ArticlePDF Available

Abstract

Shell fishes like crustaceans and molluscs are often prone to shell diseases. Among crustaceans, crabs, lobsters and shrimps are largely infected by infectious pathogens and various environmental stresses. Viruses are commonly seen in shells of shrimps, whereas dinoflagellate is predominant in lobsters. Crabs are infected in higher extend than any other crustacean. Shell disease syndrome in brachyuran crabs is characterized by damaged external manifestation of colored lesions in the exoskeletons. Bacteria (Vibrio, Pseudomonas and Aeromonas), viruses (WSSV), fungi (yeast) and several other pathogens influence the higher percent of shell disease in crabs. Crabs with shell diseases are prone to internal damages causing variation in haemocyte counts and histopathological alteration in internal tissue and organs. Infections in crab may lead to great economic loss. This review discusses about the causes, types, histopathology, genetic variability, hematology, humoral defense mechanism and host susceptibility hypothesis of brachyuran crab shell diseases.
(a) (b)
(a) (b)
(a)
(b)
1 2 3
680
bp
... While strategically placed holes drilled through the carapace may avoid direct damage to internal structures, damage to the carapace may leave an individual susceptible to infection by an opportunistic pathogen leading to shell disease (Getchell 1989). Some species appear more affected than others, in particular brachyuran crabs (Joseph & Ravichandran 2012) and Homarus spp. lobsters (Davies et al. 2014). ...
Article
Full-text available
Decapod crustaceans are ecologically and economically important invertebrates but are vulnerable to anthropogenic pressures and climate change. Understanding their spatial ecology is essential for their management and conservation, with telemetry emerging as a useful tool to quantify space-use and movements. Here, we synthesize the use of telemetry to study decapods among articles published from 1971 to 2019 (n = 102 studies), by study species’ taxonomic group, study location, objectives, number of animals tagged and their tag recovery rate, types (and trends) of telemetry used, and IUCN conservation status. These studies revealed insight into the behaviours and roles of decapods across habitats and geographic regions. The most common study species were crayfish and lobsters (41%, Astacidea), and these studies also had the highest number of individuals tagged per study (mean = 149 individuals). Most studies (86%) were conducted in the northern hemisphere. Acoustic tags were the most commonly used equipment (66% of studies) and were first employed in 1971, followed by radio-telemetry (mid-1990s), passive integrated transponders (PIT; mid-2000s), and data storage tags (DST; late-2000s). Almost half (48%) of studies focused on species that had a conservation status of Least Concern, perhaps reflecting an applied science focus on animals of commercial interest rather than conservation importance. The positive allometric relationship between body length and movement rate (exponent = 0.86) demonstrates the type of broader ecological insight combining these studies can provide. Tracking decapod movements will likely become increasingly important for managing fisheries, protecting sensitive species, and understanding invasion biology.
... While strategically placed holes drilled through the carapace may avoid direct damage to internal structures, damage to the carapace may leave an individual susceptible to infection by an opportunistic pathogen leading to shell disease (Getchell 1989). Some species appear more affected than others, in particular brachyuran crabs (Joseph & Ravichandran 2012) and Homarus spp. lobsters (Davies et al. 2014). ...
Article
The cryptic nature of Homarus lobsters has restricted past behavioural studies to aquaria, mesocosms, or shallow coves. As such, spatial overlap and interactions between free-ranging Homarus lobsters have received little attention. However, it is clear that dominance behaviours directly affect their probability of capture, negatively affecting catch and complicating population monitoring. This study describes lobster behaviour at a scale that could not be achieved in aquaria or mesocosms. Home-range overlap and contact rates among free-ranging, acoustically tagged H. gammarus (n = 44) were assessed at multiple spatial scales. Data were analysed as unique pairings of lobsters (dyads), which could be single- or mixed-sex pairings. If home-range overlap between tagged lobsters occurred, interactions between lobsters were classified as attraction or avoidance. The number of times a lobster overlapped with the home range of another lobster was related to the mean substrate hardness within the home range of the focal lobster. Fewer interactions occurred between female lobsters, compared to males and mixed-sex pairings. Interactions between lobsters that occurred at 10 m, and interactions between mixed-sex pairs at 5 m, were identified as attractions. Interactions between male lobsters at 5 m were largely identified as avoidance and may indicate small-scale spatial exclusion. Understanding the drivers of movement and behaviour in wild free-ranging lobster populations is relevant to stock assessments, disease management, protected areas designation, and the development of sustainable evidence-based fisheries.
