Kenneth Sebens

Non-additive effects of air and water warming on an intertidal predator–prey interaction

Marine Biology, Mar 15, 2018

Climate change alters multiple physical drivers that act concurrently on ecological communities. ... more Climate change alters multiple physical drivers that act concurrently on ecological communities. Evidence suggests widespread non-additive effects between multiple drivers; most of this evidence, however, is based on species-level responses, which is problematic because community responses to environmental change also depend on species interactions. To address this knowledge gap, this study experimentally manipulated two physical drivers and examined the responses of a predatorprey interaction. The two drivers tested are fundamental in intertidal systems: air and water temperatures. The two species were the intertidal dogwhelk, Nucella ostrina, and its barnacle prey, Balanus glandula. The objective was to test alternative hypotheses that air and water warming have additive vs. non-additive effects on the whelk-barnacle interaction. A 14-day mesocosm experiment was conducted in which animals were subjected to one of four temperature treatments: ambient (no temperature manipulation; water 12 °C, air 13 °C), warm water (15 °C), warm air (27 °C), or combined (water 15 °C, air 27 °C). There were two key findings. First, air and water warming non-additively affected interaction strength: warm water mitigated a 35% decrease in mean whelk feeding rate caused by warm air. Second, air warming had contrasting effects on individual growth rates of predator and prey. While whelk growth decreased by ~ 60% in warm air, barnacle growth increased by 47%. These findings suggest that combined air and water warming will benefit barnacle populations more than their whelk predators. This study highlights the value of integrating species performances and interactions to understand how multiple physical drivers may affect community structure.

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Urban Ecosystems, Feb 24, 2018

Urbanization is a process that heavily alters marine and terrestrial environments, though terrest... more Urbanization is a process that heavily alters marine and terrestrial environments, though terrestrial urban ecosystems have been studied far more intensively. Terrestrial studies suggest that urbanization can facilitate mesopredators by enhancing food and shelter resources and reducing predation pressure from apex consumers. This in turn has considerable consequences for ecological communities. We evaluated spatial distribution patterns and habitat-use of the marine mesopredator, giant Pacific octopus (Enteroctopus dofleini), relative to terrestrial urbanization intensity in Puget Sound, Washington, USA. Using field surveys and citizen-contributed data for E. dofleini, we examined whether: (1) Distribution was related to urbanization, (2) Abundance was related to the extent of benthic anthropogenic debris, and (3) Diet differed as a function of urbanization and den cover. Our results suggest that urbanization impacts may differ with depth. Mixed-effects logistic regression model estimates for the probability of occurrence increased with urbanization in deep-water (> 24 m), and decreased with urbanization in shallow water (< 18 m). Accompanying field surveys indicated that E. dofleini abundance was correlated with the number of benthic anthropogenic debris items, and that E. dofleini diets were not affected by urbanization intensity or den cover. Though E. dofleini may be synanthropic within certain urban environments, the mechanisms driving this pattern likely differ from those affecting common urban mesopredators on land, with den provisioning from man-made structures being more important than altered food resources.

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Habitat structure and community dynamics in marine benthic systems

Springer eBooks, 1991

Animals and plants of the marine benthos depend on their substrata for attachment, on surfaces or... more Animals and plants of the marine benthos depend on their substrata for attachment, on surfaces or within sediments, and for access to a source of prey and nutrients. In the case of sessile species, the two-dimensional surface is a primary resource for which individuals and colonies of many species potentially compete. However, substratum is not as simple a resource as one might expect. Even solid rock surfaces are usually dissected by small to large crevices, have different orientations with respect to each other and to water flow, and are often made of varied rock types. Soft substrata can be extremely diverse, consisting of both organic and inorganic materials differing in grain sizes and in chemical composition. These materials are further modified through the activities of the residents themselves, adding organic material, aggregating particles and sometimes changing the nature of the substratum so much that other species can be totally excluded. On hard substrata, biogenic effects can also be extremely important. These include the provision of secondary substratum through growth processes and calcium carbonate deposition, and the addition of physical relief that affects water flow and thus the transport of resources and propagules within the community.

