Shrimp Abundance Research Articles

Full-length 16S rRNA amplicon sequencing reveals the variation of epibiotic microbiota associated with two shrimp species of Alvinocarididae: possibly co-determined by environmental heterogeneity and specific recognition of hosts.

Shrimps of the family Alvinocarididae, endemic species to deep sea chemosynthetic ecosystems, harbor epibiotic microbes on gills which probably play important roles in the survival of the shrimps. Among them, Alvinocaris longirostris and Shinkaicaris leurokolos occupy different ecological niches within the same hydrothermal vent in Okinawa Trough, and A. longirostris also exists in a methane seep of the South China Sea. In this study, full-length 16S rRNA sequences of the gill associated bacteria of two alvinocaridid species from different chemosynthetically ecological niches were first captured by single-molecule real-time sequencing. Totally, 120,792 optimized circular consensus sequences with ∼1,450 bp in length were obtained and clustered into 578 operational taxonomic units. Alpha diversity analysis showed seep A. longirostris had the highest species richness and evenness (average Chao1 = 213.68, Shannon = 3.39). Beta diversity analysis revealed that all samples were clearly divided into three groups, and microbial community of A. longirostris from seep and vent were more related than the other comparisons. By permutational multivariate analysis of variance, the most significant community compositional variance was detected between seep A. longirostris and vent S. leurokolos (R2 = 0.731, P = 0.001). The taxon tags were further classified into 21 phyla, 40 classes, 89 orders, 124 families and 135 genera. Overall, the microbial communities were dominated by Campylobacteria and Gammaproteobacteria. Alphaproteobacteria, Bacteroidia, Verrucomicrobiae, Bacilli and other minor groups were also detected at lower abundance. Taxonomic groups recovered from the vent S. leurokolos samples were only dominated by Sulfurovaceae (94.06%). In comparison, gill-associated microbiota of vent A. longirostris consisted of more diverse sulfur-oxidizing bacteria, including Sulfurovaceae (69.21%), Thiotrichaceae (6.77%) and a putative novel Gammaproteobacteria group (14.37%), while in seep A. longirostris, Gammaproteobacteria un-group (44.01%) constituted the major component, following the methane-oxidizing bacteria Methylomonadaceae (19.38%), and Sulfurovaceae (18.66%). Therefore, the gill associated bacteria composition and abundance of alvinocaridid shrimps are closely related to the habitat heterogeneity and the selection of microbiota by the host. However, the interaction between these alvinocaridid shrimps and the epibiotic communities requires further study based on metagenome sequencing and fluorescence in situ hybridization.

Growth Performance, Immune-Related and Antioxidant Genes Expression, and Gut Bacterial Abundance of Pacific White Leg Shrimp, Litopenaeus vannamei, Dietary Supplemented With Natural Astaxanthin.

The current study examines the effect of dietary supplementation of ethanolic extract of Arthrospira platensis NIOF17/003, which is mainly natural astaxanthins (97.50%), on the growth performance, feed utilization, bacterial abundance, and immune-related and antioxidant gene expressions of the Pacific white leg shrimp, Litopenaeus vannamei. A total of 360 healthy L. vannamei postlarvae (0.19 ± 0.003 g) were divided into four groups (0, 2, 4, and 6 g natural astaxanthins/kg diet) each in three replicates, at an initial density of 30 PLs per tank (40 L capacity). The shrimp were fed the tested diets three times a day at a rate of 10% of their total body weight for 90 days. Diets supplemented with different astaxanthin levels significantly improved shrimp growth performance and feed conversion ratio compared to the control diet. No significant differences were observed in survival rates among all experimental groups. The immune-related genes (prophenoloxidase, lysozyme, beta-glucan binding protein, transglutaminase, and crustin) mRNA levels were significantly upregulated in groups fed with different concentrations of the natural astaxanthins in a dose-dependent manner. The prophenoloxidase gene is the highest immune-upregulated gene (14.71-fold change) in response to astaxanthin supplementation. The superoxide dismutase mRNA level was significantly increased with increasing dietary astaxanthin supplementation. In addition, increasing astaxanthin supplementation levels significantly reduced the count of heterotrophic bacteria and Vibrio spp. in the culture water and shrimp intestine. Overall, the current results concluded that diet supplementation with natural astaxanthin, extracted from Arthrospira platensis, enhanced the growth performance, immune response, and antioxidant status of L. vannamei.

