Performed the experiments: JR. Analyzed the data: JR. It is well known that microbes, zooplankton, and fish are important sources of recycled nitrogen in coastal waters, yet marine mammals have largely been ignored or dismissed in this cycle. Using field measurements and population data, we find that marine mammals can enhance primary productivity in their feeding areas by concentrating nitrogen near the surface through the release of flocculent fecal plumes. Whales and seals may be responsible for replenishing 2. Even with reduced populations, marine mammals provide an important ecosystem service by sustaining productivity in regions where they occur in high densities.
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Blue whales are little studied, face significant anthropogenic threats and within the Northern Indian Ocean, have a restricted range, making them an archetype for conservation needs of megafauna around the world.
We studied feeding behavior of blue whales using dietary DNA metabarcoding of fecal samples. Within the Indian Ocean sergestids are present within the top m, which correlates with the deep scattering layer observed by hydroacoustics.
Studies suggest that this requirement to dive deeper in search of prey likely explains the prevalence of fluke up diving within this population of blue whales relative to other parts of the globe. Furthermore, this study revealed the presence of acanthocephalan endoparasites within the stomach and intestines of the Northern Indian Ocean blue whales.
This represents the first record of Acanthocephala in blue whales in the Northern Indian Ocean and highlights the need for further studies on both the ecto- and endoparasitic flora and monitoring of health of these cetaceans for their management and conservation. Baleen whales feed on small animals that can be filtered from the ocean using their baleen plates, which act like nets to separate their food from seawater Pivorunas, They regularly feed on euphausiids, copepods, mysids, small fish, and amphipods.
Blue whales Balaenoptera musculus are the archetypal euphausiid-feeding great whales. They are thought to fulfill their energetic needs by feeding on dense schools of their preferred prey, euphausiids, worldwide Yochem and Leatherwood, ; Schoenherr, ; Croll et al.
Large marine predators forage on prey that are spatially and temporally patchy Haury et al. To support their energy requirements, it is assumed that animals target areas that are resource abundant Fauchald and Tveraa, Euphausiids have extremely patchy distributions in comparison to other animals of similar size and in some areas they form aggregations where density is as high as 1, individuals per m 3 Higginbottom and Hosie, , making them an ideal target for lunge filter-feeding of blue whales.
Blue whale movements within and between feeding areas are thought to be driven by the availability of dense patches of such prey Fiedler et al.
Most baleen whale species undertake long-range seasonal migrations between productive high latitude feeding grounds and unproductive, low latitude breeding grounds Brodie, ; Corkeron and Connor, However, because blue whales need to seek regions of exceptionally high productivity Croll et al.
Northern Indian Ocean NIO blue whales Balenoptera musculus indica however, usually remain in low latitude waters throughout the year Alling et al.
A number of their areas of aggregation have been identified, including waters near Somalia Small and Small, , the Seychelles Mikhalev, , the Maldives Ballance et al.
Sighting, stranding and acoustic data Alling et al. More significantly, they have been observed feeding de Vos et al. Many wild animals are elusive or inhabit hostile environments making it nearly impossible to observe them as they undertake critical activities such as feeding, breeding, or escaping predators. The diet of whales while an important aspect of their ecology, is a particularly difficult one to study because of the challenges in linking observed surface behaviors to subsurface foraging activities and ultimately to the food that is consumed.
Furthermore, whales often have vast ranges, are difficult to observe closely at sea, and are available for observation over limited spatial and temporal scales Samuels and Tyack, ; Au et al. In this study of blue whale diet, we used DNA metabarcoding of fecal samples. Feces have previously been extensively used to study diet composition in blue whales and a variety of other species across the world Jarman et al.
More recently fecal samples have also been used for the assessment of parasites in baleen whale species Hunt et al. Protozoan parasites have been detected in both North Atlantic right whales Eubalaena glacialis and bowhead whale feces Balaena mysticetus Hughes-Hanks et al. Therefore the main purpose of this work was to ascertain if the Northern Indian Ocean blue whale also preferentially preyed on euphausiids, as visual observations of diving behavior suggest they may be targeting deeper water species around Sri Lanka de Vos et al.