Marine flora and fauna of the eastern United States : Anthozoa:Acitniaria [i.e. Actiniaria], Corallimorpharia, Ceriantharia, and Zoanthidea

A~~i8llinl A{liuinU!lr.llor fur I'i,hrrir. "Illr' ,"(lJ(J 1t1lh..,rtJ/ JUpMI nll•;S {lSSN OR!I2-B... more A~~i8llinl A{liuinU!lr.llor fur I'i,hrrir. "Illr' ,"(lJ(J 1t1lh..,rtJ/ JUpMI nll•;S {lSSN OR!I2-B9OR• tnic1 H puhWhed b)-Foreward ____________________________________________________ _ This NOAA Technical Report NMFS is part of the subseries "Marine Flora and Fauna of the Eastern United States" (formerly "Marine Flora and Fauna of the Northeastern United States"), which consists of original, illlustrated, modern manuals on the identification, classification, and general biology of the estuarine and coastal marine plants and animals of the eastern United States. The manuals are published at irregular intervals on as many taxa of the region as there are specialists available to collaborate in their preparation. These manuals are intended for use by students, biologists, biological oceanographers, informed laymen, and others wishing to identify coastal organisms for this region. They can often serve as guides to additional information about species or groups. The manuals are an outgrowth of the widely used "Keys to Marine Invertebrates of the Woods Hole Region," edited by R. 1. Smith, and produced in 1964 under the auspices of the Systematics Ecology Program, Marine Biological Laboratory, Woods Hole, Massachusetts. Geographic coverage of the "Marine Flora and Fauna of the Eastern United States" is planned to include organisms from the headwaters of estuaries seaward to approximately the 200-m depth on the continental shelf from Maine to Florida, but can vary somewhat with each major taxon and the interests of callaborators. Whenever possible, representative specimens dealt with in the manuals are deposited in the reference collections of major museums. The "Marine Flora and Fauna of the Eastern United States" is being prepared in collaboration with systematic specialists in the United States and abroad. Each manual is based primarily on recent and ongoing revisionary systematic research and a fresh examination of the plants and animals. Each manual, treating a separate major taxon, includes an introduction, glossary, uniform originally illustrated key, annotated checklist (with information, when available, on distribution, habitat, life history, and related biology), references to the major literature of the group, and a systematic index.

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Biodiversity of Coral Reefs: What are We Losing and Why?

American zoologist, Feb 1, 1994

SYNOPSIS. Coral reefs are threatened by numerous anthropogenic impacts, some of which have alread... more SYNOPSIS. Coral reefs are threatened by numerous anthropogenic impacts, some of which have already had major effects worldwide. These unique tropical environments harbor a high diversity of corals, reef invertebrates, fish and other animals and plants. In most taxa, the species diversity of reef-associated organisms is poorly understood because many of the species have yet to be collected and described. High coral mortality has been associated with natural events such as hurricanes, predator outbreaks and periods of high temperature, but has also resulted from excess nutrients in sewage and from specific pollutants. Reef corals and associated organisms are also threatened by the possibility of global warming which will result in rising sea levels and periods of increased temperature stress, and which may also bring increased storm frequency and intensity. Although the recent extensive episodes of coral bleaching in the Caribbean and eastern Pacific cannot be causally related to global warming at this time, the close link between bleaching and temperature suggests that global warming will result in severe changes in coral assemblages. Major reef destruction has followed outbreaks of the predatory seastar Acanthaster planci in the Pacific. Although this is considered part of a natural disturbance cycle, there are indications that altered land use patterns and reduction of predators on this seastar by human activities may have increased the severity of outbreaks. Recreational and commercial use of reefs has also increased, and has caused extensive damage, especially near areas of high population density. One of the most obvious and widespread losses to reef biota is the reduction in fish populations from intense overfishing in most reef areas of the world. Coasts without adequately managed reefs have suffered intense overfishing for both local and export purposes, to the point where the positive effects of fish on those reefs have been compromised. The combination of these destructive factors has altered reefs in all localities, and many that were once considered protected by distance and low population density are now being exploited as well. On the positive side, improved understanding of ecological processes on reefs combined with concerted conservation efforts have managed to protect some extensive areas of reef for the future.

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In situ measurements of flow effects on primary production and dark respiration in reef corals

Limnology and Oceanography, Jul 1, 1991

The effects of flow on the physiological ecology of Montustrea annuluris, an important framebuild... more The effects of flow on the physiological ecology of Montustrea annuluris, an important framebuilding species of Caribbean coral reefs, were investigated in situ with a recirculating flow respirometry system deployed from an underwater habitat. For this species, primary production and respiration rates increase with increasing water motion. The slope of a nondimensional Sherwood (Sh)-Reynolds(Re) number plot indicates that forced convection increases dark respiration in a manner consistent with oxygen transfer through a turbulent boundary layer (Sh = 0.01Re'.30). A similar analysis for maximal photosynthetic rate yields a lower but significant slope (Sh = 0.7 1 Reo.63). A simple conceptual model of diffusional depletion in the boundary layer over the coral fits the data and accounts for the distribution of zooxanthellae. Calculations of phototrophic capacity for this species indicate that water motion can enhance the local productivity of the reef.