The Optimization of Dietary Protein Level and Carbon Sources on Biofloc Nutritive Values, Bacterial Abundance, and Growth Performances of Whiteleg Shrimp (Litopenaeusvannamei) Juveniles.

A biofloc technology-based 75-day indoor growth trial in an 80 L glass aquaria was conducted to evaluate the effects of two different carbon sources (sugarcane bagasse, SB, and wheat flour, WF) on the biofloc composition, bacterial abundance, and growth of whiteleg shrimp (Litopenaeus vannamei) juveniles (0.23 ± 0.04 g). Three different levels of dietary protein content (250, 300, and 350 g protein kg−1 diet) and two carbon sources (SB and WF) were applied (SB250, WF250, SB300, WF300, SB350, and WF350, respectively), comparing to a controlled diet without biofloc and fed on a 450 g protein kg−1 diet (C450). With the addition of SB and WF, water quality was in the ideal recommended ranges for L. vannamei culture. At the end of the experiment, the biofloc volume increased with increasing dietary protein levels. The nutritional value of biofloc in different treatments was influenced by dietary protein and added SB and WF. Increasing dietary protein significantly increased the protein and lipid contents of the produced biofloc. The use of WF as a carbon source significantly increased lipids and nitrogen-free extract in the biofloc. The total heterotrophic bacterial (THB) count was significantly higher (p < 0.05) in WF300 and WF350 than in the other treatments. The mean effect of the protein levels and carbon source was significantly reported, whereas the highest significant THB count was recorded with 300 dietary protein and using WF as a carbon source. The growth performances of L. vannamei fed with biofloc treatments were significantly (p < 0.05) higher than the C450 group. The highest final weight and weight gain were recorded in SB350 treatment. The feed conversion ratio was not affected by reducing dietary protein levels; meanwhile, the protein efficiency ratio increased significantly in biofloc treatments than in the control. Overall, the results demonstrate that, compared to the control treatment of 450 dietary protein, the biofloc treatments using WF as a carbon source could compensate for the reduction in the dietary protein levels in the diet of L. vannamei and maintain higher zootechnical performance.

Demographic and Trophic Analysis of Adult Grass Shrimp (Palaemonetes pugio) from Living Shoreline and Natural Tidal Marshes in the Chesapeake Bay

With extensive and ongoing human development in coastal areas, effective shoreline-protection strategies against erosion and rising sea level that also provide natural ecosystem services will become increasingly important. Constructed living shoreline marshes can serve as successful management solutions when implemented correctly, but studies comparing these created estuarine habitats to their natural marsh counterparts are needed to assess their ecological functionality. We compared adult Palaemonetes pugio (Daggerblade Grass Shrimp) population demographics and diets from 13 pairs of living shoreline and natural marsh sites in the southwestern portion of the Chesapeake Bay. No significant differences were observed in demographics including abundance, weight, length, number of gravid females, and egg abundance and quality. Gut-content analysis detected significantly more terrestrial debris in shrimp from living shorelines, but the omnivorous dietary needs appeared met in all marsh sites. Overall, shrimp populations differed more among site pairs from different shorescape settings than between created and natural marshes from the same settings, suggesting that living shorelines are approaching ecosystem functionality similar to natural marsh habitats. However, the observed negative effect of agricultural land use on shrimp abundance and the discovery of microplastics in gut contents from all sites sampled indicate the need for further consideration of human impacts in both constructed and natural coastal habitats.

