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Assessment of water quality and its effect on prawn abundance in three tributaries of Shiwalik rivers: Chenab and Ravi of Jammu, India?a case study
No full textThe freshwater rivers from Shiwalik Himalayas have abundant prawn resources of high economic value and play a major
role in the livelihood of local fishermen. The present study aimed to determine the variation in prawn abundance explained
by changes in water quality among three different streams (Gho Manhasa stream, Chadwal stream and Nagri stream). The
highest abundance of prawns was found in the Gho Manhasa during the premonsoon season and lowest in the Chadwal stream
during the monsoon season. Chadwal stream witnessed maximum anthropogenic activities resulting in the decline of the water
quality affecting prawn fauna. Cluster analysis based on similarity in terms of prawn abundance revealed that the Chadwal
stream is different from the other two streams whereas non-metric multidimensional scaling plot based on species abundance
corresponding to different seasons and physiochemical parameters showed the water quality of the monsoon season of the
Chadwal stream to be extremely different. Principal component analysis showed clear separation across various sites and
seasons based on physicochemical parameters. Karl Pearson correlation coefficient and canonical correspondence analysis
indicated that the turbidity, total dissolved solids, nitrate, chloride, calcium, magnesium and dissolved oxygen are significant
parameters influencing the abundance of prawns. The population of Macrobrachium dayanum and Macrobrachium kistnense
was very less in the Chadwal stream owing to unfavorable physicochemical parameters. Therefore, conservation measures
are suggested which should be immediately implemented before the streams witness a further decline in their populations
Free-swimming fauna associated with influxes of pelagic sargassum: Implications for management and harvesting
No full textMass accumulations of pelagic sargassum (Sargassum natans and S. fluitans) in
the Tropical Atlantic, across the Caribbean and off the coast of West Africa, are
causing extensive ecological and socioeconomic harm. The extraordinary
volumes of sargassum influxes could also provide a business opportunity if
innovative ways are developed to utilise the raw material. In-water harvesting
provides the best opportunity to collect substantial amounts of ?fresh? sargassum
that can be used in a variety of applications. However, sargassum rafts are living
and diverse ecosystems with a range of associated fauna including fish that are
targeted by fishers. The consequences of in-water harvesting of sargassum on
the biodiversity, including associated fishes, remain poorly understood.
Characterisation of this biodiversity within nearshore and offshore
environments is needed to help guide best harvest practices and assess
possible impacts on fishing opportunities. We assessed the free-swimming
fauna associated with sargassum rafts at various distances from shore with the
use of underwater video recordings. Over a three-month period, a total of 35
underwater surveys were conducted off the eastern and southern coastline of
Barbados. Thirteen species (12 fishes and one comb jelly) from 8 families were
identified, with the family Carangidae representing the greatest number of
species (n=6). Application of the MaxN metric (maximum number of
individuals of a species seen during deployment) revealed significant
correlations with raft characteristics notably raft volume, raft distance from
shore and water depth. The three environmental variables accounted for 9% of
the variation (adjusted R2) in the free-swimming community composition with
raft volume being the major driver of species richness. This aligns with ecological
theory and supports our hypothesis that larger rafts would host greater species
richness. The results demonstrate a strong affiliation between pelagic sargassum
rafts and species biodiversity and abundance that will need to be considered by
managers when seeking a best compromise between protecting beaches from
inundation by sargassum and protecting biodiversity and fishing opportunities
Assessing larval fish diversity and conservation needs in the Luzon strait using DNA barcoding
No full textAccurate species identification and biodiversity assessment of
larval fish are essential for effective management and conservation of fisheries
resources, as it allows for the estimation of parent stocks, assessment of future
recruitment, and prediction of spawning and nursing grounds. However,
traditional morphology-based identification methods have inherent limitations,
highlighting the need for accurate and efficient techniques to address these
challenges effectively
Assessing larval fish diversity and conservation needs in the Luzon strait using DNA barcoding
No full textAccurate species identification and biodiversity assessment of
larval fish are essential for effective management and conservation of fisheries
resources, as it allows for the estimation of parent stocks, assessment of future
recruitment, and prediction of spawning and nursing grounds. However,
traditional morphology-based identification methods have inherent limitations,
highlighting the need for accurate and efficient techniques to address these
challenges effectively
ANALISIS EKO-BIOLOGI SEBAGAI ASAS PENGURUSAN SUMBER KERANGAN VENUS BERALUN (Paratapes undulatus) DI SIDOARJO, INDONESIA
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