Population ecology of the intertidal xanthid crab Leptodius exaratus (H. Milne Edwards, 1834) (Decapoda: Brachyura: Xanthidae) on rocky shores in Kuwait, Arabian (Persian) Gulf

Al-Wazzan, Z., Gimenez, L., Behbehani, M. and Le Vay, L. (2024)

Leptodius exaratus (H. Milne Edwards, 1834) is an exploited species that has been used as bait for recreational fishing in Kuwait. The biological and ecological aspects of the species required to manage this practice are limited. We investigated the life history and population ecology of L. exaratus in the northwestern Arabian (Persian) Gulf. The spawning season of the crab in Kuwait starts in the late spring and continues through the summer and ends in September. Fecundity is highly correlated to female body size and ranges 2,533–11,991 eggs clutch–1, with a mean number of 7,055 eggs clutch–1. Juveniles are generally recruited between July and September, with lower minor recruitment levels occurring in October and November. Growth is highly seasonal, being slow during the cold season (October-February) and high during the warmer season (March and September), with a higher growth rate in males than in females. The seasonality of growth and reproduction of L. exaratus in the region is strongly related to ambient air and water temperatures. Sexual dimorphism is highly significant between males and females with males, reaching reproductive maturity at 17.43 ± 0.53 mm carapace width (CW) and females at 9.58 ± 1.21 mm CW. The overall sex ratio for the species is 0.8:1 (males:females). Furthermore, the life span of 3–4 yr and an overall mortality slightly higher in males than in females. The results of our study could be used to determine fishery management strategies such as minimum catch sizes and closures periods. The results on life history and dynamics of the complex life cycle of L. exaratus contribute to conservation and sustainable exploitation of the species in Kuwait.

Development and application of a second-generation multilingual tool for invasion risk screening of non-native terrestrial plants

Vilizzi, L., Piria, M., Pietraszewski, D., Giannetto, D., Flory, L., Herczeg, G., H., Sermenli, G.B., Britvec, M., Jukoniene, I., Petrulaitis, L., Kosić, I.V., Almeida, D., Al-Wazzan, Z., Bakiu, R., …and Yazlık, A. (2024)

Under the increasing threat to native ecosystems posed by non-native species invasions, there is an urgent need for decision support tools that can more effectively identify non-native species likely to become invasive. As part of the screening (first step) component in non-native species risk analysis, decision support tools have been developed for aquatic and terrestrial organisms. Amongst these tools is the Weed Risk Assessment (WRA) for screening non-native plants. The WRA has provided the foundations for developing the first-generation WRA-type Invasiveness Screening Kit (ISK) tools applicable to a range of aquatic species, and more recently for the second-generation ISK tools applicable to all aquatic organisms (including plants) and terrestrial animals. Given the most extensive usage of the latter toolkits, this study describes the development and application of the Terrestrial Plant Species Invasiveness Screening Kit (TPS-ISK). As a second-generation ISK tool, the TPS-ISK is a multilingual turnkey application that provides several advantages relative to the WRA: (i) compliance with the minimum standards against which a protocol should be evaluated for invasion process and management approaches; (ii) enhanced questionnaire comprehensiveness including a climate change component; (iii) provision of a level of confidence; (iv) error-free computation of risk scores; (v) multilingual support; (vi) possibility for across-study comparisons of screening outcomes; (vii) a powerful graphical user interface; (viii) seamless software deployment and accessibility with improved data exchange. The TPS-ISK successfully risk-ranked five representative sample species for the main taxonomic groups supported by the tool and ten angiosperms previously screened with the WRA for Turkey. The almost 20-year continuous development and evolution of the ISK tools, as opposed to the WRA, closely meet the increasing demand by scientists and decision-makers for a reliable, comprehensive, updatable and easily deployable decision support tool. For terrestrial plant screening, these requirements are therefore met by the newly developed TPS-ISK.

Temporal and spatial infection patterns of the rhizocephalan parasite Parasacculina leptodiae (Guérin-Ganivet, 1911) in the crab Leptodius exaratus along the shores of Kuwait

Al-Wazzan, Z., Waser, A.M., Glenner, H., Giménez, L. and Thieltges, D.W. (2021)

Rhizocephalan cirripedes are a very unique group of parasites infecting decapod crustaceans, but apart from a few well-studied species, little is known on their ecology and impact on hosts. Here we report on the results of a 14-month study of infestations of the rhizocephalan Parasacculina leptodiae in the rocky shore crab Leptodius exaratus along the shores of Kuwait in the Persian (Arabian) Gulf. Monthly samples along an intertidal gradient revealed a slightly higher prevalence of P. leptodiae in female (18%) compared to male crabs (11%) and marked differences in prevalence among the sampling sites. Crabs from more sheltered locations in Kuwait Bay showed lower prevalence of P. leptodiae compared to crabs from more exposed sites. Seasonal patterns were largely absent, but prevalence in female crabs showed some monthly variation depending on the site. Rhizocephalan prevalence was generally highest in both crab sexes at the lower shores. This possibly resulted from lower exposure of crabs to infective stages in the higher intertidal and movements of infected crabs to lower parts of the shore. Prevalence of ovigerous females significantly declined with increasing local parasite prevalence. This suggests that the well-known castrating effects of rhizocephalans on individual hosts can also affect local crab reproduction at the population level which has not been shown before. Our results indicate that the rhizocephalan P. leptodiae is a common parasite of the rocky shore crab L. exaratus along the shores of Kuwait, with potential effects on the crab’s population dynamics which warrants further study.