Effects of harvesting on subtidal kelp forests (Lessonia trabeculata) in central Chile

AbstractThe systematic degradation of marine ecosystems is a global phenomenon that has important and diverse consequences including biodiversity loss and reduced ecosystem service provisions. In temperate regions, subtidal kelp forests are dominant ecosystems in rocky coasts, subjected to the influence of local‐scale stressors and regional environmental variation. For example, kelps within the Humboldt Current System are at risk of degradation from live‐harvesting by fisheries. However, limited information exists regarding the long‐term consequences of kelp harvesting, which, in turn, limits the ability to provide effective management and conservation efforts. Here, we examined the ecosystem‐level consequences of the artisanal subtidal Lessonia trabeculata fishery along the coast of central Chile during a 2‐year period, assessing (1) the change in adult and juvenile L. trabeculata density within harvested and nonharvested (control) plots (~90 m2), (2) the impact of L. trabeculata harvesting on reef fish and macroinvertebrate assemblages, and (3) the change in density of the most abundant L. trabeculata‐associated species. The experiment was conducted over a 2‐year period, from December 2016 to May 2019. Approximately 90% of L. trabeculata was removed by an experienced kelp fisherman in experimental plots. After 2 years, L. trabeculata and its associated community showed a lack of recovery in the harvested plots. Within these plots, the average abundance of the rock shrimp, Rhynchocinetes typus, and the herbivorous snail, Tegula tridentata, was greater than in nonharvested plots and the pattern persisted over the study period. The difference in abundance of associated species may be key to the (lack of) recovery of L. trabeculata forests. Our study highlights the impact of L. trabeculata harvesting on associated fauna; however, significant knowledge gaps remain regarding the capacity and time frame to reestablish the original biomass of L. trabeculata, as well as its associated fauna. The management of L. trabeculata fisheries needs to account for ecosystem‐wide impacts in order to better manage and protect vital coastal ecosystems.

Seasonal Abundance and Length Patterns of Brown and White Shrimp in Texas Estuaries and Nearshore Waters: Implications for Population and Fishery Dynamics

AbstractPenaeid shrimp are a major contributor to commercial landings in the Gulf of Mexico, with white shrimp Litopenaeus setiferus and brown shrimp Farfantepenaeus aztecus making up the bulk of the landings off Texas. In this study, we examined seasonal trends in white and brown shrimp population demographics (relative abundance, monthly proportion of catch, and length) and their relationship with water quality parameters (water temperature and salinity) across a 36‐year fishery‐independent data set for Texas estuarine and nearshore waters. The primary findings of this analysis were consistent negative trends in seasonal mean TL (April–August) for brown shrimp. These negative trends resulted in decreases in mean TL of up to 20 mm across the time series. Additionally, growth coefficients calculated on an annual scale for brown shrimp showed negative trends as well. White shrimp did not show the same consistently negative trends in mean length or growth. Although expected seasonal trends in CPUE and monthly proportions of catch were observed, the analysis showed few convincing or consistent annual trends in these metrics for either species. We suggest that the differing trends in mean length (i.e., between species) may be explained by summer water temperatures exceeding the optimum growth range for brown shrimp in the latter part of the time series examined here. Such trends in mean length for the brown shrimp population may have implications for population fecundity and may affect the value and efficiency of shrimp harvest in commercial fisheries, though this has yet to be seen. Nevertheless, managers should remain vigilant to any continued negative trends in brown shrimp length and their potential impact on the population and fishery dynamics.

Natural resource-use in the Lower Tana River Delta based on household surveys and remote sensing of land cover and land use patterns

