Size distribution and sex ratio between populations of the artisanal harvested land crab Cardisoma guanhumi (Decapoda: Gecarcinidae), with the estimation of relative growth and size at sexual maturity in Puerto Rico

Introduction: Knowledge of growth patterns, sex ratio, and sexual maturity are of importance to exploited populations. The land crab Cardisoma guanhumi is an artisanal and subsistence exploited species in Puerto Rico. However, the growth patterns and sexual maturity of the local populations are not known. Objectives: This study has a double objective: (1) to compare the size and sex structure between populations and (2) to model the relative growth of structures related to reproduction to estimate the average size of morphometric sexual maturity (MSM) for both males and females. Methods: A total of 2 849 specimens were captured from nine dispersed populations on the island between 2001 and 2020. Carapace width (CW) was measured as an estimator of the absolute size of all individuals, together with the propodus length (PL) in males and the abdomen width in females (AW). Differences in length structure between sexes and populations were tested by applying goodness-of-fit tests based on Kernel Density Estimators (KDE). The relative growth pattern was modeled adjusting a spline from which the maximum of its second derivative was calculated as an estimator of the MSM, and bootstrapping was used to generate confidence intervals. Results: Differences were found in size structures, between sexes, and between sites. Our estimates of morphometric sexual maturity resulted in a sexual maturity size for males between 57.9 and 79.0 mm CW, while in females, morphological maturity occurs between 43.8 to 51.5 mm CW. Conclusions: We found inter-population differences in body size that can be attributed to differences in the history of changes of land use and the exploitation biased towards larger individuals, though differences in recruitment should also be considered. Current regulations in Puerto Rico protect female crabs but not to larger male crabs. The regulation establishes that crabs smaller than 64 mm carapace width cannot be captured, leaving immature male crabs over 64 mm CW unprotected. We suggest considering different size limits depending on the sex of the crab. This will allow the full range of sizes where sexual maturity is reached to be protected, increasing the likelihood of the population’s size to increase.

Conservation of the endangered blue land crab Cardisoma guanhumi Latreille in Latreille, Le Peletier, Serville & Guérin, 1828 (Decapoda: Brachyura: Gecarcinidae) in Brazil: optimal habitats and environmental factors

Cardisoma guanhumi Latreille in Latreille, Le Peletier, Serville & Guérin, 1828, the blue land crab, is a marine semi-terrestrial crab that builds burrows in different habitats along estuaries, an ecosystem severely modified and fundamental to this endangered species in Brazil. The presence of adequate habitats and physical, chemical, and biological conditions often determine the spatial distribution of populations. We aimed to characterize the most relevant environmental conditions among the main environments present in southern Bahia state, Brazil, and evaluate their influence on the spatial distributions of C. guanhumi to define which habitats are most critical for the conservation of the species. Our results showed that there is no relationship between spatial distributions and any particular habitat, but instead to the physical and other environmental parameters studied. Low-elevation areas along the river shore, shading, a supply of leaf litter, and bare sandy substrate are highlighted as priority for the conservation of C. guanhumi. These physical factors limit the distribution of juveniles, which form dense groups on river shores without significant differences between habitats. The preservation of the native forest and restinga shrubs that border rivers appear as fundamental for the conservation of the species.

QUANTIFICAÇÃO DOS TEORES DE METAIS TRAÇOS (Al, As, Ba, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb e Zn) NO Cardisoma guanhumi, DO ESTUÁRIO DE SERINHAÉM, APA DO PRATIGI, BAHIA

A fauna bentônica é uma bioindicadora de estresse ambiental em ecossistemas estuarinos, já que possui o ciclo de vida associado ao sedimento, exercendo suas funções metabólicas, além de sofrer possíveis alterações em decorrência da retenção e variação de concentração de determinadas substâncias (AUGUSTO, 2010).