... Black spot disease is a bacterial infection that causes black lesions on the exoskeleton (Ayres & Edwards 1982). Exoskeleton lesions have been reported from many decapod crustaceans for three decades (Roald et al. 1981, Joseph & Ravichandran 2012, King et al. 2014. The potential impacts of the black spot disease and limb loss on the reproductive output and development of animals have not been investigated sufficiently yet. ...
Article
Full-text available
The brown crab is an important fishery resource in northern Europe. Understanding factors that affect fecundity in this species is complicated by the fact that ovigerous females enter traps infrequently. This study aimed to understand factors that affect brown crab fecundity and egg quality for crabs sampled from the waters around the Isle of Man. The size-fecundity relationship for the Isle of Man matched closely with those published for other geographical areas where a fishery exists for this species. Ovigerous crabs varied in size from 134 to 215 mm carapace width and each individual carried an estimated 0.4–3.0 million eggs. Fecundity was not affected by factors such as sampling season, location, loss of chelae, or black spot disease. Egg volume was independent of the number of eggs per batch or female body size. Egg volume was reduced significantly in crabs that had lost chelae. Egg dry weight, C and N composition did not vary with body size or any other explanatory factors such as chelal loss or the occurrence of black spot disease. Although the importance of the effect of claw loss on egg volume remains unclear, it may be an important consideration in fisheries in which the landing of claws is permitted.
... Crustacean shell disease, the progressive degradation of the chitinous exoskeleton through the secretion of chitinases and other enzymes by microorganisms, has been reported globally throughout the crustaceans. It is predominantly observed in large decapods such as lobsters (Gomez-Chiarri and Cobb, 2012) and crabs (Joseph and Ravichandran, 2012), and includes a number of commercially important species. It is most commonly identified by melanised lesions on the exoskeleton at the focal point of microbial attack (Getchel, 1989). ...
Article
Full-text available
Shell disease is the progressive degradation of a crustacean's exoskeleton through the secretion of chitinases and other enzymes from a suite of microorganisms. It affects a number of crustacean fisheries worldwide, through increased pre-capture mortality and rendering many individuals unsalable or with a reduced market value. The European edible crab (also known as the brown crab), Cancer pagurus Linnaeus, 1758, is highly susceptible to shell disease, but while intertidal populations have been comprehensively assessed, there has been little attention from a commercial fishery perspective. This study assessed the prevalence (% of catch infected) and severity (% cover of lesions on the carapace) of shell disease in the fishery around the Isle of Man for C. pagurus, in the Irish Sea. Shell disease was assessed in relation to sex and size, and the pattern of infection on ventral and dorsal surfaces described. A total of 2361 individuals was sampled between June and August 2012. Almost 25% of crabs were infected to some degree and of those infected an average of just over 2% of the carapace was covered by lesions. The proportion of individuals infected and the severity of infections was found to increase with size and was greater in males and those exhibiting limb losses. Differences in the pattern of lesions on the carapace between sexes suggest behavioural differences between genders can result in different patterns of individual infection. Both prevalence and severity of the disease varied considerably around the Isle of Man. Based on assessment of eight different fishing grounds, prevalence varied from as low as 15% of the population to as high as 35%, while the severity of infection varied between 0.8% to almost 3%. These findings not only suggest that shell disease syndrome could be causing a significant economic loss in the fishery, but also that environmental factors may be driving the condition. However, further investigation is required to fully elucidate the environmental drivers of this syndrome.
