Influence of temperature on the occurrence and distribution of the sand shrimp Crangon septemspinosaSay, 1818 (Decapoda: Caridea: Crangonidae) in polyhaline lagoons in Maryland, USA

Abstract Sand shrimp, Crangon septemspinosaSay, 1818, is one of the most abundant decapod crustaceans in estuaries and coastal waters of the northwestern Atlantic Ocean, though little is known about its population dynamics in polyhaline lagoons of the mid-Atlantic region. Seasonal and spatial patterns of abundance and distribution of C. septemspinosa were evaluated in relation to temperature, salinity, and dissolved oxygen in Maryland coastal bays (MCBs) using monthly data (April to October 1994 to 2012). We tested the hypothesis that temperature influences the occurrence and distribution of sand shrimp in the lagoons. A consistent pattern of high relative abundance of shrimp in spring and its scarcity in summer and early fall was observed. Shrimp abundance was highest in the northern bays and at sites closest to the Ocean City Inlet during April, but lowest at sites in the upper parts of Chincoteague Bay and MCBs tributaries. As mean temperature increased from April (12.2–17.1 oC) to June (21.8–26.7 oC), the relative abundance of the shrimp decreased substantially at most sites except at two sites where mean water temperature was comparatively low (21.8–23.3 oC). By July, when mean temperature was at its maximum (23.1–28.9 oC) in the bays, shrimp were rarely caught in trawls even in early fall in spite of the decline in temperature. It is likely that shrimp moved into nearshore waters with cooler temperature or suffered high mortality due to high temperature during this period. Generalized linear models suggest that temperature, and temperature and dissolved oxygen combined, were the most important abiotic factors examined that influenced the spatial distribution of C. septemspinosa in May and June, respectively. Considering their trophic importance, the spatio-temporal variations in the occurrence and abundance of the shrimp have implications for food web dynamics in the MCBs.

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Variations inter-populations de la structure d'âge et de la croissance du Prosobranche Bithynia tentaculata L.

Canadian Journal of Zoology ◽

10.1139/z85-202 ◽

1985 ◽

Vol 63 (6) ◽

pp. 1345-1353 ◽

Cited By ~ 2

Author(s):

B. Vincent ◽

C. Létourneau

Keyword(s):

Age Structure ◽

Sexual Maturity ◽

Abiotic Factors ◽

Temporal Variations ◽

Population Densities ◽

Bithynia Tentaculata ◽

Spatio Temporal ◽

Sudden Decrease ◽

Velocity Water ◽

St Lawrence River

The main variations in age structure and growth of different generations were studied in 25 populations of the prosobranch Bithynia tentaculata in the St. Lawrence River (Québec). The general unbalanced age structures of the populations reflect a low recruitment encountered during an odd year because of a general disturbance in the environment. The age structure is correlated to temperature, sediments, and current velocity. Water chemistry is largely responsible for the spatial variations in lengths of the adults, but these variations do not seem to influence the age at sexual maturity. Population densities may be regulated by an increase in the growth rate of young which would reduce the age at sexual maturity in populations with low densities; this mechanism would, however, be of little use to compensate a sudden decrease in density or an unbalanced age structure in a population. These results and those of previous studies on this species reveal the important role played by abiotic factors in regulating the spatio-temporal variations of the demographic profile of this prosobranch which possesses a high phenotypic plasticity.[Journal translation]

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Spatio-temporal distribution patterns of Chironomidae communities in the wadis of Northern Tunisia

Brazilian Journal of Biology ◽

10.1590/1519-6984.247073 ◽

2022 ◽

Vol 82 ◽

Author(s):

S. Boulaaba ◽

S. Zrelli ◽

A. Hedfi ◽

M. Ben Ali ◽

M. Boumaiza ◽

...

Keyword(s):

Linear Models ◽

Environmental Gradients ◽

Abiotic Factors ◽

Temporal Distribution ◽

Thermal Conditions ◽

Sodium Concentration ◽

Dominant Group ◽

Water Conductivity ◽

Northern Tunisia ◽

Spatio Temporal

Abstract In Northern Tunisia, seasonal streams, called wadi, are characterized by extreme hydrological and thermal conditions. These freshwater systems have very particular features as a result of their strong irregularity of flow due to limited precipitation runoff regime, leading to strong seasonal hydrologic fluctuations. The current study focused on the spatio-temporal distribution of chironomids in 28 sampling sites spread across the Northern Tunisia. By emplying PERMANOVA, the results indicated a significant spatio-temporal variation along various environmental gradients. The main abiotic factors responsible for noted differences in the spatial distribution of chironomids in wadi were the conductivity and temperature, closely followed by altitude, pH, salinity, talweg slope and dissolved oxygen, identified as such by employing distance-based linear models’ procedure. The Distance-based redundancy analysis ordination showed two main groups: the first clustered the Bizerte sites, which were characterized by high water conductivity, sodium concentration and salinity. The second main group comprised sites from the Tell zone and was characterized by low temperatures, neutral pH, low conductivity and nutrients content. The subfamily TANYPODIINAE (e.g., Prochladius sp., Prochladius choerus (Meigen, 1804) and Macropelopia sp.) was the dominant group at Tell zone, whereas species such as Diamesa starmachi (Kownacki et Kownacha, 1970) and Potthastia gaedii (Meigen, 1838) were found only in Tell Wadis. In contrast, chironomid species such as Diamesa starmachi (Kownacki et Kownacha, 1970), Potthastia gaedii (Meigen, 1838), Procladius choreus (Meigen, 1804) were specific for Tell Mountain. Cap Bon wadis region was dominated by genus Cladotanytarsus sp. The results of this survey liked the taxonomic composition of chironomid assemblages to the variation of hydromorphological and physic-chemical gradients across the northern Tunisia wadis.