Household survey data and spatially explicit Sentinel-2 satellite images of land cover and land use during the dry and wet seasons were used to investigate livelihood strategies in the Lower Tana River Delta in Kenya, where food security and economic activity rely almost exclusively on ecosystem goods and services. Land cover classification of satellite imagery successfully showed seasonal changes to estuary-related vegetation and habitats from which land use cycles could be inferred. Flood-recession agriculture and part-time fishing were the most common activities at Ozi village, some 10 km upstream from the estuary mouth, whereas full-time fishing dominated activities at Kipini town, where the Tana Estuary discharges into Ungwana Bay. Seasonality of fishing at Kipini depended on favourable sea conditions, arrival of migrant fishers and peaks in shrimp abundance. Seasonality of agriculture at Ozi depended on the freshwater flooding regime, visible in satellite images as an inverse relationship of areas covered by wetlands and cultivated lands. The predominance of fishing assets at Kipini indicated specialization, which underlies a socio-economic network of fish processing, marketing, distribution and logistical support services. In contrast, mixed farming assets and traditional fishing gear at Ozi reflected more diversified farmer-fisher livelihoods, as a risk avoidance strategy. Key outcomes of this study were that land cover and land use were strongly seasonal, that coastal and upstream communities in the Tana Estuary relied on different combinations of ecosystem goods and services, and that livelihood strategies at the two locations differed fundamentally. Combining social, spatial and ecological data to describe socio-ecological systems typical of the Tana Estuary provided a broad platform for shared resource management strategies.

Length-weight relationship of Penaeus indicus and Penaeus merguiensis in the Langsa mangrove area, Aceh Province

The two Penaeid shrimps Penaeus indicus and Penaeus merguiensis are the most common commercial species found in the Langsa mangrove forest. The growth pattern of these two Penaeid shrimps are strongly influenced by environmental factors such as temperature, pH, dissolved oxygen (DO), salinity, availability of food and predators, which ultimately determines the abundance and catch of commercial adult shrimps obtained. The present study aims to investigate the length-weight relationship of P. indicus and P. merguiensis in the Langsa mangrove forest, Aceh Province. The sampling was conducted in November 2018 with the stratified random sampling method. A total of 124 shrimps consisted of 92 samples P. indicus and 32 samples P. merguiensis. The results showed that growth pattern of two Penaeid shrimps was categorized as negative allometric. The highest b value is shown in P. merguiensis with b value of 2.87 while P. indicus 2.55. The value of the relative weight condition factor (Wr) of the two shrimps indicates a value of >100. It is concluded that the waters of the mangrove forest in Langsa City are still able to support the survival of P. indicus and P. merguiensis.

Density and Relativity Abundance of the Prawn and Shrimps in Al-Hammar and Al-Chibayish Marshes of Southern Iraq

The current study was conducted to calculate the annual Occurrence, monthly density and relative abundance of the Metapenaeus affinis. The samples were collected monthly for the period from October 2017 to September 2018. Some environmental factors such as temperature of water and air, pH, salinity, dissolved oxygen and turbidity were measured. We obtained 7 types of shrimp belonging to three families in the Al-Burka station and the Al Sabbaghia Station , which are 7 species, all of which belong to the Division of arthropods and crustaceans, the first family: Penaeidae is a banyan family that includes Metapeneaus affinis, Penaeus semisulcatus, Family: Atyidae, include Caridina babaulti basrensis , Atyaephyra desmaresti mesopotamica and Family: Palamonidae includes Exopalaemon styliferus, Palaemon elegans and Macrobrachium nipponense divided into four categories according to the Yearly Occurrence Resident, Fluctuated, Occasional, Rare .&#x0D; The monthly density of each species of shrimp was calculated and the range was: for Metapenaeus affinis 0-325.85 Ind./ m² and Penaeus semisulacatus 0-5.32 Ind./ m² and Caridina babaulti basrensis 0-111.72 Ind./ m² Atyaephyra desmaresti mesopotamica 0-679.63 Ind./ m² Exopalaemon styliferus 0-23.94 Ind./ m² Palaemon elegans 0-19.95 Ind./m² Macrobrachium nipponense 0-55.86 Ind./ m² .&#x0D; The highest density in the Al-Burka station for Metapeneaus affinis to 2600.15 Ind./ m² The Lowest density for Penaeus semisulacatus to 9.31 Ind./ m² and the highest density in the Al Sabbaghia Station for cardinia babaulti basrensis to 320.53 Ind./ m² and the lowest density for Exopalaemon styliferu at 3.99 Ind./ m² and The total density of the Al-Burka station in the east Al-Hammar Marsh was higher than the. Al Sabbaghia Station In Chabaish Marsh .&#x0D; The monthly abundance of shrimp was calculated as Metapenaeus affinis 0-100%, Penaeus semisulacatus 0-1.87 %, Caridina babaulti basrensis 0-93.33 %, Atyaephyra desmaresti mesopotamica 0-100 %, Exopalaemon styliferus 0-27.27% ,Palaemon elegans 0- 26.66 % , Macrobrachium nipponense 0-73.33 %.&#x0D; . The results of the statistical analysis showed a positive relationship between abundance and water temperature, pH and salinity and showed significant differences between abundance and acuityP&lt; 0.007 between sovereignty and mean P&lt; 0.018 The correlation coefficient was positive between abundance and (temperature water, pH , Salinity and acacia) and the correlation coefficient between abundance and dissolved oxygen.

