Vertical Habitat Use Research Articles

Ocean scale hypoxia‐based habitat compression of Atlantic istiophorid billfishes

AbstractOxygen minimum zones (OMZs) below near‐surface optimums in the eastern tropical seas are among the largest contiguous areas of naturally occurring hypoxia in the world oceans, and are predicted to expand and shoal with global warming. In the eastern tropical Pacific (ETP), the surface mixed layer is defined by a shallow thermocline above a barrier of cold hypoxic water, where dissolved oxygen levels are ≤3.5 mL L−1. This thermocline (∼25–50 m) constitutes a lower hypoxic habitat boundary for high oxygen demand tropical pelagic billfish and tunas (i.e., habitat compression). To evaluate similar oceanographic conditions found in the eastern tropical Atlantic (ETA), we compared vertical habitat use of 32 sailfish (Istiophorus platypterus) and 47 blue marlin (Makaira nigricans) monitored with pop‐up satellite archival tags in the ETA and western North Atlantic (WNA). Both species spent significantly greater proportions of their time in near‐surface waters when inside the ETA than when in the WNA. We contend that the near‐surface density of billfish and tunas increases as a consequence of the ETA OMZ, therefore increasing their vulnerability to overexploitation by surface gears. Because the ETA OMZ encompasses nearly all Atlantic equatorial waters, the potential impacts of overexploitation are a concern. Considering the obvious differences in catchability inside and outside the compression zones, it seems essential to standardize these catch rates separately to minimize inaccuracies in stock assessments for these species. This is especially true in light of global warming, which will likely exacerbate future compression impacts.

A lifetime at depth: vertical distribution of southern elephant seals in the water column

Although numerous studies have addressed the migration and dive behaviour of southern elephant seals (Mirounga leonina), questions remain about their habitat use in the marine environment. We report on the vertical use of the water column in the species and the potential lifetime implications for southern elephant seals from Marion Island. Long-term mark-resight data were used to complement vertical habitat use for 35 known individuals tagged with satellite-relay data loggers, resulting in cumulative depth use extrapolated for each individual over its estimated lifespan. Seals spent on average 77.59% of their lives diving at sea, 7.06% at the sea surface, and 15.35% hauled out on land. Some segregation was observed in maximum dive depths and depth use between male and female animals—males evidently being physiologically more capable of exploiting increased depths. Females and males spent 86.98 and 80.89% of their lives at sea, respectively. While at sea, all animals spent more time between 300 and 400 m depth, than any other depth category. Males and females spent comparable percentages of their lifetimes below 100 m depth (males: 65.54%; females: 68.92%), though males spent 8.98% of their lives at depths in excess of 700 m, compared to females’ 1.84% at such depths. Adult males often performed benthic dives in excess of 2,000 m, including the deepest known recorded dive of any air-breathing vertebrate (>2,133 m). Our results provide a close approximation of vertical habitat use by southern elephant seals, extrapolated over their lifespans, and we discuss some physiological and developmental implications of their variable depth use.

White Shark Offshore Habitat: A Behavioral and Environmental Characterization of the Eastern Pacific Shared Offshore Foraging Area