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The composition and heterogeneity of the rich and diverse rotifers (Rotifera: Eurotatoria) of the floodplain lakes (beels) of the Majuli River Island, Assam State (Northeast India)

Opuscula Zoologica ◽

10.18348/opzool.2021.2.165 ◽

2021 ◽

Vol 52 (2) ◽

pp. 165-181

Author(s):

Bhushan Kumar Sharma ◽

Sumita Sharma

Keyword(s):

Abiotic Factors ◽

Regional Distribution ◽

Hard Water ◽

Temporal Variations ◽

Northeast India ◽

Floodplain Lakes ◽

Brahmaputra Basin ◽

Spatio Temporal ◽

The Rich ◽

The Tropics

The tropical and subtropical floodplain lakes are hypothesized as one of the globally interesting rotifer rich ecosystems. Our study indicating the biodiverse Rotifera of ten ‘slightly acidic to circum-neutral, moderately hard-water and de-mineralized’ tropical floodplain lakes (beels) of the Majuli River Island of the Brahmaputra river basin of northeast India mendorses this hypothesis. Total richness, the richness of important families and community similarities affirm heterogeneity mof the rotifer species composition amongst the beels. The species richness registers significant spatio-temporal variations with seasonal differences amongst the beels and individually in each beel, and lacks significant influence of the recorded abiotic factors. The constellations of 76-81 species in three beels during winter and 76 species in one beel during pre-monsoon are noteworthy instances of ‘Rotifera paradox’. The rotifer fauna of the Majuli beels registers affinity with Southeast Asian and Oriental faunas, records several species of the regional distribution interest and exhibits the littoral-periphytic nature, while application of Q B/T and Q L/B quotients depicts limitations. This study merits ecological diversity interest for Rotifera vis-avis the floodplain lakes of India and elsewhere from the tropics and subtropics, and assumes biodiversity conservation importance due to threat of extinction of the Majuli – an alluvial floodplain of the Brahmaputra basin.

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Spatio-temporal variations of nitrogen isotopic records in the Arabian Sea

Biogeosciences Discussions ◽

10.5194/bgd-11-8713-2014 ◽

2014 ◽

Vol 11 (6) ◽

pp. 8713-8748

Author(s):

S.-J. Kao ◽

B. Wang ◽

L. Zheng ◽

K. Selvaraj ◽

S.-C. Hsu ◽

...

Keyword(s):

Dissolved Oxygen ◽

Arabian Sea ◽

Euphotic Zone ◽

Temporal Variations ◽

Southeastern Part ◽

Global Pattern ◽

Spatio Temporal ◽

Isotopic Records ◽

Bottom Depth ◽

Reported Data

Abstract. Nitrogen and carbon contents vs. their isotopic compositions for past 35 ka for a sediment core (SK177/11) collected from the most southeastern part of the Arabian Sea (AS) were presented. A one-step increase in δ15Nbulk starting at the deglaciation with a corresponding decrease in δ13CTOC was found similar to documentation elsewhere which showed a global coherence in general. We synthesized available reports including dissolved oxygen, δ15N of nitrate (δ15NNO3), as well as δ15N of total nitrogen (δ15Nbulk) for trap material and surface/downcore sediments in the AS in order to explore the past nitrogen dynamics in the Arabian Sea. According to 25 μmol kg−1 dissolved oxygen isopleth at 150 m deep, we classified all reported data into northern and southern groups. We obtained geographically distinctive bottom-depth effects for northern and southern AS at different climate stages. By eliminating the bias caused by bottom depth, the modern day sedimentary δ15Nbulk values largely reflect the δ15NNO3 supply from the bottom of the euphotic zone; meanwhile, the diffusive sedimentary δ15Nbulk in long cores became confined revealing a more consistent pattern except recent 6 ka. The nitrogen cycle in entire AS apparently responded to open-ocean changes until 6 ka, during which further enhanced denitrification in the northern AS was likely local and driven by monsoon; while in the southern AS either nitrogen fixation was enhanced correspondingly to the continuously reduced δ15Nbulk for a compensation or the decreasing trend just followed the global pattern dominated by a longer term coupling of N2 fixation and denitrification.

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