Fine-scale spatial and temporal acoustic occurrence of island-associated odontocetes near a mid-oceanic atoll in the northern Indian Ocean

© The Author(s), 2022. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Panicker, D., Baumgartner, M. F., & Stafford, K. M. Fine-scale spatial and temporal acoustic occurrence of island-associated odontocetes near a mid-oceanic atoll in the northern Indian Ocean. Marine Ecology Progress Series, 683, (2022): 195–208, https://doi.org/10.3354/meps13947.Temporal patterns of oceanic predators can provide valuable information on both lunar and diel influences not just on the distributions of these predators, but also on prey patches that are often difficult to study. Mid-oceanic island chains in the northern Indian Ocean have high odontocete occurrence, but the ecology of these animals is not well characterized. We investigated fine-scale spatial and temporal patterns of island-associated odontocetes using passive acoustic monitoring from January 2019 to January 2020 around Kavaratti Island, Lakshadweep, India. Based on opportunistic recordings in the presence of odontocetes, the majority of the detected whistles were likely made by spinner dolphins Stenella longirostris. We identified a resident population whose whistle occurrence was significantly influenced by month, site, and diel and lunar cycles. More acoustic detections were made in the northeast monsoon month of November and fewer during pre-monsoon and southwest monsoon periods. Distinct day-night differences along with fine-scale temporal variability were also observed, suggesting that delphinids use nearshore waters as a daytime resting habitat. Odontocete detections were highest during the new moon period and lowest during the first quarter phase. Detection rates were higher on the south side of the island. Our study shows that solar and lunar cycles modulate odontocete vocal occurrence, presumably through influences on their prey. Similarities of odontocete occurrence around Lakshadweep to other mid-oceanic island chains suggests that an island-associated micronekton community may exist around Lakshadweep that may also be important to other pelagic species targeted by local fisheries.Funding was provided by the Office of Naval Research Marine Mammal Biology Program, USA, under grant N000141812795. We thank Ajith Kumar, the National Centre for Biological Sciences and Idrees Babu for in-country support

Isolation of acid soluble collagen from daggertooth pike conger (Muraenesox cinereus) and evaluation of its antimicrobial activity

The study was conducted to isolate acid soluble collagen (ASC) from daggertooth pike conger eel and to evaluate the antimicrobial activity of the isolated protein. Conger eels were collected from Kochi harbour. The proximate composition of eel skin consisted of 68.73 per cent of moisture on a wet basis with a crude protein, crude fat and total ash of 30.24 per cent, 12.17 per cent and 2.16 per cent respectively on a dry matter basis. Conger eel skin collagen was isolated by treating with 0.5 M acetic acid after pretreatment with 0.1 N NaOH and 10 per cent butanol. Salting out and precipitation of ASC was carried out by adding NaCl to a final concentration of 2.3 M. Precipitated ASC was then dialysed against 0.1 M acetic acid for 24h and then in distilled water until neutral pH was obtained. The yield of ASC was 12.78 per cent on a wet basis and 31.95 per cent on a dry basis. The antimicrobial activity of ASC was determined by the agar diffusion method. ASC showed antimicrobial activity against both E. coli and S. aureus

Analysis of differential expression of microRNA, bta-miR-93 in lipopolysaccharide challenged peripheral blood mononuclear cells of cattle

The present study was undertaken to analyse the differences in the microRNA (miRNA) expression in lipopolysaccharide (LPS) challenged and unchallenged peripheral blood mononuclear cells (PBMCs) of cattle. The research work was carried out in adult apparently healthy female crossbred cattle maintained at the University Livestock Farm and Fodder Research and Development Scheme, Mannuthy. The expression of miRNA and bta-miR-93 was profiled in the present study by qRT-PCR assay. In silico analysis was done using various online bioinformatic tools for the prediction of target genes, gene ontology analysis and also to study the cellular pathways associated to the target genes of bta-miR-93. The expression analysis of bta-miR- 93 showed decrease in its expression in LPS treated PBMCs when compared to control cells. Besides, significant enrichment of target genes of bta-miR-93 was noticed in many immune-related GO terms and in critical immune-associated cellular pathways. The findings of the current study will help in understanding the regulatory role of bta-miR-93 in LPS-mediated immune responses in cattle

