Ocean warming is the key filter for successful colonization of the migrant octocoral Melithaea erythraea (Ehrenberg, 1834) in the Eastern Mediterranean Sea

Climate, which sets broad limits for migrating species, is considered a key filter to species migration between contrasting marine environments. The Southeast Mediterranean Sea (SEMS) is one of the regions where ocean temperatures are rising the fastest under recent climate change. Also, it is the most vulnerable marine region to species introductions. Here, we explore the factors which enabled the colonization of the endemic Red Sea octocoral Melithaea erythraea (Ehrenberg, 1834) along the SEMS coast, using sclerite oxygen and carbon stable isotope composition (δ18OSC and δ13CSC), morphology, and crystallography. The unique conditions presented by the SEMS include a greater temperature range (∼15 °C) and ultra-oligotrophy, and these are reflected by the lower δ13CSCvalues. This is indicative of a larger metabolic carbon intake during calcification, as well as an increase in crystal size, a decrease of octocoral wart density and thickness of the migrating octocoral sclerites compared to the Red Sea samples. This suggests increased stress conditions, affecting sclerite deposition of the SEMS migrating octocoral. The δ18Osc range of the migrating M. erythraea indicates a preference for warm water sclerite deposition, similar to the native depositional temperature range of 21–28 °C. These findings are associated with the observed increase of minimum temperatures in winter for this region, at a rate of 0.35 ± 0.27 °C decade−1 over the last 30 years, and thus the region is becoming more hospitable to the Indo-Pacific M. erythraea. This study shows a clear case study of “tropicalization” of the Mediterranean Sea due to recent warming.

Ecosystem service preferences across multilevel stakeholders in co-managed forests: Case of Aberdare protected forest ecosystem in Kenya

A better understanding of Ecosystem Services (ES) contributes to sustainable use while conserving the ecosystems mainly in resource-rich developing regions. This paper explores multilevel stakeholder perceptions on the most important ES provided by Aberdare Forest Ecosystem (AFE). The importance rank matrix model was employed to establish the ES preferences of 15 selected key organisations involved in AFE co-management. A two-way ANOVA inferential analysis was used to compare the differences in ES type importance. The results revealed statistically significant differences between provisioning, regulating and cultural ES. Regulating ES were identified as the most important compared to provisioning and cultural ES; a gradual stakeholder preference shift from forest tangible goods. Water, wildlife habitat, flood regulation, carbon intake and climate regulation were identified as the most important ES by all the stakeholders. Therefore, it is important to understand the gradual changes in ES preferences by various stakeholders involved in the co-management of natural resources. This knowledge could be important to the decision-makers in sustainable co-management planning for natural resources and to enhance sustainable utiliation of ES.

Using Stable Carbon and Nitrogen Isotopes to Evaluate Parrotfish Diet

With limited inconclusive data provided by gut content analysis, stable isotope analysis has recently emerged to validate trophic position and dietary intake. In this study, a dual isotope approach was used to reveal parrotfish feeding. Comparisons of δ13C and δ15N values of muscle and liver among yellow barred (Scarus dimidiatus), rosy cheek (S. psittacus), and blue-barred (S. ghobban) parrotfishes from Canigao Island, Matalom, Leyte were made to track dietary shifting and to compare dietary carbon intake. Trophic assignment was based on the assumption that consumers are enriched by a factor of 3-4‰ for δ15N, relative to their diet. The δ13C values of muscle tissues of the three species of parrotfish were significantly higher (p=0.001) than those of their liver suggesting dietary shifting. The δ13C values of both muscle and liver tissues of S. dimidiatus were significantly (p<0.001) higher than those of S. psittacus and S. ghobban, but δ13C values of muscle and liver of S. psittacus and S. ghobban did not vary significantly. These mean that S. dimidiatus have different long term and recent dietary carbon intake compared to the other two species, while S. psittacus and S. ghobban have relatively the same dietary carbon intake. Considering the 1‰ δ13C trophic enrichment of consumers relative to their diet, possible dietary carbon sources of the sampled parrotfish include Dendronephthya spp., Ulva reticulata, Sargassum oligocystum, Dictyota sp., Digenea sp., Chlorodesmis sp., and Sargassum muticum suggesting that parrotfishes are generalist consumers. Mean stable isotope nitrogen ratios of S. dimidiatus (5.9‰), S. psittacus (6.9‰) and S. ghobban (6.7‰) together with their carbon isotope ratios confirmed that all sampled parrotfish species are generalist primary consumers.

Factors Influencing 14C Ages of the Pacific Rat Rattus Exulans

An isotopic database for the Pacific/Polynesian rat (Rattus exulans) and foods that it scavenges is used to examine diet-induced 14C age variation in omnivores. We discuss a suite of 26 δ14C determinations and 13C and 15N analysis for modern Pacific/Polynesian rat bone gelatin and available food items from Kapiti Island, New Zealand (40°51'S, 174°75'E). These analyses provide the first isotopic data for modern specimens of the species, collected as part of a larger project to determine potential sources of bias in unexpectedly old 14C age measurements on subfossil specimens of R. exulans from New Zealand. Stable C, N and 14C isotopic and trapping data are used to trace carbon intake via the diet of the rats in each habitat. Data from specimens linked to five specific habitats on the island indicate that modern populations of R. exulans are not in equilibrium with atmospheric values of δ14C, being either enriched or depleted relative to the atmospheric curve in 1996/97, the period of collection. The δ14C values recorded for R. exulans are associated with diet, and result from variation in δ14C values found in animal-protein food items available to a scavenging omnivore. The titer of carbon deviating from atmospheric values is believed to be derived from the essential amino acids in the protein-rich foods of the rat diet.Present evidence suggests that the depletion required to affect 14C ages limits the possibility that diet introduces dramatic offsets from true ages. Marine diets, for example, would have a variable effect on ages for terrestrial omnivores, contraindicating the application of a standard marine correction for such specimens. We suggest that to identify the extent to which diet may influence the 14C age in a given specimen of terrestrial omnivore, the separation and dating of essential amino acids vs. a nonessential amino, such as glycine, be applied.

Age-related differential catabolism in the snail, Viviparus georgianus, and its significance in the bioenergetics of sexual dimorphism

Catabolic partitioning of carbon and nitrogen was investigated to clarify the sexual dimorphism of bioenergetics in Viviparus georgianus. Experiments involved summer stocks of 3-, 15-, 27-, and 39-month-old male and female snails grazing on an artificial high protein diet and, for 15-month snails only, comparison tests using a lower protein diet. Per snail ingestion and partitioning rates and growth are generally maximal for 15-month snails and decline with age in both sexes. In each age group, females have lower rates for weight-specific ingestion of protein carbon and nonprotein carbon than males. For protein carbon, females also show lower rates of catabolism. Compensation for the lower protein diet is more marked in females, which increase total carbon intake by 58% and reduce catabolic use of protein carbon by 40% (against a male reduction of 25%). When discussing evolutionary problems in terms of actuarial bioenergetics, quantification of both physiological rates and ecological efficiencies can be of value in a broadly adaptational approach.