Effects of different times of probiotic additions on floc abundance and growth of white leg shrimp (Litopenaeus vannamei): Laboratory scale cultivation

Water quality management for aquaculture is very important because water is a living medium for aquaculture organisms. One of the technological products that use microbes to create a better environment by breaking down organic matter is probiotics. This study aims to determine the effects of different probiotic administration times on water quality in white leg shrimp culture at a laboratory scale. Juveniles of white leg shrimp with PL27 size were reared for 45 days and given four treatments with probiotics at different times. The result showed that the administration of probiotics with a short period interval had a significant effect on floc volume, absolute growth, survival rate, concentrations of ammonia, nitrate, and nitrite. Provision of probiotics with a short time span tended to reduce the concentration of ammonia, nitrate and nitrite. The difference in time of giving probiotics to bio-floc media increased the growth of white leg shrimp, improved water quality, and reduced the concentration of ammonia (NH3), nitrate (NO3), and nitrite (NO2).

Evaluation of caridean ecological distribution in the Ubatuba region, southeastern Brazilian coast using unsupervised machine learning technique

AbstractWe used the unsupervised machine learning technique to evaluate the environmental factors responsible for modulating the spatial and seasonal distribution of caridean shrimps from a southeastern region of the Brazilian coast. Samplings were collected from seven transects with an artisanal shrimp fishery boat with two double‐rig nets. Samplings occurred every month from October 2008 to September 2009. The most frequently captured species were Exhippolysmata oplophoroides, Leander paulensis, and Nematopalaemon schmitti. The highest abundance of shrimps occurred in autumn at the II, III, and V transects, which present a higher amount of coarse sediment and biodetritic fragments on the bottom. During autumn, the temperatures were the highest and salinity values were the lowest. Data evaluation indicated efficiency in the visualization of interactions of different shrimp species and environmental data. This kind of sediment may be allowing shrimps to burrow in shelters that prevent predation. The seasons with high temperatures and low salinities can offer better conditions for the establishment of the studied species, despite the fact that there is no hypothesis to prove it. Additionally, the higher abundance of such shrimps coincides with vegetal debris deposition, which could serve as food and provide protection for these shrimps. In this region, the vegetation matter deposited at the bottom of the bay comes from the Atlantic Forest. Overall, the preservation of the coastal forest strongly influences the abundance of this taxon, as it provides protection and food for these shrimps.

Bio ecology of the white shrimp Litopenaeus schmitti in Babitonga Bay. Do the current regulation of closed seasons is suitable to the lifecycle of this species?

