My research interests can be broadly classified as fish ecology and physiological ecology. I use both ecological and physiological tools to investigate the trophic biology and energetic strategies of fishes.  Generally I am interested in the role that they play in food webs and how they are adapted to their environments particularly the deep-sea.  However, my interests are diverse so I have tried to outline them below in broad themes.  As for any researcher the themes presented below overlap and for some publications they could be presented in multiple themes.  Links to publication abstracts are also provided.

 

Trophic biology of deep-sea fishes

My dissertation research (at Scripps Institution of Oceanography) dealt with the trophic biology or feeding ecology of Pacific macrourids. The macrourids (see photo below) are one of the most diverse and widespread of all the deep-sea fishes.  These fishes are among the top predators in the deep sea.  An understanding of their feeding ecology has helped determine their role in the deep-sea community and their trophodynamic effects.  Investigation of their feeding and energetics has provided insight into their adaptations to the food limitation imposed by their deep-sea habitat.  The abstract of my thesis and the resulting papers best describe the goals and findings of this work thus far.

 

 

Seasonality in the deep sea

My work has also encompassed the effects of seasonal food supply on deep-sea organisms. The difference between winter and summer are taken for granted in temperate coastal waters but in the deep-sea temperature and the absence of light and primary productivity are constants. Yet there are seasonal signals in some regions of the deep-sea.  In the spring, blooms of phytoplankton in the surface waters occur and soon after due to predation by zooplankton and death of these organisms they slowly sink into the deep-sea.   There is a slow constant rain of these fine particles to the deep sea year-round.  This is the majority of the food for the deep sea.  But after the spring bloom the amount of this material can dramatically increase resulting in a pulse of material than can sometimes blanket the deep-sea floor and provide a seasonal cue for the animals living there.  

Digestive energetic adaptations of deep-sea fishes

I am interested in determining how fishes deal with a food limited environment. One way in which a fish could cope with low food availability is to absorb (assimilate) as much food as possible from every meal. To examine this question the assimilation efficiencies of two deep-sea midwater fishes, Melanostigma pammelas and Lycodapus mandibularis (photos below left and right respectively) in contrast to phylogenetically related shallow living (food rich environments) fishes have been examined. This work is possible because both deep-sea fishes can be captured and then maintained in the laboratory (atmospheric pressure but in situ temperatures).  Hopefully, the scope of this work will be broadened to include other species with the advent of the hyberbaric trap described below.

In addition to controlled laboratory experiments the digestive capabilities can be examined by looking at their digestive enzymes.  Chitin is a substance that makes up crab shells, the pens of squid, and is even found in the body walls of some worms.  It is generally thought that while shallow living fish can break open chitinous exoskeletons to get at the rich protein and lipid inside, they do not actually digest the chitin completely and use it as a food source.  In the deep sea where meals may be scarce perhaps some fishes have evolved the capability to digest chitin completely (its made up of sugar) and use it for food.   The chitinase enzyme activities of a variety of deep and shallow living fishes have been examined and it does appear that quite a few fish have the capacity to completely breakdown chitin to "sugar".   Future work will focus on diversifying the number of species examined and combining the enzyme work with laboratory experiments to determine certain fishes rates of chitin absorption. 

A comparison of assimilation efficiencies between shallow and deep living fishes.

Digestive chitinolytic activity in marine fishes of Monterey Bay, California.

 

Using submarines and remotely operated vehicles (ROVs) to investigate the biology of deep-sea fishes

Since the birth of deep-sea exploration a little over a century ago we have been studying deep sea animals by capturing them in traps or trawls and studying the dead animals in the laboratory.  These investigations have been very fruitful but also limiting.  Over the last two decades advances in technology, primarily human operated vehicles or submarines and remotely operated vehicles (ROVs), robots that are run by scientists safe on board a ship, have allowed us to observe these animals in their environment and dramatically increase our awareness of how deep sea creatures interact with eachother and their environment.  While I was a postdoctoral fellow at MBARI, I used two ROVs to investigate the ecology of deep-sea fishes.  MBARI's ROV Tiburon is shown to the right.  Discoveries include finding a unique site on a submarine plateau offshore of Northern California, where aggregations of blob sculpin, Psychrolutes phrictus, were seen over rocky bottoms. Many of the fish had nests of large pinkish eggs that they appeared to keep clean. This is the first direct evidence of parental care in a deep-sea fish and one of the few documented cases of aggregation in deep-sea fish. These findings are even more interesting because octopuses, Graneledone sp., also choose the site for aggregation and egg brooding.  See the abstract of the paper for more.  Other discoveries include the first observation of a fish-medusa symbiosis in the deep-sea, and interesting first observations of behaviour in several liparid fishes.  Now that I am at the University of Hawaii will to use the Pisces IV and V and the ROV RCV-150 operated by the Hawaii Undersea Research Laboratory to continue with a variety of investigations.

