Amazon River Prawn Macrobrachium Amazonicum Research Articles

Is there a trade-off between sperm production and sexual weaponry in the Amazon River prawn Macrobrachium amazonicum (Heller, 1862)?

The Amazon River prawn Macrobrachium amazonicum shows populations with four well-defined morphotypes in males. Dominant males of morphotypes green claw 1 (GC1) and green claw 2 (GC2) have large bodies and chelipeds and a higher reproductive success in comparison with the submissive morphotypes - translucent claw (TC) and cinnamon claw (CC). However, recently, some populations of the species do not have dominant morphotypes. Here, we compared the patterns of spermatic production and concentration among morphotypes and populations with three different phenotypes: (i) large-size amphidromous prawns, and (ii) large-size (“i” and “ii” with dominant morphotypes) and (iii) small-size hololimnetic prawns (without morphotypes). We described the spermatogenesis and the histochemical features of vasa deferentia (VD) and evaluated the relationship between the investment in spermatic production and sexual weapons acquisition in males of different phenotypes. The spermatic production and concentration in populations with four morphotypes were similar between morphotypes. The exception was the CC morphotype in which males had the seminiferous tubules filled with spermatocytes and low spermatic concentration. The spermatogenesis, spermiogenesis, and VD structure were not different among the studied phenotypes and populations. The seminal fluid of M. amazonicum is comprised by glycoproteins and by concentric layers of secretions of types I, II (basophilic), and III (eosinophilic). We could infer that males of dominant morphotypes allocate a higher amount of energy to the development of strong sexual weapons at the expense of the energy allocated to the reproductive system during the sequential growth. Inversely, small-size males direct more energy toward the spermatic production and transference at the expense of sexual weapons. Therefore, there is a clear trade-off between the investment in the gonadal and sexual weapons development in males of M. amazonicum.

Effect of Dietary Carotenoids on Reproducers of Amazon River Prawn Macrobrachium amazonicum. Part 1: Metabolism, Morphometric / Zootechnical Indexes, Body Composition and Gametes

The inclusion of natural extracts and solution of synthetic astaxanthin in the Macrobrachium amazonicum diet were tested to verify their effect on performance, body indexes and total accumulation of astaxanthin in the reproductive tissues and gametes of this crustacean in comparison with newly captured wild animals. The experiment was randomized in blocks (five treatments with three replicates). Four groups were submitted, during 20 days, to diets in recirculation tanks: control diet (CONT); diet containing natural extract of “buriti” (CAR); diet with inclusion of natural “urucum” extract (BIXN), diet with synthetic astaxanthin (ASTX) and NATURAL group (not fed with ration). 180 prawns were used, with 60 males (6.08±1.96 g) and 120 females (4.55±1.03 g) distributed in five groups containing four males and eight females each. There were no significant differences in performance and body indexes. The number of released spermatozoids, live spermatozoids, body and egg pigmentation was higher in BIXN and ASTX treatments. The ASTX treatment was superior to the NATURAL group in the body pigmentation of females and eggs and release of spermatophores by males. These results demonstrate that the use of natural and artificial carotenoid pigments in the diet are beneficial for reproduction of M. amazonicum.