The white shrimp Litopenaeus schimitti is the main way of living for artisanal fishermen who use the gerival for their capture in one of the main estuaries off south Brazil: Babitonga Bay. The abundance of the species is regulated by closed fishing seasons to protect spawning and recruitment, which may not in accordance with species’ life cycle. The present study evaluated the size structure, maturation, and abundance of white shrimp, to verify the effectiveness of these measures for the region. The highest abundances of the L. schmitti occurred between February and May, both in the inner bay and the adjacent marine area. Spawning occurred in the marine environment around 15 m depth, mainly in October and November, with the subsequent entry of post-larvae into the estuary around December, being available for artisanal fishing in January in the inner bay area. In February and March, juveniles migrated to the adjacent marine area, defining the main recruitment peak. Some lagging shrimp remained within the bay until September and October, with a complete disappearance in December. The first size of maturation for the white shrimp females was estimated at 15.16 cm. The results hereby obtained showed that the current closed season partially protects white shrimp spawning and recruitment in Babitonga Bay and the adjacent marine area suggesting that fishing restrictions during the months of February and March may benefit juvenile specimen’s migration from the estuary, however, the protection of the spawning females in October/November could also be taken into account as a way of maintaining stocks of white shrimp in the region.

Penaeid Shrimp in Chesapeake Bay: Population Growth and Black Gill Disease Syndrome

AbstractSince 1991, the number of penaeid shrimp occurring in Virginia waters of Chesapeake Bay has steadily increased, prompting an interest in developing a fishery. Although development of a shrimp fishery in the Chesapeake Bay region could bring economic benefits, the fishery may be hampered by the presence of a disease syndrome known as shrimp black gill (sBG). The objectives of our study were to (1) describe the spatial distribution and abundance patterns of shrimp in Chesapeake Bay, (2) relate relative abundance of shrimp to habitat characteristics, and (3) determine the presence and seasonality of sBG to better understand disease dynamics in the region. Subadult penaeid shrimp were collected monthly from Virginia waters by trawl from 1991 to 2017, and individuals were identified to species and counted. White shrimp Litopenaeus setiferus were the most numerous species captured, followed by brown shrimp Farfantepenaeus aztecus and pink shrimp F. duorarum. Shrimp were captured primarily from July to December. White shrimp were the only species that exhibited visible signs of sBG, which was first observed in October 2016 (13.4% prevalence); the condition continued into November and recurred the following year. Shrimp with visible signs of gill disease were examined by microscopy, histology, and PCR assay and were diagnosed with infections of a histophagous apostome ciliate, presumably Hyalophysa lynni. Any impacts of sBG on shrimp survival or marketability should be considered in fishery management plans to ensure sustainability of the resource.

Climate Indices Predict Black Gill Prevalence in White Shrimp Penaeus setiferus (Linnaeus, 1767) in South Carolina and Georgia, USA

The white shrimp fisheries in South Carolina and Georgia, USA, have undergone substantial reductions in commercial landings over the past few decades. These declines are associated with reduced commercial effort, shifting climate patterns, and disease outbreaks. For example, recent increases in the occurrence of gill melanization, also known as black gill, have led to the suggestion that this epidemic is a major contributor to reduced shrimp abundance in the region. The goal of this study was to assess long-term patterns and drivers of black gill, and its effects on white shrimp abundance, particularly during the fall, when most of the commercial harvest of white shrimp in this region has historically occurred. Data were compiled for fishery-independent (2002–2017) metrics of white shrimp abundance and black gill prevalence from seven estuaries along the South Carolina and Georgia coasts. Phenology of black gill was variable among years, but mean black gill prevalence was significantly related to the Pacific Decadal Oscillation and El Niño–Southern Oscillation climate indices. These analyses show that the prevalence of black gill is sensitive to large-scale fluctuations in climate patterns.

A seasonal dynamics and population status of the steno-endemic karst fairy shrimp Chirocephalus croaticus (Steuer, 1899) (Branchiopoda, Anostraca) from Slovenia

