scholarly journals Specialization of a mobile, apex predator affects trophic coupling among adjacent habitats

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Carl S. Cloyed ◽  
Rachel M. Wilson ◽  
Brian C. Balmer ◽  
Aleta A. Hohn ◽  
Lori H. Schwacke ◽  
...  
Keyword(s):  
Narrow Range ◽  
Bottlenose Dolphins ◽  
Regional Scale ◽  
Trophic Levels ◽  
Habitat Specialization ◽  
Apex Predators ◽  
Freshwater Input ◽  
Marine Habitats ◽  
Trophic Coupling ◽  
Seagrass Cover

AbstractMobile, apex predators are commonly assumed to stabilize food webs through trophic coupling across spatially distinct habitats. The assumption that trophic coupling is common remains largely untested, despite evidence that individual behaviors might limit trophic coupling. We used stable isotope data from common bottlenose dolphins across the Gulf of Mexico to determine if these apex predators coupled estuarine and adjacent, nearshore marine habitats. δ13C values differed among the sites, likely driven by environmental factors that varied at each site, such as freshwater input and seagrass cover. Within most sites, δ13C values differed such that dolphins sampled in the upper reaches of embayments had values indicative of estuarine habitats while those sampled outside or in lower reaches of embayments had values indicative of marine habitats. δ15N values were more similar among and within sites than δ13C values. Data from multiple tissues within individuals corroborated that most dolphins consistently used a narrow range of habitats but fed at similar trophic levels in estuarine and marine habitats. Because these dolphins exhibited individual habitat specialization, they likely do not contribute to trophic coupling between estuarine and adjacent marine habitats at a regional scale, suggesting that not all mobile, apex predators trophically couple adjacent habitats.

scholarly journals The Indo-Pacific Amalda (Neogastropoda, Olivoidea, Ancillariidae) revisited with molecular data, with special emphasis on New Caledonia

2020 ◽  
Author(s):  
Yuri I. Kantor ◽  
Magalie Castelin ◽  
Alexander Fedosov ◽  
Philippe Bouchet
Keyword(s):  
Gene Flow ◽  
Molecular Analysis ◽  
New Caledonia ◽  
Narrow Range ◽  
Regional Scale ◽  
Molecular Data ◽  
Shell Morphology ◽  
Species Limits ◽  
South West ◽  
Strait Of Malacca

In the ancillariid genus Amalda, the shell is character rich and 96 described species are currently treated as valid. Based on shell morphology, several subspecies have been recognized within Amalda hilgendorfi, with a combined range extending at depths of 150–750 m from Japan to the South-West Pacific. A molecular analysis of 78 specimens from throughout this range shows both a weak geographical structuring and evidence of gene flow at the regional scale. We conclude that recognition of subspecies (richeri Kilburn & Bouchet, 1988, herlaari van Pel, 1989, and vezzaroi Cossignani, 2015) within A. hilgendorfi is not justified. By contrast, hilgendorfi-like specimens from the Mozambique Channel and New Caledonia are molecularly segregated, and so are here described as new, as Amalda miriky sp. nov. and A. cacao sp. nov., respectively. The New Caledonia Amalda montrouzieri complex is shown to include at least three molecularly separable species, including A. allaryi and A. alabaster sp. nov. Molecular data also confirm the validity of the New Caledonia endemics Amalda aureomarginata, A. fuscolingua, A. bellonarum, and A. coriolis. The existence of narrow range endemics suggests that the species limits of Amalda with broad distributions, extending, e.g., from Japan to Taiwan (A. hinomotoensis) or even Indonesia, the Strait of Malacca, Vietnam and the China Sea (A. mamillata) should be taken with caution.

scholarly journals SECONDARY PRODUCTION OF Scolelepis goodbodyi (POLYCHAETA: SPIONIDAE) IN A TROPICAL SANDY BEACH IN THE SOUTHWESTERN ATLANTIC, BRAZIL

2020 ◽  
Vol 24 (04) ◽  
pp. 819-833
Author(s):  
Luciana Sanches Dourado Leão ◽  
◽  
Abílio Soares-Gomes ◽  
José Roberto Botelho de Souza ◽  
Cinthya Simone Gomes Santos ◽  
...  
Keyword(s):  
Growth Rate ◽  
Secondary Production ◽  
Environmental Variability ◽  
Trophic Levels ◽  
Southwestern Atlantic ◽  
Web Studies ◽  
Marine Habitats ◽  
Production Values ◽  
Annual Biomass ◽  
Density And Biomass