BackgroundAlthough much is known about the behavior of white sharks in coastal regions, very little is known about their vertical movements offshore in the eastern Pacific where they spend up to five months. We provide the first detailed description of the offshore habitat use of white sharks in the eastern North Pacific.Methodology/Principal FindingsThis study uses 2-min data from four recovered pop-up satellite archival tags deployed at Guadalupe Island (2002 and 2005). Deployments ranged from 5.4 to 8.2 months. Two predominant vertical patterns were described. The first was a bimodal vertical pattern with time spent at the surface and at depth, which was observed while traveling. The second was a repetitive oscillatory diving mode displayed by sharks in the Shared Offshore Foraging Area (SOFA). For all four datasets the average maximum daily dive depths ranged from 442.5 to 492.8 m and were typically associated with dissolved oxygen concentrations of above 1.7 ml L−1. Although infrequent, occasional dives to near 1000 m with a minimum temperature of 3.9°C and a minimum O2 level of 0.3 ml L−1 were observed.Conclusions/SignificanceRecovered pop-up satellite tags from Guadalupe Island white sharks advance our understanding of the vertical habitat use of white sharks while offshore. The bimodal vertical pattern during traveling is most likely related to geolocation. The oscillatory dive pattern is likely associated with foraging. While feeding is not documented, foraging is likely occurring in association with the deep scattering layer. Diving depths were not limited by temperature but were constrained by O2 levels below approximately 1.5 ml L−1. While oxygen may limit the extent of sharks' vertical movements, it will also impact prey distribution. Consequently, the shallow oxygen minimum zone in the SOFA may act to concentrate prey, thus enhancing foraging opportunities in these oligotrophic waters.

The amphibian community at Yanayacu Biological Station, Ecuador, with a comparison of vertical microhabitat use among Pristimantis species and the description of a new species of the Pristimantis myersi group

We provide information regarding the composition of the amphibian community at Yanayacu Biological Station, on the Amazonian slopes of the Andes of Ecuador, and describe a new species of Pristimantis that is referred to the P. myersi group. The new species is distinguished from other species of the group mainly by its color pattern, and by lacking ulnar and tarsal tubercles. The advertisement call of the new species has two distinct call types, a short call with 1–3 pulses and a long call with a mean of 15.5–18.9 more rapid pulses, which are often produced together in long call series. Finally, we analyze the microhabitat use of Pristimantis species found at Yanayacu and find that there is significant variation in vertical habitat use among Pristimantis, highlighting the ecological diversity of sympatric species.

Determining summer residence status and vertical habitat use of sailfish (Istiophorus platypterus) in the Arabian Gulf

Abstract Hoolihan, J. P. and Luo, J. 2007. Determining summer residence status and vertical habitat use of sailfish (Istiophorus platypterus) in the Arabian Gulf. – ICES Journal of Marine Science, 64. Pop-up satellite archival tags (PSATs) were deployed on 18 sailfish in the Arabian Gulf between 2001 and 2005 to determine summer geoposition and habitat preference. Programmed releases following periods ranging from 110 to 156 d provided an aggregate total of 533 monitoring days of data. Three PSATs failed to report and nine released prematurely after periods ranging from 3 to 93 d. Four were recovered in gillnets after periods ranging from 39 to 90 d, and two transmitted after programmed releases of 127 and 128 d. Pooled archival data from recovered PSATs showed a cumulative mean distribution of 83.9% for total time spent in the upper 10 m, with no significant difference between day and night (χ24 = 0.84, p = 0.93). Depth ranged from 0 to 61 m, and ambient water temperature from 19.7°C to 30.1°C. Linear displacements ranged from 11 to 543 km and were all located inside the Gulf. Satellite- and light-level-derived geopositioning suggested that all fish remained in the Gulf. The two PSATs releasing on schedule validated summer residence inside the Gulf, providing further evidence in support of genetic analyses and conventional mark-recapture studies, which suggested that this billfish population confines itself year-round within a shallow marginal sea area. Preference for near-surface depths suggests a great susceptibility to capture by gillnets and other surface gears, raising concern for the effectiveness of regional management and conservation of the species.

Vertical movement and habitat of opah (Lampris guttatus) in the central North Pacific recorded with pop-up archival tags

Data from 11 pop-up archival transmitting tags attached to opah (Lampris guttatus, F. Lampridae) in the central North Pacific between November 2003 and March 2005 were used to describe their vertical movement and habitat. In the subtropical gyre northwest of the Hawaiian Islands, opah generally inhabited a 50–400 m depth range and 8–22°C temperatures. They were frequently found in depths of 50–150 m at night and in greater depths (100–400 m) during the day, but were constantly moving vertically within this broad range. At night, excursions below 200 m were not uncommon and during the day they were very likely to spend some time at depths <175 m. Their vertical speeds were generally <25 cm s−1 but on one occasion an opah descended at a burst speed of 4 m s−1. Vertical habitat use by individual opah apparently varied with local oceanographic conditions, but over a 24-h period the average temperature experienced was always in the narrow range of 14.7 to 16.5°C.