Toxicity of Brazilian Medicinal Plant Extracts on Macrobrachium Amazonicum

Medicinal plants from Amazon have been commercialized for decades, but few scientific studies prove their effectiveness and safety in use in aquaculture activities. The objective of the present study was to use the Amazon river prawn Macrobrachium amazonicum to predict the toxicity of the natural extracts of nine medicinal plants viz pariri Arrabidaea chica, muirapuama Ptychopetalum olacoides, anauerá Licania macrophylla, barbatimão Ouratea hexasperma, faveira Vatairea guianensis, sacaca Croton cajucara, jacareúba Calophyllum brasilliense, pau d’arco Tabebuia sp. and verônica Dalbergia subcymosa, in concentrations of 1, 10, 100, 500 and 1000 µg/mL. The media was prepared in 0.5% dimethyl sulfoxide (DMSO) diluted with water. Ten post-larvae (0.5 ± 0.1 g) were added to each triplicate and, after 24 h, the mortalities were evaluated, with the results of median lethal concentration expressed as LC50-24h using the Probit statistical method. To obtain the concentrations of a common bioactive compound of plant extracts, the concentrations of flavonoids were analyzed using a methodology based on the formation of chromophores. The results of acute toxicity indicate variability in the toxic effects of medicinal plants, taking into account the concentration of total flavonoids, with the least toxic Tabebuia sp. (LC50 = 758.31 µg/mL) and the most toxic C. cajucara and V. guianensis (LC50 = 72.16 and 75.23 µg/mL), respectively. The extracts demonstrated lethality against M. amazonicum, which predicts toxicity and warns of its use them as herbal medicines. More studies must be carried out to determine other bioactive compounds in the plant extracts used since there is an unparalleled availability of chemical diversity.

Effect of Dietary Carotenoids on Reproducers of Amazon River Prawn Macrobrachium amazonicum. Part 2: External Coloration, Accumulation of Astaxanthin in Body Tissues and Pigment Stability in Feed

The color is an important factor to distinguish the commercialized Amazon river prawns. The accumulation of pigments in the body can vary according to the prawn’s diet. In this work, ethanolic extracts of “buriti” and annatto rich in pigments were obtained and tested comparatively with synthetic astaxanthin in the feeding of adults of Macrobrachium amazonicum, together with a control group without pigments and a newly captured wild group. Levels of body pigments were measured using UV reflective spectroscopy and external staining by colorimetry. Differences were observed in the accumulation of astaxanthin in body tissues, differences in saturation between genders and that annatto extract has greater stability in the feed after water immersion (P˂0.05). Further studies are recommended to verify the ideal dosage of natural pigments in relation to synthetic astaxanthin that benefits the productive development of prawns.

Effects of ammonia and nitrite on food consumption of the Amazon River prawn Macrobrachium amazonicum (Heller, 1862) postlarvae

Experiments were carried out to study the effects of ammonia and nitrite on food consumption of Macrobrachium amazonicum postlarvae. Postlarvae (average weight of 0.0625 g) were exposed during 21 days to four concentrations of total ammonia (0, 1.05, 2.1 and 4.2 mg. NH3+NH4+ L-1) and four concentrations of nitrite (0, 0.075, 0.15 and 0.30 mg N-NO2- L-1). After the exposure period, six prawns per treatment were maintained individually in 250 mL experimental units to analyze the food consumption as a function of the amount of food offered and the leftovers during a 24 h period. The food consumption presented significant alterations for prawns exposed to all nitrite concentrations and at concentrations of twice the recommended safety level for total ammonia. According to the results obtained, high concentrations of total ammonia and nitrite affect the food consumption of M. amazonicum adversely, influencing the species performance in culture systems.

Ultrastructure of two microsporidians Inodosporus sp. and Myospora sp. co-infecting muscles of the Amazon River prawn Macrobrachium amazonicum (Heller, 1862)

Abstract In the present study, we describe a co-infection of two microsporidians within the abdominal muscle of the Amazon River prawn Macrobrachium amazonicum from Brazil, detected through light and transmission electron microscopy and histopathological analysis. Two spore types and respective early developmental stages (meronts, sporonts, and sporoblasts) appeared grouped in numerous adjacent clusters among the muscle fibers of the host. Spores were initially divided into two morphotypes, Sp. 1 and Sp. 2, based on differences in shape, size, and internal organization. The Sp. 1 spores are pyriform to ovoid (4.3 ± 0.3 × 3.7 ± 0.4 µm in size) and resided in groups of eight within a sporophorous vesicle. Sp. 1 spores had bilayered walls and long tape-like external filaments with irregular morphology and size, forming a complex contiguous membranous system attached to the spore wall. The umbrella-like anchoring disc of the spores was in continuity with an anisofilar polar tube arranged in 7‒8 (rarely 9) coils. The Sp. 2 spores were rod-like in shape (3.1 ± 0.5 × 0.8 ± 0.1 µm in diameter) and the polar tube had 7‒8 coils. Their merogonic and sporogonic stages occurred within the sarcoplasm of the muscle cells in close contact with the myofibrils. Based on ultrastructural organization of the sporogonic stages, the Sp. 1 and Sp. 2 morphotypes probably belong to the genera Inodosporus and Myospora, respectively.