Radiative Forcing of Black Carbon over Delhi

The radiative effects of black carbon (BC) aerosols over New Delhi, the capital city of India, for the period August 2010–July 2011, have been investigated using Santa Barbara DISTORT Atmospheric Radiative Transfer (SBDART) model in the present paper. The monthly mean BC concentrations in Delhi, an urban location, vary in between 15.935 ± 2.06 μg m−3 (December 2010)–2.44 ± 0.58 μg m−3 (July 2011). The highest value for monthly mean BC forcing has been found to be in November 2010 (66.10 ± 6.86 Wm−2) and the lowest in July 2011 (23 ± 3.89 Wm−2). Being the host city for the XIX Commonwealth Games (CWG-2010), government of Delhi set up a plan to reduce emissions of air pollutants during Games, from 03 October to 14 October, 2010. But opposite to the expectations, the emission controls implemented were not sufficient to reduce the pollutants like black carbon (BC), and therefore relatively a high value of BC radiative forcing (44.36 ± 2.4) was observed during the month of October 2010

Effect of differential heat treatments on antibacterial activity of fermented goat milk

The present study was conducted to evaluate the effect of three different temperatures on the antibacterial potential of fermented goat milk.Goat milk is one of the naturalfoods to complete perfection.Bioactive peptides, the specific protein fragments that have a positive impact on body functions, can be produced during milk fermentation. Thanks to the starter cultures’ proteolytic activity.Fresh pooled goat milk sample collected was divided into four lots. One set was used for raw milk analysis and the remaining three were subjected to heat treatment at three different timetemperature combinations namely;72°C for 15 sec, 85°C for 10 min, and 121° C for 15 min. These samples were cooled immediately to 42ºC, inoculated with 0.04 % DVS yogurt culture,incubated at 42º C for 4 hrs, and then stored at 5±2°C for 21 days for storage studies. The analysis was carried out at 7-day intervals. An agar well diffusion assay was performed to assess the inhibitory activity ofWater-soluble peptide extracts (WSPE) of these samples against Bacillus cereus ATCC 10876, Escherichia coli NCIM 2685, Salmonella enterica ATCC 6017, and Staphylococcus aureus ATCC 25923. The milk that was heated to 85°C for 10 min before fermentation showed the highest antibacterial activity against E.coli during the 7th and 14th day of storage, withthe zone of inhibition measuredat 17±0.433mm and 21±0.55mm respectively.Thus, it can be concluded that milk heated at 85°C for 10 min had better antibacterial activity than the other two treatments

Understanding cetacean community composition and distribution in Lakshadweep waters, Northern Indian Ocean

Thesis (Ph.D.)--University of Washington, 2022The Northern Indian Ocean (NIO) is a region of high environment variability driven by seasonally reversing winds. The southwest monsoons generate substantial plankton blooms in these tropical waters and shape biogeography of higher trophic levels. Cetaceans in oceanic waters are good indicators of epipelagic and mesopelagic prey bases. This dissertation examines species composition and distribution of cetaceans in a mid-oceanic island habitat in southeastern Arabian Sea. I use passive acoustic monitoring (PAM), which is particularly useful to collect data year-round including night periods and the rough-weather southwest monsoon season when visual surveys are challenging. In Chapter 2, I examine the occurrence and species composition of the cetacean community in the Lakshadweep archipelago via visual surveys using a platform of opportunity. The surveys documented 139 sightings, including eight odontocete species and one mysticete species. Occurrence of cetacean species differed across seafloor slope gradients and distances to nearest landmass. In Chapter 3, I investigate baleen whale occurrence in Lakshadweep waters using PAM. The study showed occurrence of Central Indian Ocean (CIO; formerly Northern Indian Ocean) acoustic population of blue whales in Indian waters. These results extend the known range of CIO pygmy blue whales about 1000 km north-westward from the waters surrounding Sri Lanka. In Chapter 4, I determined the occurrence and temporal patterns of island-associated odontocetes in Lakshadweep waters using PAM. A resident population, likely to be spinner dolphins, was identified. Whistle occurrence was significantly influenced by month, site, and diel and lunar cycles. Similarities of odontocete occurrence to other mid-oceanic island chains suggest that an island-associated micronekton community may exist around Lakshadweep. In Chapter 5, I characterize dominant sound sources to the shallow water reef soundscape in Lakshadweep and their correlation with local oceanographic parameters across monsoon and non-monsoon months. Four acoustic bands of interest, namely a geophonic band of wind-driven wave sounds and three biophonic bands containing animal choruses, are presented. Low frequency biophonic choruses peaked in inter-monsoon months, while low frequency geophonic sound levels peaked during monsoon months. Choruses showed site-wise variability and correlation with sea surface salinity, chlorophyll-a, and wind speed. Understanding cetaceans and the underwater soundscape through an oceanographic lens highlight the underlying biological resources and physical drivers in this poorly studied area. This dissertation demonstrates that employing appropriate technology and methodologies can shed light on even highly mobile species (such as blue whales) in challenging conditions. Within the context of a changing climate, the information presented here can provide a baseline to compare with future cetacean and soundscape studies in this region. Furthermore, the dissertation emphasizes that current plans for tourism development in these islands need to incorporate potential impacts on near-island cetacean communities and on underwater noise

