School of Convict Surgeonfish at the Waiopae Tidepools Dr.Grabowski at Honaunau Bay,Hawaii Green Sea Turtle at Onekahakaha, Hawaii Robust Redhorse staging for spawning in the Savannah River, Georgia-South Carolina Reef herbivores at Kealakekua Bay, Hawaii Atlantic Cod in production facility in GRindavik, Iceland Texas Logperch Achilles Surgeonfish and Yellow Tang Dr. Grabowski relaxes after setting up hydrophone array at Kollafjordur, Iceland Yellow Tangs at Kealakekua Bay, Hawaii Dr.Grabowski examines a Spotted Bass on the Brazos River, Texas Green Sea Turtle at the Waiopae Tidepools, Hawaii Electrofishing in the South Llano River Rio Grande at Santa Elena Canyon Dr. Grabowski listening to Burbot calling in Moyie Lake, British Columbia Ornate Butterflyfish at Kealakekua Bay, Hawaii Sunset from a jet-powered kayak on Lake Livingston

Current projects being worked on in the Grabowski Lab

Fishpond wall

Assessing the functional equivalency of Hawaiian fishponds relative to natural estuaries for nearshore fisheries

Hawaiian fishponds represent a significant fraction of the available estuarine habitat in the state, yet are virtually unstudied from a fisheries ecology perspective. This research addresses knowledge gaps on the function of inactive/abandoned fishponds in the Hawaiian nearshore environment relative to natural estuaries and the role both inactive/abandoned and active fishponds play in the dynamics of exploited nearshore species and non-native invasive species. The objectives of this study are to 1) compare the abundance and species composition of the nekton inhabiting a complex of Hawaiian estuary ecotypes consisting of an inactive/abandoned fishpond, two fishponds actively under production, and the adjacent natural estuary; and 2) assess the survival, recruitment, movement, and habitat use of the young-of-year of four fish species commonly associated with fishponds and natural estuaries: Striped Mullet (ʻama ʻama) Mugil cephalus, Kanda Moolgarda engeli, Reticulated Flagtail (aholehole) Kuhlia sandvicensis, and Hawaiian Flagtail (aholehole) Kulhia xenura using mark-recapture methods.

Terminal phase Palenose Parrotfish and images of parrotfish bitemarks

Quantifying parrotfish grazing activity using computer-aided image analysis

Parrotfish (family Scaridae) bitemarks, also referred to as scrapes or scars in the literature, have received considerable scientific attention as they are important to the dynamics of benthic algae and invertebrate populations, coral growth and health, and estimating bioerosion rates. Despite being visually distinctive, quantifying and measuring parrotfish bitemarks can be a time- and labor-intensive process which limits the utility of surveying bitemarks are a monitoring tool. The objectives of this study are to 1) develop an automated methodology to quantify parrotfish grazing activity from photographs taken of the reef surface; 2) validate the precision and accuracy of estimates generated using automated methods relative to manual counts; and 3) relate estimates generated by automated methodology to parrotfish species composition, size composition, and relative abundance.

An assortment of reef fishes pose for a deployed camera.

Development of a low-cost, near-360° camera system as a tool to assess reef fish occupancy, behavior, and fine-scale habitat use

The use of game trail cameras has revolutionized the study of terrestrial wildlife. Technological advancements with action cameras would seem to offer a similar opportunity for studying underwater wildlife. We have developed a low-cost underwater camera system using off-the-shelf technology with the goal of using it to conduct research on the habitat use, distribution, behavior, and demographics of reef fishes. This is a long-term project with the potential for numerous studies. However, at the moment we are pursuing three objectives: 1)comparing species composition, detection probabilities, and relative abundance estimates between the camera-based system and visual surveys; 2) evaluating whether the factors influencing occupancy and abundance of selected fish species differ between the Wai‘ōpae Marine Life Conservation District (MLCD) and adjacent unprotected areas; and 3) constructing high-resolution, 3D models of reef fish habitat use. The Grabowski Lab is working on this project in collaboration with Dr. John Burns at the University of Hawaii-Hilo and Dr. Sarah Fritts at Texas State University.

Male Flame Wrasee and associated track in breeding tank

Understanding the relationship between behavior and sequential hermaphroditism in endemic Hawaiin reef fishes

Reef fishes lead interesting sex lives. Numerous taxa have evoloved life history strategies where individuals begin life as one sex, only to transition to the other at a later point. These sequential hermaphrodites pose unique challenges to conservation and management efforts. The objectives of this study are to 1) describe the mating systems of several endemic Hawaiian reef fishes, including Flame Wrasse Cirrhilabrus jordani, Potter’s Angelfish Centropyge potteri, and Hawaiian Longfin Anthias Pseudanthias hawaiiensis; and 2) evaluate how behavioral interactions between individuals influences the transition from female to male. This long-term project represents the first collaborative effort between the Hawaii Cooperative Fishery Research Unit and the Pacific Aquaculture and Coasral Resources Center (PACRC).

Peacock Grouper (roi) arrives at cleaning station

Evaluating the influence of founder effects on local adaptation in reef fishes

The primary objectives of this study are to 1) quantify the degree to which Peacock Grouper (roi) Cephalopholis argus exhibit localized adaptions in morphology, diet, and life history traits associated with environmental gradients in the main Hawaiian Islands and the Northwest Hawaiian Islands and 2) characterize the how these traits have changed relative to populations in its native range since the species was introduced to Hawaii in the 1950s. There are a number of secondary objectives associated with this study including 1) evaluating the effects of repeated removal efforts on a Peacock Grouper population in the newly established fish replenishment area at Kaʻūpūlehu; 2) archive materials for assessing the occurrence and prevalence of ciguatera in Hawaii; and 3) continue data collection activities associated with community-based invasive species removal efforts throughout Hawaii.