Genetic diversity of the blue land crab Cardisoma guanhumi (Latreille 1825) in the Alvarado Lagoon System in Veracruz, gulf coast of Mexico

In the Alvarado Lagoon System (ALS) in south-central Veracruz on Mexico's gulf coast, the blue land crab, Cardisoma guanhumi, a semi-terrestrial crustacean species, represents an important fishery resource, but one that is subject to overexploitation and habitat destruction. Identifying genetic diversity and the genetic unit are required to establish efficient conservation strategies. The present study's goal was to assess the genetic structure and degree of genetic diversity of C. guanhumi populations along the ALS. A fragment of the D-loop region of the mtDNA (750 bp) and a partial sequence of the COI gene (580 pb) was sequenced for 120 specimens collected at four sites in the ALS. Genetic diversity indices were estimated for each marker. The study sites' gene flow was estimated, as was the effective population size and the mutational rate for each locality. A haplotype network was built to estimate the gene genealogies of the populations. A Tajima's neutrality test, Fu tests, and mismatch analysis were performed to detect demographic expansion. Results show that this C. guanhumi population has high genetic diversity with a large gene flow among the localities studied and expanded during the recent evolutionary past. All haplotypes from both markers are novel for the species, according to the NCBI GenBank. The high genetic diversity and genetic connectivity among sites suggests that the size of blue crab populations in the ALS has not been drastically affected by past exploitation. Finally, management strategies are proposed to protect the species.

MORPHOMETRY OF BLUE LAND CRAB (CARDISOMA GUANHUMI) BURROWS: ICHNOLOGICAL CONTEXT AND PALEOENVIRONMENTAL IMPLICATIONS

ABSTRACT A large brachyuran, the blue land crab (Cardisoma guanhumiLatreille, 1825) is a keystone species and a prolific burrower in a variety of low-latitude supratidal habitats; however, few studies have addressed its ichnological aspects. Here we present a detailed morphological assessment of C. guanhumi burrows and make comparisons to Macanopsis plataniformis, a trace fossil thought to be constructed by a similar brachyuran. Using nine burrow casts from a mangrove wetland on San Salvador Island, Bahamas, 29 dimensionless morphometric parameters were compared. Results of Bray-Curtis tests show high overall similarity index (0.85) between casts, with complexity, tortuosity, and opening inclination angle having moderate to high similarity (> 0.8). End chamber angle of the blue land crab has highest similarity both within the modern morphometric parameter dataset (> 0.9) and to that of M. plataniformis (0.88). The large terminal chamber is particularly important because of its high preservation potential, as a repository for organic remains, and as a reliable water table (∼ sea-level) indicator. Cluster analysis suggests size-independent Macanopsis-resembling burrow morphology among different extant taxa can be discriminated via quantitative neoichnological methods. Our findings demonstrate how a quantitative assessment of modern burrows and their likely counterparts from the sedimentary record can help constrain tracemaker identity and aid paleoenvironmental reconstruction of low-energy microtidal settings.

Effect of Cardisoma guanhumi (Land Crab) Extract on Haematology and Lungs Histology in Swiss Mice Infected with Bordetella pertussis

Pertussis is an acute human respiratory tract disease caused by Bordetella pertussis, a known international pathogen that affects infants, children and adults. This study is aimed at investigating the changes in haematological parameters and histopathological changes of the lungs connected with Bordetella pertussis infection in swiss mice and to evaluate the potential of Cardisoma guanhumi extract to reverse these adverse changes about erythromycin treatment. The animals were divided into five groups: Group 1 was normal to control, group 2 was infected with Bordetella pertussis without treatment (negative control), group 3 and 4 were Bordetella pertussis infected and treated with 300 mg/kg and 600 mg/kg of the extract respectively and group 5 were infected and treated with 4000 mg/70 kg of erythromycin in divided doses. The animals were inoculated with a single infectious dose of Bordetella pertussis bacteria and were consequently treated with the graded doses of the extract and erythromycin for eighteen days after the animals were confirmed infected. The mice were humanely sacrificed using diethyl ether anaesthesia and blood samples were taken for liver function investigation and liver tissue harvested and processed for histological examination. The result showed that Cardisoma guanhumi extract reversed the changes in the haematological parameters and pathological changes in the lungs of mice infected with Bordetella pertussis in a dose and time-dependent manner which suggests prophylactic and curative potentials of Cardisoma guanhumi extract against B. pertussis.