Impacts of mariculture practices on the temporal distribution of macrobenthos in Sandu Bay, South China

Sandu Bay is located in the East China Sea and is characterized by high-density fish farming and kelp culture. Despite this, little is known about the impacts of these different mariculture practices on the local environment. We investigated the temporal variation in macrobenthos and environmental conditions at three sites in the bay （fish farming site, kelp culture site, and a control site）. We collected water and sediment samples during nine cruises between May 2009 and February 2010. The density of macrobenthos peaked at the fish farming site in July （655 ind./mE） whereas density did not fluctuate as widely at the other two sites. Biomass varied significantly at both the control and kelp culture sites, but had only a single peak at the fish farming site in June （21.90 g/mE）. The dominant species varied throughout the study period at the control and kelp culture sites, whereas a single terebellid species （Lysilla pacifica） dominated the macrobenthos at the fish farming site. The diversity index H＇ increased at the control site beginning in February then decreased after May, whereas H＇ was low at the other sites in December. The mean dissolved oxygen level was highest at the control site （6.59 mg/L） and lowest at the fish farming site （5.54 mg/L）. DO levels were lowest at all sites in summer （July and August）. The sediment acid volatile sulfide content was higher at the fish farming site （1.46 mg/g dry weight） than those at the kelp culture and control sites （1.22 and 0.14 mg/g, respectively）. Our results suggest that mariculture practices have a clear impact on the benthic environment/ community in Sandu Bay.

Facies analysis and palaeoecology of the Jurassic Spiti Shale Formation in the Spiti area,Northern India

The Spiti Shale Formation is a widely distributed stratigraphic unit of the passive northern margin of the Indian craton,deposited between the Callovian and earliest Cretaceous.The siliciclastic strata are dominated by dark-grey to black argillaceous silt.As the formation has undergone intense tectonic stress involving folding and faulting,it is very difficult to document a complete section.In the type area,the Spiti Valley,six sections have been measured that document parts of the three informal members of the formation,the Lower,Middle,and Upper members.Despite its uniform appearance,eight facies/biofacies types could be distinguished,ranging from the anoxic shale facies,with ammonites and belemnites as the only faunal elements,to the dysoxic Malayomaorica and Bositra biofacies,and the oxic to anoxic offshore shelf facies,which are characterized by low-diversity macrobenthos associations.Other facies are the condensed glauconiticphosphoritic mudrock facies and the Fe-oolitic siltstone facies(both characterized by sediment starvation),the aerated argillaceous silt-sandstone facies,and the tide-influenced nearshore shelf facies.The benthic macrofauna represents four bivalve-dominated associations all characterized by a very low to low species diversity.They are the Bositra buchii,the Australobuchia spitiensis,the Palaeonucula cuneiformis-Pruvostiella hermanni-Indogrammatodon egertonianus,and the Malayomaorica sp.-Australobuchia spitiensis-Retroceramus haasti association.Sediments and macrobenthic associations indicate that the Spiti Shale Formation represents outer to inner shelf environments,which for much of the time were subjected to upwelling and anoxic to dysoxic conditions.Distinct shallowing at the top characterizes the transition to the overlying Lower Cretaceous Giumal Formation.