Direct observations of the association between a deep-sea fish and a giant scyphomedusa.

Aggregations of egg brooding deep-sea fish and cephalopods on the Gorda Escarpment: a reproductive hot spot

Hatchlings of the deep-sea octopus Graneledone boreopacifica: are the largest and most advanced known

 

Deep-sea Fisheries

Shallow water fish stocks worldwide are experiencing declines.  As a consequence of these declines and with the advent of new technologies for fishers, stocks of deep-water species have become the targets of developing fisheries.  A couple of examples of deep-sea fishes that you might find at the grocery store are orange roughy, chilean seabass, and grenadier or pacific roughy.  Orange roughy are fished primarily on seamounts at depths of 700 to 1500 meters.  Chilean seabass, also known as Patagonian toothfish, are harvested from the southern ocean at depths of 1000 meters or more.  Grenadiers are members of the diverse family Macrouridae which were formerly known as rattails.  These fishes are being exploited in the North Atlantic and in the North Pacific.  However, research is showing that these fishes do not live in a similar fashion to shallow water stocks.  Deep sea fishes are often long lived, slow to mature, and slow to reproduce (few offspring and possibly years between spawning for an individual).  Research into the reproduction and energetics of these fishes has helped to shed light on these issues.  However, considerably more information is required to examine their life histories so government managers can effectively construct plans for sustainable exploitation.

 

 

Anthropogenic impacts on the deep-sea (CO₂ waste disposal)

The combustion of fossil fuels has drastically elevated atmospheric carbon dioxide (CO₂) levels. This has contributed to global warming. As a nation we have undertaken steps to stabilize CO₂ levels. Currently the reduction of emissions AND the sequestration of CO₂ are being investigated. Sequestration scenarios include pumping of CO₂ (as a liquid) into subterranean aquifers, accumulation of biomass (growing forests etc), and discharging liquid CO₂ into the deep-sea. Current estimates suggest that enormous volumes of CO₂ would have to be pumped into the deep-sea which could effect large regions of this habitat. The CO₂ will remain negatively bouyant as a liquid forming pools in depressions on the seafloor and/or react with seawater to form a solid gas hydrate. Jim Barry (MBARI) and his lab are currently investigating the potential effects that such disposal could have on the deep-sea biota. While a postdoctoral fellow at MBARI, I worked with Jim Barry to examine the response of fishes to in situ discharges of CO₂ on the seafloor.  Considerable data on various components of the benthic community were gathered.  However, data for the fishes was difficult to obtain due to the practicalities of working with large animals remotely and in an uncontrolled environment.  Therefore, with funding from the Department of Energy we designed, built, and began to use a high pressure fish trap to perform controlled laboratory experiments on the tolerances and metabolic responses of deep-sea fishes to elevated CO₂ and low pH (see below).

Direct ocean carbon sequestration: biological impacts during small-scale deep-sea CO₂ releases

 

Live capture and maintenance of deep-sea fishes

Working in collaboration with Jim Barry and engineer, Larry Bird), we have developed a pressurized fish trap to capture fish at depth, bring them to the surface alive, and then either perform controlled experiments under pressure or slowly depressurize them for maintenance at atmospheric pressure.  In situ experiments have proven problematic.  By having a live fish in the laboratory with the capability to alter dissolved gas concentrations, pressure, and temperature a variety of experiments can be performed to examine their physiology and energetics in a manner never before possible.  Furthermore, if fish can be captured and acclimated to atmospheric pressure, possible studies will include energetics, physiology, behavior, sensory biology and more at a level never possible before.  This apparatus has successfully captured two macrourid fishes (Coryphaenoides acrolepis) from 1500 meters and returned them to the surface under in situ temperature and pressure.  The fishes metabolic rates were determined and intial experiments to determine their pressure tolerances were performed.  Many more experiments are planned both off of California and Hawaii over the next year.

4,000 Meter HyperBaric Fish Trap Aquaria Respirometer

 

 

 

Abstracts

Below is a list of abstracts to published papers and works submitted or in press (chronological order). If you would like reprints of published articles please email a request. I am out of reprints for some articles but I can email you electronic copies (pdf files).