Combined and isolated effects of ammonia and nitrite on Amazon River prawn Macrobrachium amazonicum (Heller, 1862) juveniles

This study aimed to evaluate the combined effect of total ammonia and nitrite on Macrobrachium amazonicum juveniles exposed for 96 h. Juveniles (6.3 ± 0.7 cm and 1.79 ± 0.60 g; n = 640) were used in a completely randomized factorial design with four concentrations of total ammonia (0, 11, 22, and 44 mg.L−1) and four concentrations of nitrite (0, 1.5, 2.5, and 5 mg.L−1) with four replicates (n = 10) for each combination. Prawn gills were collected for histological evaluation and observation of damage to the organ (Iorg). The probit method was used to calculate the isolated LC50–96 h values for total ammonia and nitrite, the results indicated concentrations of 29.85 and 2.49 mg.L−1, respectively. The LC50–96 h of the combined compounds was 20.87 mg.L−1 for total ammonia and 2.95 mg.L−1 for nitrite. The isolated safety levels of total ammonia and nitrite were 2.98 and 0.25 mg.L−1, while for the combined treatments the safety level was 2.08 mg.L−1 for total ammonia and 0.29 mg.L−1 for nitrite. Calculating the sum of additivity and the additivity index of the mixture showed the effect of the combined compounds is 0.88 times lower than the sum of the isolated effects, thus an antagonistic effect. That is reinforced by histological analysis of gills, with reduced gill damage in the combined treatments. In conclusion, M. amazonicum showed greater tolerance to total ammonia and nitrite concentrations when they were combined (antagonistic effect) rather than when subjected to the isolated compounds (total ammonia and nitrite) for 96 h.

Effects of environmental light colors on the larviculture of the Amazon River prawn Macrobrachium amazonicum

This study aimed to investigate the effects of red, yellow, green, violet, blue, and white light in Macrobrachium amazonicum larviculture. The trials were composed of six treatments (i.e., colors red, yellow, green, blue, violet, and white light in tanks) with four replicates each. Transparent tanks of 1 L of water, 10 salinity, and 2400 newly hatched larvae were used in trials. The larvae were fed Artemia salina nauplii and complemented with commercial shrimp feed daily. The light color affected the temperature, pH, and dissolved oxygen in the water culture and nauplii consumption, survival, and productivity of M. amazonicum. In the tanks with red light, the mean temperature was lower, while the oxygen and pH levels were higher than those with other colors. The mean consumption of A. salina nauplii was 15% higher by M. amazonicum in tanks with blue and violet light than red light. No difference in larval development was observed; however, larvae cultured under white light completed the larval cycle four days earlier than those cultured under red light. The productivity of larvae cultivated under white and violet light was 45% greater than larvae cultured under red light, and the survival was > 75%. Results indicated that M. amazonicum larval cultivation should be performed in tanks under bright light, preferably white, since other colors may negatively affect the larval development.