Deep-diving and diel changes in vertical habitat use by Caribbean reef sharks Carcharhinus perezi

Longline sampling (83 sets) supplemented with 6 pop-off archival transmitting (PAT) tag deployments were used to characterize vertical habitat use by Caribbean reef sharks Carcharhinus perezi at Glover's Reef atoll, Belize. Longline catch-per-unit-effort (CPUE) in 2 shallow reef habitats (lagoon <18 m depth, fore-reef < 40 m depth) underwent significant nocturnal increases for sharks larger than 110 cm total length (TL), but not for smaller sharks. Nocturnal CPUE of small sharks appeared to increase in the lagoon and decrease on the fore-reef, suggestive of movements to avoid larger conspecifics. PAT tag deployments (7 to 20 d) indicate that large C. perezi generally increased the amount of time they spent in the upper 40 m of the water column during the night, and inhabited much greater depths and tolerated lower temperatures than previously described. The wide vertical (0 to 356 m) and temperature range (31 to 12.4°C) documented for this top-predator reveals ecologi- cal coupling of deep and shallow reef habitats and has implications for Marine Protected Area (MPA) design.

Habitat use and social structure of a brown lemur hybrid population in the Berenty Reserve, Madagascar

The population of brown lemurs has rapidly grown since their founders were introduced to the Berenty Reserve. The founders consist of two species (Eulemur fulvus rufus and E. collaris). To characterize the behavior of the population and to examine whether these characteristics affect population growth, I investigated the habitat use and social structure of the population of brown lemurs at Berenty (Berenty Eulemur). Behavior data were collected focusing on horizontal and vertical habitat use, activity rhythms, and intergroup relationships. These data were compared with the data of E. fulvus in other areas, with the previous studies done at Berenty, and with data on Berenty Lemur catta. Berenty Eulemur maintained a home range size comparable to E. f. rufus in the western deciduous dry forest, but was found at a lower level of the forest and had larger overlapping home ranges. Berenty Eulemur use food resources earlier in the morning than L. catta, intergroup conflict was avoided by vocal communication, and Berenty Eulemur made suitable use of their limited habitat. I suggest that a number of behavioral characteristics of Berenty Eulemur may contribute to their population growth.

Patterns of Vertical Habitat Use by Atlantic Blue Marlin (Makaira nigricans) in the Gulf of Mexico

We examined data from pop-up archival transmitting (PAT) tags (n = 18) to characterize aspects of vertical habitat use by blue marlin (Makaira nigricans) from the Gulf of Mexico (GOM). Two of these tags were recovered and provided fine-scale information about diving patterns and the relationship between time at depth and temperature. Similar to previous studies, blue marlin in the GOM spent most of their time at the surface and at temperatures within 3o C of surface temperatures. Time at depth was multimodal and the magnitude of the smaller modes was dependent upon the strength and depth of the thermocline. Importantly, time at depth was a complex function of the temperature change relative to the surface, time of day, lunar phase, and water column structure. Temperature change with depth between the western and eastern GOM and the adjacent western Atlantic Ocean was also examined. The depth range (maximum depths varied between 68 and 388 m) varied widely between fish and did not appear to correspond with any particular magnitude of temperature change relative to the surface. Although these data may help to improve stock assessments that are based upon habitat standardizations of CPUE, progress will be limited until the distribution of feeding activity with depth and other aspects of blue marlin behavior in rela- tion to capture probability are elucidated. RESUMEN Examinamos los datos de marcas archivo por satellite (PAT) (n = 18) para caracterizar los aspectos del uso vertical del habitat por el aguja azul (Makaira nigricans) del Golfo de Mexico (GOM). Dos de estas marcas fueron recuperadas y proporcionadron informacion a la escala fina acerca de los patrones de zambullir y la relacion entre tiempo en la profundidad y la temperatura. Semejante a estudios previos, el aguja azul en el GOM gasto la mayor parte de su tiempo en la superficie y en zonas dentro de 3°C de temperaturas en la superficie. El tiempo en la profundidad fue multimodal y la magnitud de los modos mas pequenos fueron dependientes sobre la fuerza y la profundidad del termoclino. Importantemente, el tiempo en la profundidad fue una funcion compleja referente al

