Coral reef and atoll lagoons are among the most diversified marine ecosystems but also the most affected by the combined effects of climate change and human activities. The Iles Eparses (Scattered Islands) in the Western Indian Ocean have been little affected by human pressure and can be considered to be "pristine" ecosystems. Metazooplankton plays a major role in the functioning and productivity of aquatic ecosystems, and this study was undertaken: (i) to determine the spatial abundance, distribution and species composition of metazooplankton, (ii) to assess the effect of metazooplankton grazing on pico- and nanophytoplankton and (iii) to analyze the trophic positions of metazooplankton by using the stable isotope signatures of a wide variety of taxa and particulate organic matter from the Iles Eparses and Mayotte. Tromelin Island (which is not located in the Mozambique Channel) had the lowest metazooplankton abundance with no cyanobacteria Trichodesmium spp. or mollusks (pteropods) presence, and with δ(15)N signatures of organisms that were higher than for the islands in the Mozambique Channel. Trichodesmium spp. was found in the Mozambique Channel and the plankton food web was probably based preferentially on these cyanobacteria with lower δ(15)N signatures indicating direct or indirect trophic transfer of diazotrophic nitrogen to metazooplankton. Three of the islands were distinct: Europa had the highest proportion of copepods, with oithonids being dominant, which is typical of rich mangrove systems, while Juan de Nova and Mayotte seemed to be the sites most affected by human activity with a high abundance of appendicularians and distinct particulate organic matter ∂(13)C signatures. Grazing experiments showed that food could be a limiting factor for metazooplankton in the Iles Eparses. However, the effect of metazooplankton grazing on phytoplankton appeared to be very low (0.01-2.32% of the total phytoplankton per day).

Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) is an invasive and extremely damaging leaf-mining moth of South American origin. It is a serious pest of tomatoes. This species was first recorded outside of its native range in Spain (2006), and has subsequently spread into Asia and Africa. Here we report the first records of this species for the Republic of South Africa, where moths were first trapped in August and October 2016. The species was identified using both morphological and molecular approaches. Monitoring of the spread of tomato leaf miner in South Africa and the implementation of control measures are managed by the Department of Agriculture, Fisheries and Forestry (DAFF), South Africa.

The freshwater jellyfish Craspedacusta sowerbii is one of the most widespread invasive species, but its global distribution remains uncertain due to ephemeral appearances and general lack of information in various aquatic environments. The aim of this study was to map current and future distributions (2050 and 2100) using Species Distribution Models allowing to visualize the habitat suitability and make projections of its changes under potential climate change scenarios. Except in Oceania where the range decreased, an expansion of C. sowerbii was projected during the next century under modeled future scenarios being most intensive during the first half of the century. The present study shows that the expansion of C. sowerbii worldwide would be facilitated mainly by precipitation, vapor pressure, and temperature. The predictions showed that this species over the eighty years will invade high-latitude regions in both hemispheres with ecological consequences in already threatened freshwater ecosystems.

No abstract

The invasive freshwater jellyfish Craspedacusta sowerbii, native from East Asia (Yangzi Jiang River), was introduced in Europe for the first time in the basins of the Royal Botanic Garden in London. From the beginning of the 20th century, worldwide reports of the presence of C. sowerbii have been increasing (USA, Canada, Europe, Australia, Russia). Despite its now worldwide distribution, C. sowerbii has rarely been the subject of recent studies. Moreover, C. sowerbii is difficult to rear in the laboratory, and individuals generally from the wild have only been reared for short periods. Many aspects of laboratory cultures have proven to be problematic for all stages of the life cycle (from frustule to medusae): lack of optimal growing system (circular current or not), water quality (physical and chemical conditions), diet (the type of food), and temperature. In this article, we present a technique for culturing all life stages of C. sowerbii, from polyps to medusae, to study its life history in the laboratory. To demonstrate the success of our culture protocol, the growth of polyps was measured for 80 days at 19 and 29°C. Colony growth increased at both temperatures in our culture system, and data were similar to those presented in the literature, illustrating the success of this protocol. Medusae were cultured for 70 days, and their bell diameter increased from 0.60 ± 0.08 mm (Day 0) to 9.0 ± 2.1 mm (Day 32). We developed a closed culture system that allowed specimens (i.e., polyps and medusae) to be maintained for more than 2 months (80 days for polyps, 72 days for medusae). This culture system will allow researchers in the future to study more precisely the metabolism (growth, ingestion, longevity) of polyps and medusae to understand life‐history characteristics important to this species' ecology (periods of medusae production, predation, and diet).

One of the consequences of climate change and globalization is the recent proliferation of the invasive blue crab Callinectes sapidus in the Mediterranean Sea. In this study, C. sapidus thermal tolerance was investigated through experiments based on species metabolic response (measuring respiration rates) to a wide temperature range. Based on metabolic rates, Thermal Habitat Suitability (THS) maps were performed on current and futures temperature conditions in the Mediterranean Sea. Thermal Performance Curve showed a CTmax at 40°C and an optimum at 24°C. Respiration rate increased between 12°C and 24°C and decreased until 30°C. At the highest temperatures (> to 30°C) a pointed increase in the respiration rate values was observed from 32°C before the organisms’ death at 40°C. Predictive maps showed that the whole basin shows suitable conditions for population maintenances of C. sapidus in all used warming scenarios. The future scenarios show a mean increase of +0.2 of the THS over the year. The present study increases the understanding of the ecological performance and potential distribution of C. sapidus. This information will contribute to the design and implementation of risk assessment and management plans of this impactful crustacean in the Mediterranean Sea.

This is an open access article under the terms of the Creative Commons Attribution Licence (CC BY 4.0), which permits use, distribution and reproduction in any medium provided the original work is properly cited.

The invasive freshwater hydromedusa Craspedacusta sowerbii Lankester, 1880 (phylum Cnidaria, class Hydrozoa, family Olindiidae) is native from East Asia but for more than 20 years, reports of this species have been increasing in Europe, North America, and Australia. Due to the sporadic presence of the medusa stage and difficulties in the sample polyp stage, there is a lack of data on the physiological parameters of C. sowerbii and its potential impact. We present data on growth and ingestion rates of the medusa stage measured at 29°C, temperature at which polyps are maintained in the Cinéaqua Aquarium (Paris). Medusa growth increased from 0.60 ± 0.08 to 9.0 ± 2.1 mm (mean: 0.28 ± 0.26 mm d−1), and gonads appeared after 11.5 ± 3.0 days. Ingestion rates increased significantly from 28 ± 16 prey ind−1 d−1 (<1 mm) to 442 ± 170 prey ind−1 d−1 (>7 mm).