 

4,000 meter hyperbaric fish trap aquaria respirometer
Larry B. Bird, Jeffrey C. Drazen, James P. Barry
Abstract presented at the Oceans2004 conference, Kobe, Japan

A major obstacle to the investigation of deep-sea biology is the lack of instrumentation to retrieve deep-sea organisms from their habitat alive and under extreme pressure. The Monterey Bay Aquarium Research Institute (MBARI) has undertaken the technically ambitious goal of building an instrumented high-pressure fish trap aquaria respiration system. The objectives of this project are to capture at depth deep-water fishes, return them to the surface alive at in situ pressure, and maintain them at pressure for up to 60 days. During this 60-day period the specimen can be studied in an environment with regulated pressure, temperature, and seawater chemistry. The key element of this project is an internal pressure vessel capable of containing 6,000 psi (42 MPa) within acceptable safety margins. This high pressure cylinder, 14 inches (35.6 cm) in diameter and 48 inches (122 cm) long, must reliably capture the specimen, close an internal door, seal at depth, and maintain pressure during ascent. This presentation will deal specifically with the design, construction, testing, initial deployments, and success of this system. Design elements include the pressure cylinder, end caps, pressure compensation, instrumentation, flotation package, capture and internal door mechanisms. This system functions autonomously at depths to 4,000 meters and can be deployed on various vessels of opportunity.

 

A comparison of assimilation efficiencies between shallow and deep living fishes
Jeffrey C. Drazen, Bruce H. Robison, and Kim R. Reisenbichler
Abstract presented at the 2004 ASLO conference, Honolulu, Hawaii

In the deep sea food availability is relatively low and meals may be infrequent. Deep-sea fishes may have adapted to these conditions, in part, by utilizing as much food as possible from every meal. We investigated the absorption and assimilation efficiencies of shallow living and deep living zoarcid fishes to determine whether deep-sea species have evolved mechanisms to increase their efficiency of food use. Fishes were placed in experimental chambers and fed a known quantity of food. Ammonia excretion was measured and feces were collected daily. Both food and feces were analyzed for water, protein, lipid and ash to determine specific absorption efficiencies. Preliminary results indicate that there were no differences in absorption or assimilation efficiencies between the species examined. Additional work is being conducted to examine the digestive morphology of all species maintained in the laboratory and how this relates to energetic processes.

 

Direct ocean carbon sequestration: biological impacts during small-scale deep-sea CO₂ releases
James P. Barry, Brad A. Seibel, Jeffrey C. Drazen, Mario N. Tamburri, Kurt R. Buck, Chris Lovera, Linda Kuhnz, Ed Peltzer, Karen Osborn, Patrick J. Whaling, Peter G. Brewer
Deep-Sea Research (submitted)

 

Digestive chitinolytic activity in marine fishes of Monterey Bay, California
Magdalena A. Gutowska, Jeffrey C. Drazen, and Bruce H. Robison
Comparative Biochemistry and Physiology B (in press)

Chitinolytic activities, both chitinase (EC 3.2.1.14) and minimum chitobiase (h-N-acetyl-d-glucosaminidase; EC 3.2.1.30), were measured in stomach and intestinal tissues and their contents, from 13 fish species. Higher activities were found in the tissues than in the gut contents, and higher activities were seen in the stomachs than in the intestines. Demersal species exhibited chitobiase activities very close to their chitinase activities, suggesting that these fishes can degrade chitin completely to its soluble, absorbable monomer, N-acetyl-glucosamine. This suggests that these species may catabolize chitin not just to penetrate prey exoskeletons but also to derive nutrients from the chitin itself. In contrast, three mesopelagic species exhibited low chitobiase but high chitinase activities. This chitobiase limitation correlated strongly with gastrointestinal tract morphology, with the myctophids having the greatest chitobiase limitation and the shortest alimentary tracts. The high chitinase activities measured in the myctophids reflect their ability to rapidly disrupt prey exoskeletons ingested during their nightly feeding in surface waters. Their chitobiase activities are greatly reduced because with rapid meal evacuation through a short gut there is little time for processing and limited energetic advantage in the complete degradation of chitin. These results suggest multiple roles for chitinolytic enzymes in marine fishes and that feeding habits and frequency may have a bearing on the evolution of their digestive enzymes systems.