Effects of Predation Risk on Vertical Habitat Use and Foraging of Pardosa milvina

AbstractAnimals face the risk of predation while engaging in regular activities, such as foraging, mate‐seeking, and reproducing. In order to avoid predation, prey can modify behavior to prevent capture. Pardosa milvina may climb in response to chemotactile cues of Hogna helluo, a larger cooccurring wolf spider, to avoid predation. The purpose of this study was to test the effects of the location of predator cues on the climbing response of P. milvina and to test how this antipredator behavior affected foraging success. In experimental arenas, when cues were on the bottom of the containers, P. milvina moved upward, and when cues were on the walls, individuals moved downward. These results suggest that P. milvina respond to H. helluo cues with general avoidance and do not automatically climb in response to the cues. As H. helluo spend most of their time on the ground, P. milvina may avoid predation by spending more time climbing in areas with H. helluo cues. The presence of predator cues significantly decreased foraging by P. milvina. But within the predator cue treatments, climbing ability had no effect on foraging, possibly due to the short height of the feeding arenas. Future studies are needed to determine if climbing by P. milvina in response to cues of H. helluo has direct and indirect negative effects on herbivores in the field.

Vertical habitat utilization by large pelagic animals: a quantitative framework and numerical method for use with pop‐up satellite tag data

AbstractA quantitative framework and numerical methodology were developed to characterize vertical habitat utilization by large pelagic animals and to estimate the probability of their capture by certain types of fishing gear. Described are the steps involved to build ‘vertical habitat envelopes’ from data recovered from an electronically tagged blue marlin (Makaira nigricans) as well as from a longline fishing gear experiment employing temperature–depth recording devices. The resulting vertical habitat envelopes, which integrate depth and temperature preferences of tagged fish, are conducive for comparative studies of animal behavior and for calculation (and visualization) of degrees of overlap – be it among individuals, species or fishing gear. Results of a computer simulation evaluation indicated our numerical procedure to be reliable for estimating vertical habitat use from data summaries. The approach appears to have utility for examining pelagic longline fishing impacts on both target and non‐target species and could point to ways of reducing bycatch via modification of fishing strategy or gear configuration.

Testing the ecological relevance of Daphnia species designations

Summary1. Molecular approaches have increasingly revealed hidden genetic structure within ecologically important species, leading to the creation of sibling species whose ecological relevance is often unclear. A prime example is Daphnia galeata mendotae, which was split into D. dentifera and D. mendotae based on differences at two allozyme loci.2. In a set of lake populations in Michigan USA, we test the geographical and temporal consistency of the genetic structure underlying this species split. We also test the morphological relevance of this molecular variation and its ecological significance in lakes. In essence, we ask: does recognition of these new species provide valuable information for plankton ecologists?3. We found that D. dentifera and D. mendotae represent morphologically and ecologically distinct forms that are distributed among lakes in non‐random fashion, which were remarkably stable over 6 years. Key differences between the species concern their body and head shape, vertical habitat use within lakes and distribution among lakes of different size. We hypothesise that these differences represent specialisation to habitats that differ in risk of invertebrate predation.4. Reproductive barriers alone are insufficient to explain the pattern of genetic structure; in some lakes complete introgression is apparent. However, parent species and hybrids exhibit a stable co‐existence in many lakes, which suggests that ecological specialisation reinforces divergence within this taxon.