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Ocean warming and the demography of declines in coral body size

Marine Ecology Progress Series, Nov 24, 2016

Reductions in body size are hypothesized to be a universal response to climate warming, yet the p... more Reductions in body size are hypothesized to be a universal response to climate warming, yet the proximate causes of change remain unresolved. In this study, we combined field evidence and demographic models to explore mechanisms relevant to temperature-related declines in the body size of an ectotherm exhibiting indeterminate growth. Our field data demonstrate that the body size of cup corals Balanophyllia elegans has decreased by ~35% over nearly 4 decades (1969−2007), during which seawater temperatures have increased by 0.6°C in the San Juan Islands, Washington State, USA. We developed a modeling framework, based on the Arrhenius equation and temperature−size theory, to explore the thermal dependence of maximum body size. Our models identified the growth rate of corals as a key demographic leverage point for changes in maximum body size, but temperature alone was likely insufficient to cause the observed magnitude of change. Our case study provides a simple template for integrating detailed demographic data with predictions derived from the temperature−size theory, in order to evaluate empirically the magnitude of body size decline in the context of climate warming.

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Particulate matter ingestion and associated nitrogen uptake by four species of scleractinian corals

Coral Reefs, Jun 26, 2004

... Matthew M. Mills Æ Fredric Lipschultz Kenneth P. Sebens ... measured on Bermuda's oceani... more

Feeding biology and ecological impact of an introduced nudibranch,Tritonia plebeia, New England, USA

Marine Biology, Oct 1, 1988

The nudibranchTritonia plebeia (Johnston) was first observed in New England in 1983, on vertical ... more The nudibranchTritonia plebeia (Johnston) was first observed in New England in 1983, on vertical rock walls at 7 m depth off Nahant, Massachusetts. This northern European species preys exclusively on the soft coralAlcyonium digitatum (Linneaus) in its natural habitat. At Nahant, it preyed primarily on the closely relatedAlcyonium siderium Verrill. Laboratory studies indicated that it could locate its prey by

Artificial structures as a source of elevated detrital loads for sedimentary environments

Bulletin of Marine Science, Oct 1, 2018

Artificial structures, such as seawalls and breakwaters, are essential components of shoreline pr... more Artificial structures, such as seawalls and breakwaters, are essential components of shoreline protection, yet they can have major consequences for marine organisms, particularly those in surrounding sediments. Improved understanding of the mechanisms by which artificial structures influence sedimentary habitats and the scale at which these mechanisms operate is needed to assess impacts of intensifying shoreline armoring on nearshore ecosystems. We examined detrital production on artificial structures and influx into surrounding sedimentary habitat in Puget Sound, Washington. Benthic surveys of hard substrates and drift composition indicated that red macroalgae and encrusting invertebrates were the major producers of detrital material on subtidal artificial structures in the region. Core samples collected at three distances (1, 7, and 15 m) from selected artificial structures revealed that these materials were moving into adjacent sedimentary seascapes and becoming incorporated into the upper layers of sediment. Though detrital influx occurred only in the immediate vicinity of artificial structures, it altered sediment characteristics considerably, increasing the quantity of shell fragments and thus the average grain size, as well as the concentration of red macroalgal detritus in sediments. Furthermore, rapid turnover rates of macroalgal detritus in experimental sediment plots suggested the influx of red macroalgal material from artificial structures was a frequent occurrence. These results indicate that elevated detrital influx is a persistent process in habitats bordering artificial structures in Puget Sound. Further work is needed to assess ecosystem response to detrital influx and to understand detritus-related impacts of shoreline armoring at the landscape scale.

Coelenterata

Elsevier eBooks, 1987

Forced convection modulates gas exchange in cnidarians

Proceedings of the National Academy of Sciences of the United States of America, Nov 1, 1989

Boundary layer thickness is a potentially important component of the diffusive pathway for gas ex... more Boundary layer thickness is a potentially important component of the diffusive pathway for gas exchange in aquatic organisms. The soft coral Akyonium siderium (Octocorallia) and sea anemone Metridium senile (Actiniaria) exhibit significant increases in respiration with water flow over a range of Reynolds numbers encountered subtidally. A nondimensional mass transfer analysis of the effect of forced convection demonstrates the importance of the state of the organism's boundary layer in regulating metabolism in these invertebrates. Flow-modulated gas exchange may limit secondary productivity in subtidal environments.