Secondarily, these samples were used to identify other species such as parasites that exist within the gut flora of the blue whales within the Northern Indian Ocean.
A total of 34 blue whale fecal samples were collected from 16 different encounters during the months of January, February and March off the southern coast of Sri Lanka. The samples were collected opportunistically from the sea surface using a strainer with mesh size 0. Each sample was placed into a sterile sample collection bottle sufficient to fill half the bottle.
The sampled material was a coarse paste of animal particles see Supplementary Material. It was not possible to sample the water where the whale was about to defecate with the same sampling procedure because a coarse mesh sieve cannot be used to sample water and it is not possible to predict when a whale will defecate. Differences among the samples in the DNA sequences produced were used as a proxy for negative water controls.
The first-round PCRs were performed in triplicate and a template-free control reaction was run. Reactions were run on an LC real time quantitative thermal cycler.
Amplification of the template was monitored by EvaGreen fluorescence. These low Ct -values indicate exponential amplification of reasonably concentrated DNA template. A second round of PCR was used to add a unique combination of 10 bp index sequences to the pool of PCR products amplified from each sample McInnes et al.
No combinations of forward and reverse indexes are re-used in the laboratory as a measure to control contamination. Fragments were sequenced on an Illumina MiSeq Sequencer Ilumina using a cycle v2 Nano kit and bp paired-end reads.
The reads were assigned to a sample based on the combination of their forward and reverse indices using the Illumina MiSeq Reporter software. Subsequent sequence processing steps were performed with Usearch7 Edgar, and custom Python scripts to apply the process to the sequences from each of the 16 samples.
Paired reads were then merged with staggered overlaps allowed and the truncqual parameter set to 2. Sequences that occurred only once were removed and clusters created with the clusterfast algorithm with an identity threshold of 0. Centroid sequences were assigned to taxa that they matched most closely as in Jarman et al. No anonymous MOTUs were identified.
Singleton sequences were removed during processing, which is likely to have been effective for removing chimaeric PCR products. The DNA sequence data produced in this study was archived at www. This provides a reasonable basis for metazoan diversity analysis. The results also indicate that blue whales ingested small proportions of other species groups ranging from Amphipoda to Cephalopoda.
Thirty seven percent also indicated consumption of Amphipoda, but generally in lower quantities Figure 1. The short DNA metabarcode that we used only allowed identification to groups of thes taxonomic levels Jarman et al. No metazoan sequences were identified in the template-free negative control reactions. Figure 1. Prey species detected in Northern Indian Ocean blue whale fecal samples. Each column represents a single sample.
Percentage of amplicons belonging to each prey group extracted from samples is indicated. The lack of a consistent, diverse background of amplicons suggests that the primary source of the amplicons amplified from the fecal samples is dietary rather than derived from seawater. Based on the samples collected during this study it is also evident that feeding varied through the study period which ranged from January to March While diet in January comprised predominantly of Dendrobranchiata, the samples from March comprised a wider range of prey species with no species being particularly predominant Figure 1.
The discovery that blue whales in warm tropical waters off Sri Lanka feed predominantly on Dendrobranchiata rather than Euphausiids, their typical primary prey in other areas, demonstrates that blue whales are able to locate and feed on dense swarms of other types of prey when they occur. This parallels observations by Fiedler et al. Previously, Alling et al. Further, the molecular assay that we applied in this study can detect Mysida in mixed samples Jarman et al.
We have presented our DNA metabarcoding results as proportions of reads in each sample because the whale fecal samples are inevitably contaminated with small amounts of trace environmental DNA in seawater.
However, the PCR primer binding sites for the amplicon we sequenced are highly conserved Jarman et al. If environmental DNA contamination was contributing significantly to the overall result, there would be a more consistent influence on the DNA signal found during each time period. The large differences in read composition among samples suggest that the environmental DNA contribution to the DNA pool is small compared to that from the fresh fecal material. Large baleen whales require considerable concentrations of food to make their energetically demanding lunge feeding strategy viable Brodie et al.