Resource Partitioning in Summer by Salmonids in South-Central Lake Ontario

Abstract During the summers of 1981 and 1982, we studied resource partitioning by stocked lake trout Salvelinus namaycush, brown trout Salmo trutta, and chinook salmon Oncorhynchus tshawytscha by fishing vertical gill nets at six distances from shore in south-central Lake Ontario. The nets were set at depths of approximately 15–45 m (nearshore stations, <4 km offshore) and more than 55 m (offshore stations, 4–24 km offshore). Salmonids were concentrated near shore, where they partitioned available habitat and, thus, food resources. Horizontal habitat was partitioned with respect to distance from shore; vertical habitat was partitioned in relation to temperature and the thermocline. Salmonids foraged for the most available prey items within their habitat. Overlaps in both food use and horizontal habitat use were inversely related to overlap in use of vertical habitat. There was increased habitat separation between sexes for those species caught farther from shore, At the salmonid stocking and prey density ...

Vertical community structure and resource utilization in neotropical forest cockroaches

ABSTRACT. Patterns of vertical habitat use of ten species of cockroaches are examined. Three assemblages of cockroaches are recognized on the basis of morphology, foraging behaviour, foraging heights, and overlaps and breadths of vertical distributions. Three apterous and brachypterous species occur near the ground and comprise one assemblage. They feed mainly on material in the leaf‐litter. Species that perch higher either migrate into the leaf‐litter on a diel basis and feed on both leaf‐litter and epiphyllic materials, or some are strictly arboreal and forage on algae, liverworts, lichens, spores, pollen and trichomes on the surfaces of leaves. Trophic and behavioural correlations with perch height are described and the functions of perching are examined. We conclude that studies of interactions among species are confounded by our lack of understanding of stage‐ and sex‐specific interactions of coexisting species. A simplistic ‘species’approach to such interactions is inadequate because it does not recognize intraspecific variation.

Vertical Habitat Use by Eleutherodactylus Frogs (Leptodactylidae) at Two Costa Rican Localities

Vertical habitat use by frogs of the genus Eleutherodactylus was studied at Monteverde de Puntarenas (five species of four species groups) and Finca La Selva (12 species of six species groups), Costa Rica during June-July 1979. Three patterns of space/time use were recognized: diurnal and ground-active, nocturnal and ground-active, ard nocturnal and aboreal. Juveniles and adults of each species characteristically followed similar patterns. At both localities, diurnal frogs were exclusively ground-active, whereas at night all active individuals were arboreal (except for the rugulosus group). This shift may be tied to physiological constraints (humidity) during the day and selection for call sites at night. THE GENUS Eleutherodactylus (ANURA: LEPTODACTYLIDAE) contains approximately 400 nominal species distributed throughout the neotropics (Lynch 1971). At many sites, members of the genus are the most common inhabitants of the herpetofauna (Heatwole and Sexton 1966, Savage and Emerson 1970, Savage 1975). Costa Rica alone contains 31 nominal species of nine species groups (Savage 1976). Despite its abundance, little information, is available on habitat use by Costa Rican Eleutherodactylus. Most studies are anecdotal (Taylor 1952, 1955; Savage and Emerson 1970; Villa 1972; Savage 1974, 1975) and/or restricted to the leaf litter (Sexton et al. 1964, Heatwole and Sexton 1966, Heyer 1967, Scott 1976). This study discusses vertical habitat use by Fleutherodactylus at two Costa Rican sites, Monteverde de Puntarenas and Finca La Selva. Buskirk and Buskirk (1976) and Talbot (1976) provide descriptions of the climate and vegetation of Monteverde and La Selva, respectively. The p,rimarily morphological species groups of Savage (1976) are used in this study.