Abstract We investigated the presence and ecology of Chirocephalus croaticus (Steuer, 1899) during three successive seasons (spring and autumn 2018, spring 2019) at Lake Petelinje (SW Slovenia). Although the presence (duration, abundance) of this fairy shrimp strongly differs among different seasons and both years, we showed that in a season with favourable conditions (spring 2018) its abundance increases rapidly at the end of the season as the shrimps persist in small pools until the water dries out. The species may appear again during the autumn, however, its abundance and persistence seem to be much lower and shorter than during the spring, respectively. Nevertheless, persistence and abundance may also differ strongly among the two successive spring seasons (less shrimps found during the shorter season of 2019 than in 2018). Larvae appear first, and are most abundant at the beginning of the season, and are followed by adult males (protandry) and females, which become most abundant at the end of the season. Also, larvae seem to be more abundant on exposed bottom (gravel path), while adults are much more abundant in the shelter of a submerged meadow. Ovigerous females had 9-37 cysts (fertilized eggs) in their brood pouch, and the position of differently developed eggs changed during the season; the presence of females without eggs during mid- and at the end of season indicates the production of thin-shelled summer, and thick-shelled winter cysts, respectively. In contrast with the water decrease that is in strongly negative association with the abundance of the fairy shrimps (lake size — abundance: , ), no other environmental parameters were highly associated () with species abundance. Although the local population (one of only two currently known) seems to be in good condition, appropriate conservation action should be taken to prevent the decrease of this population in the future.

Environmental Drivers of Seagrass-Associated Nekton Abundance Across the Northern Gulf of Mexico

Small variations in environmental parameters can substantially alter species composition, but the extent to which different species respond to these changes remains obscure. A synoptic survey of seagrass-associated faunal communities was performed across the Gulf of Mexico using otter trawls coupled with seagrass and water quality assessments. The abundance of eight central seagrass inhabitants, representing a range of functional groups, were quantified to identify factors that best predicted their prevalence across environmental gradients and the consistency of these ecological relationships. Seagrass density and drift algal biomass generally had the strongest influence on animal abundance (40–67%), although relationships with drift algae were species specific and seemingly related to faunal size and mobility. Abundances of free-swimming pinfish, pigfish, and silver perch were negatively related to drift algae biomass (0.7, 0.7, and 1.0% Δ per 1 g·m−2 drift algae, respectively), whereas the abundance of pipefish (Syngnathus spp.) and brown/pink shrimp (Penaeus spp.) tended to be positively related to algal biomass (0.8 and 1.6% Δ per 1 g·m−2 drift algae). Shrimp abundances increased by 3.6% per 1% increase in light attenuation while the abundance of a higher-order visual predator, silver perch, negatively responded to light attenuation (1.1% Δ per 1% Δ vertical light attenuation). Additionally, bivariate plots of organismal abundance and salinity or canopy height indicated a unimodal relationship with peaks in abundance associated with intermediate values for several species. This study explored the extent species and functional groups responded to variation in key elements of the abiotic and biotic environment, providing insight into community development and offering resource managers quantitative targets for aspects of habitat quality.

Seasonal variation in the abundance and species diversity of penaeid shrimps from the coastal area of Sonmiani Bay Lagoon, Balochistan, Pakistan

Shrimp communities of the coastal habitat of the Sonmiani Lagoon were shown to be dominated by family Penaeidae. Seasonal variation in the relative abundance and species diversity of penaeid shrimps was derived from sampling of 2554 individuals representing twelve species of three genera. The results showed that species of the genus Penaeus dominated over those of the other two genera of penaeid shrimps i.e . Metapenaeus and Parapenaeopsis. The most abundant species of penaeid shrimps were Penaeus indicus (67.50 %), Metapenaeus affinis (13.31 %), Penaeus merguiensis (12.02 %), Metapenaeus brevicornis (4.26 %) and Metapenaeus stebbingi (1.60 %), respectively. Relative abundance varied seasonally within the species and between the seasons. Highest species richness in the lagoon was observed in the period of SW monsoon and the lowest in pre-monsoon season, whereas Diversity (H') was found to be highest in post-monsoon, and appeared to be influenced by the equitability ( J ) of distribution of individuals among the species. Temperature, salinity and pH influenced both the abundance and the diversity of shrimp fauna in the lagoon.

