The biology and ecology of the invasive silver-cheeked toadfish (Lagocephalus sceleratus), with emphasis on the Eastern Mediterranean

Invasive species pose threats to either human health or inflict ecological and/or economic damage. The silver-cheeked toadfish (Lagocephalus sceleratus), a Lessepsian species, is one of the most harmful species in the Mediterranean Sea, because of its potent neurotoxin, impacts on marine biodiversity, and the increased costs and labor they inflict on fishers. Since the catch and consumption of this pufferfish is prohibited by almost all countries bordering the Mediterranean, they have now expanded into the entire Mediterranean and Black Sea. We performed a comprehensive study of L. sceleratus covering ecological aspects, growth, reproduction, diet and trophic level based on samples from southwestern coasts of Turkey. The estimated growth parameters were L∞ = 88.7 cm, K = 0.27 year-1, C = 0.6 and WP = 0.1. Their sex-ratio was M/F = 1:0.69. Lagocephalus sceleratus appears to be a batch spawner with discontinuous oocyte recruitment and has different spawning seasons in the Eastern Mediterranean which seem to be based on temperature cues which get shorter in duration as one moves north from the Suez. We also report their first positive ecological trait, that they are controlling some other invasive species through their diets, such as lionfish, Red Sea goatfish, rabbitfish and longspine sea urchins, in addition to controlling themselves through cannibalism, which appears to be density-dependent. They are indeed a top predator in the region with a trophic level of 4.1. We suggest that targeted fishing using improved gear-types to reduce fishing gear damages are initiated, and that finding commercial markets for pufferfish could help to naturally fund ongoing control efforts.

Advances in Egyptian Mediterranean Coast Climate Change Monitoring

This paper characterizes non-indigenous fish species (NIS) and analyses both atmospheric and sea surface temperatures for the Mediterranean coast of Egypt from 1991 to 2020, in relation to previous reports in the same areas. Taxonomical characterization depicts 47 NIS from the Suez Canal (Lessepsian/alien) and 5 from the Atlantic provenance. GenBank accession number of the NIS mitochondrial gene, cytochrome oxidase 1, reproductive and commercial biodata, and a schematic Inkscape drawing for the most harmful Lessepsian species were reported. For sea surface temperatures (SST), an increase of 1.2 °C to 1.6 °C was observed using GIS software. The lack of linear correlation between annual air temperature and annual SST at the same detection points (Pearson r) could suggest a difference in submarine currents, whereas the Pettitt homogeneity test highlights a temperature breakpoint in 2005–2006 that may have favoured the settlement of non-indigenous fauna in the coastal sites of Damiette, El Arish, El Hammam, Alexandria, El Alamain, and Mersa Matruh, while there seems to be a breakpoint present in 2001 for El Sallum. This assessment of climate trends is in good agreement with the previous sightings of non-native fish species. New insights into the assessment of Egyptian coastal climate change are discussed.

First record of the Lessepsian fish Parexocoetus mento in Italian waters and GIS-based spatial and temporal distribution in Mediterranean Sea

The Strait of Sicily in the middle of the Mediterranean Sea is considered a crossroads between the western and the eastern basins for species immigrating from the Atlantic Ocean and Lessepsian species. Among the latter, the African sailfin flyingfish Parexocoetus mento was recently collected from Lampedusa Island in November 2017, and represents the first documented record in Italian waters. In this paper, the morphological and meristic characteristics of this specimen are reported and discussed, compared with the other species of the genus Parexocoetus. Furthermore, as mapping and monitoring the distribution of invasive species is crucial to understanding their establishment and spread and then to manage the invasion process, the occurrences distribution of P. mento in the Mediterranean Sea was studied. The application of GIS-based spatial statistics allowed to identify significant clustering areas and dispersion areas of the species, summarizing the key characteristics, and underlining directional trends of distribution. GIS analysis identified two similar groups of records (1935/1966 and 1986/2017 time period), showing a change of distribution spatial pattern over time. An earlier spread direction in the Mediterranean east coast and a settled area of P. mento were found. The analysis also includes the specimen caught in Italian waters.

Population Dynamics of Suez Pufferfish (Lagocephalus suezensis) in Iskenderun Bay

Suez pufferfish (Lagocephalus suezensis) is a Lessepsian species introduced to the Mediterranean via the Suez Canal. This study was carried out for the identification of some population dynamics parameters of Suez pufferfish (Lagocephalus suezensis) distributed along the western coast of Iskenderun Bay. Samples were seasonally collected from two transects at 10 and 20 m depth contours from 2006 to 2017 using a commercial bottom trawl net with 44 mm mesh size. A total of 1279 individuals were investigated. Among them 427 were males, 586 were females, 266 were juveniles. Total length ranged from 5.2 to 24.0 cm and mean length was 13.44 ± 2.02 (± standard error) cm; total weight ranged from 1.77 to 232.97 g and mean weight was 32.05 ± 14.28 g for all individuals. Length-weight relationships were W=0.02*TL2.83 for males, W= 0.02*TL2.82 for females, and W=0.02*TL2.89 for aggregated data. The von Bertalanffy growth parameters were as follows; L∞ = 24.97 cm, K = 0.60 year-1, t0= -0.28, Rn = 0.145 for all specimens. Growth performance index was calculated as 5.92. Rates of total (Z) and natural (M) mortality was found to be 1.07 and 0.981 year-1.