Sperm count of Macrobrachium amazonicum (Heller, 1862) populations with distinct life histories, with introduction of a simple counting method

Sperm count is an important quality assessment tool in farming programs and stock improvement in crustaceans. However, this procedure is still little used in caridean shrimps and standardization of appropriate techniques for the group is lacking. In this study, we propose a simple protocol adapted to determine sperm count in carideans using as model the Amazon River prawn Macrobrachium amazonicum. Males of dominant morphotypes (GC1 and GC2) of this species with amphidromous and hololimnetic life cycles were collected and carefully dissected. The ejaculatory duct was removed from the vas deferens and dissociated in a solution of distilled water (9μl) and methylene blue (1μl). Subsequently, 1μl of this new solution was added to distilled water (9μl), and then 1μl was pipetted and quantified in a Neubauer chamber. The feasibility of this technique was also evaluated in animals preserved (5–480days) in 70% ethanol from collections and the structural morphology of spermatozoa (spz) was examined. Despite morphometric differences observed between different types of males, the mean sperm count was similar for the species. In amphidromous animals, 60,258spz/μl were registered for GC1 and 65,308spz/μl for GC2, while in hololimnetic prawns, 48,950spz/μl were registered in GC1 and 53,850spz/μl in GC2. The variation in sperm count among animals preserved for different periods of time was small and very similar to those of fresh animals. Also, no microscopic changes in the structures of spz were observed. This technique can be applied to obtain a spermiogram in fresh as well as preserved animals, being especially important in studies with animals examined in population studies and deposited in collections or laboratories. This protocol can be used as a general model for spermiogram in caridean shrimps due to the great similarity of male reproductive systems within the group.

Morphometric discrimination among three stocks of Macrobrachium amazonicum in the Brazilian Amazon

• This study evaluated morphometric variation among three stocks of Amazon river prawn Macrobrachium amazonicum . • Different characteristics at the stock-level between sexes were observed. • Stocks differences were proportional to distance between sites. The aim of this study was to compare stocks of Amazon River prawns ( Macrobrachium amazonicum ) among 3 sampling sites (Tucuruí, Cametá and Soure) in the Tocantins/Araguaia River Basin (Amazônia, Brazil) through morphometric analyses. A total of 360 specimens (180 males and 180 females) were sampled, and 21 morphometric characters were assessed and subsequently analyzed using descriptive and multivariate statistics. Principal component analyses showed a strong ability to distinguish the different stocks, especially between those at the sites most distant from each other (Tucuruí and Soure). In the discriminatory analysis, the most significant characteristics for females were total length (TL), carapace width (Cw) and palm width (Pw), whereas for males, the most significant characteristics were Pw and Cw. The cluster analysis showed different groupings for the male and female models, although the Tucuruí and Soure stocks were always separated. Therefore, the multivariate analyses identified 3 different stocks in the sampled area, and an explicit fishing management plan for each stock is suggested because this species has been shown to be imminently threatened by overfishing in the Amazon region.

Effects of feeding strategy on larval development of the Amazon River prawn Macrobrachium amazonicum

ABSTRACT Effects of four feeding regimes on the development and feed intake, survival, productivity, and growth of Macrobrachium amazonicum larvae were investigated. Larvae were fed from stage II to IX, as follows: Artemia nauplii + inert diet during the entire larval cycle (AIn); Artemia nauplii for the entire larval cycle + inert diet from stage V onward (A/AIn); Artemia nauplii until stage IV + inert diet from stage IV onward (A/In); and only inert diet for the entire larval cycle [...]

Acute Toxicity of Nitrite to Various Life Stages of the Amazon River Prawn, Macrobrachium amazonicum, Heller, 1862.

This study determined the effects of nitrite on different life stages of the Amazon river prawn Macrobrachium amazonicum. Prawns of each life stage (postlarvae, juveniles and adults) were stocked in 24 experimental units (n = 10 prawns), under a complete randomized design. Individuals were exposed to nitrite (0, 1, 2, 4, 8 and 16mgL-1). The median lethal concentration after 96h (96h LC50) was calculated through the Weibull I. The mortality results showed that M. amazonicum is slightly less tolerant to nitrite than other species of Macrobrachium. The 96h LC50 for postlarvae, juveniles and adults of M. amazonicum were of 1.49, 2.36 and 2.34mgnitrite/L, respectively. Nitrite intoxication risk quotient suggest moderated risk to low risk to the species. Usually in production systems nitrite values are lower than safe levels suggested in this study (0.1mgL-1 to postlarvae and 0.2mgL-1 nitrite to juvenile and adults), which makes our results appropriate for the production of this species.