 

Direct observations of the association between a deep-sea fish and a giant scyphomedusa
Jeffrey C. Drazen and Bruce H. Robison
2004 Marine and Freshwater Behaviour and Physiology 37(3): 209-214

This is a report of evidence of a close symbiotic relationship between the scyphomedusa, Stygiomedusa gigantea and the fish, Thalassobathia pelagica. Images from remotely operated vehicles (ROV) were obtained of the fish swimming on and around the large scyphomedusa. This is the first ever documented symbiosis between an Ophidiform fish and a medusa.

 

Hatchlings of the deep-sea octopus Graneledone boreopacifica: are the largest and most advanced known
Janet R. Voight and  Jeffrey C. Drazen
2004 Journal of Molluscan Studies 70(4): 406-408

Although parts of at least four deep-sea octopus egg clutches have been collected in the last 120 years,1–3 free-living hatchlings have remained unknown. The remotely operated vehicle (ROV) Tiburon documented the hatching of an egg clutch brooded by a female of Graneledone boreopacifica Nesis, 1982 at 1,600 m depth on the Gorda Escarpment and collected 28 hatchlings. The 55-mm long hatchlings are the largest and most developmentally advanced octopus hatchlings known, although their external yolk sacs indicate that hatching was premature. The hatchlings carry up to 57 suckers per arm and the hectocotylus of male hatchlings carries the full adult complement of 42 or 43 suckers. The internal yolk sac displaces the small digestive gland to the ventral, posterior mantle cavity, as is typical of embryos of Octopus vulgaris.

 

Aggregations of egg brooding deep-sea fish and cephalopods on the Gorda Escarpment: a reproductive hotspot
Jeffrey C. Drazen, Shana K. Goffredi, Brian Schlining, and Debra S. Stakes
2003 Biological Bulletin 205: 1-7

Localized areas of intense biological activity or hot spots in the deep sea are infrequent but important features in an otherwise sparsely occupied habitat . Hydrothermal vents, methane cold seeps, and the tops of seamounts are well documented areas where dense communities persist for generations . Reproductive aggregations where conspecifics concentrate for the purposes of spawning and/or egg brooding could be thought of as transient hot spots. It is likely that they occur in populations with low densities in order to maximize mate location and increase reproductive success . However, only a few deep-sea reproductive aggregations have ever been documented demonstrating the paucity of present day information regarding reproductive behavior of deep-sea animals.

In this paper we document a unique multispecies reproductive aggregation located on the Gorda Escarpment, California. We document some of the highest fish and octopus densities ever reported in the deep sea, with a majority of both species brooding eggs. The nesting behavior of the blob sculpin, Psychrolutes phrictus Stein and Bond 1978, and the egg brooding behavior of the octopus, Graneledone sp., during annual ROV dives on the Gorda Escarpment are described. The animals are concentrated at the crest of the local topography and near cold seeps where they may benefit from enhanced current flow and local productivity. These findings provide new information on the reproductive behaviors of deep-sea animals. More importantly they highlight how physical and bathymetric heterogeneity in the environment can result in reproductive hot spots, which may be a critical resource for reproductive success in some deep-sea species.

 

A seasonal analysis of the nutritional condition of deep-sea macrourid fishes in the NE Pacific
Jeffrey C. Drazen
2002 Journal of Fish Biology 60(5): 1280-1295

Fishes living in temperate shallow waters often exhibit seasonal variations in feeding activity and energetics but it is not known whether this occurs in deep-sea fish. In many areas the deep-sea experiences a seasonal influx of organic matter, in the form of phytodetritus, which could provide a seasonal cue for the deep-sea benthos. Gonadosomatic index, enzyme activities, RNA/DNA ratios, proximate composition and lipid class analysis were used to determine the energetic state of three common macrourids, Coryphaenoides armatus Hector, C. yaquinae Iwamoto and Stein, and C. acrolepis Bean in the NE Pacific. Coryphaenoides armatus and C. yaquinae were collected from 1995 to 1998 at an abyssal station, ~220 km west of Point Conception, California in the NE Pacific (4100m depth). Coryphaenoides acrolepis was collected from 1997 to 1998 in the San Diego Trough (1200m depth). Energy storage in all three species was primarily in the liver, which was up to 56% lipid (wet mass) and up to 96% triglyceride. No seasonal variation in biochemical parameters was found for C. armatus or C. yaquinae. However, there was a significant increase in muscle water content and liver lipid content and a significant decline in muscle LDH activity for C. armatus between 1996 and 1998. Potential mechanisms for these interannual shifts are proposed. No seasonal variation in parameters was found for C. acrolepis but a small seasonal periodicity in feeding activity may exist. The seasonal deposition of phytodetritus in the deep sea is of little or no consequence to these fishes.

