature-dependent kinetic properties. The differences observed in LDH activity and levels of lactate in various tissues of prawns exposed to low and high temperatures suggest aerobic and anaerobic patterns of pyruvate metabolism at respective temperatures. The results obtained by kinetic analysis of LDH in the skeletal muscle suggest the occurrence of an adaptative response involving this enzyme that enables M. malcolmsonii to cope with effects of thermal stress. This revised version was published online in July 2006 with corrections to the Cover Date.     

Are different biodiversity metrics related to the same factors? A case study from Mediterranean wetlands

Conservation biology is mainly interested in prioritizing sites on the basis of their high biodiversity. Although species richness is a commonly used criterion, it does not take other crucial aspects of identifying conservation priority sites into account, such as rarity or taxonomic distinctness. Additionally, management efforts are usually focused on the conservation of a small number of species, mainly vertebrates. However, the biodiversity patterns of these faunal groups and the main factors which determine them cannot be generalized to other faunal groups (e.g. aquatic invertebrates). Therefore, the objectives of the present study are: (1) to compare the response of 11 biodiversity metrics in order to know which ones are redundant, (2) to identify key environmental factors for biodiversity, and (3) to find out whether sites with high biodiversity values also have a good habitat condition and high protection status. The study was done at assemblage level (crustaceans and insects) in 91 wetlands in the NE Iberian Peninsula. Regression tree models were used to identify the key factors influencing biodiversity, including water, wetland and landscape characteristics as explanatory variables. Generalized Linear models were used to establish the relationship between biodiversity metrics and protection status and habitat condition. The results obtained by the two sampled seasons were compared. Conductivity was the main factor influencing biodiversity metrics. Positive significant relationships were found between some biodiversity metrics and wetland habitat condition, whereas there were none for protection status, indicating the inadequacy of conservation policies to protect wetland aquatic invertebrate biodiversity.     

渤海夏季甲壳类群落结构的年际变化

基于2009~2010年及2012~2015年夏季(8月)进行的底拖网调查资料,研究了渤海甲壳类群落结构的年际变化。结果显示:(1)调查共捕获甲壳类33种,隶属于2目21科29属,其中虾类16种,蟹类16种,虾蛄1种;(2)甲壳类生态优势种类组成随年份变化,口虾蛄在每个年份均为绝对优势种;(3)2009~2013年,渤海甲壳类的物种数目、生物量和个体数密度均持续下降,2014~2015年逐步恢复;(4)聚类分析(CLUSTER)和多维标度分析(MDS)将6个调查年分为4个群组,单因子相似性分析(ANOSIM)表明群组间的群落结构呈显著性差异(P0.05),相似性百分比分析(SIMPER)表明口虾蛄、葛氏长臂虾和海蜇虾对群组区分的贡献率最高;(5)群落更替指数和迁移指数显示,渤海甲壳类群落的稳定性以2010年最好、2013年最差。总体来看,2011年蓬莱19-3平台溢油后的第3~4年,即2014~2015年渤海的甲壳类群落已逐渐恢复。     

Calcium concentration in leaf litter alters the community composition of soil invertebrates in warm-temperate forests

Many studies have shown the effects of aboveground plant species on soil organisms due to differences in litter quality. However, the calcium concentration in soil has received less attention as a controlling factor of soil invertebrate communities, even though it is an essential element for many animals, especially crustaceans. Litter of Japanese cedar (Cryptomeria japonica) plantations, which account for 19% of the forested area in Japan, has a higher calcium concentration compared to other taxa such as broad-leaved trees. We predicted that C. japonica plantations affect soil invertebrates by altering calcium availability. We compared soil properties including exchangeable calcium concentration and soil invertebrate communities between C. japonica plantations and natural broad-leaved forests. Exchangeable calcium was significantly higher in soil from cedar plantations than in that from broad-leaved forests. The invertebrate community composition differed between the two forest types and was best explained by the exchangeable calcium concentration. In particular, two major taxa of soil crustaceans (Talitridae and Ligidium japonicum) were found only in cedar plantations. Our results suggest that calcium concentrations in soil are altered in C. japonica plantations and that this affects soil invertebrate communities.     

The 70-kDa Heat-shock Protein as a Potential Biomarker of Quality of the Parapenaeus longirostris Shrimp Flesh

The deep-water rose shrimp, Parapenaeus longirostris, is a target species of the Mediterranean fisheries mostly caught by trawlers offshore, processed, and frozen on board. The effects of thawing on shrimp muscle exudate collected at 0, 1, 2, 3 days after thawing were investigated. In total, 70-kDa heat-shock protein (Hsp70), alpha (α)-enolase, and manganese superoxide dismutase (Mn-SOD) were selected as metabolic and stress-related proteins and analyzed by immunoblotting on exudates. Data were compared for the amount of exudates collected and the pH values. Among the investigated proteins, only the Hsp70 levels showed a decrease related to the post-thawing period and correlated with both the significant increase of the exudate amount and the pH values. These data strongly suggest the potential use of Hsp70 as an early predictive biomarker for quality of the P. longirostris shrimp after thawing.