Acute toxicity of ammonia to various life stages of the Amazon river prawn, Macrobrachium amazonicum, Heller, 1862

The buildup of nitrogenous wastes in the water reflects biological processes potentially stimulated by organic pollution. These wastes may cause physiological harm and even mortality in produced aquatic species. This study aimed at determining the effects of ammonia on different life stages of the Amazon river prawn Macrobrachium amazonicum. Experimental set-up used 240 prawns to each life stage (post-larvae, juveniles and adults), stocked in 24 experimental units, under a totally casualized arrangement, for each life stage. Individuals were exposed to 6 different concentrations of total ammonia (0, 5, 10, 20, 40 and 80mg·L−1), and the mean lethal concentration after 96h was determined (LC50-96h). Water oxygen, pH, and temperature were monitored daily; at the start and end of the experimental periods, hardness, alkalinity, ammonia, nitrite and nitrate were also measured. LC50-96h was calculated through the probit method, later submitted to a linear regression (p<0.05). LC50-96h for post-larvae, juveniles, and adults of M. amazonicum was of 21.14, 21.65 and 36.59mg·L−1 of total ammonia, or 0.67, 0.75 and 1.08mg·L−1of non-ionized ammonia. Thus, from these results, safe levels for the production of this prawn are of 0.06, 0.07 and 0.1mg·L−1, from post-larvae, juveniles and adults, respectively.

The ultrastructural evaluation of digestive cells in the hepatopancreas of the Amazon River prawn,Macrobrachium amazonicum

The Amazon River prawn Macrobrachium amazonicum is endemic to tropical South America and is being intensively exploited by artisanal fisheries in Brazil. Limited information is available about the nutritional requirements of M. amazonicum, although the production of this species is now technically feasible. The digestive process in this species is still unclear and investigation into the digestive cells of its hepatopancreatic epithelium is required. Thus, the hepatopancreas from 15 specimens were fixed in Karnovsky Solution and processed for Transmission Electron Microscopy. Our results indicate that E cells are located at the distal portion of the hepatopancreatic tubule and are involved in mitotic activity. The cylindrical R cells are sparse and are only found in the proximal portion of the hepatopancreatic tubule. According to its ultrastructural characteristics, this cell is involved in pinocytosis. M cells are generally found near the R cells. The F cells are scattered throughout the length of the hepatopancreatic tubules, and B cells are observed mainly in the proximal and middle regions. F cells and B cells are likely related to, respectively, the synthesis of enzymes and the intracelular digestion. R- and M cells are probably related to material storage. Thus, these findings provide basic information on the cell types that perform protein digestion in M. amazonicum, and will be useful in further nutritional research. The identification and characterization of digestive cells is an important step towards understanding the digestive mechanisms.

Temporal variation in the water quality of ponds and effluent of grow-out ponds of Amazon River prawn Macrobrachium amazonicum

This study was conducted in the Crustacean Sector of the Aquaculture Center (CAUNESP) at the São Paulo State University, Jaboticabal (21 ° 15’22”S and 48 ° 18’48”W) São Paulo, Brazil, from December 2003 to May 2004. The aim was to examine the water quality parameters of importance to freshwater prawn culture, operated in a semi-intensive system in Amazon River. Nine 0.01-ha earthen ponds were stocked with 20 juveniles.m -2 . Prawns were fed commercial diet at a rate of 7 to 9% of biomass until the 14th week. After 145 days of stocking, all ponds were drained and harvested. The following water parameters were determined weekly: dissolved oxygen, oxygen biochemical demand, pH, total alkalinity, electrical conductivity, suspended total solids and turbidity, N-nitrate, N-nitrite, N-nitrogen ammonia, N- total, soluble ortophosphate, total phosphorus, chlorophyll and pheophytin. In the semi-intensive culture system of M. amazonicum, there was no clear pattern of temporal variation in the limnological variables studied. Dissolved oxygen, pH, BOD, ammonia nitrogen and nitrate increased in the afternoon period while, the other variables did not change. In general, water quality is more dependent on the biological processes that occur in the pond than on the characteristics of the renewal water for some variable.

