Diet of Juvenile Alabama Shad (Alosa alabamae) in Two Northern Gulf of Mexico Drainages

Understanding food-web ecology is valuable to conservation by linking interactions of multiple species together and illustrating the functionality of trophic exchange. Alosa alabamae (Alabama Shad), an anadromous species, reproduces in northern Gulf of Mexico drainages from February through May, and for this study, the Pascagoula and Apalachicola rivers were chosen to sample juvenile Alabama Shad. The age-0 fish mature within these rivers and have the potential to impact the food web of the systems in which maturation occurs. The focus was to determine if diet changes as Alabama Shad mature, and to identify diet differences between drainages. Diets of Alabama Shad (SL) consisted primarily of a dark, almost black material labeled as unidentifiable organics. while larger Alabama Shad. \u3e50 mm SL, fed almost exclusively on insects. Many groups of aquatic and terrestrial insects were found in the stomachs of this species. Alabama Shad diets also differed among drainages, with the Apalachicola River being dominated by terrestrial insects, and the Pascagoula River having both terrestrial and aquatic insects. Diet and trophic placement of Alabama Shad may allow managers to understand the importance of this fish within its natal rivers

Environmental Conditions of 2 River Drainages Into the Northern Gulf of Mexico During Successful Hatching of Alabama Shad (\u3ci\u3eAlosa alabamae\u3c/i\u3e)

In recent years, the Alabama shad (Alosa alabamae) has experienced dramatic declines and extirpations from portions of its native range. Habitat degradation and barriers to migration are considered contributing factors to contraction in the distributional range this species. To identify conditions during successful spawning, river temperatures and discharges in 2 drainages of the northern Gulf of Mexico (the Apalachicola and Pascagoula rivers) were characterized during successful hatching “windows.” Sampling during 2005–2009 yielded 400 juvenile Alabama shad of which 261 were aged from counts of rings on sagittal otoliths. Results from logistic regression revealed that successful spawning coincided with increases in temperature within a specific range (9.4–21.5°C) and with an average drainage-dependent discharge volume (625.6 m³/s in the Apalachicola River and \u3e400.7 m³/s in the Pascagoula River). Timing of successful hatching windows differed between drainages but not between years within each drainage. Documenting and identifying the river conditions during successful reproduction provide important information on how to manage rivers to aid in the recovery of this species of conservation concern

First Record of \u3ci\u3eAgonostomus monticola\u3c/i\u3e (Family: Mugilidae) in Mississippi Freshwaters with Notes of its Distribution in the Southern United States

An individual of Agonostomus monticola (Mountain Mullet) was collected in southern Mississippi while conducting a series of community surveys on 7 November 2007. This is the first documented report of Mountain Mullet in Mississippi freshwaters, even though there are reports of three specimens collected in Mississippi estuarine waters in 1937. Given its life history and difficulties in sampling, it is likely that Mountain Mullet has a broader distribution and more frequently occurs in Gulf Coast drainages in the southern US than was previously thought

Lipoxin A4 Stimulates Calcium-Activated Chloride Currents and Increases Airway Surface Liquid Height in Normal and Cystic Fibrosis Airway Epithelia

Cystic Fibrosis (CF) is a genetic disease characterised by a deficit in epithelial Cl− secretion which in the lung leads to airway dehydration and a reduced Airway Surface Liquid (ASL) height. The endogenous lipoxin LXA4 is a member of the newly identified eicosanoids playing a key role in ending the inflammatory process. Levels of LXA4 are reported to be decreased in the airways of patients with CF. We have previously shown that in normal human bronchial epithelial cells, LXA4 produced a rapid and transient increase in intracellular Ca2+. We have investigated, the effect of LXA4 on Cl− secretion and the functional consequences on ASL generation in bronchial epithelial cells obtained from CF and non-CF patient biopsies and in bronchial epithelial cell lines. We found that LXA4 stimulated a rapid intracellular Ca2+ increase in all of the different CF bronchial epithelial cells tested. In non-CF and CF bronchial epithelia, LXA4 stimulated whole-cell Cl− currents which were inhibited by NPPB (calcium-activated Cl− channel inhibitor), BAPTA-AM (chelator of intracellular Ca2+) but not by CFTRinh-172 (CFTR inhibitor). We found, using confocal imaging, that LXA4 increased the ASL height in non-CF and in CF airway bronchial epithelia. The LXA4 effect on ASL height was sensitive to bumetanide, an inhibitor of transepithelial Cl− secretion. The LXA4 stimulation of intracellular Ca2+, whole-cell Cl− currents, conductances and ASL height were inhibited by Boc-2, a specific antagonist of the ALX/FPR2 receptor. Our results provide, for the first time, evidence for a novel role of LXA4 in the stimulation of intracellular Ca2+ signalling leading to Ca2+-activated Cl− secretion and enhanced ASL height in non-CF and CF bronchial epithelia