The secondary production is the result of the functional response of populations subject to various environmental factors. Marine habitats vary in terms of quantity and quality of food supply, and the use of secondary production values, as well as renewal rates (P/B), may be used as estimates for understanding the incorporation of organic matter and energy per unit, population or community in each area. This estimative was performed for the population of Scolelepis goodbodyi in a tropical beach in the Southwestern Atlantic, located in an upwelling area. A comparison of Spionidae and non-spionid populations from different latitudes was also done. The Mass Specific Growth Rate method (MSGR) and the Production/Biomass ratio (P/B) were used to estimate the somatic annual production and average annual biomass. The mean density and biomass were 16.38 ind. m-2 and 2.78 g AFDW m-2,respectively. The secondary production and P/B were 8.3 g AFDW m-2 y-1 and 2.98 y1, respectively. The growth rate in weight was greater for the small size than the large size classes. The largest individuals (W3C = 1.0 mm) showed the lowest biomass and secondary production values. The observed high rates of secondary production and P/B suggest that this S. goodbodyi population can transfer large amounts of biomass to higher trophic levels of the local food web. Studies of the secondary production of spionidae populations in different latitudes, including the population of S. goodbodyi in the beach of Manguinhos, showed variability in their rates probably due to the differences of several factors such as life history and environmental variability

scholarly journals Integrating passive acoustic and visual data to model spatial patterns of occurrence in coastal dolphins

2014 ◽  
Vol 72 (2) ◽  
pp. 651-660 ◽  
Author(s):  
Paul M. Thompson ◽  
Kate L. Brookes ◽  
Line S. Cordes
Keyword(s):  
Spatial Variation ◽  
Spatial Patterns ◽  
Classification Tree ◽  
Bottlenose Dolphins ◽  
Regional Scale ◽  
Habitats Directive ◽  
Line Transect ◽  
Species Identity ◽  
Passive Acoustic ◽  
Survey Effort

Abstract Fine-scale information on the occurrence of coastal cetaceans is required to support regulation of offshore energy developments and marine spatial planning. In particular, the EU Habitats Directive requires an understanding of the extent to which animals from Special Areas of Conservation (SAC) use adjacent waters, where survey effort is often sparse. Designing survey regimes that can be used to support these assessments is especially challenging because visual sightings are expected to be rare in peripheral parts of a population's range. Consequently, even intensive visual line-transect surveys can result in few encounters. Static passive acoustic monitoring (PAM) provides new opportunities to extend survey effort by using echolocation click detections to quantify levels of occurrence of coastal dolphins, but this does not provide information on species identity. In NE Scotland, assessments of proposed offshore energy developments required information on spatial patterns of occurrence of bottlenose dolphins in waters in and next to the Moray Firth SAC. Here, we illustrate how this can be achieved by integrating data from broad-scale PAM arrays with presence-only data from visual surveys. Generalized estimating equations were used with PAM data to model the occurrence of dolphins in relation to depth, distance to coast, slope, and sediment, and to predict the spatial variation in the cumulative occurrence of all dolphin species across a 4 × 4 km grid of the study area. Classification tree analysis was then applied to available visual sightings data to estimate the likely species identity of dolphins sighted in each grid cell in relation to local habitat. By multiplying these probabilities, it was possible to provide advice on spatial variation in the probability of encountering bottlenose dolphins from this protected population at a regional scale, complementing data from surveys that estimate average density or overall abundance within a region.

scholarly journals Exceptionally high but still growing predatory reef fish biomass after 23 years of protection in a Marine Protected Area

PLoS ONE ◽  
2021 ◽  
Vol 16 (2) ◽  
pp. e0246335
Author(s):  
Irene Rojo ◽  
José Daniel Anadón ◽  
José Antonio García-Charton
Keyword(s):  
Reef Fish ◽  
Carrying Capacity ◽  
Fish Assemblages ◽  
Marine Protected Area ◽  
Regional Scale ◽  
Trophic Levels ◽  
Trophic Groups ◽  
Total Recovery ◽  
Entire Study