Transportation of Amazon river prawnMacrobrachium amazonicumjuveniles in different biomass densities

Aquaculture ResearchVolume 45, Issue 7 p. 1264-1268 Short Communication Transportation of Amazon river prawn Macrobrachium amazonicum juveniles in different biomass densities Luciane Sperandio, Corresponding Author Luciane Sperandio São Paulo State University – Aquaculture Center, Jaboticabal, SP, BrazilCorrespondence: L. Sperandio, Sperandio Instituto Federal Goiano, Campus Urutaí, Rodovia Geraldo Silva Nascimento, km 2,5 Zona Rural, Urutaí – GO. Zip code 75790-000. E-mail: [email protected]Search for more papers by this authorMichael Bernard New, Michael Bernard New Aquaculture without Frontiers, Wroxton Lodge, Marlow, Bucks, UKSearch for more papers by this authorWagner Cotroni Valenti, Wagner Cotroni Valenti São Paulo State University – UNESP, São, Vicente, SP, BrazilSearch for more papers by this author Luciane Sperandio, Corresponding Author Luciane Sperandio São Paulo State University – Aquaculture Center, Jaboticabal, SP, BrazilCorrespondence: L. Sperandio, Sperandio Instituto Federal Goiano, Campus Urutaí, Rodovia Geraldo Silva Nascimento, km 2,5 Zona Rural, Urutaí – GO. Zip code 75790-000. E-mail: [email protected]Search for more papers by this authorMichael Bernard New, Michael Bernard New Aquaculture without Frontiers, Wroxton Lodge, Marlow, Bucks, UKSearch for more papers by this authorWagner Cotroni Valenti, Wagner Cotroni Valenti São Paulo State University – UNESP, São, Vicente, SP, BrazilSearch for more papers by this author First published: 06 December 2012 https://doi.org/10.1111/are.12079Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Volume45, Issue7June 2014Pages 1264-1268 RelatedInformation

Current status and prospects of farming the giant river prawn (Macrobrachium rosenbergii (De Man 1879) and the Amazon river prawn Macrobrachium amazonicum (Heller 1862)) in Brazil

This article describes some aspects of the current status of Macrobrachium rosenbergii (De Man 1879) and Macrobrachium amazonicum (Heller 1862) farming in Brazil, including a brief description of the technologies used. A history of the farming of M. amazonicum is provided, together with the marketing strategies currently employed for freshwater prawns in Brazil and future trends. It was concluded that freshwater prawn farming in Brazil currently has a favourable scenario for expansion due to increasing demand and to prospects of an improved organization of the productive chain.

Spatial distribution of the amazon river prawn Macrobrachium Amazonicum (Heller, 1862) (Decapoda, Caridea, Palaemonidae) in two perennial creeks of an estuary on the northern coast of Brazil (Guajará Bay, Belém, Pará)

Macrobrachium amazonicum is the most frequently consumed freshwater crustacean by river communities of the Amazon. Despite its relative abundance and vast knowledge on the species from data on cultivated specimens, little is known regarding its biology in the natural environment, especially its use of creeks that are strongly influenced by the tide. Specimens of Macrobrachium amazonicum were collected in September 2006 (dry season) and March 2007 (rainy season) from two perennial creeks of the Guajará Bay in the state of Pará (northern Brazil), using traps similar to the matapis used by local fishermen to identify the spatial distribution of the species. Shrimps of all sizes use the tidal creeks in both seasons, including for breeding purposes. The greatest abundance of the species occurred in headwater areas and in the dry season. It is suggested that abundant allochthonous organic matter and the preference for protected areas may explain the abundance and breeding activity of this species in the headwaters of the creeks.