Diets of Staging Phalaropes at Great Salt Lake, Utah

ABSTRACTGreat Salt Lake, Utah, USA, is a critical staging area for Wilson's (Phalaropus tricolor) and red‐necked (Phalaropus lobatus) phalaropes. Both phalarope species depend upon abundant invertebrate prey in Great Salt Lake to fuel fall migrations, but the lake currently faces the threat of becoming increasingly saline due to water diversions and climate change. The lake changes may decrease the ability of Great Salt Lake to support the large populations of phalaropes that currently depend upon it. Assessing how a smaller and more saline Great Salt Lake will affect phalaropes is difficult without knowing what phalaropes are consuming during staging. We collected phalaropes from 4 different Great Salt Lake bays from 2012 through 2015 and identified prey items in their upper digestive tracts. We measured wet weights of different food items and examined total mass of food consumed by weighing gizzard contents. Phalarope diets differed across time and bays, and between phalarope species. Red‐necked phalaropes primarily consumed corixids (Corixidae) and brine fly (Ephydra hians, Ephydra cinerea) larva, pupa, and adults, whereas Wilson's phalaropes consumed brine flies, chironomids (Chironomidae) and Daphnia (Daphnia magna). Despite the abundance of brine shrimp (Artemia franciscana) in Great Salt Lake, both phalarope species rarely consumed them. Our results documented that phalaropes of Great Salt Lake are dependent for food in the less‐saline Farmington Bay and on brine flies produced in the hypersaline bays. Such information is critical for wildlife managers who are tasked with ensuring that Great Salt Lake will continue to support the large phalarope populations that depend on the lake's resources. © 2021 The Wildlife Society.

Which environmental factors are most relevant to the distribution of Sicyonia dorsalis (Penaeoidea: Sicyoniidae) in an upwelling region?

Knowledge of the environmental factors in an upwelling region is extremely important to understand their relationship with influences in the spatiotemporal densities of penaeid shrimps. Spatial and temporal patterns of distribution of Sicyonia dorsalis were evaluated in relation to temperature, salinity, organic matter, and sediment type in a tropical region influenced by upwelling, using monthly data (2010 to 2011 and 2013 to 2014). The very fine sand was found in 5 m depth and silt and clay and the highest organic matter (mean 16.94%) contents were predominated in 15 m depth. The mean minimum bottom temperature and the maximum salinity were found in spring (18.5 oC and 39.25 psu, respectively). The total of 686 shrimps captured and a consistent pattern of high relative abundance of shrimp in winter and spring and scarcity in autumn was observed. Shrimp abundance was highest in sites at 15 m and positively associated with sediment. The predominance of individuals in finer substrates (silt and clay) was related to higher levels of organic matter content (a food source for shrimp). Temperature was negatively associated with abundance, which was prominent from 19 to 21 °C. Temperature and sediment type were the factors that most influenced the spatiotemporal differences in the density of the S. dorsalis in an area influenced by the upwelling phenomenon. The study highlights the importance of understanding the patterns and drivers to the distribution of shrimps in order to develop modelling species distribution along the coastal region.

Fishers\u2019 knowledge detects ecological decay\xa0in the Mediterranean Sea

The Northern Adriatic Sea (NAS) is one of the most overexploited marine ecosystems in Europe. Given the gaps in scientific knowledge regarding the NAS, this study sought Fishers’ Ecological Knowledge (FEK) to determine NAS’ historical baselines for conservation. By interviewing 53 fishers in three ports of northern Italy, estimates of the catch rates of four commercial demersal species were generated over a 60-year period, and perceptions of target and non-target species’ diversity and benthic diversity were analysed in three groups of fishers (i.e. novices, experienced and veterans). Results showed a significant decline in perceived abundance of sole (Solea solea), common cuttlefish (Sepia officinalis) and mantis shrimp (Squilla mantis), and evidence was found of a Shifting Baseline Syndrome (SBS) among novices. Given FEK’s ability to complement scientific knowledge, fishers’ participation in marine management policies and intergenerational communication should be enhanced, to improve the status of marine ecosystems and hinder SBS.