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Coexistence of Clones, Clonal Diversity, and the Effects of Disturbance

Yale University Press eBooks, Apr 26, 2018

Nitrate uptake by the reef coral Diploria strigosa: effects of concentration, water flow, and irradiance

Marine Biology, Nov 30, 2005

The effects of several environmental variables on net nitrate uptake by the scleractinian coral D... more The effects of several environmental variables on net nitrate uptake by the scleractinian coral Diploria strigosa were investigated under controlled flow conditions. D. strigosa exhibited nitrate uptake rates ranging from 1-5 nmol cm À2 h À1 at ambient concentrations of 0.1-0.3 lM that are typical of oligotrophic reefs such as Bermuda. Net uptake ceased at approximately 0.045 lM. The uptake was positively correlated with concentration up to a saturation concentration of approximately 3 lM. The uptake was also positively correlated with water velocity at 1 lM, but not at 6 lM, suggesting diffusional limitation at low concentrations and kinetic limitation at higher concentrations. Nitrate uptake by D. strigosa was not affected by light intensity or time of day, but was almost completely inhibited by 48 h exposure to ammonium levels found on many reefs.

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Dissolved oxygen and temperature recorded from 2018-2020 from a sensor array that measures pH, pCO2, temperature, salinity, dissolved oxygen, chlorophyll, turbidity, and current velocity at Friday Harbor Laboratories Ocean Observatory (FHLOO)

Dissolved oxygen (O2) and temperature recorded from 2018-2020 from a sensor array that measures p... more

Energetics, Particle Capture, and Growth Dynamics of Benthic Suspension Feeders

Springer eBooks, 2017

Marine benthic communities are dominated by suspension feeders, including those actively pumping ... more Marine benthic communities are dominated by suspension feeders, including those actively pumping water, passively encountering particles, or some combination of the two. The mechanisms by which particles are encountered and retained are now well known for a range of water flow conditions and organism morphologies. Recent research has attempted to quantify the energetic components of suspension feeding, including intake of particles, pumping rates, and metabolic costs of these activities. Energetic models depend strongly on environmental conditions, including temperature, flow speed, and food availability, for example. The effects of these variables have been combined for realistic scenarios using dynamic energy budget (DEB) models, and related models to examine components of fitness (growth, reproduction, population increase), for both existing conditions and for conditions expected for future environments. Detailed examples are provided from recent research on bivalve mollusks, cnidarians including sea anemones and corals, and barnacles. These examples cover several major phyla that are often important components of intertidal and subtidal benthic communities. All common phyla of benthic suspension feeders are discussed, though less extensively, especially given the paucity of energetics studies for some of these phyla.

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Marine flora and fauna of the eastern United States: Anthozoa: Actiniaria, Corallimorpharia, Ceriantharia, and Zoanthidea

A~~i8llinl A{liuinU!lr.llor fur I'i,hrrir. "Illr' ,"(lJ(J 1t1lh..,rtJ/ JUpMI nll•;S {lSSN OR!I2-B... more A~~i8llinl A{liuinU!lr.llor fur I'i,hrrir. "Illr' ,"(lJ(J 1t1lh..,rtJ/ JUpMI nll•;S {lSSN OR!I2-B9OR• tnic1 H puhWhed b)-Foreward ____________________________________________________ _ This NOAA Technical Report NMFS is part of the subseries "Marine Flora and Fauna of the Eastern United States" (formerly "Marine Flora and Fauna of the Northeastern United States"), which consists of original, illlustrated, modern manuals on the identification, classification, and general biology of the estuarine and coastal marine plants and animals of the eastern United States. The manuals are published at irregular intervals on as many taxa of the region as there are specialists available to collaborate in their preparation. These manuals are intended for use by students, biologists, biological oceanographers, informed laymen, and others wishing to identify coastal organisms for this region. They can often serve as guides to additional information about species or groups. The manuals are an outgrowth of the widely used "Keys to Marine Invertebrates of the Woods Hole Region," edited by R. 1. Smith, and produced in 1964 under the auspices of the Systematics Ecology Program, Marine Biological Laboratory, Woods Hole, Massachusetts. Geographic coverage of the "Marine Flora and Fauna of the Eastern United States" is planned to include organisms from the headwaters of estuaries seaward to approximately the 200-m depth on the continental shelf from Maine to Florida, but can vary somewhat with each major taxon and the interests of callaborators. Whenever possible, representative specimens dealt with in the manuals are deposited in the reference collections of major museums. The "Marine Flora and Fauna of the Eastern United States" is being prepared in collaboration with systematic specialists in the United States and abroad. Each manual is based primarily on recent and ongoing revisionary systematic research and a fresh examination of the plants and animals. Each manual, treating a separate major taxon, includes an introduction, glossary, uniform originally illustrated key, annotated checklist (with information, when available, on distribution, habitat, life history, and related biology), references to the major literature of the group, and a systematic index.