The range of species documented in the diet of blue whales during this study is unsurprising given that their feeding behavior involves lunging into prey patches and filtering prey Pivorunas, ; Goldbogen et al. This feeding adaptation makes it impossible to feed selectively on small prey and the results support a non-selective feeding strategy. The presence of Cephalapoda in one sample reflects this non-selectivity in feeding Clarke, Sergestidae, the predominant prey of NIO blue whales as suggested by this study, primarily ingest euphausiids and copepods, while the rest of their diet comprises chaetognaths, ostracods, and radiolarians with some evidence of phytoplankton, protists and cnidarian nematocysts Tavares and Martin, Given that sergestids, like other small zooplankton species are movement limited and restricted to diel vertical migrations Steele, , they are likely densest in areas where they can encounter their favored prey items.
This further explains the small quantities of chaetognaths, copepods and euphausiids in the diet of the blue whales in this study Figure 1. The variation in prey availability during the months of January, February and March indicate that seasonal variation occurs within the water column and is likely driven by changes in circulation resulting from Sri Lanka's monsoonal climate de Vos et al.
They are primarily mesopelagic during the day with much of the assemblage exhibiting diel vertical migration into the epipelagic zone at night Donaldson, ; Walters, Sergestids are an abundant component of oceanic micronekton and because of their zooplanktivorous habits are an important link between zooplankton and higher trophic levels in pelagic ecosystems Yousuf, Other species of the Genus Sergia have been recorded in day time trawls at varying depths up to 2, m Vereshchaka, The deep scattering layer that has been previously recorded at approximately m within the study area may therefore comprise this prey species see Supplementary Material.
Feeding on these epibenthic animals necessitates deeper foraging dives. These whales have been observed accelerating in to the terminal surfacing as they present the high arch and then the fluke de Vos et al. Blue whale dive depths are known to closely track the depth distributions of euphausiids, as indicated by a correlation in vertical space off the coast of California Croll et al. Research from Monterey Bay indicates that blue whales concentrated their foraging activity on deeper layers of euphausiids located between and m on the canyon edge Croll et al.
Research off the Channel Islands, California indicated that blue whales foraged at similar dive depths Croll et al. More recently, Goldbogen et al. In Sri Lanka, blue whale dive duration averaged Based on this available data, we hypothesize that NIO blue whales are deep divers with the potential to reach depths of approximately m. This coincides with the depths at which some species of Sergestidae have been recorded within the Indian Ocean Karuppasamy et al.
Further, this coincides with the depth of the deep scattering layer documented within this area during pilot hydroacoustic surveys conducted in March see Supplementary Material.
In comparison, spinner dolphins caught in the tuna driftnet fishery in the Sulu Sea dove to — m to feed on sergestids Dolar et al. In Hawaii, spinner dolphins are known to closely track the mesopelagic boundary community as they migrate vertically through the water column diurnally.
This community reaches a depth of — m during the day and is spread between 0 and m at night Benoit-Bird and Au, Baleen whales have an estimated trophic level of 3. In the southern ocean, blue whales like other baleen whale species feed on the abundantly available Euphausia superba Wiedenmann et al. Dendrobranchiata are voracious omnivores that feed on euphausiids and mysids Tavares and Martin, , changing the trophic position of blue whales in the food chain of the NIO. The finding that NIO blue whales prey on Sergestidae, a predator of euphausiids, introduces an additional trophic level to the blue whale food web in Sri Lankan waters.
A 1 , Haque. ASM 2 , Hossain. Before going to the definition of overfishing we need to know the Definition of bycatch. After a catch is hauled aboard, the non-commercial marine life, is culled out and thrown back, known as "bycatch". Bycatch is not limited to unwanted fish species.
George Karleskint started teaching in and has been at St. Louis Community College, Meramec, since Karleskint enjoys teaching because it gives him the opportunity to help students understand the wonders of life and the special, and even somewhat mysterious, biological world in which they live. George first became interested in marine biology as a child, on trips to Florida when he wanted to know more about the shells he collected.