Article
Kepiting bakau (Scylla sp.) salah satu komoditas yang memiliki ekonomis tinggi. Salah satu faktor yang menyebabkan penurunan produksi kepiting adalah penyakit. Penyakit yang sering menyerang kepiting bakau adalah Vibriosis. Salah satu upaya dalam pengobatan dapat menggunakan bahan alami yaitu ekstrak daun api-api (A. marina) akan dilakukan pada salinitas yang berbeda. Tujuan dari penelitian ini adalah untuk mengetahui pengaruh salinitas terhadap efektifitas perendaman ekstrak daun api-api (A. marina) dilihat dari kelulushidupan, salinitas terbaik didalam perendaman ekstrak daun api-api (A. marina) kepiting bakau yang diinfeksi bakteri V. harveyi, dan gejala klinis kepiting bakau (Scylla sp.). Kepiting bakau yang digunakan dalam penelitian ini berjumlah 48 ekor dengan bobot 46-56 g. Penelitian ini menggunakan metode eksperimental dengan Rancangan Acak Lengkap (4 perlakuan 3 kali ulangan). Kepiting seluruhnya disuntik bakteri V. harveyi dengan kepadatan 0,1 x 107 CFU/ml pada bagian pangkal kaki renang. Pasca munculnya gejala klinis, kepiting bakau direndam menggunakan ekstrak daun api-api (A. marina) dengan perlakuan A (perendaman dalam salinitas 15 ppt), B (perendaman dalam salinitas 20 ppt), C (perendaman dalam salinitas 25 ppt), dan D (perendaman dalam salinitas 30 ppt). Kepiting yang digunakan adalah kepiting bakau, dengan kepadatan adalah 4 ekor/akuarium selama 14 hari. Data yang dianalisis adalah gejala klinis, kelulushidupan, histopatologi hepatopankreas dan kualitas air. Data yang telah didapatkan kemudian dianalisis seluruhnya secara deskriptif.Hasil penelitian menunjukkan salinitas tidak berpengaruh terhadap kelulushidupan kepiting bakau (Scylla sp.) yang di infeksi V. harveyi yang direndam ekstrak daun api-api pada berbegai salinitas, namun diperoleh nilai tertinggi pada salinitas 30 ppt (58%) dan terendah pada salinitas 15 ppt (50%). Salinitas terbaik untuk pengobatan menggunakan ekstrak daun api-api (A. marina) pada kepiting bakau (Scylla sp.) yang di infeksi bakteri V. harveyi adalah 30 ppt. Gejala klinis yang diperoleh dari hasil penelitian adalah perubahan morfologis dan perubahan tingkah laku. Hasil pengamatan histologi hepatopankreas ditemukan adanya kerusakan jaringan pada seluruh perlakuan yaitu berupa nekrosis, vakuolisis, dan degradasi lumen. Kualitas air pada media pemeliharaan berada dalam kisaran yang layak untuk kehidupan kepiting bakau.
Chapter
Although rare in natural populations of crustaceans, shell disease epizootics do occur from environmentally degraded coastal and estuarine waters. In aquaculture impoundments, shell disease can be a particular problem. This chapter will focus on the environmental aspects of shell disease in wild crustaceans, while aspects of bacterial and fungal pathogens associated shell disease and in aquaculture settings will be discussed in other sections. Two forms of shell disease have been described, one involving primary chitin digestion associated with microbes and an epizootic form in which chitin digestion is less important. The link between fecal, heavy metal, and insecticide pollution and shell disease remains to be proven conclusively. Shell disease begins when the epicuticle is breached by abrasion, injury, or enzymatic digestion, which exposes the chitinous layers to chitin-destroying microorganisms. The maintenance and repair of the epicuticle are considered critical in reducing the occurrence of cuticle erosions and stressors such as inadequate nutrition, temperature extremes, or onset of ecdysis result in higher rates of shell disease. Exposure to environmental pollutants can directly cause shell disease with no effect from chitinoclastic microorganisms.
Article
Full-text available
In this report are described abundance, size structure, and relative growth in Callinectes sapidus young stages from the Laguna El Llano blind estuary, Veracruz State (Mexico). Blue crabs were sampled in eight sampling sites since May 2013 to May 2014; four sites were located in un-vegetated, sandy bottom, and clear waters locations near to estuarine inlet, another four with fringe mangrove vegetation, muddy-bottom, and turbid waters. Were recorded pH, temperature, dissolved oxygen, turbidity, and salinity. A total of 276 organisms were collected (235 males and 41 females), young blue crabs were most numerous (91.3 %) in muddy-bottom, turbid waters sampling sites; the temporal abundance was not related statistically to hydrological variables (P >0.05). Were measured the Carapace Width (CW) and total weight (W) of each specimen, male CW ranked 12-85 mm and WW 0.3-123.4 g, while female CW was 9.0-92.8 mm and W 0.7-152.6 g; respect to total abundance, 76.4 % were 11-20 mm and 41-60 mm CW size class specimens; the relative growth was analyzed by using CW vs. W biometric relationship , for young blue crabs were negative allometric growth, regardless of sex; all specimens showed morphologically differentiated telson but early gonadal development stages; males outnumbered the gender proportion; 11-20 mm CW blue crabs occurrence through study span indicated continuous recruitment processes in this estuary.