Effect of density on population development in the Amazon River prawn Macrobrachium amazonicum

The Amazon River prawn Macrobrachium amazonicum is widely distributed in lentic and lotic environments of South America, and shows different male morphotypes. In the present study, the effect of crowding on the general population structure of this species and its variation over time were evaluated. Prawns were reared in mesocosms consisting of 12 rectangular ~100 m 2 earthen ponds for ~160 d at densities of 10, 20, 40, and 80 prawns m -2 . Prawn density affected both individual and population development. Increased density reduced the size and frequency of the largest male morphotypes and reproductive females, delayed female maturation, and enhanced the asymmetry of the size distribution of individuals, increasing the frequency of smaller prawns. Although mortality was not affected up to 80 ind. m -2 , individual growth rate and reproductive potential decreased at high densities (≥40 ind. m -2 ). Therefore, the ontogeny and population development after metamor- phosis are density-dependent processes. In conclusion, M. amazonicum has a dynamic and density- dependent population structure. This may be due to intrinsic regulatory mechanisms of the species and/or intraspecific competition. It seems that shifts in the sex ratio and the development pattern of male morphotypes are traits which evolved as part of the life strategy to decrease intraspecific com- petition in crowded conditions and to maintain a large population size.

The invasion of five alien species in the Delta do Parnaíba Environmental Protection Area, Northeastern Brazil

Marine biological invasions have been regarded as one of the major causes of native biodiversity loss, with shipping and aquaculture being the leading contributors for the introductions of alien species in aquatic ecosystems. In the present study, five aquatic alien species (one mollusk, three crustaceans and one fish species) were detected during dives, shore searches and from the fisheries on the coast of the Delta do Parnaíba Environmental Protection Area, in the States of Piauí and Maranhão, Northeastern Brazil. The species were the bicolor purse-oyster Isognomon bicolor, the whiteleg shrimp Litopenaeus vannamei, the giant river prawn Macrobrachium rosenbergii, the Indo-Pacific swimming crab Charybdis hellerii and, the muzzled blenny Omobranchus punctatus. Ballast water (I. bicolor, C. hellerii, and O. punctatus) and aquaculture activities (L. vannamei and M. rosenbergii) in adjacent areas are the most likely vectors of introduction. All exotic species found have potential impact risks to the environment because they are able to compete against native species for resources (food and habitat). Isognomon bicolor share the same habitat and food items with the native bivalve species of mussels and barnacles. Litopenaeus vannamei share the same habitat and food items with the native penaeids such as the pinkspot shrimp Farfantepenaeus brasiliensis, the Southern brown shrimp Farfantepenaeus subtilis, and the Southern white shrimp Litopenaeus schmitti, and in the past few years L. vannamei was responsible for a viral epidemics in the cultivation tanks that could be transmitted to native penaeid shrimps. Charybdis hellerii is also able to cause impacts on the local fisheries as the species can decrease the populations of native portunid crabs which are commercialized in the studied region. Macrobrachium rosenbergii may be sharing natural resources with the Amazon River prawn Macrobrachium amazonicum. Omobranchus punctatus shares habit with the native redlip blenny Ophioblennius atlanticus and other fishes, such as the frillfin goby Bathigobius soporator Some immediate remedial measures to prevent further introductions from ballast water and shrimp farm ponds should be: (i) to prevent the release of ballast water by ship/vessels in the region; (ii) to reroute all effluent waters from shrimp rearing facilities through an underground or above-ground dry well; (iii) to install adequate sand and gravel filter which will allow passage of water but not livestock; (iv) outdoor shrimp pounds located on floodable land should be diked, and; (v) to promote environmental awareness of those directly involved with ballast water (crews of ship/vessels) and shrimp farms in the region.