The Whale Pump: Marine Mammals Enhance Primary Productivity in a Coastal Basin
There is a year round population of whale sharks in the Maldives, the site of extensive research on these awesome sharks. Maldives Whale Shark Research Programme www. The awesome whale shark is not exhibited at the Aquarium. This information is available so you can learn more about the largest fish in the world and its conservation needs. World wide in tropical and warm temperate waters most commonly between latitudes 30 o N and 35 o S in oceanic and coastal waters with the exception of the Mediterranean Sea.
Nurdles are small plastic pellets about the size of a lentil. Countless billion are used each year to make nearly all our plastic products but many end up washing up on our shores. Like other plastics, nurdles can be mistaken for food by marine wildlife like seabirds, fish, and crustaceans. Once polluting our environment, they can pose a threat to these creatures and habitats for years to come. This is because nurdles are tiny, persistent and potentially toxic. Due to their size, and often clear colour, nurdles can look like fish eggs or other small animals which makes them particularly attractive to seabirds, fish and other marine wildlife. More than marine species have been shown to ingest plastic debris. Plastic can get trapped in an animal's stomach causing ulceration, making them feel full and stopping them eating real food.
Learn which whales were hunted and why; how they captured and processed them; how technology changed the industry. Whaling was an exceptionally dangerous business both physically and economically. In the Yankee whale fishery injuries and death were common to almost every voyage.
I recommend it unreservedly it to individuals, students, and researchers, as well as libraries. I worship this book! Its amazing and a must for marine mammal fanatics. Contains all you need to know, is written my many researchers and includes references for further reading. His specialties are behavior and social strategies, especially as related to human disturbance. He has published and co-published about peer review papers, over 50 popular articles, and 7 books. His work with the sense organs of modern whales explores the impact of global change on marine mammal populations. Access Online via Elsevier Bolero Ozon. Encyclopedia of Marine Mammals.
These sharks are recognizable not just for being the largest fish in the sea, growing longer than 40 feet, but also for their unique pattern of blue-gray to brown coloration with white spots centered between pale horizontal and vertical stripes. They are filter feeders, often swimming near the surface of the open sea, gulping in water and filtering everything from plankton and fish eggs, to crustaceans and schooling fish, to occasional larger prey like squid or tuna. Despite their size, they are considered harmless to humans, and will often interact docilely with divers to the extent of allowing the divers to grab on to a fin and hitch a ride. Whale shark , basking shark, and whaleshark are common names in the English language used to refer to this fish. In the past, the whale shark has been of little interest to man. At present, commercial fisheries for whale sharks are limited, but may expand from an increased demand for food products. In Taiwan approximately whale sharks are taken annually. The whale shark meat fetches a high price in this country, and this fact has stimulated larger harvests over the last years.
The Encyclopedia of Marine Mammals , Third Edition covers the ecology, behavior, conservation, evolution, form and function of whales, dolphins, seals, sea lions, manatees, dugongs, otters and polar bears. This edition provides new content on anthropogenic concerns, latest information on emerging threats such as ocean noise, and impacts of climate change. With authors and editors who are world experts, this new edition is a critical resource for all who are interested in marine mammals, especially upper level undergraduate and graduate students, researchers, and managers, and is a top reference for those in related fields, from oceanographers to environmental scientists. His specialties are behavior and social strategies, especially as related to human disturbance. He has published and co-published about peer review papers, over 50 popular articles, and 7 books. His work with the sense organs of modern whales explores the impact of global change on marine mammal populations.
It provides a treasured source of recreation for humans. It is mined for minerals salt, sand, gravel, and some manganese, copper, nickel, iron, and cobalt can be found in the deep sea and drilled for crude oil. Oil Rig off Santa Barbara.
They concentrate in areas of increased biological productivity, such as upwellings where there is an abundant supply of food. Some species are coastal, and some are pelagic, dwelling farther offshore. The centres of the ocean basins appear not to have any concentrations of whales or dolphins. Some small cetaceans are distributed in major river systems, particularly river dolphins of the family Platanistidae.
Cambridge University Press Bolero Ozon. Intergovernmental Panel on Climate Change. Working Group II.