Habitat Use of Age 0 Alabama Shad in the Pascagoula River Drainage, USA

Alabama shad (Alosa alabamae) is an anadromous species that spawns in Gulf of Mexico drainages and is a NOAA Fisheries Species of Concern. Habitat degradation and barriers to migration are considered contributing factors to range contraction that has left just the Pascagoula River drainage population in Mississippi. We studied juvenile life history and autecology in three rivers within the drainage. We collected fish, habitat and physicochemical data in three habitat types (sandbar, open channel and bank) from June to October 2004–2006. Sandbar habitat was favoured by smaller individuals early in the year. Catch per unit effort (CPUE) decreased through the summer as larger fish began occupying bank and open channel habitat. The most parsimonious model of abundance included year and river variables, while patterns of presence and absence were best explained by river, habitat type and physiochemical variables. While all three rivers in the drainage contained Alabama shad, fish were less abundant and had lower condition values in the Chickasawhay River. Earlier work suggested the Alabama shad may gradually move downstream towards the Gulf of Mexico in their first year. However, we found no evidence of this and captured large fish high in the drainage late in the year

Morphometric Comparisons of the Gulf sturgeon (\u3ci\u3eAcipenser oxyrinchus desotoi\u3c/i\u3e Mitchill, 1815) In Western and Eastern Population Extremes

The Gulf sturgeon, Acipenser oxyrinchus desotoi Mitchill 1815, is an anadromous fish native to the Gulf of Mexico (GOM). This threatened species ascend northern GOM rivers ranging from the Pearl River, Louisiana to the Suwannee River, Florida. The drainage fidelity seen within this species coupled with the complex migration patterns create many unknowns concerning the functionality between drainages and size classes. Being a threatened species that cannot be sacrificed, morphometric measurements are difficult to acquire due to minimized handling times and non-lethal data collection methods. Seven morphometric measurements of Gulf sturgeon were compared between western and eastern GOM rivers and multiple size classes (juvenile, sub-adult, and adult). Principal Component, Discriminant Function, and Maximum Chance Criterion analyses were conducted and identified differentiating morphometrics and classified groupings among size classes and rivers of Gulf sturgeon. This morphometric approach has the potential to be used in parallel with molecular findings and should allow managers to identify sub-populations for a variety of threatened and endangered species

Phylogenetic Relationships Among North American \u3ci\u3eAlosa\u3c/i\u3e Species (Clupeidae)

A phylogeny of the six North American species in the genus Alosa, with representatives of three Eurasian species, was generated using mtDNA sequences. This was accomplished by obtaining sequences for three North American species and additional geographical sampling of the other three species. The subgenus Alosa, including the formerly recognized subgenus Caspialosa, formed a strongly supported monophyletic group. Alosa alabamae was part of a polytomy with Alosa sapidissima, which was interpreted to support the recognition of A. alabamae as an incipient, yet distinct, species. The subgenus Pomolobus was not recovered as a monophyletic group. Alosa chrysochloris was basal to all other Alosa, although this position was only weakly supported. Previous work had indicated that Alosa pseudoharengus and Alosa aestivalis are not reciprocally monophyletic, but additional sampling in this study did not detect any further cases of shared haplotypes between the two species. The phylogeny supports previous hypotheses that the evolution of North American Alosa species in the Gulf of Mexico (A. chrysochloris and A. alabamae) was the result of two independent events. First, the ancestor of A. chrysochloris was isolated in the Gulf of Mexico, likely by the close of the Suwannee Straits, and this was followed later by dispersal of the ancestor of A. alabamae around the Florida peninsula into the Gulf of Mexico sometime during or after the Pleistocene