 

Energy budgets and feeding rates of Coryphaenoides acrolepis and C. armatus
Jeffrey C. Drazen
2002 Marine Biology 140: 677-686

This study develops energy budgets and estimates feeding rates for two macrourid fishes, C. acrolepis, dominant in the bathyal eastern North Pacific, and the abyssal cosmopolitan species, C. armatus. Daily energy expenditure by C. acrolepis was nearly twice that of C. armatus. Coryphaenoides acrolepis allocated nearly equal amounts of energy to metabolism and growth. Once sexual maturity was reached reproduction became the dominant energetic cost. Either these costs are necessary to retain adequate numbers of eggs and larvae on the continental slopes or this fish does not reproduce on an annual basis and the calculated costs are an overestimate. Coryphaenoides armatus allocated relatively more energy to metabolism than growth. It may be semelparous and this strategy would be of great energetic savings in its food-poor but stable environment. Individual daily ration for C. acrolepis decreased from 0.31% to 0.07% of body weight (BW) and for C. armatus from 0.12% to 0.02% BW with increasing fish length. These rates are substantially lower than those for fishes living in cold waters on the continental shelves. The population feeding rates for C. acrolepis ranged from 0.8 to 15 kg km-2 d-1 and for C. armatus from 5 to 2800 g km-2 d-1. The scavenging behaviour of C. acrolepis was used to investigate the role of carrion as a food supply to the deep-sea benthos. It was estimated that the carrion eaten by C. acrolepis is equivalent to 0.04 mg C m-2 d-1 or only 0.2-0.4% of the average small particulate flux. Carrion consumption is important for scavengers like C. acrolepis but it is not an important component of the carbon flux into the deep-sea benthic environment.

 

The feeding habits of slope dwelling macrourid fishes in the eastern North Pacific
Jeffrey C. Drazen, Troy W. Buckley, and Gerald R. Hoff
2001 Deep Sea Research I, 48:909-935

The diet of slope dwelling macrourid fishes in the eastern North Pacific is poorly known. We collected several hundred stomach samples to investigate the feeding habits of Coryphaenoides acrolepis and Albatrossia pectoralis, the two dominant slope dwelling macrourids off the continental United States. Coryphaenoides acrolepis exhibited a pronounced ontogenetic shift in diet. Specimens <15 cm pre-anal fin length (PAF) consumed primarily polychaetes, amphipods, cumaceans, and mysids, while larger individuals consumed increasingly larger, more pelagic prey such as fish, squid, and large crustaceans. Scavenging was also very important to specimens >15 cm with scavenged food comprising approximately 20% of the weight of total prey and occurring in approximately 20% of fish 21-29 cm. Albatrossia pectoralis consumed primarily midwater fish and squid and we believe that it feeds in the water column. There were significant differences between the diets of A. pectoralis and C. acrolepis suggesting some degree of niche separation between macrourid species on the continental slope of the eastern North Pacific. Both species are at the top of the food web on the upper continental slope and, due to their abundance, may exert significant pressures on their prey populations.

 

Feeding ecology of Pacific macrourids
Jeffrey C. Drazen
PhD thesis, UCSD-SIO 2000

Macrouridae is a very common and abundant family of deep-sea fishes. Their environment is characterized by high pressures, low temperatures, dim or no light, and low food availability. Despite these harsh attributes the macrourids are very diverse and widespread. Greater than 300 species are entirely deep living, inhabiting depths from 200 to 6000 meters throughout the world's oceans. The majority of species are benthopelagic, swimming in the water column just over the sediments. Approximately 40 species of macrourids live in the eastern North Pacific and a few are beginning to be commercially exploited.

Macrourids are important study organisms because they are among the apex predators in their environment and their diversity and widespread occurrence make them good subjects for examining energetic strategies in the food-poor deep sea. The goal of my dissertation was to investigate the previously unstudied feeding ecology of several macrourids in the eastern North Pacific Ocean. My study focused on four species, Coryphaenoides acrolepis and Albatrossia pectoralis which are the dominant macrourids on the continental slope and C. armatus and C. yaquinae the dominant species on the abyssal plain.

A diet study found that Coryphaenoides acrolepis had a generalized diet with a pronounced ontogenetic shift. Carrion contributed significantly to its diet suggesting a significant link between surface waters and this species. Albatrossia pectoralis consumed primarily midwater fish and squid and may feed in the water column.