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Individual marking of soft-bodied subtidal invertebrates in situ – A novel staining technique applied to the giant plumose anemone Metridium farcimen (Tilesius, 1809)

PLOS ONE, Nov 21, 2017

The ability to recognize individuals and track growth over time is crucial to population dynamics... more The ability to recognize individuals and track growth over time is crucial to population dynamics research as well as studies of animal behavior. Invertebrates are particularly difficult to track as they often molt, have regenerative capabilities, or lack hard parts to attach markers. We tested, in laboratory and field studies, a new way of marking sea anemones (order Actiniaria) by injection of three vital stains (i.e., neutral red, methylene blue, and fluorescein). Neutral red and methylene blue did not affect growth or survival, but fluorescein was lethal at high concentrations. Marked individuals could be identified up to seven months after injection with neutral red, six weeks with methylene blue, and three days with low concentrations of fluorescein. Neutral red could be used for long-term monitoring of growth and survival in the field, and in combination with methylene blue could be used to mark individuals in distinguishable patterns for short-term studies such as examining predator-prey interactions, movement of individuals, and recruitment survival.

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The North-East Pacific

Interactions in the Marine Benthos, 2019

Settlement and Metamorphosis of a Temperate

The temperate soft-coral Alcyonium siderium Verrill has a demersal planula larva which usually se... more The temperate soft-coral Alcyonium siderium Verrill has a demersal planula larva which usually settles and metamorphoses on vertical rock surfaces near the parent colony. Such surfaces are covered by a variety of encrusting invertebrate species and by three common crustose algae (Lithothamnium glaciale, Phymatolithon rugolosum, and Waernia mirabilis). Larvae settle and metamorphose most frequently on these three algal species in the field (Sebens, 1983). Contact with each of the three crustose algae induced settlement and metamorphosis within 1-5 days in laboratory experiments. Rock or shell fragments, even with naturally filmed surfaces, did not induce metamorphosis in the same time period. A few larvae did metamorphose on the rock, shell, and glass or plastic surfaces of the containers, taking up to 30 days to do so. Larvae were kept alive up to 194 days but their competence to metamorphose declined significantly after ten days. The half-life of larvae that did not metamorphose was approximately 25 days. Larvae presented with coralline algae in darkness delayed metamorphosis by approximately 10-20 days, but most of them did metamorphose by 30 days. Neither sea water incubated with coralline algae, nor coralline algae in close proximity (45 mm) to the larvae, but without contact, induced metamorphosis. Induction of settlement and metamorphosis is thus mediated by surface contact with the algae and probably not by a dissolved chemical. Presence of the colonial ascidian, Aplidium pallidum, inhibited metamorphosis even when larvae were able to contact coralline algae, and also caused early larval death. INTRODUCTION The planulae of octocorals are usually brooded by the adult colony to a swimming stage (Matthews, 1917; Gohar, 1940; Hartnoll, 1975, 1977; Weinberg, 1979; Weinberg and Weinberg, 1979) which settles and crawls on the substratum. They may also be released as demersal crawling larvae (Hartnoll, 1977). The swimming larvae are similar in morphology and behavior to those of certain scleractinian corals (Abe, 1937; Atoda, 1947a, b, 1951a, b, c, 1953; Kawaguti, 1941, 1944; Harrigan, 1972a, b; Lewis 1974), hydroids (Nishihara, 1967a, b, 1968a, b; Donaldson 1974), scyphozoans (Brewer, 1976a, b; Neumann, 1979), and sea anemones (Chia and Spaulding, 1972; Siebert, 1973). Behavior of the demersal planulae is similar to that described for scleractinian corals (Gerrodette, 1981; Fadlallah and Pearse, 1982; Fadlallah, 1983), certain hydroids (Williams, 1965, 1976), and hydrocorals (Ostarello, 1973, 1976). Settlement and substratum choice has been studied for few anthozoans [reviewed by Chia and Bickell (1978)], and for even fewer octocorals (Theodor, 1967; Chia and Crawford, 1973; Weinberg, 1979; Weinberg and Weinberg, 1979). Received 23 November 1982; accepted 1 April 1983.

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