Marine Protected Areas (MPAs) help replenish fish assemblages, though different trophic levels may show diverse recovery patterns. Long-term protection is required to achieve total recovery but poaching events may prevent the achievement of full carrying capacity. Here, we have analysed the effect of long-term protection on the entire reef fish community and the different trophic levels in the Cabo de Palos-Islas Hormigas MPA (SE Spain; SW Mediterranean Sea) in order to assess their recovery patterns after 23 years of protection. We compared the values for carrying capacity obtained with the maximum values achieved at regional scale, and we assessed the effect of a reduction in the surveillance over a few years, during which poaching events increased, on the recovery patterns. We found that, overall, biomass of fishes increased with time while density diminished. In particular, piscivorous and macro-invertivore fish increased while the other trophic groups remained constant or declined, suggesting top-down processes. For the entire study period, those trophic groups were approaching carrying capacity; however, when accounting only for the period in which enforcement was high and constant, they grew exponentially, indicating that full carrying capacity may have not been achieved yet. When compared to other Mediterranean MPAs, the Cabo de Palos-Islas Hormigas MPA showed values for biomass that were disproportionately higher, suggesting that local factors, such as habitat structure and associated oceanographic processes, may be responsible for the dynamics found. Our results help to understand the potential trajectories of fish assemblages over a consolidated MPA and highlight empirically how the reduction of surveillance in a period may change the recovery patterns.

scholarly journals Actively restored ecosystems as a refuge for biological diversity: A case study from eelgrass (Zostera marina L.)

2015 ◽  
Author(s):  
Jonathan Lefcheck ◽  
Scott R Marion ◽  
Robert J Orth
Keyword(s):  
Zostera Marina ◽  
Biological Diversity ◽  
Trophic Levels ◽  
Critical Element ◽  
Invertebrate Community ◽  
Western Atlantic ◽  
Goods And Services ◽  
Nearshore Ecosystems ◽  
General Decline ◽  
Seagrass Cover

As nearshore ecosystems are increasingly degraded by human activities, active restoration is a critical element in ensuring the continued provision of goods and services by coastal habitats. Since 1997, over 1800 ha of the foundational species eelgrass (Zostera marina L.) has been reestablished in the coastal bays of the mid-western Atlantic. Here, we follow the functional recovery of the epifaunal invertebrate community associated with a restored eelgrass habitat from 2001-2013. Epifauna provide critical services by removing fouling epiphytes from eelgrass blades and transferring energy to higher trophic levels. After less than a decade, the invertebrate community in the restored bed was richer, more even, and exhibited greater variation in functional traits than a nearby natural bed. Analysis of environmental and physical data using random forests revealed the primary drivers of these differences was the increasing area and density of the restored bed directly attributable to both ongoing restoration efforts, and expansion from the initial planting efforts. Given that restored eelgrass now make up 32% of total seagrass cover in the mid-Atlantic, this restoration may foster regional biodiversity by providing new and pristine habitat, particularly given the general decline of natural eelgrass in this region and globally.

Fisheries

2007 ◽  
Author(s):  
John R. Beddington ◽  
Geoffrey P. Kirkwood
Keyword(s):  
Trophic Level ◽  
Global Scale ◽  
Trophic Levels ◽  
Predatory Fish ◽  
Apex Predators ◽  
The North ◽  
The Mean ◽  
Mean Trophic Level ◽  
Global Statistics ◽  
United Nations Food

The depletion of fish stocks on a global scale is well documented. The United Nations Food and Agriculture Organisation collects statistics on fisheries from all states and, despite obvious shortcomings in the data, a clear picture has been available for some time. Garcia and Grainger (2005) have succinctly documented the position from the latest available date: in 2003, only 3% of stocks were underexploited and 26% moderately exploited, while 52% were fully exploited, 16% were overfished, 7% were depleted, and 1% were recovering from earlier depletion. These global statistics mask two important phenomena. The first, highlighted by Pauly et al. (1998), is that fisheries are increasingly focusing on species lower down in the food-web and the second, highlighted by Myers and Worm (2003, 2005), is that large predatory fish have been particularly reduced in abundance. Both of these analyses are somewhat flawed. In the case of Pauly et al. there are two problems: the first is that the metrics used for the mean trophic level are presented as simple numbers with no estimates of error or indeed sensitivity. In such a situation, the changes in mean trophic levels are hard to interpret, particularly where the mean trophic level changes by at most around 10% over four decades. The second problem has been highlighted by a recent paper by Essington et al. (2006). They point out that in the periods when according to the analysis of Pauly et al. the mean trophic level was declining, in most cases catches of apex predators and indeed all upper trophic levels increased (an exception is the North Atlantic). In the case of the Myers and Worm analysis, they used the catch per unit of effort (CPUE) as an index of abundance. As discussed later in this chapter, there are problems with this, but more importantly for some key apex predators, in particular large tunas, the CPUE declines in the early stages of the fishery, where catches are small, but remains relatively stable under a regime of much higher catches. In such a situation, the interpretation that the CPUE reflects changes in abundance is clearly problematic.