Patterns of Co-Existence and Hybridisation between Narrowly Endemic (Fundulus Euryzonus) and Broadly Distributed (F. Olivaceus) Topminnows in a Riverine Contact Zone

Two ecologically similar topminnow species (Fundulus olivaceus and F. euryzonus) were studied in a contact zone in the West Fork of the Amite River of the Lake Pontchartrain drainage. We assessed whether relative abundance and measures of fitness of each species, and their hybrids, were correlated with predictable abiotic or biotic factors. We sampled the full fish assemblage and measured a suite of local and landscape level environmental characteristics at ten sites. Topminnows were genotyped to identify individuals of hybrid ancestry. We compared the abundance and distribution of parental species in the context of overall fish assemblage structure and environmental variables. Hybridisation was generally rare with only nine of 244 genotyped topminnows exhibiting evidence of hybrid ancestry. The relative abundance of the two topminnows was related to site assemblage structure, species diversity and a number of local but not landscape level environmental variables. Both species were in better condition and females were more fecund at sites with greater abundance of F. olivaceus. Hybrid individuals were not morphological or ecological intermediates

Consistent SpatioTemporal Estuarine Habitat Use during Emigration or Immigration of a Western Population of Gulf Sturgeon

<p>The spatial and seasonal occupancy by Gulf Sturgeon <i>Acipenser oxyrinchus desotoi</i> was estimated using acoustically tagged fish in the Pascagoula River estuary over a 3-year period (2010–2013) and was based on 131,381 detections. Juveniles spent considerably more time in the estuary than subadults or adults, but that varied by year. Gulf Sturgeon of all size-classes entered the acoustic array earlier when stream discharge was high (2011, 2012) compared with when it was lower (2010). The difference was about 14–28 d earlier for adults and subadults but only 12–17 d for juveniles. Temporally, there were no significant differences in occupancy by year or season for adults or subadults or by year for juvenile Gulf Sturgeon, suggesting repeated patterns across the 3 years of this study. Significant and consistent spatial differences in occupancy occurred by array zone, with juveniles occupying the West zone more than the East and River zones of the acoustic array; however, occupancy in the River zone was greater than in the East zone. We found similar patterns for subadults, with the highest occupancy in the West zone compared with the East zone; use was higher in the River zone than in the East zone but there was no difference between the River and West zones. In contrast, no year, season, or zone patterns were identified for adult Gulf Sturgeon, suggesting annual movement along a defined travel corridor (from the River zone to the West zone to offshore islands), with little time spent in the estuary. Adults appear to move quickly through the system during emigration (fall) and immigration (spring) compared with longer but more variable occupancy for juveniles and subadults. Our long-term data illustrates the importance of habitat connectivity in the recovery of Gulf Sturgeon and enhances earlier work on estuarine zones used during migration periods and estuarine residency; both are important for a better understanding of critical habitat maintenance and the development of a robust recovery plan.</p> <p>Received May 6, 2015; accepted September 2, 2015</p

Effects of Annual Droughts on Fish Communities in Mississippi Sound Estuaries

© 2018, Coastal and Estuarine Research Federation. The Mississippi coastal region has two major rivers and four smaller rivers influencing the estuaries that make up the Mississippi Sound. The islands off Mississippi create a barrier which allows the area to be a widespread, productive estuarine region. With such a dependence on discharge from the drainages, it is important to understand the effect of salinity regimes on fish communities. Drought conditions in other regions have been shown to dramatically change the fish community structure. We used the long running Interjurisdictional Fisheries Program database (2006–2014) within Mississippi state waters and compared yearly fish communities between drought and non-drought years. Non-metric Multidimensional Scaling (nMDS), Analysis of Similarity (ANOSIM), and Indicator Species Analysis (ISA) were used to compare drought and non-drought conditions in the Mississippi Sound. During 2006 and 2007, which were identified as drought years by the Palmer Drought Severity Index (PDSI), differences in fish community structure were identified and compared to non-drought years (2008–2009 and 2011–2014). The ISA identified a total of eight species that were significantly influenced by drought years. Of the eight species, the abundance of seven species significantly decreased while the abundance of one species significantly increased. With an increasing human population in central and south Mississippi, pressure on freshwater resources is likely to increase, resulting in possible changes in the fish community dynamics of the Mississippi Sound. Understanding the influence of decreased river discharges will assist managers in determining the impacts of freshwater withdrawals during base flow periods