Coryphaenoides acrolepis, C. armatus, and C. yaquinae do not exhibit seasonal variations in nutritional condition. Interannual cycles in condition may be more important than seasonal cycles in the feeding and energetics of the abyssal species. Variable energy storage in C. armatus and C. acrolepis may be the result of sporadic energy inputs due to a scavenging lifestyle and/or continuous reproduction. Seasonal deposition of phytodetritus in the deep sea is of little or no consequence to these fishes.

Analysis of the proximate composition of slope dwelling fishes showed several trends related to depth. Four species had gelatinous muscle (~90% water) including the macrourid Albatrossia pectoralis. Such high water content probably helps this species achieve neutral buoyancy and allows for efficient growth. Considering its principally midwater prey, these characteristics may be adaptations to a midwater lifestyle.

Energy budgets were developed and feeding rates estimated for C. acrolepis and C. armatus. The large reproductive costs in C. acrolepis suggest that either the costs are necessary to retain adequate numbers of eggs and larvae on the continental slopes or this fish does not reproduce annually and the calculated costs are an overestimate. Coryphaenoides armatus may be semelparous, a strategy that would conserve energy in its food-poor but stable environment. Preliminary calculations of cropping rates suggested that these species have significant impacts on their prey. Carrion consumption is important for scavengers like C. acrolepis but it is not an important component of the carbon flux into the deep-sea benthic environment.

 

Biology of Nezumia liolepis (smooth grenadier) and Nezumia stelgidolepis (California grenadier) from the west coast of North America
Gerald R. Hoff, Troy W. Buckley, Jeffrey C. Drazen, and Kanesa M. Duncan
2000 Journal of Fish Biology, 57:662-680

Nezumia liolepis and Nezumia stelgidolepis were collected during a National Marine Fisheries Service 1997 groundfish survey along the Pacific coast of North America. Bottom trawling was conducted from 188 to 1,260 m depths. Nezumia liolepis were collected from 581-1,247 m (3.4 - 5.7º C) and N. stelgidolepis from 285 to 555 m (6.0-8.4º C). The two species had distinct depth and temperature distributions and the majority of the specimens for each species came from narrow depth ranges. Nezumia stelgidolepis attains larger size than N. liolepis, and age estimates from otolith ring counts indicate ages from 3 to 9 years for N. liolepis and 7 and 13 years for N. stelgidolepis from specimens collected. The gonads of N. liolepis were not reproductively active, and a single N. stelgidolepis had developed eggs of various sizes suggesting a batch spawner. Diet analysis indicated N. liolepis and N. stelgidolepis fed benthically, primarily on crustaceans such as amphipods, shrimp, mysids and polychaete worms. Although diet overlap was high, these two species limit competition for resources by habitat separation.

 

Sediment community response to a temporally varying food supply at an abyssal station in the NE Pacific
Jeffrey C. Drazen, Roberta J. Baldwin, and Kenneth L. Smith Jr.
1998 Deep-Sea Research II, 45:893-913

Long time-series measurements were made to examine the effect of episodic inputs of organic matter to the benthic boundary layer on the sediment community at a site in the eastern North Pacific (Sta. M). Chlorophyll a and pheopigments were used to assess sediment enrichment and the response of the sediment community was examined with seasonal measurements of sediment community oxygen consumption (SCOC) and sediment ATP from February 1992 to July 1996. In addition, macrofaunal density and biomass were examined in 26 sediment grab samples taken over a 2 year period. In order to determine whether the presence or absence of detrital aggregates correlated with macrofaunal density and biomass, 54 tube core samples were collected with the submersible Alvin at times when detrital aggregates were present on (August/September of 1994) and absent (April 1995) from the sea floor. Large, seasonal inputs of particulate organic carbon (POC) generally resulted in sediment enrichment and significantly correlated with increases in SCOC. Summer maxima in SCOC occurred consistently over our study period, indicating that this trend is a regular seasonal occurrence at Sta. M. Protozoans, primarily agglutinating foraminiferans, and five of the six dominant metazoan taxa exhibited seasonal increases in density during winter months after detrital aggregates had disappeared from the sea floor and approximately eight months after peak SCOC and POC measurements, over a two year period. Alvin tube core samples showed that relative protozoan density and biomass increased significantly over a four week period following an input of phytodetritus, indicating that these organisms may respond to organic matter inputs on time scales as short as weeks.