Cetacean distribution and diversity in Lakshadweep waters, India, using a platform of opportunity: October 2015 to April 2016

Prior stranding records suggest that at least 12 cetacean species occur within the Lakshadweep archipelago off the southwest coast of India. These islands consist of coral atolls and form the northern part of the undersea Chagos-Laccadive ridge. Distinct oceanographic features, seasonal monsoon cycles, and high productivity make this region a potentially rich cetacean habitat In this article, we report findings from the first systematic visual cetacean surveys, which were conducted from high-speed passenger ferries that sail between nine Lakshadweep islands. The surveys were carried out between October 2015 and April 2016 during both the northeast monsoon (October to December) and inter-monsoon (January to April) seasons. We used a line-transect survey framework to record sightings as well as group size estimates. We documented 139 sightings over 3,880 km of which 78 sightings were during systematic survey effort. Eight odontocete species were confirmed from these sightings: Stenella longirostris, S. attenuata, S. coeruleoalba, Tursiops spp., Globicephala macrorhynchus, Pseudorca crassidens, Grampus griseus, and Feresa attenuata. One Balaenoptera sp. was also encountered during this survey. S. longirostris was sighted the most often (n = 22) followed by Tursiops spp. (n = 18) and G. macrorhynchus (n = 13). We documented significantly higher sightings in the northeast monsoon season compared to the intermonsoon season. Along ferry routes, cetacean species differed significantly from each other with respect to their associations with seafloor slope gradients and distances to nearest landmass. We encountered mixed species assemblages of G. macrorhynchus with Tursiops sp. and S. attenuata with Tursiops sp. Given the confirmed high cetacean diversity and occurrence in this region, there is a need for in-depth, long-term studies on biogeography, ecology, and population status of cetaceans here

Humpback dolphins (Genus Sousa) in India: an overview of status and conservation issues

This chapter aims to collate recent work done by different research teams along the Indian coast and presents research plans for the conservation and management of the genus Sousa in Indian waters. Humpback dolphins are the most common nearshore cetaceans found along the Indian coast. The taxonomy is confused, but two or more species of humpback dolphins may be present in India. Dedicated research on humpback dolphins and other cetaceans has been initiated only in the past few years and vast gaps in the ecology and conservation of the genus from the region remain. Dedicated and opportunistic research indicates that humpback dolphin presence is continuous along the west coast of India, owing to the contiguous favourable habitat of shallow nearshore waters, while along the east coast humpback dolphins are apparently found in pockets. Humpback dolphins are also the most numerous in incidental catch records from the coast, owing to the large overlap in space use with nearshore fisheries like small gillnets, trawls, shore seines and purse seines. Along many coastal sites, humpback dolphins are known to cause damage and depredation of fish catch of certain fishing gears, making them unpopular. At the same time, many fishers along the west coast have developed local dolphin-watching programmes as an alternate source of livelihood, providing positive impetus for conservation. However, research on the long-term effects of dolphin watching and its management is required. Some recommendations for more effective management of this species are made