Crustacea Decapoda from the Rhodes Island Area (Eastern Mediterranean): New Records and an Updated Checklist

Decapod crustaceans are ecologically and commercially important members of marine communities. Faunal surveys constitute essential tools for the understanding of local diversity, especially in areas subjected to significant alterations of community composition due to climate changes, anthropogenic impacts, and biological invasions. Following a literature review and the study of new samples, we hereby update on the Crustacea Decapoda from the Rhodes Island area (Greece), situated in a key position in the eastern Mediterranean Sea. Published data yielded records of 120 species, whereas 28 taxa are recorded here for the first time from the study area. Among them, the collection of Liocarcinus bolivari widens its distribution to the eastern Mediterranean. Details on material examined and distributional/faunal remarks are provided for the species newly recorded and for some other native and alien species rarely reported from Rhodes. The present paper raises the local decapod biodiversity to 148 species, accounting for ~50% of the Hellenic Aegean decapod fauna and provides a useful baseline for analysing the long-term changes in the local fauna and the westward spreading of Lessepsian species. Despite present advances, the lack of records of many common Mediterranean species may be still due to limited fieldwork in some habitats rather than a true absence.

Biological aspects of two coexisting native and non-native fish species in the Aegean Sea: Pagellus erythrinus vs. Nemipterus randalli

Nowadays, the Mediterranean is a hotspot of biodiversity, characterized by changes in fish communities due to invasions. These invasions, mainly occurring through the entrance of species through the Suez Canal, a process called Lessepsian migration, has been increasing in the last 40 years. It is reported that, in Turkish seas, where 512 fish species are found, are 75 Lessepsian species. However, knowledge about the impact of Lessepsian species on native species is insufficient. This study aims to determine the bio-ecological characteristics and food interactions of a native Pagellus erythrinus and non-native Nemipterus randalli distributed in the Gökova Bay.In the monthly sampling survey, carried out between January 2016 and December 2016, 1698 N. randalli and 945 P. erythrinus individuals were collected. Length, weight, age, sex distributions and ratios, length-age, weight-age, length-weight relationships, condition factors, stomach contents and reproduction periods were examined to determine the interaction between species. According to results, the life span of P. erythrinus is longer than N. randalli in the Gökova Bay. Nevertheless, N. randalli grows faster than P. erythrinus. Reproduction periods of both two species show similarities. Food competition between species is found to be significantly high. Results of condition factors exhibit that N. randalli shows an increased ability to exploit the available food sources. Pagellus erythrinus displays strategies such as: early maturation, short reproduction period, reproduction in the deeper waters and batch spawning, to compete with N. randalli. With the invasive characteristics of N. randalli established a successful population in the Gökova Bay.

Lessepsian invaders reshape soft substrate assemblages on the Israeli Mediterranean shelf

The ‘Lessepsian invasion’ – the massive influx of Indo-Pacific biota into the Mediterranean Sea via the Suez Canal – is the largest marine biological invasion. The lack of data on pre-invasion community composition, however, severely impairs our understanding to which degree the taxonomic and functional composition of shallow-water assemblages has been modified by the invasion. Shelly death assemblages (DAs) encountered in surficial sediments represent a unique archive of past community states that enable overcoming this impediment. This is because they change more slowly (10-10,000 years) than the corresponding living assemblages (LAs; yearly scales of turnover). Strong and rapid directional changes such as those due to human activities are therefore not immediately captured by DAs, leading to a greater live-dead (LD) mismatch than under natural processes alone. We compared molluscan LAs and DAs collected along a depth transect down to 40 m on the Mediterranean shelf of Israel. High dissimilarity in taxonomic composition (Jaccard-Chao index), rank-order agreement of species relative abundances (Spearman’s rho), and differences in trophic guild composition suggest a major ecosystem shift in recent times. Our findings reveal that Lessepsian species have not only replaced native taxa, but also altered the functional properties of local molluscan assemblages.

Lessepsian invaders reshape soft substrate assemblages on the Israeli Mediterranean shelf

The ‘Lessepsian invasion’ – the massive influx of Indo-Pacific biota into the Mediterranean Sea via the Suez Canal – is the largest marine biological invasion. The lack of data on pre-invasion community composition, however, severely impairs our understanding to which degree the taxonomic and functional composition of shallow-water assemblages has been modified by the invasion. Shelly death assemblages (DAs) encountered in surficial sediments represent a unique archive of past community states that enable overcoming this impediment. This is because they change more slowly (10-10,000 years) than the corresponding living assemblages (LAs; yearly scales of turnover). Strong and rapid directional changes such as those due to human activities are therefore not immediately captured by DAs, leading to a greater live-dead (LD) mismatch than under natural processes alone. We compared molluscan LAs and DAs collected along a depth transect down to 40 m on the Mediterranean shelf of Israel. High dissimilarity in taxonomic composition (Jaccard-Chao index), rank-order agreement of species relative abundances (Spearman’s rho), and differences in trophic guild composition suggest a major ecosystem shift in recent times. Our findings reveal that Lessepsian species have not only replaced native taxa, but also altered the functional properties of local molluscan assemblages.