Article
Full-text available
On the eastern seaboard of the United States, populations of the blue crab, Callinectes sapidus, experience recurring outbreaks of a parasitic dinoflagellate, Hematodinium perezi. Epizootics fulminate in summer and autumn causing mortalities in high-salinity embayments and estuaries. In laboratory studies, we experimentally investigated host mortality due to the disease, assessed differential hematological changes in infected crabs, and examined proliferation of the parasite. Mature, overwintering, nonovigerous female crabs were injected with 103 or 105 cells of H. perezi. Mortalities began 14 d after infection, with a median time to death of 30.3±1.5 d (SE). Subsequent mortality rates were greater than 86% in infected crabs. A relative risk model indicated that infected crabs were seven to eight times more likely to die than controls and that decreases in total hemocyte densities covaried significantly with mortality. Hemocyte densities declined precipitously (mean=48%) within 3 d of infection and exhibited differential changes in subpopulations of granulocytes and hyalinocytes that lasted throughout the course of the infection. Crabs that did not present infections after injection (i.e. 'immune' hosts) did not show hemocytopenia and exhibited significant long-term (21-27 d) granulocytemia. Detection of the parasite in the hemolymph of infected crabs increased from approximately 30% after 14 d to 60% after 21 d to 100% after 35 d. Plasmodial stages were, however, detectable in histological preparations of the heart within 3 days of infection and increased in number over 5 and 7 days. Sporulation of the parasite occurred over a short time (at least 4 d, after 43 d of infection) and did not culminate in the immediate death of the host. Hematodinium perezi represents a significant threat to the blue crab fisheries in high-salinity estuaries. Although the parasite infects male and female crabs, it may have a greater impact on mature females as they move to higher salinities to breed.
Article
The diversity of bacteria flora in skin, buccal cavity and gills of Lutjanus agennes, Pseudotolithus elongatus, Sphyraena barracuda from of Lagos lagoon were examined and compared. Different identification procedure and techniques (colonial morphology, isolation and culturing) were used to determine if pathogenic bacteria groups were present. Gram staining, motility, sugar fermentation as well as biochemical tests were also carried out. The bacteria isolated were Klebsiella spp. Proteus spp. Staphylococcus aureus, Citrobacter spp. Streptococcus pyogenes, Salmonella spp. Micrococcus spp. Bacillus licheniformis, Alcaligenes spp. Pseudomonas aerugenosa, Shigella spp. Enterobacter aerogenes, Escherichia coli and Serratia spp. from the skin, buccal cavity and the gill of randomly selected species. The bacterial count of L. agennes was highest in the buccal cavity (cfu = 10.9±0.2, f<0.05) than gills (cfu = 6.2±0.1, f<0.05) and skin (cfu = 4.2±0.3, f<0.05), P. elongates highest also in buccal cavity (cfu = 11.02±0.53, f<0.05) than gills (cfu = 6.2±0.2, f<0.05) and skin (cfu = 4.6±0.2, f<0.05), S. barracuda highest also in buccal cavity (cfu = 8.6±0.5, f<0.05) than gills (cfu = 5.6±0.1, f<0.05) and skin (cfu = 5.3±0.1, f<0.05). The bacteria flora isolated from the water sample were not totally different from the ones isolated from the fish except for Clostridium perfringenes, Staphylococcus epidermidis and Vibrio parahaemolyticus. The bacteria assemblage wereassemblages were of public health significance.
Article
Recent surveys of the Caribbean spiny lobster (Panulirus argus) in the Florida Keys and the Dry Tortugas revealed the presence of necrotic carapace lesions, which are commonly associated with bacterial shell disease in other crustaceans. To determine the etiology of these lesions, we obtained bacterial samples from diseased and nondiseased lobsters. Bacteria from these samples were isolated and identified by 16S ribosomal RNA sequencing. At least 600 bases of the 16S rRNA gene were aligned with sequences from known strains of marine bacteria. The analysis showed that the majority of the strains isolated from diseased and nondiseased lobsters are within the Vibrionaceae, a common family of marine bacteria. The majority of isolates identified as Vibrio species are clustered in a monophyletic group that does not include any of the known Vibrio species. Genbank BLAST analysis also confirmed these isolates as Vibrio and confirmed that they are not closely related to any known Vibrio species. These results suggest that the normal flora of P. argus is unique. The association of these bacteria both with lesions and with nondiseased animals suggests that the natural flora is responsible for the lesions seen in P. argus.
Article
Hemopoiesis in the Decapod crustacean Carcinus maenas occurs in the lymphocytogenic nodules of the gizzard walls. All blood cells, therefore, erive from a single cell line which proliferates in the nodules. The stem cells are called hemoblasts; they differentiate into circulating hemocytes and into cyanoblasts.Four kinds of homocytes have been identified: one agranulated and three different granulated cell types.The cyanoblasts are non-circulating blood cells. Their differentiation into mature cyanocytes is characterized by the synthesis and the accumulation of hemocyanin. The accumulated protein is probably released into the blood by a process similar to holocrine secretion.