Influence of boat anchoring on Pinna nobilis: a field experiment using mimic units

2015 ◽  
Vol 66 (9) ◽  
pp. 786 ◽  
Author(s):  
Maite Vázquez-Luis ◽  
Joseph A. Borg ◽  
Carlos Morell ◽  
Gàlia Banach-Esteve ◽  
Salud Deudero
Keyword(s):  
Adverse Effect ◽  
Field Experiment ◽  
Posidonia Oceanica ◽  
Shoot Density ◽  
Size Classes ◽  
Pinna Nobilis ◽  
Marine Habitats ◽  
Seagrass Cover ◽  
Different Levels ◽  
Global Density

Anchoring by recreational boats causes several different effects on marine habitats and species. The influence of boat anchoring on the Mediterranean endemic bivalve Pinna nobilis was assessed experimentally in the field by deploying non-biological mimic units of the bivalve around the islands of Mallorca and Malta. In each of these two localities, two study areas having different levels of boat anchoring activities, namely, ‘control’ (no anchoring allowed) and ‘affected’ (anchoring allowed), were used for the field experiment. A significant number of P. nobilis mimic bivalves were affected by boat anchoring; the influence was three times higher at anchoring sites than in control areas. Boat anchoring also had an adverse effect on Posidonia oceanica meadows, with seagrass cover, shoot density and global density being lower in the anchoring areas. Moreover, lower values of natural P. nobilis density and size classes were recorded from the anchoring areas.

scholarly journals Trophodynamics and stability of regional scale ecosystems in the Northeast Atlantic

2012 ◽  
Vol 69 (5) ◽  
pp. 764-775 ◽  
Author(s):  
Niall McGinty ◽  
Anne Marie Power ◽  
Mark P. Johnson
Keyword(s):  
Control Charts ◽  
Marine Ecosystem ◽  
Regional Scale ◽  
Trophic Levels ◽  
Northeast Atlantic ◽  
Long Term Stability ◽  
Large Marine Ecosystem ◽  
Trends Over Time ◽  
The Stability ◽  
Multivariate Control

Abstract McGinty, N., Power, A. M., and Johnson, M. P. 2012. Trophodynamics and stability of regional scale ecosystems in the Northeast Atlantic. – ICES Journal of Marine Science, 69: 764–775. This study addresses the long-term stability of three trophic groupings in the Northeast Atlantic at regional scales. The most abundant taxa representing phytoplankton, herbivorous copepods, and carnivorous zooplankton were examined from the Continuous Plankton Recorder database. Multivariate control charts using a Bray–Curtis similarity metric were used to assess whether fluctuations within trophic groupings were within or beyond the expected variability. Two evaluation periods were examined: annual changes between 1960 and 1999 (2000–2009 baseline) and recent changes between 2000 and 2009 (1960–1999 baseline). The trends over time in abundance/biomass of trophic levels were region-specific, especially in carnivorous copepods, where abundance did not mirror trends in the overall study area. The stability of phytoplankton was within the expected limits, although not in 2008 and 2009. Higher trophic levels were less stable, perhaps reflecting the added complexity of interactions governing their abundance. In addition, some regions were consistently less stable than others. Correlations in stability between adjacent trophic levels were positive at large marine ecosystem scale but generally non-significant at regional scales. The study suggests that certain regions may be particularly vulnerable to periods of instability in community structure. The benefits of using the control chart method rather than other multivariate measures of plankton dynamics are discussed.

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